ELECTROCARDIOGRAM UPDATED MAIN plus.docx

**ELECTROCARDIOGRAM : POSSIBLE IMPLICATION OF CHANGES THE NURSE SHOULD KNOW** **UGONSA SCIENTIFIC SESSION SERIES** EDITED BY **NUR. G.I. NSHI,** RN, RPON, B.N.Sc, M.Sc, DNP© **& Lady Obi Ihuoma A.,** RN, RM, RPHN, RNE, BNSc, MScN, FWACN^2^ ^1^ School of Nursing and Health Science, Aspen Universi...

**ELECTROCARDIOGRAM : POSSIBLE IMPLICATION OF CHANGES THE NURSE SHOULD KNOW** **UGONSA SCIENTIFIC SESSION SERIES** EDITED BY **NUR. G.I. NSHI,** RN, RPON, B.N.Sc, M.Sc, DNP© **& Lady Obi Ihuoma A.,** RN, RM, RPHN, RNE, BNSc, MScN, FWACN^2^ ^1^ School of Nursing and Health Science, Aspen University, Denver, Colorado, U.S.A. ^2^Department of Nursing Science, Ebonyi State University, Abakaliki, Nigeria. **Corresponding and Presenting Authors: Nur. G.I. Nshi, & Lady Obi Ihuoma A.,; ** **Objectives** Learners should at the end of the lecture be able to: 1. Identify the structures of the cardiac conduction system and their functions 2. Identify normal sinus rhythm on an ECG strip 3. Describe the characteristics and causes of arrhythmias 4. Identify arrhythmias on ECG strips 5. Measure heart rate through ECG strip **Overview of Anatomy and Physiology of the Heart** The heart is made up of four chambers, namely, the right atria, left atria, the right ventricle and left ventricle. The atria receive blood while ventricles pump blood. The heart is a specialized muscle structure made up of myocardial cells, which are grouped closely together forming intercalated disks, which allow the groups of muscles to function together as one. This allows the atria and ventricles to contract independently of each other. Cardiac muscle also adapts to the amount of blood that it needs to pump. There is a direct proportion between the amount of blood returning to the heart and the force of contraction which empties the ventricle. The greater the amount of blood entering the heart, the stronger the contraction. This is caused by the heart muscle stretching to accommodate the amount of blood. This ability is called **Frank-Starling's Law of the Heart.** The heart muscle cells (the myocardium) have a long rest period which is called the refractory period between contractions. This allows the heart chamber enough time to fill with blood before the next contraction. C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture3.JPG **Properties of Cardiac Muscle Cells** Cardiac muscle cells have four properties 1. Cardiac muscle cells provide their own stimulation. They do not have nerve innervations like skeletal muscles do. This is called **automaticity.** 2. Cardiac muscle cells can respond or react to an electrical impulse. This is called **excitability.** 3. Cardiac muscle cells also have **conductivity,** the ability to transmit an impulse to another cardiac cell. 4. Cardiac muscle cells also have **contractility**, the ability to contract after receiving an impulse. **What is Electrocardiogram (ECG)?** An electrocardiogram (ECG) *or electrocardiogram (EKG) (German version)* is a simple, painless test that measures the electrical activity of the heart using electrodes placed on the patient\'s limbs and on the surface of the chest.  During each heartbeat, a healthy heart has an orderly progression of depolarization that starts with [pacemaker cells](https://en.wikipedia.org/wiki/Pacemaker_cells) in the SA [node](https://en.wikipedia.org/wiki/Sinoatrial_node), spreads out through the [atrium](https://en.wikipedia.org/wiki/Atrium_(heart)), passes through the [AV node](https://en.wikipedia.org/wiki/Atrioventricular_node) down into the [bundle of His](https://en.wikipedia.org/wiki/Bundle_of_His) and into the [Purkinje fibers](https://en.wikipedia.org/wiki/Purkinje_fibers), spreading down and to the left throughout the [ventricles](https://en.wikipedia.org/wiki/Ventricle_(heart)). This orderly pattern of depolarization gives rise to the characteristic ECG tracing. To the Nurse, an ECG conveys a large amount of information about the structure of the heart and the function of its electrical conduction system. Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the [heart chambers](https://en.wikipedia.org/wiki/Heart_chambers), the presence of any damage to the heart\'s muscle cells or conduction system, the effects of cardiac drugs, and the function of implanted [pacemakers](https://en.wikipedia.org/wiki/Artificial_pacemaker). **THE ECG WAVES** Normal rhythm produces four entities --- a P wave, a QRS complex, a T wave, and a U wave --- that each have a unique pattern. - - - - However, the U wave is not typically seen, and its absence is generally ignored. Changes in the structure of the heart and its surroundings (including blood composition) change the patterns of these four entities. Additional components of the ECG waves include PR interval (PRI), PR segment, ST segment and QT interval. Isoelectric line is the baseline reading between cardiac cycles when no electrical activity occurs. **The Cardiac Cycle** ### Electrocardiogram grid ECGs are normally printed on a grid. The horizontal axis represents time, and the vertical axis represents voltage. The standard values on this grid are shown in the images below: - - The \"large\" box is represented by a heavier [line weight](https://en.wikipedia.org/wiki/Font_weight) than the small boxes. The standard rate at which paper moves is 25mm per seconds. Every 3 seconds there is vertical mark at top of the paper. An ECG rhythm strip is usually a 6-second strip consisting of 30 large blocks  C:\\Users\\GOODLUCK NSHI\\Pictures\\ECG GRID.JPG  C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG  **P-WAVE** P -- Wave represents depolarization of the atria \[conduction of an electrical impulse from sinoatrial (SA) node through atria\]. Atria depolarization spreads from the sinoatrial (SA) node towards the Atrioventricular (AV) node and from the right atrium to the left atrium. The P- wave is typically upright (in leads I and II) and usually rounded and smooth. An inverted P-wave indicates an ectopic pacemaker. Normal duration is less than 120 milliseconds (. i.e., 0.12s or 3 small boxes) \[acceptable range is 0.06 to 0.12 second\]. The amplitude of p-wave is 2 to 3 mm high. If the P-wave is of usually long duration, it may represent atrial enlargement. Typically, a large right atrium gives a tall, peaked p-wave while a large left atrium gives a two- humped bifid p-wave.  **PR-Interval** The PR interval (PRI) represents the time it takes for the impulse to travel from the SA to the AV node. It represents the beginning of atria depolarization and the delay as the impulse travels through the AV node. It measures from the beginning of the P wave to the beginning of the QRS complex. It should measure 0.12 to 0.20 seconds (. i.e., between 3 to 5 small squares; anything above 5 small squares would be considered 1^st^ degree heart block). The PR interval is important to determine if there is a heart block or some other conduction problem. A long PRI could indicate a first degree heart C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG C:\\Users\\good.good-PC\\Pictures\\ECG\\Capturec.JPG **QRS Complex** The QRS complex represents the rapid depolarization of the right and left ventricles. Because the ventricles have a large muscle mass compared to the atria, the QRS complex usually has much larger amplitude than the P-wave. QRS complex is usually upright. However, it can be upside down (inverted) in leads VR and V1. If it is upside down in any other lead, there is likelihood of ischaemia or ventricular hypertrophy. Normal duration for the QRS complex is between 60 to 100ms (0.06 to 0.1s), or half of the PR interval. The amplitude of QRS complex ranges from 5 to 30 mm high (differs based on lead). If the QRS complex is wide (longer than 120ms), it suggests disruption in the heart conduction system such as LBBB (left bundle branch block), RBBB (right bundle branch block) or ventricular tachycardia. QRS complex is also wide in hyperkalaemia and in TCA (tricyclic antidepressant) overdose/toxicity e.g., imipramine overdosage. An unusually tall QRS complex may represent left ventricular hypertrophy. A very low-amplitude QRS complex may represent a pericardial effusion or infiltrative myocardial disease. **\ J-Point**  The J-point is the junction at which the QRS complex finishes and ST- segment begins. The appearance of a separate wave (J-wave also known as Osborn wave) at the J point is pathognomic of hypothermia or hypercalcemia. **ST- Segment** The ST- segment connects the QRS complex and the T wave. It represents end of ventricular conduction (depolarization) and beginning of ventricular recovery (repolarization). It has duration of 5 to 150ms (0.005 to 0.15s). Typical duration of ST-segment is around 0.80s. It is isoelectric (i.e., flat), but may be depressed or elevated with myocardial infarction or ischaemia. A prolonged ST- segment is seen in hypocalcaemia. ***ST- depression*** is also caused by digoxin, hypokalaemia and left ventricular hypertrophy. It is a reliable sign that myocardial injury has occurred. This could be caused by angina or non-Q wave infarction. With angina, ST segment returns to normal after the pain is relieved. With non-Q wave infarction, the ST segment remains down for at least 48 hours. The ECG changes seen with non-Q wave infarctions are T wave inversion and ST depression. Nitrates (e.g., Nitroglycerin) relieve the symptoms of angina and myocardial infarction (MI) but is contraindicated if a phosphodiesterase inhibitor (e.g., sildenafil, tadalafil, vardenafil, avanafil) was taken with 24 hours. s ***ST-elevation*** can also be caused by pericarditis or brugada syndrome. Reperfusion therapy improves survival in patients with ST-Elevation Myocardial Infarction (STEMI) and reduces patient's in-hospital and 30-day mortality rate.  *ST-Elevation Myocardial Infarction (STEMI)* **T-wave** T-wave represents the repolarization of the ventricles. It is generally upright and has a duration of 160ms (0.16s) (4 small boxes). Inverted T-wave can be a sign of myocardial ischaemia, hypokalemia or increased intracranial pressure, or metabolic abnormalities. It can also be caused by left ventricular hypertrophy. Peaked T- wave can be a sign of hyperkalaemia or very early myocardial infarction.  **QT- Interval** This is measured from the beginning of QRS complex to the end of T-wave. It measures time needed for ventricular depolarization and repolarization. Its duration should be less than 440ms (0.44s) \[acceptable range is 0.36 to 0.44 second\]. It varies with heart rate - the faster the heart rate, the shorter the QT interval, so it must be corrected to QTc (corrected QT interval) by dividing with square root of the PR interval. With regular rhythm, it shouldn\'t be greater than half of the distance between the two consecutive R waves. It also varies with age (increases progressively with age) and gender (higher in women).  A prolonged QTc is a risk factor for ventricular tachyarrythmias (*Torsedes de pointes*) and sudden death. It also indicates hypocalcaemia. An unusually short QTc can be seen in severe hypercalcaemia. **U-wave** The U-wave is hypothesized to be caused by the repolarization of the interventricular septum and the papillary muscles. It normally has low amplitude, and even more often completely absent. A very prominent U --wave may indicate hypokalaemia, hypercalcaemia or hyperthyroidism. **SINUS RHYTHM**  ***Normal Sinus Rhythm*** A picture containing shoji Description automatically generated ***Sinus tachycardia***  A picture containing fabric Description automatically generated ***Sinus Bradycardia*** The term sinus is synonymous with SA node. Normal sinus rhythm means that the SA node is the primary pacemaker. Sinus bradycardia or tachycardia means that SA node is under-firing or over-firing. In normal sinus rhythm, the impulse starts in the SA node. Atrial and ventricular rates are normal and between 60-100 beats per minute (bpm); Atrial and ventricular rhythms are regular; P waves are normal with each followed by QRS complex; PRI is within normal limit (WNL) between 0.12 -- 0.20 seconds; QRS is WNL between 0.06 -- 0.10 seconds. In sinus tachycardia, the rate is above 100 but less than 140. In sinus bradycardia, the rate is below 60. Sinus tachycardia can result from the following causes -- fever, hypovolemia, fear/anxiety, pain, exercise, and medications. For bradycardia, athletic and elderly people often have a heart rate slower than 60 bpm when they are sitting or lying down, and a heart rate less than 60 bpm is common for many people during sleep. Symptomatic bradycardia is the one that is of clinical importance and involves when the following symptoms are present -- hypotension, syncope/passing out, dizziness, weakness, confusion, heart palpitations/fluttering, feeling short of breath, chest pain and lack of energy. A bradycardia may result from the following causes - a problem with the SA node (sick sinus syndrome), a problem with the AV node or any of the electrical pathways through the heart (heart block), illness or medical problems (such as injury to the heart due to heart attack, endocarditis or a medical procedure, inflammation of the heart muscle, low thyroid function, electrolyte imbalance in the blood, sleep apnea, congenital heart defect, valvular heart disease, Lyme disease), certain medications, including beta blockers and heart rhythm medications. Atropine 1mg IV (repeat every 3-5 minutes -- a maximum of 3mg) is the drug of choice for treatment of symptomatic bradycardia. If atropine is ineffective, IV dopamine or IV Epinephrine (adrenaline) is used either alone or in combination with transcutaneous pacing. Tackling tachycardia or bradycardia involves treating the underlying cause(s). PR interval (PRI) is normal in sinus bradycardia (0.12 to 0.20s or 3 to 5 small boxes) unlike in first degree heart block where the PRI is greater than 0.20s. PRI is also normal in sinus tachycardia. **Sinus Arrest and Sinus pause:** Sinus Arrest or sinus pause occurs when there is a sudden absence of electrical activity initiated by the SA node. This results in a pause in the electrical activity seen on the tracing. In sinus arrest or sinus pause, there is no depolarization and contraction hence, a drop in blood pressure. In Sinus arrest or sinus pause, the underlying rhythm meets criteria for a sinus rhythm except for a missed beat/pause. The SA node fails to discharge an impulse in sinus arrest or sinus pause. While Sinus Arrest is defined as failure of the SA node to discharge an impulse for more than 2 seconds, Sinus Pause is defined as the failure of the SA node to discharge an impulse within less than 2 seconds. Sinus block (or sinus exit block) is another term that is interchangeably used for sinus arrest. Even though both has the same ECG rhythm pattern and similar symptoms such as bradycardia, fatigue, and syncope, they are not the same. Sinus arrest is due to the cessation of firing of SA node, whereas sinus block is due to the blockage of the electrical impulses generated by the SA node. Therefore, the difference is that in sinus arrest, the pathology is in the generation of electrical impulses but in sinus block, the pathology lies in transmission of impulse.  ***Sinus Arrest/block*** A picture containing shoji, building Description automatically generated ***Sinus Pause*** **Junctional Rhythms** Junctional rhythms are named such because their impulse originates from the AV node (AV junction) instead of the SA node. In junctional rhythm, rate is between 40-60 bpm. QRS duration is normal. R-R intervals are regular. P-wave is usually inverted (and can be absent) but occurs at the same rate as the QRS rate. PR interval is usually variable. Junctional rhythm is said to be accelerated if it extends above 60bpm.  ***Junctional Rhythm*** ***Accelerated Junctional Rhythm*** **Artifacts** They are distorted signals caused by a secondary internal or external source, such as muscle movement (shivering or tremor) or interference from an electrical device. It is a significant challenge in recognizing ECG changes as it confounds result. Other common sources of artifacts are loose electrodes and patient's cough. If Artifacts are occurring, there is interference seen between R-waves though the R-R intervals are regular C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG ***Artifact Vs. Normal Sinus Rhythm*** **Counting Heart Rate (Pulse) From ECG** (a). In a 6-second strip, calculate the number of QRS complex and multiply by 10 to get the Heart Rate (HR) for one minute. This method is preferable for irregular rhythms. (b). Count the number of large boxes between two R waves (QRS complex' peak) in a regular rhythm and  divide into 300. Alternatively count the number of small boxes between two R waves in a regular rhythm and divide into 1500. This method is preferable for a regular rhythm. Heart Rate = 300 ÷ Number of large boxes or 1500 ÷ Number of small boxes C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture2.JPG **DYSRHYTHMIAS AND THEIR CHARACTERISTIC ECG HALLMARKS** A dysrhythmia (interchangeably used with arrhythmia) is any problem with the rate or rhythm of the heartbeat. Rate refers to number of times the heart beats per minute. Rhythm refers to the pattern of regular or irregular pulses produced as the heart beats. A dysrhythmia can occur at any point along the conduction pathway or in the atria or ventricle. **Atria Dysrhythmias** - **Atrial Fibrillation (Afib):** Absent P-wave with "irregularly irregular" QRS complex is the hallmark of atrial fibrillation. R-R intervals are irregular. Many sites within the atria are generating their own electrical impulses, leading irregular conduction of impulses to the ventricles that generate heartbeat. This irregular rhythm can be felt when palpating a pulse.  A picture containing shoji Description automatically generated The atrial rhythm is not able to be measured as all atrial activity is chaotic. The atria are just quivering (at a rate of more than 350 bpm). This is the "jelly on the plate" Scenario -- wobble, wobble, but no contractions in the atria. The ventricular rhythm is irregular with no pattern to its irregularity. Atrial Fibrillation is commonly seen in congestive heart failure (CHF), coronary artery disease (CAD), rheumatic heart disease (RHD), hypertension (HTN) and Cor Pulmonale. It can also produce CHF, so rule out that the client has no prior CHF. If it is new hold exercise until medical evaluation or treatment. In Atrial Fibrillation, if the ventricular rate is below 100 bpm, the rhythm is said to be "controlled". If it is over 100 bpm, it is considered to have a "Rapid Ventricular Response". About 25% of atrial kick is lost leading to blood pooling and clot formation. ***Management of Atrial Fibrillation*** The initial management of atrial fibrillation is remembered with the mnemonic "SATE". S = Stabilize (monitor heart rate, blood pressure, respiratory status, and medication). A = Assess (Fluid and electrolyte status, medication management, risk factor identification and modification). T = Treat (arrhythmia management, reducing anxiety, anticoagulation management). E = Educate (disease process, anticoagulation teaching, prescribed medication). The 48 hours rule is used in the treatment of Afib. If you know when it started and it is less than 48 hours ago, it can be treated with medications or cardioversion. If not known or longer than 48 hours, control the rate, anticoagulate and do cardioversion for 6 weeks. - **Atrial Flutter:** A "saw tooth" pattern between QRS complexes is the hallmark of atrial flutter. The saw tooth pattern is known as F (flutter) wave. Atrial Flutter is also known as atrial tachycardia. P wave is absent and replaced with F wave at a ratio of 2 to 3 F waves to 1 QRS complex. Atral rate (the F wave rates) is about 200 to 300 per minute; the ventricular rate (Heart rate represented by the QRS waves) is between 100 to 140 bpm. PRI is not measurable; ventricular rate ("R" to "R" complexes) is regular. If the ventricular rate is less than 100, it is said to be controlled Atrial Flutter. If the ventricular rate is more than 100, it is said to be uncontrolled Atrial Flutter.  A picture containing chart Description automatically generated Atrial flutter has a "saw tooth" appearance similar to Atrial Fibrillation, but in the flutter the "R" to "R" complexes are regular. Atrial flutter and atrial fibrillation are both dysrhythmias resulting from impulses generated from multiple foci in the atria outside the AV node and SA node. The difference is that while the ventricular beat is fast and regular in flutter, it is fast and irregular in fibrillation. Treatment for both conditions are same (usually blood thinners, beta blockers and cardioversion). - **Premature Atrial Contractions (PACs)** They are common cardiac dysrhythmia characterized by premature beats originating in the atria. Part of the atria is contracting prematurely. They are also known as Atrial Premature Complexes (APCs) or Atrial Premature beats (APBs). Irregular ventricular rhythm (R-R interval), p-wave is discernable, rate is normal, can be regularly irregular. Caffeine, smoking and emotional stress. Patient is often asymptomatic, consider other cardiac issues. Treat with close monitoring. Can progress to atrial fibrillation.  **Ventricular Dysrhythmias** - **Ventricular Flutter:** Sine wave pattern of QRS complex is the hallmark of ventricular flutter. It is also known as ventricular tachycardia (vtach). There is no p wave, but there is a regular ventricular rhythm. Results from abnormal tissues (such as myocardial scars) in the ventricles generating a rapid regular heart rhythm through electrical reentry or abnormal automaticity. Poor cardiac output is usually associated with this rhythm thus causing the patient to go into cardiac arrest. Combination of broadening QRS complex and tall T --wave produces a sine wave pattern. This pattern is also seen in severe hyperkalaemia. Check your patient!! This is a lethal rhythm. They may or may not have a pulse. This rate can be counted on a rhythm strip. Patient may be stable but should not be left alone and the nurse should get immediate medical help. If patient becomes unstable that there is no cardiac output, it is called "Pulseless Ventricular flutter". Vtach can be monomorphic or polymorphic in shape. Monomorphic vtach has a constant pattern of sine wave while polymorphic vtach (also known as *Torsades de pointes* or "twisting of the points") has a variable party streamer outlook. Polymorphic vtach is usually seen in the setting of prolonged QT interval (above 440 miliseconds) and can degenerate rapidly to ventricular fibrillation (vfib). C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG Monomorphic V.tach  Polymorphic V.tach **Note:** Absent P -- wave with wide QRS complex (QRS duration ≥0.12 s) is the hallmark of all ventricular arrhythmias \[e.g., Ventricular tachycardia (monomorphic and polymorphic) and Ventricular fibrillation\]. - **Ventricular Fibrillation (vfib):** Absent P-wave with a rapid, bizarre, and chaotic wide QRS complex is the hallmark of ventricular fibrillation. The ventricles quiver rather than pump, which diminished blood pressure and flow. Disorganized electrical signals cause the ventricles to quiver instead of contract in a rhythmic fashion. A patient will be unconscious as blood is not pumped to the brain. C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG Ventricular Fibrillation is a lethal rhythm. If this is real and not artifact, your patient has no pulse and cannot be counted on a rhythm strip. Patient might have had acute Myocardial Infarction (MI), has severe heart disease, hyper/hypokalemia, hyper/hypocalcemia, or electrocution. Get immediate help; activate the emergency response. **Note:** Ventricular flutter and ventricular fibrillation are both ventricular dysrhythmias. The difference is that while the ventricular beat is fast and regular in flutter, it is fast and irregular in fibrillation. Ventricular flutter may manifest with or without pulse (stable vs unstable) but ventricular fibrillation only manifests without pulse and thus very deadly. Unstable ventricular flutter and ventricular fibrillation require immediate defibrillation. Defibrillation causes temporary asystole and stimulates the pacemaker to capture. A dose of Epinephrine (Adrenaline) 1mg IV (every 3-5 minutes) is given after the second shock. An antiarrhythmic drug (e.g., Amiodarone 300mg or Lidocaine 1-1.5mg/kg) is given after the third shock. Second dose of the antiarrhythmic drugs are decreased to Amiodarone 150mg or Lidocaine 0.5-0.75mg/kg. A vfib that does not respond to three or more standard defibrillation is termed refractory vfib. **Atrial Fibrillation vs. Ventricular Fibrillation**  **Atrial Flutter vs. Ventricular Flutter** C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG - **Asystole:** This indicates no electrical activity. Increase the gain on the monitor, check another lead. If this problem is truly asystole, there will be no pulse (no mechanical activity). Start CPR!!! Give Epinephrine (Epi) 1mg IV push every 3-5 minutes. Do not defibrillate. - **Pulseless Electrical Activity (PEA):** Electricity only; grid may even look like normal sinus rhythm but there will be no pulse; No mechanical activity (pump isn't working). Treat like asystole. Start CPR and give Epi 1mg IV push every 3-5 minutes. PEA with narrow QRS complexes usually results from mechanical problems such as cardiac tamponade, tension pneumothorax, mechanical hyperinflation, and pulmonary embolism. They lead to acute myocardial infarction (MI) resulting from myocardial rupture. PEA with wide QRS complexes usually results from metabolic problems such as severe hyperkalemia, sodium-channel blocker toxicity (e.g., carbamazepine, lacosamide, phenytoin toxicity). They lead to acute myocardial infarction (MI) resulting from pump failure.  - **Premature Ventricular Contractions (PVCs)** C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG ***Unifocal PVCs***  ***Multifocal PVCs*** This is also called premature ventricular complexes, ventricular premature beats or ventricular extrasystoles. They are extra (ventricular ectopic) heart beats that disrupt the regular heart rhythms. It is due to a part of the ventricle depolarizing earlier than it should. P wave is usually inverted or absent. They occur in many people and often cause few or no symptoms. Sensations usually felt include fluttering, pounding, or jumping, skipped beats, or missed beats, increased awareness of heartbeat. They do not have to be included in rate calculation because they do not produce a beat. Drank coffee today? You may have some of these feelings! Other causation factors include smoking, emotional stress, coronary artery disease (CAD), myocardial infarction (MI), mitral valve prolapse (MVP), cardiomyopathy, digitalis toxicity. In the ECG strip, two similar odd waveforms (showing ventricles depolarizing prematurely) are seen in unifocal PVCs; if they differ in appearance, they would be called multifocal PVCs The more frequent they are the more cardiac output are reduced. PVCs can worsen into ventricular tachycardia (flutter), if they occur more than 6 times in a minute, or three or more times in a row. Clients need to rest if there are changes in frequency or appearance -- monitor to see if return to baseline or decrease in frequency. ***Treatment of PVCs*** Chronic Asymptomatic clients may not need treatment. Client bothered by palpitation? Avoid stimulants, caffeine, nicotine/tobacco Frequent PVCs -- low dose beta blockers may reduce frequency as well as perception of palpitations. PVCs with MI may be precursor to more dangerous rhythms. ***Stable vs. Unstable Cardiac Clients*** Stable clients have minimal or no symptoms. Unstable clients have the following symptoms, namely, shortness of breath (SOB), chest pain, hypotension; diaphoretic, cold, clammy skin; change in level of conscious (LOC)/altered mental status, low oxygen saturation, pulselessness and coma. In stable condition, continue to serve client his/her medications. In unstable conditions, go straight to electricity (defibrillator, pace or synchronised cardioversion). **Supraventricular Tachycardia (SVT)** C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG  The impulses come from somewhere above the AV-node within the atria but not from the SA node. There is usually an anterograde electrical conduction from the atria to the AV node to the ventricles, with retrograde conduction via an accessory pathway from the ventricles back to the atria. This causes a rapid heart rate above 100bpm. It has a regular rhythm. Rate is usually between 140 to 220 bpm. P-wave is usually non-visible, rate is too fast. PR-interval is not applicable. QRS is narrow but within normal limit (WNL). It can be distinguished from sinus tachycardia (ST) in that ventricular rate is between 140 & 220 bpm (in ST rate is between 100 and 140 bpm) and PRI is absent (but in ST, PRI is present and WNL). It occurs in rheumatic heart disease (RHD), mitral valve prolapse (MVP), cor Pulmonale and digitalis toxicity. Client may have palpitations, anxiety, chest tightness, and dizziness. Nursing responsibility is to limit activity and medicate as appropriate. ***Treatment*** If unstable, institute cardioversion in addition to medications. If stable, continue with medications e.g., beta-blockers, calcium channel blockers (verapamil, diltiazem) and vagal maneuvers. Adenosine 6mg IV (followed by a normal saline flush) is drug of choice for converting supraventricular tachycardia to normal sinus rhythm. If unsuccessful a second dose of Adenosine is increased to12mg followed by a normal saline flush. **Sinus Tachycardia vs Supraventricular Tachycardia** C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG - **Strain vs Ischemia: How can I tell the difference?**  Both have ST depression. Down sloping depression of the ST segment of 1mm or more indicates myocardial ischemia. Strain never depresses the ST segment up to 1 mm. Ischemia can also cause ST elevation unlike strain. - **Heart Block** The normal electrical conduction through the heart starts at the sinoatrial (SA) node, which then travels to the surrounding atrial tissue to the atrioventricular (AV) node. At the AV node, the electrical signal is delayed between 120 to 200 milliseconds (. i.e., the PRI). Once through the AV node, the electrical signal travels through the His-Purkinje system, which distributes the electrical signal to the left and right bundles, and ultimately to the myocardium of the ventricles. The pause at the AV node (. i.e., the PRI) allows the atria to contract and empty before ventricular contraction. Heart block is an abnormal heart rhythm where the heart beats too slowly (bradycardia). It is an arrhythmia due to delay in conduction between atria and ventricle beyond normal limit (. i.e., above 200ms). In this condition, the electrical signals that stimulate the heart to contract are partially or totally blocked between the atria and ventricles. Heart block is classified as 1st, 2nd, 3^rd^ degree based on degree of severity. To enhance understanding of heart block in the ECG, we use the concept of a quarrelling husband and wife where P-wave is the wife and QRS-complex is the husband. ***Normal Sinus Rhythm*** C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG In Normal Sinus Rhythm, the wife (P wave) waits at home every night for the husband (QRS complex). The husband comes home on time every night. ***First Degree Heart Block***  In first degree AV Block, the wife (P wave) is waiting at home. The husband (QRS complex) comes home late every night, but he always comes home, and it is the same time every night.The electrical impulse begins in the SA node then is delayed in the AV node longer than normal due to partial block and lastly conducts normally through the ventricles. Rhythm: Atrial and ventricular rhythm are regular. Rate: Atrial and ventricular rate are the same; PRI: prolonged, greater than 0.20 (5 small squares), but constant. QRS: usually normal. The first degree A-V block is the most common conduction disturbance. It occurs in in healthy and diseased hearts. It can be caused by myocardial infarction, digitalis toxcity, myocarditis and hyperkalemia. Nursing responsibility is to treat the underlying cause and observe for progression to a more advanced A-V block. ***Second Degree Heart Block Type 1 (Wenkeback A-V block or Mobitz 1)*** The wife (P wave) is waiting at home. The husband (QRS complex) comes home later and later every night, until one night he doesn't come home at all. The Husband (QRS complex) must come home at least two nights in a row to see this pattern. This represents ischemia and is reversible. The heart rate tends to be slower as some beats are missed. The PRI (PR Interval) progressively elongates until a QRS complex is missed, then shortens again as the cycle repeats. Here the impulse starts in the SA node but the AV node holds the impulse progressively longer. C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG  A picture containing wire Description automatically generated ***Second Degree AV Block Type 2 (Mobitz ii A-V block)*** ***(Constant/Periodic)***   The wife (P wave) is waiting at home. Sometimes the husband (QRS complex) comes home, sometimes he doesn't. When he does come home, it is always at the same time. Note: This is usually more serious than type 1 and will sometimes require counseling (in the form of temporary or permanent pacemaker). Here electrical excitation sometimes fails to pass through the A V node or bundle of His. Electrical conduction usually has a constant PR interval. Atrial contractions are not regularly followed by ventricular contraction. This represents injury and is not reversible. This may progress rapidly and without warning to third degree heart block (complete heart block) or asystole. Here the impulse starts in the SA node and travels to the AV node as usual, but then either intermittently or in a constant pattern a complete block occurs below the AV node stopping conduction to the ventricles. ***Third Degree Heart Block (Complete AV Block).*** The wife (P wave) is no longer waiting at home. She and her husband (QRS complex) are now on separate schedules, have no relationship, and are no longer talking. Each spouse has a regular, individual schedule. Here impulse is completely blocked with each beat between the SA node and AV node. There are more Ps than QRS complexes. Atrial contractions are normal, but no electrical conduction is conveyed to the ventricles. The ventricles generate their own signal through an 'escape mechanism' from a focus somewhere within the ventricle. The ventricular escape beats are usually slow, hence more Ps than QRS complexes. Only P and QRS complex are present because the impulse transmission pattern that generate the fundamental ECG waveform is lost as the impulse is completely blocked at the AV-junction leading to atria and ventricle generating their impulses independently. Note: This frequently requires counseling in the form of temporary or permanent pacemaker. Both atria and ventricles are firing regularly but are not in "sync" (. i.e., do not relate to each other). This can progress rapidly to asystole without warning, so the nurse needs to have an external pacemaker nearby. Transcutaneous pacing is indicated in heart block. C:\\Users\\GOODLUCK NSHI\\Desktop\\Capture.JPG A picture containing building Description automatically generated ***Bundle Branch Block*** Abnormal conduction through the bundle branches will cause a depolarization delay through the ventricular muscle, this delay shows as a widening of the QRS complex. Right Bundle Branch Block (RBBB) indicates a problem in the right side of the heart, whereas Left Bundle Branch Block (LBBB) indicates a problem with the entire heart.  **STEPS IN ECG INTERPRETATION** Rhythm -- atrial or ventricular? Rate -- atrial or ventricular? Are P's and QRS's married? Intervals -- PRI, QRS. Any funny beats? Are there any early or premature beats? After measurement, look back at the strip. **PACING** Pacing involves use of pacemaker to enhance the electrical activity of the heart. A permanent pacemaker may be indicated for conditions such as: Symptomatic bradycardia (e.g., sinus node dysfunction, AV node dysfunction), Pacing for specific conditions (such as cardiac transplantation, neuromuscular diseases, sleep apnea syndrome, cardiac sarcoidosis), prevention and termination of arrhythmias (such as antitachycardia pacing (ATP), long QT syndrome) and pacing for hemodynamic indications (such as cardiac resynchronization therapy). Pacing can be atrial, ventricular, or dual (atrioventricular). **Atria Pacing:** In atrial pacing, the pacemaker lead is conventionally placed in the right atria. Pacemaker generator fires an impulse to initiate atrial activity. Atrial and ventricular rhythms are regular. Atrial and ventricular rate are same. An atrial paced rhythm would have a pacer spike before the P wave only. The P wave may appear normal or abnormal, but the QRS complex will appear normal. PRI is within normal limit (WNL). C:\\Users\\good.good-PC\\Pictures\\ECG\\PACING\\Capture5.JPG **Ventricular Pacing:** The pacemaker lead is placed into the right ventricle. The right ventricle will contract first followed by the left ventricle. This results to a wide QRS complex. Atrial activity is typically absent although can be present at times. Atrial rhythm, rate and PRI are non-measurable. A ventricular paced rhythm would only have a pacer spike prior to a wide QRS complex. Impulses are generated in only one ventricle (typically the right ventricle). **Ventricular Pacing**  **Atrioventricular Pacing:** An atrioventricular pacemaker (also known as sequential or dual chamber oacemaker) paces the right atrium and right ventricle in sequence. One pacemaker lead is placed in the right atria, and another is placed into the right ventricle. The pacemaker generator fires an impulse to the atria and to the ventricle sequentially causing atrial then ventricular contraction. Two pacer spikes are visible on the ECG, one prior to the P wave and the other prior to the QRS complex. Atrial and ventricular rhythm are regular. Atrioventricular pacemakers improve cardiac synchrony between the atria and ventricles. **Biventricular Pacing:** A biventricular pacemaker (also known as sequential biventricular pacemaker) is a special type of pacemaker that paces both sides of the lower chambers of the heart (the right and left ventricles) to help treat heart failure. This type of pacing is called \"biventricular pacing,\" and the therapy provided by biventricular pacing is called cardiac resynchronization therapy. Two ventricular pacing spikes may be seen on the ECG, and one spike may appear after the beginning of the QRS complex. Atrial activity is typically absent. **Biventricular Pacing**  **Demand Pacing:** Demand Pacemakers are the most common type of implanted pacemaker. The Demand Pacemaker sends an electrical (pacer spike) only if the pacemaker does not sense an intrinsic heartbeat occurring at the programmed threshold rate (e.g., 40 b/min). C:\\Users\\good.good-PC\\Pictures\\ECG\\PACING\\Capture3.JPG **PACER MALFUNCTIONS** Pacer malfunctions mostly occurs as failure to pace or failure to capture. ***Failure to Pace*** This is absence of pacer activity (spikes) when the pacemaker generator should have fired an impulse. Typically seen when the patient's intrinsic heart rate falls less than the pacemaker's low heart rate limit (threshold) and the pacer fails to fire. Can result from battery or power problems.  ***Failure to Capture*** Here the Pacer spike is not followed by the appropriate atrial or ventricular response. Can be a potentially lethal situation and usually result from worsening cardiac situation than from pacemaker battery or power. **Failure to Capture** **TELEMETRY** Telemetry is an observation tool that allows continuous ECG, heart rate (HR) and oxygen saturation (SPO2) monitoring while patient remains active without the restriction of being attached to a bedside cardiac monitor. Telemetry is done with Holter monitor also known as Telemetry monitor. The readings of the monitor are displayed on a screen at a remote location, classically a nursing station in a special ward and in a monitored telemetry hub. The leads of the monitor are colour-coded and include the following colours: green, red, white, black, and brown.  The mnemonics to remember where to place each lead is "Smoke over fire, Snow over Grass, Chocolate is sweet to the heart" Smoke is **black** in colour and represents the black lead, Fire is **red** in colour and represents the red lead. A burning fire (red) produces smoke (black) above itself (smoke over fire). "B**l**ack has an "L" and goes to the **l**eft". Snow is **white** in colour and falls on **green** grass (snow over grass). Snow represents the **white** lead; grass is green and represents the **green** lead. "White rhymes with right and goes on the right". "Chocolate is sweat to the heart". Chocolate is brown in colour and represents the **brown** lead. The brown lead is placed at the centre close to the heart. The black lead is placed above the red lead on the left side; white lead is placed above green lead on the right side and the brown lead stays at the centre (close to the heart). **QUESTIONS** 1. A nurse performs an assessment on a client who has a diagnosis of atrial fibrillation. The nurse checks for a characteristic of atrial fibrillation by: a). Auscultating the apical pulse for an irregular rate while palpating the radial pulse for a pulse deficit. b). Palpating the radial pulse for quality while auscultating the apical pulse volume c). Auscultating the apical pulse for a regular pulse while palpating the radial pulse for quality d). Palpating the radial pulse for quality while auscultating the apical pulse for an irregular rate **Correct** **a). Auscultating the apical pulse for an irregular rate while palpating the radial pulse for a pulse deficit.** When a pulse rate is irregular, the apical pulse should be auscultated for irregularity, and the radial pulse should be palpated for the pulse deficit. Pulse deficit is a difference between the apical rate and the radial pulse rate, which is a characteristic of atrial fibrillation. 2. A client has a slow, regular pulse. On the monitor, the nurse notes regular QRS complexes with no p waves and a ventricular rate of 50 beats per minute. The nurse suspects that there is a problem at which part of the cardiac conduction system? a). The left ventricle b). The bundle of His c). The sinoatrial (SA) node d). The atrioventricular (AV) node **Correct** **C. The sinoatrial (SA) node** A normal P wave indicates that the impulse that depolarized the atrium was initiated in the SA node. A change in the form of P wave (inverted P wave or absence of a P wave) can indicate a problem at this part of the conduction system, with the resulting impulse originating from an alternate lower site in the cardiac conduction pathway. 3. A client remains in atrial fibrillation with rapid ventricular response despite pharmacological intervention. Synchronous cardioversion is scheduled to convert the rapid rhythm. The nurse plans to implement which important action to ensure safety and prevent complications of the procedure? a). Cardiovert the client at 360 joules b). Sedate the client before cardioversion c). Ensure that emergency equipment are available d). Ensure that the defibrillator is set on the synchronous mode. **Correct.** **d). Ensure that the defibrillator is set on the synchronous mode.** Cardioversion is similar to defibrillation with two major exceptions (1) the countershock is synchronized to occur during ventricular depolarization (QRS complex), and (2) less energy is used for the countershock. The rationale for delivering the shock during QRS complex is to prevent the shock from being delivered during repolarization (T wave), often termed the "vulnerable period". If the shock is delivered during this period, the resulting complication is ventricular fibrillation. It is crucial that the defibrillator is set on the "synchronous" mode for a successful cardioversion. Cardioversion usually begins with 50 to 100 joules. 4. A nurse should expect a client experiencing an acute myocardial infarction to first manifest which pattern on the electrocardiogram? a). An abnormal Q wave b). ST segment elevation c). T wave elevation d). Absent P waves **Correct** **b). ST segment elevation** ST segment elevation or depression usually occurs immediately or during the early stages of acute myocardial infarction. T wave inversion and abnormal Q wave changes occur later, within hours to several days after the acute myocardial infarction. Absent P wave or p waves that are difficult to discern are noted in atrial fibrillation, atrial flutter, ventricular fibrillation, and ventricular flutter. 5.  Which of these rhythm strips would be interpreted as normal sinus rhythm? a). Rhythm A b). Rhythm B c\) Rhythm C d\) Rhythm D **Correct** **c) Rhythm C.** The heart rate on this rhythm strip is 68 beats/minute, the P and T waves are normal, the PR interval is 0.16 second, the QRS complex is 0.08 second, and the QT interval is 0.40 second. All components are regular and within normal limits; therefore, this strip can be interpreted as normal sinus rhythm. -- -- -- -- -- -- 6. The QRS complex represents: a). the time needed for ventricular depolarization and repolarization. b). conduction of an electrical impulse that originates in the SA node and travels through the atria. c). the relative refractory period of repolarization (ventricular recovery). d). depolarization of and impulse conduction through the ventricles. **Correct** **d). depolarization of and impulse conduction through the ventricles.** 7. Which statement most accurately describes the PR interval? a). It represents ventricular depolarization and contraction (ventricular systole). b). It is evaluated together with the amplitude, configuration, and deflection. c). It usually ranges from 0.12 to 0.20 second. d). It extends from the end of the P wave to the beginning of the QRS complex. **Correct** **c). It usually ranges from 0.12 to 0.20 second.** The normal PR interval ranges from 0.12 to 0.20 second. The QRS complex not the PR interval represents ventricular depolarization and contraction (ventricular systole). Only the length of the PR interval is measured; the amplitude, configuration, and deflection of a PR interval are not evaluated. The PR interval extends from the beginning (not the end) of the P wave to the beginning of the QRS complex. 8. What\'s the correct QRS complex measurement for the rhythm strip shown here?https://competency.lww.com/ccu/units/CC00030/cetest/media/posttest03q4.jpg a). 0.44 second b). 0.16 second c). 0.50 second d). 0.08 second **Correct** **d). 0.08 second.**  The QRS complex (following the PR interval and measured from the beginning of the Q wave to the end of the S wave) shown here measures 0.08 second. 9. Which of the following is lost when a person has atrial fibrillation? a). Ventricular diastole b). Atrial filling c). Ventricular premature beats d). Atrial kick **Correct** **d). Atrial kick** In atrial fibrillation, the atria quiver and ineffectively contract; atrial kick is the contraction of the atria. The right atrium receives blood from the superior and inferior vena cava, and the left atrium receives blood from the lungs. During ventricular diastole the ventricles are relaxed and filling with blood; atrial fibrillation does not stop this from occurring. Atrial fibrillation is not a cause of premature ventricular beats. 10. This rhythm strip shows sinus tachycardia with premature ventricular contractions (PVCs) leading to which rhythm?  a). Ventricular tachycardia b). Torsades de pointes c). Accelerated idioventricular rhythm d). Ventricular fibrillation **Correct** **d). Ventricular fibrillation** The correct interpretation of this rhythm is sinus tachycardia with PVC leading to ventricular fibrillation. Torsades de pointes, a special variation of polymorphic ventricular tachycardia, has a rapid ventricular rate of 150 to 300 beats/minute. It\'s characterized by a prolonged QT interval and QRS polarity that seems to spiral around the isoelectric line. An accelerated idioventricular rhythm has a rate that\'s under 100 beats/minute but exceeds 40 beats/minute. In ventricular tachycardia, three or more PVCs occur in a row. The ventricular rate exceeds 100 beats/minute but is typically less than 250 beats/minute. 11. Why is ventricular fibrillation clinically significant? a). The rhythm acts as a safety mechanism to prevent asystole. b). The fibrillatory waves are fine rather than coarse. c). Atrial depolarization occurs in a chaotic manner. d). There is no cardiac output. **Correct** **d). There is no cardiac output.** No effective depolarization occurs in ventricular fibrillation, so there is no cardiac output or pulse. Untreated ventricular fibrillation leads to ventricular standstill and death. Impulses arise from multiple ectopic pacemakers in the ventricles, resulting in a chaotic pattern of electrical activity. No atrial depolarization occurs in ventricular arrhythmias. An idioventricular rhythm acts as a safety mechanism to prevent asystole. Fine and coarse types of ventricular fibrillation produce no cardiac output. 12. Given the following information about this rhythm strip, what\'s the correct interpretation of the rhythm shown here?\ \ Rhythm: Chaotic\ Rate: Greater than 300 beats/minute\ P wave: Indiscernible\ PR interval: Not measurable\ QRS complex: Abnormal\ T wave: Indiscernible\ QT interval: Not measurable\ Other: Complex size increases and decreaseshttps://competency.lww.com/ccu/units/CC00033/cetest/media/posttest06q3.jpg a). Torsades de pointes b). Ventricular fibrillation c). Ventricular asystole d). Ventricular tachycardia **Correct** **a). Torsades de pointes** The correct interpretation of the rhythm shown here is torsades de pointes. Ventricular asystole (asystole or ventricular standstill) is the absence of discernible electrical activity in the ventricles. Ventricular fibrillation is a chaotic pattern of electrical activity in which impulses arise from multiple ectopic pacemakers in the ventricles. This causes the ventricles to quiver, producing no effective muscular contraction and no cardiac output. In ventricular tachycardia, three or more PVCs occur in a row. The ventricular rate exceeds 100 beats/minute but is typically less than 250 beats/minute. 13. In this rhythm strip, what rhythm is shown leading into ventricular fibrillation? a). Ventricular tachycardia b\) Coarse-waved ventricular fibrillation c). Accelerated idioventricular rhythm d). Torsades de pointes **Correct.** **a). Ventricular tachycardia** This rhythm strip shows ventricular tachycardia leading into ventricular fibrillation. Coarse-waved ventricular fibrillation, accelerated idioventricular rhythm, or torsades de pointes are not present. Coarse-waved ventricular fibrillation is characterized by a chaotic pattern of electrical activity and pacemakers in the ventricles producing larger fibrillatory waves. An accelerated idioventricular rhythm is characterized by enhanced automaticity of ventricular tissue and a rate of 40 to 100 beats/minute. Torsades de pointes is a special variation of polymorphic ventricular tachycardia, with a rapid ventricular rate that varies between 150 and 300 beats/minute. It\'s characterized by a prolonged QT interval and QRS polarity that seems to spiral around the isoelectric line. The QRS complexes gradually change back and forth, with the amplitude of each successive complex gradually increasing and decreasing, resulting in a spindle-shaped rhythm. 14. What is the correct interpretation of the rhythm shown here, given the following information?\ \ *Rhythm*: Irregular\ *Rate*: 50 beats/minute\ *P wave*: Normal\ *PR interval*: Variable\ *QRS complex*: 0.06 second\ *T wave*: Normal\ *QT interval*: 0.28 second\ *Other*: PR interval increases until dropped beathttps://competency.lww.com/ccu/units/CC00034/cetest/media/posttest07q4.jpg a). Complete AV dissociation b). Type 1 second-degree AV block c). Type 2 second-degree AV block d). Third degree AV block **Correct** **b). Type 1 second-degree AV block** The correct interpretation of the rhythm strip shown here is type 1 second-degree AV block (Wenkeback A-V block or Mobitz 1). The PRI (PR Interval) elongates until a QRS complex is missed, then shortens again as the cycle repeats. 15. A nurse in a telemetry unit observed the rhythm strip shown below in a patient. What is the correct interpretation of the strip?  a). Ventricular pacing b). Atrial pacing c). Dual Chamber pacing d). Third degree AV block **Correct** **b). Atrial pacing.** An atrial paced rhythm would have a pacer spike before the P wave only. The P wave may appear normal or abnormal, but the QRS complex will appear normal. **References** Aehlert, B. (2013). *ECGs made easy (5th ed.)* Elsevier Mosby. Baltazar, R. (2009). *Basic and bedside electrocardiography.* Lippincott Williams & Wilkins. Coviello, J. (Ed.). (2016). *ECG interpretation made incredibly easy (6th ed.)*. Lippincott Williams & Wilkins. ECG & ECHO Learning (2020). *Clinical ECG Interpretation.* Https://www.ecgwaves.com/topic/sinoatrial-arrest-sinoatrial-pause-sinus ECGMedicalTraining.Com. (2015). *The Basics of Paced Rhythms.*. Heart Rhythm Society. (2018). *Heart Block.* Available https//www.hrsonline.org/.../Heart.../Hea... Hall, P,J. & Guyton, A.C. (2016). *Guyton and Hall textbook of medical physiology.* 12^th^ Ed. Elsevier, **Hinkle**, **J.L., & Cheever**, **K.H. (2014).*** Brunner & Suddarth\'s Textbook of Medical-Surgical Nursing , 13th ed.* Lippincott Williams & Wilkins Huff, J. (2012). *ECG workout (6th ed.)*. Lippincott Williams & Wilkins. Lee, B. K., & Kowey, P. R. (2014). *Supraventricular tachycardias. In: M.H. Crawford (Ed.), CURRENT diagnosis and treatment: Cardiology (4th ed.).* McGraw Hill. NCLEX Ultimate APP. (2017). *ADULT HEALTH: Cardiovascular.* V.1.4 The University of Toledo Medical Center. (n.d). Advanced EKG Refresher.https://utmc.utoledo.edu/depts/nursing/pdfs/Advanced%20EKG%20Refresher.pdf Wikipedia. (2017). *Electrocardiography.* Woods, S., et al. (2010). *Cardiac nursing (6th ed.).* Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins. Zerwekh, J. (2015). *Illustrated Study Guide for The NCLEX-RN EXAM.* Evolve, Elsevier