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Questions and Answers
Cardiac dysrhythmias, also known as ______, are abnormalities in the heart's rhythm.
Cardiac dysrhythmias, also known as ______, are abnormalities in the heart's rhythm.
arrhythmias
Cardiac dysrhythmias only affect the rate of heartbeats but not the conduction pathways.
Cardiac dysrhythmias only affect the rate of heartbeats but not the conduction pathways.
False (B)
Which of the following is NOT a significant reason for addressing cardiac dysrhythmias?
Which of the following is NOT a significant reason for addressing cardiac dysrhythmias?
Name the three types of depolarizing mechanisms that can initiate dysrhythmias.
Name the three types of depolarizing mechanisms that can initiate dysrhythmias.
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Match the following dysrhythmia mechanisms with their descriptions:
Match the following dysrhythmia mechanisms with their descriptions:
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What is the primary consequence of failure to repolarize to normal resting membrane potential?
What is the primary consequence of failure to repolarize to normal resting membrane potential?
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Triggered activity always occurs during phase 3 of the action potential.
Triggered activity always occurs during phase 3 of the action potential.
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What is the role of the sarcoplasmic reticulum in late triggered activity?
What is the role of the sarcoplasmic reticulum in late triggered activity?
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Reentry is associated with most ______.
Reentry is associated with most ______.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Which of the following conditions can predispose to reentry?
Which of the following conditions can predispose to reentry?
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Reentry can only occur in one direction in the heart.
Reentry can only occur in one direction in the heart.
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How can ECG recordings aid in dysrhythmia analysis?
How can ECG recordings aid in dysrhythmia analysis?
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What condition is characterized by no apparent association between atrial and ventricular conduction?
What condition is characterized by no apparent association between atrial and ventricular conduction?
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Accessory pathways are always acquired abnormalities in the cardiac conduction system.
Accessory pathways are always acquired abnormalities in the cardiac conduction system.
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What is the consequence of early ventricular depolarization due to alternative pathways?
What is the consequence of early ventricular depolarization due to alternative pathways?
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The right bundle branch supplies the ______.
The right bundle branch supplies the ______.
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What characterizes premature ventricular complexes (PVCs)?
What characterizes premature ventricular complexes (PVCs)?
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Supraventricular tachycardia exclusively refers to atrial tachycardia.
Supraventricular tachycardia exclusively refers to atrial tachycardia.
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What is the rate of ventricular tachycardia in beats per minute?
What is the rate of ventricular tachycardia in beats per minute?
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In bigeminy, PVCs occur every _____ beat.
In bigeminy, PVCs occur every _____ beat.
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Match the terms with their definitions:
Match the terms with their definitions:
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Which of the following features is associated with ventricular tachycardia?
Which of the following features is associated with ventricular tachycardia?
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Compensatory pauses are common with premature ventricular complexes.
Compensatory pauses are common with premature ventricular complexes.
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What is a common consequence of high-frequency PVCs?
What is a common consequence of high-frequency PVCs?
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What is a characteristic of junctional escape rhythm?
What is a characteristic of junctional escape rhythm?
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Ventricular escape rhythm occurs at a rate of 40 to 60 beats/min.
Ventricular escape rhythm occurs at a rate of 40 to 60 beats/min.
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What condition allows a slower pacemaker to take over in heart rhythms?
What condition allows a slower pacemaker to take over in heart rhythms?
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Atrial dysrhythmias often involve _____ complexes that occur earlier than normal.
Atrial dysrhythmias often involve _____ complexes that occur earlier than normal.
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Match the dysrhythmias with their respective origins and characteristics:
Match the dysrhythmias with their respective origins and characteristics:
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Which of the following conditions can cause cardiac impulse initiation at an abnormal site?
Which of the following conditions can cause cardiac impulse initiation at an abnormal site?
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Premature atrial complexes are characterized by abnormal or absent P waves.
Premature atrial complexes are characterized by abnormal or absent P waves.
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Define the term 'escape rhythm' in cardiovascular terms.
Define the term 'escape rhythm' in cardiovascular terms.
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What is atrioventricular block?
What is atrioventricular block?
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First-degree atrioventricular block usually requires treatment.
First-degree atrioventricular block usually requires treatment.
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What is a characteristic of Type I second-degree block?
What is a characteristic of Type I second-degree block?
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Third-degree atrioventricular block is described as __________.
Third-degree atrioventricular block is described as __________.
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Which type of second-degree block is more serious due to its tendency to progress to complete AV block?
Which type of second-degree block is more serious due to its tendency to progress to complete AV block?
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What is a common cause of Type I second-degree block?
What is a common cause of Type I second-degree block?
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Match the type of block with its characteristic:
Match the type of block with its characteristic:
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What is the role of the AV node in heart conduction?
What is the role of the AV node in heart conduction?
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Flashcards
Cardiac Dysrhythmias
Cardiac Dysrhythmias
Abnormalities in the rhythm of impulse generation or conduction in the heart.
Types of Cardiac Dysrhythmias
Types of Cardiac Dysrhythmias
Includes abnormal sites of impulse initiation, abnormal rates of sinus rhythm, and disturbances in conduction pathways.
Ectopic Impulse Generation
Ectopic Impulse Generation
Impulse generation from an abnormal site rather than the normal pacemaker.
Mechanisms of Dysrhythmias
Mechanisms of Dysrhythmias
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Consequences of Dysrhythmias
Consequences of Dysrhythmias
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Junctional Premature Beats
Junctional Premature Beats
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Supraventricular Tachycardia
Supraventricular Tachycardia
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Premature Ventricular Complexes (PVCs)
Premature Ventricular Complexes (PVCs)
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Bizarre QRS
Bizarre QRS
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Compensatory Pause
Compensatory Pause
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Bigeminy
Bigeminy
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Ventricular Tachycardia
Ventricular Tachycardia
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Wide QRS Complexes
Wide QRS Complexes
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Abnormal Site of Impulse Initiation
Abnormal Site of Impulse Initiation
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Escape Rhythm
Escape Rhythm
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Junctional Escape Rhythm
Junctional Escape Rhythm
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Ventricular Escape Rhythm
Ventricular Escape Rhythm
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Premature Atrial Complexes (PACs)
Premature Atrial Complexes (PACs)
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Reentrant Circuits
Reentrant Circuits
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Enhanced Excitability
Enhanced Excitability
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Triggered Activity
Triggered Activity
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Atrioventricular block
Atrioventricular block
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First-degree block
First-degree block
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Second-degree block
Second-degree block
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Type I Second-degree block
Type I Second-degree block
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Type II Second-degree block
Type II Second-degree block
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Third-degree block
Third-degree block
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AV Node Ischemia
AV Node Ischemia
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Bundle of His
Bundle of His
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Automaticity
Automaticity
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Reentry
Reentry
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Tachydysrhythmias
Tachydysrhythmias
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Myocardial Ischemia
Myocardial Ischemia
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ECG Analysis
ECG Analysis
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Phase 3 (Repolarization)
Phase 3 (Repolarization)
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Phase 4 (Late/Delayed Activity)
Phase 4 (Late/Delayed Activity)
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Third-degree heart block
Third-degree heart block
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Accessory pathways
Accessory pathways
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Wolff-Parkinson-White syndrome
Wolff-Parkinson-White syndrome
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Bundle branch block
Bundle branch block
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Intraventricular conduction defects
Intraventricular conduction defects
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Study Notes
Heart Failure
- Inability of the heart to maintain sufficient cardiac output to meet the metabolic demands of tissues and organs.
- Results in congestion of blood flow in the systemic or pulmonary venous circulation.
- Inability to increase cardiac output to meet the demands of activity or increased tissue metabolism.
- Increasing incidence; most common reason for hospitalization in those >65 years of age.
Heart Failure (Pathogenesis and Diagnosis)
- Heart failure (HF) is a potential consequence of most cardiac disorders.
- Most common cause is myocardial ischemia followed by hypertension and dilated cardiomyopathy.
- Common manifestations include dyspnea, pulmonary rales, cardiomegaly, pulmonary edema, S3 heart sound, and tachycardia.
- Results from impaired ability of myocardial fibers to contract, relax, or both.
Heart Failure (Systolic Dysfunction)
- MI is a common etiology.
- Reduced contractility evidenced by low ejection fraction and reduced inotropy during ventricular systole.
- Impaired contractility involves loss of cardiac muscle cells, β-receptor down-regulation, and reduced ATP production.
Heart Failure (Diastolic Dysfunction)
- Coronary artery disease and hypertension are two main causes.
- More likely to develop in elderly, in women, and in those without history of MI.
- Disorder of myocardial relaxation, excessively noncompliant ventricle does not fill effectively.
- Low cardiac output, congestion, and edema formation with normal ejection fraction.
Heart Failure (Compensatory Mechanisms and Remodeling)
- Helpful in restoring cardiac output toward normal.
- Over the long term are detrimental to the heart.
- Increased preload
- Myocardial hypertrophy
Heart Failure (Cont.)
- Sympathetic Nervous System Activation: Primarily a result of baroreceptor reflex stimulation (detects fall in pressure). CNS increases activity in the sympathetic nerves to the heart resulting in venoconstriction.
- Juxtaglomerular cells release renin, activating the RAAS cascade, resulting in increased sodium and water retention.
- Remodeling: process of myocyte loss, hypertrophy of remaining cells, interstitial fibrosis
- Increased preload
- Decreased CO to the kidney
- Reduced glomerular filtration = fluid conservation
- Frank-Starling Mechanism
Heart Failure (Myocardial Hypertrophy and Remodeling)
- Chronic elevation of myocardial wall tension (law of Laplace).
- High systolic pressure in the ventricle needed to overcome high afterload, leading to hypertrophy.
- Neurohormonal factors have hypertrophic effect on the heart.
- Angiotensin II involved in remodeling
Heart Failure (Clinical Manifestations)
- Left ventricular failure most common.
- Often leads to right ventricular failure.
- Forward failure = insufficient cardiac pumping manifested by poor CO.
- Backward failure = congestion of blood behind the pumping chamber.
Left-Sided Heart Failure
- Backward effects result in accumulation of blood in pulmonary circulation, pulmonary congestion, and edema.
- Dyspnea, dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea.
- Cough, respiratory crackles (rales), hypoxemia, and high left atrial pressure, cyanosis.
- Forward effects result in insufficient CO with diminished delivery of.
- Acute cardiogenic pulmonary edema: life-threatening condition.
Right-Sided Heart Failure
- Pulmonary disorders—increased pulmonary vascular resistance-high afterload-right ventricular hypertrophy (cor pulmonale)-right ventricular failure.
- Backward effects caused by congestion in the systemic venous system (Edema, ascites, jugular veins distended, impaired mental functioning, hepatomegaly, splenomegaly, hepatobililary reflux test.).
- Forward effects cause low output to left ventricle leading to low CO.
Biventricular Heart Failure
- Most often result of primary left-sided HF progressing to right-sided HF.
- Reduced CO.
- Pulmonary congestion caused by left-sided HF.
- Systemic venous congestion caused by right-sided HF.
Class and Stage of Heart Failure
- FACES (fatigue, activity limitation, congestion, edema, shortness of breath).
- Diagnostic assessment includes x-ray and echocardiography.
- B-type natriuretic peptide level.
- Severity of symptoms used to identify the 4 classes/stages of HF
- Determine prognosis, therapy, monitoring.
Heart Failure (Treatment)
- Aimed at improving CO while minimizing congestive symptoms and cardiac workload.
- Obtained by manipulating preload, afterload, and contractility.
- Reduce preload-reduces intravascular volume with diuretics and ACE inhibitors, modify fluid and salt intake.
Heart Failure (Treatment - Cont.)
- Improve CO-digitalis.
- Inhibit SNS effects-β-blockers.
- Improve contractility-digitalis or other cardiac glycoside, β agonists (not for long-term use).
- Reduce effects of Ang II-ACE inhibitors and ARBs.
- Pacemakers: synchronize ventricular contraction.
Cardiac Dysrhythmias
- Also called arrhythmias; abnormality of the cardiac rhythm of impulse generation or conduction.
- Three major types: abnormal rates of sinus rhythm, abnormal sites (ectopic) of impulse initiation, disturbances in conduction pathways.
- Dysrhythmias are significant for two reasons: for indicating an underlying pathophysiologic disorder and for impairing normal CO.
Cardiac Dysrhythmias (Mechanisms)
- Impulse generation: abnormalities in rate of impulse generation from a normal pacemaker or from impulse generation from an abnormal (ectopic) site.
- Dysrhythmias initiated by three types of depolarizing mechanisms: Abnormal automaticity, Triggered activity from depolarization, Reentrant circuits.
Cardiac Dysrhythmias (Automaticity)
- Spontaneous generation of an action potential.
- Major causes: failure to repolarize to normal resting membrane potential, plasma membrane leakiness to sodium or calcium ions at rest, Hypokalemia.
Cardiac Dysrhythmias (Triggered Activity)
- Occurs when an impulse is generated during or just after repolarization.
- Results from depolarizing oscillation of the membrane potential.
- Early occurs in phase 3: allows some of the voltage-gated calcium channels to reopen and trigger another impulse.
- Late/delayed occurs in phase 4: Calcium ions spontaneously released from the sarcoplasmic reticulum after repolarization, resulting in an action potential.
Cardiac Dysrhythmias (Reentry)
- Associated with most tachydysrhythmias.
- Cardiac impulse continues to depolarize in a part of the heart after the main impulse has finished its path and the majority of the fibers have repolarized.
- Myocardial ischemia and electrolyte abnormalities predispose to reentry.
- Can have wavelets or chase its tail.
Cardiac Dysrhythmias (Analysis)
- ECG recordings allow measurement of waveform amplitude, duration, and heart rate..
Cardiac Dysrhythmias (Normal Sinus Rhythm)
- Impulse rate between 60 and 100 beats/min.
- Regular rhythm
- Starts in the SA node and follows the normal pathway.
- P wave precedes every QRS complex.
- PR, QRS, QT intervals are of normal duration.
Cardiac Dysrhythmias (Sinus Tachycardia)
- Abnormally fast heart rate of greater than 100 beats/min.
- Often a compensatory response to increased demand for CO or reduced SV.
- Usually occurs from SNS activation.
- Treatment aimed at correcting underlying cause; sympatholytic agents or calcium channel blocking agents may be indicated.
Cardiac Dysrhythmias (Sinus Bradycardia)
- Heart rate lower than 60 beats/min.
- May be normal in physically trained individuals with large resting SVs.
- Usually from parasympathetic activation.
- If slow HR precipitates low CO, treatment includes sympathomimetic or parasympatholytic drugs.
Cardiac Dysrhythmias (Sinus Arrhythmia)
- Associated with fluctuations in autonomic influences and respiratory dynamics.
- May be particularly pronounced in children.
- Must be differentiated from sick sinus syndrome.
- May need a pacemaker.
- Sinus arrhythmia is normal and needs no treatment.
Cardiac Dysrhythmias (Sinus Arrest)
- Absence of impulse initiation in the heart results in electrical asystole..
- Escape rhythm: a slower pacemaker will generally begin to fire after several seconds of sinus arrest
- Pacemaker may be required.
Cardiac Dysrhythmias (Abnormal Site of Impulse Initiation)
- Initiation of cardiac impulse at a site other than the SA node can occur with: SA node failure (allows a slower pacemaker to take over, escape rhythm), Enhanced excitability, triggered activity, or reentrant circuits causing premature depolarization and overriding the SA node.
Cardiac Dysrhythmias (Escape Rhythms)
- Originate in the AV nodal region or ventricular Purkinje fibers.
- Junctional escape rhythm originates in the AV node (rate of 40 to 60 beats/min with normal QRS).
- Ventricular escape rhythm originates in Purkinje fibers (rate of 15 to 40 beats/min with abnormally wide QRS).
- P wave: abnormal or absent.
Cardiac Dysrhythmias (Atrial Dysrhythmias)
- Premature atrial complexes (PACs): originate in the atria but not the SA node; PACs occur earlier than normal, preceded by a P wave, and have a normal QRS complex configuration.
- Frequent PACs may indicate underlying pathophysiologic process and be precursors to more serious dysrhythmias.
- Paroxysmal focal atrial tachycardia: burst of atrial complexes resembling several PACs in a row.
Cardiac Dysrhythmias (Atrial Flutter and Fibrillation)
- Flutter is typically manifested by a rapid atrial rate of 240 to 350 beats/min with sawtooth pattern.
- Type I-240 to 350 beats/min, Type II-over 350 beats/min.
- Fibrillation is a completely disorganized and irregular atrial rhythm accompanied by an irregular ventricular rhythm.
- Can cause thrombi.
Cardiac Dysrhythmias (Junctional Dysrhythmias)
- May be initiated by two junctional zones: Area just proximal to the AV node, Area just distal to the AV node.
- Junctional tachycardia is a rapid junctional discharge (70 to 140 beats/min).
- Resembles a series of junctional premature beats with P waves preceding, following, or buried in the QRS complexes.
- Supraventricular tachycardia: may refer to junctional or atrial tachycardia.
Cardiac Dysrhythmias (Ventricular Dysrhythmias)
- Premature ventricular complexes (PVCs): arise from the ventricular myocardium; do not activate the atria or depolarize the sinus node.
- Bizarre QRS, Compensatory pause is common.
- Bigeminy (every other beat) or trigeminy (every third beat).
- With high frequency, CO may be compromised.
Cardiac Dysrhythmias (Ventricular Tachycardia)
- Three or more consecutive ventricular complexes at a rate greater than 100 beats/minute.
- ECG depicts a series of large, wide, undulating waves.
- P waves are not associated with the QRS complexes.
- May be fatal if not rapidly managed.
Cardiac Dysrhythmias (Ventricular Fibrillation)
- Rapid, uncoordinated cardiac rhythm resulting in ventricular quivering and lack of effective contraction.
- ECG is rapid and erratic, with no identifiable QRS complexes.
- Results in death if not reversed within minutes.
- Defibrillation, CPR, Antiarrhythmia drugs.
Cardiac Dysrhythmias (Conduction Pathway Disturbances)
- Include delays, blocks, and abnormal pathways.
- Conduction blocks and delays: associated with cardiac ischemia and infarction.
- Abnormal pathways: usually congenital.
Cardiac Dysrhythmias (Atrioventricular Conduction Disturbances)
- Atrioventricular block: problem between the sinus impulse and ventricular response.
- Slowed or completely blocked; defect in the AV node, bundle of His, or bundle branches.
- Three types: First-degree block (usually no treatment required), Second-degree block (types I and II), Third-degree block (complete).
Cardiac Dysrhythmias (Types of Second-Degree Block)
- Type I (Wenckebach, Mobitz type 1): characterized by progressive prolongation of the PR interval until one P wave is not conducted; associated with AV nodal ischemia.
- Type II second-degree block: identified by a rhythm showing consistent PR interval with some non-conducted P waves; more serious because has a tendency to progress to complete AV (third-degree) block.
Cardiac Dysrhythmias (Third-Degree Block)
- Diagnosed when there is no apparent association between atrial and ventricular conduction; is serious, as it can lead to slow ventricular rhythm and poor CO.
Cardiac Dysrhythmias (Abnormal Conduction Pathways)
- Accessory pathways: congenital abnormalities of the cardiac conduction system; have extra conduction paths.
- Alternative pathways for depolarization result in abnormally early ventricular depolarization following atrial depolarizations.
- Wolff-Parkinson-White syndrome
Cardiac Dysrhythmias (Intraventricular Conduction Defects)
- Bundle branch block: abnormal conduction of impulses through the intraventricular bundle branches.
- Right bundle branch supplies right ventricle.
- Left bundle branch supplies left ventricle (further divided into anterior, posterior, and septal).
Cardiac Dysrhythmias (Treatment)
- Indicated when dysrhythmias produce significant symptoms or are expected to progress to a more serious level.
- Antiarrhythmic drugs used (may be proarrhythmic).
- Measures to improve CO (pacemakers and drugs to increase contractility).
- Ablation procedures.
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Description
Test your knowledge on cardiac dysrhythmias and their mechanisms. This quiz covers topics such as depolarizing mechanisms, reentry phenomena, and the role of ECG in analyzing dysrhythmias. Assess your understanding of how these issues impact heart function.
