Cardiology Concepts and ECG Interpretations

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Questions and Answers

What is the definitive treatment for AVNRT?

Vagal maneuvers

Catheter ablation targeting the slow pathway (correct)

Catheter ablation of the accessory pathway

Administration of beta-blockers

Which feature is indicative of Slow-Fast AVNRT on an ECG?

Narrow QRS complex with retrograde P waves (correct)

Regularly spaced R-R intervals

Presence of T-wave inversions

Wide QRS complex

Which of the following is the first-line therapy for the acute termination of AVNRT?

Adenosine

Vagal maneuvers (correct)

Calcium channel blockers

Catheter ablation

What condition can increase the risk of gastroesophageal reflux disease (GERD)?

Weak lower esophageal sphincter Signup and view all the answers

What effect does hypocalcemia have on the myocardial contractions?

Decreases myocardial contractions due to decreased calcium-induced calcium release. Signup and view all the answers

What triggers transient relaxation of the lower esophageal sphincter in GERD?

Alcohol consumption Signup and view all the answers

Which of the following ECG manifestations is associated with hypocalcemia?

Prolonged QT interval. Signup and view all the answers

How does hypernatremia primarily influence depolarization?

It slightly speeds up depolarization and may shorten action potential duration. Signup and view all the answers

Which of the following is NOT a complication associated with untreated GERD?

Increased gastric acid production Signup and view all the answers

Which ECG feature may be observed in severe cases of hyponatremia?

Prolonged PR interval. Signup and view all the answers

Which of these factors can contribute to the development of GERD?

Transient lower esophageal sphincter relaxation Signup and view all the answers

What is the expected effect of hypermagnesemia on cardiac conduction?

Slows down conduction but does not affect ECG. Signup and view all the answers

What role does delayed gastric emptying play in GERD?

It prolongs the potential for reflux to occur. Signup and view all the answers

What is a potential ECG manifestation of hypomagnesemia?

Early afterdepolarization. Signup and view all the answers

Which of the following best describes the effect of hyponatremia on overall cell excitability?

Decreases overall cell excitability. Signup and view all the answers

How does hypernatremia affect the QRS complex?

It may cause a mild increase in QRS amplitude. Signup and view all the answers

What are the components of Charcot's Triad?

Fever, Jaundice, RUQ Pain Signup and view all the answers

Which treatment is considered emergent for jaundice caused by biliary obstruction?

Emergent ERCP Signup and view all the answers

What does MRCP stand for and what is its primary use?

Magnetic Resonance Cholangiography, for bile duct visualization Signup and view all the answers

In the liver lobule structure, what is the role of the sinusoids?

Receive mixed blood from the hepatic arteriole and portal venule Signup and view all the answers

Which of the following best describes the function of hepatocytes?

Store nutrients and produce bile Signup and view all the answers

Which of the following statements about the portal triad is true?

It consists of a hepatic arteriole, a bile ductule, and a portal venule. Signup and view all the answers

What additional symptoms are included in Reynold's Pentad?

Hypotension and altered mental status Signup and view all the answers

What is the anatomical path of blood from the abdominal aorta to the hepatic vein?

Abdominal aorta → Celiac trunk → Common hepatic artery → Portal vein → Central vein Signup and view all the answers

What ECG manifestation is commonly associated with hypokalemia?

Prolonged QT interval Signup and view all the answers

Which type of cells has a longer refractory period due to the presence of a plateau phase?

Cardiac myocytes Signup and view all the answers

What mechanism is primarily activated due to decreased renal perfusion during lactate accumulation?

Renin-Angiotensin-Aldosterone System Signup and view all the answers

What does the absolute refractory period (ARP) indicate?

Cell is completely unexcitable Signup and view all the answers

Which symptom is NOT commonly associated with lactate accumulation and metabolic acidosis?

Elevated blood pressure Signup and view all the answers

During which phases are fast Na⁺ channels inactivated leading to the ARP?

Phase 0, 1, and 2 Signup and view all the answers

How does catecholamine release affect myocardial oxygen demand?

Increases heart rate and afterload Signup and view all the answers

What physiological role does the long refractory period serve in the ventricles?

It prevents tetanic contractions Signup and view all the answers

What characterizes the effective refractory period (ERP)?

Cell can depolarize but not propagate Signup and view all the answers

What is the primary consequence of elevated left ventricular end-diastolic pressure (LVEDP)?

Backflow of blood into pulmonary circulation Signup and view all the answers

Which treatment option is typically used to support mechanical circulation?

Intra-aortic balloon pump (IABP) Signup and view all the answers

What is the primary determinant of the refractory period in nodal cells?

Recovery of L-type Ca²⁺ channels Signup and view all the answers

What happens to the voltage-gated Na⁺ channels during phases of an action potential?

They cycle through resting, activated, and inactivated states Signup and view all the answers

What effect does high blood osmolarity have on antidiuretic hormone (ADH) release?

Enhances ADH release Signup and view all the answers

Which hemodynamic parameter is expected to be LOW in the context of lactate accumulation?

Cardiac Output (CO) Signup and view all the answers

What is a potential sequela of high myocardial oxygen demand coupled with low oxygen delivery?

Worsened myocardial injury Signup and view all the answers

What is the primary function of Kupffer cells in the liver?

Immune surveillance and breakdown of old red blood cells Signup and view all the answers

Which zone of the liver lobule is most resistant to ischemia?

Zone 1 (Periportal Zone) Signup and view all the answers

What is the role of stellate cells in the liver?

Storage of fat and fat-soluble vitamins Signup and view all the answers

What metabolic activities are primarily associated with Zone 3 (Centrilobular Zone)?

Detoxification and lipogenesis Signup and view all the answers

Which liver condition is characterized by chronic damage leading to fibrosis?

Cirrhosis Signup and view all the answers

Which statement regarding the Space of Disse is correct?

It serves as an exchange space between sinusoids and hepatocytes. Signup and view all the answers

Which zone of the liver lobule is the least oxygenated and most vulnerable to damage?

Zone 3 (Centrilobular Zone) Signup and view all the answers

What is a hallmark of lobular injury in hepatic diseases?

Loss of lobular structure Signup and view all the answers

What condition is characterized by the obstruction of bile flow due to gallstones in the common bile duct?

Choledocholithiasis Signup and view all the answers

Which symptom is typically associated with cholangitis due to biliary obstruction?

Severe jaundice Signup and view all the answers

What is the primary purpose of performing an MRCP in the diagnosis of gallstone disease?

To confirm the presence of CBD stones non-invasively Signup and view all the answers

Which laboratory finding is most indicative of cholestasis due to biliary obstruction?

Markedly elevated ALP/GGT levels Signup and view all the answers

What complication can occur if choledocholithiasis is left untreated?

Cholangitis or pancreatitis Signup and view all the answers

What effect does hyperkalemia have on the duration of the action potential?

It shortens the action potential duration. Signup and view all the answers

What is an ECG manifestation associated with hypokalemia?

U wave. Signup and view all the answers

How does hypercalcemia primarily affect the refractory period of cardiac myocytes?

It decreases the refractory period. Signup and view all the answers

What clinical risk is associated with prolonged QT interval as a result of hypokalemia?

Torsade de pointes. Signup and view all the answers

What happens to the resting membrane potential (RMP) during hyperkalemia?

It becomes more positive. Signup and view all the answers

What is a significant effect of hypocalcemia on the myocardial contraction process?

Decreased strength of contraction. Signup and view all the answers

How does the T wave manifest on an ECG during hyperkalemia?

It shows a sine-wave pattern. Signup and view all the answers

What effect does calcium-induced calcium release have on myocardial contractility during hypercalcemia?

Increases myocardial contractility. Signup and view all the answers

What is a consequence of H. pylori infection on the stomach lining?

Increased damage to acid-producing cells Signup and view all the answers

What is the primary effect of chronic NSAID use on the stomach?

Reduced prostaglandin production Signup and view all the answers

How does smoking affect the gastric mucosa?

Increases acid production Signup and view all the answers

What leads to duodenal ulcer formation in the context of H. pylori infection?

Increased acid flow into the duodenum Signup and view all the answers

What effect does damage to the acid-producing cells have in the stomach?

Reduced acid production Signup and view all the answers

What role does urease play in H. pylori infection?

Increases inflammation Signup and view all the answers

Which of the following leads to hypochlorhydria in diffuse gastritis?

Damage to the parietal cells Signup and view all the answers

What is a common effect of NSAIDs on the gastric mucosal lining?

Decreased blood flow to the gastric mucosa Signup and view all the answers

Which phase of the myocyte action potential is characterized by rapid depolarization due to sodium influx?

Phase 0 (Rapid Depolarization) Signup and view all the answers

During which phase does the calcium-induced calcium release (CIRC) occur?

Phase 2 (Plateau Phase) Signup and view all the answers

What is the primary ion flow during Phase 3 of the myocyte action potential?

Increased K⁺ efflux Signup and view all the answers

What is maintained by the Na⁺/K⁺-ATPase during the resting membrane potential?

A negative charge inside the cell Signup and view all the answers

Which phase corresponds with the T wave on the ECG?

Phase 3 (Rapid Repolarization) Signup and view all the answers

What initiates depolarization in cardiac myocytes?

Na⁺ and Ca²⁺ entering the cell Signup and view all the answers

Which phase is responsible for maintaining a stable myocardium contraction duration?

Phase 2 (Plateau Phase) Signup and view all the answers

At what membrane potential do voltage-gated Na⁺ channels begin to open?

-70 mV Signup and view all the answers

What is the primary function of Phase II reactions in drug metabolism?

To convert lipid-soluble toxins into water-soluble forms Signup and view all the answers

Which of the following enzymes is involved in alcohol metabolism?

Acetaldehyde dehydrogenase Signup and view all the answers

What is the role of Kupffer cells in the liver?

To filter pathogens and debris from the blood Signup and view all the answers

What primarily determines coagulation times, specifically the Prothrombin Time (PT)?

The presence of Factor VII Signup and view all the answers

How does the liver contribute to glucose homeostasis?

By regulating insulin and glucagon interactions Signup and view all the answers

Which process is NOT performed by the liver in the context of detoxification?

Synthesizing steroid hormones Signup and view all the answers

Which type of compounds does the liver primarily convert through Phase I reactions?

Lipid-soluble metabolites to active forms Signup and view all the answers

What are the major polar groups that drugs are conjugated with during Phase II reactions?

Various polar groups via transferase enzymes Signup and view all the answers

What condition is indicated by severe hepatocellular damage and may lead to mixed hyperbilirubinemia?

Hepatitis Signup and view all the answers

Which symptom is NOT commonly associated with cholelithiasis?

Persistent RUQ pain lasting more than 6 hours Signup and view all the answers

What is a key differentiating factor between cholecystitis and cholelithiasis?

Cholecystitis involves inflammation and infection. Signup and view all the answers

Which are risk factors for developing cholelithiasis?

Females over 40 years old Signup and view all the answers

Which of the following statements about Dubin-Johnson Syndrome is true?

It is characterized by defective hepatic transport, leading to conjugated hyperbilirubinemia. Signup and view all the answers

What is a common complication associated with untreated cholecystitis?

Gallbladder perforation Signup and view all the answers

Which symptom is often used to diagnose cholecystitis?

Murphy's Sign Signup and view all the answers

In what condition does bile stasis occur due to gallstone obstruction?

Cholecystitis Signup and view all the answers

Study Notes

Acute MI (Different Coronary Arteries)

Acute MI usually begins with coronary artery disease (CAD), characterized by atherosclerotic plaque formation in coronary arteries.
Plaque consists of cholesterol, inflammatory cells, and connective tissue within arterial walls.
Plaque rupture or erosion triggers a cascade of events:
- Activation of platelets
- Release of Tissue Factor (Factor III)
- Conversion of Factor X to Xa
- Conversion of Factor II to IIa
- Conversion of Factor I to Ia
- Formation of a thrombus (partial or complete obstruction).
Thrombus leads to myocardial ischemia.
Reduced or absent blood flow deprives myocardial tissue of oxygen and nutrients.
Ischemia affects the subendocardial layer, furthest from the blood supply and with the highest oxygen demand, most susceptible to irreversible injury.
Myocyte necrosis releases intracellular contents (troponin, CK-MB) into the bloodstream.
Inflammatory response & leukocytes infiltrate the affected areas to remove dead cells and prolong injury.

Stable Angina, Angina Pectoris, Unstable Angina, NSTEMI, STEMI

Stable angina: Predictable chest pain related to exertion or stress.
Angina Pectoris: General term for angina, which is chest pain caused by reduced blood flow to the heart muscle.
Unstable angina: Chest pain that is new, more severe, and occurs at rest or with less exertion than previously tolerated.
NSTEMI (Non-ST-elevation myocardial infarction): Coronary artery blockage, but the blockage is not complete.
STEMI (ST-elevation myocardial infarction): Complete coronary artery blockage, leading to irreversible myocardial damage & necrosis.

Cardiac Shock

Pump failure caused by:
- MI (most common)
- HF
- Myocarditis
- Valve dysfunction
Reduced cardiac output → hypotension.
Impaired coronary artery perfusion → worsening ischemia.
Reduced organ perfusion → tissue hypoperfusion leads to ischemia and anaerobic metabolism
Metabolic acidosis: lactate buildup.
Kidney injury, altered mental status (brain), and impaired liver metabolism (jaundice)
Systemic Hypoperfusion triggers circulatory failure and possible sepsis.

Cardiogenic Shock Compensation Mechanisms

Sympathetic nervous system activation
- Increased heart rate
- Vasoconstriction
- Increased blood pressure
Renin-angiotensin-aldosterone system (RAAS) activation
- Maintaining blood pressure by retaining sodium & water.

Pulmonary Edema (Associated with Hypertensive Crisis)

Elevated LVEDP (Left Ventricular End Diastolic Pressure)
Increased capillary hydrostatic pressure
Reduced oncotic pressure
Impaired lymphatic drainage

Starling Forces

Movement of fluid between capillaries and surrounding tissues.
Relationship between capillary hydrostatic pressure (Pc), interstitial hydrostatic pressure (Pi), capillary oncotic pressure (πc), and interstitial oncotic pressure (πi)
Net filtration pressure (NFP) = (Pc - Pi) - (πc - πi).
Increased pressure → more fluid, leading to edema.

Cardiogenic Shock Treatment

Restore hemodynamic stability (fluids, vasopressors)
Treat underlying cause
Support (monitoring vital functions & managing complications).

Cardiac Tamponade

Obstructive shock caused by fluid accumulation in the pericardial sac
Pericardial effusion compresses the heart → reduced cardiac output (reduced CO).
Symptoms include dyspnea, hypotension, and muffled heart sounds.
Echocardiogram → pericardial effusion, diastolic collapse of the right heart chambers

Cardiac Tamponade Treatment

Pericardiocentesis → remove the accumulated fluid form the pericardial sac
Consider inotropes and in cases of worsening, mechanical support (if needed)

Relationship between CO, SVR, and BP

MAP = CO x SVR (mean arterial pressure = cardiac output x systemic vascular resistance)
Increased CO: raises BP if SVR remains constant.
Decreased CO: lowers BP if SVR doesn't compensate.

Frank-Starling Law

Relationship between preload, contractility and stroke volume • Increasing preload (stretching of cardiac fibres) → proportionally increases stroke volume up to an optimum point.
At high preload, overstretched fibers do not respond effectively → reduced contractility → reduced stroke volume.

Left Ventricular Hypertrophy (LVH), Concentric vs. Eccentric (FORMATIVE)

Concentric: Increased wall thickness with a relatively smaller chamber size triggered by pressure overload. (e.g. hypertension or aortic stenosis)
Eccentric: Increased wall size and chamber enlargement with normal or even decreased wall thickness triggered by volume overload as a compensation. (e.g., valvular regurgitation and high-output states).
Both lead to impaired relaxation and filling
Clinical presentation depends on the predominant mechanism

Aortic Stenosis

Narrowing of the aortic valve → increased afterload.
Reduced stroke volume and cardiac output
Blood pressure increases due to increased afterload and reduced stroke volume
EKG findings consistent with these effects

Mitral Stenosis

Narrowing of the mitral valve → reduced preload.
Reduced stroke volume and ventricular filling → reduced cardiac output

Cardiac Action Potential

Phase 0: Rapid depolarization mediated largely by fast sodium channels (voltage-gated sodium channels) resulting in rising action potentials
Phase 1: Early repolarization, rapid potassium efflux through these voltage-gated channels resulting in early phase of repolarization
Phase 2 Plateau phase, the slow calcium influx balances potassium efflux, contributing to prolonged contraction required for effective ejection of blood from the heart
Phase 3: Rapid repolarization, voltage gated potassium channels open further, triggering the efflux of potassium ions
Phase 4: Resting membrane potential, maintained by sodium-potassium ATPase, responsible for returning the cells to a resting potential after each contraction

Nodal Action Potential

Phase 4: the slow spontaneous depolarization period, characterized by a slow influx of sodium and calcium ions, which gradually raise the membrane potential towards the threshold potential
Phase 0: depolarization from the influx of fast sodium and calcium ions, eventually initiating the firing of an action potential
Phase 1: very brief and small repolarization, triggered by the closure of sodium channels and the opening of the potassium channels, which causes slight drop in membrane potential
Phase 2: plateau phase, occurs because calcium influx (through L-type calcium channels) balances potassium efflux
Phase 3: rapid repolarization, which is due to the closing of the calcium channels and a major efflux of potassium.
Phase 4: resting membrane potential, occurs rapidly from the movement of potassium to the outside of the cell.

Refractory Period (Nodal)

ARP (absolute refractory period): period before the cell can be excited by a stimulus
ERP (effective refractory period): period where the cell may respond to a stimulus by depolarizing minimally and not for propagation of the action potential
RRP (relative refractory period): period following the ARP where the cells respond to stronger than normal stimuli by initiating an action potential.

Prolonged QT Interval (ECG Manifestations)

Hypercalcemia: Short QT interval, faster repolarization.
Hypocalcemia: Prolonged QT interval, slower repolarization.
Hypokalemia: Flattened T waves, prolonged QT interval, slower repolarization.
Hyperkalemia: Peaked T waves, shortened QT interval, rapid repolarization.

Prolonged PT (prothrombin time) and INR (international normalized ratio)
Decreased production of clotting factors
Liver dysfunction → impaired synthesis of coagulation factors → prolonged clot formation (hemorrhage potential)
Vitamin K deficiency could occur in patients with cholestasis (obstruction of the bile ducts) → impairment in Vitamin K absorption.
DIC (disseminated intravascular coagulation) - a serious and sometimes life-threatening condition

Liver Function Tests Elevated ALT, AST, ALP (and GGT) & Bilirubin

ALT (alanine aminotransferase, a measure of hepatocellular injury)
AST (aspartate aminotransferase, a measure of hepatocellular injury)
ALP (alkaline phosphatase, indicates cholestatic processes, as commonly found in the bile ducts.)
GGT (gamma-glutamyl transpeptidase) → enzyme found in the bile ducts so high values suggest cholestasis
Bilirubin (elevated levels suggest the liver is not excreting it efficiently → jaundice potential)

Portal Hypertension

Increased resistance to blood flow in the liver → elevated pressure in the portal vein. Common causes are cirrhosis, portal vein thrombosis.
Complications include ascites, varices (enlarged veins), and hepatic encephalopathy

Varices

Dilated, and weakened veins. Common sites are esophagus and stomach.
Due to portal hypertension Risk of bleeding → hematemesis, melena.
Endoscopy (gold standard for detection and grading)
Medical management: non-selective Beta blockers; endoscopic variceal ligation (EVL)

Medications that interfere with Liver Function

Many medications, including NSAIDs (nonsteroidal anti-inflammatory drugs), other medications → can strain the liver if administered too often or in high doses.

Hyperbilirubinemia

Jaundice: yellowing of skin, sclera & mucous membranes due to elevated bilirubin levels
Pre-hepatic: RBC lysis → unconjugated bilirubin
Hepatic: Impaired bilirubin conjugation → Mixed (unconjugated & conjugated) bilirubin
Post-hepatic: Obstruction of bile ducts → conjugated bilirubin

Cholangitis/Cholecystitis

Cholangitis: Inflammation of the common bile duct. Often caused by gallstones obstructing the duct, infection in the bile ducts.
Cholecystitis: Inflammation of the gallbladder, likely from gallstones obstructing the cystic duct.

Nerve Conduction (general)

Action potentials travel along the sarcolemma and into the T-tubules via myofibrils leading to the release of Ca++ initiating contraction
Depolarization → opening of voltage-gated channels → Na+ inflow → K+ outflow

Cholinergic Crisis/ Myasthenia Crisis

Cholinergic crisis due to excessive acetylcholine at the neuromuscular junction, leading to muscle weakness, fasciculations, and excessive sweating.
Myasthenia Crisis → muscle weakness due to insufficient acetylcholine at the neuromuscular junction → caused by medications/ disease processes impacting acetylcholine receptors at the NMJ.

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Description

Test your knowledge on the treatment of AVNRT and its associated ECG features. This quiz covers conditions like GERD, hypocalcemia, and various electrolyte imbalances affecting cardiac function. Challenge yourself with scenarios and questions based on clinical practices.