Cardiology Practice Questions

Q: What is the most common cardiac arrhythmia?

Atrial fibrillation. **Explanation:** **Atrial Fibrillation (AF)** is the correct answer as it is globally recognized as the most common sustained cardiac arrhythmia in clinical practice [1]. Its prevalence increases significantly with age, affecting approximately 10% of individuals over the age of 80 [1]. The underlying pathophysiology involves multiple re-entrant wavelets or focal triggers (most commonly originating from the **pulmonary veins**) that lead to disorganized atrial electrical activity and an "irregularly irregular" ventricular response [1]. **Analysis of Incorrect Options:** * **Inappropriate Sinus Tachycardia (IST):** This is a relatively rare condition characterized by an elevated resting heart rate or disproportionate response to exertion without an underlying cause. It is far less common than AF. * **Premature Junctional Complexes (PJCs):** While these are common ectopics, they are usually transient and do not constitute a sustained rhythm disorder like AF [2]. * **Atrial Flutter:** Although it shares similar risk factors with AF, it is significantly less common. It is characterized by a "saw-tooth" pattern on ECG and is caused by a large re-entrant circuit, typically around the tricuspid annulus (macro-reentry) [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Hypertension and Valvular Heart Disease (Mitral Stenosis). * **ECG Hallmark:** Absence of P-waves and "irregularly irregular" R-R intervals. * **Management:** The primary goals are rate control (Beta-blockers/CCBs), rhythm control (Amiodarone/Flecainide), and **anticoagulation** (based on CHADS₂-VASc score) to prevent embolic stroke [1]. * **Ashman Phenomenon:** A long R-R interval followed by a short R-R interval resulting in an aberrantly conducted QRS complex, often seen in AF.

Q: Which of the following cardiac rhythms is NOT associated with hyperkalemia?

Torsades de pointes. Explanation: **Hyperkalemia** affects cardiac conduction by partially depolarizing the resting membrane potential, which decreases the excitability of the myocardium and slows impulse conduction [1]. **Why Torsades de pointes is the correct answer:** Torsades de pointes (TdP) is a specific form of polymorphic ventricular tachycardia associated with a **prolonged QT interval** [2]. It is characteristically caused by **hypokalemia**, hypomagnesemia, and hypocalcemia—not hyperkalemia [3]. Hyperkalemia typically causes a *shortened* QT interval due to rapid repolarization (manifesting as tall, peaked T waves) [1]. **Analysis of incorrect options:** * **Sinus Bradycardia & Sinus Arrest:** As potassium levels rise, the sinoatrial (SA) node becomes depressed. This leads to bradycardia and, eventually, sinus arrest or "sine wave" rhythms as the P-wave disappears due to atrial paralysis [1]. * **Ventricular Fibrillation:** Severe hyperkalemia (typically >8.0 mEq/L) leads to profound conduction delays and increased myocardial irritability, which can degenerate into ventricular tachycardia or ventricular fibrillation, leading to cardiac arrest [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Sequential ECG changes in Hyperkalemia:** Tall peaked T waves (earliest) → Prolonged PR interval → Loss of P waves (Atrial paralysis) → Widening of QRS complex → Sine wave pattern → Asystole/V-Fib [1]. * **Treatment Priority:** Intravenous **Calcium Gluconate** is the first-line treatment to stabilize the cardiac membrane (it does not lower K+ levels). * **Rule of Thumb:** "Hypo" (K, Mg, Ca) prolongs the QT; "Hyper" (K, Ca) shortens the QT.

Q: Comment on the diagnosis?

Myocardial infarction. ***Myocardial infarction*** - **ST elevation** in multiple leads with **pathological Q waves** are classic ECG findings indicating **acute myocardial infarction** with full-thickness myocardial damage. - **Reciprocal changes** in opposite leads further support the diagnosis of **STEMI** with localized coronary artery occlusion. *Prinzmetal angina* - Characterized by **transient ST elevation** during vasospastic episodes that **resolves completely** between attacks. - **No pathological Q waves** develop as there is no permanent myocardial damage or necrosis. *Pulmonary embolism* - ECG typically shows **S1Q3T3 pattern** with **right heart strain** features like right axis deviation. - May show **T wave inversions in V1-V4** and **incomplete RBBB**, not the ST elevation pattern seen here. *Hyperkalemia* - ECG shows **peaked T waves**, **widened QRS complexes**, and **flattened P waves** in severe cases. - Advanced hyperkalemia may progress to a **sine wave pattern**, completely different from the acute coronary syndrome changes.

Q: J waves are typically seen in which of the following conditions?

Hypothermia. Explanation: J waves, also known as Osborn waves, are positive deflections occurring at the junction between the QRS complex and the ST segment (the J-point). 1. Why Hypothermia is Correct: Hypothermia is the classic cause of J waves. They typically appear when the core body temperature drops below 32°C (90°F). The physiological basis involves a temperature-sensitive gradient between the epicardium and endocardium during early ventricular repolarization, leading to a prominent notch at the J-point. The size of the J wave often correlates with the severity of the hypothermia. 2. Why Incorrect Options are Wrong: * Hyperthermia: Does not cause J waves; it is more commonly associated with sinus tachycardia or nonspecific ST-T changes [1]. * Hypokalemia: Characterized by U waves, flattened T waves, and ST-segment depression. * Hyperkalemia: Classically presents with tall, peaked "tented" T waves, widened QRS complexes, and loss of P waves [1]. 3. NEET-PG High-Yield Pearls: * Other causes of J waves: Hypercalcemia, Brugada syndrome, and early repolarization syndrome (normal variant). * ECG Triad of Hypothermia: 1. Sinus bradycardia (most common arrhythmia). 2. J waves (Osborn waves). 3. Prolonged PR, QRS, and QT intervals. * Artifact Alert: Shivering in hypothermic patients can cause a baseline artifact on ECG that mimics atrial flutter. * Management: Treatment focuses on active/passive rewarming rather than anti-arrhythmics, as J waves resolve with normalization of temperature.

Q: What is considered a wide QRS duration?

Greater than 0.12 seconds. ### Explanation The QRS complex represents **ventricular depolarization**. In a healthy heart, electrical impulses travel rapidly through the specialized His-Purkinje system, ensuring synchronous ventricular contraction. **1. Why 0.12 seconds is correct:** A normal QRS duration is typically between **0.06 and 0.10 seconds** (1.5 to 2.5 small squares). A duration of **≥ 0.12 seconds** (3 small squares) is the standard diagnostic threshold for a **"Wide QRS."** This delay indicates that ventricular depolarization is occurring slowly, usually because the impulse is traveling through the working myocardium rather than the rapid conduction system [1]. **2. Why the other options are incorrect:** * **Options A and B (0.8 and 0.9 seconds):** These values are physiologically impossible for a single QRS complex. A duration of 0.8 seconds would mean a single heartbeat takes nearly a full second just to depolarize the ventricles, which is incompatible with life. These options likely confuse *seconds* with *milliseconds* (e.g., 80ms or 90ms), which fall within the normal range. * **Option D:** Since A and B are incorrect, "All the above" is invalid. **Clinical Pearls for NEET-PG:** * **Differential Diagnosis of Wide QRS:** 1. **Bundle Branch Blocks (RBBB/LBBB):** The most common cause. 2. **Ventricular Ectopy:** Premature Ventricular Contractions (PVCs) or Ventricular Tachycardia (VT) [2]. 3. **Pre-excitation:** Wolff-Parkinson-White (WPW) syndrome (due to the Delta wave) [1]. 4. **Metabolic/Toxic:** Hyperkalemia (classic "sine wave" appearance) or Sodium Channel Blocker toxicity (e.g., TCA overdose) [3]. 5. **Pacemaker-induced** rhythms. * **High-Yield Tip:** In the setting of tachycardia, a wide QRS should be considered **Ventricular Tachycardia** until proven otherwise [2].

Q: What is the most common infection in patients with prosthetic valves?

Staphylococcus. The most common cause of Prosthetic Valve Endocarditis (PVE) is **Staphylococcus**. The etiology is further divided based on the timing of the infection post-surgery: 1. **Early PVE ( 1 year post-surgery):** The microbiology begins to resemble native valve endocarditis, where **Staphylococcus aureus** and Viridans group Streptococci are the most frequent isolates [2]. Since both early and late phases are dominated by different species of the same genus, **Staphylococcus** is the overall correct answer. **Analysis of Incorrect Options:** * **Pneumococcus (Streptococcus pneumoniae):** While a cause of native valve endocarditis (historically part of Osler’s triad), it is an uncommon cause of prosthetic valve infections [2]. * **Pseudomonas:** This is a Gram-negative organism occasionally seen in intravenous drug users (IVDU) or healthcare-associated infections, but it is not the most common overall. * **Enterococci:** These are the third most common cause of PVE (after Staphylococci and Streptococci), often associated with urinary tract manipulations or gastrointestinal procedures [2]. **Clinical Pearls for NEET-PG:** * **Most common overall cause of Endocarditis (Native Valve):** *Staphylococcus aureus* (previously Viridans Streptococci) [2]. * **Most common cause in IV drug users:** *Staphylococcus aureus* (often involving the Tricuspid valve) [2]. * **Culture-negative Endocarditis:** Most commonly due to prior antibiotic use or fastidious organisms like the **HACEK** group or *Coxiella burnetii*. * **Streptococcus bovis (S. gallolyticus):** If found in endocarditis, always screen the patient for **Colorectal Carcinoma** [2].

Question 1

What is the most common cardiac arrhythmia?

Accepted Answer

Atrial fibrillation

Answer

Inappropriate sinus tachycardia

Answer

Premature junctional complexes

Answer

Atrial flutter

Question 2

Which of the following cardiac rhythms is NOT associated with hyperkalemia?

Accepted Answer

Torsades de pointes

Answer

Sinus arrest

Answer

Sinus bradycardia

Answer

Ventricular fibrillation

Question 3

Which of the following conditions are typically associated with a continuous murmur?

Accepted Answer

Patent ductus arteriosus with reversal of shunt

Answer

Aortic stenosis combined with aortic regurgitation

Answer

Systemic arteriovenous fistula

Answer

Aortopulmonary window

Question 4

Comment on the diagnosis?

Accepted Answer

Myocardial infarction

Answer

Prinzmetal angina

Answer

Pulmonary embolism

Answer

Hyperkalemia

Question 5

J waves are typically seen in which of the following conditions?

Accepted Answer

Hypothermia

Answer

Hyperthermia

Answer

Hypokalemia

Answer

Hyperkalemia

Question 6

Regarding Wolf-Parkinson-White (WPW) syndrome, which of the following statements is incorrect?

Accepted Answer

Type a is seen in association with Ebstein's anomaly.

Answer

There is a risk of ventricular tachycardia.

Answer

Presentation may be with hydrops fetalis.

Answer

Flecainide reduces the recurrence risk of tachycardias.

Question 7

What is considered a wide QRS duration?

Accepted Answer

Greater than 0.12 seconds

Answer

Greater than 0.8 seconds

Answer

Greater than 0.9 seconds

Answer

All the above

Question 8

A 68-year-old man presents with progressive shortness of breath. He had a metallic heart valve replacement 13 years ago for severe aortic stenosis. Which of the following clinical findings is most indicative of a failing aortic valve replacement?

Accepted Answer

Early diastolic murmur heard at the left sternal edge

Answer

Clicking sound to S2

Answer

New onset atrial fibrillation

Answer

Ejection systolic murmur heard in the aortic region

Question 9

What is the most common infection in patients with prosthetic valves?

Accepted Answer

Staphylococcus

Answer

Pneumococcus

Answer

Pseudomonas

Answer

Enterococci

Question 10

Which of the following is associated with atherosclerosis?

Accepted Answer

Chlamydia pneumoniae

Answer

Chlamydia trachomatis

Answer

Chlamydia psittaci

Answer

Chlamydia gingivalis

Cardiology — MCQs

Cardiology — MCQs

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