Cardiology — MCQs

Cardiology Indian Medical PG Practice Questions and MCQs

Question 971: A routine check-up for a middle-aged man shows left axis deviation in the ECG. Left axis deviation is seen in all of the following conditions, EXCEPT:

A. Dextrocardia (Correct Answer)
B. Wolff-Parkinson-White syndrome
C. Septum primum defect
D. COPD

Explanation: **Explanation:** The mean electrical axis of the heart normally ranges from **-30° to +90°** [1]. Left Axis Deviation (LAD) is defined as an axis more negative than -30°. **Why Dextrocardia is the correct answer:** In **Dextrocardia**, the heart is situated in the right hemithorax with its apex pointing to the right. This anatomical reversal causes a **Right Axis Deviation (RAD)** on a standard ECG, along with global lead reversal (negative P waves and QRS complexes in Lead I). Therefore, it does not cause LAD. **Analysis of other options:** * **Wolff-Parkinson-White (WPW) Syndrome:** Depending on the location of the accessory pathway (Bundle of Kent), WPW can mimic various axis deviations. A right-sided accessory pathway causes early activation of the right ventricle, shifting the vector to the left, resulting in **LAD**. * **Septum Primum Defect (ASD):** This is a high-yield classic. Unlike Secundum defects (which cause RAD), Primum defects are associated with an abnormal conduction system and left anterior fascicular block, leading to a characteristic **LAD**. * **COPD:** While COPD typically causes RAD (due to Cor Pulmonale), it can occasionally present with a "pseudo-left axis" or extreme axis deviation due to hyperinflated lungs and the vertical position of the heart. However, in the context of standard NEET-PG patterns, Dextrocardia is the most definitive cause of RAD, making it the "except" choice. **NEET-PG High-Yield Pearls:** * **Causes of LAD:** Left Anterior Fascicular Block (LAFB), Inferior Wall MI, Left Ventricular Hypertrophy (LVH), and Tricuspid Atresia. * **Causes of RAD:** Right Ventricular Hypertrophy (RVH), Left Posterior Fascicular Block (LPFB), Lateral Wall MI, and Pulmonary Embolism. * **Mnemonic for ASD Axis:** **P**rimum = **P**rior (Left) axis; **S**ecundum = **S**ubsequent (Right) axis.

Question 972: Aortic regurgitation does NOT occur in which of the following conditions?

A. Acute Myocardial Infarction (Correct Answer)
B. Marfan's syndrome
C. Rheumatic heart disease
D. Infective endocarditis

Explanation: **Explanation:** **1. Why Acute Myocardial Infarction (AMI) is the Correct Answer:** Acute Myocardial Infarction is a common cause of **Mitral Regurgitation (MR)**, not Aortic Regurgitation (AR). In the setting of an AMI (specifically inferior wall MI), ischemia or rupture of the **papillary muscles** (usually the posteromedial one) leads to acute mitral valve dysfunction [1]. The aortic valve is a semilunar valve and does not possess chordae tendineae or papillary muscles; therefore, its competence is not directly compromised by myocardial necrosis. **2. Analysis of Incorrect Options:** * **Marfan’s Syndrome:** This is a classic cause of **chronic AR**. It involves cystic medial necrosis of the aorta, leading to aortic root dilation and "annuloaortic ectasia," which prevents the valve leaflets from coapting properly. * **Rheumatic Heart Disease (RHD):** RHD is the most common cause of chronic AR in developing countries. It causes inflammation, thickening, and fibrotic scarring of the valve leaflets, leading to retraction and failure of closure [2]. * **Infective Endocarditis (IE):** This is a leading cause of **acute AR**. Bacterial vegetation can cause leaflet perforation or destruction, leading to sudden, severe valvular incompetence [1]. **Clinical Pearls for NEET-PG:** * **Acute AR Causes:** Infective endocarditis, Aortic dissection (Type A), and Trauma. * **Chronic AR Causes:** RHD, Marfan’s, Syphilitic aortitis, and Ankylosing spondylitis [2]. * **High-Yield Sign:** The hallmark of AR is a **wide pulse pressure** and a **decrescendo early diastolic murmur** heard best at the left sternal border [1]. * **Austin Flint Murmur:** A mid-diastolic rumble heard in severe AR due to the regurgitant jet displacing the mitral leaflet [1].

Question 973: A 53-year-old man with a history of angina presents with severe chest pain. ECG shows ST elevation of 4 mm in leads V1-V4. Thrombolysis was performed but the pain and ECG findings persist 90 minutes after thrombolysis. What is the best management for this patient?

A. Rescue PCI (Correct Answer)
B. Primary PCI
C. Delayed PCI
D. IV Abciximab

Explanation: **Explanation:** The patient is presenting with an **ST-Elevation Myocardial Infarction (STEMI)** involving the anterior wall (V1-V4). Despite thrombolytic therapy, he has persistent chest pain and lack of ST-segment resolution after 90 minutes, indicating **failed fibrinolysis**. **1. Why Rescue PCI is correct:** Rescue Percutaneous Coronary Intervention (PCI) is defined as urgent PCI performed on a patient in whom thrombolytic therapy has failed. Failure of thrombolysis is clinically assessed 60–90 minutes post-procedure by: * Less than 50% reduction in ST-segment elevation in the lead with the highest elevation. * Persistent or worsening chest pain. * Hemodynamic or electrical instability. In this case, the persistence of both pain and ECG findings at 90 minutes necessitates immediate mechanical revascularization to salvage the myocardium [1]. **2. Why other options are incorrect:** * **Primary PCI:** This refers to the initial reperfusion strategy performed *instead* of thrombolysis [1]. Since this patient has already received thrombolytics, the procedure is termed "Rescue PCI." * **Delayed PCI:** This is typically performed 24–48 hours after *successful* thrombolysis (Pharmacoinvasive strategy). It is inappropriate here because the thrombolysis failed. * **IV Abciximab:** While glycoprotein IIb/IIIa inhibitors are used during PCI, they are not a standalone treatment for failed thrombolysis and cannot replace mechanical revascularization. **Clinical Pearls for NEET-PG:** * **Time Window:** The "Golden Hour" for STEMI is the first 60 minutes. * **Door-to-Balloon Time:** Should be <90 minutes (at a PCI-capable center). * **Door-to-Needle Time:** Should be <30 minutes (for thrombolysis). * **Most common cause of death post-MI:** Ventricular arrhythmias (specifically VFib) in the pre-hospital phase; Cardiogenic shock in the hospital phase.

Question 974: What is the most common site of myocardial infarction?

A. Anterior wall of the left ventricle (Correct Answer)
B. Posterior wall of the right ventricle
C. Posterior wall of the left ventricle
D. Inferior wall of the left ventricle

Explanation: ### Explanation **1. Why the Correct Answer is Right:** The **Anterior wall of the left ventricle** is the most common site for myocardial infarction (MI). This is because it is supplied by the **Left Anterior Descending (LAD) artery**, which is the most frequently occluded vessel in the coronary anatomy (often referred to as the "widow-maker"). The left ventricle has the highest muscle mass and metabolic demand, making its anterior wall particularly susceptible to ischemic injury when the LAD is compromised [1]. **2. Why the Other Options are Incorrect:** * **Posterior wall of the right ventricle:** Isolated Right Ventricular (RV) infarctions are rare. RV involvement usually occurs as an extension of an inferior wall MI. The RV has lower oxygen demand and better collateral supply compared to the left ventricle [3]. * **Posterior wall of the left ventricle:** This is typically supplied by the Left Circumflex (LCX) artery or the Right Coronary Artery (RCA) [1]. While significant, LCX occlusions are less frequent than LAD occlusions. * **Inferior wall of the left ventricle:** This is the second most common site of MI, usually resulting from occlusion of the **Right Coronary Artery (RCA)**. While common, it statistically trails behind anterior wall MIs. **3. Clinical Pearls for NEET-PG:** * **Vessel Frequency:** LAD (40-50%) > RCA (30-40%) > LCX (15-20%). * **ECG Localization:** * Anterior wall: Leads V1–V4 [2]. * Inferior wall: Leads II, III, aVF [2]. * Lateral wall: Leads I, aVL, V5, V6. * **Complications:** Anterior MIs are more likely to lead to **heart failure** and cardiogenic shock due to the large area of muscle affected. Inferior MIs are frequently associated with **bradyarrhythmias** (AV blocks) because the RCA supplies the SA and AV nodes.

Question 975: What is the first ECG change observed in hyperkalemia?

A. Tall T wave (Correct Answer)
B. Short PR interval
C. Prolonged QT interval
D. Widening of QRS complex

Explanation: In hyperkalemia, the sequence of ECG changes follows a predictable pattern as serum potassium levels rise. [1] **Why "Tall T wave" is correct:** The earliest manifestation of hyperkalemia (typically at $K^+ > 5.5$ mEq/L) is the appearance of **tall, peaked, "tented" T waves**, most prominent in the precordial leads ($V_2-V_4$). [1] This occurs because high extracellular potassium increases the speed of repolarization (Phase 3 of the action potential) by increasing the conductance of potassium channels. **Analysis of Incorrect Options:** * **Short PR interval:** Incorrect. Hyperkalemia actually causes **PR interval prolongation** due to slowed AV conduction. [1] As levels rise further, the P wave eventually flattens and disappears (sinoventricular rhythm). * **Prolonged QT interval:** Incorrect. Hyperkalemia typically causes a **shortened QT interval** because the rapid repolarization shortens the action potential duration. Prolonged QT is a hallmark of *hypokalemia* or *hypocalcemia*. * **Widening of QRS complex:** Incorrect. While this is a classic sign of hyperkalemia, it occurs **later** (usually at $K^+ > 6.5$ mEq/L) than T wave changes. [1] It signifies delayed intraventricular conduction. **High-Yield Clinical Pearls for NEET-PG:** * **Sequence of Changes:** Tall T waves $→$ PR prolongation/P wave flattening $→$ QRS widening → "Sine wave" pattern → Ventricular Fibrillation/Asystole. [1] * **The "Sine Wave":** This is a pre-terminal rhythm where the widened QRS merges with the T wave. * **Treatment Priority:** If ECG changes are present, the first step is **Calcium Gluconate** (10%) to stabilize the cardiac membrane, even before measures to lower potassium are started. [2]

Question 976: Which is the most common benign cardiac rhythm?

A. Atrial premature contraction (Correct Answer)
B. Atrial fibrillation
C. Ventricular premature contraction
D. Ventricular tachycardia

Explanation: Atrial premature contractions (also known as Premature Atrial Complexes or PACs) are the most common benign cardiac arrhythmias encountered in clinical practice [2]. They are characterized by an early P-wave with a morphology different from the sinus P-wave, usually followed by a narrow QRS complex. They occur frequently in healthy individuals and are often asymptomatic, triggered by factors like stress, caffeine, alcohol, or tobacco. While they can occur in structural heart disease, their presence in a normal heart is considered a benign finding requiring no specific treatment. **Why other options are incorrect:** * **B. Atrial Fibrillation:** This is the most common *sustained* arrhythmia, but it is not considered "benign" [3]. It carries a significant risk of thromboembolism (stroke) and heart failure, requiring anticoagulation and rate/リズム control [3]. * **C. Ventricular Premature Contraction (VPC):** While very common and often benign in healthy hearts, VPCs are statistically less frequent than APCs in the general population. Furthermore, VPCs in the setting of structural heart disease (e.g., post-MI) carry a higher prognostic risk compared to APCs. * **D. Ventricular Tachycardia:** This is a potentially life-threatening "malignant" arrhythmia that can lead to hemodynamic collapse or progress to ventricular fibrillation. **NEET-PG High-Yield Pearls:** * **Most common arrhythmia overall:** Atrial Premature Contractions. * **Most common sustained arrhythmia:** Atrial Fibrillation [3]. * **Most common arrhythmia in Digoxin toxicity:** Ventricular Bigeminy (though Paroxysmal Atrial Tachycardia with block is the most characteristic) [1]. * **Most common arrhythmia post-MI:** Ventricular Premature Contractions (VPCs). * **Management of asymptomatic APCs:** Reassurance and avoidance of precipitants (caffeine/stress). Beta-blockers are used only if the patient is highly symptomatic.

Question 977: Cardiomegaly is seen in which of the following conditions?

A. Multivalvular disease
B. Anemia
C. Pericardial effusion
D. All of these (Correct Answer)

Explanation: Cardiomegaly refers to an enlargement of the heart, which can be identified clinically (displaced apex beat) or radiologically (Cardiothoracic ratio >0.5 on a PA view chest X-ray). It can result from true myocardial hypertrophy/dilation or from fluid accumulation mimicking an enlarged heart [1]. **Analysis of Options:** * **Multivalvular Disease:** Chronic valvular lesions (like Mitral Regurgitation or Aortic Regurgitation) lead to volume and pressure overload [2,3]. This results in compensatory chamber dilation and hypertrophy to maintain cardiac output, leading to significant cardiomegaly [2]. * **Anemia:** Chronic severe anemia is a **high-output state**. To meet the body's oxygen demands, the heart increases stroke volume and heart rate. Over time, this chronic volume overload leads to eccentric hypertrophy and ventricular remodeling, causing cardiomegaly. * **Pericardial Effusion:** While the heart muscle itself may not be enlarged, fluid accumulation in the pericardial sac creates the radiological appearance of a "globular" or "water-bottle" heart [4]. In clinical exams and radiology, this is categorized under the causes of an increased cardiothoracic ratio [4]. **Conclusion:** Since all three conditions result in an enlarged cardiac silhouette or true chamber enlargement, **Option D** is the correct answer. **Clinical Pearls for NEET-PG:** 1. **Water-bottle heart:** Classic radiological sign of large pericardial effusion [4]. 2. **Apex Beat:** In true cardiomegaly, the apex beat is usually displaced downwards and laterally. In pericardial effusion, the apex beat is often muffled or non-palpable. 3. **High-Output Failure:** Other causes include Thyrotoxicosis, Beriberi (Vit B1 deficiency), and AV fistulas. 4. **Cor Bovinum:** Refers to a "massive" heart (usually >500g), most commonly seen in severe Aortic Regurgitation [2].

Question 978: Heart block is seen in which of the following electrolyte imbalances?

A. Hypermagnesemia (Correct Answer)
B. Hypomagnesemia
C. Hypernatremia
D. Hypocalcemia

Explanation: **Explanation:** **Hypermagnesemia (Correct Answer):** Magnesium acts as a natural calcium channel blocker and a potent depressant of the neuromuscular and cardiac conduction systems. Elevated serum magnesium levels (>5–10 mEq/L) lead to a progressive delay in cardiac conduction. It causes prolongation of the PR interval, widening of the QRS complex, and an increase in the QT interval. At very high levels (>10–15 mEq/L), it can result in high-grade **Atrioventricular (AV) block** and eventually cardiac arrest in diastole. **Why other options are incorrect:** * **Hypomagnesemia:** Typically causes cardiac irritability rather than conduction block. It is associated with PVCs, SVT, and most characteristically, **Torsades de Pointes** (due to QT prolongation) [2]. * **Hypernatremia:** Sodium imbalances primarily affect the central nervous system (causing altered mental status or seizures) rather than the cardiac conduction system. * **Hypocalcemia:** The hallmark ECG finding is **QT interval prolongation** (specifically the ST segment). While it can rarely predispose to arrhythmias, it does not typically cause heart block; hypercalcemia is more associated with a shortened QT interval. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperkalemia** is the most common electrolyte cause of heart block (look for tall peaked T waves and loss of P waves) [1]. * **Magnesium Toxicity Treatment:** The immediate antidote is **IV Calcium Gluconate**, which antagonizes the membrane effects of magnesium. * **Therapeutic Magnesium:** Used in Eclampsia and Torsades de Pointes; loss of deep tendon reflexes (DTRs) is the earliest sign of toxicity (7–10 mEq/L).

Question 979: Which one of the following cardiac lesions is at highest risk of occurrence of infective endocarditis?

A. Atrial septal defect
B. Mitral valve prolapse without regurgitation
C. Valvular aortic regurgitation (Correct Answer)
D. Mitral stenosis

Explanation: The risk of **Infective Endocarditis (IE)** is primarily determined by the degree of turbulence caused by high-velocity blood flow [1]. High-velocity jets damage the endocardium, leading to the deposition of fibrin and platelets (Non-Bacterial Thrombotic Endocarditis), which serves as a nidus for bacterial colonization. **1. Why Valvular Aortic Regurgitation (AR) is the Correct Answer:** Aortic Regurgitation involves a high-pressure gradient between the aorta and the left ventricle during diastole. This creates significant turbulence and high-velocity jets that strike the endocardium. According to the traditional classification of IE risk, **Aortic Valve disease (both AR and AS)** and **Mitral Regurgitation (MR)** are considered high-risk lesions [1]. **2. Analysis of Incorrect Options:** * **Atrial Septal Defect (ASD):** This is considered **negligible risk**. The pressure gradient between the left and right atria is low, resulting in low-velocity flow that rarely damages the endocardium. (Note: VSD is high risk due to high-velocity shunting). * **Mitral Valve Prolapse (MVP) without Regurgitation:** MVP without an associated murmur of regurgitation is considered **low risk**. The risk only increases significantly if there is associated mitral regurgitation or thickened leaflets. * **Mitral Stenosis (MS):** Pure Mitral Stenosis is associated with a **low-to-moderate risk**. The flow across a stenotic mitral valve is relatively low-velocity compared to regurgitant lesions or aortic stenosis. **NEET-PG High-Yield Pearls:** * **Highest Risk Lesions:** Prosthetic heart valves, previous history of IE, Cyanotic congenital heart disease (unrepaired), and Coarctation of aorta. * **Intermediate Risk:** Bicuspid aortic valve, Mitral Regurgitation, Aortic Stenosis/Regurgitation, and VSD. * **Prophylaxis Update:** Current AHA/ESC guidelines recommend antibiotic prophylaxis **only** for high-risk patients (e.g., prosthetic valves, prior IE) undergoing dental procedures involving gingival manipulation [2]. It is no longer recommended for routine valvular lesions like AR or MR [2].

Question 980: A double apical impulse is a clinical finding that can be heard in which of the following conditions?

A. Myocardial infarction
B. Tricuspid regurgitation
C. Aortic stenosis (Correct Answer)
D. Cardiac tamponade

Explanation: **Explanation:** A **double apical impulse** (or bifid apex beat) refers to a palpable presystolic pulsation followed by the normal systolic thrust. **Why Aortic Stenosis (AS) is correct:** In severe Aortic Stenosis, the left ventricle (LV) faces a high pressure overload, leading to **concentric LV hypertrophy**. This results in a stiff, non-compliant ventricle. To assist with ventricular filling against this resistance, the left atrium contracts vigorously. This forceful atrial contraction (atrial kick) creates a palpable **S4 (presystolic impulse)** just before the main systolic outward thrust of the apex, resulting in a double apical impulse. **Analysis of Incorrect Options:** * **Myocardial Infarction (MI):** While an MI can cause a dyskinetic apical impulse (a "bulge" during systole), it typically presents with a faint or displaced impulse due to heart failure, rather than a classic double impulse. * **Tricuspid Regurgitation (TR):** TR primarily affects the right side of the heart. It is associated with a hyperdynamic right ventricular heave and a prominent 'v' wave in the jugular venous pulse, not a double apical impulse. * **Cardiac Tamponade:** This condition results in **Beck’s Triad** (hypotension, JVD, muffled heart sounds). The apex beat is typically characteristically **faint or impalpable** due to the fluid insulating the heart from the chest wall. **Clinical Pearls for NEET-PG:** * **Triple Apical Impulse:** Pathognomonic for **Hypertrophic Obstructive Cardiomyopathy (HOCM)**. It consists of a palpable S4 plus a double systolic outward thrust (due to midsystolic obstruction). * **Sustained Apex Beat:** Seen in pressure overload states like AS and Hypertension. * **Hyperdynamic/Displaced Apex:** Seen in volume overload states like Aortic Regurgitation (AR) and Mitral Regurgitation (MR).

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Cardiology — MCQs

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