Cardiology Practice Questions

Q: At what serum potassium level does a sine wave pattern typically appear on an ECG?

> 8 mEq/dl. ### Explanation Hyperkalemia is a life-threatening electrolyte abnormality that causes progressive changes in cardiac conduction. The correct answer is **> 8 mEq/L** because the "sine wave" pattern represents the final stage of intraventricular conduction delay before cardiac arrest. **The Progression of ECG Changes:** 1. **5.5 – 6.5 mEq/L:** The earliest sign is **tall, peaked T-waves** (narrow base, "tent-shaped") due to rapid repolarization [1]. 2. **6.5 – 8.0 mEq/L:** As potassium rises, the atrial myocardium becomes paralyzed, leading to **loss of P-waves** (atrial standstill) [1]. Simultaneously, the QRS complex begins to widen [1]. 3. **> 8.0 mEq/L:** Extreme widening of the QRS complex causes it to merge with the T-wave. This creates a smooth, undulating, biphasic rhythm known as the **sine wave pattern**. If untreated, this progresses rapidly to ventricular fibrillation or asystole [1]. **Analysis of Incorrect Options:** * **Option A (> 6 mEq/L):** Associated with peaked T-waves and initial PR interval prolongation, but not sine waves. * **Option B (> 7 mEq/L):** Typically characterized by the disappearance of P-waves and significant QRS widening, but the distinct sine wave morphology usually requires higher levels [2]. * **Option D (> 10 mEq/L):** While a sine wave will certainly be present, this level is often incompatible with life; the pattern typically manifests earlier, around the 8–9 mEq/L range. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment Priority:** The first step in management when ECG changes are present is **Calcium Gluconate** (10 ml of 10% solution) to stabilize the myocardial membrane [2]. It does *not* lower serum potassium. * **Pseudohyperkalemia:** Always rule out hemolysis during blood collection or thrombocytosis/leukocytosis if ECG is normal despite high lab values. * **Causative Drugs:** ACE inhibitors, ARBs, Spironolactone, and NSAIDs are common culprits in boards.

Q: ST elevation and hyperacute T waves in precordial leads V1 to V6 and in lead aVL indicates:

Anterolateral wall MI. ### Explanation **1. Why Anterolateral Wall MI is Correct:** The ECG findings described (ST elevation and hyperacute T waves) represent an acute ST-elevation myocardial infarction (STEMI) [1]. To localize the infarct, we look at the specific leads involved: * **V1–V4:** Represent the **Anterior wall** (supplied by the Left Anterior Descending artery - LAD) [2]. * **V5–V6, I, and aVL:** Represent the **Lateral wall** (supplied by the Left Circumflex artery - LCX or diagonal branches of the LAD) [1], [2]. Since the ST elevation spans from **V1 to V6** (Anterior + Lateral) and includes **aVL** (Lateral), it indicates an **Anterolateral wall MI**. This typically suggests a proximal occlusion of the **Left Main Coronary Artery** or a very proximal **LAD**. **2. Why Other Options are Incorrect:** * **Posterior Wall MI:** Characterized by ST *depression* and tall R waves in V1–V3 (reciprocal changes). Diagnosis is confirmed by ST elevation in posterior leads V7–V9. * **Inferior MI:** Characterized by ST elevation in leads **II, III, and aVF** [1]. It usually involves the Right Coronary Artery (RCA). * **Lateral Wall MI:** Isolated lateral MI involves only leads I, aVL, V5, and V6. Since V1–V4 (anterior leads) are also involved here, "Anterolateral" is the more accurate and comprehensive diagnosis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Septal MI:** Leads V1–V2 [2]. * **Anterior MI:** Leads V3–V4 [1], [2]. * **Extensive Anterior MI:** Leads V1–V6, I, and aVL. * **Reciprocal Changes:** Look for ST depression in II, III, and aVF when viewing an Anterolateral MI; this reinforces the diagnosis of STEMI [1]. * **Hyperacute T waves:** These are the *earliest* ECG sign of MI, appearing even before ST elevation.

Q: The treatment of acute myocardial infarction includes which of the following?

All of the above. **Explanation:** The management of Acute Myocardial Infarction (AMI) focuses on immediate reperfusion, prevention of further clot formation, and long-term ventricular remodeling. **1. Aspirin:** This is the first-line antiplatelet therapy [1]. It irreversibly inhibits cyclooxygenase-1 (COX-1), preventing the formation of Thromboxane A2. Administering 300-325 mg of crushed/chewed aspirin immediately reduces mortality in the acute phase. **2. Heparin:** Anticoagulation is essential to maintain the patency of the infarct-related artery and prevent re-occlusion or systemic thromboembolism [1]. Unfractionated Heparin (UFH) or Low Molecular Weight Heparin (LMWH) is used as an adjunct to fibrinolysis or during Primary Percutaneous Coronary Intervention (PCI). **3. ACE Inhibitors:** These are started within the first 24 hours (provided the patient is hemodynamically stable). They prevent "ventricular remodeling"—the structural changes in the heart muscle post-MI—thereby reducing the risk of heart failure and long-term mortality. **Why "All of the above" is correct:** The standard "MONA" (Morphine, Oxygen, Nitrates, Aspirin) regimen has evolved [1]. Current guidelines emphasize the combination of antiplatelets (Aspirin/Clopidogrel), anticoagulants (Heparin), and mortality-reducing drugs like ACE inhibitors and Beta-blockers. **Clinical Pearls for NEET-PG:** * **Mortality Benefit:** Aspirin, Beta-blockers (long-term), ACE inhibitors, and Statins are the primary drugs proven to reduce mortality post-MI. * **Nitrates:** Provide symptomatic relief (preload reduction) but do **not** improve mortality. They are contraindicated in Right Ventricular MI. * **Gold Standard:** Primary PCI is the preferred reperfusion strategy if performed within 120 minutes of first medical contact [2].

Question 1

At what serum potassium level does a sine wave pattern typically appear on an ECG?

Accepted Answer

> 8 mEq/dl

Answer

> 6 mEq/dl

Answer

> 7 mEq/dl

Answer

> 10 mEq/dl

Question 2

Which of the following is NOT a feature of a complete heart block?

Accepted Answer

Heart rate increase during exercise

Answer

Bradycardia

Answer

Cannon waves

Answer

Varying intensity of the first heart sound

Question 3

ST elevation and hyperacute T waves in precordial leads V1 to V6 and in lead aVL indicates:

Accepted Answer

Anterolateral wall MI

Answer

Posterior wall MI

Answer

Inferior MI

Answer

Lateral wall MI

Question 4

A 46-year-old smoker presents to the emergency department with sharp, left-sided chest pain that is not focal. Physical examination reveals no specific findings. The pain is neither aggravated nor relieved by postural changes or inspiration. An ECG shows anterior ST elevation. What should be the next step in management?

Accepted Answer

Urgent bedside echocardiogram to rule out regional wall motion abnormality

Answer

Activation of the primary angioplasty team

Answer

Await troponin tests and administer analgesia

Answer

Administer non-steroidal anti-inflammatory analgesia

Question 5

A 59-year-old woman with a 10-year history of type 2 diabetes mellitus presents with bilateral pitting edema of the ankles and feet. She also reports shortness of breath on exertion and orthopnea, using 3 pillows at night to sleep comfortably. A chest X-ray shows pulmonary venous congestion and interstitial edema. Which of the following physiologic mechanisms is most likely the immediate cause of the pulmonary edema?

Accepted Answer

Elevated pulmonary capillary pressure

Answer

Damage to endothelial cells

Answer

Damage to the epithelial lining of the alveoli

Answer

Low serum albumin

Question 6

Fixed splitting of the second heart sound (S2) may be seen in all of the following conditions except?

Accepted Answer

Left bundle branch block

Answer

Pulmonary embolism

Answer

Pulmonary stenosis

Answer

Atrial septal defect

Question 7

The treatment of acute myocardial infarction includes which of the following?

Accepted Answer

All of the above

Answer

Aspirin

Answer

Heparin

Answer

ACE inhibitors

Question 8

A 35-year-old farmer presents with recurrent episodes of chest pain. His elder brother had similar complaints and died suddenly at age 40. The farmer was advised to take nitroglycerin sublingually during pain episodes, but he finds that the intensity of pain increases with nitroglycerin. What is the most probable diagnosis?

Accepted Answer

Hypertrophic obstructive cardiomyopathy.

Answer

Subacute bacterial endocarditis involving the aortic valve.

Answer

Degenerative mitral regurgitation.

Answer

Chronic Type A dissection of aorta.

Question 9

A 68-year-old woman with hypertension and dyslipidemia presents with 30 minutes of retrosternal chest pain radiating to her neck. She is diaphoretic and in moderate distress. The ECG shows ST-segment elevation in the inferior leads. Which of the following mechanisms is the most likely cause of her condition?

Accepted Answer

coronary plaque rupture

Answer

aortic inflammation

Answer

pericardial inflammation

Answer

vasculitis

Question 10

Cardiovascular causes of digital clubbing include all of the following EXCEPT:

Accepted Answer

Aortic Dissection

Answer

Infective Endocarditis

Answer

Arteriovenous Fistulas

Answer

Tricuspid Atresia

Cardiology — MCQs

Cardiology — MCQs

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