Medicine — Cardiology, NMC MBBS licence examination syllabus (Nepal Medical Council).
NMC-style practice questions written for this site. They are not past questions, and no past paper has been reproduced.
1. Name the four features that make an arrhythmia unstable.
Answer: Shock, syncope, ischaemic chest pain, and heart failure. Any one of them means the rhythm is failing to perfuse the patient and treatment does not wait for the diagnosis to be refined.
2. What does a narrow QRS complex tell you about where a tachycardia originated?
Answer: That the impulse reached the ventricles through the normal conducting system, so it arose above them — supraventricular. Fast conduction through those fibres depolarises the ventricle almost simultaneously, keeping the complex narrow.
3. A patient has a regular broad-complex tachycardia and is alert with a normal blood pressure. Why is it still managed as ventricular tachycardia?
Answer: Because the alternative diagnoses are less dangerous. Treating true VT as supraventricular can cause it to degenerate, whereas the reverse error is usually recoverable — the asymmetry of the consequences justifies the assumption, not the probability of each diagnosis. Being currently stable does not exclude abrupt deterioration.
4. A patient with atrial fibrillation has a well-controlled ventricular rate and no symptoms. Does that reduce their stroke risk?
Answer: No. The stroke risk comes from blood pooling in atria that quiver rather than contract, and that continues regardless of how fast the ventricles respond. Anticoagulation is decided on the patient's risk profile, independently of rate control or symptoms.
5. An ECG shows P waves at one regular rate and QRS complexes at a slower regular rate with no relationship between them. The patient feels well. What is the rhythm and why is it urgent?
Answer: Complete heart block. The ventricles are driven by an escape rhythm, which is slow and unreliable and can stop without warning — so the patient is stable because of a mechanism that may not last. They need monitoring and urgent senior involvement despite feeling well.
6. A septic patient has a sinus tachycardia. Why would slowing the heart rate be harmful?
Answer: Because the tachycardia is an appropriate compensation — cardiac output is the product of rate and stroke volume, and the raised rate is maintaining perfusion in the face of vasodilatation and reduced filling. Removing it removes the compensation. The treatment is the sepsis.
7. Give three reversible causes worth excluding in any new arrhythmia, and say why each matters.
Answer: Potassium disturbance, because both high and low levels disturb the membrane excitability every heartbeat depends on. Drugs — including antiarrhythmics themselves, digoxin toxicity, stimulants and thyroid excess. And ischaemia, hypoxia or sepsis, where the rhythm is a response to a problem elsewhere. Treating the trace without the cause means it returns.
8. Why is second degree block with progressively lengthening PR intervals generally less concerning than second degree block with dropped beats and a constant PR?
Answer: Because the progressive pattern reflects fatigue in the atrioventricular node itself, which is usually stable, whereas sudden dropped beats with an unchanged PR reflect disease lower in the conducting system. Lower disease is more likely to progress to complete block, and the escape rhythms that arise below are slower and less reliable.
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