A 70-year-old man with dizzy spells has a pulse of 38/min. The ECG shows P waves and QRS complexes occurring independently. On examining the neck, intermittent giant waves are seen in the JVP. What produces these waves?

Atria contracting against a closed tricuspid valve

Backflow through a leaking tricuspid valve

Rapid filling of the right ventricle in diastole

Bulging of the closed tricuspid valve into the atrium

Cardiac cycle, ECG and heart sounds

23 NEET-PG practice questions on Cardiac cycle, ECG and heart sounds, part of Physiology. The first 23 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
A 70-year-old man with dizzy spells has a pulse of 38/min. The ECG shows P waves and QRS complexes occurring independently. On examining the neck, intermittent giant waves are seen in the JVP. What produces these waves?
1. ABackflow through a leaking tricuspid valve
2. BRapid filling of the right ventricle in diastole
3. CBulging of the closed tricuspid valve into the atrium
4. DAtria contracting against a closed tricuspid valve
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Answer: D · Atria contracting against a closed tricuspid valve
In complete heart block the atria and ventricles beat independently. Whenever an atrial contraction falls during ventricular systole, the tricuspid valve is shut, so blood is pushed back into the jugular veins, producing a cannon a wave. The irregular timing explains why they appear only intermittently. Regular cannon waves occur in junctional rhythm, where atria and ventricles contract together every beat.
- A: Tricuspid regurgitation causes large systolic v (cv) waves, not cannon a waves.
- B: Rapid ventricular filling corresponds to the y descent.
- C: Bulging of the tricuspid valve in early systole produces the small c wave.
Question 2 · Medium
During coronary angiography, the aortic pressure trace of a 50-year-old woman shows a brief notch (the incisura) on its falling limb, after which pressure declines slowly until the next beat. Which event produces this notch?
1. AOnset of atrial systole
2. BEnd of rapid ejection
3. CClosure of the aortic valve
4. DOpening of the mitral valve
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Answer: C · Closure of the aortic valve
At the end of ejection, as LV pressure falls below aortic pressure, a brief backflow of blood snaps the aortic valve shut. The sudden stop of this backflow and the recoil of the valve and aortic wall produce the incisura (dicrotic notch), which coincides with A2. It marks the end of systole and the start of isovolumetric relaxation. Afterwards, aortic pressure falls slowly through diastole as blood runs off into the periphery.
- A: Atrial systole occurs late in diastole and does not affect the aortic trace.
- B: The end of rapid ejection is not marked by a notch on the aortic trace.
- D: Mitral opening occurs later, at the end of isovolumetric relaxation.
Question 3 · Easy
A 24-year-old asymptomatic football player has a routine ECG showing a PR interval of 0.26 s; every P wave is followed by a narrow QRS complex. In which part of the conduction system does this delay mainly lie?
1. ASinoatrial node
2. BRight bundle branch
3. CAtrioventricular node
4. DPurkinje network
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Answer: C · Atrioventricular node
The PR interval, normally 0.12-0.20 s, is the time from the start of atrial depolarisation to the start of ventricular depolarisation, and most of it is spent in the AV node, where conduction is slowest. A PR above 0.20 s with every P conducted is first-degree AV block. In trained athletes it often reflects high vagal tone and is benign. It needs no treatment if the patient has no symptoms and the QRS is narrow.
- A: The SA node sets the rate and does not affect the PR interval.
- B: Bundle branch disease widens the QRS rather than lengthening the PR alone.
- D: Purkinje conduction is the fastest in the heart and adds little to the PR interval.
Question 4 · Hard
A 45-year-old woman admitted with pneumonia is receiving azithromycin and IV ondansetron. Her ECG shows a regular rhythm at 100/min with a measured QT interval of 400 ms. Using Bazett's formula, QTc = QT / square root of RR (RR in seconds; square root of 0.6 = 0.77), what is her corrected QT and how should it be judged?
1. AAbout 520 ms, prolonged
2. BAbout 400 ms, normal
3. CAbout 310 ms, short
4. DAbout 670 ms, prolonged
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Answer: A · About 520 ms, prolonged
At 100/min the RR interval is 60/100 = 0.6 s, and its square root is 0.77, so QTc = 400/0.77, about 520 ms. The measured QT looks normal only because tachycardia shortens it; corrected for rate it is clearly prolonged, and a QTc above 500 ms carries a high risk of torsades de pointes. Both drugs she is receiving can prolong the QT, so they should be reviewed, and potassium and magnesium corrected. Bazett's formula over-corrects at fast rates, but the QT is still prolonged here.
- B: 400 ms is the uncorrected QT; at 100/min it must be corrected for rate.
- C: About 310 ms comes from multiplying by the square root instead of dividing.
- D: About 670 ms comes from dividing by RR itself instead of its square root.
Question 5 · Easy
A 68-year-old woman with long-standing rheumatic mitral stenosis has a new irregularly irregular pulse. On examining her internal jugular venous pulse, which wave will be absent?
1. AThe y descent
2. BThe c wave
3. CThe v wave
4. DThe a wave
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Answer: D · The a wave
The a wave is produced by right atrial contraction at the end of diastole. In atrial fibrillation there is no coordinated atrial contraction, so the a wave disappears, and the x descent, partly due to atrial relaxation, becomes less marked. The v wave (atrial filling in systole), the c wave and the y descent (fall in pressure as the tricuspid opens) remain. The same loss of atrial contraction removes the fourth heart sound.
- A: The y descent follows tricuspid opening, which still occurs every beat.
- B: The c wave arises from ventricular systole and tricuspid valve movement, which continue.
- C: The v wave reflects atrial filling during ventricular systole and persists in AF.
Question 6 · Medium
A healthy 20-year-old medical student listens to her own heart at the left second intercostal space and notices that the second heart sound splits into two parts during deep inspiration and becomes single during expiration. Why does inspiration widen the split?
1. ALess venous return delays aortic valve closure
2. BHigher pulmonary pressure closes the valve earlier
3. CFaster heart rate shortens left ventricular ejection
4. DMore venous return delays pulmonary valve closure
Answer and explanation in LearnFree account
Question 7 · Medium
A 24-year-old woman at 30 weeks of pregnancy, known to have mild rheumatic mitral stenosis, develops acute breathlessness and frothy sputum when new atrial fibrillation raises her heart rate to 140/min. Why does the tachycardia worsen her pulmonary congestion so sharply?
1. ADiastole shortens, leaving too little filling time
2. BThe mitral orifice area falls with each faster beat
3. CSystole shortens, leaving too little ejection time
4. DLeft atrial pressure falls as the atria stop contracting
Answer and explanation in LearnFree account
Question 8 · Medium
A 40-year-old man treated for tuberculous pericarditis a year ago has ascites, pedal oedema and a raised JVP that rises further on inspiration. Chest X-ray shows pericardial calcification, and a sharp early diastolic sound is heard. Which jugular venous pattern is typical of his condition?
1. AGiant a wave with each beat
2. BLarge systolic cv wave
3. CAbsent y descent
4. DProminent, steep y descent
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Question 9 · Medium
A 58-year-old man develops acute breathlessness five days after an inferior wall myocardial infarction, with a new loud apical pansystolic murmur radiating to the axilla. A pulmonary artery catheter is placed. Which change is expected in his pulmonary capillary wedge pressure tracing?
1. AGiant v waves during ventricular systole
2. BGiant a waves at the end of diastole
3. CA wedge pressure lower than LV end-diastolic
4. DA steep, deep y descent with a plateau
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Question 10 · Medium
A 60-year-old man has an ECG in the medicine OPD. The QRS complex is mainly positive in lead I, mainly negative in lead aVF and also mainly negative in lead II. How is the mean QRS axis best described?
1. ALeft axis deviation, more negative than -30°
2. BExtreme axis, between -90° and 180°
3. CRight axis deviation, beyond +90°
4. DNormal axis, between -30° and +90°
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Question 11 · Medium
A 66-year-old hypertensive man's ECG shows QRS complexes of 150 ms, broad notched R waves in leads I and V6 and a deep broad S wave in V1. On auscultation, how is his second heart sound most likely to behave?
1. ASplit in inspiration, single in expiration
2. BWidely split, with no respiratory change
3. CSingle throughout, with a loud P2
4. DSplit in expiration, single in inspiration
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Question 12 · Medium
A 64-year-old man with long-standing hypertension and LV hypertrophy on echocardiography has a soft, low-pitched sound at the apex just before the first heart sound. He is in sinus rhythm. What produces this sound?
1. ARapid passive filling of a dilated ventricle
2. BSudden opening of a thickened mitral valve
3. CClosure of the mitral valve under high pressure
4. DAtrial contraction into a stiff ventricle
Answer and explanation in LearnFree account
Question 13 · Medium
A 72-year-old man with exertional syncope has a slow-rising carotid pulse and a harsh ejection systolic murmur at the right second intercostal space radiating to the neck, with a soft second heart sound. During cardiac catheterisation, how will left ventricular pressure compare with aortic pressure during ejection?
1. AAortic pressure exceeds LV pressure for most of ejection
2. BLV pressure far exceeds aortic pressure throughout ejection
3. CLV and aortic pressures are nearly equal throughout ejection
4. DLV pressure exceeds aortic pressure only during diastole
Answer and explanation in LearnFree account
Question 14 · Medium
A 32-year-old woman from Thrissur with rheumatic heart disease in sinus rhythm has exertional breathlessness and a mid-diastolic apical rumble preceded by an opening snap. Consider four statements on the physiology of her signs: 1. The opening snap occurs after the aortic component of the second heart sound. 2. A shorter interval between S2 and the opening snap suggests more severe stenosis. 3. A loud first heart sound means the leaflets are still mobile and widely open when systole begins. 4. The rumble is heard best with the diaphragm while she sits leaning forward. Which statements are correct?
1. A1, 2 and 3 only
2. B1 and 3 only
3. C1, 2 and 4 only
4. D2 and 4 only
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Question 15 · Medium
A 34-year-old woman with rheumatic heart disease and pulmonary hypertension has a pansystolic murmur at the lower left sternal border that becomes louder on inspiration, and a pulsatile, enlarged liver. Which pattern is expected in her jugular venous pulse?
1. AProminent x descent with a small v wave
2. BCannon a waves at irregular intervals
3. CLarge systolic cv wave with a rapid y descent
4. DAbsent a wave with a slow y descent
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Question 16 · Medium
A 25-year-old man dehydrated from acute gastroenteritis receives 2 litres of normal saline in casualty, and his venous return rises. Assuming contractility and afterload are unchanged, how will his left ventricular pressure-volume loop change?
1. AWider and shifted right, with a larger stroke volume
2. BShifted left, with a steeper end-systolic line
3. CNarrower, with a higher end-systolic volume
4. DTaller, with a smaller stroke volume
Answer and explanation in LearnFree account
Question 17 · Hard
During cardiac catheterisation of a 45-year-old man with normal valves, pressures in the left ventricle, aorta and left atrium are recorded together. For the interval from mitral valve closure to aortic valve opening, consider four statements: 1. Both mitral and aortic valves are closed and LV volume is constant. 2. The dicrotic notch appears on the aortic trace in this interval. 3. The rate of rise of LV pressure (dP/dt) reaches its peak in this interval. 4. Flow in the left coronary artery reaches its maximum in this interval. Which statements are correct?
1. A2, 3 and 4 only
2. B1 and 3 only
3. C1, 3 and 4 only
4. D1 and 2 only
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Question 18 · Hard
A 47-year-old woman with heavy alcohol use and heart failure has a cardiac MRI. Left ventricular volumes are 200 mL at end-diastole and 150 mL at end-systole, and her pulse during the scan is 90/min. What are her ejection fraction and cardiac output?
1. A25% and 18 L/min
2. B75% and 13.5 L/min
3. C33% and 4.5 L/min
4. D25% and 4.5 L/min
Answer and explanation in LearnFree account
Question 19 · Hard
The cardiology team records the left ventricular pressure-volume loop of a 30-year-old man with exertional breathlessness. The loop shows a markedly increased end-diastolic volume and stroke volume, a high peak systolic pressure, a normal vertical isovolumetric contraction segment, and no true isovolumetric relaxation segment, because LV volume starts to rise as soon as pressure begins to fall after ejection. Which valve lesion best fits this loop?
1. ASevere mitral stenosis
2. BChronic aortic regurgitation
3. CSevere aortic stenosis
4. DChronic mitral regurgitation
Answer and explanation in LearnFree account
Question 20 · Easy
A medical intern auscultates a healthy volunteer while feeling the carotid pulse and notes that the first heart sound comes just before the pulse. Which phase of the cardiac cycle begins at the first heart sound?
1. AIsovolumetric contraction
2. BIsovolumetric relaxation
3. CRapid ejection
4. DAtrial systole
Answer and explanation in LearnFree account
Question 21 · Hard
A 32-year-old man has a pansystolic murmur at the left lower sternal edge from a restrictive ventricular septal defect. Over five years he becomes cyanosed and clubbed, and the murmur fades. The second heart sound is now loud and single. Which change in haemodynamics explains the new findings?
1. ARight ventricular outflow has narrowed, as in Fallot's tetralogy
2. BPulmonary vascular resistance now exceeds systemic, reversing the shunt
3. CLeft ventricular failure has raised left atrial pressure
4. DThe defect has closed spontaneously, abolishing the shunt
Answer and explanation in LearnFree account
Question 22 · Easy
A 62-year-old man with dilated cardiomyopathy and breathlessness has a low-pitched sound in early diastole, heard best at the apex with the bell while he lies on his left side. During which phase of the cardiac cycle does this sound occur?
1. AAtrial systole
2. BReduced ventricular filling
3. CIsovolumetric relaxation
4. DRapid ventricular filling
Answer and explanation in LearnFree account
Question 23 · Medium
A 55-year-old man arrives in casualty with a hypertensive emergency, BP 230/130 mmHg. If his preload and contractility stay the same, how does his left ventricular pressure-volume loop change?
1. ATaller and narrower, with a larger end-systolic volume
2. BWider, with a larger end-diastolic volume and stroke volume
3. CShorter and wider, with a smaller end-systolic volume
4. DUnchanged in width, with a steeper end-systolic line
Answer and explanation in LearnFree account

Cardiac cycle, ECG and heart sounds

A 70-year-old man with dizzy spells has a pulse of 38/min. The ECG shows P waves and QRS complexes occurring independently. On examining the neck, intermittent giant waves are seen in the JVP. What produces these waves?

During coronary angiography, the aortic pressure trace of a 50-year-old woman shows a brief notch (the incisura) on its falling limb, after which pressure declines slowly until the next beat. Which event produces this notch?

A 24-year-old asymptomatic football player has a routine ECG showing a PR interval of 0.26 s; every P wave is followed by a narrow QRS complex. In which part of the conduction system does this delay mainly lie?

A 68-year-old woman with long-standing rheumatic mitral stenosis has a new irregularly irregular pulse. On examining her internal jugular venous pulse, which wave will be absent?

A healthy 20-year-old medical student listens to her own heart at the left second intercostal space and notices that the second heart sound splits into two parts during deep inspiration and becomes single during expiration. Why does inspiration widen the split?

A 24-year-old woman at 30 weeks of pregnancy, known to have mild rheumatic mitral stenosis, develops acute breathlessness and frothy sputum when new atrial fibrillation raises her heart rate to 140/min. Why does the tachycardia worsen her pulmonary congestion so sharply?

A 40-year-old man treated for tuberculous pericarditis a year ago has ascites, pedal oedema and a raised JVP that rises further on inspiration. Chest X-ray shows pericardial calcification, and a sharp early diastolic sound is heard. Which jugular venous pattern is typical of his condition?

A 58-year-old man develops acute breathlessness five days after an inferior wall myocardial infarction, with a new loud apical pansystolic murmur radiating to the axilla. A pulmonary artery catheter is placed. Which change is expected in his pulmonary capillary wedge pressure tracing?

A 60-year-old man has an ECG in the medicine OPD. The QRS complex is mainly positive in lead I, mainly negative in lead aVF and also mainly negative in lead II. How is the mean QRS axis best described?

A 66-year-old hypertensive man's ECG shows QRS complexes of 150 ms, broad notched R waves in leads I and V6 and a deep broad S wave in V1. On auscultation, how is his second heart sound most likely to behave?

A 64-year-old man with long-standing hypertension and LV hypertrophy on echocardiography has a soft, low-pitched sound at the apex just before the first heart sound. He is in sinus rhythm. What produces this sound?

A 34-year-old woman with rheumatic heart disease and pulmonary hypertension has a pansystolic murmur at the lower left sternal border that becomes louder on inspiration, and a pulsatile, enlarged liver. Which pattern is expected in her jugular venous pulse?

A 25-year-old man dehydrated from acute gastroenteritis receives 2 litres of normal saline in casualty, and his venous return rises. Assuming contractility and afterload are unchanged, how will his left ventricular pressure-volume loop change?

A 47-year-old woman with heavy alcohol use and heart failure has a cardiac MRI. Left ventricular volumes are 200 mL at end-diastole and 150 mL at end-systole, and her pulse during the scan is 90/min. What are her ejection fraction and cardiac output?

A medical intern auscultates a healthy volunteer while feeling the carotid pulse and notes that the first heart sound comes just before the pulse. Which phase of the cardiac cycle begins at the first heart sound?

A 32-year-old man has a pansystolic murmur at the left lower sternal edge from a restrictive ventricular septal defect. Over five years he becomes cyanosed and clubbed, and the murmur fades. The second heart sound is now loud and single. Which change in haemodynamics explains the new findings?

A 62-year-old man with dilated cardiomyopathy and breathlessness has a low-pitched sound in early diastole, heard best at the apex with the bell while he lies on his left side. During which phase of the cardiac cycle does this sound occur?

A 55-year-old man arrives in casualty with a hypertensive emergency, BP 230/130 mmHg. If his preload and contractility stay the same, how does his left ventricular pressure-volume loop change?