Clinical Introduction An 82-year-old man with a history of coronary artery bypass surgery, hypertension and small bowel gastrointestinal stromal tumour underwent cardiac risk evaluation prior to surgical resection of his tumour. He was asymptomatic from a cardiovascular perspective, but his activity level was less than four metabolic equivalents. Physical examination was notable for a 2/6 systolic murmur at the apex. ECG showed sinus rhythm. A transthoracic echocardiogram was performed (figure 1 and online supplementary video 1).

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Figure 1

Transthoracic echocardiography. (A) Mitral valve continuous wave Doppler and (B) tricuspid valve continuous wave Doppler.

QUESTION: The findings in figure 1 are most likely due to which of the following?

1. Atrioventricular conduction block.

2. Acute severe aortic regurgitation.

3. Patent ductus arteriosus.

4. Atrial flutter.

5. Severe mitral stenosis.