A thumping in the chest when he lies down at night, going on for months

2026-09-12

The case

24-year-old man. A thumping in the chest when he lies down at night, going on for months

Fit, plays football twice a week and has never had symptoms while running. No blackouts. No family history of sudden death. Takes nothing; drinks little coffee.

On arrival

HR: 74
SpO₂ (%): 99
Respiratory rate: 14
Temperature (°C): 36.7
Systolic BP (mmHg): 124
Diastolic BP (mmHg): 76

Stage 1 of 1

He is well, with a normal cardiovascular examination and no murmur. A medical student is with you on the ward round and has never seen a tracing like this one.

The tracing for the quiz “A thumping in the chest when he lies down at night, going on for months”. — Twelve-lead, 25 mm/s, 10 mm/mV. Open this tracing in the studio

What does this tracing show?

ASinus bradycardia with ventricular escape beats Your answer
BSinus rhythm with atrial bigeminy Your answer
CSinus rhythm with ventricular bigeminy Correct answer Your answer
DNon-sustained ventricular tachycardia Your answer

The rhythm strip shows a repeating cycle of one narrow sinus beat followed by one wide, premature complex with no preceding P wave, producing the classic alternating pattern of ventricular bigeminy. Atrial bigeminy would show narrow premature complexes each preceded by an abnormal P wave. Non-sustained ventricular tachycardia requires three or more consecutive wide complexes, which is not what this tracing demonstrates.

The student asks where the ectopic beats are coming from. Which answer does this tracing support?

AThe atria — each ectopic beat is preceded by an early, abnormal P wave Your answer
BThe left ventricle — the ectopic QRS is dominantly positive in V1 Your answer
CThe AV junction — the ectopic QRS is narrow and identical to the sinus beats Your answer
DThe right ventricle — the ectopic QRS is dominantly negative in V1 Correct answer Your answer

A ventricular ectopic arising in the right ventricle depolarises the septum and left ventricle from right to left, producing a pattern resembling left bundle branch block: dominantly negative in V1 and positive in the lateral leads. On this tracing the ectopic complexes show a dominant S wave in V1, consistent with a right ventricular origin. A left ventricular focus would produce a dominant R wave in V1, resembling right bundle branch block morphology.

Diagnosis

Ventricular bigeminy from a right ventricular focus

The morphology of ventricular extrasystoles can sometimes reveal the ectopic focus. In this case it is an atypical LBBB pattern indicating a right ventricular focus.

Clinically it can be relevant in locating potential targets for ablative measures and a diagnostic puzzle piece in structural heart disease.

References

Latchamsetty R, Bogun F. Premature ventricular complexes and premature ventricular complex induced cardiomyopathy. Curr Probl Cardiol. 2015;40(9):379-422.
Marcus FI, McKenna WJ, Sherrill D, et al. Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria. Circulation. 2010;121(13):1533-1541.

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This tracing was generated, not recorded. It opens in the studio with every dial live.

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