A case of “sleeping PC” cardioversion

A 75 year old man developed sudden onset, central, crushing, chest pain at rest. He was brought into hospital by ambulance. Cardiac monitoring in the ambulance captured the onset of asymptomatic ventricular tachycardia (VT) (upper panel). Intravenous amiodarone was drawn up and about to be administered when the ambulance drove over a speed bump at 5 mph. The patient was cardioverted into sinus rhythm by the jolt from the “sleeping policeman” (lower panel). On admission to hospital the patient was in sinus rhythm but was transferred to coronary care for monitoring. The VT was asymptomatic and the patient's only recollection of the journey was the extremely bumpy ride.

A precordial thump, which produces an electrical depolarisation of 2–5 J, can cardiovert ventricular tachyarrhythmias. Coughing or Valsalva induced cardioversion has also been reported. Indeed, any acute mechanical stimulation can trigger ectopic myocardial excitation which, depending on timing and circumstance, may either initiate or terminate VT.

Thus, a correctly timed, moderate precordial mechanical impact can cause sudden arrhythmic cardiac death without causing structural damage to the heart (commotio cordis). This could be due to mechanical activation of cation selective channels and swift, impulse‐like mechanical stimulation over relatively small areas (4–5 cm) of the precordium early in the T wave are most arrhythmogenic.

In contrast, slow compression or violent shaking of the chest, as occurred in this case, is usually unable to trigger the ectopic excitation necessary for cardioversion, making this case unusual.