cannon A wave

cannon A wave

Etymology: L, cane, tube; AS, wafian

a powerful atrial wave in the jugular venous pulse caused by the contraction of the right atrium against a closed tricuspid valve. Rapid, regular cannon A waves (the "frog sign") are diagnostic of paroxysmal supraventricular tachycardia. Irregular cannon A waves are seen in atrioventricular (AV) dissociation and are therefore especially helpful in the diagnosis of ventricular tachycardia, which includes AV dissociation in 50% of cases.

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cannon 'a' wave

Cardiology An abnormal jugular venous pressure curve with an accentuated 'a' wave of sufficient intensity to cause the earlobes to 'flap', due to ↓ right ventricular compliance, tricuspid stenosis or an arrhythmia in which the atrium contracts against a closed or stenosed tricuspid valve; a less 'explosive' but still prominent 'a' wave may by associated with pulmonary HTN; CAWs may be regular, as are AV junctional rhythms, where a CAW occurs every 2^nd beat in a 2:1 block, or irregular, which are more common and may occur in complete heart blocks without A Fib, V tach, AV dissociation