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

An abnormal jugular venous pressure curve with an accentuated ‘a’ wave of sufficient intensity to cause the earlobes to ‘flap’, due to decreased 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 hypertension. Cannon ‘a’ waves may be regular—as are AV junctional rhythms, in which an ‘a’ wave occurs every 2nd beat in a 2:1 block—or irregular, which is more common and may occur in complete heart blocks without atrial fibrillation, ventricular tachycardia, or AV dissociation

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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