Regular cannon waves vs prominent v waves or cv waves of TR

Differentiation of regular cannon waves from prominent v waves or cv waves of TR

Regular cannon waves (RCW): Cannon waves have the characteristics of a wave and are seen as flicking waves, while v waves have a surging nature. Cannon waves occur during atrial systole and have a shorter duration than the v wave of tricuspid regurgitation which occurs during ventricular systole.

Conditions causing RCW

1. Junctional tachycardia
2. Ventricular tachycardia with 1:1 retrograde conduction
3. Sinus tachycardia with first degree AV block so that atrial contraction occurs before the end of previous ventricular systole

An interesting case has been documented by Mangalachulli Pottammal Ranjith, Kayakkal Shajudeen, Sankaran Prasanth [1]. Their patient had dilated cardiomyopathy and was admitted with progressive dizziness and worsening dyspnea. ECG showed accelerated junctional rhythm with complete left bundle branch block pattern with prolongation of corrected QT interval. Video recordings of the regular jugular waves were obtained. Prominent a wave reversal was documented on pulmonary venous Doppler echocardiography. He had hypokalemia and hyponatremia at presentation, with serum potassium at 2.6 mEq/L and serum sodium at 122 mEq/L. Serum magnesium was 1.7 mEq/L. He reverted to sinus rhythm after correction of dyselectrolytemia.

Reference

1. Mangalachulli Pottammal Ranjith, Kayakkal Shajudeen, Sankaran Prasanth. Regular Cannon Wave. Indian Heart J. 2016 Sep;68 Suppl 2(Suppl 2):S291-S293.