Figure 32-25 Central venous pressure (CVP) changes caused by cardiac arrhythmias. A, Atrial fibrillation. Note the absence of the a wave, a prominent c wave, and a preserved v wave and y descent. This arrhythmia also causes variation in the electrocardiographic (ECG) R-R interval and left ventricular stroke volume, which can be seen in the ECG and arterial pressure (ART) traces. B, Isorhythmic atrioventricular dissociation. In contrast to the normal end-diastolic a wave in the CVP trace (left panel), an early systolic cannon wave is inscribed (asterisk, right panel). The reduced ventricular filling accompanying this arrhythmia causes decreased arterial blood pressure. C, Ventricular pacing. Systolic cannon waves are evident in the CVP trace during ventricular pacing (left panel). Atrioventricular sequential pacing restores the normal venous waveform and increases arterial blood pressure (right panel). The ART scale is shown on the left, the CVP scale on the right. (Redrawn from Mark JB: Atlas of Cardiovascular Monitoring. New York, Churchill Livingstone, 1998, Figs. 14-1, 14-5, and 14-16.)