Hemodynamics during Arrhythmias

Cardiac pressure waveforms are determined by the underlying cardiac rhythm. This chapter considers the right-heart hemodynamics with attention to the cardiac rhythm. It provides an example of how reliance on pressure waves of the pulmonary capillary wedge alone may be confusing, resulting in a misinterpretation of the cardiac events. Various arrhythmias can produce distorted pressure waveforms, which may be confused with benign physiologic events. The most commonly observed cardiac arrhythmia is a premature ventricular contraction (PVC). PVCs are often characterized by compensatory pauses and distorted QRS complexes. However, the QRS complex may not be easily distinguishable from a normal beat on physiologic monitors with reduced or poorquality electrocardiographic waveforms due to loose electrocardiographic leads. Such ECG tracings often require scrutiny of the associated pressure waves, since the electrocardiographic artifacts cause loss of the signal or a signal trigger for an audible beep in the laboratory of the regular rhythm.