CASE 1
An 18-year-old male patient was diagnosed as rheumatic heart disease with severe AR and MR. He was on enalapril as vasodilator preoperatively. Pulse was irregular and collapsing. He was scheduled for valve replacement surgery. Preinduction radial arterial line was inserted. Arterial waveform was peculiar — one greater amplitude peak was followed by one lesser amplitude peak alternately [Figure 1]. This was mimicking pulsus alternans.
Figure 1.
Arterial waveform with alternate greater and lesser amplitude wave (marked by yellow arrow)
CASE 2
A 60-year-old male patient after coronary artery bypass grafting was having large and small amplitude arterial waveform [Figure 2]. This waveform was appearing as pulsus alternans.
Figure 2.
Bigeminy ECG rhythm with alternate greater and lesser amplitude wave (marked by yellow arrow)
Pulsus alternans is generally seen in left ventricle dysfunction. In case 2, ECG rhythm was bigeminy. Every normal QRS was giving rise to normal arterial pulse wave and every premature ventricular contraction was corresponding to lower amplitude arterial wave. This pattern created pulsus alternans. In case 1, as patient was already vasodilated, there was peripheral run off. So diastolic phase of arterial pulse is prolonged, appearing as 2nd lower amplitude arterial wave. This lower amplitude wave did not correspond to QRS in ECG. Such a waveform can be misdiagnosed as pulsus alternans.