Interpretation of Abnormal Arterial Line Waveforms
Arterial waveform in hypertension and peripheral vascular disease
The non-compliant vessels do not stretch in response to the systolic pressure, and thus the pressure rises rapidly at the beginning of systole, resulting in a steep systolic upstroke.
Because of the poor compliance, a powerful reflected wave is sent back to the aortic root, which when added to the systolic effort of the ventricle makes for a high peak systolic pressure.
In the elderly, the reflection wave arrives early, during systole - before the aortic valve closes- thus adding to afterload and thus to the myocardial workload; while in diastole there may be no reflection wave, which means the coronary arteries miss out on its benefit.
Other reflected waves may follow, as the pressure reverberates though the hollow woodwind arteries of this smoker.
The systolic afterload contribution from the reflected wave contribution disappears in vasodilation, and appears with vasoconstriction.
Arterial waveform in aortic stenosis
The ventricle struggles to squeeze blood though the stenosed aortic valve, and thus the systolic upstroke becomes less steep. The systolic peak may also be lower, as it is difficult to generate high aortic pressures in this condition.
The pulse pressure may be narrowed, but doesn't have to be (because the aortic stenosis may coexist with some aortic regurgitation)
Arterial waveform in aortic regurgitation
The most commonly seen feature is a widened pulse pressure; however accompanying it may be a bisferiens pulse. This second peak is a reflected wave from the strong left ventricular contraction.
Arterial waveform in left ventricular outflow tract obstruction
In HOCM, the left ventricular outflow tract may close up suddenly mid-systole. This results in a sharp drop in arterial pressure, and is demonstrated by a steep systolic decline. A strong bisferiens wave returns, causing the second peak.