Question 3.2

Created on Thu, 05/21/2015 - 09:41
Last updated on Mon, 05/14/2018 - 19:57
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Other SAQs in this paper

Other SAQs on this topic

A 65 year old man is admitted to your ICU following emergency percutaneous coronary stenting after an anterior STEMI complicated  by cardiogenic shock.

a) Comment  on the arterial waveform and describe your reasoning.

b) What are the physiologic consequences of this?

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College Answer

a) Comment  on the arterial waveform and describe your reasoning.

Arterial waveform from IABP
Early inflation of balloon (augmentation occurs before dicrotic notch) Early deflation –

b) What are the physiologic consequences of this?

Incr LV wall stress, incr myocardial 02 consumption, incr LVEDV & LVEDP, worsening of mitral regurgitation, worsening of pulmonary oedema.

Discussion

a) is straightforward. It is a pattern recognition question.

Details of IABP waveform analysis are discussed elsewhere.

b) is somewhat more tricky, but the answer can be arrived at by process of logic rather than brute memory.

The early diastolic inflation increases the afterload of the contracting ventricle, which causes it to work harder. Hence the increased O2 consumption.LV wall stress is also increased, which decreases subendocardial perfusion. End-diastolic LV pressure is increased, which increases mitral regurgitation. The failure of systolic augmentation is more of a "loss-of-benefit" father than a "gain-of-harm".

References

Krishna, Murli, and Kai Zacharowski. "Principles of intra-aortic balloon pump counterpulsation." Continuing Education in Anaesthesia, Critical Care & Pain9.1 (2009): 24-28.