13, 11, 15, 18
Chapter 13 resolves this as a disagreement about WHICH HEART is being described, not about physics. Ch 5 reasons about the systemic circuit as a whole in a ventricle that still ejects — total flow is conserved and non-pulsatile perfusion presents lower time-averaged impedance. Ch 27 reasons about the ejection THRESHOLD in a ventricle that barely ejects — it must open the aortic valve against a root the pump is actively pressurising, and if it cannot it stops ejecting entirely. The operative variable is residual LV function. Manage as though Ch 27 is true, because its failure mode is catastrophic and Ch 5's is benign. Bedside reformulation: do not ask whether VA ECMO raises afterload; ask whether this ventricle is still ejecting and what happens to that when you change the flow.
n/a
n/a — a physiological question
Neither position is supported by outcome data; both are physiological argument in a textbook. The reconciliation offered in Chapter 13 is THIS BOOK'S REASONING, not a published reconciliation, and is labelled as such in-chapter. Resolving it properly would need pressure-volume loop studies across a range of residual LV function on VA support, relating flow to aortic valve opening and end-diastolic pressure. Red Book edition year not independently confirmed.
TWO CHAPTERS OF THE SAME TEXTBOOK STATE OPPOSITE POSITIONS. Ch 5 (Physiology of ECLS): 'Mixing of cardiac and retrograde ECLS flow does not add significantly to arterial pressure or systemic resistance. VA ECMO does not increase left ventricular afterload above normal. In fact, it decreases afterload by maintaining non pulsatile perfusion.' Ch 27 (Initiating ECLS for Adult Cardiac Failure): 'With a competent aortic valve and poor LV function, peripheral VA ECMO pressurizes the aorta resulting in proportionally excessive LV afterload, more so when right ventricular contractility is preserved. Without adequate LV ejection into the aorta, the LV overdistends, which may rapidly culminate in severe pulmonary edema, pulmonary hemorrhage, and increased risk of LV cavity and aortic root thrombosis.'
Adults on peripheral VA ECMO