Myocardial metabolism during fixed-rate pulsatile left ventricular bypass

Area of Science:

• Cardiovascular Surgery
• Cardiopulmonary Bypass Technology
• Myocardial Physiology

Background:

• Fixed-rate pulsatile cardiopulmonary bypass (CPB) is explored for improving subendocardial perfusion.
• Current clinical practice utilizes variable-rate pulsatile left heart bypass (LHB) asynchronous to cardiac electrical activity.
• The impact of fixed-rate pulsation on myocardial metabolism during LHB remains unclear.

Purpose of the Study:

• To investigate the effect of fixed-rate pulsatile (PLS) versus nonpulsatile (NPLS) left heart bypass on myocardial metabolism.
• To compare oxygen consumption and lactate extraction during different bypass modes.

Main Methods:

• Six adult pigs underwent alternating PLS and NPLS centrifugal pump LHB in a randomized block design.
• Coronary sinus, aortic, and bypass circuit flows were measured.
• Blood oxygen content and lactate concentrations were analyzed.

Main Results:

• Myocardial oxygen consumption decreased during NPLS but remained unchanged during PLS compared to control.
• Lactate extraction was significantly reduced during NPLS only.
• Circuit pulsation rate and pulse power index were limited by competition with the ejecting heart.

Conclusions:

• Fixed-rate pulsatile bypass is ineffective in reducing myocardial metabolism during LHB.
• Fixed-rate pulsation should be avoided in clinical left heart bypass applications.
• Optimizing bypass strategies is crucial for maintaining myocardial health during CPB.