Constant-pressure coronary artery perfusion during aortic valve operations

Area of Science:

• Cardiovascular Physiology
• Cardiac Surgery
• Biomedical Engineering

Background:

• Understanding coronary blood flow dynamics is crucial during cardiac surgery, particularly aortic valve replacement.
• Traditional roller pump perfusion may alter the physiological relationship between coronary perfusion pressure and blood flow.
• The pulsatile nature of the working heart contrasts with the steady-flow characteristics of mechanical pumps.

Purpose of the Study:

• To theoretically evaluate and experimentally compare coronary blood flow under roller pump versus gravity-driven perfusion.
• To investigate the impact of different perfusion methods on coronary blood flow and pressure relationships.
• To provide evidence supporting the theoretical differences between steady-flow pump perfusion and physiological flow.

Main Methods:

• Theoretical analysis of coronary blood flow and perfusion pressure in working versus pump-perfused hearts.
• Measurement of instantaneous pressure and flow in the left coronary artery of 8 patients undergoing aortic valve replacement.
• Comparison of perfusion using a roller pump system versus a gravity flow system.

Main Results:

• Theoretical models predicted reduced endocardial blood flow with steady pump perfusion due to pressure variations.
• Mean left coronary blood flow was significantly higher with gravity perfusion (297 ml/min) compared to roller pump perfusion (153 ml/min).
• Experimental results supported the theoretical predictions regarding differences in perfusion methods.

Conclusions:

• Gravity perfusion systems demonstrate a greater mean coronary blood flow than roller pump systems during aortic valve replacement.
• The findings support the hypothesis that steady-flow pump perfusion alters normal coronary hemodynamics.
• These differences have implications for optimizing myocardial perfusion strategies in cardiac surgery.