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Effect of dynamic cardiomyoplasty on phasic coronary arterial flow velocity in canine hearts
Insights
Dynamic cardiomyoplasty improved coronary blood flow velocity, contrary to concerns about arterial compression. This surgical technique enhances cardiac function, leading to increased coronary perfusion and cardiac output.
Area of Science:
- Cardiovascular Surgery
- Cardiology
- Biomedical Engineering
Background:
- Dynamic cardiomyoplasty (DCM) is a surgical procedure to assist heart function.
- Previous studies confirmed DCM's efficacy but did not investigate its impact on coronary blood flow.
- Concerns existed that DCM might impede coronary flow due to skeletal muscle contraction.
Purpose of the Study:
- To test the hypothesis that dynamic cardiomyoplasty adversely affects coronary arterial blood flow.
- To evaluate the effect of DCM on coronary blood flow velocity during systole and diastole.
Main Methods:
- Dynamic cardiomyoplasty was performed on seven mongrel dogs using a left latissimus dorsi muscle flap.
- The muscle flap was paced synchronously with the electrocardiogram's R wave.
- A Doppler catheter in the left main coronary artery measured instantaneous flow velocity, analyzed via fast Fourier transformation.
Main Results:
- Assisted cardiac cycles showed significant increases in both systolic (26.9%) and diastolic (4.0%) peak coronary flow velocity.
- Time-velocity integrals also increased significantly during systole (20.9%) and diastole (10.0%).
- Enhanced coronary flow correlated with increased mean aortic pressure and descending aortic flow.
Conclusions:
- Dynamic cardiomyoplasty enhances coronary arterial blood flow velocity, not impedes it.
- The procedure improves cardiac function, leading to increased coronary perfusion pressure and cardiac output.
- DCM is a viable option for improving coronary circulation in cardiac conditions.
Abstract:
The usefulness of dynamic cardiomyoplasty has been demonstrated repeatedly, both experimentally and clinically. Although clinical applications of dynamic cardiomyoplasty to ischemic heart disease have been reported, its effect on the coronary blood flow has never been discussed. Therefore, we tested the hypothesis that dynamic cardiomyoplasty might adversely affect coronary arterial blood flow through compression of the coronary arteries during systolic skeletal muscular contraction and incomplete relaxation of the skeletal muscle flap during diastole. Dynamic cardiomyoplasty was performed in seven mongrel dogs with the use of a left latissimus dorsi-muscle flap, paced synchronously with the R wave of the electrocardiogram. A 3F Doppler catheter was placed in the left main trunk of the coronary artery to assess the instantaneous changes of coronary flow velocity by fast Fourier transformation analysis, We compared systolic and diastolic properties during assisted versus unassisted cardiac cycles by calculating the peak velocity and the time-velocity integral. During assisted cardiac cycles, a significant enhancement of coronary arterial blood flow velocity was demonstrated by significant increases in both systolic and diastolic peak velocity (26.9% +/- 6.5%, p < 0.005; 4.0% +/- 1.6%, p < 0.05, respectively) and time-velocity integral (20.9% +/- 4.8%, p < 0.05; 10.0% +/- 4.6%, p < 0.05, respectively). Enhancement of coronary arterial blood flow velocity was associated with an increase in mean aortic pressure (16.4% +/- 1.3%, p < 0.005) and descending aortic flow (67.5% +/- 5.3%, p < 0.005). Also, the improved systolic coronary arterial blood flow velocity was consistent with an increase in systolic aortic pressure (15.8% +/- 1.5%, p < 0.005), and enhancement of diastolic coronary arterial blood flow velocity was associated with an increase in diastolic aortic pressure (8.6% +/- 2.3%, p < 0.01). We concluded that coronary arterial blood flow velocity was increased by the enhancement of cardiac function as a result of dynamic cardiomyoplasty, leading to an increase of coronary perfusion pressure and cardiac output.
