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Optimizing muscle-to-cardiac timing for aortomyoplasty
D R Thompson1, B L Cmolik, E A Cheever
1Division of Cardiothoracic Surgery, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4929, USA.
Biomedical Sciences Instrumentation
|January 1, 1997
Summary
Optimizing aortomyoplasty involves precise muscle stimulation timing. Synchronizing latissimus dorsi muscle contraction with the cardiac cycle maximizes diastolic augmentation and improves heart support.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Cardiac Physiology
Background:
- Aortomyoplasty is a surgical technique using the latissimus dorsi muscle for diastolic counterpulsation in heart failure.
- The effectiveness of aortomyoplasty may depend on the precise timing of muscle stimulation relative to the cardiac cycle.
Purpose of the Study:
- To investigate the impact of muscle-to-cardiac timing on the hemodynamic outcomes of aortomyoplasty.
- To determine the optimal timing for latissimus dorsi muscle stimulation during diastole for enhanced counterpulsation.
Main Methods:
- The study utilized a canine model (n=9, 20-25 kg).
- Aortomyoplasty was performed, and the latissimus dorsi muscle was stimulated.
- Muscle stimulation was initiated at the dicrotic notch, with systematic variations in stimulus duration to assess hemodynamic effects.
Main Results:
- Maximum mean diastolic aortic pressure was achieved when muscle stimulation terminated at the R-wave.
- Peak left-ventricular pressure was minimized when stimulation ended before the R-wave.
- The endocardial-viability ratio was maximized when stimulus termination coincided with the R-wave.
Conclusions:
- Muscle-to-cardiac timing significantly influences the effectiveness of counterpulsation in aortomyoplasty.
- Optimal timing of latissimus dorsi muscle stimulation is crucial for maximizing diastolic augmentation and improving hemodynamic performance.