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Atrial cardiomyoplasty in a Fontan circulation
Bernhard Voss1, Falk-Udo Sack, Werner Saggau
1Department of Cardiac Surgery at the German Heart Centre of Munich, Lazarettstrasse 36, 80636 Munich, Germany. voss@dhm.mhn.de
Summary
Right atrial cardiomyoplasty (ACMP) using the latissimus dorsi (LD) muscle shows potential for improving Fontan circulation hemodynamics. The study found ACMP provided hemodynamic benefit, particularly when an inferior vena cava (IVC) valve was implanted.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Experimental Medicine
Background:
- The Fontan circulation, a palliative surgical procedure for single-ventricle physiology, connects systemic veins directly to the pulmonary artery, leading to passive pulmonary flow.
- Increased pulmonary vascular resistance can compromise Fontan circulation, making atrio-pulmonary connections prone to failure.
Purpose of the Study:
- To investigate the potential of right atrial cardiomyoplasty (ACMP) using the latissimus dorsi (LD) muscle to enhance pulmonary flow in an experimental Fontan circulation model.
- To assess the hemodynamic effects of ACMP in an animal model with elevated pulmonary vascular resistance.
Main Methods:
- A Fontan circulation model was created in 19 Foxhounds under cardiopulmonary bypass.
- The left latissimus dorsi (LD) muscle was transferred into the chest, wrapped around the right atrium (RA), and stimulated synchronously with the cardiac cycle.
- Two groups were studied: Group 1 (11 dogs) had an inferior vena cava (IVC) valve implanted and pulmonary inflow impedance increased; Group 2 (8 dogs) did not have an IVC valve but had flowmeters in the IVC and superior vena cava (SVC).
Main Results:
- In Group 1, LD stimulation significantly increased right atrial pressure (RA), pulmonary atrial pressure (PAP), central venous pressure, stroke volume, and peak conduit flow.
- A pulsatile pressure/flow profile was achieved in the PA-conduit with 1:1 LD stimulation, and muscle relaxation did not impede RA filling at higher frequencies.
- In Group 2, LD stimulation resulted in backflow into the IVC and SVC, leading to a less pronounced increase in pulmonary artery pressure/flow.
Conclusions:
- Right atrial cardiomyoplasty (ACMP) can achieve 'ventricularization' of the RA by utilizing the contractile force of the latissimus dorsi (LD) muscle.
- The hemodynamic benefits of ACMP in this experimental Fontan model were contingent upon the implantation of an IVC valve.