Abstract
Background
Off-pump, multivessel, endoscopic coronary artery bypass requires cardiac displacement within an intact chest. The current study evaluated right ventricular performance and systemic hemodynamics while exposing the posterior surface of the heart using a novel, low-profile, apical suction-based cardiac positioner in a closed-chest, beating-heart model.
Methods
Six pigs underwent instrumentation with continuous monitoring of arterial pressure by fluid-filled transducer and cardiac output and coronary blood flow by ultrasound transit time flow probe. Right ventricular (RV) pressure-volume loops were generated by an impedance catheter. Heart rate was maintained between 80 and 100 beats per minute pharmacologically. The cardiac positioner displaced the heart endoscopically through a port. Data were obtained in 5 sequential phases: (1) baseline/free-beating, (2) positioner coaptation, (3) addition of Trendelenburg, (4) cardiac displacement with Trendelenburg, and (5) cardiac displacement without Trendelenburg.
Results
Cardiac displacement without Trendelenburg (Phase 5) resulted in a significant (P < 0.05) decrease in cardiac output, coronary blood flow, RV systolic pressure (RVSP), mean arterial pressure, RV end-diastolic volume (RVEDV), and RV end-systolic volume (RVESV) compared with baseline (Phase 1). With Trendelenburg added to cardiac displacement (Phase 4), all parameters improved, but only RVSP, mean arterial pressure, and RVEDV were comparable to baseline (Phase 1). There were no local complications from device coaptation.
Conclusions
The low-profile endoscopic cardiac positioner is safe and effective in the closed-chest, beating-heart porcine model. Nevertheless, cardiac displacement in a closed chest does cause impairment in ventricular performance that can be ameliorated by the addition of Trendelenburg and further technological progress.
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