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Hemodynamic and metabolic effects of paced linkage following heterotopic cardiac transplantation
J Morris-Thurgood1, R Cowell, V Paul
1Department of Cardiology, Harefield Hospital, Middlesex, London, England.
Insights
Paced linkage in heterotopic heart transplants improves function in both donor and recipient hearts. This technique enhances cardiac output and coronary flow, potentially preventing long-term recipient heart deterioration.
Area of Science:
- Cardiovascular Surgery
- Transplantation Medicine
- Biomedical Engineering
Background:
- Heterotopic cardiac transplantation maximizes donor organ utilization.
- Recipient heart function can decline post-transplant, leading to clinical deterioration.
- Paced linkage offers a potential strategy to improve cardiac function in these patients.
Purpose of the Study:
- To evaluate the impact of paced linkage on recipient and donor heart function.
- To assess hemodynamic and metabolic changes associated with paced linkage.
- To determine the potential benefits of this technique for long-term outcomes.
Main Methods:
- The study involved 11 heterotopic heart transplant recipients.
- A pacemaker was used to synchronize recipient heart systole with donor heart diastole.
- Hemodynamic parameters were compared between baseline and paced linkage conditions.
Main Results:
- Paced linkage significantly improved total cardiac output (5.0 vs. 4.5 L/min) and recipient coronary sinus flow (278 vs. 186 mL/min).
- Recipient heart systolic performance increased, with higher left ventricular systolic pressure and improved ejection dynamics.
- Metabolic studies indicated no evidence of ischemia, and donor heart function showed reduced end-diastolic pressure and improved contractility.
Conclusions:
- Paced linkage in heterotopic cardiac transplantation yields significant functional improvements in both hearts.
- Permanent pacemaker implantation may preserve these acute benefits.
- This technique holds promise for preventing premature recipient heart deterioration.
Background And Purpose:
Heterotopic cardiac transplantation is a valuable surgical technique that maximizes the use of donor organs. However, recipient heart function may decline steadily postoperatively with resulting clinical deterioration. Paced linkage has the potential of reducing afterload and enhancing coronary flow of both hearts, thereby improving recipient- and donor-heart function. This may have long-term as well as short-term benefits.
Methods And Results:
The study was performed on 11 heterotopic transplant recipients. The two hearts were linked with a pacemaker (paced linkage) to produce recipient heart systole during different periods of donor-heart diastole. The recipient ventricular contraction was timed to occur during early, mid, and late diastole of the donor heart. Hemodynamic baseline measurements were compared with the optimal counterpulsated data. Paced linkage produced significant improvements in total cardiac output, 5.0 +/- 0.9 compared with baseline 4.5 +/- 0.8 L/min (P = .021); recipient coronary sinus flow, 278 +/- 145 versus 186 +/- 108 mL/min (P = .022); and aortic systolic pressure, 135 +/- 27 versus 123 +/- 27 mm Hg (P = .005). There was an overall improvement in systolic ventricular performance in the recipient heart when pace linked, as evidenced by a significant increase in left ventricular systolic pressure of 118 +/- 36 compared with the baseline value of 108 +/- 33 mm Hg (P = .016), an increase in ejection period from 174 +/- 30 versus 203 +/- 48 (P = .046), and a decrease in the pre-ejection period of 147 +/- 37 when paced versus 181 +/- 39 milliseconds (P = .013). The metabolic studies showed a significant decrease in hypoxanthine release from a baseline level of 0.4 mumol/L to a paced value of -0.06 mumol/L (P = .002); these very low values would suggest that there is no evidence of ischemia. Hemodynamic changes in the donor heart included a significant reduction in the left ventricular end-diastolic pressure from 6.8 +/- 4.4 versus baseline of 10.5 +/- 5.8 mm Hg (P = .029) and in maximum -dP/dT from 3.2 +/- 1.7 versus baseline of 2.1 +/- 1.1.
Conclusions:
Paced linkage after heterotopic cardiac transplant produces significant functional improvements in both hearts. Permanent pacemaker implantation may sustain these acute benefits and prevent the premature deterioration of the recipient heart.