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[Myocardial protection: is retrograde equal to antegrade perfusion?]
M Tönz1, A U Freiburghaus, F Redha
1Departement für Chirurgie, Universitätsspital Zürich.
Insights
Retrograde cardioplegia adequately perfuses the left ventricle but poorly perfuses the right ventricle. This study questions the effectiveness of retrograde cardioplegia for right ventricular myocardial protection due to inadequate and non-uniform delivery.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Myocardial Protection
Background:
- The efficacy of retrograde cardioplegia for myocardial protection is debated.
- Ensuring adequate delivery of cardioplegic solution to all cardiac regions is crucial for preventing ischemia-reperfusion injury.
Purpose of the Study:
- To evaluate the adequacy of retrograde cardioplegic solution delivery to the right ventricle compared to antegrade delivery.
- To assess the distribution and uniformity of myocardial perfusion with both antegrade and retrograde cardioplegia methods.
Main Methods:
- Bovine hearts were used in 11 experiments.
- India ink solution was infused retrogradely into the coronary sinus (n=7) and antegrade into the aortic root (n=4).
- Computer-aided morphometric analysis quantified myocardial perfusion in 11 ventricular slices.
Main Results:
- Antegrade infusion achieved 95% left ventricular (LV) perfusion, while retrograde infusion achieved 94% LV perfusion.
- Retrograde infusion resulted in significantly lower right ventricular (RV) perfusion (45%) compared to antegrade infusion (93%).
- Retrograde RV perfusion was non-uniform, with basal segments poorly perfused (16%) compared to apical segments (82%).
Conclusions:
- Retrograde cardioplegia provides adequate myocardial protection for the left ventricle and septum.
- The markedly inadequate and non-uniform delivery of retrograde cardioplegia to the right ventricle raises concerns about its protective quality.
- Further research is needed to optimize right ventricular cardioplegic delivery strategies.
Abstract:
The adequacy of retrograde delivery of cardioplegic solution to the right ventricle ist controversial. To evaluate this issue, we excised the plegic heart in 11 bovine experiments and infused an India ink solution (10 ml of India ink in 300 ml NaCl 0.9%) into the coronary sinus (n = 7) at a pressure of 60 cm H2O and into the aortic root (n = 4) at a pressure of 120 cm H2O. After fixation, the ventricles were cut in 11 transversal slices. The portion of coloured (= perfused) ventricular myocardium was calculated with computer-aided morphometric analysis. With antegrade infusion, 95 +/- 5% (mean +/- standard deviation) of the left ventricular volume (left ventricular free wall plus interventricular septum) was stained, with retrograde infusion 94 +/- 3%. Perfusion of the right ventricle was significantly lower with retrograde infusion (antegrade infusion 93 +/- 8%, retrograde 45 +/- 13%, p < 0.001), especially in the basal segments (basal vs. apical: 16 +/- 26% vs. 82 +/- 5%, p < 0.001). The adequate delivery of retrograde infusion to the left ventricle and septum allows good left ventricular myocardial protection with retrograde cardioplegia. Because the retrograde delivery to the right ventricle is markedly inadequate and nonuniform, the quality of right ventricular protection with retrograde cardioplegia has to be questioned.