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Reducing intraoperative myocardial acidosis by continuous cardioplegic perfusion via the coronary sinus
D L Johnson1, J A Lahorra, V L Gott
1Division of Cardiac Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
Insights
Continuous retrograde coronary sinus perfusion (RCSP) effectively limits myocardial acidosis during cardiac arrest. Histidine-buffered or blood-buffered cardioplegic solutions during RCSP best preserve myocardial pH, outperforming bicarbonate solutions.
Area of Science:
- Cardiology
- Cardiothoracic Surgery
- Physiology
Background:
- Continuous retrograde coronary sinus perfusion (RCSP) offers homogeneous cardioplegic solution delivery.
- Low-pressure infusion during RCSP may limit delivery rates and prevent myocardial acidosis.
- Investigating optimal buffering strategies for RCSP is crucial for myocardial protection.
Purpose of the Study:
- To evaluate the efficacy of RCSP in limiting intraoperative myocardial acidosis.
- To compare different cardioplegic solution buffering methods during RCSP.
- To assess the impact of RCSP on myocardial pH during cardiac arrest.
Main Methods:
- Open-chest pig model with intramyocardial pH probes.
- Cardioplegic arrest induced via aortic root infusion.
- Four groups: no RCSP, bicarbonate-buffered RCSP, blood-buffered RCSP, histidine-buffered RCSP.
- 45-minute arrest period with continuous monitoring of myocardial pH.
Main Results:
- No significant baseline pH differences across groups (7.27-7.32).
- Bicarbonate-buffered RCSP (Group 2) showed higher pH (7.06) than no RCSP (Group 1, 6.74) (P<0.05).
- Histidine-buffered (7.37) and blood-buffered (7.29) RCSP preserved pre-ischemic pH levels, significantly higher than Groups 1 and 2 (P<0.05).
Conclusions:
- RCSP is effective in limiting myocardial acidosis during cardiac arrest.
- Histidine-buffered and blood-buffered cardioplegic solutions are superior to bicarbonate-buffered solutions for maintaining myocardial pH during RCSP.
- Optimized buffering agents in RCSP enhance myocardial protection during cardioplegic arrest.
Abstract:
Continuous retrograde coronary sinus perfusion (RCSP) can deliver cardioplegic solution homogeneously to the myocardium via the disease-free venous system. However, administration of cardioplegic solution through the coronary venous system necessitates low pressure infusion which may limit the rate of cardioplegic delivery. In addition, infusion of the solution at low flow rates may not prevent the development of myocardial acidosis during arrest. To determine if RCSP is capable of limiting intraoperative myocardial acidosis, open-chest pigs, monitored by intramyocardial pH probes, underwent cardioplegic arrest with a single dose aortic root infusion followed by a 45-min period of no RCSP (Group 1), RCSP of 25 mEq/liter bicarbonate-buffered cardioplegic solution (Group 2), RCSP of blood-buffered cardioplegic solution (Group 3), and RCSP of histidine-buffered cardioplegic solution (Group 4). There were no significant differences between the groups with respect to baseline pH, with a range of 7.27 to 7.32. At the end of the 45-min arrest period, Group 2 had a statistically higher pH, 7.06 +/- 0.08, compared to Group 1, 6.74 +/- 0.08 (P less than 0.05). Hearts in Groups 3 and 4 demonstrated preservation of preischemic pH levels after 45 min of arrest, 7.29 +/- 0.07 and 7.37 +/- 0.10, respectively, significantly higher than either Group 1 or 2 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)