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Postoperative conduction disturbances: a comparison of blood and crystalloid cardioplegia
S R Gundry1, A Sequeira, T R Coughlin
1Department of Surgery, University of Maryland Medical System, Baltimore.
Insights
Blood cardioplegia significantly increased conduction system disturbances after coronary artery bypass grafting compared to crystalloid cardioplegia. This includes higher rates of atrioventricular block and bundle-branch blocks, necessitating further investigation into myocardial protection strategies.
Area of Science:
- Cardiology
- Cardiac Surgery
- Electrophysiology
Background:
- Conduction system disturbances are known complications following cardiac surgery.
- A shift from crystalloid to blood cardioplegia was implemented based on perceived myocardial protective benefits.
- Anecdotal observations suggested an increase in conduction abnormalities post-implementation of blood cardioplegia.
Purpose of the Study:
- To compare the incidence of perioperative and late conduction system disturbances between crystalloid and blood cardioplegia.
- To evaluate the impact of different cardioplegia solutions on cardiac electrical conduction after coronary artery bypass grafting.
Main Methods:
- A retrospective analysis of patients undergoing coronary artery bypass grafting in 1987.
- Comparison of conduction disturbances in patients receiving either standard crystalloid cardioplegia or blood cardioplegia.
- Serial assessment of perioperative and late conduction abnormalities, including various types of heart block and bundle-branch blocks.
Main Results:
- Patients receiving blood cardioplegia had a significantly higher incidence of conduction disturbances (49%) compared to crystalloid cardioplegia (23%) (p < 0.001).
- Higher rates of complete heart block requiring pacing (67 vs 20), permanent atrioventricular block (12 vs 4), left bundle-branch block (28 vs 8), right bundle-branch block (68 vs 12), left anterior hemiblock (37 vs 8), and bifascicular block (23 vs 4) were observed with blood cardioplegia (all p < 0.05).
- Interventricular conduction delay was also more frequent with blood cardioplegia (53 vs 15, p < 0.005).
Conclusions:
- Blood cardioplegia, despite potential myocardial benefits, is associated with a substantially increased risk of conduction system disturbances after coronary artery bypass grafting.
- The findings challenge the routine use of blood cardioplegia without careful consideration of its electrophysiological consequences.
- Further research is warranted to optimize cardioplegia strategies for both myocardial protection and preservation of cardiac conduction.
Abstract:
Conduction system disturbances after cardioplegia are well described. Our four-man group changed in mid-1987 from standard crystalloid cardioplegia (35 mEq/L of KCl) to blood cardioplegia (4 parts blood to 1 part cardioplegia) (18 mEq/L of KCl) based on experimental and clinical evidence that blood cardioplegia provides better myocardial protection. Shortly thereafter, we anecdotally noted increased conduction abnormalities. This prompted us to compare serially all patients undergoing coronary artery bypass grafting during 1987 for perioperative and late conduction system disturbances after either crystalloid or blood cardioplegia. Surgeons and techniques including topical cooling did not differ. Forty-one (23%) of 179 patients with crystalloid cardioplegia had conduction disturbances versus 141 (49%) of 289 patients with blood cardioplegia (p less than 0.001). Perioperative complete heart block requiring atrioventricular sequential pacing occurred in 20 patients with crystalloid cardioplegia versus 67 patients with blood cardioplegia (p less than 0.002), and atrioventricular block requiring permanent pacing was present in 4 and 12 patients (p less than 0.001), respectively. Left bundle-branch block was found in 8 patients given crystalloid cardioplegia and 28 patients with blood cardioplegia (p less than 0.05); right bundle-branch block, 12 and 68 patients (p less than 0.001); left anterior hemiblock, 8 and 37 patients (p less than 0.001); and interventricular conduction delay, 15 and 53 patients (p less than 0.005), respectively. Bifascicular block occurred in 4 patients receiving crystalloid cardioplegia versus 23 receiving blood cardioplegia (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)