Abstract
Background: The effects of fibrillation/defibrillation episodes (FDEs) during defibrillator implantation
on myocardial metabolism were investigated at various defibrillation energies in patients
with different cardiac pathologies. Methods: Myocardial lactate extraction (MLE) was examined during defibrillation threshold
(DFT) testing in patients with either coronary artery disease (CAD, n = 20) or non-ischemic
cardiomyopathy (CM, n = 10). Defibrillation pulses were released 15 seconds after
induced fibrillation. A test cycle of four FDEs separated by 2-minute intervals was
applied in each case. Results: Mean MLE decreased significantly from 28±4% before FDEs to 8 ± 5% immediately after
all episodes in CAD patients, but recovered to 27 ± 7% within 2 minutes even in patients
with reduced left-ventricular function. In patients with CM mean MLE decreased markedly
from 29±3% to -11 ±3% immediately after each FDE but increased to baseline (33 ± 8%)
within the recovery period. MLE changes were independent of defibrillation energy
in all cases. Conclusions: Myocardial lactate production, suggesting cardiacischemia, was observed in patients
with CM, but not in patients with CAD. But recovery of myocardial lactate extraction
was not faster in CAD patients, indicating that the fixed FDE cycle used was well
tolerated by all patients.
Key words
Implantable cardioverter-defibrillator (ICD) - Intraoperative testing - Myocardial
lactate
