Intraoperative Bypass Flow Measurement Reduces the Incidence of Post-operative Ventricular Fibrillation and Myocardial Markers After Coronary Revascularisation

Abstract: Objective
Sudden ventricular fibrillation (VF) and myocardial infarction (MI) are life-threatening complications after coronary artery bypass grafting (CABG). We prospectively analysed the impact of intraoperative bypass flow measurement with the transit time flow Doppler method (TTFD) on the incidence and outcome of postoperative VF and MI.

Methods
‍In 1995 a standardized algorithm for the treatment of postoperative VF was introduced in our institution. The rate of postoperative VF was therefore exactly registered. In 1998 the TTFD method was implemented as a standard in all CABG cases. Whenever insufficient bypass graft flow was detected, anastomoses were redone and technical problems affecting the grafts were excluded. The incidence of postoperative VF and CK/CK-MB fraction was observed prospectively and the new data was compared to the data from 1995 to 1998.

Results
From 1/95 to 7/98 a total of 4321 patients (group A) were operated on with isolated CABG procedures using extracorporeal circulation. In the period from 8/98 to 10/02 a total of 3421 patients (group B) was operated on with isolated CABG procedures under the same conditions, except that the TTFD method was used in every case. The treatment of VF was standardised in both groups according to the algorithm. The most striking effect was the significant reduction of VF from 0.66% to 0.44% when TTFD was introduced and the steep decrease in mortality from 30% to 12.2% in patients with VF when the algorithm and TTFD were routinely applied. Furthermore the rate of insufficient bypass flow detected by angiography was reduced by 66%.

Conclusions
Routinely the use of TTFD significantly reduced the incidence of postoperative VF, postoperative CK/CK-MB fraction, and angiographically detected bypass malfunction.

A simultaneously implemented algorithm reduced the mortality with VF after CABG. The consequent use of TTFD intraoperatively reduced the incidence of postoperative anastomosis and technically related complications of bypass surgery and led to a significant reduction of postoperative mortality in CABG procedures.