Atrial fat pad modification during cardiac surgery: immediate effects on cardiovascular variability parameters

Postoperative atrial fibrillation (PAF) is one of the most significant complications in patients following open heart surgery. Atrial fat pad modification (AFPM) emerged as a new, promising method to reduce this complication. The following study was performed to assess the immediate effects of this technique on cardiovascular variability parameters.

In 16 patients undergoing various types of open heart surgery, location of the fat pads was defined by delivery high frequency stimulation at multiple epicardial sites. Areas leading to >30% slowing in heart rate were correlated to the corresponding fat pad. CM-1 hemostatic sealant was injected into the epicardial atrial fat pads to neutralize conduction pathways. Noninvasive blood pressure and ECG were recorded for 30-min-periods before and 24h after surgery. Following data preprocessing, heart rate variability (HRV), blood pressure variability (BPV), baroreflex sensitivity (BRS) and nonlinear dynamics of heart rate and blood pressure were calculated. Data of treated patients were compared to a historical database of 140 patients without AFPM.

There was a clear and significant decrease of most HRV and BRS parameters immediately after surgery in both groups, while BPV-parameters had a tendency to increase. NLD-analyses revealed an overall reduction in the complexity in cardiovascular dynamics. AFPM-patients, however, showed preserved short term HRV after surgery as expressed by RMSSD, (p<0.01) and pNN10 (p<0.01).

AFPM obviously has significant impact on cardiovascular autonomic function in patients undergoing cardiac surgery. From the present data, an effect on both sympathetic and vagal nerve system seems likely.