Abstract 2350: Is the Human Langendorff an Appropriate Model for the Study of Ventricular Fibrillation Dynamics?
INTRODUCTION: Though much of the information on ventricular fibrillation (VF) has been derived from VF studies in the Langendorff model, studies comparing invivo VF and exvivo VF are lacking, especially in human VF. We compared characteristics of invivo VF induced at defibrillation threshold testing (DFT), invivo VF mapped intra-operatively and VF induced in isolated human hearts (IHH).
METHODS: Sub study I: In 4 patients with ischemic cardiomyopathy, we compared activation rate of VF obtained at DFT, and VF induced in their explanted hearts post transplant (IHH). Digitised VF from DFT was compared to VF electrograms from the endocardial balloon in IHHs using a feature (half power scale distribution width) extracted from continuous wavelet transform (CWT). Sub study II: Similarly, we also compared intraoperatively mapped early VF from three left ventricular cardiomyopathic patients with the corresponding same phase of VF, exvivo in 3 explanted IHH maintained in a Langendorff system. Dominant frequency (DF) assessed by the Welsh Periodogram and the number of rotors (lasting for at least 480ms) were compared using the Student’s t-test.
RESULTS: Sub study I: Wavelet analysis showed no significant difference between DFT and IHH data (P=0.9) thus demonstrating the validity of the IHH data. VF mean cycle length (CL) was also similar between the 2 groups (224.86+ 36.15, 225.28+62.7ms, P=0.98) indicating that activation rate of VF was similar between the 2 models. Sub study II: Intraoperative DF was statistically comparable to the Langendorff DF over the endocardium (4.62+0.69, 5.03+0.82Hz, P=0.55) and over the epicardium (4.55+0.87, 5.25+0.86Hz, P=0.38). Endocardial rotor number (9.67, 13, P=0.87) was comparable between invivo and exvivo VF as was epicardial rotor number (27.3, 24, P=0.63).
CONCLUSIONS: Invivo VF induced during DFT, and exvivo VF in the same hearts post transplant, were comparable. Similarly, peroperative VF was also comparable to exvivo VF in the IHH suggesting that the human Langendorff is an appropriate model for the study of VF.