Effect of ventricular dilatation on defibrillation threshold in the isolated perfused rabbit heart. Export

@article{citeulike:465692, abstract = {INTRODUCTION: Ventricular dilatation has important electrophysiologic effects, but its effect on ventricular defibrillation threshold (DFT) is unknown. METHODS AND RESULTS: A fluid-filled, latex balloon was placed in the left ventricular cavity of 19 isolated rabbit hearts. In each experiment, an undilated volume (equivalent to a left ventricular end-diastolic pressure of approximately 0 mmHg) was compared to a dilated volume achieved by adding 1.0 mL of saline (n = 10) or 5\% dextrose (n = 9) to the intracavitary balloon. Left ventricular effective refractory period (ERP) and DFT were determined at each volume. Defibrillation was attempted with a monophasic shock delivered between a patch electrode positioned over the posterior left ventricle (cathode) and a metallic aortic cannula (anode). DFT was determined using a modified "down/up" protocol with 10 V steps. Ventricular dilatation increased the left ventricular end-diastolic pressure from 0 +/- 0.5 mmHg to 35 +/- 3 mmHg (P < 0.001), decreased the average left ventricular ERP 15\% (from 116 +/- 3 msec to 99 +/- 3 msec; P < 0.001), and increased the average DFT 30\% (from 96 +/- 4 V to 125 +/- 7 V; P < 0.001). In one third of experiments, the dilated DFT was > or = 150\% of the DFT at zero volume. The mechanism of the observed increase in DFT is unknown but may be related to the decrease in refractoriness observed with ventricular dilatation. CONCLUSION: Acute ventricular dilatation in this model increased DFT an average of 30\%, an effect not previously described. This observation may have implications for patients with implantable cardioverter defibrillators.}, address = {Division of Cardiology, University of Colorado Health Sciences Center, Denver 80262, USA.}, author = {Ott, P. and Reiter, M. J.}, citeulike-article-id = {465692}, citeulike-linkout-0 = {http://view.ncbi.nlm.nih.gov/pubmed/9300299}, citeulike-linkout-1 = {http://www.hubmed.org/display.cgi?uids=9300299}, issn = {1045-3873}, journal = {J Cardiovasc Electrophysiol}, keywords = {dilatation, shock}, month = {September}, number = {9}, pages = {1013--1019}, posted-at = {2006-01-15 07:50:52}, priority = {5}, title = {Effect of ventricular dilatation on defibrillation threshold in the isolated perfused rabbit heart.}, url = {http://view.ncbi.nlm.nih.gov/pubmed/9300299}, volume = {8}, year = {1997} }

TY - JOUR ID - citeulike:465692 L3 - citeulike-article-id:465692 N2 - INTRODUCTION: Ventricular dilatation has important electrophysiologic effects, but its effect on ventricular defibrillation threshold (DFT) is unknown. METHODS AND RESULTS: A fluid-filled, latex balloon was placed in the left ventricular cavity of 19 isolated rabbit hearts. In each experiment, an undilated volume (equivalent to a left ventricular end-diastolic pressure of approximately 0 mmHg) was compared to a dilated volume achieved by adding 1.0 mL of saline (n = 10) or 5% dextrose (n = 9) to the intracavitary balloon. Left ventricular effective refractory period (ERP) and DFT were determined at each volume. Defibrillation was attempted with a monophasic shock delivered between a patch electrode positioned over the posterior left ventricle (cathode) and a metallic aortic cannula (anode). DFT was determined using a modified "down/up" protocol with 10 V steps. Ventricular dilatation increased the left ventricular end-diastolic pressure from 0 +/- 0.5 mmHg to 35 +/- 3 mmHg (P < 0.001), decreased the average left ventricular ERP 15% (from 116 +/- 3 msec to 99 +/- 3 msec; P < 0.001), and increased the average DFT 30% (from 96 +/- 4 V to 125 +/- 7 V; P < 0.001). In one third of experiments, the dilated DFT was > or = 150% of the DFT at zero volume. The mechanism of the observed increase in DFT is unknown but may be related to the decrease in refractoriness observed with ventricular dilatation. CONCLUSION: Acute ventricular dilatation in this model increased DFT an average of 30%, an effect not previously described. This observation may have implications for patients with implantable cardioverter defibrillators. IS - 9 JF - J Cardiovasc Electrophysiol SN - 1045-3873 AD - Division of Cardiology, University of Colorado Health Sciences Center, Denver 80262, USA. EP - 1019 TI - Effect of ventricular dilatation on defibrillation threshold in the isolated perfused rabbit heart. VL - 8 SP - 1013 KW - dilatation KW - shock AU - Ott, P AU - Reiter, MJ PY - 1997/09// UR - http://view.ncbi.nlm.nih.gov/pubmed/9300299 ER -