Author/Editor		Zupan, I; Rakovec, P; Budihna, N; Brecelj, A; Koželj, M
Title		Tachycardia induced cardiomyopathy in dogs; relation between chronic supraventricular and chronic ventricular tachycardia
Type		članek
Source		Int J Cardiol
Vol. and No.		Letnik 56
Publication year		1996
Volume		str. 75-81
Language		eng
Abstract		Long-standing ventricular tachycardia (VT) and supraventricular tachycardia (SVT) can produce a reversible left vertricular dysfunction. The onset of cardiomyopathy and the severity of posttachycardic changes depend at least on three parameters of tachycardia, including its type (VT or SVT), rate and duration. Ten dogs (beagles) were paced at 180 beats/min for 3 weeks. Two pacing modalities, supraventricular and ventricular, were used in each dog. In half of them, the study was started by ventricular, and in the other half by supraventricular high-rate pacing. The alternate pacing modality was applied after complete recovery of left ventriciular function. Ventricular function and moorphology ware evalutated by radionuclidie ventriculography, echocardiography and Swan-Ganz catheterisation. Posttachycardic changes were studied in sinus rhythm after cessation of pacing. Left ventricular ejection fraction (LVEF) fell significantly after either type of tachycardia (SVT: 53+-5%, VT: 48+-7%, P less th.0.05) compared with baseline values (69.5+-2.3%). Significant increases (P less th.0.05) in end-systolic (SVT: 2.1+-0.3 cm, VT:2.4+-0.2 cm vs. 1.6+-0.3 cm) and end-diastolic dimensions (SVT: 3.0+-0.3 cm, VT: 3.3+-0.4 cm vs. 2.7+-0.3 cm) indicated ventricular dilation in paced animals. Left ventricular pulmonary capillary wedge pressure increased significantly after either type of tachycardia as compared with baseline values (SVT: 7.5+-1.2 mmHg, VT:8.4+-1.1 mmHg vs. 1.9+-1.5 mmHg, P less th.0.05); the difference between tachycardias was not sifnificant. The present study demonstrates that chronic SVT and VT result in left ventricular dysfunction in a relatively short time, even if the heart rate is not very high. Deterioration of left ventricular ejection fraction and dilation of the left ventricle are more marked in chronic VT than in chronic SVT.
Descriptors		MYOCARDIAL DISEASES TACHYCARDIA, SUPRAVENTRICULAR TACHYCARDIA, VENTRICULAR VENTRICULAR DYSFUNCTION, LEFT DOGS CARDIAC PACING, ARTIFICIAL CATHETERIZATION, SWAN-GANZ CHRONIC DISEASE ECHOCARDIOGRAPHY FOLLOW-UP STUDIES RADIONUCLIDE VENTRICULOGRAPHY RANDOM ALLOCATION