Leerssen HM, Vos MA, Houben R, den Dulk K, Wellens HJ. High uniformity of left and right ventricular repolarization dynamics induced by an abrupt decrease in pacing cycle length in a dog is not affected by left ventricular ischemia.
J Cardiovasc Electrophysiol 2000;
11:421-9. [PMID:
10809495 DOI:
10.1111/j.1540-8167.2000.tb00337.x]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION
After an abrupt increase in heart rate, action potential duration (APD) will shorten. To assess the effect of ischemia on APD shortening dynamics, we compared right ventricular (RV) and left ventricular (LV) APD shortening induced by an abrupt decrease in pacing cycle length (PCL) during control and LV ischemia.
METHODS AND RESULTS
In eight anesthetized AV block dogs, endocardial LV and RV APD were determined simultaneously after an abrupt PCL decrease from 800 to 350 msec. Measurements were repeated during left anterior descending coronary artery (LAD) occlusion. During control, LV and RV APD shortened 97 +/- 27 and 71 +/- 14 msec, respectively (P < 0.05). Shortening was pronounced in a short initial phase and gradual in the longer secondary phase. Linear regression analysis revealed very high uniformity of LV and RV APD shortening dynamics (r2 = 0.96 +/- 0.01). During repeated LAD occlusion, ischemia induced a gradual LV APD shortening from 314 +/- 25 msec to a new steady-state value of 251 +/- 23 msec, whereas RV APD remained stable at 289 +/- 28 msec. The additional PCL decrease resulted in LV and RV APD shortening of 72 +/- 8 and 68 +/- 15 msec, respectively, with the same high uniformity of shortening dynamics as seen during control (r2 = 0.94 +/- 0.03).
CONCLUSION
There is a pronounced difference in APD shortening dynamics induced by an abrupt decrease in PCL compared with ischemia. LV shortening dynamics induced by a decrease in PCL are not affected by LV ischemia, preserving a high interventricular uniformity of repolarization dynamics.
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