Waxman H L, Cain M E, Greenspan A M, Josephson M E
Circulation. 1982 Apr;65(4):800-4. doi: 10.1161/01.cir.65.4.800.
The effect of increased stimulus current strength on the right ventricular effective refractory period during sustained ventricular tachycardia and on the ability of single premature right ventricular stimuli to terminate ventricular tachycardia was evaluated. Studies were performed during 53 episodes of sustained ventricular tachycardia in 25 patients. Forty-four of 53 episodes were slowed by pharmacologic therapy. Current intensities of twice diastolic threshold, 5 mA and 10 mA were used. Increasing current from twice diastolic threshold (1.52 +/- 0.66 mA) to 5 mA (32 episodes) shortened the mean ventricular effective refractory period from 213 +/- 50 to 188 +/- 43 msec (p less than 0.001); and from twice diastolic threshold (1.53 +/- 0.60 mA) to 10 mA (42 episodes), from 206 +/- 55 to 176 +/- 50 msec (p less than 0.001). There was a direct correlation between cycle length of ventricular tachycardia and the ventricular effective refractory period measured at twice diastolic threshold (r = 0.77, p less than 0.001). However, the cycle length of ventricular tachycardia and the amount of shortening of ventricular effective refractory period as current was increased were not significantly correlated (r = 0.40). Eleven episodes of ventricular tachycardia (21%) that could not be terminated by ventricular stimulation at twice diastolic threshold were terminated when increased current strength was used. The ability to terminate ventricular tachycardia was associated with a decrease in ventricular effective refractory period and long tachycardia cycle length. The mean cycle length of the 11 episodes terminated was 455 +/- 50 msec, compared with 381 +/- 63 msec in the 42 episodes not terminated at increased current.
评估了在持续性室性心动过速期间增加刺激电流强度对右心室有效不应期以及单个右心室期前刺激终止室性心动过速能力的影响。对25例患者的53次持续性室性心动过速发作进行了研究。53次发作中有44次通过药物治疗减慢。使用了两倍舒张期阈值、5 mA和10 mA的电流强度。将电流从两倍舒张期阈值（1.52±0.66 mA）增加到5 mA（32次发作）时，平均右心室有效不应期从213±50毫秒缩短至188±43毫秒（p＜0.001）；从两倍舒张期阈值（1.53±0.60 mA）增加到10 mA（42次发作）时，从206±55毫秒缩短至176±50毫秒（p＜0.001）。室性心动过速的周长与在两倍舒张期阈值时测量的右心室有效不应期之间存在直接相关性（r = 0.77，p＜0.001）。然而，室性心动过速的周长与随着电流增加右心室有效不应期的缩短量之间无显著相关性（r = 0.40）。11次（21%）在两倍舒张期阈值时不能通过心室刺激终止的室性心动过速发作，在使用增加的电流强度时得以终止。终止室性心动过速的能力与右心室有效不应期的缩短和较长的心动过速周长相关。终止的11次发作的平均周长为455±50毫秒，而在增加电流时未终止的42次发作的平均周长为381±63毫秒。
