Kaseda S, Zipes D P
Krannert Institute of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis 46202.
J Am Coll Cardiol. 1988 Jun;11(6):1327-36. doi: 10.1016/0735-1097(88)90300-2.
The purpose of this study was to investigate the immediate effects of an increase in atrial pressure on atrial refractoriness by determining the relation between the atrial pressure and effective refractory period of the atrium. In 21 open chest anesthetized dogs, after the blocking of atrioventricular (AV) conduction by formalin injection, the left atrium and left ventricle were paced sequentially at a fixed cycle length of 300 ms. The AV interval was varied from 0 to 280 ms in 20 ms steps during the recording of aortic and left atrial pressures and refractory period of the left atrium. Mean left atrial pressure was lowest (8.0 +/- 0.4 mm Hg, all values mean +/- SEM) at an AV interval of 47 +/- 3 ms, when refractory period was 135.5 +/- 2.6 ms. Mean left atrial pressure was highest (13.3 +/- 0.5 mm Hg) at an AV interval of 147 +/- 5 ms, when refractory period was 137.9 +/- 2.4 ms (p less than 0.01). Left atrial diameter measured by echocardiography increased from 33.7 +/- 1.8 mm at an AV interval of 47 ms to 37.8 +/- 1.8 mm (p less than 0.01, n = 10) at an AV interval of 147 ms, and mean aortic pressure decreased from 109 +/- 4 to 101 +/- 4 mm Hg. After surgical decentralization of vagal and sympathetic innervation to eliminate baroreflex influence on refractoriness, left atrial refractory period prolonged from 141.6 +/- 3.4 to 145.4 +/- 3.4 ms (p less than 0.01) when mean left atrial pressure increased from 9.5 +/- 0.4 to 15.2 +/- 0.6 mm Hg. A similar relation was noted between right atrial pressure and right atrial refractory period (n = 10) and between left atrial pressure and refractory period of the interatrial septum (n = 12). In six chronically instrumented conscious dogs, left atrial refractory period prolonged from 116.3 +/- 2.3 to 124.2 +/- 1.7 ms (p less than 0.01) when mean left atrial pressure increased from 4.0 +/- 0.8 to 9.0 +/- 0.3 mm Hg. Therefore, an increase in atrial pressure lengthens refractory period of both atria and the interatrial septum in anesthetized and conscious dogs.
本研究的目的是通过确定心房压力与心房有效不应期之间的关系，来研究心房压力升高对心房不应期的即时影响。在21只开胸麻醉犬中，通过注射福尔马林阻断房室（AV）传导后，以300毫秒的固定周期长度依次对左心房和左心室进行起搏。在记录主动脉和左心房压力以及左心房不应期期间，AV间期以20毫秒的步长从0变化至280毫秒。当AV间期为47±3毫秒、不应期为135.5±2.6毫秒时，平均左心房压力最低（8.0±0.4毫米汞柱，所有数值均为平均值±标准误）。当AV间期为147±5毫秒、不应期为137.9±2.4毫秒时，平均左心房压力最高（13.3±0.5毫米汞柱）（p<0.01）。通过超声心动图测量，左心房直径在AV间期为47毫秒时为33.7±1.8毫米，在AV间期为147毫秒时增加至37.8±1.8毫米（p<0.01，n = 10），平均主动脉压力从109±4降至101±4毫米汞柱。在对迷走神经和交感神经进行手术去神经支配以消除压力反射对不应期的影响后，当平均左心房压力从9.5±0.4升高至15.2±0.6毫米汞柱时，左心房不应期从141.6±3.4延长至145.4±3.4毫秒（p<0.01）。在右心房压力与右心房不应期之间（n = 10）以及左心房压力与房间隔不应期之间（n = 12）也观察到了类似的关系。在6只长期植入仪器的清醒犬中，当平均左心房压力从4.0±0.8升高至9.0±0.3毫米汞柱时，左心房不应期从116.3±2.3延长至124.2±1.7毫秒（p<0.01）。因此，在麻醉和清醒犬中，心房压力升高会延长心房和房间隔的不应期。
