Cohn K, Kryda W
J Electrocardiol. 1981 Jul;14(3):207-18. doi: 10.1016/s0022-0736(81)80001-5.
The potentially adverse influence of premature ectopic beats or tachyarrhythmias on cardiac performance was studied by assessing the echocardiographic left ventricular stroke volume in 21 patients with cardiac rhythm disturbances. The beat to beat stroke volume correlated closely with end-diastolic volume in each patient (average R = .9). Premature ventricular contractions decreased stroke volume by an average of 48 +/- 8 ml (-71%) compared with sinus beats; whereas the postextrasystolic beats, although preceded by a pause and higher end-diastolic volume, increased stroke volume by only 16 +/- 7 ml (18%) over the sinus beats. Those postextrasystolic beats with equivalent timing and end-diastolic volume to the sinus beats had a mean stroke volume only 8 ml higher, suggesting that postextrasystolic potentiation plays only a minor role in augmenting stroke volume. Transient aberrant ventricular conduction of intermittent left bundle branch block, ectopic beats or atrial fibrillation failed to alter stroke volume. Ventricular bigeminy, trigeminy and quadrigeminy lowered cardiac output by 1.3, .9 and .7 l/min. The onset of tachyarrhythmias was oftentimes associated with a continuously changing end-diastolic volume and stroke volume, with either alternation or progressive increment of these variables. It is apparent that premature contractions decrease stroke volume by virtue of their infringement on diastolic filing, the principle beat to be determinant of stroke volume in arrhythmias being left ventricular end-diastolic volume. Since premature beats decrease stroke volume to an extent greater than postextrasystolic beats increase it, they may reduce cardiac output by a substantial degree, depending on their frequency of occurrence and degree of prematurity.
通过评估21例心律紊乱患者的超声心动图左心室每搏输出量，研究了过早异位搏动或快速性心律失常对心脏功能的潜在不利影响。每位患者的逐搏每搏输出量与舒张末期容积密切相关（平均R = 0.9）。室性早搏使每搏输出量平均比窦性搏动减少48±8 ml（-71%）；而早搏后搏动，尽管之前有一个代偿间歇和较高的舒张末期容积，但每搏输出量仅比窦性搏动增加16±7 ml（18%）。那些早搏后搏动的时间和舒张末期容积与窦性搏动相当，其平均每搏输出量仅高8 ml，这表明早搏后增强在增加每搏输出量方面仅起次要作用。间歇性左束支传导阻滞、异位搏动或心房颤动的短暂异常心室传导未能改变每搏输出量。室性二联律、三联律和四联律使心输出量分别降低1.3、0.9和0.7 l/min。快速性心律失常的发作常常与不断变化的舒张末期容积和每搏输出量相关，这些变量会交替或逐渐增加。显然，过早收缩由于其对舒张期充盈的侵犯而降低每搏输出量，在心律失常中决定每搏输出量的主要搏动是左心室舒张末期容积。由于过早搏动降低每搏输出量的程度大于早搏后搏动增加每搏输出量的程度，它们可能会在很大程度上降低心输出量，这取决于它们的发生频率和提前程度。
