Akosah K O, Funai J T, Porter T R, Jesse R L, Mohanty P K
Hunter Holmes McGuire Veterans Affairs Medical Center, Medical College of Virginia/Virginia Commonwealth University, Richmond 23249.
Chest. 1995 Mar;107(3):690-6. doi: 10.1378/chest.107.3.690.
A high incidence of embolic phenomena is associated with atrial fibrillation (AF) and the left atrial appendage (LAA) is frequently the source of the emboli. Thrombus formation may be due to stasis within the fibrillating and inadequately emptying LAA. Because LAA emptying in AF may be the result of mechanical compression by the adjacent left ventricle, it is possible that left ventricular diastolic filling duration will importantly influence passive emptying of the LAA. We hypothesized that the magnitude of emptying of the LAA in AF is related to the duration of left ventricular diastolic filling which is determined by the ventricular response rate in AF.
The objective of our study was to determine the relationship of ventricular response rate in AF to LAA emptying and to assess the influence of sinus rhythm and heart rate on LAA emptying immediately after direct current cardioversion to sinus rhythm.
To study this, we used transesophageal echocardiography to measure LAA ejection fraction ([LAAmax-LAAmin]/LAAmax x 100%) and evaluated its relationship to left ventricular response rate (VRR) in 26 patients with AF (mean age, 65 +/- 7 [1 SD] years).
There was a strong inverse relationship between LAA ejection fraction and VRR in AF (r = -0.73; p < 0.001). LAA ejection fraction during AF was 26 +/- 10%, and immediately after successful cardioversion, it increased to 46 +/- 12% (p < 0.001). However, during sinus rhythm there was no relationship between LAA ejection fraction and VRR (r = 0.06; p = NS) in the subgroup of patients who were successfully converted to sinus rhythm. There were poor relationships between LAA ejection fraction and peak transmitral flow velocity (r = -0.41; p = NS) or pulmonary venous flow velocity (r = -0.03; p = NS) in AF.
These results indicate that the magnitude of LAA emptying in AF is strongly and inversely influenced by ventricular rate. Direct current cardioversion to sinus rhythm is associated with an increase in the magnitude of LAA emptying that is not influenced by heart rate. The magnitude of LAA emptying may be an important factor in the formation of thromboemboli in AF. The extent to which controlling the VRR in chronic AF will prevent stasis and LAA thrombus formation remains to be determined.
栓塞现象的高发生率与心房颤动（AF）相关，左心耳（LAA）常常是栓子的来源。血栓形成可能是由于颤动且排空不充分的左心耳内血液淤滞所致。由于房颤时左心耳排空可能是相邻左心室机械压迫的结果，左心室舒张期充盈时间很可能会对左心耳的被动排空产生重要影响。我们推测，房颤时左心耳的排空程度与左心室舒张期充盈时间有关，而左心室舒张期充盈时间由房颤时的心室反应率决定。
我们研究的目的是确定房颤时心室反应率与左心耳排空的关系，并评估直流电转复为窦性心律后，窦性心律和心率对左心耳排空的影响。
为研究此问题，我们采用经食管超声心动图测量26例房颤患者（平均年龄65±7[标准差1]岁）的左心耳射血分数（[LAAmax - LAAmin]/LAAmax×100%），并评估其与左心室反应率（VRR）的关系。
房颤时左心耳射血分数与VRR之间存在强烈的负相关（r = -0.73；p < 0.001）。房颤时左心耳射血分数为26±10%，成功转复后立即升至46±12%（p < 0.001）。然而，在成功转复为窦性心律的患者亚组中，窦性心律时左心耳射血分数与VRR之间无相关性（r = 0.06；p =无统计学意义）。房颤时左心耳射血分数与二尖瓣血流峰值速度（r = -0.41；p =无统计学意义）或肺静脉血流速度（r = -0.03；p =无统计学意义）之间相关性较差。
这些结果表明，房颤时左心耳排空程度受心室率的强烈负向影响。直流电转复为窦性心律与左心耳排空程度增加相关，且不受心率影响。左心耳排空程度可能是房颤时血栓栓塞形成的一个重要因素。在慢性房颤中控制VRR预防血液淤滞和左心耳血栓形成的程度仍有待确定。
