SUPRAVENTRICULAR TACHYCARDIA AND SYNCOPE IN HYPERTROPIC CARDIOMYOPATHY

晕厥是肥厚型心肌病患者的常见症状， 在许多患者中可能是由室性心动过速引起的，原因是 心输出量下降。室上性心动过速总体情况良好 左心室正常的患者可以耐受，很少会导致 晕厥。观察室上性心动过速对心脏功能的影响 肥厚型心肌病，心率150的快速心房起搏是 对25例老年高血压患者进行平均血压测量 肥厚型心肌病21例，左心功能正常。 对12例急性心肌梗死患者心脏大静脉的冠脉流量进行了评估 肥厚型心肌病和8例左心室正常的患者，均 心外膜冠状动脉正常。与患有 左心室正常，肥厚型心肌病患者 显示在快速心房时全身血压显著下降 快步走。这可能与舒张期缩短导致的前负荷下降有关。 顺应性失调者的充盈期与协调房收缩功能丧失 脑室在Starling曲线的上升支上运行，结果 在中风的工作中摔倒了。血压的下降也导致了 冠脉流量显著下降，这可能导致心肌缺血和左 心功能不全。因此，室上性心动过速，由 快速心房起搏可能是许多人晕厥前和晕厥的原因 肥厚型心肌病患者。

Syncope is a frequent symptom in patients with hypertrophic cardiomyopathy, and may be caused by ventricular tachycardia in many patients, due to a fall in cardiac output. Supraventricular tachycardia is generally well tolerated by patients with normal left ventricles, and rarely results in syncope. To examine the effect of supraventricular tachycardia in hypertrophic cardiomyopathy, rapid atrial pacing at a heart rate of 150 was performed with measurement of mean blood pressure in 25 patients with hypertrophic cardiomyopathy and 21 patients with normal left ventricles. Coronary flow was estimated in the great cardiac vein in 12 patients with hypertrophic cardiomyopathy and 8 patients with normal left ventricles, all with normal epicardial coronary arteries. In comparison to patients with normal left ventricles, patients with hypertrophic cardiomyopathy demonstrated a marked fall in systemic blood pressure during rapid atrial pacing. This may relate to a fall in preload due to shortened diastolic filling period and loss of coordinated atrial systole in a noncompliant ventricle operating on an ascending limb of the Starling curve, resulting in a fall in stroke work. The fall in blood pressure also resulted in a marked fall in coronary flow, which may cause myocardial ischemia and left ventricular dysfunction. Thus, supraventricular tachycardia, simulated by rapid atrial pacing, may account for presyncope and syncope in many patients with hypertrophic cardiomyopathy.