BACKGROUND Resolution of left ventricular outflow tract (LVOT) obstruction predicts symptom relief postmyectomy. Intraoperative measurement of LVOT gradients thus is essential for surgical guidance. We hypothesized that (1) hypertrophic cardiomyopathy patients have lower LVOT gradients when measured intraoperatively with transesophageal echocardiography (TEE) compared with preoperative measurements with transthoracic echocardiography (TTE) and that (2) intraoperative provocative testing can help evaluate the adequacy of surgical resection. METHODS We compared resting LVOT gradients on preoperative TTE to intraoperative TEE. We also compared intraoperative resting and provoked gradients pre- and postresection. Either isoproterenol 10 μg/kg/min or dobutamine 20 μg/kg/min was used. Patients with provoked LVOT gradients >30 mm Hg were considered for further resection based on LVOT/mitral valve morphology and clinical comorbidities. RESULTS Of 315 patients identified, 293 patients were included in the analysis. There was a statistically significant difference between preoperative TTE and intraoperative TEE resting LVOT gradients (60.9 ± 39.4 mm Hg vs 42.0 ± 30.5 mm Hg, P < .0001). Out of 197 patients who had significant resting obstruction preoperatively, 82 (41.6%) demonstrated mild or no dynamic obstruction under general anesthesia. Provocative testing with both isoproterenol and dobutamine increased peak gradients (116.8 ± 33 mm Hg isoproterenol vs 107.5 ± 33 mm Hg dobutamine, P = .03). Post-cardiopulmonary bypass, seven patients (2.3%) had LVOT gradients > 30 mm Hg at rest, while 63 patients (21.5%) had residual gradients >30 mm Hg only with provocation. Elevated gradients, persistent systolic anterior motion of the mitral valve with near contact, and/or significant mitral regurgitation with provocative testing resulted in return to cardiopulmonary bypass in 41 patients (14%). CONCLUSIONS Resting intraoperative TEE LVOT gradients are significantly lower than preoperative TTE gradients, with systolic anterior motion of the MV and outflow obstruction often not visualized after inducing general anesthesia. Intraoperative pharmacologic provocation can identify patients who may benefit from further surgical intervention, facilitating procedural success.

中文翻译：

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梗阻性肥厚型心肌病患者行隔肌切除术的术中挑衅性测试。

背景技术左心室流出道（LVOT）梗阻的缓解可预测肌瘤切除术后症状缓解。因此，术中测量LVOT梯度对于手术指导至关重要。我们假设（1）与经胸超声心动图（TTE）术前测量相比，经食道超声心动图（TEE）术中测量时肥厚型心肌病患者的LVOT梯度较低，并且（2）术中刺激性测试可帮助评估手术切除的充分性。方法我们比较了术前TTE与术中TEE的静息LVOT梯度。我们还比较了术前和术后的术中静息和诱发梯度。使用异丙肾上腺素10μg/ kg / min或多巴酚丁胺20μg/ kg / min。LVOT梯度异常的患者> 根据LVOT /二尖瓣形态和临床合并症，考虑进一步切除30 mm Hg。结果在确定的315例患者中，有293例被纳入分析。术前TTE与术中TEE静息LVOT梯度之间存在统计学差异（60.9±39.4 mm Hg vs 42.0±30.5 mm Hg，P <.0001）。在197例术前有明显静息阻塞的患者中，有82例（41.6％）在全身麻醉下表现为轻度或无动态阻塞。异丙肾上腺素和多巴酚丁胺的刺激性测试增加了峰梯度（116.8±33 mm Hg异丙肾上腺素与107.5±33 mm Hg多巴酚丁胺，P = .03）。心肺旁路手术后，有7例患者（2.3％）的静息时LVOT梯度> 30 mm Hg，而63例患者（21.5％）的残余梯度> 30毫米汞柱仅在有挑衅时。梯度升高，二尖瓣近距离接触持续性收缩期前向运动和/或通过刺激性测试显着的二尖瓣关闭不全导致41例患者重新回到体外循环（14％）。结论静息的术中TEE LVOT梯度明显低于术前TTE梯度，诱发全身麻醉后通常不可见MV的收缩前运动和流出道梗阻。术中药理学挑衅可以确定可能从进一步的手术干预中受益的患者，从而促进手术的成功。和/或进行刺激性试验的二尖瓣关闭不全导致41例患者（14％）恢复体外循环。结论静息的术中TEE LVOT梯度明显低于术前TTE梯度，诱发全身麻醉后通常不可见MV的收缩前运动和流出道梗阻。术中药理学挑衅可以确定可能从进一步的手术干预中受益的患者，从而促进手术的成功。和/或进行刺激性试验的二尖瓣关闭不全导致41例患者（14％）恢复体外循环。结论静息的术中TEE LVOT梯度明显低于术前TTE梯度，诱发全身麻醉后通常不可见MV的收缩前运动和流出道梗阻。术中药理学挑衅可以确定可能从进一步的手术干预中受益的患者，从而促进手术的成功。