Peng Lillian T, Newman D Brian, Geske Jeffrey B
Mayo Clinic Alix School of Medicine, 200 1st St SW, Rochester, MN 55905, USA.
Department of Cardiovascular Medicine, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA.
Eur Heart J Case Rep. 2020 Dec 28;5(1):ytaa450. doi: 10.1093/ehjcr/ytaa450. eCollection 2021 Jan.
Left ventricular outflow tract (LVOT) obstruction is an important determinant of the management of hypertrophic cardiomyopathy (HCM). With a nationwide shortage of amyl nitrite in 2019, we implemented a 'repetitive squat-to-stand' manoeuvre to provoke LVOT obstruction during echocardiography.
A 64-year-old female was referred with symptomatic HCM refractory to pharmacologic therapy. Transthoracic echocardiography showed minor LVOT obstruction with conventional imaging at rest and during Valsalva manoeuvre, but severe obstruction was confirmed with the repetitive squat-to-stand manoeuvre. Alcohol septal ablation via the first septal perforator was performed with subsequent resolution of symptoms.
Due to the dynamic nature of LVOT obstruction, a series of provocative manoeuvres including Valsalva manoeuvre, inhalation of amyl nitrite, and exercise are often necessary to maximally augment ventricular obstruction. The recent unavailability of amyl nitrite during a nationwide shortage prompted the implementation of a protocol of repetitive squat-to-stand manoeuvre in our echocardiography laboratory. Rising from the squatting position decreases preload and afterload, both of which augment dynamic LVOT obstruction. Repetition of squatting and standing appears to enhance the sensitivity of the manoeuvre, particularly when exertional symptoms are reproduced. In this case, repetitive squat-to-stand manoeuvre led to the identification of severe LVOT obstruction which may not have been diagnosed otherwise, alteration of treatment to septal reduction therapy, and subsequent resolution of symptoms.
左心室流出道（LVOT）梗阻是肥厚型心肌病（HCM）治疗的重要决定因素。2019年全国范围内亚硝酸异戊酯短缺，我们在超声心动图检查期间实施了“反复蹲立”动作以诱发LVOT梗阻。
一名64岁女性因症状性HCM药物治疗无效前来就诊。经胸超声心动图显示，静息状态及瓦尔萨尔瓦动作时，常规成像显示轻度LVOT梗阻，但反复蹲立动作证实存在严重梗阻。通过第一间隔穿支进行酒精室间隔消融，随后症状缓解。
由于LVOT梗阻具有动态性，通常需要一系列激发动作，包括瓦尔萨尔瓦动作、吸入亚硝酸异戊酯和运动，以最大程度增加心室梗阻。近期全国性短缺期间亚硝酸异戊酯无法获取，促使我们在超声心动图实验室实施反复蹲立动作方案。从蹲位起身会降低前负荷和后负荷，二者均会加重动态LVOT梗阻。反复蹲立似乎可提高该动作的敏感性，尤其是在重现劳力性症状时。在本病例中，反复蹲立动作导致发现了严重的LVOT梗阻，否则可能无法诊断，从而改变治疗方案为间隔减容治疗，随后症状缓解。
