Ranasinghe Isuru, Ayoub Chadi, Cheruvu Chaitu, Freedman Saul B, Yiannikas John
Department of Cardiology & The University of Sydney, Sydney Medical School, Level 3 West, Concord Repatriation General Hospital, Hospital Road, Concord, Sydney, NSW 2139, Australia.
Department of Cardiology & The University of Sydney, Sydney Medical School, Level 3 West, Concord Repatriation General Hospital, Hospital Road, Concord, Sydney, NSW 2139, Australia.
Int J Cardiol. 2014 May 15;173(3):487-93. doi: 10.1016/j.ijcard.2014.03.078. Epub 2014 Mar 20.
Isolated basal septal hypertrophy (IBSH) of the left ventricle (LV) is not a well understood phenomenon, particularly in the presence of concomitant left ventricular outflow tract obstruction (LVOTO). We evaluated the prevalence of IBSH and compared those with and without LVOTO.
Retrospective observational study of 4104 consecutive patients undergoing echocardiography at a community cardiology practice and a hospital without specialized Hypertrophic Cardiomyopathy (HCM) service to determine prevalence of IBSH, defined as isolated hypertrophy (>15 mm) of the basal LV septum (BS) without hypertrophy elsewhere. Clinical, ECG and echocardiographic characteristics were compared in IBSH with and without LVOTO.
Prevalence of IBSH was 5.8% (240/4104): mean (SD) age was 76.0y (10.4) with equal gender distribution. Prevalence increased with age (p<0.001 for trend), reaching 7.8% over 70y. None had a family history of HCM, and HCM-associated ECG changes were uncommon. Mean BS thickness (SD) was 17.8mm (0.24) with a BS/posterior wall ratio (SD) of 1.76 (0.31). Resting peak LVOT gradient (>20mmHg) was present in 8/240 (3.3%), mean (SD) 69.6mmHg (59.3). Patients with LVOTO had hypercontractile LV function (fractional shortening [SD] 51.8% [9.5] vs. 40.5% [10.9], p=0.012) compared to those without LVOTO, but had similar BS thickness [SD] (17.8mm [3.0] vs. 17.8mm [2.8], p=0.996) and ECG characteristics. Greater apical and septal displacements of the mitral valve co-aptation point characterized those with IBSH and LVOTO.
IBSH is common in elderly patients referred for echocardiography. LVOTO occurs only when concomitant mitral valve co-aptation and LV hypercontractility facilitate development of a gradient, rather than through differences in the degree of BS myocardial hypertrophy.
左心室孤立性基底间隔肥厚（IBSH）是一种尚未被充分理解的现象，尤其是在合并左心室流出道梗阻（LVOTO）的情况下。我们评估了IBSH的患病率，并比较了有和没有LVOTO的患者。
对在社区心脏病诊所和一家没有专门肥厚型心肌病（HCM）服务的医院连续接受超声心动图检查的4104例患者进行回顾性观察研究，以确定IBSH的患病率，IBSH定义为左心室基底间隔（BS）孤立性肥厚（>15mm），其他部位无肥厚。比较了有和没有LVOTO的IBSH患者的临床、心电图和超声心动图特征。
IBSH的患病率为5.8%（240/4104）：平均（标准差）年龄为76.0岁（10.4），性别分布均衡。患病率随年龄增加而升高（趋势p<0.001），70岁以上人群患病率达到7.8%。无一例有HCM家族史，与HCM相关的心电图改变不常见。平均BS厚度（标准差）为17.8mm（0.24），BS/后壁比值（标准差）为1.76（0.31）。240例中有8例（3.3%）静息时左心室流出道峰值压差（>20mmHg），平均（标准差）为69.6mmHg（59.3）。与没有LVOTO的患者相比，有LVOTO的患者左心室功能呈高收缩性（射血分数[标准差]51.8%[9.5]对40.5%[10.9]，p=0.012），但BS厚度[标准差]相似（17.8mm[3.0]对17.8mm[2.8]，p=0.996），心电图特征也相似。二尖瓣对合点更大的心尖和间隔移位是IBSH和LVOTO患者的特征。
IBSH在接受超声心动图检查的老年患者中很常见。LVOTO仅在合并二尖瓣对合和左心室高收缩性促进压差形成时发生，而不是通过BS心肌肥厚程度的差异。
