Freedom R M, Bini R, Dische R, Rowe R D
Eur J Cardiol. 1978 Aug;8(1):27-50.
The morphological features of 23 patients with straddling or overriding mitral valve are presented. Levocardia was present in 20 of 23; visceroatrial situs solitisu in 20 of 23, with 3 patients, 2 with asplenia and 1 with polysplenia, having visceral heterotaxia. A concordant D-ventricular loop was present in the 20 patients with visceroatrial situs solitus. Six of these had double outlet right ventricle; 2 had asplenia syndrome; 1 had D-transposition of the great arteries, ventricular defect and pulmonary atresia; 1 with tricuspid atresia and double outlet-outlet chamber; 1 with polysplenia syndrome; and 12 had endocardial cushion defect with marked underdevelopment of the left ventricle, and normally related great arteries. Left ventricular size was related to the amount of mitral valve (or left-sided component of a common atrioventricular valve) connected to it. In those patients in whom little effective mitral orifice was connected to the left ventricle, the left ventricle was diminutive. Endocardial fibroelastosis of the left ventricle was noted in only a single patient. Six of the 7 patients with double outlet right ventricle (including one with double outlet bulbus) had subpulmonary obstruction, and in one of these, this was related in part to the straddling mitral valve. In 1 patient with double outlet right ventricle, there was a double orifice mitral valve, and it was the accessory mitral orifice that straddled. The diagnosis of overriding mitral valve should be suspected in any patient with significant conotruncal anomalies and underdeveloped left ventricle, especially the patient with double outlet right ventricle, and in the patient with endocardial cushion defect, hypoplasia of the left ventricle, and obstructive anomalies of the aortic arch. In certain patients, selective left atriography, left ventriculography, and single and two dimensional echocardiography may be diagnostic of this condition.
本文呈现了23例骑跨或跨越二尖瓣患者的形态学特征。23例患者中20例心脏左位；23例中有20例心房内脏位置正常，3例患者存在内脏异位，其中2例无脾，1例多脾。20例心房内脏位置正常的患者存在协调一致的D型心室袢。其中6例为右心室双出口；2例为无脾综合征；1例为大动脉D型转位、室间隔缺损和肺动脉闭锁；1例为三尖瓣闭锁和双出口-出口腔；1例为多脾综合征；12例为心内膜垫缺损，左心室明显发育不全，且大动脉关系正常。左心室大小与连接至左心室的二尖瓣（或共同房室瓣的左侧部分）的数量相关。在那些与左心室相连的有效二尖瓣口较小的患者中，左心室较小。仅1例患者发现左心室心内膜纤维弹性组织增生。7例右心室双出口患者（包括1例双出口球囊）中有6例存在肺下梗阻，其中1例部分与骑跨二尖瓣有关。在1例右心室双出口患者中，存在双孔二尖瓣，且是副二尖瓣口骑跨。对于任何有明显圆锥干异常和左心室发育不全的患者，尤其是右心室双出口患者，以及心内膜垫缺损、左心室发育不全和主动脉弓梗阻性异常的患者，均应怀疑存在跨越二尖瓣。在某些患者中，选择性左心房造影、左心室造影以及一维和二维超声心动图可能有助于诊断这种情况。
