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A 52-year-old woman who developed chest pain upon effort was admitted to our hospital. A grade 3/6 systolic heart murmur was heard over both sternal borders. An electrocardiogram showed sinus rhythm and right ventricular (RV) hypertrophy. Echocardiography showed a subarterial ventricular septal defect (VSD), right coronary cusp (RCC) herniation, trivial aortic valve regurgitation, and a double-chambered RV. Cardiac catheterization and angiography showed no coronary artery disease and confirmed our diagnosis. The RV was divided into 2 chambers by anomalous muscle bundles (Fig. 1A and 1B). The pressure gradient between the outlet chamber and inlet chamber of the RV was 42 mmHg, and the Qp/Qs ratio was 1.48.
The surgery, performed with the patient under cardiopulmonary bypass, included VSD closure and resection of the anomalous muscle bundles, but not aortic valvuloplasty. The postoperative course was uneventful. Cardiac catheterization and echocardiography at the 3-year follow-up visit showed successful resection of the muscle bundles and resolution of the RCC prolapse into the RV, without residual VSD or worsened aortic valve regurgitation (Fig. 1C and 1D).
Double-chambered RV is relatively rare and is usually diagnosed and repaired during childhood or adolescence; it is seldom seen in adults.1 Perimembranous VSD is the most common defect seen with double-chambered RV, and its presence is strongly associated with progressive ventricular obstruction.2 In this patient, the associated defect was a large subarterial VSD, usually seen in Asians, which can lead to aortic valve regurgitation secondary to RCC deformity and to prolapse of the RCC into the RV.3 Because the patient's cardiac anomalies were not diagnosed until she was 52 years of age, the large VSD had caused progressive RCC deformity and severe RCC prolapse into the RV at systole and diastole. The ventricular obstruction appeared to have been caused by the severely damaged RCC and the anomalous muscle bundles (Fig. 1B).
Although RV obstruction has several possible causes,4 double-chambered RV is caused specifically by anomalous muscle bundles that divide the RV.1,5 In our patient, the prolapsed RCC might well have contributed to the RV obstruction. Indeed, a good outcome was achieved by closing the VSD, which prevented further RCC prolapse into the RV, and by resectioning the anomalous muscle bundles.
Address for reprints: Haruhiko Kondoh, MD, Department of Cardiovascular Surgery, Otemae Hospital, 1-5-34, Otemae, Chuo-ku, Osaka 540-0008, Japan