A case of hypertrophic cardiomyopathy combined with muscular ventricular septal defect and abnormal origin of right coronary artery

Individual hypertrophic cardiomyopathy (HCM), muscular ventricular septal defect (VSD), and abnormal origin of coronary artery are common congenital heart diseases. Indeed, HCM and coronary artery anomalies have been recognized as the leading causes of exercise-related sudden cardiac death, especially among the young people. Recently, a case of HCM associated with VSD has been reported [1]. And several cases of coexistences of HCM with anomalous origin of coronary artery have also been reported [2–4]. However, concurrency of three different types of abnormalities has not been reported.

A 26-year-old man was admitted to our hospital due to atypical chest pain persisted for many years. He was diagnosed as HCM in another hospital two years ago, and had received medical therapy (angiotensin-converting enzyme inhibitors and Beta blockers) for 18 months. Physical examinations did not show abnormality. A 12-lead electrocardiogram (ECG) showed sinus bradycardia, left anterior fascicular block, T-wave anomaly, and abnormal Q wave on the leads of left ventricular anterolateral wall (Fig. 1).

2-dimensional(2D) transthoracic echocardiography(TTE)indicated hypertrophy (21 mm in diastolic phase) in the interventricular septum (Fig. 2a; Additional file 1: Movie 1). There were no detectable gradients with Doppler echocardiography in the left ventricular outflow tract at rest. However, a small defect with echo enhancement of the broken end was observed within the hypertrophic interventricular septum (Fig. 2b). Doppler echocardiography showed systolic blood flow in a specific direction from left ventricle into the interventricular myocardium (Fig. 2c, Additional file 2: Movie 2) with a peak flow speed of 1.1 to 1.3 m/s during the systolic phase (Fig. 2e). In turn, the blood flow in the opposite direction had a similar flow speed (Fig. 2d, Additional file 2: Movie 2). Contrast-enhanced echocardiography further indicated that the small defect was interlinked with the left ventricular cavity, but not with the right ventricular cavity (Fig. 2f; Additional file 3: Movie 3).

In addition, the anomalous RCA originating from left sinus of Valsalva was observed using 2D TTE (Fig. 3a, Additional file 4: Movie 4). CTA further confirmed that RCA arised from left sinus of Valsalva with an interarterial course between the aorta and pulmonary artery (Fig. 3b and c).

Syncope or family history of sudden cardiac death was not identified. But the patient’s mother, a 53-year-old woman, had been diagnosed with ventricular septal hypertrophy (17 mm in diastolic phase) in our department. Considering the expensive cost, the patient and his mother declined the genetic testing. The young patient was advised to have regular ultrasound examination and avoid intensive physical exercise.

HCM, VSD, and abnormal origin of coronary artery are common congenital heart diseases. Although HCM with VSD and HCM with anomalous origin of coronary artery have been reported [1–4], concurrencies of three types of abnormalities are rare. Our present case report provides the evidence for the coexistences of HCM, VSD and coronary artery anomalies.

Published case reports show higher prevalence of VSD with HCM in children than adult [5]. Only one case of VSD with HCM is reported in a 24-year-old female [1]. Actually, the systolic blood flow signals representing a muscular VSD have been identified within the hypertrophic ventricular septum, which was different from a coronary artery-left ventricular fistulae characterized by diastolic blood flow signals [6]. However, in our patient, the systolic blood flow speed was not as fast as the typical VSD. The unique dual direction blood flow between left ventricle and the interventricular myocardium were found using Doppler echocardiography, promoting us to further observe the difference of the patient’s VSD from common VSD. Following contrast-enhanced echocardiography, the unique small defect, i.e., the interlink with the left ventricular cavity, but not the right ventricular cavity, is very different from most of the small muscular VSDs that can close spontaneously within the first two years of life [7], suggesting that some unknown factors may be involved in the process of incomplete spontaneous closure of muscular VSD. Unfortunately, we are unable to establish any genetic association because of the lack of the genetic testing. Although HCM associated with VSD is rare in adults [1], the present case characterized by the incomplete spontaneous closure of muscular VSD in adults supports for its existence.

With increased availability of cardiac image modalities such as cardiac magnetic resonance imaging (cMRI), detection of left ventricular wall abnormalities, like myocardial clefts, is becoming more common [8–10]. Published data reveal a strong relationship between myocardial clefts and HCM. Indeed, from the morphological point of view, the crypts in the ventricular septal myocardium look similar as the VSDs with incomplete spontaneous closure. The etiology and pathogenesis of these myocardial structural abnormalities remain unclear. Taking our case into consideration, the myocardial crypts (clefts) in the interventricular septum (or part of them) could be the remnants of VSDs during spontaneous closure due to the following reasons. At first, the spontaneous closure of muscular VSD could be due to hypertrophy of the septal myocardium and/or fibrous tissue hyperplasia, etc. [7], which have been confirmed by anatomic evidence from a newborn infant with muscular VSD. In the case, fibrotic tissue replaced the defect, but gross examination revealed a small depression on the interventricular septum’s left side [11]. Secondly, Dasgupta S [12] proposed another possible mechanism for closure of muscular VSD: right ventricular endocardial tissue proliferation and coverage. In the report, a 4 mm midmuscular VSD with a left-to-right shunt in a 2-month-old female infant was observed by echocardiography. Three years later, a repeated echocardiography showed the defect’s right ventricular side was closed, but there was still a 4 mm defect in the left ventricular side. Left-to-right shunt communicating with the right ventricular cavity was not observed. This is very similar to our case. At last, Tikanoja T has reported that the incidence of muscular VSD was higher in children with HCM, but rare in adults based on clinical evidences [5]. However, these clinical observations could not be excluded from the possibility of septal myocardial hypertrophy in adults, apart from the spontaneous closure of most VSDs. With the development of modern diagnostic instruments, the remnants of these VSDs with incomplete spontaneous closure (right ventricular side closure only) shall be more easily detected.

To our knowledge, we are the first to report the HCM case accompanied with incomplete spontaneous closure of muscular VSD and anomalous RCA arising from left sinus of Valsalva, which were revealed through the combination of transthoracic 2D, color Doppler, Contrast-enhanced echocardiography and CTA. Based on our observation, HCM associated anomalies could be easily missed if examined by the single echocardiography. Therefore, the combined use of transthoracic 2D, color Doppler, contrast-enhanced echocardiography, and CTA are necessary to identify the associated congenital abnormalities of HCM.