Anomalous papillary muscle insertion into the mitral valve leaflet in hypertrophic obstructive cardiomyopathy: a lip nevus sign in echocardiography

Jian Liu; Tong Tan; Peijian Wei; Jianrui Ma; Lishan Zhong; Hailong Qiu; Shengwen Wang; Jian Zhuang; Wei Zhu; Huiming Guo; Jimei Chen

doi:10.3389/fcvm.2023.1292142

Anomalous papillary muscle insertion into the mitral valve leaflet in hypertrophic obstructive cardiomyopathy: a lip nevus sign in echocardiography

Front Cardiovasc Med. 2023 Dec 6:10:1292142. doi: 10.3389/fcvm.2023.1292142. eCollection 2023.

Authors

Jian Liu^#^{1

2}, Tong Tan^#^{1

2

3}, Peijian Wei^#^{1

2}, Jianrui Ma^{1

2}, Lishan Zhong⁴, Hailong Qiu^{1

2}, Shengwen Wang^{1

2}, Jian Zhuang^{1

2}, Wei Zhu⁴, Huiming Guo^{1

2}, Jimei Chen^{1

2}

Affiliations

¹ Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China.
² Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangzhou, Guangdong, China.
³ Beijing Anzhen Hospital, Capital Medical University, Beijing Institute of Heart, Lung and Blood Vascular Diseases, Beijing, China.
⁴ Division of Adult Echocardiography, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Guangzhou, China.

^# Contributed equally.

Abstract

Background: Anomalous papillary muscle (APM) insertion into the mitral valve leaflet is rare but clinically important in hypertrophic obstructive cardiomyopathy (HOCM). In this study, we report the detection rate of APM insertion into the mitral valve using preoperative imaging modalities and the surgical outcomes of the patients.

Methods: By retrospectively reviewing the clinical records of patients with HOCM who underwent surgical treatment by a single operation group at our center from January 2020 to June 2023, patients with APM insertion into the mitral valve leaﬂet were identified. Baseline data, image characteristics, and surgical outcomes were analyzed.

Results: The incidence of APM insertion into the mitral valve leaﬂet was 5.1% (8/157). The insertion site was located at A3 in six cases, which was more common than at A2 (n = 2). Preoperative echocardiography was used to identify two patients (25%) with APM insertion. We observed a particular echocardiographic feature for APM in HOCM patients, which was noted as a "lip nevus sign", with a higher detection rate (62.5%). All patients successfully underwent septal myectomy with concomitant APM excision or mitral valve replacement via the transaortic (n = 5) or transmitral (n = 3) approach. The mean age was 49.0 ± 17.4 years and seven patients (87.5%) were female. Interventricular septum thickness (17.0 mm vs. 13.3 mm, P = 0.012) and left ventricular outflow gradient (117.5 mmHg vs. 7.5 mmHg, P = 0.012) were significantly decreased after surgery. Residual outflow obstruction, systolic anterior motion, and ≥3+ mitral regurgitation were negative. During the follow-up of 26.2 ± 12.2 months, there were no reported operations, adverse events, mitral regurgitation aggravations, recurrences of outflow obstruction, or instances of SAM.

Conclusions: Papillary muscles inserted into the mitral valve leaﬂet are a subtype of subvalvular malformation in HOCM that requires surgical correction. The lip nevus sign on echocardiography is a characteristic of APM insertion in HOCM and may improve the preoperative detection rate. Adequate myectomy with anomalous papillary muscle excision has achieved good results in reducing the outflow gradient and eliminating mitral regurgitation, with good outcomes at short-to-intermediate follow-up.

Keywords: anomalous papillary muscles; echocardiography; hypertrophic obstructive cardiomyopathy; imaging modalities; subvalvular malformation; surgical outcomes.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article.