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Updated: Feb 1, 2026

Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice
Published on: September 17, 2015
Left ventricular outflow tract obstruction with abnormal papillary muscles.
Kotaro Oe1, Tsutomu Araki1, Miho Ohira1
1Division of Internal Medicine, Saiseikai Kanazawa Hospital, Kanazawa, Japan.
Abnormal papillary muscles causing left ventricular outflow tract obstruction can be diagnosed with cardiac magnetic resonance imaging. Medical treatment with a beta-blocker effectively managed symptoms in this case.
Area of Science:
- Cardiology
- Medical Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) can present with left ventricular outflow tract (LVOT) obstruction.
- Abnormal papillary muscles (PMs) are an uncommon cause of LVOT obstruction.
Observation:
- A 65-year-old man presented with recurrent syncope due to LVOT obstruction.
- Echocardiography and cardiac magnetic resonance (CMR) imaging revealed anteriorly displaced and accessory PMs causing systolic anterior motion (SAM) of the anterior mitral valve leaflet (AML).
Findings:
- Diagnosis of HCM with LVOT obstruction secondary to abnormal PMs was confirmed by CMR.
- Medical management with bisoprolol (2.5 mg/day) significantly reduced the LVOT pressure gradient from 56 mmHg to 24 mmHg.
Implications:
- CMR is a valuable tool for diagnosing abnormal PMs causing LVOT obstruction.
- Beta-blocker therapy can be an effective treatment for LVOT obstruction due to abnormal PMs, offering an alternative to surgery.
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