Isolated right coronary lesion and anterolateral papillary muscle rupture--case report and review of the literature

Mechanical and morphometric study of mitral valve chordae tendineae and related papillary muscle

The mitral valve (MV) apparatus is a complex mechanical structure including annulus, valve leaflets, papillary muscles (PMs) and connected chordae tendineae. Chordae anchor to the papillary muscles to help the valve open and close properly during one cardiac cycle. It is of paramount importance to understand the functional, mechanical, and microstructural properties of mitral valve chordae and connecting PMs. In particular, little is known about the biomechanical properties of the anterior and posterior papillary muscle and corresponding chords. In this work, we performed uniaxial and biaxial tensile tests on the anterolateral (APM) and posteromedial papillary muscle (PPM), and their respective corresponding chordae tendineae, chordae^APM and chordae^PPM, in porcine hearts. Histology was carried out to link the microstructure and macro-mechanical behavior of the chordae and PMs. Our results demonstrate that chordae^PPM are less in number, but significantly longer and stiffer than chordae^APM. These different biomechanical properties may be partially explained by the higher collagen core ratio and larger collagen fibril density of chordae^PPM_. No significant mechanical or microstructural differences were observed along the circumferential and longitudinal directions of APM and PPM samples. Data measured on chordae and PMs were further fitted with the Ogden and reduced Holzapfel - Ogden strain energy functions, respectively. This study presents the first comparative anatomical, mechanical, and structural dataset of porcine mitral valve chordae and related PMs. Results indicate that a PM based classification of chordae will need to be considered in the analysis of the MV function or planning a surgical treatment, which will also help developing more precise computational models of MV.

Anterolateral papillary muscle rupture after intervention of the right coronary artery

Rupture of the anterolateral papillary muscle following a right coronary artery occlusion is extremely rare, and when complicated by a right ventricular infarction, can be fatal. The literature on optimal management of this complication is limited. We present an unusual case of anterolateral papillary muscle rupture following intervention of the right coronary artery.

Unusual case of acute posteromedial papillary muscle rupture after acute anterior myocardial infarction

Papillary muscle rupture is now a rare complication of acute myocardial infarction. Posteromedial papillary muscle rupture is more common than anterolateral papillary muscle rupture. The posteromedial papillary muscle is usually supplied from a branch of the right coronary artery. We present a case of posteromedial papillary muscle rupture due to an isolated left anterior descending artery lesion. This was diagnosed on the fifth day post infarction. The patient progressed to mitral valve replacement and coronary artery bypass grafting to the left anterior descending artery. We believe this unusual arterial supply to the posteromedial papillary muscle is due to an apex forming left anterior descending artery coupled with an apically located posteromedial papillary muscle.