A Surgical Perspective on Ischemic Mitral Regurgitation: Tethering or Prolapse? Going Back to Papillary Muscles Anatomy. What the Surgeons Really Need to Know

Abstract

More than one third of patients with ischemic mitral regurgitation (IMR) present a valve prolapse whose mechanism is subtended by a papillary injury. The recent literature is pointing at a regional ventricular injury or wall motion abnormality rather than a global LV dysfunction as responsible for IMR and the presence of localized valve prolapse related to papillary dysfunction is additionally supporting this idea. Leaflet tethering or prolapse in these patients is subtended by lesion of the papillary muscle (PM) per se rather than its dysfunction secondary to regional and global ventricle enlargement. Identification of this type of lesion is difficult and can be overlooked. Morphological characteristics and anatomical variability of the papillary muscles determine their different susceptibility ischemic damage and dysfunction. Pioneering work in mitral anatomy shows a range of morphological diversity of PM anatomy and leads to an anatomical classification with important implications in IMR surgery. New methods of investigation, as multidetector computed tomography or magnetic resonance provide a very accurate and proper identification of the morphological pattern of the subvalvular apparatus, which is crucial for a long-lasting and successful surgical correction. The involvement of PM in the pathophysiology of IMR not only in terms of their functional anomaly, but also of their effective anatomical aspects and characteristics is increasingly emerging. The modern advancements of imaging techniques can guide the preoperative surgical planning and the surgeon needs to be aware of morphological features of the subvalvular apparatus and combine these findings with echographic functional parameters before embarking in complex mitral repairs.

Papillary Muscle Rupture following Acute Myocardial Infarction

“…Conversely, the posterior papillary muscle is more sensitive to ischemia (91% of the cases in a series by Nappi et al) because of its single blood supply. 5 TTE or TEE may demonstrate a flail mitral valve leaflet with prolapse during systole into the atrium, visualization of a "swinging" papillary muscle head with erratic movements in the ventricle, or a mobile mass attached to the chordae tendineae. The sensitivity of TTE and TEE for the diagnosis of PMR has been reported between 65 to 85% and 92 to 100%, respectively.…”

“…Conversely, the posterior papillary muscle is more sensitive to ischemia (91% of the cases in a series by Nappi et al) because of its single blood supply. 5…”