Abstract 3645: Dynamic CMR Cardiac Anatomy: The ’Cypress Tree’ Papillary Muscle Root
Introduction The understanding of gross cardiac anatomy has been relatively stable over the last 80 yrs, reliant on well-established autopsy findings. The advent of dynamic imaging by cardiac MRI (CMR) and CT provides a window to view anatomic features in vivo, providing insights typically masked at autopsy due to death.
Hypothesis We hypothesize that CMR with its high spatial and temporal resolution allows detection of anatomic features not previously appreciated at autopsy.
Methods Four hundred and one (401) pts underwent CMR (GE, 1.5T) examinations with 255 retrospectively and 146 prospectively examined to determine anatomic features of the LV papillary muscles (PM). Specifically, the basal origins of the PM were defined.
Results The insertion of the PM was seen in 401/401 pts (100%). In 392 out of 401pts (97.8%), the appearance of the PM was not a uniform appearing muscle arising from the inner face of the LV endocardium, but was a finger-like series of long, root-like slender trabeculae carnae traversing >1cm before inserting into the main body of PM, challenging our previous understanding of PM anatomy (see Fig⇓).
Conclusion The capabilities of CMR to view cardiac features in vivo non-invasively affords a useful tool to study living cardiac anatomy. Unlike the widely accepted belief that papillary muscles uniformly arise from the LV floor, they resolve into a ’cypress tree’ root-like structure with multiple thin projections before coalescing into a thick muscle head. Such observations have far reaching clinical implications in areas such as mitral regurgitation, post MI remodeling and electrical transmission of the His-Purkinje system while challenging our classic teachings.