Left ventricular papillary muscle morphology and function in left ventricular hypertrophy and left ventricular dysfunction.

Background: This study was prospectively performed to evaluate the anatomy and contractile performance of LV papillary muscles (PM) in humans using transesophageal echocardiography (TEE), and to determine the relationship between PM anatomy and contractile function in normal left ventricle (LV), left ventricular hypertrophy (LVH) and systolic dysfunction.
Material and Methods: TEE examinations were prospectively performed in 153 patients. End-diastolic (ED) and end-systolic (ES) cross sectional areas of both PMs were obtained at the transgastric mid papillary short axis views. ED and ES lengths of PMs were obtained from the transgastric long axis views, and fractional systolic shortening (FS) was calculated. PM shape description was derived from the formula Area/L2. LV EF, wall thickness and mass were determined from transthoracic echocardiographic measurements.
Results: The % FS in patients with normal EF (>55%) was 21.1 +/- 9.1% for anterior PM (APM) and 17.1 +/- 6.2% for posterior PM (PPM). The values for hypertrophic LV were as follows; 25.2 +/- 8.1 (APM) and 15.8 +/- 5.6 (PPM), for dilated cardiomyopathy, 15.0 +/- 6.8 (APM) and 13.4 +/- 4.2 while values for non-dilated cardiomyopathy were 15.6 +/- 8.0 and 11.3 +/- 6.0 respectively. In dilated cardiomyopathy patients, both PM lengths were significantly longer (p<0.05) and thinner (p<0.05) than in patients with normal EF. In the hypertrophied LV, the PMs were thicker (p<0.05) and had larger cross sectional areas p<0.05.
Conclusions: TEE is a safe and useful method for detailed study of PM morphology and contractile performance in living humans with normal or impaired LV systolic function. Quantitative TEE data on PM geometry, size, and contractile function are presented here for the first time.