Hemodynamic Studies in Patients with 2M and 3M Starr-Edwards Prostheses: Evidence of Obstruction to Left Atrial Emptying

The hemodynamic findings in 28 patients with small (2M uncovered, 2M and 3M covered) Starr-Edwards mitral prostheses are compared with the findings in 12 patients with larger (3M and 4M uncovered) prostheses. Although most patients with the smaller prostheses evidenced both clinical and hemodynamic improvement after operation, the majority continued to have a significant left atrial-left ventricular pressure gradient and an elevated left atrial pressure at rest. During exercise the gradient increased, and left atrial pressure was abnormally elevated in each patient. The hemodynamic findings were decidedly less satisfactory in patients with smaller prostheses than in patients in whom it had been possible to insert larger prostheses. It is concluded that the major site of obstruction to left atrial emptying in patients with smaller prostheses is the small primary orifice of the prosthesis present at the time of insertion. Further narrowing of the primary or secondary orifices by thrombus and/or tissue ingrowth probably contributes to the obstruction in some patients.