Clinical significance of the V wave in the main pulmonary artery.

Among 68 patients with mitral insufficiency who had right and left cardiac catheterization and left ventriculography, 6 had retrograde transmission of the left atrial V wave into the main pulmonary artery. All of these patients had mitral insufficiency of acute onset. The remaining 62 patients had chronic mitral insufficiency that was considered severe in 17. Pulmonary vascular resistance was lower in the group with acute insufficiency (mean 139 dynes sec cm-5) than in the group with chronic severe insufficiency (mean 631 dynes cm-5) (P less than 0.005). Nondistensibility of the left atrium and low pulmonary vascular resistance were the two factors favoring retrograde transmission of V waves. Because both factors are present in acute mitral regurgitation, this finding is helpful in differentiating patients with acute mitral insufficiency.