Increased plasma catecholamine levels in patients with symptomatic mitral valve prolapse

Total plasma catecholamine levels, plasma norepinephrine levels, heart rate, and systolic and diastolic pressures were measured in 15 symptomatic patients with mitral valve prolapse and in 19 normal subjects in supine baseline conditions and in a standing position. In the 15 symptomatic patients, total plasma catecholamine levels and plasma norepinephrine levels were significantly elevated in both positions, and heart rate was lower than in normal subjects in the supine position but returned to normal in the upright position. Thus, symptomatic patients with mitral valve prolapse demonstrate increased resting sympathetic tone. In addition, the associated supine bradycardia suggested that increased vagal tone might also be present at rest. These observations support the hypothesis of a dual autonomic dysfunction in these patients and could account for some of the clinical manifestations of the mitral valve prolapse syndrome. © 1982

QT interval prolongation and increased plasma catecholamine levels in patients with mitral valve prolapse

The heart rate corrected QT interval (QTc) and plasma catecholamine (CA) and norepinephrine (NE) levels were measured in 15 symptomatic patients with idiopathic mitral valve prolapse (MVP) and in 19 control subjects. MVP patients showed longer mean QTc and were divided into two groups: group A normal QTc (> 440 msec) and group B prolonged QTc (< 440 msec). In supine resting conditions CA levels were as follows: group A 0.420 ± 0.035 ng/ml and group B 0.619 ± 0.104 ng/ml (p < 0.05); both were greater than control values (0.348 ± 0.017 ng/ml, p < 0.005). NE levels were as follows: group A 0.350 ± 0.031 ng/ml and group B 0.376 ± 0.052 ng/ml (NS); both were greater than control values (0.242 ± 0.025 ng/ml, (p < 0.05). When a standing position was assumed, CA and NE levels increased significantly in all groups but this was most marked in group B as compared to control levels (CA: 1.039 ± 0.123 ng/ml versus 0.625 ± 0.037 ng/ml; NE: 0.737 ± 0.076 ng/ml versus 0.504 ± 0.031 ng/ml) (p < 0.001 and p < 0.05, respectively). Thus the longest QTc was observed in patients with MVP who had the highest levels of CA and NE, in both supine and standing positions. These data may account, in part, for the occurrence of severe ventricular arrhythmias in some patients with MVP and may offer a rationale for adrenergic blockade in that subset of patients with MVP and markedly prolonged QTc. © 1983