Mitral valve prolapse syndrome: The effect of adrenergic stimulation

Previous studies demonstrating increased adrenergic tone in symptomatic patients with mitral valve prolapse prompted a study of the response of symptomatic patients with mitral valve prolapse to adrenergic stimulation. Sixteen such patients had plasma catecholamines and 24 hour urinary epinephrine plus norepinephrine values that were greater than those of control subjects (473.3 ± 92.8 pg/ml versus 292 ± 15 and 44.7 ± 2.3 μg/g creatinine versus 29.8 ± 2.3; p < 0.01 and < 0.001, respectively). Twenty-four hour urinary sodium was lower in the patient group than in the control group (75 ± 7.4 versus 141 ±11 mEq; p < 0.01), with an inverse relation between urinary sodium and norephinephrine in the patient group (r = - 0.78) but not in the control group.Isoproterenol infusions, 0.5, 1.0 and 2.0 μg/min for 6 minutes, produced a dose-related, greater increase in heart rate in the mitral valve prolapse group than in the control group (16.1 ± 2.3 versus 10 ± 2; 31.8 ± 3.5 versus 19.6 ± 3; 48 ± 4.1 versus 27 ± 3; p< 0.01 with 0.5, 1.0 and 2.0 μg, respectively). The greater increase in heart rate resulted in a significantly shorter diastolic time in the patient group than in the control group (26.4 ± 2 s/min versus 30.6 ± 2; 27 ± 1.5 versus 30.6 ± 2; 26.6 ± 2 versus 30.9 ± 2; p < 0.01 with 0.5, 1.0 and 2.0 μg, respectively). The QT interval was 25 ms shorter than electromechanical systole (QS2) in the normal group and 26.5 ms shorter than QS2in the mitral valve prolapse group at rest; during isoproterenol infusion QT-QS2values were different in the mitral valve prolapse and control groups (3.3 ± 3 versus -7.0 ± 3; 31.9 ± 2.8 versus 10 ± 4; 52 ± 9.2 versus 29 ± 8; p < 0.01 with 0.5, 1.0 and 2.0 μg/min, respectively). Isoproterenol infusion also reproduced symptoms on a dose-related basis in 14 patients with mitral valve prolapse but not in control subjects (excluding palpitation).Symptomatic patients with mitral valve prolapse and high rest values of catecholamines were hypersensitive to isoproterenol infusion, suggesting that some of the symptoms are catecholamine-related or mediated

The marfan syndrome: Abnormal aortic elastic properties

Aortic distensibility and aortic stiffness index were measured at the ascending aorta (3 cm above the aortic valve) and the mid-portion of the abdominal aorta from the changes in echocardiographic diameters and pulse pressure in 14 patients with the Marfan syndrome and 15 age- and gender-matched normal control subjects. The following formulas were used: 1) Aortic distensibility = 2(Changes in aortic diameter)/(Diastolic aortic diameter) (Pulse pressure); and 2) Aortic stiffness index = ln(Systolic blood pressure)/(Diastolic blood pressure)(Changes in aortic diameter)/Diastolic aortic diameter. Pulse wave velocity was also measured.Compared with normal subjects, patients with the Marfan syndrome had decreased aortic distensibility in the ascending and the abdominal aorta (2.9 ± 1.3 vs. 5.6 ± 1.4 cm2 dynes-1, p < 0.001 and 4.5 ± 2.1, vs. 7.7 ± 2.5, cm2 dynes-1, p < 0.001, respectively) and had an increased aortic stiffness index in the ascending and the abdominal aorta (10.9 ± 5.6 vs. 5.9 ± 2.2, p < 0.005 and 7.1 ± 3.1 vs. 3.9 ± 1.2, p < 0.005, respectively). Aortic diameters in the ascending aorta were larger in these patients than in normal subjects, but those in the abdominal aorta were similar in the two groups. Linear correlations for both aortic distensibility and stiffness index were found between the ascending and the abdominal aorta (r = 0.85 and 0.71, respectively). Pulse wave velocity was more rapid in the patients than in the normal subjects (11.6 ± 2.5 vs. 9.5 ± 1.4 m/s, respectively, p < 0.01).Thus, aortic elastic properties are abnormal in patients with the Marfan syndrome irrespective of the aortic diameter, which suggests an intrinsic abnormality of the aortic arterial wall

Atrial septal defect: Attenuation of respiratory variation in systolic and diastolic time intervals

The effects of pathologic states on right and left ventricular function have been studied extensively. However, there have been few studies on the interrelations between right and left ventricular function in normal human subjects and in patients with disease. Respiratory effects on ventricular interrelations reflected by diastolic time, right or left ventricular systolic time and ventricular performance (pre-ejection period/ejection time ratio) were studied in 12 normal subjects and 15 patients with a normal pressure-large shunt atrial septal defect. Simultaneous pulmonary artery (intracardiac manometer recordings) and left ventricular external recordings were performed in both groups.Left ventricular diastolic time increased with inspiration in the normal subjects and decreased in the patients with atrial septal defect (12.6 ± 2.39 [1 SE] versus −13.4 ± 3.48 ms, p < 0.001). Left ventricular systolic time and ejection time decreased with inspiration in the normal group and remained unchanged in the patient group (−7.6 ± 0.95 versus −0.9 ± 0.77 ms, p < 0.001 and −10.4 ± 1.09 versus −1.7 ± 0.80 ms, p < 0.001, respectively). Left ventricular pre-ejection period/ejection time ratio increased with inspiration in the normal subjects and remained unchanged in the patients with atrial septal defect (0.03 ± 0.008 versus 0 ± 0.01, p < 0.01). Right ventricular diastolic time decreased with inspiration in normal and patient groups (− 8.8 ± 1.6 versus −17 ± 3.87 ms). Changes with inspiration in right ventricular systolic time, ejection time, pre-ejection period and pre-ejection period/ejection time were significantly greater in normal subjects than in patients with atrial septal defect (13.8 ± 0.89 versus 5.7 ± 1.26 ms, p < 0.001; 32 ± 2.89 versus 10.3 ± 1.57 ms, p < 0.001; −18.2 ± 2.93 versus −4.6 ± 1.26 ms, p < 0.01 and −0.06 ± 0.01 versus −0.02 ± 0.001, p < 0.001, respectively).Thus, all respiratory left ventricular-right ventricular changes were significantly smaller in patients with atrial septal defect than in normal subjects. It is concluded that atrial septal defect markedly attenuates the respiratory changes of right and left ventricular time relations, which in normal human subjects are modulated by the intact interatrial septum

Postural exercise abnormalities in symptomatic patients with mitral valve prolapse

AbstractThe hemodynamics of the supine and upright exercise response in 16 symptomatic women with mitral valve prolapse (Group I) was compared with that in 8 asymptomatic normal control women (Group II). All subjects had supine and upright echocardiography and phonocardiography at rest and none demonstrated mitral regurgitation. All participants then underwent same day graded bicycle exercise, with simultaneous radionuclide angiography in both the upright and the supine posture. Catecholamines were measured, and a variety of volumetric and hemodynamic data were obtained.Group I (patients with mitral valve prolapse) demonstrated a reduced exercise tolerance, especially during upright exercise, as measured by both total exercise duration and maximal work load achieved. Mean total catecholamine measurements were similar between the two study groups at comparable mean heart rate, mean blood pressure and mean rate-pressure (double) product. No difference was observed in the ratio of right to left ventricular stroke counts at rest or during exercise regardless of posture, suggesting that exercise-induced mitral regurgitation did not occur.A difference was noted, however, in left ventricular end-diastolic volume index. At rest, Group I patients exhibited a 42% decrease in this index when sitting upright, and this difference from supine values persisted at submaximal (300 kpm/min) and peak work loads (34 and 29% difference, respectively). This contrasted with the control subjects whose upright end-diastolic volumes at rest, at 300 kpm/min and at peak exercise were reduced 21, 10 and 3%, respectively, compared with supine values. Cardiac index measurements reflected the reduced left ventricular end-diastolic volume observed. Other measurements, including ejection fraction, left ventricular end-systolic volume index and peak systolic pressure/end-systolic volume ratio, were similar between the two groups at each posture and level of exercise. The percent stroke volume ejected during each third of systolic ejection was also not remarkably different between the groups.In summary, as compared with control subjects, patients with mitral valve prolapse exhibit an exaggerated reduction in left ventricular end-diastolic volume throughout upright exercise. The associated redaction in cardiac output at each level of exercise may contribute to the reduction in exercise tolerance observed in this symptomatic patient subset

Mitral Valve Prolapse: Cardiac Arrest With Long-Term Survival

Cardiac arrest has been reported in patients with mitral valve prolapse; however, clinical characteristics and survival information are limited since most of the cases reported include autopsy data. Nine patients (2 male, 7 female) with mitral valve prolapse were identified who had cardiac arrest; ventricular fibrillation was documented in 8 patients; resuscitation was unsuccessful in 2. Eight had a history of palpitations (months to 15 years duration) and ventricular arrhythmias, 3 had a history (5-15 years) of recurrent syncope, and 1 was totally asymptomatic. Cardiac catheterization-angiographic studies in 8 patients demonstrated normal coronary artery anatomy and mitral valve prolapse. All 9 patients had auscultatory and echocardiographic evidence of mitral valve prolapse. Seven survivors (6 still alive) were followed from 3 to 14 years after cardiac arrest. A subset of patients with mitral valve prolapse and cardiac arrest is described in whom past medical history is compatible with cardiac arrhythmias or syncope, and whose long-term prognosis appears better than patients with other causes of cardiac arrest