Mario G. Lopes

Arrhythmias in patients with mitral valve prolapse.

Resting ECGs, exercise treadmill tests and 24-hour ambulatory ECGs were recorded and analyzed in 24 unselected patients with mitral valve prolapse. Arrhythmias were frequent. There were three distinct groups of patients, defined on the basis of total number of premature ventricular contractions (PVCs) during the 24 hours: there were no PVCs in 25%, infrequent PVCs in 25%, and frequent PVCs in 50%. Complex ventricular arrhythmias, including ventricular tachycardia in five patients, were found almost exclusively in the group with frequent PVCs. Fifteen of the 24 patients demonstrated atrial premature contractions (APCs) during the 24 hours. Complex atrial arrhythmias were found among patients with infrequent, as well as those with frequent, APCs. Supraventricular tachycardia was detected in seven of these patients. The incidence of PVCs decreased during sleep in 58% of the patients, increased in 17%, and showed no change in 25%. The incidence of APCs decreased during sleep in 67% of the patients and showed no change during sleep in 33%. A poor correlation was found between symptoms recorded in patient diaries and changes noted on 24-hour ECG recordings. The peak PVCs/15 min and peak APCs/15 min during a 24-hour period of monitoring was found to be an excellent guide to the total number of PVCs and APCs occurring during that period. This permits an accurate prediction of the total number of PVCs in 24 hours after performing an exact PVC count on only 15 minutes of ECG data. Finally, the 24-hour ambulatory ECG was more sensitive than the treadmill test and both were superior to the 12-lead ECG for detecting arrhythmias in these patients.

Propranolol for patients with mitral valve prolapse

This study evaluates propranolols effect on symptoms, arrhythmias, and exercise tolerance in 16 patients with mitral valve prolapse. Three patients (19 per cent) experienced symptomatic deterioration with propranolol therapy, seven (44 per cent) were unchanged, and six (37 per cent) noted an over-all symptomatic improvement, primarily due to a reduction in palpitation. Symptomatic improvement continues in these six patients an average of 12.5 months after beginning propranolol therapy. Treatment with propranolol alleviated chest pain in only two of eight patients and it did not improve the ability to perform treadmill exercise. Fatigue did not improve, and in three patients appeared for the first time during propranolol therapy. Premature ventricular contractions were reduced by at least 75 per cent in five of nin patients (56 per cent), and paroxysmal ventricular tachycardia was eliminated in three of four patients. We conclude that propranolol is not uniformly effective in patients with mitral vale prolapse. A trial of propranolol may be instituted fro patients with mitral valve prolapse who have severe symptoms and/or arrhythmias, but the drug should only be continued in those who demonstrate clinical and/or antiarrhythmic response.

Life-threatening arrhythmias in the mitral valve prolapse syndrome.

This study describes seven patients with the mitral valve prolapse or click-murmur syndrome who have survived one or more episodes of life-threatening ventricular arrhythmias. These arrhythmias include cardiac arrest due to ventricular fibrillation, recurrent ventricular tachycardia causing syncope or sustained ventricular tachycardia requiring electroversion. These patients were seen over a two-year period in a single medical center. Five of the seven had repolarization abnormalities in the resting electrocardiogram. Premature ventricular contractions were present in the routine resting electrocardiograms of six of the seven patients and were frequent during treadmill testing and ambulatory electrocardiographic monitoring in all six tested. There were electrolyte abnormalities or changes in medications known to affect myocardial repolarization during the week before the episode in three of the four patients with cardiac arrest. The diagnosis of mitral valve prolapse click-murmur syndrome was made prior to the episode of life-threatening arrhythmia in only two of the seven patients. Varying forms of antiarrhythmic therapy were given to these patients during follow-up periods of five to 26 months. Although the incidence of fatal arrhythmias in the mitral prolapse syndrome is probably small, we suggest that such arrhythmias may not be extremely rare, particularly among those patients who have repolarization abnormalities in the resting electrocardiogram and frequent premature beats. Patients with unexplained ventricular arrhythmias should be screened for mitral valve prolapse.

Analysis of left ventricular function in response to afterload changes in patients with mitral stenosis.

In order to assess left ventricular function in patients with rheumatic mitral stenosis, left ventricular function curves (plotting stroke work index vs left ventricular end-diastolic pressure) were constructed using angiotensin to augment, and nitroprusside to reduce, afterload. Hemodynamic responses to these alterations in afterload were measured. Resting ejection fractions and qualitative assessment of left ventricular angiographic contraction abnormalities were also determined. Changes in left ventricular end-diastolic pressure following afterload interventions could be linearly related to changes in mean aortic pressure, but mitral valve gradients were unaffected. Afterload reduction with nitroprusside did not augment cardiac output. Afterload elevation with angiotensin significantly depressed both cardiac output and calculated mitral valve areas. Patients with normal resting ejection fractions evidenced normal ventricular function curves and those with depressed ejection fractions showed flat or declining function curves. Contraction abnormalities, generally in the posterobasal area, correlated well with abnormal left ventricular function curves.

Diagnosis and quantification of arrhythmias in ambulatory patients using an improved R-R interval plotting system☆

An improved technique for identification, diagnosis and quantification of arrhythmias during rest or ambulatory electrocardiographic recording is described. With simultaneous plotting of the R-R interval and the QRS duration and QRS vector measurement of each beat versus time, all periods of arrhythmias or abnormal complexes can be identified and characterized. Analog electrocardiographic samplings are used to confirm the diagnosis of the arrhythmia and to exclude artifact. The availability of a permanent record for the characterization of each QRS complex enables the physician to check the technicians analysis of the recording and to relate all events to the patients heart rate and clinical symptoms. This technique also provides data for quantification of ventricular arrhythmias.