Biomedical subjects
M G Lopes
Publications and source records attributed to M G Lopes.
[Role of echocardiography in cardiac insufficiency].
Several clinical cases are presented showing that Echocardiography (M-mode, 2D and Doppler) may give us a complete picture of the heart anatomy and the physiopathology associated with heart failure, as well as the functional status of the left ventricle. With this useful information (presence, location and degree of the abnormality) that can be obtained at bedside in a non-invasive way, the cardiologist may take, without delay, the most correct therapeutic choice (surgical and/or medical). Echocardiography should be used as a first line diagnostic test (after ECG and Chest X Ray) in all patients presenting with heart failure.
Intraventricular conduction defects associated with hypertrophic myocardiopathy-an echocardiographic and vectorcardiographic study.
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Left median hemiblock-a chimera?
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Propranolol for patients with mitral valve prolapse.
This study evaluates propranolol's 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.
Long-term prognosis of the left anterior hemiblock.
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Left posterior hemiblock. A new cause of mitral valve prolapse.
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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.
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 technician's analysis of the recording and to relate all events to the patient's heart rate and clinical symptoms. This technique also provides data for quantification of ventricular arrhythmias.
Aneurysms of the coronary arteries in the adult. Clincial and angiographic features.
One thousand coronary arteriograms were reviewed to determine the incidence, clinical presentation and angiographic features of aneurysms of the coronary artery (ACA) in adults with angina. Criteria for the angiographic diagnosis are described and the angiographic aspects are emphasized. The incidence of ACA was 1.1%. Saccular and fusiform aneurysms were seen. Single aneurysms were present in 7 patients. One patient had an abdominal aneurysm. Five patients underwent surgery; two had postoperative selective coronary angiography one year later and all five underwent follow-up left ventricular angiography. The most likely etiology of the aneurysms in this series is atherosclerosis.
Dose response effectiveness of propranolol for the treatment of angina pectoris.
Seventeen patients received placebo medication during a 12-week run-in period, followed by four double-blind study periods of six weeks each, during which time placebo, 80 mg, 160 mg and 320 mg propranolol dosages were administered. Examination of the frequency of angina episodes and nonprophylactic nitroglycerin consumption revealed significant beneficial clinical responses for both the 160 and 320 mg dosages. Exercise testing also demonstrated increased exercise tolerance (320 mg dose) with a shift of the exercise end point from pain to fatigue in seven of 17 patients. The interrelationships between propranolol daily dosage, clinical response assessed by percent reduction in anginal episodes, beta-adrenergic blockade measured by percent reduction in exercise heart rate and serum levels were examined. In general, serum levels of 30 ng/ml, when drawn 90 to 180 minutes following the last oral dose, were required to achieve a 25% or greater reduction in angina frequency. Serum levels above 30 ng/ml were similarly correlated with a 20% or greater reduction in exercise heart rate at equivalent levels of exercise. Detailed examination of different patterns of clinical response with respect to beta-blockade, serum levels and oral doses are presented.
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%, 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 ACPs 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 ACPs/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 sensitive than the treadmill test and both were superior to the 12-lead ECG for detecting arrhythmias in these patients.
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.
Comparison of 24 versus 12 hours of ambulatory ECG monitoring.
In order to assess the additional information obtained from 24 hours compared to 12 hours of ambulatory ECG (electrocardiogram) recording, we analyzed 72 ambulatory ECG monitoring tapes in which arrhythmias were present. In all cases the second 12 hours included the entire period of sleep. Only 38 of 233 (16 percent) episodes of arrhythmias, frequent premature ventricular contractions (PVC's), two or more PVC's in a row, multiform PVC's, ventricular bigeminy, trigeminy, premature atrial contractions (PAC's), and supraventricular tachyarrhythmias occurred for the first time in the second 12-hour period. New ventricular arrhythmias were detected during the second 12-hour period in 13 percent of the arrhythmic episodes. Although sleep resulted in a marked decrease in PVC frequency in 63 percent of 30 recordings, with frequent PVC's while awake, 8 percent had a significant increase during sleep. In contrast, short runs of supraventricular tachyarrhythmias occurred during the second 12 hours in 48 percent of cases, 66 percent of these while asleep. These data suggest that a 24-hour ambulatory ECG tape recording be utilized initially to characterize the occurrence and frquency of the patients' ambulatory arrhythmias during awake and sleep periods. Thereafter, additional ECG recordings for monitoring antiarrhythmic drug therapy can be accomplished with a 12-hour recording in more than 80 percent of patients
Echocardiography in cardiac diagnosis.
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Ventricular arrhythmias during unstable angina pectoris.
In order to study the occurrence and frequency of ischemia-induced ventricular arrhythmias, we analyzed 105 episodes of spontaneous angina pectoris occurring at rest in 28 hospitalized patients with unstable angina pectoris and proved coronary artery disease. Of 24 patients with serious ventricular arrhythmias during pain, 17 (57%) were arrhythmia-free during monitoring. In the other four patients, 17 of 29 (59%) pain episodes were associated with serious ventricular arrhythmias, and three of these four had serious ventricular arrhythmias during pain-free periods. Each patient tended to manifest the same type of arrhythmia during repeat episodes of pain. It appears that continuous electrocardiogram (ECG) monitoring is important during the initial hospitalization of the patient with unstable angina. The presence of ventricular arrhythmias during pain-free periods indicates a high risk for serious ventricular arrhythmias during episodes of spontaneous pain. These patients should be considered for continued ECG monitoring and antiarrhythmic therapy.
Prognosis in coronary care unit noninfarction cases.
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[Mitral valve prolapse].
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