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Biomedical subjects

I G Maia

Publications and source records attributed to I G Maia.

At least 19 recordsLinked to original sources
PubMed1992

[Polymorphic ventricular tachycardia. Analysis of the onset of the episodes].

PURPOSE: To analyze the spontaneous onset of events for polymorphous ventricular tachycardia, to determine the importance of this parameter in the clinical and electrophysiologic context. METHODS: We evaluated 124 modes of onset of polymorphous ventricular tachycardias recorded by 24 hr of continuous ECG monitoring in 6 patients. Four patients were using quinidine and diuretics, and two patients only diuretics. We determined the two preceding cycle in milliseconds from the initiating events and also the induced cycle (cycles A, B and C). Careful analyses of T and U waves alternans and QT ou QTU intervals inside and outside the episodes of tachycardia. RESULTS: In 105 episodes (84%) the events were pause-dependent; in 12 episodes (10%) they occurred without pauses but after a ventricular fusion and in 7 episodes (6%) also without pauses but with sudden cycle (C) shortening (R on T phenomena). The pause-dependent episodes were only seen in patients using quinidine with the association of diuretics and non-pause related episodes were registered in patients using diuretics. All patients had prolonged QTU intervals outside the episodes. There were a linear correlation (r = 0.865) between the amplitude of the U waves of the cycles C and duration of cycles A and B, in pause-dependent episodes. CONCLUSION: The contribution of this study is that: the analyses of the spontaneous onset of polymorphous ventricular tachycardia can allow the differentiation of typic forms of torsades des de pointes (pause-dependent) and other atipic forms. The former type occurred probably as a result of EADs provoking triggered rhythms. The latter could be better explained as polymorphous ventricular tachycardia due to reentry mechanisms or enhanced automatic focus. Only the tipic forms should be acutely benefited with regularization of cardiac cycles with cardiac pacing.

Aged↗
PubMed1992

[R-R variability in acute anterior infarct after thrombolytic therapy].

PURPOSE: To analyse the effects of thrombolysis on the integrity of the autonomic nervous system, in patient with acute myocardial infarction (AMI) of the anterior wall, using the determination of the heart rate variability. METHODS: We prospectively evaluated the R-R variability of the 31 consecutive patients with anterior AMI submitted to coronary thrombolysis (25 males; mean age 59 +/- 14 years) from Holter tapes. An algorithm in a 286 computer program was used for heart rate variability (HRV). With this system, R-R variations during sinus rhythm and for a five consecutive minutes periods was determined. The results were expressed as the mean of the total determined periods; the standard deviation of the mean of all determined periods and the mean of the standard deviation. The reperfusion criteria was the early enzymatic rise of the CKMB activity levels (< or = 12 h) combined with a 50% or more reduction in the ST segment elevation within the first hour after thrombolytic therapy and the presence of an accelerated idioventricular rhythm at the same time. The reperfused group (group 1 = 16 patients) and non-reperfused group (group 2 = 15 patients) were compared in terms of R-R variability. RESULTS: Mean R-R: group 1 = 716 +/- 84 ms (540-820 ms); group 2 = 595 +/- 115 ms (390-870 ms)-p < 0.02. ms (34-92 ms); group 2 = 50 +/- 14 ms (23-77 ms)-p < 0.01. HRV 50 ms: group 1 = 2 patients; group 2 = 5 patients. Means SD of the R-R: group 1 = 44 +/- 14 ms (26-65 ms); group 2 = 39 +/- 17 ms (19-69 ms)-p: ns. CONCLUSION: Patients with anterior AMI and thrombolytic therapy demonstrate greater HRV; this finding suggested better integrity of the autonomic nervous system, with possible effects on prognosis.

Aged↗
PubMed1991

[Torsades de Pointes: analysis of 105 episodes].

PURPOSE: To analyze episodes of Torsades de Pointes (TP), in search of its electrocardiographic characteristics. PATIENTS AND METHODS: We analyzed 105 episodes of TP, in 4 patients using quinidine and diuretics, recorded by 24-hour Holter monitoring. The following parameters were studied; ventricular repolarization out of TP, rhythm disturbances before TP; EKG characteristics of the onset, the bouts and the end of the TP. RESULTS: Ventricular repolarization, out of the TP, was abnormal, with the presence of U-waves at the end of the T-waves, resulting in prolongation of the QT (QU) interval. The U-wave voltage was noted to be cycle-length dependent. Ventricular bigeminy preceded TP in 100 episodes (95%) and the mean interval between both parameters was 18 +/- 16 min. The onset of the TP episodes showed the "short/long/short cycle rule", hereby called "pre-pause cycle", "preparing cycle" and "trigger cycle" respectively. The rotatory QRS-T morphology around the baseline, was seen in 75% of episodes, at the beginning or throughout the bout. Monomorphic ventricular tachycardia pattern was seen in the other 25% of episodes. Termination of bouts was sudden in all cases, and persistent ventricular bigeminy led to another bout in 90 episodes (85%). CONCLUSION: In TP patients, there is enlargement of QT intervals mostly due to U-waves appearance. The U-waves seen in these cases, probably have an important role in the genesis of TP and are probably related to ventricular after-potentials (triggered activity). Ventricular bigeminy is a premonitory sign of TP in patients using class 1A antiarrhythmic drugs. Persistent ventricular bigeminy post-TP episodes is a strong indicator of another bout of TP. The onset of TP is more important than its morphology for the correct diagnosis of this arrhythmia.

Aged↗
PubMed1991

[Arrhythmogenic right ventricular dysplasia].

PURPOSE: To evaluate the clinical findings and complementary investigation to support the diagnosis of arrhythmogenic right ventricular dysplasia. METHODS: Six males with a mean age of 40 years old with episodes of sustained ventricular tachycardia with left bundle branch block pattern. All patients were submitted to a clinical investigation, EKG X rays and echocardiograms. In five patients an electrophysiologic study was performed. All patients were treated with anti-arrhythmic drugs. RESULTS: Palpitation was the most common complaint. T-wave inversion in leads V1-V3 was present in 4 patients. An epsilon wave was noted in 2 patients. The chest X ray was abnormal in only 1 patient. All patients had an abnormal echocardiogram, with consisted in the dilatation of the outflow tract of the RV and hypocontractility. In 2 patients aneurysm of the basal RV free wall below tricuspid valve were detected. Ventricular post-excitation waves were present in 4 patients. After a mean follow-up of 37 months, 5 patients were asymptomatic with anti-arrhythmic drugs and one in therapeutic adjustment. CONCLUSION: In patients with ventricular tachycardia with left bundle branch block pattern, the diagnosis of arrhythmogenic right ventricular dysplasia was substantiated by echocardiographic data and electrocardiographic findings such a T-wave inversion during sinus rhythm and ventricular post-excitation waves. The results obtained with anti-arrhythmic drugs in our study group, suggest that drug therapy should be the first and best approach to treat patients with this type of pathology.

Adult↗
PubMed1991

[Cardiac memory in patients with permanent artificial pacemakers].

PURPOSE: To correlate the direction of QRS complex of paced beats and postpacing T wave, in patients with artificial pacemaker. METHODS: Thirty five patients with spontaneous rhythm obtained by chest wall stimulation or by programmability of the automatic interval. It was correlated in all patients, the direction forces of QRS complexes of paced beats and postpacing T waves in all 12 ECG leads. It was considered as a cardiac memory phenomenon when QRS complexes of paced beats and postpacing T waves had the same polarity. The phenomenon was correlated with the 12 ECG leads and with specific variables like spontaneous rhythm, QRS complex duration, type and modality of artificial stimulation and chronicity of the implant. RESULTS: The artificial QRS complexes and spontaneous T waves had the same direction in 5 or more leads of the frontal plane in 77% of the patients and in 50% of the patients in the horizontal plane. In patients with supraventricular command, this correlation was found in 82% of the patients and in 50% of the patients with idioventricular rhythm. Regardless of the type of spontaneous command, the phenomenon was better observed with normal intraventricular conduction. It was not found correlation between type, modality of stimulation and chronicity of the implant and cardiac memory. It was better observed in aVF, D2, D3 and V3, V4. CONCLUSION: The phenomenon of cardiac memory in patients with artificial pacemaker is very frequent. The most important factor to develop the phenomenon seem to be a normal pattern of ventricular activation.

Adult↗
PubMed1986

Atrioventricular block in acute inferior wall myocardial infarction: harbinger of associated obstruction of the left anterior descending coronary artery.

In a prospective study 51 consecutive patients who survived the acute phase of inferior wall myocardial infarction underwent coronary arteriography. Eleven patients developed some degree of atrioventricular (AV) block in the acute phase of infarction that disappeared within a few days and was considered by electrocardiographic analysis to be located in the AV node. Patients with AV block during acute myocardial infarction had a significantly higher prevalence of left anterior descending coronary artery obstruction (91 versus 55%, p less than 0.05) than did patients without AV block and the obstruction preceded the exit of the first septal perforator branch in 73% of cases with heart block and in 30% of cases without block (p less than 0.01). The sensitivity, specificity and predictive values were 31, 95 and 91%, respectively, for the existence of left anterior descending coronary artery obstruction when AV block occurred during acute inferior myocardial infarction, and 40, 90 and 73%, respectively, for the occurrence of the coronary artery obstruction before the exit of the first septal perforator branch. Patients with inferior myocardial infarction and left anterior descending coronary artery obstruction have a sixfold greater chance of developing heart block in the acute phase of infarction than do patients with inferior infarction without such obstruction (p less than 0.05). These findings also support the observations that the proximal AV conduction system usually has a dual arterial blood supply from both the right and left anterior descending coronary arteries, and may explain the transient behavior of heart block and lack of necrosis of the AV node seen in these patients.

Angiography↗