Ivan G Maia

Telemetry of arterial flow in man with a Doppler ultrasonic flowmeter

Abstract 1. 1. Transcutaneous measurements of brachial artery flow velocity with the Doppler ultrasonic flowmeter were made in 82 subjects, of whom 24 were normal and 58 had heart disease. 2. 2. Aortic stenosis was associated with low peak flow velocity, prolonged ascending limb of the primary wave and decreased retrograde wave. Aortic insufficiency was recognized by the presence of a large secondary wave thought to represent retrograde flow. Subaortic stenosis altered the flow waveform in a characteristic manner. 3. 3. The technic was also found to be useful in the study of cardiac arrhythmias, Valsalva maneuvers and in the study of drugs with primary effect on the peripheral circulation. 4. 4. Although more experience is needed with its use in man, it appears that it may become a useful technic for monitoring patients in intensive care units.

Electrical behavior of T-wave polarity alternans in patients with congenital long QT syndrome.

OBJECTIVES This study was designed to evaluate the incidence and characteristics of onset of T-wave polarity alternans (TWPA) in patients with long QT syndrome. BACKGROUND The T-wave alternans is a phenomenon that consists of beat-to-beat variability in the amplitude, morphology, and sometimes polarity of the T-wave, and it may trigger life-threatening arrhythmias. METHODS The 24-h Holter recordings of 11 patients with congenital long QT syndrome were studied. Episodes of TWPA with 10 or more consecutive cycles were selected and analyzed as follows: 1) mean cycle length (MCL) and QTc interval duration (QTcI) of the episodes of TWPA and the 10 cycles preceding and succeeding the TWPA; 2) MCL and QTcI of the third, second, and first minute before onset (Mn_3, Mn_2, Mn_1); 3) MCL and QTcI from the tenth to the first cycle immediately preceding the onset of TWPA (R_10 to R_1); 4) MCL and QTcI from the first to the fourteenth cycle during alternans (R0 to R14); 5) MCL and QTcI from the first to the tenth cycle immediately succeeding TWPA (R+1 to R+10); 6) linear correlation (Lnc) between QT interval and cycle length (CL) (LncQT/CL) during alternans and for the 10 preceding cycles; 7) Lnc between the first three alternans cycles and episode duration (Lnc 3CL/EpD); and 8) difference between the longest and shortest QTc interval. We also selected episodes consisting of four or more consecutive cycles in order to analyze daily rhythms of the phenomenon. RESULTS The TWPA was observed in 5 (45%) out of the 11 patients studied. The alternans process is initiated by a sudden shortening of the first alternans cycle without previous heart rate changes and ends at the moment when prolongation of the cycle tends to occur. LncQT/ CL-alternans: r = 0.38 +/- 0.2 (p = 0.20); without alternans: r = 0.81 +/- 0.06 (p = 0.01). Lnc 3CL/EpD: r = 0.002 (p = 0.992). The QTc difference during alternans: 312.0 +/- 52.1 ms; without alternans: 86.0 +/- 36.4 ms (p = 0.001). Daily rhythm: 71% of the episodes occurred between 8 AM and 8 PM, with higher incidence during the morning. CONCLUSIONS The TWPA was dependent on the cardiac CL; there was loss of the LncQT/CL and an increase in the QT interval variability. Like other biological variables, T-wave polarity alternans has a higher density during the morning.

Signal-averaged P wave in patients with wolff-parkinson-white syndrome after successful radiofrequency catheter ablation

OBJECTIVES We attempted to establish a relation between the atrial conduction time assessed by the signal-averaged P wave electrocardiogram and episodes of paroxysmal atrial fibrillation in patients with the Wolff-Parkinson-White syndrome. BACKGROUND The incidence of paroxysmal atrial fibrillation is higher in patients with the Wolff-Parkinson-White syndrome than in normal persons. However, the role of intraatrial conduction delay in precipitating the disorganization of atrial rhythm is not completely understood. METHODS The total duration of the signal-averaged P wave and the P wave in standard lead II was evaluated after successful radiofrequency catheter ablation in 28 patients with the Wolff-Parkinson-White syndrome. The data obtained from 17 patients (61%) with a documented history of prior paroxysmal atrial fibrillation (group I) were compared with those obtained from 11 patients (39%) without a history of atrial fibrillation (group 2). Both groups were further compared with a normal control population. RESULTS The mean +/- SD signal-averaged P wave duration in group 1 was 141.94 +/- 9.47 ms (range 130.0 to 171.0). Fourteen patients (82%) in this group showed a P wave duration > 135.0 ms. In group 2, the signal-averaged P wave duration was 126.64 +/- 8.72 ms (range 111.0 to 136.0). Only one patient in this group (9%) showed a P wave duration > 135.0 ms (p < 0.000, group 1 vs. group 2). The signal-averaged P wave duration in the control group was 124.46 +/- 4.49 ms (range 115.0 to 129.5; p < 0.000, group 1 vs. the control group; p < 0.454, group 2 vs. the control group). The P wave duration in lead II was 92.06 +/- 8.85 ms in group 1 and 92.27 +/- 7.86 ms in group 2 (p < 0.949). Using a cutoff value of < 135.0 ms for a normal signal-averaged P wave duration, the method had a sensitivity and specificity and positive and negative predictive values of 82%, 91%, 93% and 77%, respectively, for identifying patients with clinical paroxysmal atrial fibrillation. CONCLUSIONS In the current study, the signal-averaged P wave showed a prolonged intraatrial conduction time in patients with the Wolff-Parkinson-White syndrome and paroxysmal atrial fibrillation. These patients can be differentiated from those with the pre-excitation syndrome without clinical atrial fibrillation as well as from normal subjects. The prolonged intraatrial conduction time may serve as an atrial substratum for development and maintenance of the fibrillatory state.

Arrhythmogenic cardiomyopathy of the right ventricle. Predictive value of QT interval dispersion to assess arrhythmogenic risk and sudden death

OBJECTIVE To determine in arrhythmogenic right ventricular cardiomyopathy the value of QT interval dispersion for identifying the induction of sustained ventricular tachycardia in the electrophysiological study or the risk of sudden cardiac death. METHODS We assessed QT interval dispersion in the 12-lead electrocardiogram of 26 patients with arrhythmogenic right ventricular cardiomyopathy. We analyzed its association with sustained ventricular tachycardia and sudden cardiac death, and in 16 controls similar in age and sex. RESULTS (mean +/- SD). QT interval dispersion: patients = 53.8+/-14.1 ms; control group = 35.0+/-10.6 ms, p = 0.001. Patients with induction of ventricular tachycardia: 52.5+/-13.8 ms; without induction of ventricular tachycardia: 57.5+/-12.8 ms, p =0.420. In a mean follow-up period of 41+/-11 months, five sudden cardiac deaths occurred. QT interval dispersion in this group was 62.0+/-17.8, and in the others it was 51.9+/-12.8 ms, p = 0.852. Using a cutoff > or =60 ms to define an increase in the degree of the QT interval dispersion, we were able to identify patients at risk of sudden cardiac death with a sensitivity of 60%, a specificity of 57%, and positive and negative predictive values of 25% and 85%, respectively. CONCLUSION Patients with arrhythmogenic right ventricular cardiomyopathy have a significant increase in the degree of QT interval dispersion when compared with the healthy population. However it, did not identify patients with induction of ventricular tachycardia in the electrophysiological study, showing a very low predictive value for defining the risk of sudden cardiac death in the population studied.

Selective coronary dye-dilution curves in normal subjects and in patients with coronary disease

Abstract Selective coronary dye-dilution curves were obtained in 24 patients with no clinical evidence of coronary disease and with arteriographically normal coronary arteries and in 20 patients with clinical evidence of coronary disease and significant obstructive disease of the coronary arteries. Cardiogreen, 3.1 mg., was used as an indicator and selectively injected into the ostia of the right and left coronary arteries, with continuous sampling from the main pulmonary artery. The curves for normal subjects showed a fast appearance time, rapid buildup time, tall peak concentration, rapid clearance and mean transit times. The spread ratio was short and peak amplitude/buildup time ratio was prolonged. Major obstructive disease in one or more of the coronary arteries resulted in major alteration in the contour of the dye curves, which exhibited prolonged appearance time, slurrings, notches and “double hump” of the ascending limb, slow buildup time, low peak amplitude and the prolonged mean transit and clearance times. The spread ratio was high and the peak amplitude/buildup time ratio was short. The interplay of three major factors—namely, delay of clearance of the indicator through the localized mechanical obstruction, coronary flow and resistance and extent of collateral circulation—may explain the abnormality of the selective coronary dye-dilution curves. This technic is safe and reproducible, and it is not assocated with any major cardiac arrhythmias or bradycardia. Although more experience with this technic is needed, the present data indicate that this technic may be a useful adjunct in the study of the coronary circulation in man.

Contribuição de eletrocardiografia dinâmica pelo sistema Holter na avaliação de pacientes com a síndrome congênita do QT longo

PURPOSE: The purpose of this study was to evaluate the value of ambulatory electrocardiogram as a clinical tool to assess ventricular repolarization in patients with the congenital long QT syndrome. METHODS: The study population comprised six patients and their data were compared to a control group of six patients matched in age and gender. The QT interval (ms), corrected by the heart rate, was measured in the first minute of each hour using two monitoring leads, with the mean of six consecutives complexes. The data obtained include the morphologic pattern of T wave, the mean 24-h QTc interval, relation between QT and cardiac cycle, QTc variability (assessed calculating hourly standard deviation of the interval and then obtaining the global 24-h mean), QTc dispersion (difference between the longest and shortest QTc interval). RESULTS: In all patients abnormal patterns of T waves were detected with frequent episodes of T wave alternans. Mean 24-h QTc - patients: 598.2±73.8ms; controls: 436.1±8.9ms (p=0.000). Linear correlation and regression between QT and heart rate - patients: r= 0.812; controls: r= 0.967 (p=0.000). QTc variability - patients: 36.9±17.2ms; controls: 14.7±2.1ms (p=0.01). QTc dispersion - patients: 168.3±70.2ms; controls: 53.3±8.1ms (p=0.000). CONCLUSION: The data showed increased hourly QTc variability, QTc dispersion and worse correlation between QT and heart rate. This data may reflect an abnormally augmented ventricular vulnerability.

Modificação do nódulo sinusal via cateter por energia de radiofreqüência em paciente com taquicardia sinusal inapropriada. Avaliação dos resultados imediatos e tardios

This article reports the early and late results of a patient in whom radiofrequency current was used to ablate an incessant inappropriate sinus tachycardia. During successful radiofrequency application there was a sudden change of rate and subsequent emergence of a stable rhythm with the same sinus node P wave characteristics. During follow-up, normal cardiac cycles were still present after six months of the procedure, although the patient still complained of palpitations, suggesting no correlation with the heart rate.

Radiofrequency catheter ablation of an incessant supraventricular tachycardia initiated by a Hisian parasystole.

The coexistence of a pamsystolic focus, tachycardia dependent right bundle branch aberrancy, and an AV accessory pathway is reported here. This condition was present in a 40‐year‐old man, which led to an incessant AV reciprocating tachycardia. Further electrophysiological study revealed that the parasystolic focus was located somewhere in the His bundle; endocardial mapping disclosed a right posterior accessory pathway. Radiofrequency current was delivered at the atrial level of the right posterolateral AV groove and successfully ablated the accessory pathway, leading to a dramatic improvement in cardiac function. In conclusion, the recognition of the electrophysiological mechanism of incessant Supraventricular tachycardia was of crucial importance for the therapy decision. A definitive intervention using radiofrequency catheter ablation should be considered early and not postponed in patients with tachycardia‐induced cardiomyopathy.

Prognostic value of junctional recovery times and long-time follow-up of complete atrioventricular nodal block at a young age

Abstract The main purpose of clinical and electrophysiologic investigation in patients having complete atrioventricular (AV) nodal block is to differentiate between 2 different heterogeneous groups 1 : one presenting with syncope or other bradycardia/tachycardia-related symptoms 2 and the asymptomatic group. The data available at the present time do not allow us to conclude which criteria is the best to distinguish the patient at risk for syncope in the latter group. Even when the site of block is in the proximal part of the His bundle 1 with a good response to parasympathetic blockade 3 or to exercise, 4 the junctional rhythm may not be stable enough, and Adam-Stokes attacks may occur. 5 Some investigators believe that life-expectancy in symptomatic patients can be good. 6 However, others have recognized that life-threatening arrhythmias may develop, 7 and a prophylactic pacemaker should be implanted. 8

Electrophysiologic and clinical implications of induced or not ventricular fibrillation by programmed ventricular stimulation in patients with catecholaminergic polymorphic ventricular tachyarrhythmias

in 24 pts. 2/24 pts died during FU due to heart failure (CHF). VF was induced in 6/26 pts wth DCM and in 5/20 pts with MI. l/l1 pts died due to CHF. Outcome of pts with induced VT and ICD implantation are listed in the table. Conclusion: 1) In 114 of pts with severe heart failure, low ejection fraction and conduction delay a VT was induced. 2) During follow up l/3 of the pts with induced VT and an ICD experienced a spontaneous episode of VTNF. Thus, programmed ventricular stimulation may be considered in all pts with the indication for CRT before implantation to select pts at high risk for arrhythmic events. POSTER SESSION