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Biomedical subjects

G Turitto

Publications and source records attributed to G Turitto.

At least 37 records · Page 2Linked to original sources
PubMed1990

The signal averaged electrocardiogram and programmed stimulation in patients with complex ventricular arrhythmias.

The signal averaged electrocardiogram (SA-ECG), programmed electrical stimulation (PES), and left ventricular ejection fraction (EF) studies were utilized for risk stratification and management of patients with complex ventricular arrhythmias and nonsustained ventricular tachycardia (VT). The study population included 90 patients (63 with coronary artery disease and 27 with dilated cardiomyopathy). Sustained monomorphic VT was induced in 22 cases (24%), ventricular fibrillation (VF) in 10 (11%), and no sustained VT/VF in 58 (64%). An abnormal SA-ECG was recorded in 23 patients (26%) and was more common in patients with than in those without induced sustained VT (68% vs 12%, P less than 0.0001). None of 33 patients with normal SA-ECG and EF greater than or equal to 40% had induced VT. Patients were followed-up for 2.5 +/- 0.8 years off antiarrhythmic therapy, unless they had induced sustained VT. The 3-year sudden death rate was 19% in the group with induced sustained VT, 0 in that with induced VF, and 9% in that without induced VT/VF (P = NS). The 3-year total cardiac mortality was higher in patients with than in those without EF less than 40% (27% vs 7%, P less than 0.05). It is concluded that patients with organic heart disease and spontaneous nonsustained VT may not need PES or antiarrhythmic therapy if SA-ECG is normal and EF is greater than or equal to 40%, since their risk of induced VT and sudden death is low. On the other hand, patients with abnormal SA-ECG and/or EF less than 40% may require PES, since their risk for induced VT is high. Antiarrhythmic therapy may also be considered in these patients.

Action Potentials↗
PubMed1990

Risk stratification and management of patients with organic heart disease and nonsustained ventricular tachycardia: role of programmed stimulation, left ventricular ejection fraction, and the signal-averaged electrocardiogram.

PURPOSE: Programmed stimulation, left ventricular ejection fraction, and signal-averaged electrocardiography were performed in patients with organic heart disease and spontaneous nonsustained ventricular tachycardia (VT) to determine the role of these techniques in risk stratification and management. PATIENTS AND METHODS: The study consisted of 90 patients: 63 had coronary artery disease and 27 had idiopathic dilated cardiomyopathy. Radionuclide ventriculography, signal-averaged electrocardiography, and programmed electrical stimulation were performed in all patients within 48 hours of index ambulatory electrocardiography. RESULTS: Fifty-three patients (59%) had an ejection fraction less than 40%. Programmed stimulation induced sustained monomorphic VT in 22 patients (24%), ventricular fibrillation (VF) in 10 patients (11%), and no sustained VT/VF in 58 patients (64%). The signal-averaged electrocardiogram (ECG) showed late potentials in 23 patients (26%). Sustained monomorphic VT could be induced in 65% of patients with late potentials and in 10% of those without late potentials. There was no case of inducible sustained monomorphic VT in 33 patients with no late potentials and an ejection fraction of 40% or greater. All patients with induced sustained monomorphic VT received antiarrhythmic therapy guided by the results of programmed stimulation. All 58 patients with no induced sustained ventricular tachyarrhythmias and eight patients with induced VF were discharged without receiving antiarrhythmic drugs. During a follow-up of 30 +/- 10 months, the three-year sudden death rate was 19% in patients with induced sustained VT, 0% in those with induced VF, and 9% in those with no induced sustained VT/VF. The three-year sudden death rate was the same (7%) in patients with no induced sustained VT/VF, both in those with an ejection fraction of 40% or greater or less than 40%. On the other hand, the three-year total cardiac mortality was significantly higher (27%) in those patients with ejection fractions less than 40% compared to those with ejection fractions of 40% or greater (7%). CONCLUSION: It is concluded that the signal-averaged ECG, ejection fraction, and programmed stimulation could be used for the risk stratification and management of patients with organic heart disease and nonsustained VT as follows: (1) Patients with no late potentials and with an ejection fraction of 40% or greater do not require invasive evaluation or antiarrhythmic therapy, since the incidences of induced VT and sudden death are very low. (2) Patients with late potentials as well as patients without late potentials but with an ejection fraction of less than 40% may be advised to undergo electrophysiologic evaluation.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Arrhythmia Agents↗
PubMed1989

Prevalence, time course and malignancy of ventricular arrhythmia during spontaneous ischemic ST-segment depression.

Ventricular arrhythmias during transient myocardial ischemia were studied in 60 patients with spontaneous angina and greater than or equal to 1 ischemic attack with ST-segment depression during 24-hour ambulatory electrocardiography. The patients were divided into 2 groups: group 1, 10 patients (17%) who developed ventricular arrhythmias during 26 of 92 (28%) ischemic attacks; and group 2, 50 patients who did not show this phenomenon. Daily ischemic attacks, total ischemic time and the proportion of symptomatic ischemic attacks were significantly greater (p less than 0.01) in group 1 versus group 2. In group 1 patients, ischemic attacks were found to have twice the duration in the presence of arrhythmias than in their absence (20.4 +/- 11.9 vs 9.1 +/- 8.4 minutes, p less than 0.01); arrhythmias were more common during symptomatic than during silent ischemic attacks (39 vs 13%, p less than 0.02). Arrhythmias occurred at the onset or peak of ST-segment depression (ischemia phase) in 6 cases (60%), during the resolution of ST-segment depression (recovery phase) in 2 cases (20%) and during both phases of ischemic attacks in the remaining 2 (20%). When compared to recovery phase arrhythmias, ischemia phase arrhythmias were characterized by a later onset time (173 +/- 144 vs 58 +/- 54 seconds, p less than 0.01) and a longer duration (105 +/- 107 vs 41 +/- 22 seconds, p less than 0.01). During the ischemia phase, 16 of 353 ventricular premature complexes initiated ventricular tachycardia, while during the recovery phase only 1 of 161 ventricular premature complexes resulted in ventricular tachycardia (4.5 vs 0.6%, p less than 0.02). Thus, ventricular arrhythmias may accompany spontaneous ischemic ST-segment depression, when the latter is recurrent, prolonged and symptomatic; arrhythmias are characterized by a greater frequency, duration and malignancy during the ischemia phase than during the recovery phase of ischemic attacks.

Aged↗
PubMed1989

Role of bandpass filters in optimizing the value of the signal-averaged electrocardiogram as a predictor of the results of programmed stimulation.

Normal values for the signal-averaged electrocardiogram (SAECG) at 11 different high-pass filter settings were obtained from 100 normal subjects (group I). The filtered QRS duration and the duration of low amplitude signals less than 40 microV, but not the root mean square voltage of the last 40 ms (RMS40), showed normal distribution. A normal distribution for RMS40 could be obtained by transforming each value to its natural logarithm. The normal values were used in a systematic approach to optimize the accuracy of the SAECG to predict the results of programmed stimulation in 80 patients with spontaneous nonsustained ventricular tachycardia (VT). Fifty-two patients with no inducible VT (group II) and 28 patients with inducible sustained monomorphic VT (group III) were investigated. The 3 SAECG parameters at each high-pass filter in groups II and III were categorized as normal or abnormal and were evaluated singly or in combinations of 2 or 3. There was no combination that provided a sensitivity greater than 82% that could also be obtained by single determinations of low amplitude signals less than 40 microV at 25 to 40 Hz or RMS40 at 40 Hz. On the other hand, there were 267 different combinations that provided a maximal specificity of 98%. The best total predictive accuracy of a single parameter was 85%, provided by RMS40 at 40 or 60 Hz. The total predictive accuracy could be improved to 89% by 1 of 32 different combinations. The top combinations were mostly in triplets and included SAECG parameters recorded at different high-pass filter settings. The only 2 paired combinations with the best total predictive accuracy were RMS40 at 20 or 25 Hz paired with RMS40 at 40 Hz. Frequencies at both ends of the analyzed high-pass filter settings (less than 20 Hz and greater than 60 Hz) were not represented in the top predictive combinations. The SAECG parameters analyzed at 40 Hz were most frequently represented in the top predictive combinations, suggesting that the SAECG may have the best predictive accuracy at this filter setting. In summary, the combination of SAECG parameters analyzed at different filter settings can enhance the accuracy of the technique as a screening test for the results of programmed stimulation in patients with spontaneous nonsustained VT.

Adult↗
PubMed1989

Prognostic significance of the signal-averaged ECG depends on the time of recording in the postinfarction period.

Serial recordings of the signal-averaged ECG and the 24-hour ambulatory ECG were obtained from 156 patients with acute myocardial infarction up to 5 days (phase 1), 6 to 30 days (phase 2), and 31 to 60 days (phase 3) after the infarction. Left ventricular ejection fraction by radionuclide ventriculography was also determined in phase 2. The signal-averaged ECG was abnormal during one or more of the three phases in 51 patients (31%). In 35 of these patients (69%) the recording changed category between normal and abnormal with the highest prevalence of abnormal recording occurring during phase 2. Eight patients had ventricular tachycardia/ventricular fibrillation in the first 48 hours after myocardial infarction. The signal-averaged ECG was abnormal in only one of these patients. Twelve patients had late arrhythmic events during the first year of follow-up (four sudden deaths and eight instances of documented ventricular tachycardia or ventricular fibrillation). Nine of the 12 patients had an abnormal signal-averaged ECG in phase 2 and four of these nine had a normal recording in phase 1. Five patients had a transient abnormal signal-averaged ECG in phase 1, whereas six patients had an abnormal recording only in phase 3. None of these 11 patients had an arrhythmic event. Stepwise logistic regression showed that an abnormal signal-averaged ECG in phase 2 has the most significant relation to late arrhythmic events. Both an abnormal signal-averaged ECG and a left ventricular ejection fraction less than 40%, but not complex ventricular arrhythmias, were independent significant risk factors for late arrhythmic events.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Negative post-ischemic T waves in variant angina].

The clinical and prognostic significance of negative T waves on the basal electrocardiograms of patients with unstable angina has been recently investigated with controversial results. Moreover, there is little data regarding this phenomenon in patients with variant angina. In order to evaluate the significance of negative post-ischemic T waves in patients with variant angina, 72 patients underwent Holter recording and coronary angiography. Negative T waves were present in 38 out of 72 patients (53%): they were anterior in 24 cases and inferior in 14 cases. The negative T-wave phenomenon was present in 29 patients on admission and showed up in 9 patients during hospitalization. Holter recording showed no significant differences between patients with or without negative T waves with regards to: 1) the proportion of symptomatic transient myocardial ischemic attacks; 2) the frequency of arrhythmias during transient myocardial ischemic attacks; 3) the maximum duration of transient myocardial ischemic attacks; 4) the maximum degree of ST elevation during transient myocardial ischemic attacks. Negative T waves on the anterior leads showed a moderate sensitivity (54%) and total predictive accuracy (52%), as well as a lower specificity (43%) and negative predictive accuracy (15%) for a significant stenosis of the left anterior descending coronary artery. This was due to the presence of several patients with left anterior descending artery stenosis and without negative T waves. On the other hand, negative T waves on the inferior leads were characterized by high sensitivity (85%), specificity (80%) and total predictive accuracy (82%) for a significant stenosis of the right coronary artery and/or the circumflex artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris, Variant↗
PubMed1988

Value of the signal-averaged electrocardiogram as a predictor of the results of programmed stimulation in nonsustained ventricular tachycardia.

A prospective assessment of several clinical variables, left ventricular function indexes, Holter recording characteristics and signal-averaged electrocardiogram (ECG) for their value in predicting the inducibility of sustained ventricular tachyarrhythmias was carried out in a consecutive series of 105 patients with nonsustained ventricular tachycardia (VT). The patients were divided into 3 groups based on the results of programmed electrical stimulation: group 1, 22 patients with induced sustained monomorphic VT; group 2, 14 patients with induced ventricular fibrillation (VF) and group 3, 69 patients with no induced sustained VT/VF. Left ventricular ejection fraction less than 0.40, history of syncope/presyncope and abnormal signal-averaged ECG were significantly more common in group 1 than in group 3. No significant difference was found between groups 2 and 3. The sensitivity, specificity and predictive accuracy of the signal-averaged ECG for the induction of sustained monomorphic VT were 64, 89 and 84%, respectively. Using stepwise discriminant function analysis, the signal-averaged ECG was found to be the single most accurate screening test to predict the inducibility of sustained VT in patients with nonsustained VT and its value was independent of the etiology of heart disease and the length of spontaneous runs. Because of the very high specificity and negative predictive accuracy, patients with normal signal-averaged ECGs may not require invasive evaluation.

Cardiac Pacing, Artificial↗
PubMed1988

Initiation of ventricular fibrillation by supraventricular beats in patients with acute myocardial infarction.

The role of supraventricular extrasystoles in the initiation of ventricular arrhythmia was studied in 72 consecutive patients who developed primary ventricular fibrillation during the acute phase of myocardial infarction. In six patients (8%), a total of 12 episodes of ventricular fibrillation and 16 episodes of ventricular tachycardia were initiated by supraventricular extrasystoles. Ventricular fibrillation and tachycardia were initiated by single supraventricular extrasystoles in 16 and by salvos greater than or equal to two beats in 12 episodes. The RR coupling interval of the supraventricular impulse immediately preceding ventricular tachycardia ranged from 240 to 420 ms (mean 356 (62)) and was characteristic of R-on-T (prematurity index less than 1) in 63% of episodes. Average peak serum creatine kinase activity in the six patients in whom ventricular tachycardia was initiated by a supraventricular extrasystole was 1275 units compared with 720 units in the remaining 66 patients. Five of these six patients later showed evidence of pump failure. Lignocaine or procainamide or both suppressed the ventricular arrhythmia in five of the six patients. The initiation of ventricular fibrillation or tachycardia by supraventricular extrasystoles in acute myocardial infarction is not uncommon and may reflect the increased vulnerability of the heart after a large infarct. These arrhythmias may respond to drugs that suppress ventricular irritability.

Cardiac Complexes, Premature↗
PubMed1988

Time course of ventricular arrhythmias and the signal averaged electrocardiogram in the post-infarction period: a prospective study of correlation.

The incidence and time course of complex ventricular arrhythmias and of the abnormal signal averaged electrocardiogram were studied prospectively in 90 patients in the first two months after acute myocardial infarction. Serial recordings of both 24 hour ambulatory and signal averaged electrocardiograms were obtained 0-5 days (phase 1), 6-30 days (phase 2), and 31-60 days (phase 3) after infarction. A total of 264 ambulatory electrocardiograms and 264 signal averaged electrocardiograms were available for analysis. Complex ventricular arrhythmias were seen in 31%, 17%, and 38% of patients during phases 1, 2, and 3 respectively, and abnormal signal averaged electrocardiogram in 13%, 24%, and 16%. The incidence of complex ventricular arrhythmias was not significantly different in patients with or without an abnormal signal averaged electrocardiogram in the entire study period nor in any of the three phases after infarction. During phase 2 when abnormal signal averaged electrocardiograms were most common complex ventricular arrhythmias were least common. This lack of correlation suggests that the abnormal signal averaged electrocardiogram and complex ventricular arrhythmias after infarction have different electrophysiological bases.

Adult↗
PubMed1988

Alternans of the ST segment in variant angina. Incidence, time course and relation to ventricular arrhythmias during ambulatory electrocardiographic recording.

The ST alternans was recorded during at least one ischemic attack with ST elevation in nine of 65 patients with variant angina. The magnitude and duration of ST elevation during ischemic attacks were significantly greater in patients with than in those without ST alternans. It always appeared during the occlusion phase and disappeared during the reperfusion phase of ischemic attacks. In patients with episodic ST alternans, the ischemic attacks showed a greater ST elevation and a longer duration in the presence of ST alternans than in its absence. The incidence of occlusion phase ventricular arrhythmias was greater in patients with than in those without ST alternans; the incidence of reperfusion phase ventricular arrhythmias was similar in the two groups. The ST alternans always preceded the onset of occlusion phase arrhythmias. Thus, in variant angina, ST alternans represents an index of the severity of ischemia and a precursor of ventricular arrhythmias.

Angina Pectoris, Variant↗
PubMed1988

Risk stratification of patients with complex ventricular arrhythmias. Value of ambulatory electrocardiographic recording, programmed electrical stimulation and the signal-averaged electrocardiogram.

Currently, there are three prognostic indicators of ventricular electrical instability: long-term ambulatory ECG recording, programmed electrical stimulation and the signal-averaged electrocardiogram. Several clinical studies have suggested that frequent and complex ventricular premature contractions in patients with organic heart disease may identify future cardiac events, including sudden cardiac death although, with respect to prognosis, it is not likely that any grading system based on the ambulatory ECG will be without meaningful limitations. No study has adequately tested the hypothesis that decreasing ventricular arrhythmias after acute myocardial infarction reduces mortality. The inducibility of ventricular tachycardia during programmed electrical stimulation is regarded as an independent risk factor for sudden death. Predominantly due to the lack of standardized protocol and definitions, the actual relevance of current literature remains somewhat compromised. The indication for antiarrhythmic treatment in those patients in whom ventricular tachycardia can be induced has not been established with certainty since the effects of therapy on the prognosis are unknown. For patients with complex ventricular arrhythmias in whom sustained ventricular tachycardia cannot be induced, antiarrhythmic drug treatment does not appear indicated. Based on a number of studies, the presence of late potentials in the signal-averaged ECG has also been shown to be a meaningful prognostic indicator. The signal-averaged ECG, however, is not only subject to various technical problems but is also encumbered by limitations arising from electrophysiologic considerations. While no relationship could be established between late potentials and complex ventricular arrhythmias in the ambulatory ECG within the first two months after acute myocardial infarction, there was, however, a correlation between late potentials and the inducibility of ventricular tachycardia during programmed electrical stimulation. Consequently, the signal-averaged ECG may serve as a screening test to identify patients who should subsequently undergo programmed electrical stimulation for arrhythmia assessment or guided institution of treatment provided this proves to be effective in reducing the risk of future major arrhythmic events.

Cardiac Complexes, Premature↗
PubMed1987

Antiarrhythmic effects of oral indecainide in patients with ventricular tachyarrhythmias.

In order to assess the efficacy and safety of oral indecainide in patients with serious ventricular arrhythmias we studied 11 patients with high-grade ventricular ectopy and ventricular tachycardia (VT) which were refractory to therapy with at least one standard antiarrhythmic drug. Spontaneous arrhythmias were quantitated by 24-h Holter monitor before and during therapy with indecainide. Spontaneous VT was sustained in 4 patients and nonsustained in 7. Ten patients underwent baseline electrophysiologic study (EPS) and VT was induced in 9. The mean ejection fraction was 25 +/- 14%. Indecainide was given orally at a dose of 211 +/- 118 mg/day. The frequency of ventricular premature beats (VPBs) was significantly (greater than 85%) decreased in 90% of patients, while ventricular couplets frequency decreased in 78%. Spontaneous VT was abolished in 5 of 11 (45%). Sustained VT was induced in 5 of 7 (71%) patients who underwent follow-up EPS. The QRS duration was significantly prolonged during therapy (0.13 +/- 0.04 s) compared to control (0.10 +/- 0.02 s). The PR, QTc, and JTc intervals were not significantly changed. Indecainide was well tolerated, but 2 patients died of ventricular tachyarrhythmias while receiving the drug. Indecainide suppressed VPBs in a high percentage of patients, but was much less successful in controlling VT. Caution is necessary when using this drug because of its potential for exacerbation of arrhythmia.

Aged↗
PubMed1985

[Diltiazem in spontaneous angina: comparison with nifedipine and verapamil].

Sixteen patients with spontaneous angina were studied to assess the relative efficacy of diltiazem (D) at different doses [240 mg/day (D240) versus 360 mg/day (D360)], nifedipine (N: 120 mg/day), and verapamil (V: 480 mg/day), given according to a latin-square protocol. Of the 16 patients, 6 had ischemic attacks with ST elevation, 6 had ischemic attacks with ST depression, 4 showed ST elevation or ST depression in different ischemic attacks. All the patients underwent 24-hour Holter monitoring: at the beginning of the study; during the third day of treatment with D240, D360, N or V; after the withdrawal of each treatment. An atrioventricular block was observed in 2 patients during treatment with V, and in 1 patient during treatment with D240 and D360. In the remaining cases, D and V significantly (p less than 0,05) prolonged the PR interval (D240: + 18%; D360: + 16%; V: + 20%), and reduced the mean daily heart rate (D240: -9%; D360: -12%; V: -11%). The effects of D and V were statistically not different. All the treatments significantly reduced the frequency of the ischemic attacks (p less than 0,05) (D240: -79%; D360: -93%; N: -90%; V: -90%). In particular, D240 reduced by the same percentage (-79%) the frequency of ischemic attacks with ST elevation and ST depression, while D360 completely abolished ischemic attacks with ST elevation and reduced by 79% those with ST depression. Our results suggest that: diltiazem is highly effective in the treatment of spontaneous angina; the efficacy of 360 mg/day of diltiazem is equivalent to that of 120 mg/day of nifedipine and of 480 mg/day of verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Characterization and therapy of ventricular arrhythmias due to transient myocardial ischemic attacks in variant angina].

Forty-two patients with variant angina were studied by ambulatory ECG monitoring to determine the incidence and the characteristics of ventricular arrhythmias during ischemic attacks. Twenty-six patients had no ventricular arrhythmias in 633 ischemic attacks; 16 patients had ventricular arrhythmias in 116/586 ischemic attacks. The number of ischemic attacks per day and the magnitude of ST elevation were significantly (p less than 0.05) greater in patients with ventricular arrhythmias. Ventricular arrhythmias appeared at the onset or at the peak of ST elevation (first phase) in 17 ischemic attacks, during the resolution of ST elevation (second phase) in 43 attacks, during both the phases in 9 attacks. ST alternans appeared during 6 ischemic attacks with arrhythmias. Two episodes of ventricular fibrillation and 22 runs of ventricular tachycardia occurred during the first phase, 17 episodes of ventricular tachycardia were recorded during the second phase. Ventricular tachycardia of the second phase compared with ventricular tachycardias of the first phase were significantly (p less than 0.01) slower, uniform and initiated by a late premature beat. Incidence of arrhythmias of the second phase was strictly correlated with the duration of ischemic attacks. Nine patients who showed ventricular arrhythmias during the second phase of ischemic attacks were enrolled in a cross-over study to assess the antiarrhythmic effects of nifedipine (120 mg/day) and verapamil (480 mg/day). During treatment with nifedipine, the frequency of ischemic attacks declined by 85%, while the frequency of attacks with arrhythmias declined by 97% (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗