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Biomedical subjects

C Pandozi

Publications and source records attributed to C Pandozi.

29 records · Page 2Linked to original sources
PubMed1997

Influence of digital and analogue cellular telephones on implanted pacemakers.

UNLABELLED: The aim of this study was to find out whether digital and analogue cellular 'phones affect patients with pacemakers. The study comprised continuous ECG monitoring of 200 pacemaker patients. During the monitoring certain conditions caused by interference created by the telephone were looked for: temporary or prolonged pacemaker inhibition; a shift to asynchronous mode caused by electromagnetic interference; an increase in ventricular pacing in dual chamber pacemakers, up to the programmed upper rate. The Global System for Mobile Communications system interfered with pacing 97 times in 43 patients (21.5%). During tests on Total Access of Communication System telephones, there were 60 cases of pacing interference in 35 patients (17.5%). There were 131 interference episodes during ringing vs 26 during the on/off phase; (P < 0.0001); 106 at maximum sensitivity level vs 51 at the 'base' value; P < 0.0001). Prolonged pacing inhibition (> 4 s) was seen at the pacemaker 'base' sensing value in six patients using the Global system but in only one patient using Total Access. CONCLUSION: Cellular 'phones may be dangerous for pacemaker patients. However, they can be used safely if patients do not carry the 'phone close to the pacemaker, which is the only place where high risk interference has been observed.

Adult↗
PubMed1997

[Electrophysiologic characteristics of the atrium during chronic atrial fibrillation in man].

AIM OF THE STUDY: To evaluate the electrophysiologic characteristics of human atria during chronic atrial fibrillation. METHODS: The study was performed in 24 patients who underwent low energy intracardiac atrial cardioversion for chronic atrial fibrillation before the procedure itself. No patients have been assuming antiarrhythmic drugs for a period of at least 5 half-lives of the drug. In 10 patients the possibility of local capture in several atrial sites (7 tested) by means of high-rate atrial pacing was evaluated. A Franz catheter for recording of monophasic action potential (MAP) and for atrial stimulation was positioned in the right atrium at a distance of 1 cm from a quadripolar catheter which was also positioned for the recording of the bipolar electrogram by the distal and proximal pairs and of the unipolar electrogram by the distal electrode. A decapolar catheter for shock delivery was positioned in the coronary sinus as well. In the remaining 14 patients an additional quadripolar catheter for His recording was positioned but atrial stimulation was not performed. Furthermore, recordings of the bipolar and unipolar electrograms were obtained in several sites and the correlation between MAP and bipolar electrogram morphology was evaluated. The existence of a difference in fibrillation cycle-length in different sites suggestive of a dispersion of refractory periods was also screened. Wells' and Waldo's classification was used for bipolar electrograms whereas MAP was classified into type 1 (regular), type 2 (partially irregular), and type 3 (totally irregular). RESULTS: In 10 patients submitted to atrial stimulation, local capture was obtained in 37 out of 43 stimulation sites (86%). Local capture was more frequently obtained in the lateral wall than in other sites (p < 0.05). The capture was obtained only in type 1 and type 2 atrial fibrillation. In the remaining 14 patients a perfect correlation (100%) between type 1 and 3 atrial fibrillation and type 1 and 3 MAP respectively was observed. In type 2 atrial fibrillation the correspondence was lower (67%). Fibrillation cycle-length contemporary recorded in the 6 different atrial sites were significantly different in 8 patients out of 12 (67%) in whom a stable recording could be obtained in basal conditions. CONCLUSIONS: 1) In chronic atrial fibrillation an excitable gap allowing local capture is present in the majority of patients and in most atrial sites, at least in the right atrium. 2) The morphology of bipolar and MAP recordings are fairly correlated and they reflect the complexity and the degree of synchronization of the arrhythmia. 3) A dispersion of refractoriness seems to contribute to the maintainance of the arrhythmia.

Action Potentials↗
PubMed1997

[Latent long QT syndrome: discription of a clinical case].

Latent forms of long QT syndrome have been already reported. We describe one case of a 27 years old female patient who experienced an episode of cardiac arrest after several puffs of salbutamole. The malignant arrhythmia causing the cardiac arrest was torsade de pointes degenerated into ventricular fibrillation. The patient ECG showed a normal QTc basal interval and the correct diagnosis was made by contemporary recording of the ECG and MAP during orciprenalina infusion. After drug infusion, we have recorded a MAP lengthening and a dispersion of MAP duration between the right ventricular apex and the right ventricular outflow tract. These modifications were concomitant with the appearance of "humps" (probably related to the presence of early afterdepolarizations), a QT interval lengthening and morphologic changes of the T and U waves.

Administration, Inhalation↗
PubMed1997

[Acute effects of ventricular and bicameral stimulation on plasma levels of natriuretic hormone].

Atrial natriuretic factor (ANF) is a peptide produced by the atrium in response to increases in atrial pressure. It is a potent vasodilator and recent studies suggest that ANF may modulate vasomotor changes in patients (pts) with pacemaker (PM) syndrome. To evaluate the incidence of pacing mode on peptide secretion, plasma concentrations of ANF were determined in 32 pts (18 men and 14 women, mean age 71 +/- 4 years) with a DDD PM implant. Blood samples were collected one hour after a randomly assigned PM programming either in VVI or DDD mode at 70 ppm. Mean plasma ANF levels were 84.12 +/- 51 pg/ml in DDD mode and 156.0 +/- 15 pg/ml in VVI mode (p < 0.05). In 12 pts presenting ventriculoatrial retroconduction, the ANF levels were 77.16 +/- 50 pg/ml during DDD stimulation and 219.0 +/- 16 pg/ml during VVI stimulation (p < 0.05). ANF level was 88.50 +/- 46 pg/ml in DDD mode and 114.25 +/- 65 pg/ml in VVI mode in the 20 pts without AV retroconduction (p < 0.05). During DDD mode, 18 patients showed a DVI stimulation whereas 14 showed a VDD stimulation: the mean ANF level was 67.40 +/- 15 pg/ml during DVI and 100.40 +/- 28 pg/ml during VDD stimulation; the difference between these data was not significant. The increase in ANF levels during VVI pacing confirms the lower haemodynamic performance of this stimulation mode. The increase of ANF levels during VVI stimulation, which was in the subgroup without AV retroconduction, confirms the benefits of DDD stimulation also in this group of patients as well. Atrial pacing at physiological rates does not trigger the release of ANF.

Aged↗
PubMed1996

Indications for dual-chamber (DDD) pacing in implantable cardioverter-defibrillator patients.

New technologic development of implantable cardioverter-defibrillators (ICDs) keeps up with the exponential increase of their use for primary and secondary prevention of sudden cardiac death. The first-generation ICD with limited shock capability alone could be considered adequate in most cardiac arrest victims, but it was not suitable for sudden death prevention in all high-risk patients with cardiac disease. The second-generation ICD was comprised of hybrid pacemaker-defibrillator systems that provided on-demand ventricular antibradycardia pacing. The third-generation devices include additional functions, such as antitachycardia pacing for ventricular tachycardia (VT) reversion and low-energy ventricular cardioversion, in addition to ventricular defibrillation and single-chamber ventricular demand pacing. In the near future, advanced dual-chamber atrioventricular (AV) pacing and defibrillating systems will also be available. The dual chamber ICD will allow atrial inhibited/dual-chamber (AAI/DDD) rate-responsive pacing, simultaneous atrial and ventricular sensing to optimize the arrhythmia identification, and ICD shock delivery in the proper arrhythmia-related chamber. Clinical benefits of these devices compared with their cost and complexity will require careful evaluation.

Cardiac Pacing, Artificial↗
PubMed1996

[Ventricular nodal reentry tachycardia without ventricular dilatation: diagnosis and treatment by radiofrequency catheter ablation].

Bundle branch reentry tachycardia has been reported in patients with left ventricular dilatation, especially in those with dilated cardiomyopathy and aortic regurgitation. These patients show aspecific intraventricular conduction delay on the ECG and a prolonged H-V interval at the electrophysiologic study. We report 2 cases of bundle branch reentry tachycardia in patients without left ventricular enlargement to help the correct diagnosis of the arrhythmia. A correct diagnosis is very important because bundle branch reentry tachycardia is easily and safely treated by right bundle transcatheter radiofrequency ablation. We also report electrophysiologic characteristics we found during the study and the ablation: -contrary to the data reported in literature, at ventricular tachycardia starting, modifications of the V-V interval are not always preceded by similar variations in the H-H interval. -during right bundle radiofrequency ablation, a QRS narrowing may precede right bundle branch block appearance. This QRS normalisation should induce to continue and not to stop energy delivering.

Aged↗
PubMed1995

Transthoracic DC shock may represent a serious hazard in pacemaker dependent patients.

External defibrillation is widely used for the termination of various atrial and ventricular tachyarrhythmias, including pacemaker patients. Our study was intended to evaluate the effects of DC shocks in 36 patients with unipolar pacemakers implanted in the right pectoral region (25 DDD, 10 VVI, 3 AAI). The shocks were delivered with paddles on the anterior surface of the thorax, as far as possible away from the pacemaker. The pacing output was programmed at 0.5 msec and 5 V (25 patients), 4 V (1 patient), and 2.5 V (10 patients). Transient loss of capture occurred in 18 patients (50%). These patients, compared with those without capture failure, received higher peak and cumulative shock energies, respectively, 216 +/- 99 versus 123 +/- 50 joules (P < 0.002) and 352 +/- 62 versus 147 +/- 98 joules (P < 0.004) and had a lower pacemaker pulse amplitude (4.0 +/- 1.2 vs 4.6 +/- 1.0 V, P = 0.11). Failure to capture lasted from 5 seconds to 30 minutes (mean 157 sec). In 15 patients the ventricular stimulation threshold was measured before and serially after cardioversion. A six-fold threshold increase was observed 3 minutes after the shock (P < 0.004) with gradual recovery to nearly baseline values at 24 hours. Transient sensing failure occurred in 7 of the 17 patients in whom it could be evaluated (41%). Furthermore, three cases of shock induced pacemaker malfunctions were observed requiring replacement of the stimulator in two patients. In conclusion, the incidence of loss of capture in pacemaker patients subjected to electrical cardioversion/defibrillation is high.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1983

[Prognostic evaluation with invasive technics in patients with hyperkinetic ventricular arrhythmias].

The prognostic value of induction of ventricular tachycardia (VT) by programmed electrical stimulation (PES) was analyzed in 123 patients: 64 (Group I) with spontaneous recurrent VT and 59 (Group II) without a history of serious arrhythmias. Thirty-three patients with spontaneous VT underwent coronary and left ventricular angiography to compare electrical instability with the presence of ventricular disfunction and/or the extent of coronary artery disease (CAD). PES reproducibly induced VT in 49/64 patients with spontaneous VT (sensitivity = 77%) and in 6/59 patients without VT (specificity = 90%). Twenty-two patients (66%) had ventricular disfunction defined by an ejection fraction of less than or equal to 40% or regional wall motion abnormalities. Only 4 patients (33%) had proximal 3-vessel CAD. The mean follow-up period was 16 +/- 12 months. Eight of Group I patients died suddenly and 24 had recurrent symptomatic VT. Three of Group I patients died (1 cardiac failure, 2 non-cardiac deaths), all the survivors were free of serious arrhythmias. In Group I patients mortality was correlated with: recent anterior myocardial infarction, inducible sustained VT with PES, ejection fraction less than or equal to 0.40, ventricular ipoasynergy and or at least one coronary stenosis greater than or equal to 70%. This study suggests that inducible VT is a marker of the risk of sudden death. Electrical instability may occur independent from the etiology of cardiopathy, ventricular disfunction and extent of CAD, but these parameters are correlated to global and sudden mortality in the group of patients with spontaneous VT.

Adult↗
PubMedDate not supplied

Electrophysiological characteristics of the human atria after cardioversion of persistent atrial fibrillation.

BACKGROUND: In animal models, induced atrial fibrillation shortens the atrial effective refractory period (ERP) and reverses its physiological adaptation to rate. It is not clear whether this process, known as "electrical remodeling," occurs in humans. METHODS AND RESULTS: We determined the ERPs, at 5 pacing cycle lengths (300 to 700 ms) and in 5 right atrial sites, after internal cardioversion of chronic atrial fibrillation in 25 patients (14 in pharmacological washout and 11 on amiodarone). The ERPs were 195.5+/-18.8 ms in the washout and 206.3+/-17.9 ms in the amiodarone patients (P<0.0001). ERPs were closely correlated with the stimulation rates (r=0.95 in the washout and r=0.94 in the amiodarone group), and slope values indicating a normal (>/=0.07) or nearly normal (0.05 to 0.06) adaptation of ERP to rate were found in 77% of the 84 paced sites. The mean ERP was shorter in the lateral wall (198.1+/-17.9 ms) than in the atrial roof (203.3+/-21.5 ms) and in the septum (210.5+/-20.0 ms) (P<0.03). After 4 weeks of sinus rhythm, the mean ERP, determined again in 8 patients (4 in wash-out and 4 on amiodarone), was significantly increased compared with the basal study (221. 4+/-21.4 versus 197.8+/-18.3 ms, P<0.0001). CONCLUSIONS: After cardioversion of chronic atrial fibrillation, (1) atrial ERP adaptation to rate was normal or nearly normal in the majority of the cases, (2) a significant dispersion of refractoriness between different right atrial sites was present, and (3) ERPs were significantly increased after 4 weeks of sinus rhythm in both washout and amiodarone patients.

Adaptation, Physiological↗