Biomedical subjects

A Natale

Publications and source records attributed to A Natale.

At least 91 records · Page 5Linked to original sources

PubMed1995

Efficacy of different treatment strategies for neurocardiogenic syncope.

OBJECTIVES: The purpose of this study was to evaluate the efficacy of different therapeutic approaches for patients with a history of syncope and positive head-up tilt testing. BACKGROUND: Head-up tilt testing has gained broad acceptance as a reliable diagnostic method for the assessment of patients with recurrent unexplained syncope. However, once the diagnosis is established, there is no consensus on the most appropriate treatment. In this respect, efficacy of drug therapy in preventing recurrence of symptoms in such patients is not entirely clear, and controversies exist regarding the need to confirm the effects of pharmacological interventions. METHODS: Clinical follow-up was obtained in 303 patients with a history of syncope and positive head-up tilt testing. After the diagnostic head-up tilt, patients were assigned to different therapeutic approaches according to their preference or logistic impediments. Of 303 patients, 44 received empiric therapy, 210 were treated with medications proven effective during repeated head-up tilt testing, and 49 refused or discontinued medical therapy. The three groups were similar with regard to age, sex, and clinical presentation. The mean follow-up was 2.8 +/- 1.8 years. Among the patients treated according to head-up tilt guided therapy, 130 were on beta blockers, 35 on theophylline, 10 on ephedrine, 31 on disopyramide, and 4 on miscellaneous regimens. Empiric treatment consisted of beta blockers in 37 of 44 patients and other drugs in the remaining patients. RESULTS: During the follow-up, recurrence of symptoms was experienced in 12 (6%) of the 210 patients receiving the head-up tilt guided therapy, 16 (36%) of 44 in the empiric therapy group, and 33 (67%) of 49 in the no therapy group. Recurrence of symptoms in patients on empiric or no therapy was significantly more frequent as compared to the head-up tilt guided therapy group (P < 0.01). CONCLUSIONS: In patients with unexplained syncope and positive upright tilt testing, therapeutic strategies identified on the basis of response during head-up tilt have a more positive impact on the recurrence of symptoms during follow-up.

Adolescent↗

PubMed1995

Sensing failure in a tiered therapy implantable cardioverter defibrillator: role of auto adjustable gain.

Implantable cardioverter defibrillators have an established role in the management of life-threatening tachyarrhythmias. These devices use sophisticated sensing circuitry to detect and promptly treat a vast majority of these arrhythmias. However, they are not foolproof. We report one case where the device failed to sense every other QRS complex during induced ventricular fibrillation due to marked electrical alterans. Thus, undersensing can be a potentially fatal problem despite the use of auto adjustable gain.

Aged↗

PubMed1995

[Acute pancreatitis: clinical-tomographic correlations].

The authors are interested in verifying the correlation between clinical findings and CT scan imaging in acute pancreatitis. Forty-one patients with acute episodes of pancreatitis are studied according to classic clinical Ranson prognostic factors and radiological Hill classification. All patients are investigated with G.E. 9800 Quick TC scanner. Our data show a significant correlation especially for patients of extreme classes: 78.3% of patients in first Ranson class are included in 0-I-II Hill grades, 74% of the patients in the cumulative third and fourth Ranson classes are correlated with IV and V Hill grades. Finally the authors underline the usefulness of clinical and tomographic evaluation for prognostic and therapeutical trends in patients with acute pancreatitis.

Acute Disease↗

PubMed1994

Circulatory and catecholamine changes during head-up tilt testing in neurocardiogenic (vasovagal) syncope.

Changes in heart rate, arterial pressure, norepinephrine and epinephrine levels were compared in 19 consecutive patients (10 men and 9 women, mean age 46 +/- 16 years) with neurocardiogenic syncope and 11 age- and sex-matched control subjects (5 men and 6 women, mean age 49 +/- 15 years) during head-up tilt testing. Norepinephrine and epinephrine levels were measured at the baseline supine position, in the initial upright position, every 90 seconds during the 70 degrees upright tilt, at the time of termination due to hypotension and syncope (or at 15 minutes in control subjects), and at 40 seconds and 1 minute and 40 seconds in the supine position after terminating the head-up tilt test. Baseline norepinephrine, epinephrine and heart rate were slightly higher in patients. Despite a significant decrease in mean arterial pressure during head-up tilt testing in patients (51 +/- 20 mm Hg; p < 0.001), norepinephrine levels in patients and control subjects at the time of terminating the head-up tilt test were comparable (459 +/- 204 vs 473 +/- 172 pg/ml). A fivefold increase in epinephrine levels (73 +/- 53 to 345 +/- 260 pg/ml; p < 0.01) were seen in patients, whereas control subjects had insignificant change (38 +/- 16 to 65 +/- 44 pg/ml). It is concluded that diminished neuronal sympathetic activity and enhanced adrenomedullary activity is demonstrated during head-up tilt testing in patients with neurocardiogenic syncope.

Adult↗

PubMed1994

Electrophysiologic effects of amlodipine vs. diltiazem in patients with coronary artery disease and beta-blocking therapy.

This study compares the electrophysiologic effects of amlodipine and diltiazem in patients with coronary artery disease concomitantly treated with background beta-blocking therapy. Thirty patients were included in an open-label parallel study in two phases. During phase 1, patients were screened and placed on maintenance atenolol therapy at 50 or 100 mg/day, while phase 2 consisted of right-sided catheterization and randomization of patients to either amlodipine (10 mg i.v.) or diltiazem (10 mg i.v.). Following treatment with amlodipine, no significant alteration in markers of electrophysiological activity was observed. Treatment with diltiazem resulted in a significant lengthening of sinus cycle length (SCL, p < 0.04), AH interval (p < 0.02), and Wenckebach CL (WCL, p < 0.001), and a trend towards an increase in sinus node recovery time (SNRT, p = 0.057). No effects were observed with regard to HV interval and corrected SNRT. The results of this study indicate that 10 mg intravenous amlodipine has no significant electrophysiological action on sinus or AV node function in patients receiving beta-blocker therapy with atenolol, suggesting that amlodipine can be added to beta-blockers to treat patients with myocardial ischemia and/or hypertension without any significant increase in the risk of bradyarrhythmias.

Adult↗

PubMed1994

Efficacy and safety of atrioventricular nodal modification for atrioventricular nodal reentrant tachycardia in the pediatric population.

The safety and efficacy of radiofrequency catheter modification of the atrioventricular node for atrioventricular nodal reentrant tachycardia in the pediatric population is described. Twenty-one patients with a mean age of 14.9 +/- 3.6 years underwent slow-pathway atrioventricular nodal modification with a stepwise anatomic approach. The average cumulative fluoroscopy exposure time (22 procedures in 21 patients) inclusive of the electrophysiologic study was 36.1 +/- 22 minutes. Noninducibility of tachycardia was achieved in all patients with one procedural complication (hemothorax). During a mean follow-up of 15 +/- 9.06 months, tachycardia recurred in one patient. Patient and family acceptance and satisfaction with the procedure was high. Because of the curative potential of radiofrequency catheter modification with low associated short- and long-term risks, it may be considered as a primary treatment option in pediatric patients with symptomatic atrioventricular nodal reentrant tachycardia.

Adolescent↗

PubMed1994

Preliminary experience with a hybrid nonthoracotomy defibrillating system that includes a biphasic device: comparison with a standard monophasic device using the same lead system.

OBJECTIVES: This study analyzed the advantage of combining a biphasic device with a transvenous system and compared the results with those obtained with a standard monophasic device. BACKGROUND: Available lead systems use monophasic pulses and may require lengthy intraoperative testing to achieve adequate defibrillation threshold in a conspicuous number of patients. The option of biphasic waveform may provide further benefits. However, clinical experience with a permanent implant is lacking. METHODS: Fifty-five patients underwent testing and received a permanent implant using the Endotak lead system associated with a CPI monophasic device. The remaining 36 patients received a permanent implant with the Endotak lead system connected to a biphasic device. In both groups a subcutaneous patch was combined when needed to obtain acceptable defibrillation thresholds. RESULTS: Biphasic pulses resulted in lower mean (+/- SD) defibrillation thresholds (monophasic 15 +/- 4.7 J vs. biphasic 12 +/- 5 J, p = 0.03) and a better implantation rate (100% biphasic vs. 89% monophasic, p = 0.07). Biphasic pulses allowed implantation with less ventricular fibrillation induction (7.4 +/- 3.2 vs. 3.5 +/- 1.8, p < 0.01) and a mean shorter procedure time (168 +/- 39 vs. 111 +/- 30 min, p < 0.01). With the biphasic waveform a greater proportion of patients met the implantation criteria with the lead system alone (83% vs. 45%, p < 0.01). When needed, the left prepectoral location of the patch electrode was always sufficient in left subscapular position was required in 15 patients in the monophasic group. Implantation of the biphasic device was associated with a shorter mean hospital stay (3.8 +/- 0.8 vs. 5.4 +/- 2.2 days, p < 0.01). CONCLUSIONS: Incorporation of a biphasic device in a transvenous implantable cardioverter-defibrillator uniformly increases the efficacy of the system and the ease of implantation.

Adult↗

PubMed1994

Mothers' causal explanations for their son's schizophrenia: relationship to depression and guilt.

This study investigated the relationship between mothers' causal explanations for their son's schizophrenia and the depression and guilt mothers experience. Thirty-three mothers who were primary caregivers to a schizophrenic son were interviewed using the Causal Dimension Scale and the Multiscore Depression Inventory. Twenty-nine mothers generated 50 causal explanations for their son's schizophrenia. The most frequently cited causal category was physiological/biological factors. Guilt was associated with causal explanations characterized as internal, whereas depression was unrelated to causal dimensions. The findings support the need to assess mothers' causal explanations for their son's schizophrenia and to research the health consequences of causal explanations.

Adult↗

PubMed1994

Nonreentrant supraventricular tachycardia due to simultaneous conduction over fast and slow AV node pathways: successful treatment with radiofrequency ablation.

A 55-year-old woman with frequent problematic supraventricular tachycardia is presented. The tachycardia was irregular with predominantly normal QRS morphology and was refractory to multiple antiarrhythmic drugs. At electrophysiology study, the tachycardia was inducible with atrial or ventricular extrastimuli and dual pathways were observed. In contrast to the situation usually seen with dual atrioventricular node physiology, the slow pathway had a longer effective refractory period than the fast pathway and reentrant tachycardia was not induced. Simultaneous conduction over the fast and slow pathways during sinus rhythm was shown to be the mechanism for clinical tachycardia. The tachycardia was successfully treated using radiofrequency ablation of the slow pathway.

Cardiac Pacing, Artificial↗

PubMed1994

Bretylium decreases and verapamil increases defibrillation threshold in pigs.

BACKGROUND: Patients with ischemic heart disease may require antianginal and/or antiarrhythmic regimes. These patients may also be candidates for implantable defibrillators. The effects of antiarrhythmics, such as bretylium, or calcium antagonists, such as verapamil, nifedipine, or diltiazem on internal defibrillation efficacy have been inconsistent or are unknown. METHODS AND RESULTS: The effects of bretylium and verapamil on the energy requirements for ventricular defibrillation threshold (DFT) were determined in 92 open-chest anesthetized pigs. Triplicate DFTs were determined before and after intravenous administration of saline or one of four doses of verapamil, or saline or one of three doses of bretylium, in a balanced random order. Bretylium elicited a dose dependent reduction of DFT (F = 2.72 at 3 degrees and 36 degrees of freedom). DFT was significantly reduced with the highest dose of bretylium, (from 5.9 +/- 0.6 J to 4.7 +/- 0.6 J, mean +/- S.E.M.; P < 0.01). However, cardiac massage was sometimes needed at this dose due to low blood pressure immediately after defibrillation. In contrast, there was a positive correlation between DFT and serum verapamil concentration (r = 0.54, P < 0.001). The highest dose of verapamil significantly increased DFT (from 6.3 +/- 0.6 J to 8.2 +/- 1.1 J; P < 0.05), at a serum verapamil concentration of 86.6 +/- 6.8 ng/mL. CONCLUSIONS: These data indicate that bretylium decreases while verapamil increases the minimum energy requirement for internal defibrillation. Caution is warranted in patients who may be hemodynamically comprised and may be candidates for bretylium therapy or in patients who have marginal DFT value who might be candidates for verapamil therapy.

Animals↗

PubMed1994

Experience with two different nonthoracotomy systems for implantable defibrillator in 170 patients.

Implantation of a nonthoracotomy system (Medtronic PCD or CPI Endotak) was attempted in 170 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) not requiring concomitant cardiac surgery. A nonthoracotomy system could be successfully implanted in 95 of the 115 patients with the PCD system and 49 of 55 patients receiving the Endotak lead system. In 26 patients with failed nonthoracotomy system because of defibrillation threshold (DFT) > 25 joules (J), an epicardial system was implanted at the same setting. Patients receiving the two lead systems were comparable with regard to age, sex, and ejection fraction. However, since the PCD system offers tiered therapy multiprogrammable options, all attempts were made to implant this lead system in patients with VT that could be pace terminated. Mean DFT (15 +/- 4.7 vs 17 +/- 4.6 J; P = 0.03) and implant time (2.5 +/- 0.6 vs 3.3 +/- 0.7 hours; P = 0.02) were less with the Endotak lead system. There was no perioperative mortality. During a mean follow-up of 20 +/- 4 months, there were eight instances of lead dislodgment in patients receiving the PCD system. There were four nonsudden cardiac deaths and one sudden death in the Endotak group and three nonsudden deaths in the PCD group. Sudden cardiac death and total survival using the intention-to-treat analysis during this follow-up period were 99% and 95%, respectively. In conclusion, successful implantation, perioperative mortality, and survival rate are comparable with both lead systems; however, incorporating two defibrillating electrodes in one lead minimizes lead dislodgment and reduces implant time.

Anti-Arrhythmia Agents↗

PubMed1994

Ventricular fibrillation and polymorphic ventricular tachycardia with critical coronary artery stenosis: does bypass surgery suffice?

INTRODUCTION: Previous studies have suggested that coronary artery bypass surgery is sufficient to prevent recurrence of sudden death in patients with critical coronary artery stenosis presenting with ventricular fibrillation or polymorphic ventricular tachycardia. We present our experience in patients with one or more episodes of sudden death associated with documented ventricular fibrillation or polymorphic ventricular tachycardia and severe operable coronary artery disease who underwent defibrillator implant at the time of bypass surgery. METHODS AND RESULTS: Fifty-eight consecutive patients (age 63 +/- 8 years) were included in this study. Eighteen of the 58 patients had no evidence of previous myocardial infarction. The mean ejection fraction was 37 +/- 13%. All patients underwent electrophysiologic study before and after revascularization. At the time of first defibrillator discharge, each patient was reevaluated to exclude the presence of ischemia. The benefits of defibrillator implant were estimated comparing the projected survival based upon defibrillator discharge preceded by syncope or presyncope with survival curves generated including total death and sudden plus cardiac death. After a mean follow-up of 4.6 +/- 2 years, 22 patients received appropriate shocks preceded by syncope or presyncope, and an additional 19 patients received asymptomatic shocks. At 4 years, survival free of total death was 71.2%, and the projected survival was 58.8% (P < 0.05). Multivariate analysis showed that ejection fraction lower than 30% and induction of arrhythmia with one or two extrastimuli (S2, S3) were independent predictors for defibrillator discharge. None of the remaining variables including age, gender, number of bypasses, history of myocardial infarction, and type of arrhythmias induced were predictive for death and occurrence of shocks. CONCLUSIONS: In patients with ventricular fibrillation and polymorphic ventricular tachycardia, bypass surgery does not protect from recurrence of life-threatening arrhythmias, and, as in our population, defibrillator implant may have significant impact on survival.

Adult↗

PubMed1994

Shortening of fast pathway refractoriness after slow pathway ablation. Effects of autonomic blockade.

BACKGROUND: Shortening of the anterograde effective refractory period (ERP) of the fast pathway has been reported after radiofrequency ablation of the slow pathway. We hypothesized that ERP shortening may be related to autonomic changes, possibly catecholamine release, as a result of ablation. METHODS AND RESULTS: To test this, 10 consecutive patients with atrioventricular node reentry undergoing slow pathway ablation were given autonomic blockade before the ablation procedure. This was achieved by atropine 0.03 mg/kg and propranolol 0.15 mg/kg IV supplemented by half the initial dose after ablation and before the final study. A control group of 10 patients underwent the protocol without autonomic blockade. Before ablation, autonomic blockade did not alter the ERP of either the fast pathway (295 +/- 22 versus 298 +/- 26 milliseconds) or the slow pathway (264 +/- 36 versus 269 +/- 38 milliseconds). Autonomic blockade obscured dual pathway physiology in 2 patients and brought it out in another 2 without dual pathway physiology initially. Slow pathway ablation shortened the ERP of the fast pathway for the group as a whole (331.5 +/- 54 versus 305.5 +/- 60 milliseconds, mean +/- SD, n = 20, P < .04). There was no difference in degree of ERP shortening in control patients (23.5 +/- 58 milliseconds) or autonomic blockade patients (25.5 +/- 52 milliseconds). CONCLUSIONS: These data suggest that shortening of the ERP of the fast pathway after slow pathway ablation is not mediated by autonomic changes.

Adult↗

PubMed1993

Effects of thrombolysis and atenolol or metoprolol on the signal-averaged electrocardiogram after acute myocardial infarction. Late Potentials Italian Study (LAPIS).

Late potentials (LPs) detected on the signal-averaged (SA) electrocardiogram (ECG) predict arrhythmic events after acute myocardial infarction (AMI). The effect of thrombolysis on the incidence of LPs after AMI is controversial and its impact on subsequent arrhythmic events is not known. Moreover, the effects of beta blockers on the SAECG have not been studied. Six hundred eighteen patients with AMI were studied; thrombolysis was given to 228 (37%). In comparison with patients treated conventionally, those receiving thrombolysis were significantly younger and more frequently male, had higher peak values of creatine kinase, a lower prevalence of non-Q-wave AMI, and a higher incidence of ventricular fibrillation in the acute phase, and more frequently received beta blockers. An SAECG obtained 6 to 8 days after AMI showed LPs in 24% of patients receiving and in 25% not receiving thrombolysis (p = NS). On admission, intravenous beta blockers were administered to 110 patients (18%); those receiving beta blockers were younger, had lower peak values of creatine kinase and more frequently received thrombolysis. LPs were less frequently found in patients treated than in those not treated with beta blockers (15 vs 27%; p = 0.007); however, this effect was found only in those with an ejection fraction > or = 40%. Independent predictors of LPs by multivariate analysis were an ejection fraction < 40% (p = 0.007), ventricular fibrillation in the acute phase (p = 0.02), and absence of beta-blocking therapy (p = 0.03). During a mean follow-up of 12 +/- 7 months, there were 39 cardiac deaths (6%), 13 of which were sudden (2%), and 9 sustained ventricular tachycardias.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

[The spontaneous rupture of a hepatocarcinoma. A rare cause of hemoperitoneum].

The paper reports four cases of spontaneous rupture of hepatocarcinoma which were brought to the authors' attention together with the resulting hemoperitoneum. Following a short review of the literature, the authors focus on the relations between hepatocarcinoma and liver cirrhosis, on the causes which lead to the rupture of hepatocarcinoma and on its diagnosis, underlining the importance of abdominal scan with ultrasonic-guided needle biopsy. The paper stresses that, where the patient's general and local conditions allow, surgery should take the form of typical or atypical hepatic resection, and affirms that ligature of the hepatic artery associated with local hemostatic measures loads to a high percentage of early peri- or postoperative mortality, as well encouraging the early recurrence of hemorrhage.

Aged↗

PubMed1993

Initiation of atrial fibrillation in the Wolff-Parkinson-White syndrome: the importance of the accessory pathway.

Atrial fibrillation in the Wolff-Parkinson-White syndrome may be related to microreentry in the accessory pathway. If such is the case, catheter ablation of the accessory pathway should eliminate atrial fibrillation. Among 95 patients undergoing catheter ablation, 20 had atrial fibrillation during standard electrophysiologic study (atrial vulnerability) before ablation. There were 16 women and four men with a mean age of 32 years. Before ablation six patients required electrical cardioversion. Thirty minutes after ablation, 11 continued to have inducible atrial fibrillation. Atrial fibrillation terminated spontaneously in every patient after ablation. A control group of 20 patients with accessory pathway ablation had no inducible atrial fibrillation before or after ablation. Catheter ablation had no effect on atrial properties including functional refractory period (227 +/- 37 vs 215 +/- 29 msec before versus after ablation, mean +/- SD) or wavelength (7.4 +/- 3.2 vs 7.2 +/- 2.7 before versus after ablation). These data suggest that an intact accessory pathway is not necessary for initiation of atrial fibrillation in most patients with Wolff-Parkinson-White syndrome. A rapid ventricular response over the accessory pathway may facilitate the perpetuation of atrial fibrillation in persons prone to this arrhythmia.

Adult↗

PubMed1993

Effects of flecainide on defibrillation threshold in pigs.

Flecainide has been reported to decrease defibrillation efficacy in pentobarbital-anesthetized dogs. Conversely, flecainide did not alter defibrillation energy requirements in halothane-anesthetized pigs. We wished to determine whether these discrepancies were related to defibrillation technique, interaction with the anesthetic regimen, or animal species. The effects of three doses of flecainide on defibrillation threshold (DFT) were determined using single- and sequential-pulse shocks in halothane-anesthetized open-chest pigs. Triplicate DFTs were obtained before and after three doses of flecainide (n = 34) or saline (n = 13) infusion. Similarly, the effects of the highest dose of flecainide were determined using barbiturate-anesthetized animals (n = 10). Flecainide did not alter DFT at any dose with either the single-pulse shock (control 17.7 +/- 2.1 J, highest dose of flecainide 19.1 +/- 3.2 J, p = NS) or sequential-pulse shock (control 9.2 +/- 1.0 J, highest dose of flecainide 8.4 +/- 1.4 J, p = NS) when halothane anesthesia was used. Similar results were obtained using barbiturate anesthesia either with sequential (control 8.7 +/- 0.9 vs. 8.2 +/- 0.6 J, p = NS) or single shocks (control 13.2 +/- 0.8 vs. 13.7 +/- 1.0 J, p = NS). Flecainide did not alter DFT in our model, regardless of defibrillation technique or anesthetic regimen.

Animals↗

PubMed1993

Ethanol increases defibrillation threshold in pigs.

Alcohol ingestion has been associated with cardiac arrhythmias and may initiate fibrillation in patients with automatic defibrillators. The effect of alcohol on defibrillation efficacy is unknown. To assess the acute effects of alcohol on defibrillation efficacy, triplicate defibrillation thresholds (DFTs) were determined before and after intravenous administration of 25% ethanol. Fifty-two pigs were randomized into four groups: (1) control, 6 mL/kg of saline over 10 minutes (n = 12); (2) low dose, 6 mL/kg of 25% ethanol over 10 minutes (n = 12); (3) mid dose, 0.45 mL/kg per minute for 30 minutes followed by 0.045 mL/kg per minute for 45 minutes (n = 12); and (4) high dose, 0.6 mL/kg per minute for 30 minutes followed by 0.06 mL/kg per minute for 45 minutes (n = 16). Three coil defibrillating electrodes (Medtronic 6888) were sutured to the epicardium of the right and left ventricles for defibrillation shocks. Ventricular fibrillation was induced using alternating current and after 10 seconds of fibrillation, the minimum energy for defibrillation was established using sequential pulse defibrillation. Triplicate determinations were obtained before and after saline or ethanol infusion. Alcohol elevated DFT in a dose related manner. Control and low dose groups thresholds were unchanged, but the mid dose approached statistical significance (6.8 +/- 0.7 vs 7.6 +/- 0.9 J, 0.05 < P < 0.1) and the high dose was significantly elevated (8.5 +/- 0.7 vs 11.2 +/- 1.1 J, P < 0.01). Ventricular effective refractory periods and cycle lengths between fibrillatory waves did not differ before and after the high dose ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗