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Biomedical subjects

M Chimienti

Publications and source records attributed to M Chimienti.

At least 19 recordsLinked to original sources
PubMed1992

Comparison of isoproterenol and exercise tests in asymptomatic subjects with Wolff-Parkinson-White syndrome.

In order to evaluate the effects of increases of sympathetic tone in ventricular response during atrial fibrillation and in the relationship between the accessory pathway effective refractory period (ERP) and ventricular rate during atrial fibrillation, 20 male subjects, aged 19 +/- 6 years, were studied electrophysiologically in basal conditions, after isoproterenol infusion (2-4 micrograms/min) and during submaximal bicycle exercise test, at a constant workload equal to that which increases the sinus rate to the same extent (140 beats/min) induced by isoproterenol infusion. Accessory pathway ERP was evaluated at the same driven rate (150 beats/min) in both instances. In the control study as during both tests atrial fibrillation paroxysms were induced by burst stimulation. In control conditions the rate increase from 100 to 150 beats/min induced a reduction of accessory pathway ERP from 266 +/- 27 msec to 244 +/- 22 msec (P less than 0.005). At the same driven rate of 150 beats/min, isoproterenol infusion and exercise test induced a more marked shortening of accessory pathway ERP to 211 +/- 28 msec (P less than 0.005) and to 214 +/- 29 msec (P less than 0.005), respectively. Atrial fibrillation paroxysms lasting more than 10 seconds were induced in 20/20 cases in the control study, in 15/20 during isoproterenol infusion and in 13/19 cases during exercise test. The shortest cycle length during atrial fibrillation was reduced from a basal value of 253 +/- 72 msec to 204 +/- 27 msec (P less than 0.05) during isoproterenol infusion and to 236 +/- 32 msec (NS) during exercise test.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Hyperventilation and ergonovine tests in Prinzmetal's variant angina pectoris in men.

Hyperventilation and ergonovine tests were carried out in a group of 30 patients with variant angina to assess the sensitivity of the 2 tests and to correlate the response with spontaneous disease activity. Hyperventilation produced a positive response in 83% (25 of 30) and ergonovine in 93% (28 of 30) of the patients. After hyperventilation 22 of 25 showed ST-segment elevation, 2 ST depression and 1 T-wave pseudonormalization; after ergonovine ST-segment elevation developed in 23 patients, ST depression in 4 and T-wave pseudonormalization in 1. In all cases the electrocardiographic changes occurred in the same leads as during the spontaneous attacks. The incidence of chest pain and ventricular arrhythmias was similar during both tests; spontaneous remission of ischemia, however, was more frequent (48 vs 14%) after hyperventilation than after ergonovine. Acute ischemia developed at a mean of 218 +/- 112 seconds after the end of hyperventilation in 19 of 25 positive tests; at that time double product was not significantly different from basal values. The sensitivity of hyperventilation was similar (95 vs 100%) to ergonovine in the patients with greater than or equal to 1 daily attack, while in those with less than 1 daily attack the sensitivity of hyperventilation decreased to 55% compared to 77% with ergonovine. Thus, in variant angina the sensitivity of both tests correlates with disease activity. Hyperventilation is a safe provocative test with a sensitivity similar to ergonovine in patients with active disease; however, in patients with sporadic attacks hyperventilation has a lower sensitivity than ergonovine and therefore a limited diagnostic value.

Adult↗
PubMed1989

Time-related decrease in sensitivity to ergonovine in patients with variant angina.

Eighteen patients with variant angina, a positive ergonovine test, and a favorable response to calcium antagonists were studied by serial ergonovine tests and Holter monitoring to assess the long-term changes in response to ergonovine and the relationship with the spontaneous activity of the disease. The number of patients with a positive test decreased from 18 of 18 in the acute phase to 12 of 18 (66%) at 3 months, 10 of 17 (59%) at 6 months, and five of 17 (29%) at 12 months. The mean dose level of ergonovine associated with a positive response and the percentage of positive tests with ST segment depression increased progressively during follow-up. The results of the ergonovine test were well correlated with the spontaneous activity of the disease in 94%, 83%, 76%, and 71% of the patients at initial observation and at 3, 6 and 12 months, respectively. Thus in patients with variant angina and a favorable response to calcium antagonists, a time-related decrease in sensitivity to ergonovine develops during follow-up. In most patients the response to ergonovine is well correlated with the spontaneous activity of the disease; thus the ergonovine test may be a useful tool in the assessment of the natural evolution of vasospastic angina.

Adult↗
PubMed1989

Electrophysiologic and clinical effects of oral encainide in paroxysmal atrioventricular node reentrant tachycardia.

The electrophysiologic effects of oral encainide (75 to 150 mg daily) were evaluated in 14 patients (6 male and 8 female, aged 49 +/- 9 years) with atrioventricular (AV) node reentrant tachycardia of the slow-fast type. The patients were studied in control conditions and after 2 to 12 days of treatment. Encainide increased the AH interval from 67 +/- 10 to 82 +/- 23 ms (p less than 0.02). Anterograde Wenckebach cycle length was increased in three patients, reduced in four, unchanged in one; it was not measurable in the remaining patients because tachycardia was induced. Retrograde Wenckebach periodicity increased from 307 +/- 71 to 401 +/- 92 ms (p less than 0.005) in all nine patients in whom it was measurable; complete retrograde block was observed in one patient. At the control study, tachycardia was induced in all patients, with a mean cycle length of 341 +/- 50 ms; after encainide, tachycardia was inducible in only 1 patient, with an increase in cycle length from 270 to 320 ms; in the other patients, tachycardia was not inducible because of a lack of retrograde (11 patients) or anterograde (2 patients) conduction. The mean plasma concentrations of encainide and its metabolites O-demethyl-encainide and 3-methoxy-O-demethyl-encainide measured in 13 patients during the repeat study were 161 +/- 304, 128 +/- 100 and 95 +/- 85 ng/ml, respectively; three poor metabolizers who presented a high concentration of the parent compound were observed in this series. All patients were discharged on encainide at a mean daily dose of 112 +/- 39 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1989

[An electrophysiologic and electropharmacological study of functional properties of the bundle of Kent in Wolff-Parkinson-White syndrome].

The aim of this report is to attempt a definition of functional properties of Kent bundle on the basis of electrophysiologic and electropharmacologic data obtained from 89 cases of Wolff-Parkinson-White syndrome selected among a total number of 114 consecutive cases of WPW syndrome that underwent electrophysiologic intracavitary study. In 36 cases anterograde (ant) and retrograde (retr) effective refractory period (ERP) of accessory pathway were evaluated with premature (atrial and ventricular) stimulation at the same driven cycle length. The ant-ERP was longer than retr-ERP in 28/36 patients, shorter in 5 and equal in 2. This strong discrepancy between ant- and retr- ERP suggests an important role of "impedance mismatch" in the activation of ventricular (or atrial) muscle through an anomalous muscular bundle. In 11 cases an intermittent pattern of ventricular preexcitation was observed; in all these patients an anterograde supernormal conduction through the accessory pathway was observed. This aspect could be related to the activation of ventricular muscle, beyond Kent bundle, in its supernormal phase of excitability, suggesting the critical role played by ventricular activation for the appearance of preexcitation. Isoproterenol, injected in 11 cases (1 among them with intermittent ventricular preexcitation in basal conditions), produced a reduction of ant-ERP in all these cases, in spite of its well known poor effect on refractoriness of myocardial fibers. Ajmaline, injected in 32 patients, was able to block ventricular preexcitation in 81% of the cases, in spite of its poor effect on refractoriness of normal tissues. It is very likely that the disappearance of ventricular preexcitation is in this instance expression of lack of ventricular excitation (distal to Kent bundle) consequent to a drug-induced reduction of membrane responsiveness of ventricular cells. In conclusion, all these aspects strongly suggest that the appearance of ventricular (or atrial) preexcitation could be related to the activation of ventricular (or atrial) muscle distal to Kent bundle, rather than to conduction through the Kent bundle itself.

Ajmaline↗
PubMed1988

Comparison of the effectiveness of dihydroquinidine and quinidine on ventricular ectopy after acute and chronic administration.

The aim of this study was to compare the pharmacokinetics and antiarrhythmic activity of dihydroquinidine and quinidine in 14 patients (11 men, 3 women, aged 28 to 67 years) with heart disease and chronic, stable, high-frequency premature ventricular beats (PVB) (greater than 100/hr). A randomized, double-blind, crossover, placebo-controlled protocol was utilized. During Holter monitoring the patients were given either dihydroquinidine or quinidine as the gluconates in an oral solution (600 mg); blood samples were taken 0.5, 1, 1.5, 2, 4, 6, 8, and 12 hours later. The patients were then assigned to three successive treatment periods of 7 days each: dihydroquinidine HCl (900 mg/day), quinidine polygalacturonate (1,650 mg/day), or placebo. At the end of each period 24-hour Holter monitoring was carried out and a blood sample was taken for determination of drug concentration. By comparing the area under the curves dihydroquinidine was 59% as available as quinidine; rates of absorption and elimination were similar. Mean peak blood levels of dihydroquinidine and quinidine were 1.06 +/- 0.34 and 2.15 +/- 0.96 micrograms/ml, respectively. After dihydroquinidine, eight patients had a positive response (greater than 50% reduction in PVB frequency), while seven patients responded to quinidine. During maintenance treatment both dihydroquinidine (233 +/- 330) and quinidine (234 +/- 311) reduced the mean PVB frequency per hour compared to placebo (690 +/- 569). Nine patients (64%) on dihydroquinidine and eight (57%) on quinidine had greater than 70% decrease in mean PVB frequency per hour. Steady-state peak plasma concentrations of dihydroquinidine and quinidine were 1.10 +/- 0.41 and 2.24 +/- 1.13 micrograms/ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Spontaneous remission of variant angina documented by Holter monitoring and ergonovine testing in patients treated with calcium antagonists.

Twenty-four patients with Prinzmetal's variant angina showing a favorable initial response to calcium antagonist treatment were studied to assess the evolution of the disease and the frequency and time course of spontaneous remission. At 3, 6 and 12 months from the acute phase, patients underwent in-hospital control studies, with 48-hour Holter monitoring and ergonovine testing carried out during treatment and after its interruption. During calcium antagonist therapy complete protection from spontaneous attacks was documented in 22 of 24 patients at 3 months, in 19 of 21 at 6 months and in all 21 at 12 months; ergonovine test results were negative in 16 of 23 patients at 3 months, in 16 of 20 at 6 months and in all 20 studied at 12 months. After stopping treatment spontaneous attacks did not reappear in 7 of 24 patients (29%), 14 of 21 (66%) and 16 of 21 (76%) at 3, 6 and 12 months respectively, while the ergonovine test response remained negative in 6 of 21 (28%), 7 of 18 (39%) and 13 of 20 (65%) of the patients controlled at 3, 6 and 12 months. Thus, complete remission of angina documented by both Holter recording and ergonovine testing occurred in 5 of 24 patients (21%) at 3 months, in 7 of 21 (33%) at 6 months and in 12 of 21 (57%) at 12 months. Patients with remission of angina had a shorter duration of symptoms and more often showed normal or not critically diseased coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1987

Electrophysiologic and clinical effects of intravenous and oral encainide in patients with Wolff-Parkinson-White syndrome and paroxysmal atrial fibrillation.

The electrophysiologic effects of encainide were studied in 10 patients with Wolff-Parkinson-White syndrome after intravenous (1 mg kg-1 in 60 minutes) and oral administration of two dose regimens (75 and 150 mg daily). Under control conditions atrial fibrillation (AF) with a rapid ventricular response was induced in all patients and atrioventricular reciprocating tachycardia (AVRT) in 9 patients. After intravenous encainide AF was no longer induced in 3/9 patients; in 3 of the remaining the accessory pathway (AP) was totally blocked and in the others the shortest RR interval increased from 213 +/- 6 to 297 +/- 91 ms and the mean RR interval from 293 +/- 39 to 362 +/- 79 ms. The lower dose of oral encainide prolonged the shortest RR interval from 206 +/- 24 to 273 +/- 64 ms and the mean RR interval from 280 +/- 48 to 368 +/- 52 ms in 6 patients; in 2 cases no preexcited beats were recorded and in 1 AF was not inducible. After the higher dose of oral encainide AF was still inducible in 7/8 cases; in 3 the AP was blocked and in the others the shortest and mean RR intervals increased from 202 +/- 30 to 280 +/- 24 ms and from 276 +/- 59 to 436 +/- 80 ms, respectively. After intravenous encainide antegrade conduction over the AP was blocked in 4/9 patients and the antegrade effective refractory period (ERP) was prolonged in another 4. Oral encainide blocked AP conduction in 4 cases and prolonged ERP considerably in the others.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1986

Ventricular tachycardia in post-myocardial infarction patients. Preoperative and intraoperative mapping.

Ventricular tachycardia has become a relatively common complication of myocardial infarction and often is an important therapeutic problem, as it is recurrent and life-threatening. Here we report a group of 36 patients with ventricular tachycardia occurring 13 days to 30 years after a myocardial infarction. All patients were resistant to medical treatment and 34 of the 36 patients had had at least one cardiac arrest. All were candidates for surgery for their arrhythmia. The study protocol included prolonged ECG monitoring, a preoperative electrophysiological study with catheter mapping and intraoperative epicardial and endocardial mapping. A total of 52 different tachycardias were mapped in 36 patients. The procedure was facilitated by an automatic mapping device, that allowed the acquisition of 35 simultaneous signals, so that even pleomorphic ventricular tachycardias could be mapped. The information obtained from both preoperative and intraoperative maps guided surgery and restricted the extent of the surgical damage.

Adult↗
PubMed1986

Ventricular tachycardia in post-myocardial infarction patients. Results of surgical therapy.

This report addresses the problems related to surgical treatment of post-infarction ventricular tachycardia (VT) and is based on a 5 year experience of 36 consecutive patients. In every case the arrhythmia was unresponsive to pharmacological therapy. All patients were operated on after the completion of a diagnostic protocol including preoperative endocardial, intra-operative epi-endocardial mapping, the latter performed automatically when possible. Surgical techniques were: classical Guiraudon's encircling endocardial ventriculotomy (EEV); partial EEV, endocardial resection (ER); cryoablation or a combination of these procedures. The in-hospital mortality (30 days) was 8.3% (3 patients). During the follow-up period (1-68 months), 3 patients (9%) died of cardiac but not VT related causes. Of the survivors, 92% are VT-free. We consider electrophysiologically guided surgery a safe and reliable method for the treatment of post-infarction VT and suggest its more extensive use. We stress the importance of automatic mapping in pleomorphic and non-sustained VT, and the necessity of tailoring the surgical technique to the characteristics of each case.

Cardiac Pacing, Artificial↗
PubMed1986

Ventricular arrhythmias during acute myocardial ischaemia in man. The role and significance of R-ST-T alternans and the prevention of ischaemic sudden death by medical treatment.

Malignant ventricular arrhythmias appearing during acute myocardial ischaemia, are the most frequent mechanism of sudden death. ST-T alternans is the result of an intraischaemic conduction delay and is frequently associated with those potentially lethal arrhythmias. In fact, such a phenomenon was seen in 35% of 46/86 patients with Prinzmetal's variant angina who showed ventricular arrhythmias during ischaemia, while it was never observed in the remaining 40 patients without arrhythmias during ischaemia. Therefore ST-segment alternans should be considered a reliable marker of the possible occurrence of ventricular arrhythmias during myocardial ischaemia. ST-T-segment alternans is associated with R alternans, as clearly demonstrated by thoracic maps, and this phenomenon is due to a 2:1 intraischaemic block. The patients with Prinzmetal's variant angina who present ventricular arrhythmias during ischaemia, show a more prominent increase of the positive area of the QRS (411.75 +/- 102.5 vs 294.05 +/- 80.3 mu volts ms), that is, a more relevant intraischaemic conduction delay. The effects of different pretreatments (lidocaine, propranolol and diltiazem) on arrhythmias related to vasospastic myocardial ischaemia induced by ergonovine maleate, were evaluated in four patients with Prinzmetal's variant angina. As in experimental observations, neither a 'pure' antiarrhythmic agent like lidocaine, nor a betablocking agent like propranolol, prevented acute ischaemic ventricular arrhythmias. Only the calcium antagonist, diltiazem, seemed to prevent such arrhythmias. However, these findings necessitate further confirmation.

Angina Pectoris, Variant↗
PubMed1986

When are arrhythmias and conduction disturbances markers of myocardial ischemia at rest?

Myocardial ischemia, particularly when transmural as in variant angina pectoris, may be associated with ventricular tachycardia, ventricular fibrillation and paroxysmal atrioventricular block (15%). Syncope (7%) and sudden death (3%) due to these malignant arrhythmias are sometimes a unique marker of myocardial ischemia. Two-hundred fifty-four patients (220 males and 34 females), aged 5 +/- 9 years with transmural myocardial ischemia related to coronary artery spasm, were studied. Particular attention was paid to the role of syncopal attacks as unique clinical manifestation of silent ischemia. Patients examined were divided into 3 Groups. Group 1 includes 5/254 (2%) patients with atrial fibrillation during acute ischemia. Group 2 was divided into four subgroups: subgroup A includes 17/254 (7%) patients with syncopal attacks due to malignant arrhythmias (ventricular tachycardia and advanced A-V block); subgroup B, 15/254 (6%) patients with documented malignant arrhythmias, without syncopal attacks; subgroup C, 7/254 (3%) with ventricular fibrillation during acute ischemia and subgroup D, 18/254 (7%) patients with history of syncopal attacks without documented arrhythmias during hospital observation. Group 3 includes 17/254 (7%) patients with left anterior hemiblock in basal condition, 7/254 (3%) patients with left anterior hemiblock and one left posterior hemiblock during acute ischemia and one patient with right bundle branch block during acute ischemia. Syncopal symptoms are present in many of these cases of angina pectoris; paroxysmal A-V block is documented in nearly half of the cases with syncope (65%); ventricular tachycardia is frequently demonstrated during ischemia but leads to syncope in only a few cases; patients with syncope do not present specific clinical features.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris, Variant↗