Biomedical subjects

R De Ponti

Publications and source records attributed to R De Ponti.

9 recordsLinked to original sources

PubMed1996

[Transcatheter radiofrequency bundle branch ablation in bundle branch reentry ventricular tachycardia: report of a case].

Two patients with branch to branch ventricular tachycardia (BBVT) are reported: successful radiofrequency catheter ablation of BBVT was performed in both, delivering energy distally to the point where the maximum amplitude of His deflection occurred, so that a wide ventricular deflection was obtained without any atrial electrogram. No significant conduction delay appeared but a right bundle branch block. HV intervals during BBVT resulted equal or longer than in sinus rhythm: whether this was secondary to anatomical or functional variations or to the possibility that the His bundle may be "bystander" in BBVT, is discussed.

Adult↗

PubMed1994

Spontaneous incessant AV reentrant tachycardia related to left bundle branch block and concealed left-sided accessory AV pathway.

Three patients in whom permanent AV reentrant tachycardia became the clinical manifestation of Wolff-Parkinson-White syndrome are described. The substrate for the arrhythmia was created by coexistence of a concealed left-sided accessory pathway and an ipsilateral bundle branch block. Pharmacologic therapy in all three patients failed to control the tachycardia, which in two cases led to severe left ventricular failure. After successful radiofrequency ablation of the accessory pathway (in two) or AV junction (in one), left ventricular function gradually returned to normal.

Bundle-Branch Block↗

PubMed1994

[Radiofrequency catheter ablation in patients with Mahaim-type slow-conduction accessory right atrioventricular pathway].

In some cases undergoing radiofrequency catheter ablation (RFCA) of accessory pathway (AP), a Mahaim-like right-sided atrioventricular AP (M-AP) showing slow and decremental conduction is observed. Among 200 consecutive patients referred to our Institution up to September 1993 for arrhythmias related to an AP and undergoing RFCA, 8 patients (6 males, 2 females; mean age 24 +/- 8 years, range 8-35) showed a M-AP. Seven out of 8 patients have been complaining episodes of palpitation for 13 +/- 7 years (range 1-20), while 1 subject was an asymptomatic young athlete. In 2/8 patients an Ebstein disease (Eb) was present and they had previously undergone right-sided Kent bundle (Kb) ablation elsewhere. During sinus rhythm, QRS was normal in 1 patient, while it showed ventricular preexcitation due to right-sided Kb in 3 patients and right bundle branch block in another 4 patients. A left bundle branch block morphology (LBBBM) reentrant tachycardia (RT) was observed in 7 patients (in 1, only after RFCA of a right-sided Kb); 3 showed also orthodromic RT. In the asymptomatic young athlete, a preexcitation atrial fibrillation with very rapid ventricular response was inducible. All patients underwent diagnostic electrophysiologic (EP) study and RFCA in the same session. In 2/8 patients M-AP was manifest only after right-sided Kb RFCA. In all patients, associated EP abnormalities were noted: in 5/8 patients a dual A-V node pathway was present and in 5/8 patients 6 right-sided Kbs were associated. Patients have been divided in 3 groups, according to the mechanism involving the M-AP in the RT. In the 2 Group I patients showing also Eb, antidromic LBBBM RT and orthodromic RT involving the M-AP anterogradely and retrogradely, respectively, were observed; both arrhythmias were abolished by ablating the M-AP. The 3 Group II patients showed only antidromic LBBBM RT, involving a fast A-V node pathway retrogradely; also in these patients, the M-AP was the target of RFCA. This was performed only in 1 patient, in whom A-V node RT was also observed and ablated after RFCA of M-AP; as to the other 2 patients, in 1 the ablation of M-AP was not considered mandatory, since it was responsible for inducible not sustained LBBBM RT observed only after RFCA of a Kb in the same EP session, while in the other it was not possible because of a prolonged traumatic conduction block through the M-AP.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1994

[Atrioventricular reciprocating tachycardia with QRS type left branch block in patients undergoing radiofrequency catheter ablation: analysis of the substrate and mechanism of tachycardia].

BACKGROUND: Among patients (pts) with atrioventricular accessory pathway (AP), some cases show wide complex arrhythmias with different QRS morphology. In a subset of these pts, an atrioventricular reentrant tachycardia with left bundle branch block morphology (LBBBM-AVRT) is observed. The aim of this study is: 1) to identify the substrate and the reentrant mechanism underlying the LBBBM-AVRT in pts undergoing radiofrequency catheter ablation (RFCA) of AP; 2) to report the results achieved by RFCA of the identified substrate. METHODS: From May 1991 to April 1993, among the 168 pts who underwent RFCA for arrhythmias related to an AP, 12 (7.1%) (8M, 4F, mean age 35 +/- 21 yrs, range 8-65) showed LBBBM-AVRT, alone or associated with other arrhythmias. Pts, in whom LBBBM was rate-related during orthodromic AVRT, were excluded from this study. During sinus rhythm, QRS complex was normal in 1 pt, while ventricular preexcitation due to a right-sided Kent bundle (KB) was present in 4 pts; among the other pts without preexcitation, 3 showed left bundle branch block (LBBB) and 4 right bundle branch block. In 2 pts, an Ebstein disease was present, while dilated cardiomyopathy was observed in another. The LBBBM-AVRT was iterative in 3 pts and in 6 pts it was the only arrhythmia observed; the mean tachycardia cycle length was 341 +/- 49 msec (range 250-428). In 1 pt, the LBBBM-AVRT was induced only after successful RFCA of a right-sided AP, responsible for orthodromic AVRT. All pts underwent diagnostic electrophysiologic study and RFCA during the same session. RESULTS: In 6/12 pts one or more KBs were observed, while in the remaining 6 an atrioventricular or atriofascicular "Mahaim like" bundle (MB) was present; the patient population was divided into 4 groups on the basis of the substrate and the reentrant mechanism responsible for LBBBM-AVRT. In Group 1, 3 pts were included: the LBBBM-AVRT was an orthodromic AVRT involving the nodal conduction antegradely (showing LBBB also during sinus rhythm) and a left-sided unidirectional KB, retrogradely. In all the 3 pts, the LBBBM-AVRT was iterative and not controlled by antiarrhythmic agents and RFCA of the KB abolished the arrhythmia. Two further pts were included in Group 2: in these pts with multiple bilateral KBs, the LBBBM-AVRT involved a right-sided KB antegradely and a left-sided one, retrogradely. In these 2 pts both KBs were successfully ablated. In 1 pt, considered in Group 3, the LBBBM-AVRT was sustained by an antidromic circuit involving a right-sided KB antegradely and the nodal conduction retrogradely; in this pt the KB was completely interrupted after two RFCA procedures. The remaining 6 pts with MB were included in Group 4: at least one associated electrophysiologic abnormality was present in all (dual A-V nodal pathway in 4/6 and a right-sided KB in 4/6); Ebstein disease was also observed in 2 of them. In 4/6 pts the LBBBM-AVRT was an antidromic tachycardia involving the nodal conduction retrogradely and the MB antegradely; in 3/4 pts the MB was ablated (along with a nodal reentrant tachycardia in 1 pt), while in the remaining pt in whom the non-sustained LBBBM-AVRT, inducible only after RFCA of a right-sided KB, had not been clinically observed, no further ablation was mandatory. In the remaining 2 pts in Group 4, the LBBBM-AVRT was due to the involvement of MB in other arrhythmias such as an AVRT due to a right-sided KB and a "slow-slow" nodal reentrant tachycardia, respectively; the LBBBM-AVRT were abolished by RFCA of these two underlying arrhythmias. All pts are asymptomatic during a 7.9 +/- 6.9 months follow-up. CONCLUSIONS: The LBBBM-AVRT is observed in a minority (7.1%) of the cases referred for RFCA of AP. (ABSTRACT TRUNCATED)

Adolescent↗

PubMed1993

[New perspectives in the ablation of ectopic atrial tachycardia and atrial flutter].

The first experiences on non-pharmacological treatment of ectopic atrial tachycardia (EAT) and common atrial flutter (AFl) were performed by surgical techniques. The surgical abolition of EAT comprised the isolation, the excision or the cryoablation of the ectopic atrial foci using electromapping guide. The AFl was treated by extensive cryoablation of the slow conduction area responsible for the macroreentrant process located in the infero-posterior part of the right atrium (RA). Transcatheter ablation with DC-shock for the treatment of EAT was proposed in 1985 but the technique did not gain wide acceptance due to its risks. The same method was utilized for the treatment of AFl since 1987. Many preliminary studies reported on the use of transcatheter ablation with radiofrequency (RF) current as an energy source since 1992 and no major complications were encountered. According with our knowledge, 81 cases of permanent or iterative EAT were treated by RF in the world with a primary success rate superior than 90%. The low rates of recurrence are reported very early (within 24-48 hours) after the procedure; recurrencies are very easy to recognise and they are successfully ablated in a second session. Cases of EAT due to an ectopic focus localized in the RA are ablated from the superior or inferior vena cava approaches and cases of EAT related to a left atrial (LA) ectopic focus by a trans-septal approach (persistent foramen ovale or atrial septum puncture). On the basis of our personal experience regarding 7 cases (4 LA and 3 RA foci) the role of unipolar leads derived from the mapping catheter appears essential to select the target for RF applications.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

[Radiofrequency transcatheter ablation of anomalous left atrioventricular pathways: the role of the transseptal approach].

BACKGROUND AND METHODS: In this study we used two different approaches in radiofrequency catheter ablation (RFCA) of the left free wall atrioventricular accessory pathway (AP): the retrograde transaortic (TAo) approach and the transseptal (TSA) one. Our aim was to evaluate the success rate and the duration of the two procedures. From May 1, 1991 to April 30, 1992, 33 pts (23 M, 10 F; mean age 38 +/- 16 years, range 14-66) with left free wall atrioventricular AP were selected among a 57 patient population, in which RFCA was performed for arrhythmias related to the AP. In 20/33 pts (61%) stable ventricular pre-excitation was present, while in 4/33 (12%) it was intermittent; in the remaining 9/33 pts (27%) only retrograde conduction through the AP was documented. In the majority of the pts (26/33) a diagnostic electrophysiologic study was performed immediately before the ablation procedure, during the same EP test. A 7 F steerable large tip catheter was used for energy delivery. In 8/33 pts, RFCA was performed by using only the TAo approach; other 7/33 pts underwent RFCA with a TSA technique after one completely unsuccessful retrograde TAo ablation and, in the remaining 18/33 pts, the TSA approach was used electively and continuously from January 1992. Overall, the TAo procedure has been carried out in 15 cases, while the TSA one in 25 cases. In the latter group, the ablation catheter was positioned against the left atrioventricular groove through a patent foramen ovale in 5/25 cases (20%), while a TSA puncture was needed in the remaining 20 cases. After successful ablation, the observation period was prolonged up to 60 min. RESULTS: Complete AP ablation was achieved in 31/33 pts (94%), while the remaining 2 pts underwent surgical cryo-ablation after unsuccessful TAo procedure. Among the three different subsets of pts, the success rate was as follows: 40% (6/15 cases) by using TAo technique, 100% (7/7 cases) by TSA after one unsuccessful attempt with the TAo technique, and 94% (17/18 cases) after single elective TSA; in the only case where the first elective TSA procedure failed, a second attempt was successful. The duration of the whole electrophysiologic test was 4.0 +/- 1.3 hours for the TAo approach vs 3.3 +/- 0.9 hours for the TSA one (p < 0.05). The mean fluoroscopy time was significantly (p < 0.05) shorter in pts who underwent elective TSA (43 +/- 27 min), than in pts who underwent only TAo approach (68 +/- 42 min) or both TAo and TSA approach (157 +/- 54 min). No complication during or after the procedure was observed in any case. CONCLUSIONS: In RFCA of left free wall atrioventricular APs, the TSA approach seems to be as safe as the TAo approach. In this preliminary experience, the success rate and the short duration of single elective TSA procedure suggest that this can be used as a first-choice approach in these pts.

Adult↗

PubMed1992

[Transcatheter radiofrequency modulation and ablation of the atrioventricular junction in supraventricular arrhythmias refractory to medical therapy].

In patients with supraventricular tachyarrhythmias refractory to medical therapy, transcatheter ablation (TA) is necessary. From January 1990, in 27 patients with nodal tachycardia and 6 with atrial fibrillation or flutter, referred to our institution for electrophysiologic evaluation, TA by radiofrequency (RF) was performed, respectively for atrioventricular (AV) junction modulation and total AV junction ablation. In all these cases, a total refractoriness to several antiarrhythmic drugs alone or in combination had been observed. The RF current, generated by the Osypka HAT 100 device, was administered through a tripolar USCI 7 F catheter. The ideal site for energy delivery was defined on the basis of a mapping, performed in the AV junction area to find out the most premature retrograde atrial activation. Local atrial activation time was evaluated during nodal tachycardia by delivering a premature ventricular extrastimulus to discover the atrial deflection from the ventricular one. In the selected area, 5 applications (range 1-12) of 20-25 W power RF energy for 5-30 s were delivered on average. A complete prevention of nodal tachycardia was achieved in 26/27 patients (96.2%). Only in 2 patients (7.4%) a total AV block was induced. The pre- and post-procedure values are as follows: AH = pre 71 +/- 18, post 113.2 +/- 53; HV = pre 46.4 +/- 8, post 48 +/- 7; anterograde Wenckebach point = pre 352 +/- 56, post 389 +/- 91; retrograde Wenckebach point = pre 338 +/- 75, post 419 +/- 61. In 13/27 cases the AH interval was normal after RF application. The retrograde conduction was worsened in all patients and totally abolished in 12/27.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

[Indications and results of transcatheter ablation and surgery in paroxysmal reentry nodal tachycardia].

In patients with nodal tachycardia refractory to medical therapy, transcatheter or surgical ablation is necessary. From January 1989 to December 1990, in 26/42 patients with nodal tachycardia, referred to our institution for electrophysiologic evaluation, transcatheter ablation by radiofrequency (20 patients) or surgical ablation by perinodal cryo (6 patients) was performed. In all these cases, a total refractoriness to several antiarrhythmic drugs alone or in association had been observed. The radiofrequency current, generated by the Osypka HAT 100 device, was administered through a tripolar USCI 7 F catheter. The ideal site for energy delivery was defined on the basis of a mapping, performed in the A-V junction area. In order to find out the most premature retrograde atrial activation, the following areas were explored: right bundle, atrial His bundle, peri-nodal region, proximal His bundle and coronary sinus ostium. Local atrial activation time was evaluated during nodal tachycardia by delivering a premature ventricular extrastimulus to discover the atrial deflection from the ventricular one. In the selected area, 5 applications (range 1-12) of 20-25 W power radiofrequency energy for 5-30 s were delivered on average. A complete prevention of nodal tachycardia was achieved in 18/20 patients (90%). Only in 2 patients a total A-V block was induced. The pre- and post-procedure values are as follows: AH: pre 71 +/- 19, post 113.6 +/- 50; HV: pre 45.5 +/- 8, post 47 +/- 6; aWP: pre 353 +/- 57, post 391 +/- 87; rWP: pre 322 +/- 58, post 411 +/- 58. In 10/18 cases the AH interval was normal after radiofrequency application.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

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↗