			Home About us Contact

Isoproterenol Infusion (isoproterenol + infusion)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Adrenergic Nervous System Influences on the Induction of Ventricular Tachycardia

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2002
Oscar A. Pellizzón M.D.
Background: Sudden cardiac death is a major cause of mortality in western countries and the ventricular tachyarrhythmias are mainly involved in this regard. The adrenergic autonomic nervous system has influences in provoking life-threatening arrhythmias, and the prevention of such arrhythmias with beta-blockers supports this viewpoint. To evaluate the effect of the adrenergic nervous system and some catecholamine-releasing stimuli on the induction of ventricular tachycardia, we decided to explore the occurrence of ventricular tachycardia in patients subjected to three consecutive tests, exercise testing, isoproterenol infusion, and mental stress. Methods: Nineteen subjects who experienced exercise test-induced ventricular tachycardia were subjected to an isoproterenol infusion and mental stress. All but one patient had cardiac disease, with 70% due to Chagas'disease. Seventeen of the 19 study subjects had normal ventricular function. Results: Exercise test-induced ventricular tachycardia was nonsustained in 17 patients and sustained in 2 cases. Isoproterenol infusion induced nonsustained ventricular tachycardia in 9 of 19 patients. Mental stress, on its own, was able to induce nonsustained ventricular tachycardia in 2 of 19 patients. Conclusions: Among patients preselected for exercise-induced ventricular tachycardia, almost half could be induced into ventricular tachycardia by isoproterenol infusion. Mental stress was a less powerful inducer of ventricular arrhythmias in this study group. A.N.E. 2002;7(4):281,288 [source]

ATP-Induced Dormant Pulmonary Veins Originating from the Carina Region After Circumferential Pulmonary Vein Isolation of Atrial Fibrillation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2010
KOJI KUMAGAI M.D., Ph.D.
Dormant Pulmonary Veins from the Carina Region.,Introduction: Elimination of transient pulmonary vein recurrences (dormant PVs) induced by an ATP injection and ablation at the PV carina region is an effective strategy for atrial fibrillation (AF) ablation. The relationship between dormant PVs and the PV carina region has not been evaluated. Methods: A total of 212 consecutive symptomatic AF patients underwent circumferential PV electrical isolation (CPVEI) with a double lasso technique. They were divided into 2 groups in a retrospective review; Group 1: those given an ATP injection during an intravenous isoproterenol infusion after the CPVEI (n = 106), and Group 2: those in which it was not given after the CPVEI (n = 106). Radiofrequency energy was applied at the earliest dormant PV activation site identified using a Lasso catheter on the CPVEI line and then PV carina region if it was ineffective. Results: After a successful PVEI, 54 patients (51%) in Group 1 had PV reconnections during an ATP injection. Acute PVEI sites were observed on the carina region within the CPVEI line in the right PVs (16%) and left PVs (10%). Dormant PVs were reisolated at the carina region in the right PVs (23%) and left PVs (26%). The distribution of the dormant PV sites, except for the RIPV, significantly differed from that of the acute PVEI sites (P < 0.05). Further, AF recurred significantly in the Group 2 patients as compared to those in Group 1 during 16 ± 6.1 months of follow-up (P < 0.05). Conclusion: PV carina region origins may partly be responsible for an acute PVEI and potential recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 494-500, May 2010) [source]

Focal Atrial Tachycardia Originating from the Left Atrial Appendage: Electrocardiographic and Electrophysiologic Characterization and Long-Term Outcomes of Radiofrequency Ablation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2007
WANG YUN-LONG M.D.
Introduction: This study sought to investigate electrophysiologic characteristics and radiofrequency ablation (RFA) in patients with focal atrial tachycardia (AT) arising from the left atrial appendage (LAA). Methods: This study included seven patients undergoing RFA with focal AT. Activation mapping was performed during tachycardia to identify an earlier activation in the left atria and the LAA. The atrial appendage angiography was performed to identify the origin in the LAA before and after RFA. Results: AT occurred spontaneously or was induced by isoproterenol infusion rather than programmed extrastimulation and burst atrial pacing in any patient. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P wave was highly positive in inferior leads in all patients. Lead V1 showed upright or biphasic (±) component in all patients. Lead V2,V6 showed an isoelectric component in five patients or an upright component with low amplitude (<0.1 mV) in two patients. Earliest endocardial activity occurred at the distal coronary sinus (CS) ahead of P wave in all seven patients. Mean tachycardia cycle length was 381 ± 34 msec and the earliest endocardial activation at the successful RFA site occurred 42.3 ± 9.6 msec before the onset of P wave. RFA was acutely successful in all seven patients. Long-term success was achieved in seven of the seven over a mean follow-up of 24 ± 5 months. Conclusions: The LAA is an uncommon site of origin for focal AT (3%). There were consistent P-wave morphology and endocardial activation associated with this type of AT. The LAA focal ablation is safe and effective. Long-term success was achieved with focal ablation in all patients. [source]

Clinical Implications of Reconnection Between the Left Atrium and Isolated Pulmonary Veins Provoked by Adenosine Triphosphate after Extensive Encircling Pulmonary Vein Isolation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2007
HITOSHI HACHIYA M.D.
Introduction: Dormant pulmonary vein (PV) conduction can be provoked by adenosine triphosphate (ATP) after extensive encircling pulmonary vein isolation (EEPVI). However, the clinical implication of reconnection between the left atrium (LA) and isolated PVs provoked by ATP (ATP-reconnection) remains unknown. Methods and Results: We studied the clinical consequences of ATP-reconnection during intravenous isoproterenol infusion (ISP-infusion). EEPVI severs conduction between the LA and ipsilateral PVs at their junction. Radiofrequency energy is applied at a distance from the PV ostia guided by double Lasso catheters placed within the ipsilateral superior and inferior PVs. This study comprised 82 patients (67 men, 56 ± 9 years old) with atrial fibrillation (AF) who underwent injection of ATP during ISP infusion after successful EEPVI (ATP(+) group). We compared clinical characteristics of 170 patients who underwent earlier EEPVI prior to our use of ATP injection after successful EEPVI (ATP(N/D) group) with those of ATP(+) group patients who underwent one session of EEPVI. ATP-reconnection occurred in 34 (41%) of 82 ATP(+) group patients. Additional radiofrequency applications were performed to eliminate ATP-reconnection in all ipsilateral PVs. Continuous ATP-reconnection of more than 20 seconds duration occurred in six (7.3%) of 82 patients. A total of 102 (60%) of 170 patients in the ATP(N/D) group had no recurrence of AF, whereas 60 (73%) of 82 ATP(+) group patients who underwent only one EEPVI session have had no recurrence of AF in a 6.1 ± 3.3-month follow-up period (P = 0.04). Conclusion: Radiofrequency application for provoked ATP-reconnection may reduce clinical AF recurrence. [source]

Effects of Isoproterenol and Amiodarone on the Double Potential Interval After Ablation of the Cavotricuspid Isthmus

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2003
HIROSHI TADA M.D.
Introduction: A corridor of double potentials along the ablation line has been recognized to be an indicator of complete cavotricuspid isthmus block. Isoproterenol is used to confirm cavotricuspid isthmus block, but the effects of isoproterenol on the double potential interval (DPI), either in the absence or presence of amiodarone, are unknown. Methods and Results: Thirty-two patients with isthmus-dependent atrial flutter underwent successful ablation of the cavotricuspid isthmus. The procedure was performed in the drug-free state in 23 patients, and 2 to 7 days after discontinuation of chronic amiodarone therapy in 9 patients. Electrograms recorded along the ablation line before and during isoproterenol infusion were analyzed after isthmus block was achieved. Double potentials were recorded along the entire ablation line upon achievement of complete isthmus block in all patients. The DPI in 9 patients treated with amiodarone was longer than in the other patients (147 ± 32 msec vs 119 ± 19 msec, P < 0.001). The DPI increased as the pacing cycle length shortened in patients treated with amiodarone, but not in the other patients. At all pacing cycle lengths, isoproterenol shortened the DPI to a greater extent in the patients treated with amiodarone than in the other patients. Conclusion: Amiodarone results in rate-dependent prolongation of the DPI during coronary sinus pacing after ablation of the cavotricuspid isthmus. Isoproterenol shortens the DPI despite the presence of complete isthmus block, and this effect is accentuated in the presence of amiodarone. (J Cardiovasc Electrophysiol, Vol. 14, pp. 935-939, September 2003) [source]

Atrioventricular Nodal Reentrant Tachycardia in Children: Effect of Slow Pathway Ablation on Fast Pathway Function

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2002
GEORGE F. VAN HARE M.D.
AV Nodal Reentry in Children.Introduction: Prior studies in adults have shown significant shortening of the fast pathway effective refractory period after successful slow pathway ablation. As differences between adults and children exist in other characteristics of AV nodal reentrant tachycardia (AVNRT), we sought to characterize the effect of slow pathway ablation or modification in a multicenter study of pediatric patients. Methods and Results: Data from procedures in pediatric patients were gathered retrospectively from five institutions. Entry criteria were age < 21 years, typical AVNRT inducible with/without isoproterenol infusion, and attempted slow pathway ablation or modification. Dual AV nodal pathways were defined as those with > 50 msec jump in A2-H2 with a 10-msec decrease in A1-A2. Successful ablation was defined as elimination of AVNRT inducibility. A total of 159 patients (age 4.4 to 21 years, mean 13.1) were studied and had attempted slow pathway ablation. AVNRT was inducible in the baseline state in 74 (47%) of 159 patients and with isoproterenol in the remainder. Dual AV nodal pathways were noted in 98 (62%) of 159 patients in the baseline state. Ablation was successful in 154 (97%) of 159 patients. In patients with dual AV nodal pathways and successful slow pathway ablation, the mean fast pathway effective refractory period was 343 ± 68 msec before ablation and 263 ± 64 msec after ablation. Mean decrease in the fast pathway effective refractory period was 81 ± 82 msec (P < 0.0001) and was not explained by changes in autonomic tone, as measured by changes in sinus cycle length during the ablation procedure. Electrophysiologic measurements were correlated with age. Fast pathway effective refractory period was related to age both before (P = 0.0044) and after ablation (P < 0.0001). AV block cycle length was related to age both before (P = 0.0005) and after ablation (P < 0.0001). However, in dual AV nodal pathway patients, the magnitude of change in the fast pathway effective refractory period after ablation was not related to age. Conclusion: Lack of clear dual AV node physiology is common in pediatric patients with inducible AVNRT (38%). Fast pathway effective refractory period shortens substantially in response to slow pathway ablation. The magnitude of change is large compared with adult reports and is not completely explained by changes in autonomic tone. Prospective studies in children using autonomic blockade are needed. [source]

Usefulness of the Adenosine Triphosphate with a Sufficient Observation Period for Detecting Reconduction after Pulmonary Vein Isolation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2009
YUICHI NINOMIYA M.D.
Background: Although reconduction after pulmonary vein (PV) isolation is considered to play a key role in the recurrence of paroxysmal atrial fibrillation (AF), there have been few reports regarding the precise time course of early reconduction. Several studies have suggested that transient PV reconduction facilitated by adenosine may predict long-term AF recurrence. This study was designed to clarify the incidence and time course of early reconduction after PVI during the procedure and to confirm whether the use of ATP after a certain observation period was useful to detect early reconduction after PVI. Methods: In 21 patients (18 males, 56 ± 11 years) with drug refractory AF, radiofrequency circumferential PV antrum ablation was performed in all 4 PVs. After the completion of isolation, electrograms in each PV were repeatedly recorded (1.98 ± 0.57 times per PV) using a circular mapping catheter for an observation period of 87 ± 29 minutes. After isolation of all 4 PVs, 30 mg of adenosine triphosphate (ATP) was administered during isoproterenol infusion. Results: PV electrical isolation was initially achieved in all 81 PVs. During the observation period, 12 (15%) PVs in 10 (48%) of 21 patients exhibited spontaneous reconduction. Among the remaining 69 PVs, 8 (12%) additional PVs had reconduction with the use of ATP. All PV reconduction was successfully eliminated by 4.5 ± 2.2 additional radiofrequency applications. Conclusion: A sufficient observation period and the use of ATP are useful to detect early reconduction after PV isolation. [source]

High Density Endocardial Mapping of Shifts in the Site of Earliest Depolarization During Sinus Rhythm and Sinus Tachycardia

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4p1 2003
TIM R. BETTS
BETTS, T.R., et al.: High Density Endocardial Mapping of Shifts in the Site of Earliest Depolarization During Sinus Rhythm and Sinus Tachycardia.Previous mapping studies of sinus rhythm suggest faster rates arise from more cranial sites within the lateral right atrium. In the intact, beating heart, mapping has been limited to epicardial plaques or single endocardial catheters. The present study was designed to examine shifts in the site of the earliest endocardial depolarization during sinus rhythm and sinus tachycardia using high density activation mapping. Noncontact mapping of the right atrium during sinus rhythm was performed on ten anesthetized swine. Recordings were made during sinus rhythm, phenylephrine infusion, and isoproterenol infusion. The hearts were then excised and the histological sinus node identified. The mean minimum and maximum cycle lengths recorded were355 ± 43and717 ± 108 ms. A median of three (range two to five) sites of earliest endocardial depolarization were documented in each animal. With increasing heart rate the site of earliest endocardial depolarization remained stationary until a sudden shift in a cranial or caudal direction, often to sites beyond the histological sinoatrial node. The endocardial shift was unpredictable with considerable variation between animals; however, faster rates arose from more cranial sites(r = 0.46, P = 0.023). There was no difference in the mean cycle length of sinus rhythm originating from specific positions on the terminal crest(r = 0.44, P = 0.17). Cranial sites displayed a more diffuse pattern of early depolarization than caudal sites. In the porcine heart the relationship between heart rate and site of earliest endocardial depolarization shows considerable variation between individual animals. These findings may have implications for clinical mapping and ablation procedures. (PACE 2003; 26[Pt. I]:874,882) [source]