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AV Block (av + block)

Distribution by Scientific Domains
Medical Sciences92%
2 Other Domains8%

Kinds of AV Block

  • complete av block
    		•
  • degree av block
    		•

    Selected Abstracts

    Biventricular Versus Right Ventricular Pacing in Patients with AV Block (BLOCK HF): Clinical Study Design and Rationale

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2007
    ANNE B. CURTIS M.D.
    Background: Right ventricular (RV) pacing restores ventricular systole in patients with atrioventricular (AV) block, yet recent studies have suggested that in patients with AV block and left ventricular (LV) dysfunction, RV pacing may exacerbate the progression to heart failure (HF). BLOCK HF is a prospective, multi-center, randomized, double-blind, controlled trial designed to determine whether patients with AV block, LV dysfunction (EF , 50%), and mild to moderate HF (NYHA I-III) who require pacing benefit from biventricular (BiV) pacing, compared with RV pacing alone. Objective: The primary objective of this trial is to determine whether the time to first event (all-cause mortality, heart failure-related urgent care, or a , 15% increase in left ventricular end systolic volume index [LVESVI]) for patients with BiV pacing is superior to that of patients with RV pacing. Methods: Patients with AV block and LV dysfunction who require permanent pacing and undergo successful implantation of a commercial Medtronic CRT device, with or without an ICD, will be randomized to BiV or RV pacing. Patients are followed at least every 6 months until study closure. Up to 1,636 patients may be enrolled in 150 centers worldwide. Conclusion: BLOCK HF is a large, randomized, clinical study in pacing-indicated patients with AV block, mild to moderate HF symptoms, and LV dysfunction to determine whether BiV pacing is superior to RV pacing in slowing the progression of HF. [source]

    Second-degree atrioventricular block (Mobitz Type I) in an adolescent with anorexia nervosa: Intrinsic or acquired conduction abnormality

    INTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 6 2009
    Nuray Ö. Kanbur MD
    Abstract Anorexia nervosa (AN) can cause both functional and structural cardiac complications, including a variety of different conduction abnormalities. This is the first case report of symptomatic diurnal second-degree atrioventricular (AV) block (Mobitz Type I) in an adolescent with AN. We present a 12-year-old girl with AN, restrictor sub-type who reported cardiac symptoms during weight gain, at the time of the initial diagnosis of AV block. Second-degree AV block (Mobitz Type I) is discussed as a possible complication of the AN, as well as being an intrinsic conduction system disease. © 2009 by Wiley Periodicals, Inc. Int J Eat Disord 2009 [source]

    Safety of Deferring the Reimplantation of Pacing Systems After Their Removal for Infectious Complications in Selected Patients: A 1-Year Follow-Up Study

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2010
    ELOI MARIJON M.D.
    Introduction: Recent expert consensus guidelines mention that one of the principles for infected device replacement following removal is to "reevaluate carefully if there is a continued need for a new cardiac device replacement." This is a Class I recommendation, which nevertheless suffers from a very low level of evidence (level of evidence C), since no study has revisited the systematic practice of reimplanting the same device based on a meticulous clinical reassessment. In the present paper, we examined the safety of withholding the implantation of pacing systems in selected patients. Methods and Results: Between January 2005 and December 2007, 188 consecutive patients underwent extractions of infected pacing systems at 2 medical centers. "Low-risk" patients were identified by (1) a spontaneous heart rate >45 bpm, (2) no symptomatic asystole during monitoring, (3) QRS duration <120 ms when history of AV block was noted, (4) no high-degree AV block during continuous monitoring. They remained device-free, unless an adverse clinical event occurred mandating the reimplantation. The primary study endpoint was rate of sudden death and syncope after a 12-month follow-up. Among the 74 (39.4%) "low-risk" patients, a single patient suffered a bradycardia-related syncopal event corresponding to a 1.3% (95% CI, 0.0,3.9) rate of primary endpoint. Pacing systems were also reimplanted in 24 patients (32.4%) for syncope (n = 1), nonsevere bradycardia-reated symptoms (n = 17), cardiac resynchronization (n = 2), and for reassurance in 4 asymptomatic patients. Conclusion: After removal of infected pacing systems, these preliminary data demonstrated that a strategy of nonsystematic device reimplantation associated with close surveillance was safe in "low-risk" patients, allowing the administration of antimicrobials in a device-free state. (J Cardiovasc Electrophysiol, Vol. 21, pp. 540-544, May 2010) [source]

    Electrocardiographic Findings, Device Therapies, and Comorbidities in Octogenarian Implantable Defibrillator Recipients

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2010
    JAMES D. DANIELS M.D.
    Implantable Defibrillators in Octogenarians.,Background: The use of implantable cardioverter-defibrillators (ICDs) in octogenarians is poorly defined. Objective: To assess baseline electrocardiographic (ECG) findings, arrhythmia episodes, and development of severe nonarrhythmic illness or death in patients aged ,80 years at ICD implantation, and to compare them with younger patients. Methods: Medical records and device interrogations for 199 patients ,70 years old who underwent ICD implantation were reviewed. Patients were divided into 3 groups based on age at the time of implant: age 70,74 (group 1; 88 patients), age 75,79 (group 2; 67 patients), and age ,80 (group 3; 44 patients). Results: ECGs: Octogenarians were more likely to have sinus bradycardia (SB) (P = 0.047) and left bundle branch block (LBBB) (P = 0.043) compared to younger patients. There was no difference among groups in the proportion of patients with atrial fibrillation or any degree of AV block. Therapies: There was no difference between age groups in any therapy (P = 0.78), appropriate therapy (P = 0.54), or inappropriate therapy (P = 0.21) per patient-year. There was no difference between groups in time-to-first therapy of any type (P = 0.71). Nonarrhythmic death/morbidity: There was no difference between groups in time to death or serious illness. Conclusion: Our study is the first to evaluate in detail the therapies received by octogenarians after ICD placement. The higher incidence of SB and LBBB might influence the number of pacing sites in octogenarian patients. Very elderly patients have similar rates of arrhythmic episodes and development of severe comorbidities as septuagenarians, and they should not be denied ICD implantation based solely on age. (J Cardiovasc Electrophysiol, Vol. 21, pp. 236,241, March 2010) [source]

    Severe Atrioventricular Decoupling, Uncoupling, and Ventriculoatrial Coupling During Enhanced Atrial Pacing: Incidence, Mechanisms, and Implications for Minimizing Right Ventricular Pacing in ICD Patients

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2008
    MICHAEL O. SWEENEY M.D.
    Background: Enhanced AAI/R pacing minimizes right ventricular pacing but may permit or induce AV decoupling (AV-DC) due to unrestricted AV intervals (AVIs). The purpose of this study was to characterize and quantify AVI behavior in a randomized trial of enhanced AAI/R pacing in ICD patients. Methods: One hundred twenty-one patients in the Marquis ICD MVPÔ Study, a randomized 1-month crossover comparison of cumulative% ventricular pacing (Cum%VP) in enhanced AAIR (MVP) vs DDD/R, were analyzed. AV-DC was defined as ,40% AVIs >300 ms; VA coupling (VA-C) was defined as%V-atrial pace (AP) intervals <300 ms. Dynamic AVI behavior and increases in Cum%VP due to AV block (AV uncoupling, AV-UC) were characterized using Holters with real-time ICD telemetry. Results: AV-DC occurred in 17 (14%) of patients. Baseline PR, amiodarone, nighttime, lower rate >60 beats/min, rate response, and Cum%AP were associated with longer AVIs. Logistic regression identified baseline PR (odds ratio [OR]= 1.024, 95% confidence interval [CI] 1.007,1.042; P = 0.005), and Cum%AP (OR = 1.089, 95% CI 1.027,1.154; P = 0.004) as predictors of AV-DC. AV-DC was associated with ,10-fold increases in both Cum%VP (13.6 ± 28.3% vs 1.2 ± 3.9%; P = 0.023) due to transient AV-UC) and VA-C (6.0 ± 17.5% vs 0.5 ± 1.2%, P = 0.028). AV coupling (<40% AVIs >300 ms) was preserved in 104 (86%) patients. Conclusions: AV-DC, VA-C, and AV-UC may be worsened or induced by enhanced AAI/R pacing. Conservative programming of lower rate and rate response should reduce the risk of AV-DC by reducing Cum%AP. [source]

    Biventricular Versus Right Ventricular Pacing in Patients with AV Block (BLOCK HF): Clinical Study Design and Rationale

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2007
    ANNE B. CURTIS M.D.
    Background: Right ventricular (RV) pacing restores ventricular systole in patients with atrioventricular (AV) block, yet recent studies have suggested that in patients with AV block and left ventricular (LV) dysfunction, RV pacing may exacerbate the progression to heart failure (HF). BLOCK HF is a prospective, multi-center, randomized, double-blind, controlled trial designed to determine whether patients with AV block, LV dysfunction (EF , 50%), and mild to moderate HF (NYHA I-III) who require pacing benefit from biventricular (BiV) pacing, compared with RV pacing alone. Objective: The primary objective of this trial is to determine whether the time to first event (all-cause mortality, heart failure-related urgent care, or a , 15% increase in left ventricular end systolic volume index [LVESVI]) for patients with BiV pacing is superior to that of patients with RV pacing. Methods: Patients with AV block and LV dysfunction who require permanent pacing and undergo successful implantation of a commercial Medtronic CRT device, with or without an ICD, will be randomized to BiV or RV pacing. Patients are followed at least every 6 months until study closure. Up to 1,636 patients may be enrolled in 150 centers worldwide. Conclusion: BLOCK HF is a large, randomized, clinical study in pacing-indicated patients with AV block, mild to moderate HF symptoms, and LV dysfunction to determine whether BiV pacing is superior to RV pacing in slowing the progression of HF. [source]

    Multicenter, Prospective, Randomized Safety and Efficacy Study of a New Atrial-Based Managed Ventricular Pacing Mode (MVP) in Dual Chamber ICDs

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2005
    MICHAEL O. SWEENEY M.D.
    Background: Ventricular desynchronization caused by right ventricular pacing may impair ventricular function and increase risk of heart failure (CHF), atrial fibrillation (AF), and death. Conventional DDD/R mode often results in high cumulative percentage ventricular pacing (Cum%VP). We hypothesized that a new managed ventricular pacing mode (MVP) would safely provide AAI/R pacing with ventricular monitoring and DDD/R during AV block (AVB) and reduce Cum%VP compared to DDD/R. Methods: MVP RAMware was downloaded in 181 patients with Marquis DR ICDs. Patients were initially randomized to either MVP or DDD/R for 1 month, then crossed over to the opposite mode for 1 month. ICD diagnostics were analyzed for cumulative percentage atrial pacing (Cum%AP), Cum%VP, and duration of DDD/R pacing for spontaneous AVB. Results: Baseline characteristics included age 66 ± 12 years, EF 36 ± 14%, and NYHA Class II,III 36%. Baseline PR interval was 190 ± 53 msec and programmed AV intervals (DDD/R) were 216 ± 50 (paced)/189 ± 53 (sensed) msec. Mean Cum%VP was significantly lower in MVP versus DDD/R (4.1 ± 16.3 vs 73.8 ± 32.5, P < 0.0001). The median absolute and relative reductions in Cum%VP during MVP were 85.0 and 99.9, respectively. Mean Cum%AP was not different between MVP versus DDD/R (48.7 ± 38.5 vs 47.3 ± 38.4, P = 0.83). During MVP overall time spent in AAI/R was 89.6% (intrinsic conduction), DDD/R 6.7% (intermittent AVB), and DDI/R 3.7% (AF). No adverse events were attributed to MVP. Conclusions: MVP safely achieves functional atrial pacing by limiting ventricular pacing to periods of intermittent AVB and AF in ICD patients, significantly reducing Cum%VP compared to DDD/R. MVP is a universal pacing mode that adapts to AVB and AF, providing both atrial pacing and ventricular pacing support when needed. [source]

    Identification and Ablation of Three Types of Ventricular Tachycardia Involving the His-Purkinje System in Patients with Heart Disease

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2004
    GUSTAVO LOPERA M.D.
    Introduction: Ventricular tachycardia (VT) with involvement of the His-Purkinje system (HPS) can be difficult to recognize in patients with heart disease, but it may be particularly susceptible to ablation targeting the HPS. This study defines the incidence and types of HPS involvement in VT. Methods and Results: Involvement of the HPS was sought during electrophysiologic study with catheter mapping in 234 consecutive patients referred for catheter ablation of recurrent VT associated with heart disease. HPS VT was observed in 20 (8.5%) patients (mean ejection fraction 29%± 17%); in 9 (11%) of 81 patients with nonischemic heart disease and 11 (7.1%) of 153 patients with coronary artery disease (P = NS). Three types of HPS VT were observed: 16 patients (group 1) had typical bundle branch reentry, 2 patients (group 2) had bundle branch reentry and interfascicular reentry, and 2 patients (group 3) had VT consistent with a focal origin in the distal HPS. In all three groups, the VT QRS had morphologic similarity to the sinus rhythm QRS. Ablation of HPS VT was successful in all patients in whom it was attempted but produced high-degree AV block in 6 (30%). In 12 patients (60%), other VTs due to reentry through scar also were inducible. Conclusion: Involvement of the HPS in VT associated with heart disease has three distinct clinical forms, all of which are susceptible to ablation. Ablation often is not sufficient as the sole therapy due to other induced VT's and conduction abnormalities, requiring pacemaker and/or defibrillator implantation. (J Cardiovasc Electrophysiol, Vol. 15, pp. 52-58, January 2004) [source]

    Spontaneous Transition of 2:1 Atrioventricular Block to 1:1 Atrioventricular Conduction During Atrioventricular Nodal Reentrant Tachycardia:

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2003
    Evidence Supporting the Intra-Hisian or Infra-Hisian Area as the Site of Block
    Introduction: The incidence of spontaneous transition of 2:1 AV block to 1:1 AV conduction during AV nodal reentrant tachycardia has not been well reported. Among previous studies, controversy also existed about the site of the 2:1 AV block during AV nodal reentrant tachycardia. Methods and Results: In patients with 2:1 AV block during AV nodal reentrant tachycardia, the incidence of spontaneous transition of 2:1 AV block to 1:1 AV conduction and change of electrophysiologic properties during spontaneous transition were analyzed. Among the 20 patients with 2:1 AV block during AV nodal reentrant tachycardia, a His-bundle potential was absent in blocked beats during 2:1 AV block in 8 patients, and the maximal amplitude of the His-bundle potential in the blocked beats was the same as that in the conducted beats in 4 patients and was significantly smaller than that in the conducted beats in 8 patients (0.49 ± 0.25 mV vs 0.16 ± 0.07 mV, P = 0.007). Spontaneous transition of 2:1 AV block to 1:1 AV conduction occurred in 15 (75%) of 20 patients with 2:1 AV block during AV nodal reentrant tachycardia. Spontaneous transition of 2:1 AV block to 1:1 AV conduction was associated with transient right and/or left bundle branch block. The 1:1 AV conduction with transient bundle branch block was associated with significant His-ventricular (HV) interval prolongation (66 ± 19 ms) compared with 2:1 AV block (44 ± 6 ms, P < 0.01) and 1:1 AV conduction without bundle branch block (43 ± 6 ms, P < 0.01). Conclusion: The 2:1 AV block during AV nodal reentrant tachycardia is functional; the level of block is demonstrated to be within or below the His bundle in a majority of patients with 2:1 AV block during AV nodal reentrant tachycardia, and a minority are possibly high in the junction between the AV node and His bundle. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1337-1341, December 2003) [source]

    Evaluation of Myocardial Performance with Conventional Single-Site Ventricular Pacing and Biventricular Pacing in a Canine Model of Atrioventricular Block

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2003
    PATRICIO A. FRIAS M.D.
    Introduction: The aim of this study was to evaluate epicardial biventricular pacing as a means of maintaining synchronous ventricular activation in an acute canine model of AV block with normal ventricular anatomy and function. Chronic single-site ventricular pacing results in dyssynchronous ventricular activation and may contribute to ventricular dysfunction. Biventricular pacing has been used successfully in adult patients with congestive heart failure. Methods and Results: This was an acute study of open chest mongrel dogs (n = 13). ECG, left ventricular (LV), aortic, and pulmonary arterial pressures were measured. LV impedance catheters were used to assess cardiodynamics using instantaneous LV pressure-volume relations (PVR). Following radiofrequency ablation of the AV node, a temporary pacemaker was programmed 10 beats/min above the intrinsic atrial rate, with an AV interval similar to the baseline intrinsic PR interval. The pacing protocol consisted of 5-minute intervals with the following lead configurations: right atrium-right ventricular apex (RA-RVA), RA-LV apex (LVA), and RA-biventricular using combinations of four ventricular sites (RVA, RV outflow tract [RVOT], LVA, LV base [LVB]). RA-RVA was used as the experimental control. LV systolic mechanics, as measured by the slope of the end-systolic (Ees) PVR (ESPVR, mmHg/cc), was statistically greater (P < 0.05) with all modes of biventricular pacing (RA-RVA/LVA 20.0 ± 2.9, RA-RVA/LVB 18.4 ± 2.9, RA-RVOT/LVA 15.1 ± 1.8, RA-RVOT/LVB 17.6 ± 2.9) compared to single-site ventricular pacing (RA-RVA 12.8 ± 1.6). Concurrent with this improvement in myocardial performance was a shortening of the QRS duration (RA-RVA 97.7 ± 2.9 vs RA-RVA/LVA 75.7 ± 4.9, RA-RVA/LVB 70.3 ± 4.9, RA-RVOT/LVA 65.3 ± 4.4, and RA-RVOT/LVB 76.7 ± 5.9, P < 0.05). Conclusion: In this acute canine model of AV block, QRS duration shortened and LV performance improved with epicardial biventricular pacing compared to standard single-site ventricular pacing. (J Cardiovasc Electrophysiol, Vol. 14, pp. 996-1000, September 2003) [source]

    Changes in Left Ventricular Repolarization and Ion Channel Currents Following a Transient Rate Increase Superimposed on Bradycardia in Anesthetized Dogs

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2000
    MICHAEL RUBART M.D.
    Electrical Remodeling of the Heart due to Rate. Introduction: We previously demonstrated in dogs that a transient rate increase superimposed on bradycardia causes prolongation of ventricular refractoriness that persists for hours after resumption of bradycardia. In this study, we examined changes in membrane currents that are associated with this phenomenon. Methods and Results: The whole cell, patch clamp technique was used to record transmembrane voltages and currents, respectively, in single mid-myocardial left ventricular myocytes from dogs with 1 week of complete AV block; dogs either underwent 1 hour of left ventricular pacing at 120 beats/min or did not undergo pacing. Pacing significantly heightened mean phase 1 and peak plateau amplitudes by ,6 and ,3 mV, respectively (P < 0.02). and prolonged action potential duration at 90% repolarization from 235 ± 8 msec to 278 ± 8 msec (1 Hz; P = 0.02). Rapid pacing-induced changes in transmembrane ionic currents included (1) a more pronounced cumulative inactivation of the 4-aminopyridine-sensitive transient outward K+ current, I to over the range of physiologic frequencies, resulting from a ,30% decrease in the population of quickly reactivating channels; (2) increases in peak density of L-type Ca2+ currents, Ica.I.' by 15% to 35% between +10 and +60 mV; and (3) increases in peak density of the Ca2+ -activated chloride current, ICl.Ca' by 30% to 120% between +30 and +50 mV. Conclusion: Frequency-dependent reduction in Ito combined with enhanced ICa.I. causes an increase in net inward current that may he responsible for the observed changes in ventricular repolarization. This augmentation of net cation influx is partially antagonized by an increase in outward ICa.Cl. [source]

    Bimodal RR Interval Distribution in Chronic Atrial Fibrillation:

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2000
    Impact of Dual Atrioventricular Nodal Physiology on Long-Term Rate Control after Catheter Ablation of the Posterior Atrionodal Input
    Bimodal RR Interval Distribution, Introduction: Radiofrequency (RF) catheter modification of the AV node hi patients with atrial fibrillation (AF) is limited by an unpredictable decrease of the ventricular rate and a wish incidence of permanent AV block, A bimodal RR histogram has been suggested to serve as a predictor for successful outcome but the corresponding AV node properties have never been characterized, We hypothesized that a bimodal histogram indicates dual AV nodal physiology and predicts a better outcome after AV node modification in chronic AF. Methods and Results: Thirty-seven patients were prospectively subdivided into two groups according to the RR histogram of 24-hour ECC monitoring, Before to RF ablation, internal cardioversion and programmed stimulation were performed, Among the 22 patients (group I) with a bimodal RR histogram, dual AV nodal physiology was found in 17 (779f) patients, Ablation significantly decreased ventricular rate with loss of the peak of short RR cycles after ablation (mean and maximal ventricular rates: 32% and 35% rate reduction, respectively; P < 0,01), In 15 patients with a unimodal RR histogram (group II), dual AV nodal physiology was found in 2 (13%), and rate reductions were 16% and 17%, respectively, At 6 months, 3 (14%) patients in group 1 and 6 (40%) in group II underwent elective AV nodal ablation with pacemaker implantation due to intolerable rapid ventricular response to AF. Conclusion: Bimodal RR interval distribution during chronic AF suggests the presence of dual AV nodal physiology and predicts a better outcome of RF ablation of the posterior atrionocdal input. [source]

    Nonfluoroscopic Three-Dimensional Mapping for Arrhythmia Ablation: Tool or Toy?

    JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2000
    APICHAI KHONGPHATTHANAYOTHIN M.D.
    Arrhythmia Ahlation with Nonfluoroscopic 3D Mapping. Introduction: Conventional mapping and ablation rely on fluoroscopy, which can result in imprecise positioning of the ablation catheter and long fluoroscopic exposure times. We evaluated a nonfluoroscopic three-dimensional mapping system, termed CARTO, and compared the results of ablation using this technique with those of conventional mapping. Methods and Results: We compared the results of 88 arrhythmia ablations (79 patients) using CARTO with 100 ablations (94 patients) using the conventional technique. The ablations were separated into four groups: (1) AV nodal reentrant tachycardia (AVNRT); (2) atrial tachycardia/flutter; (3) ventricular tacbycardia (VT); and (4) bypass tract tachycardia. We compared the success rate, complications, and fluoroscopy and procedure times. Tbe ablation outcomes were excellent and comparable in all four types of the arrhythmias between the two techniques. Major complications included one cardiac tamponade in each group and one second-degree AV block in the conventional group. Fluoroscopy time was shorter using the CARTO technique: 10 ± 7 versus 27 ± 15 minutes for AVNRT (P < 0.01), 18 ± 17 versus 44 ± 23 minutes for atrial tachycardia and flutter (P < 0.01), 15 ± 12 versus 34 ± 31 minutes for VT (P < 0.05), and 21 ± 14 versus 53 ± 32 minutes for bypass tract tachycardia (P < 0.01). Procedure times were similar except for the bypass tract patients, wbich was shorter in the CARTO group, 4 ± 1.3 versus 5.5 ± 2.5 hours (P < 0.01). Conclusion: The electroanatomic three-dimensional mapping technique reduced fluoroscopy time and resulted in excellent outcome without increasing the procedure time. [source]

    Fetal arrhythmia: Prenatal diagnosis and perinatal management

    JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 4 2009
    Yasuki Maeno
    Abstract The importance of managing fetal arrhythmia has increased over the past three decades. Although most fetal arrhythmias are benign, some types cause fetal hydrops and can lead to fetal death. With the aim of improving the outcome in such cases, various studies for prenatal diagnosis and perinatal management have been published. Detailed analysis of the type of arrhythmia in utero is possible using M-mode and Doppler echocardiography. In particular, a simultaneous record of Doppler waveform at the superior venous cava and the ascending aorta has become an important and useful method of assessing the interval between atrial and ventricular contractions. Common causes of fetal tachycardia (ventricular heart rate faster than 180 bpm), are paroxysmal supraventricular tachycardia (SVT) with 1:1 atrioventricular (AV) relation and atrial flutter with 2:1 AV relation. Of fetal SVT, short ventriculo-atrial (VA) interval tachycardia due to atrioventricular reentrant tachycardia is more common than long VA interval. Most fetuses with tachycardia are successfully treated in utero by transplacental administration of antiarrhythmic drugs. Digoxin is widely accepted as a first-line antiarrhythmic drug. Sotalol, flecainide and amiodarone are used as second-line drugs when digoxin fails to achieve conversion to sinus rhythm. Fetal bradycardia is diagnosed when the fetal ventricular heart rate is slower than 100 bpm, mainly due to AV block. Approximately half of all cases are caused by associated congenital heart disease, and the remaining cases that have normal cardiac structure are often caused by maternal SS-A antibody. The efficacy of prenatal treatment for fetal AV block is limited compared with treatment for fetal tachycardia. Beta stimulants and steroids have been reported as effective transplacental treatments for fetal AV block. Perinatal management based on prospective clinical study protocol rather than individual experience is crucial for further improvement of outcome in fetuses with tachycardia and bradycardia. [source]

    CLOSTRIDIUM TETANUS INFECTION IN 13 DOGS AND ONE CAT

    JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue S1 2004
    C Bandt
    Clostridium tetani infection is uncommon in dogs and cats. Up to this point in time just single case reports have been published in veterinary medicine. The goal of this retrospective study was to describe the clinical features and outcome of 13 dogs and one cat affected with Clostridium tetani. The medical records of the last ten year were reviewed. Dogs and cats that were identified as being infected with Clostridium tetani on the basis of characteristic clinical signs and/or bacterial culture from infected wounds were eligible for study inclusion. Thirteen dogs and one cat met the criteria for study inclusion. Six different breeds and mix-breed dogs were affected, German Shepherd dogs (n=4, 29%) and Labrador retriever (n=3, 21%) were the most frequently affected breeds. Observed clinical complications were ventricular aspiration pneumonia (n=7), laryngeal spasm (n=6), hypersalivation (n=4), ventricular tachycardia (n=3), and third degree AV block (n=1). Median days from onset of clinical signs until first signs of improvement were 10 days (range: 9,12 days). Median hospitalisation time was 18 days (range: 14,22 days). Six animals showed full recovery and 8 animals died or were euthanized. Death was associated with acute onset of ventricular tachycardia in 2 dogs, 1 dog died with non-responsive third degree AV-block, 3 dogs died after developing aspiration pneumonia, and 1 dog died of unknown causes. [source]

    Stepwise Transition of 2:1 Atrio-Ventricular Block to 1:1 Conduction Induced by Ventricular Premature Beats in a Patient with Atypical AVNRT

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2010
    ANTONIO SORGENTE M.D.
    A 55-year-old man with a 2-year history of recurrent paroxysmal palpitations and with an electrocardiogram documentation of atypical atrioventricular nodal re-entrant tachycardia (AVNRT) was referred to us for catheter ablation. After an initial ablation attempt, several episodes of atypical AVNRT were induced. During one of these episodes, we documented a stepwise transition of 2:1 atrioventricular block to 1:1 conduction, following two single ventricular premature beats. This phenomenon confirmed the functional nature of the AV block during AVNRT and indirectly its infra-nodal location. (PACE 2010; 33:e20,e23) [source]

    Utility of Noninvasive, Mobile, Continuous Outpatient Rhythm Monitoring to Diagnose Seizure-Related Arrhythmias

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 7 2009
    KEVIN DRIVER M.D.
    The identification of patients with a diagnosis of seizure disorder who are also at risk for clinically significant bradycardia and/or tachycardia may require long-term cardiac rhythm monitoring. Noninvasive, continuous, outpatient cardiac rhythm monitoring may be useful for such clinical scenarios. The study group consisted of two male patients with a history of seizure disorder involving loss of consciousness. Clinical data and results of electrocardiography, echocardiography, electroencephelography, and continuous, mobile, outpatient cardiac rhythm monitoring are described. In the first patient, while cardiac bradyarrhythmias were secondary to seizures, sinus arrest most likely complicated the episodes by leading to more prolonged states of unconsciousness. In the second patient, permanent pacemaker implantation for AV block averted all clinical events previously attributed to seizures. Despite the different causal relationships between seizures and bradyarrhythmias in these two patients, mobile, cardiac outpatient telemetry was successful in diagnosing the contribution of cardiac dysrhythmia, leading to permanent pacemaker implantation. A diagnostic strategy that incorporates mobile, noninvasive, continuous, outpatient cardiac rhythm monitoring can effectively be utilized to diagnose significant seizure-related arrhythmias. [source]

    Relationship between Amplitude and Timing of Heart Sounds and Endocardial Acceleration

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009
    AUDE TASSIN M.D.
    Objective: To study the correlation between heart sounds and peak endocardial acceleration (PEA) amplitudes and timings, by modulation of paced atrioventricular (AV) delay in recipients of dual chamber pacemakers. Methods: Ten recipients of dual chamber pacemakers implanted for high-degree AV block were studied. Endocardial acceleration (EA) and phonocardiographic and electrocardiographic signals were recorded during performance of an AV delay scan in VDD and DDD modes. Results: First PEA (PEA I) and first heart sound (S1) changed similarly with the AV delay. A close intrapatient correlation was observed between S1 and PEA I amplitudes in all patients (P < 0.0001). The interpatient normalized PEA I to S1 amplitudes correlation was r = 0.89 (P < 0.0001) in DDD mode, and r = 0.81 (P < 0.0001) in VDD mode. The mean cycle-by-cycle PEA I to S1 delay was ,4.3 ± 22 ms and second PEA (PEA II) to second heart sound (S2) delay was ,7.7 ± 15 ms. Conclusions: A close correlation was observed between PEA I and S1 amplitudes and timings, and between PEA II and S2 timings. These observations support the hypothesis that PEA and heart sounds are manifestations of the same phenomena. EA might be a useful tool to monitor cardiac function. [source]

    Cryoablation for Atrioventricular Nodal Reentrant Tachycardia in Young Patients: Predictors of Recurrence

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2008
    NIKHIL K. CHANANI M.D.
    Background: Recurrence rates of atrioventricular nodal reentry tachycardia (AVNRT) after cryoablation continue to remain high despite excellent initial success rates. Our objective was to evaluate the clinical outcomes of cryoablation for AVNRT with the 4-mm and 6-mm tip cryoablation catheters in a young population and to elicit predictors of arrhythmia recurrence. Methods: We retrospectively reviewed all patients who underwent cryoablation for AVNRT at the UCSF/Stanford Pediatric Arrhythmia Center from January 2004 to February 2007. Results: One hundred fifty-four patients (age 13.7 years (3.2,24.4)) underwent cryoablation for AVNRT of which 144 patients had inducible AVNRT (123 sustained and 21 nonsustained) and 10 had presumed AVNRT. Initial success was achieved in 95% (146/154), with no difference between the 4-mm (93%) and 6-mm (98%) cryoablation catheter tips (P = 0.15). There was no permanent atrioventricular (AV) block. Transient third-degree AV block occurred in nine patients (6%), with no difference between the 4-mm (4%) and 6-mm (9%) tip (P = 0.13). AVNRT recurrence was documented in 14% in a median time of 2.5 months (0.25,20). Recurrences were lower with the 6-mm (9%) versus the 4-mm (18%) tip, but this did not reach statistical significance (P = 0.16). With univariate analysis, a longer fluoroscopy time was the only significant factor associated with recurrence. Multivariate analysis failed to identify any significant predictor of AVNRT recurrence. Conclusion: Outcomes of cryoablation for AVNRT continue to be good without the complication of AV block. We could not identify any specific parameter associated with AVNRT recurrence. Further improvements in cryoablation technique will be necessary to reduce recurrences. [source]

    How Revealing Are Insertable Loop Recorders in Pediatrics?

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2008
    PATRICIA A. FRANGINI M.D.
    Introduction: An insertable loop recorder (ILR) in patients with infrequent syncope or palpitations may be useful to decide management strategies, including clinical observation, medical therapy, pacemaker, or implantable cardioverter defibrillator (ICD). We sought to determine the diagnostic utility of the Reveal® ILR (Medtronic, Inc., Minneapolis, MN, USA) in pediatric patients. Methods: Retrospective review of clinical data, indications, findings, and therapeutic decision in 27 consecutive patients who underwent ILR implantation from 1998,2007. Results: The median age was 14.8 years (2,25 years). Indications were syncope in 24 patients and recurrent palpitations in three. Overall, eight patients had structural heart disease (six congenital heart disease, one hypertrophic cardiomyopathy, one Kawasaki), five had previous documented ventricular arrhythmias with negative evaluation including electrophysiology study, and three patients had QT prolongation. Tilt testing was performed in 10 patients, of which five had neurocardiogenic syncope but recurrent episodes despite medical therapy. After median three months (1,20 months), 17 patients presented with symptoms and the ILR memory was analyzed in 16 (no episode stored in one due to full device memory), showing asystole or transient atrioventricular (AV) block (2), sinus bradycardia (6), or normal sinus rhythm (8). Among asymptomatic patients, 3/10 had intermittent AV block or long pauses, automatically detected and stored by the ILR. In 19 of 20 patients, ILR was diagnostic (95%) and five subsequently underwent pacemaker implantation, while seven patients remained asymptomatic without ILR events. Notably, no life-threatening events were detected. The ILR was explanted in 22 patients after a median of 22 months, two due to pocket infection, 12 for battery depletion and eight after clear documentation of nonmalignant arrhythmia. Conclusions: The ILR in pediatrics is a useful adjunct to other diagnostic studies. Patient selection is critical as the ILR should not be utilized for malignant arrhythmias. A diagnosis is attained in the majority of symptomatic patients, predominantly bradyarrhythmias including pauses and intermittent AV block. [source]

    Pseudo Crosstalk Behavior in a Patient with Atrio-ventricular Block and Implanted Biventricular Defibrillator

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2007
    REGINALD T. HO M.D.
    We present a 59-year-old man with a dilated cardiomyopathy (ejection fraction = 20%), congestive heart failure and atrio-ventricular (AV) block who underwent implantation of a biventricular defibrillator (BiV ICD). While undergoing cardiac transplant evaluation for drug-refractory ventricular fibrillation, his telemetry recorded findings resembling crosstalk inhibition. Device interrogation was normal. All episodes occurred at 1:00 a.m. suggesting a routine device operation. Left ventricular capture management, a new feature that automatically measures left ventricular pacing thresholds at 1:00 a.m., had been programmed to Monitor. Understanding this sophisticated pacing algorithm might avoid confusion when operative in patients with AV block. [source]

    Inducible Atrioventricular Nodal Reentrant Echo Behind Organic 2:1 Infra-Hisian Block During Sinus Rhythm

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2006
    CHIH-SHENG CHU
    A 77-year-old male patient with an intermittent 2:1 infra-Hisian block during sinus rhythm was presented with dizziness and near-syncope. During electrophysiological (EP) study, dual atrioventricular (AV) nodal pathways and retrograde fast pathway were easily induced by atrial and ventricular programmed stimulation, respectively. A typical slow-fast AV nodal reentrant echo beat also could be demonstrated by single atrial extrastimulation. Atrioventricular nodal reentrant tachycardia (AVNRT) can occasionally exhibit 2:1 AV block. Conversely, AV nodal reentry property had been rarely reported behind 2:1 infra-Hisian block. The EP presentation from this case may support the notion that tissues below the His are not part of the reentrant circuit of AVNRT. [source]

    Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003
    JEAN-MARC DUPUIS
    DUPUIS, J.-M.,et al.: Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure.Optimization of programmed atrioventricular delay in dual chamber pacing is essential to the hemodynamic efficiency of the heart. Automatic AV delay optimization in an implanted pacemaker is highly desirable. Variations of peak endocardial acceleration (PEA) with AV delay at rest correlate well with echocardiography derived observations, particularly with end-diastolic filling and mitral valve closure timings. This suggests the possibility of devising a procedure for the automatic determination of the optimal AV delay. The aim of this study was to compare a proposed algorithm for optimal AV delay determination with an accepted echocardiographic method. Fifteen patients with high degree AV block received BEST-Living pacing systems. Automatic AV delay scans were performed at rest (60,300 ms in 20-ms steps with 60 beats per step) in DDD at 90 ppm, while simultaneously recording cycle-by-cycle PEA values, which were averaged for each AV delay to obtain a PEA versus AV delay curve. Nonlinear regression analysis based on a Boltzmann sigmoid curve was performed, and the optimal AV delay (OAVD) was chosen as the sigmoid inflection point of the regression curve. The OAVD was also evaluated for each patient using the Ritter echocardiographic method. Good sigmoid fit was obtained in 13 of 15 patients. The mean OAVD obtained by the PEA sigmoid algorithm was146.9 ± 32.1 ms, and the corresponding result obtained by echocardiography was156.4 ± 34.3 ms(range 31.8,39.7 ms). Correlation analysis yielded r = 0.79, P = 0.0012. In conclusion, OAVD estimates obtained by PEA analysis during automatic AV delay scanning are consistent with those obtained by echocardiography. The proposed algorithm can be used for automatic OAVD determination in an implanted pacemaker pulse generator. (PACE 2003; 26:[Pt. II]:210,213) [source]

    Electrocardiograms from the Turtle to the Elephant that Illustrate Interesting Physiological Phenomena

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2002
    L.A. GEDDES
    GEDDES, L.A. Electrocardiograms From the Turtle to the Elephant that Illustrate Interesting Physiological Phenomena. This article describes a collection of ECGs from many species obtained over the past 50 years. Presented are ECGs of species in which the pacemaker is a separate contractile chamber with its own action and recovery potentials. In such species, pacemaker atrial and AV block can be produced. Shortening of the atrial refractory period and the negative inotropic effect can be produced by vagal stimulation. The cardiac electrogram and stroke volume are recorded from the turtle heart. The ECG and respiration were recorded from the snake. ECG records were obtained from the anesthetized and decapitated housefly. ECG records of the rabbit show slowing when the nose encountered irritating vapors. Records from a dog with atrial fibrillation exhibit rhythmic fibrillation frequency changes correlated with respiration. In addition, in a morphinized dog with atrial fibrillation, impulses crossed the AV node only during inspiration. The ECGs of a cow and camel exhibit long P-R intervals and biphasic P waves. Finally the elephant ECG shows a clear U wave following the T wave. [source]

    Radiofrequency Catheter Ablation of an Incessant Ventricular Tachycardia Following Valve Surgery

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2002
    THORSTEN LEWALTER
    LEWALTER, T., et al.: Radiofrequency Catheter Ablation of an Incessant Ventricular Tachycardia Following Valve Surgery. Sustained monomorphic ventricular tachycardia (VT) after valve surgery represents a clinical entity with different tachycardia mechanisms. This case report describes an incessant VT after tricuspid and aortic valve replacement that did not respond to antiarrhythmic drug treatment. The tachycardia exhibited VA block and a right bundle branch block pattern with left-axis deviation, suggesting ventricular excitation via the left posterior fascicle. The electrophysiological study was limited by the prosthetic tricuspid and aortic valve replacement, therefore a transseptal approach was necessary to obtain access to the ventricular myocardium. Radiofrequency catheter ablation was performed in the proximal left bundle or distal His region with termination of the incessant VT followed by complete AV block. After pacemaker implantation using a transvenous right atrial and an epicardial ventricular lead, no VT reoccurrence could be documented. [source]

    AAIR Versus DDDR Pacing in the Bradycardia Tachycardia Syndrome: A Prospective, Randomized, Double-blind, Crossover Trial

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2001
    BERNHARD SCHWAAB
    SCHWABB, B., et al.: AAIR Versus DDDR Pacing in the Bradycardia Tachycardia Syndrome: A Prospective, Randomized, Double-blind, Crossover Trial. In 19 patients paced and medicated for bradycardia tachycardia syndrome (BTS), AAIR and DDDR pacing were compared with regard to quality of life (QoL), atrial tachyarrhythmia (AFib), exercise tolerance, and left ventricular (LV) function. Patients had a PQ interval , 240 ms during sinus rhythm, no second or third degree AV block, no bundle branch block, or bifascicular block. In DDDR mode, AV delay was optimized using the aortic time velocity integral. After 3 months, QoL was assessed by questionnaires, patients were investigated by 24-hour Holter, cardiopulmonary exercise testing (CPX) was performed, and LV function was determined by echocardiography. QoL was similar in all dimensions, except dizziness, showing a significantly lower prevalence in AAIR mode. The incidence of AFib was 12 episodes in 2 patients with AAIR versus 22 episodes in 7 patients with DDDR pacing (P = 0.072). In AAIR mode, 164 events of second and third degree AV block were detected in 7 patients (37%) with pauses between 1 and 4 seconds. During CPX, exercise duration and work load were higher in AAIR than in DDDR mode (423 ± 127 vs 402 ± 102 s and 103 ± 31 vs 96 ± 27 Watt, P < 0.05). Oxygen consumption (VO2), was similar in both modes. During echocardiography, only deceleration of early diastolic flow velocity and early diastolic closure rate of the anterior mitral valve leaflet were higher in DDD than in AAI pacing (5.16 ± 1.35 vs 3.56 ± 0.95 m/s2 and 69.2 ± 23 vs 54.1 ± 26 mm/s, P < 0.05). As preferred pacing mode, 11 patients chose DDDR, 8 patients chose AAIR. Hence, AAIR and DDDR pacing seem to be equally effective in BTS patients. In view of a considerable rate of high degree AV block during AAIR pacing, DDDR mode should be preferred for safety reasons. [source]

    Radiofrequency Energy Modification of the Atrioventricular Junction in Patients with Atrial Fibrillation: Modes of Ventricular Response Under Autonomic Blockade and Long-Term Effect

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2001
    HARALAMPOS D. KRIATSELIS
    KRIATSELIS, H.D., et al.: Radiofrequency Energy Modification of the Atrioventricular Junction in Patients with Atrial Fibrillation: Modes of Ventricular Response Under Autonomic Blockade and Long-Term Effect. The short- and long-term effect of radiofrequency (RF) modification of the AV junction on ventricular rate and left ventricular function and the different types of ventricular response during energy application under autonomic nervous blockade were assessed in 28 patients with medically refractory atrial fibrillation. During the successful RF application, ventricular rate slowed progressively (type I response, ten patients) or accelerated at first and then slowed (type II response, 11 patients). Type II response was associated with a more anterior ablation site compared to Type I response. A primary successful outcome was achieved in 21 patients. Inadvertent complete AV block developed in three patients, while in four patients AV nodal ablation was performed after an unsuccessful modification attempt. During 6-month follow-up, the ventricular rate was adequately controlled in only four patients. Among the 16 patients with a recurrence of uncontrolled AF were all 10 patients with type I response and 6 of 11 patients with type II response. One patient died suddenly 10 weeks after the procedure. [source]

    Delayed Restoration of Atrioventricular Synchrony with Beat-to-Beat Mode Switch

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2001
    FRANK BODE
    BODE, F., et al.: Delayed Restoration of Atrioventricular Synchrony with Beat-to-Beat Mode Switch. This case report describes a patient with complete AV block and a VDD pacemaker who experienced repetitive episodes of symptomatic bradycardia. Episodes occurred due to activation of an automatic beat-to-beat mode switch algorithm. After mode switch to VDI operation, the pacemaker failed to immediately switch back to AV synchronous pacing when regular sinus rhythm (, 100 beats per minute) resumed despite adequate P wave sensing. Dizziness was felt for up to several minutes of asynchronous pacing at the lower rate limit until VDD mode was restored. Episodes were completely eliminated by programming the mode switch function from an automatic beat-to-beat algorithm to a fixed rate algorithm. [source]

    Efficacy of Single Lead VDD Pacing in Patients with Impaired and Normal Left Ventricular Function

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2000
    ANDREAS SCHUCHERT
    Atrial synchronous ventricular pacing seems to be the best pacing mode for patients with advanced AV block and impaired LV function. The long-term follow-up of single lead VDD pacing was studied in 33 patients with impaired LV function and compared to 42 patients with normal LV function. All patients received the same VDD lead and VDDR pacemaker. The lead model with 13-cm AV spacing between the atrial and ventricular electrode was implanted in 89% of the patients. Follow-ups were 1, 3, 6, and 12 months after implantation. The percentage of atrial sensing and the P wave amplitude were determined at each follow-up. Minimal P wave amplitude at implantation was 2.0 ± 1.4 mV in patients with impaired and 1.7 ± 0.9 mV with normal LV function (not significant). At the 12-month follow-up, 33 patients with normal and 23 patients with depressed LV function remained paced in the VDD mode. The remaining patients died in five (impaired LV function) and seven cases (normal LV function) or their pacemakers were programmed to the VVI/VVIR pacing mode in four (impaired LV function) and three cases (normal LV function). P wave amplitude did not differ in the two groups (e.g., at month 12: impaired: 1.17 ± 0.42 mV; normal: 1.09 ± 0.49 mV). The atrial sensitivity was programmed in most patients to sensitive settings with no differences between the two groups (e.g., at month 12: impaired: 0.13 ± 0.06 mV; normal: 0.13 ± 0.05 m V). The diagnostic counters indicated nearly permanent atrial sensing (e.g., at month 12: impaired: 99.3 ± 2.2%; normal: 99.0 ± 1.0 mV). In conclusions, single lead VDD pacing restored AV synchronous ventricular pacing in patients with normal and with impaired LV function indicating that it could be an alternative to DDD pacemakers, but not to dual-chamber pacing. [source]

    Safety of Pacemaker Implantation Prior to Radiofrequency Ablation of Atrioventricular Junction in a Single Session Procedure

    PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2000
    ALESSANDRO PROCLEMER
    RF current delivery may cause acute and chronic dysfunction of previously implanted pacemakers. The aim of this study was to assess prospectively the effects of RF energy on Thera I and Kappa pacemakers in 70 consecutive patients (mean age 70 ± 11 years, mean left ventricular ejection fraction 48 ± 15%) who underwent RF ablation of the AV junction for antiarrhythmic drug refractory atrial fibrillation (permanent in 42 patients, paroxysmal in 28). These pacing systems incorporate protection elements to avoid electromagnetic interference. The pacemakers (Thera DR 7960 I in 20 patients, Thera SR 8960 1 in 30, Kappa DR 600,601 in 8, Kappa SR 700,701 in 12) were implanted prior to RF ablation in a single session procedure and were transiently programmed to VVI mode at a rate of 30 beats/min. Capsure SP and Z unibipolar leads were used. During RF application there was continuous monitoring of three ECG leads, endocavitary electrograms, and event markers. Complete AV block was achieved in all cases after 3.6 ± 2.9 RF pulses and 100 ± 75 seconds of RF energy delivery. The mean time of pacemaker implantation and RF ablation was 60 ± 20 minutes. Transient or permanent pacemaker dysfunction including under/oversensing, reversion to a "noise-mode" pacing, pacing inhibition, reprogramming, or recycling were not observed. Leads impedance, sensing, and pacing thresholds remained in the normal range in the acute and long-term phase (average follow-up 18 ± 12 months). In conclusion, Thera I and Kappa pacemakers exhibit excellent protection against interference produced by RF current. The functional integrity of the pacemakers and Capsure leads was observed in the acute and chronic phases. Thus, the implantation of these pacing systems prior to RF ablation of the AV junction can be recommended. [source]