Need For Ventricular Pacing Research Articles

Techniques for Cardiac Resynchronization Therapy in Patients with Congenital Heart Disease.

Cardiac resynchronization therapy (CRT) for congenital heart disease has shown promising suucess as an adjunct to medical therapy for heart failure. While cardiac conduction defects and need for ventricular pacing are common in congential heart disease, CRT indications, techniques and long term outcomes have not been well establaished. This is a review of the techniques nad short term outcomes of CRT for the following complex congenital heart disease conditions: single ventricle physiology, systemic right ventricle, and the subpulmonic right ventricle.

Electroanatomic mapping system guided His bundle pacemaker implantation: experience of the His bundle registry graz

Abstract Funding Acknowledgements Type of funding sources: None. Background Electric conduction disturbances are very common, however, patients in need for ventricular pacing may suffer from pacing-induced heart failure due to unphysiological pacing by the right ventricular lead. Conducting system pacing allows to overcome this common issue with a more physiologic approach, but real-life procedural data using this technology is scarce. Methods We report a single centre experience of the first 63 consecutive patients being implanted with a His-bundle-based pacemaker 09/2020-11/2022 per 3D-mapping guided implantation due to bradyarrhythmia, or for cardiac resynchronisation therapy in heart failure combined with a left-ventricular lead (HOT-CRT) ± a right ventricular defibrillator lead. The identification of the His-bundle-location was done with a 3D electroanatomic mapping system via an introducing sheath that is provided with electrodes at its tip. Results Mean age was 71 [18;87] years, 18/63 (29%) patients were female, mean baseline LVEF was 46±15%. Baseline ECG was captured before implantation: QRS width was 127±34ms, with typical LBBB in 19/63 (30%), typical RBBB in 5/63 (8%), alternating BBB in two patient (3%) and either no BBB or ventricular escape rhythm in 37/63 (59%). Indications for implantation were AV-block grade II-III in 31/63 (49%), primary prophylactic ICD indication in HFrEF in 18/63 (29%), atrial fibrillation with bradycardic conduction in 8/63 patients (13%), sick-sinus-syndrome in 4/63 (7%) and secondary prophylactic ICD indication in one patient (2%). In 57/63 (90,5%) a primary device was implanted, in 6/63 (9,5%) a pre-existent device was upgraded with a HB lead. Therefore, 23 dual-chamber-pacemaker, 5 single-chamber-pacemaker, 10 single-chamber CRT-P, 17 dual-chamber CRT-P, 4 single-chamber CRT-D, 4 dual-chamber CRT-D were implanted. In 63 patients his bundle pacing was attempted, while in 6/63 (9%) patients outside of this analysis the attempt was not successful, these patients were consecutively implanted with a non-HBP-device and therefor excluded from the further analysis. In the 63 patients included in this analysis with a primary successful pacing at the his-position, 5/63 (8%) his-bundle-leads dislocated within the first 48 hours, leading to a secondary success rate of 92%. There were two post-procedural pneumothorax that needed drainage, no major procedure-related complications occurred. Median skin-to skin procedure time was 111±47 minutes in his-bundle-device-implantation. The paced QRS width at the post-implantation follow up was 113±27ms with a change in QRS width of -15±39ms (+72; -92ms). The mean his-bundle sensing was 5,38±5,6mV and the mean threshold 1,1±0,86V over 1,0±0,5ms (0,4;1,5ms). The proportion of ventricular pacing was 75±36%. Conclusion Electroanatomic-guided His bundle pacing as a new innovative technic for physiological pacing is viable including high implantation success rate as well as electric impact, both regarding QRS width and pacing threshold.

Abstract 10530: Incidence and Electrocardiographic Predictors of Atrioventricular Conduction Recovery After Permanent Pacemaker Implantation in Transcatheter Aortic Valve Replacement

Background: High grade atrioventricular (AV) block (HGAVB) after transcatheter aortic valve replacement (TAVR) requiring permanent pacemaker implantation (PPM) is a well-established complication, but recovery of intrinsic AV conduction is not well studied. We assessed the incidence and electrocardiography (ECG) predictors of AV conduction recovery after PPM implantation post-TAVR. Methods: In this multicenter, retrospective study, consecutive patients undergoing TAVR between January 2015 to February 2019 were identified. All patients requiring PPM for HGAVB within 30 days after TAVR were included. Follow up ECGs, PPM checks, and clinic notes were reviewed to determine AV conduction recovery, defined as no need for ventricular pacing. Results: There were 533 TAVR patients, 443 with balloon expandable valves (BEV) and 90 with self-expanding valves (SEV). 5.1% of patients (n=27) required PPM for HGAVB, including 4.5% (n=20) from BEV group and 7.8% (n=7) from SEV group. Right bundle branch block (RBBB) was the most common baseline ECG finding (n=19). Mean time to PPM implant was 3.3±4.5 days. 11 patients received leadless and 16 received conventional pacemakers. At 6 months, 65% (n=13) of BEV group and none of SEV group had AV conduction recovery. BEV patients without AV conduction recovery had significantly longer baseline PR intervals compared to those with recovery (248±85 msec vs 169±22 msec; 95% CI 12.5-147.2; p=0.024). There were no significant differences in baseline QRS duration or presence of RBBB between those with and without AV conduction recovery. Conclusion: AV conduction recovery is more frequent after PPM implantation in TAVR patients receiving BEV (65%) compared to SEV (0%). Normal baseline PR intervals at baseline is associated with higher rate of AV conduction recovery among BEV patients. Temporary pacing with leadless pacemakers may be an alternative to conventional pacemakers in BEV patients without baseline first degree AV block.

Electroanatomic mapping system guided his bundle pacemaker implantation: experience of the his bundle registry graz

Abstract Funding Acknowledgements Type of funding sources: None. Background Patients with bradyarrhythmia in need for ventricular pacing may suffer from pacing-induced heart failure due to unphysiological right ventricular pacing. His bundle pacing (HBP) allows to overcome this common issue with a more physiologic approach but real-life procedural data using this technology is scarce. Methods We report a single centre experience of the first 44 consecutive patients being implanted with a His-bundle-based pacemaker 09/2020-11/2021 per 3D-mapping guided implantation due to different types of bradyarrhythmia, or for cardiac resynchronisation therapy in heart failure combined with a left-ventricular lead (HOT-CRT) ± a right ventricular defibrillator lead. The positioning of the His-bundle-lead was done by identifying the His-bundle-location with a 3D electroanatomic mapping system via an introducing sheath that is provided with electrodes at its tip. Results Mean age was 70 [16;86] years, 12/44 (27%) patients were female, mean baseline LVEF was 44±18%. Baseline ECG was captured: QRS width was 123±33ms, with typical LBBB in 14/44 (32%), typical RBBB in 4/44 (9%), alternating BBB in one patient (2%) and either no BBB or ventricular escape rhythm in 25/44 (57%). Indications for implantation were AV-block grade II-III in 19/44 (43%), primary prophylactic ICD indication in HFrEF in 13/44 (30%), atrial fibrillation with bradycardic conduction in 7/44 patients (16%), sick-sinus-syndrome in 4/44 (9%) and secondary prophylactic ICD indication in one patient (2%). In 41/44 (93%) a primary device was implanted, in 3/44 (7%) a pre-existent device was upgraded with a HB lead. Therefore, 14 dual-chamber-pacemaker, 5 single-chamber-pacemaker, 8 single-chamber CRT-P, 11 dual-chamber CRT-P, 4 single-chamber CRT-D, 2 dual-chamber CRT-D were implanted. In 50 patients HBP was attempted, while in 6/50 (12%) patients outside of this analysis the attempt was not successful, these patients were consecutively implanted with a non-HBP-device and therefor excluded from the further analysis. In the 44 patients included in this analysis with primary successful HBP, 4/44 (9%) his-bundle-leads dislocated within the first 48 hours, leading to a secondary success rate of 91%. There were two post-procedural pneumothorax that needed drainage, no major procedure-related complications occurred. Median skin-to skin procedure time was 109±50 minutes. The paced QRS width at the post-implantation follow up was 115±32ms with a change in QRS width of -10ms (+72;-92ms). When excluding the secondary lead dislocations and including only the successful HB paced QRS complexes, the paced QRS width was 105±30ms and the change in QRS width was -12±42ms. The mean his-bundle threshold was 1,2±1V over 0,5ms (0,5;1,5ms). The proportion of ventricular pacing was 69±38%. Conclusion Electroanatomic-guided His bundle pacing is feasible, with high implantation success rate and electric impact, both regarding QRS width and pacing threshold.

Transvenous electrical cardioversion of atrial fibrillation in horses: patient and procedural factors correlated with success and recurrence

Background: Transvenous electrical cardioversion (TVEC) is one of the main treatment options for atrial fibrillation (AF) in horses. Large-scale studies on factors affecting success and prognosis have primarily been performed in Standardbred populations. Objectives: To determine the factors affecting success, difficulty of TVEC and recurrence in a mainly Warmblood population. Study Design: Retrospective study. Methods: TVEC records of patients admitted for AF without severe echocardiographic abnormalities were studied. Patient and procedural factors for success rate and cumulative amount of energy (≤600J versus >600J) were determined using multiple logistic regression. A survival analysis was performed to determine risk factors for recurrence within one year after a first AF episode. Results: 231 TVEC procedures were included, with a 94.4% success rate and 34.3% recurrence rate. The depth of pulmonary artery catheter insertion was the only independent predictor for success (OR 1.143, 95%CI [1.005-1.300], P=0.041). Catheter type (OR 0.257, 95%CI [0.109-0.606], P=0.002), height at the withers (OR 1.087, 95%CI [1.021-1.157], P=0.009) and previous AF episode (OR 2.909, 95%CI [1.043-8.112], P=0.041) were significantly correlated with cumulative amount of energy. Significant risk factors for recurrence were male sex (HR 6.648, 95%CI [2.591-17.060], P<0.001), immediate AF recurrence during TVEC (HR 6.232, 95%CI [1.627-23.877], P=0.007), AF duration (HR 1.002, 95%CI [1.0003-1.003], P=0.017) and need for ventricular pacing (HR 3.455, 95%CI [1.005-11.879], P=0.049). Main Limitations: The retrospective nature of the study resulted in missing values. Conclusion: TVEC success and difficulty depend both on patient factors and procedural factors such as catheter insertion depth and catheter type.

Eligibility for subcutaneous implantable cardioverter-defibrillator in adults with congenital heart disease.

AimsPatients with adult congenital heart disease (ACHD) carry an increased risk for sudden cardiac death. Implantable cardioverter‐defibrillator (ICD) therapy may be challenging in these patients due to anatomical barriers, repeated cardiac surgery, or complicated transvenous access. Thus, the subcutaneous ICD (S‐ICD) can be a promising alternative in this patient population. Patients with ACHD show significant electrocardiogram (ECG) abnormalities, which could affect S‐ICD sensing because it depends on surface ECG.Methods and resultsOne hundred patients with ACHD were screened for S‐ICD eligibility. Standard ECG‐based screening test and automated S‐ICD screening test were performed in all patients. Sixty‐six patients (66%) were male. Underlying congenital heart disease (CHD) was mainly CHD of great complexity (71%) and moderate complexity (29%), including repaired tetralogy of Fallot (20%), which was the most common entity. Thirty‐seven patients (37%) already had a pacemaker (23%) or ICD (14%) implanted. Automated screening test identified 83 patients (83%) eligible for S‐ICD implantation in either left parasternal position (78%) or right parasternal position (75%). Absence of sinus rhythm, QRS duration, and a paced QRS complex were associated with S‐ICD screening failure in univariate analysis. Receiver operating characteristic curve and multivariate analysis revealed a QRS duration ≥148 ms as the only independent predictor for S‐ICD screening failure.ConclusionsPatients with ACHD show satisfactory eligibility rates (83%) for S‐ICD implantation utilizing the automated screening test, including patients with CHD of high complexity. S‐ICD therapy should be considered with caution in ACHD patients with a QRS duration ≥148 ms and/or need for ventricular pacing.

Within-patient comparison of His-bundle pacing, right ventricular pacing, and right ventricular pacing avoidance algorithms in patients with PR prolongation: Acute hemodynamic study.

A prolonged PR interval may adversely affect ventricular filling and, therefore, cardiac function. AV delay can be corrected using right ventricular pacing (RVP), but this induces ventricular dyssynchrony, itself harmful. Therefore, in intermittent heart block, pacing avoidance algorithms are often implemented. We tested His-bundle pacing (HBP) as an alternative. Outpatients with a long PR interval (>200 ms) and intermittent need for ventricular pacing were recruited. We measured within-patient differences in high-precision hemodynamics between AV-optimized RVP and HBP, as well as a pacing avoidance algorithm (Managed Ventricular Pacing [MVP]). We recruited 18 patients. Mean left ventricular ejection fraction was 44.3 ± 9%. Mean intrinsic PR interval was 266 ± 42 ms and QRS duration was 123 ± 29 ms. RVP lengthened QRS duration (+54 ms, 95% CI 42-67 ms, p < .0001) while HBP delivered a shorter QRS duration than RVP (-56 ms, 95% CI -67 to -46 ms, p < .0001). HBP did not increase QRS duration (-2 ms, 95% CI -8 to 13 ms, p = .6). HBP improved acute systolic blood pressure by mean of 5.0 mmHg (95% CI 2.8-7.1 mmHg, p < .0001) compared to RVP and by 3.5 mmHg (95% CI 1.9-5.0 mmHg, p = .0002) compared to the pacing avoidance algorithm. There was no significant difference in hemodynamics between RVP and ventricular pacing avoidance (p = .055). HBP provides better acute cardiac function than pacing avoidance algorithms and RVP, in patients with prolonged PR intervals. HBP allows normalization of prolonged AV delays (unlike pacing avoidance) and does not cause ventricular dyssynchrony (unlike RVP). Clinical trials may be justified to assess whether these acute improvements translate into longer term clinical benefits in patients with bradycardia indications for pacing.

Need for pacing in patients who qualify for an implantable cardioverter‐defibrillator: Clinical implications for the subcutaneous ICD

BackgroundImplantation of the subcutaneous implantable cardioverter‐defibrillator (S‐ICD) is spreading and has been shown to be safe and effective; however, it does not provide brady‐pacing. Currently, data on the need for brady‐pacing and cardiac resynchronization therapy (CRT) implantation in patients with ICD indication are limited.MethodsThe Multicenter Automatic Defibrillator Implantation Trial (MADIT)‐II enrolled post‐MI patients with reduced ejection fraction (EF ≤ 35%), randomized to either an implantable cardioverter‐defibrillator (ICD) or conventional medical therapy. Kaplan–Meier analyses and multivariate Cox models were performed to assess the incidence and predictors of pacemaker (PM), or CRT implantation in the conventional arm of MADIT‐II, after excluding 32 patients (6.5%) with a previously implanted PM.ResultsDuring the median follow‐up of 20 months, 24 of 458 patients (5.2%) were implanted with a PM or a CRT (19 PM, 5 CRT). Symptomatic sinus bradycardia was the primary indication for PM implantation (n = 9, 37%), followed by AV block (n = 5, 21%), tachy‐brady syndrome (n = 4, 17%), and carotid sinus hypersensitivity (n = 1, 4%). Baseline PR interval >200 ms (HR = 3.07, 95% CI: 1.24–7.57, p = .02), and CABG before enrollment (HR = 6.88, 95% CI: 1.58–29.84, p = .01) predicted subsequent PM/CRT implantation. Patients with PM/CRT implantation had a significantly higher risk for heart failure (HR = 2.67, 95% CI = 1.38–5.14, p = .003), but no increased mortality risk (HR = 1.06, 95% CI = 0.46–2.46, p = .89).ConclusionThe short‐term need for ventricular pacing or CRT implantation in patients with MADIT‐II ICD indication was low, especially in those with a normal baseline PR interval, and such patients are appropriate candidates for the subcutaneous ICD.

Ventricular rate stabilization for treatment of recurrent VT.

Apatient with ischaemic cardiomyopathy received asecondary prevention VVI implantable cardioverter-defibrillator (ICD) after an episode of sustained ventricular tachycardia (VT). Because of recurrent VTs transmitted via CareLink, medical therapy was optimized and VT ablation was performed. Subsequently, afast VT with atypical short-long-short initiation developed. In addition, there was an increasing need for ventricular pacing due to sinus bradycardia. This new type of VT could be successfully dealt with by upgrading to DDD ICD and activating the Ventricular Rate Stabilization algorithm.

56-38: Pacemaker implantation after cardiac surgery: are we implanting to soon?

Purpose of the study: Bradyarrhythmias occuring during or shortly after cardiac surgery are important indications for permanent pacing. The aim of the study was to find out whether patients after cardiac surgery are appropriately indicated for pacemaker implantation, i.e. if they still need pacing in the long term follow-up. Method used: This was a retrospective study of patients who underwent cardiac surgery and were indicated for dual chamber pacemaker in the perioperative period between January 2012 and December 2014. Adequate pacing indication was defined as need for ventricular pacing in more than 5 % of the time during the period from implantation to first pacemaker control in patients with atrioventricular block (AVB) or more than 5% atrial pacing during the same time period in case of sinus node dysfunction (SND). Summary of results: Overall, 27 patients were included, 17 (63%) with AVB and 11 with (41%) SND. The mean time of the period from implantation to first pacemaker control was 98 ± 42 days. In the AVB group, 3 patients (17.6%) were paced in less than 5%. In SND group it was only 1. Time from surgery to pacemaker implantation was not different for the appropriate implanted patients compared to the inappropriate implanted ones (median 8[range 2–83] vs. 9[6–17], p = NS). Conclusion: Nearly 20% of AVB patients implanted in the perioperative period recovered atrioventricular conduction during the observed period, showing that improvement can occur later than in guidelines mentioned 7 days after surgery. Percentage of patients that don't require pacemaker could be even higher due to unsuitable pacemaker programming in some patients (e.g. too high base rate or not activated preference of atrial pacing). Implantation of permanent pacemakers in the perioperative period due to AVB might be premature in significant proportion of the patients.

Bachmann's Bundle Pacing not Only Improves Interatrial Conduction but Also Reduces the Need for Ventricular Pacing.

Patients treated for sick sinus syndrome may have interatrial conduction disorder leading to atrial fibrillation. This study was aimed to assess the influence of the atrial pacing site on interatrial and atrioventricular conduction as well as the percentage of ventricular pacing in patients with sick sinus syndrome implanted with atrioventricular pacemaker. The study population: 96 patients (58 females, 38 males) aged 74.1 ± 11.8 years were divided in two groups: Group 1 (n = 44) with right atrial appendage pacing and group 2 (n = 52) with Bachmann's area pacing. We assessed the differences in atrioventricular conduction in sinus rhythm and atrial 60 and 90 bpm pacing, P-wave duration and percentage of ventricular pacing. No differences in baseline P-wave duration in sinus rhythm between the groups (102.4 ± 17 ms vs. 104.1 ± 26 ms, p = ns.) were noted. Atrial pacing 60 bpm resulted in longer P-wave in group 1 vs. group 2 (138.3 ± 21 vs. 106.1 ± 15 ms, p < 0.01). The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with right atrial appendage vs. Bachmann's pacing (44.1 ± 17 vs. 9.2 ± 7 ms p < 0.01 and 69.2 ± 31 vs. 21.4 ± 12 ms p < 0.05, respectively). The percentage of ventricular pacing was higher in group 1 (21 vs. 4%, p < 0.01). Bachmann's bundle pacing decreases interatrial and atrioventricular conduction delay. Moreover, the frequency-dependent atrioventricular conduction lengthening is much less pronounced during Bachmann's bundle pacing. Right atrial appendage pacing in sick sinus syndrome patients promotes a higher percentage of ventricular pacing.

Pacemaker implantation and need for ventricular pacing during follow-up after transcatheter aortic valve implantation.

Pacemaker implantation and need for ventricular pacing during follow-up after transcatheter aortic valve implantation.

Pacemaker implantation and need for ventricular pacing during follow-up after transcatheter aortic valve implantation.

To categorize indications of permanent pacemaker (PPM) implantation after transcatheter aortic valve implantation (TAVI), to determine predictors for conduction disturbances and to quantify the need for ventricular pacing during follow-up. We studied 97 patients (median age 83 years, 58% female) undergoing TAVI using the Medtronic CoreValve Revalving System (MCRS; Medtronic Inc., Minneapolis, MN, USA) or Edwards-Sapien Valve (Edwards Lifesciences, Irvine, CA, USA). During follow-up, no need for ventricular pacing was defined as <1% ventricular pacing and intrinsic 1:1 atrioventricular (AV) conduction. In the 35 patients (36.1%) undergoing PPM implantation three indication categories were identified: (1) high-grade AV block (Mobitz 2 or higher), (2) new-onset left bundle branch block (LBBB) with a prolonged PR interval, and (3) new-onset LBBB. The only independent predictors of high-grade AV block were the use of MCRS (odds ratio [OR] 79.25; 95% confidence interval [CI] 4.57-1373.31) and the presence of preprocedural right bundle branch block (OR 81.95; 95% 95% CI 8.72-770.46). Whereas high-grade AV block resolved only in 17% of cases, none of the patients receiving a PPM due to LBBB with or without PR prolongation required ventricular pacing during follow-up. Our findings justify early PPM implantation in patients with high-grade AV block and may suggest a more conservative approach to PPM implantation in patients with new-onset LBBB after TAVI.

Bachmann's bundle pacing not only improves interatrial conduction but also reduces the need for ventricular pacing

Background: Patients treated for sick sinus syndrome may have interatrial conduction disorder, what often leads to atrial fibrillation. Moreover, up to 20% of them have atrioventricular conduction delay which worsens over time and is responsible for the need of ventricular pacing. Implantation of atrial lead in right atrium appendage (RAA) is the reason for longer interatrial and atrioventricular conduction time even in patients without prior disorders. Purpose: The aim of this study was to assess influence of atrial pacing site on interatrial and atrioventricular conduction and the percentage of ventricular pacing in population with SSS implanted with DDD pacemaker. Methods: The study group consisted of 107 patients (64 F, 43 M) aged 71,2±18,7 years. Patients were divided in two groups: group I (n=51) with RAA pacing, group II (n= 56) with Bachmann's area pacing. Differences in atrioventricular conduction in sinus rhythm and AAI 60 and 90/min pacing were assessed. Also P wave width at sinus rhythm and during atrial pacing as well as percentage of ventricular stimulation were compared. P wave morphology was studied in surface ECG leads I and II. Results: There were no differences in baseline P wave duration in sinus rhythm between the groups (99.7±16 ms vs 103.0±28 ms, p=n.s.). Atrial pacing 60 bpm revealed longer P wave duration with atrial lead location in RAA in comparison to Bachmann's bundle region (141.1±24.3 vs 107.2±14.2 ms, p<0.01). In group II the P wave morphology was more comparable with sinus P wave. The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with RAA vs. Bachmann's pacing (42.1±16 vs 8±7 ms p<0.01 and 68±32 vs 22±11 ms p<0.005, respectively). The percentage of ventricular pacing was higher in group I (19±1 vs 3±3%, p<0,01). Conclusions: 1. Right atrium appendage pacing in SSS pts promotes atrioventricular conduction disorder which results in higher percentage of ventricular pacing in DDD mode. 2.The Bachmann's bundle region pacing of right atrium results in less pronounced interatrial and atrioventricular conduction delay.

Prevalence and Predictors of Off-Label Use of Cardiac Resynchronization Therapy in Patients Enrolled in the National Cardiovascular Data Registry Implantable Cardiac-Defibrillator Registry

The purpose of the study was to define the extent and nature of cardiac resynchronization therapy (CRT) device usage outside consensus guidelines using national data. Recent literature has shown that the application of CRT in clinical practice frequently does not adhere to evidence-based consensus guidelines. Factors underlying these practices have not been fully explored. From the National Cardiovascular Data Registry's Implantable Cardiac-Defibrillator Registry, we defined a cohort of 45,392 cardiac resynchronization therapy-defibrillator (CRT-D) implants between January 2006 and June 2008 with a primary prevention indication. We defined "off-label" implants as those in which the ejection fraction was >35%, the New York Heart Association functional class was below III, or the QRS interval duration was <120 ms in the absence of a documented need for ventricular pacing. The relationships between patient, implanting physician, and hospital characteristics with off-label use were explored with multivariable hierarchical logistic regression models. Overall, 23.7% of devices were placed without meeting all 3 implant criteria, most often due to New York Heart Association functional class below III (13.1% of implants) or QRS interval duration <120 ms (12.0%). Atrial fibrillation/flutter, previous percutaneous coronary intervention, and the performance of an electrophysiology study before implant were independently associated with increased odds of off-label use, whereas diabetes mellitus, increasing age, and female sex were associated with decreased odds. Physician training and insurance payer were weakly associated with the likelihood of off-label use. Nearly 1 in 4 patients receiving CRT devices in the study time frame did not meet guideline-based indications. Given the evolving evidence base supporting the use of CRT, these practices require careful scrutiny.

Guillain-Barré Syndrome with asystole requiring permanent pacemaker: a case report

IntroductionGuillain-Barré syndrome is an acute demyelinating disorder of the peripheral nervous system that results from an aberrant immune response directed at peripheral nerves. Autonomic abnormalities in Guillain-Barré syndrome are usually transient and reversible. We present a case of Guillain-Barré syndrome requiring a permanent pacemaker in view of persistent symptomatic bradyarrhythmia.Case PresentationAn 18-year-old Caucasian female presented with bilateral lower limb paraesthesias followed by bilateral progressive leg weakness and difficulty in walking. She reported an episode of an upper respiratory tract infection 3 weeks prior to the onset of her neurological symptoms. Diagnosis of Guillain-Barré syndrome was considered and a lumbar puncture was performed. Cerebrospinal fluid revealed albuminocytologic dissociation (increased protein but normal white blood cell count) suggestive of Guillain-Barré syndrome and hence an intravenous immunoglobulin G infusion was started. Within 48 hours, she progressed to complete flaccid quadriparesis with involvement of respiratory muscles requiring mechanical ventilatory support. Whist in the intensive care unit, she developed multiple episodes of bradycardia and asystole requiring a temporary pacemaker. In view of the persistent requirement for the temporary pacemaker for more than 5 days, she received a permanent pacemaker. She returned for follow-up three months after discharge with an intermittent need for ventricular pacing.ConclusionGuillain-Barré syndrome can result in permanent damage to the cardiac conduction system. Patients with multiple episodes of bradycardia and asystole in the setting of Guillain-Barré syndrome should be evaluated and considered as potential candidates for permanent pacemaker implantation.

Efficacy of three-channel ambulatory electrocardiographic monitoring for the detection of myocardial ischemia

The recognition of silent myocardial ischemia (SMI) has been demonstrated to have important clinical relevance. Two-channel ambulatory (Holter) electrocardiographic recording is a commonly utilized method for detecting transient electrocardiographic ST segment changes representative of SMI. It has been suggested that the analysis of two channels alone may not adequately detect SMI. We therefore evaluated the diagnostic yield of three channels using a three-channel electrocardiographic monitoring device in 46 consecutive patients (age 61 ± 9 years) undergoing percutaneous transluminal coronary angioplasty of an isolated single-vessel stenosis. Modified bipotar chest leads V 2, V 5, and AVF (CM-V 2, CM-V 5, and CS-AVF) were utilized for analysis. The percent detection of ST segment changes from various combinations of two-lead recordings were compared to the total three leads, and an absolute transient ST segment shift (STSS) of ≥ 1 mm during balloon inflation was considered as evidence of myocardial ischemia. One patient was excluded because of the need for ventricular pacing during balloon inflation. A total of 33 of 45 patients had STSS in all three leads (percent detection = 73%), while 32 (71%) had STSS in the two-lead grouping with the highest diagnostic yield (CM-V 2/CM-V 5; p = ns). Of the various two-lead combinations studied, leads CM-V 2 and CM-V 5 provided the best lead set overall for the detection of ischemic STSS. Three-channel ambulatory electrocardiographic recording only marginally improves upon the detection of ischemia when compared with standard ( CM-V 2 CM-V 5 or CM-V 5 CS-AVF ) two-channel ambulatory electrocardiographic recordings.

The Paceport catheter: a new pacemaker system introduced through a Swan-Ganz catheter.

We describe a new stainless steel, teflon-coated 2.4 F pacemaker wire with a flexible tip that can be introduced through an extra lumen of a specially designed 7.5 F Swan-Ganz catheter. The extra lumen opens at 19 cm from the tip of the catheter; this opening can be positioned in the right ventricular cavity. The pacemaker wire can be introduced at the time of insertion of the Swan-Ganz catheter or later when the need for ventricular pacing arises. The Paceport catheter was tested in 23 patients. Satisfactory ventricular pacing was achieved in 19 patients at thresholds between 0.5 and 4.0 mA (median 2.0 mA). The threshold increased by 1 mA during long-term pacing (8-24 hr). Attempts to use the pacemaker were abandoned when short runs of ventricular tachycardia developed upon introduction, while an exceptionally high threshold was observed in another patient. The Paceport system is recommended for patients who require hemodynamic monitoring and urgent ventricular pacing.

Special Considerations in Ventricular Pacing in Patients with Tricuspid Valve Disease

In patients who have undergone prosthetic tricuspid valve replacement or tricuspid an-nuloplasty and in whom the pericardial space is obliterated by adhesions from previous operations, the need for ventricular pacing may be met by lead placement in the venous tributaries of the coronary veins. This approach avoids compromise of prosthetic tricuspid valve function and injury to biopros-thetic valves and natural valves repaired by annulo-plasty. Although acute stimulation thresholds are slightly higher than those for short-term endocardial implants, stable long-term ventricular pacing has been observed in patients reported in the literature in whom such lead placement was inadvertent and in the 2 patients in the present paper in whom such replacement was deliberate. This method appears to be a safe alternative to standard ventricular pacing techniques under the special circumstances reported here.