Electrical activation in the coronary sinus branches as a guide to cardiac resynchronisation therapy: rationale for a coordinate system.

BACKGROUND: For successful cardiac resynchronisation therapy (CRT) a spatial and electrical separation of right and left ventricular electrodes is essential. The spatial distribution of electrical delays within the coronary sinus (CS) tributaries has not yet been identified. OBJECTIVE: Electrical delays within the CS are described during sinus rhythm (SR) and right ventricular pacing (RVP). A coordinate system grading the mitral ring from 0° to 360° and three vertical segments is proposed to define the lead positions irrespective of individual CS branch orientation. METHODS: In 13 patients undergoing implantation of a CRT device 6±2.5, (median 5) lead positions within the CS were mapped during SR and RVP. The delay to the onset and the peak of the local signal was measured from the earliest QRS activation or the pacing spike. Fluoroscopic positions were compared to localizations on a nonfluoroscopic electrode imaging system. RESULTS: During SR, electrical delays in the CS were inhomogenous in patients with or without left bundle branch block (LBBB). During RVP, the delays increased by 44±32 ms (signal onset from 36±33 ms to 95±30 ms; p<0.001, signal peak from 105±44 ms to 156±30 ms; p<0.001). The activation pattern during RVP was homogeneous and predictable by taking the grading on the CS ring into account: (% QRS) = 78-0.002 (grade-162)(2), p<0.0001. This indicates that 78% of the QRS duration can be expected as a maximum peak delay at 162° on the CS ring. CONCLUSION: Electrical delays within the CS vary during SR, but prolong and become predictable during RVP. A coordinate system helps predicting the local delays and facilitates interindividual comparison of lead positions irrespective of CS branch anatomy.

Gold-coated pacemaker implantation after allergic reactions to pacemaker compounds.

An 86-year-old man underwent pacemaker implantation for symptomatic atrio-ventricular block grade 2 Mobitz II. The patient suffered repeated admissions for iterative sterile wound necrosis, leading to two generator re-implantations. No bacterial infection was detected in the microbiological screening tests. The skin patch testing to titanium was negative. Nevertheless, we decided to remove the pacemaker system and to implant a gold-plated generator with polyurethane leads. Since then, there has been no recurrence of wound complications. Gold-plated generator and polyurethane leads are effective in treating allergic reactions to pacemaker system components in selected cases. Negative skin patch testing to titanium does not exclude allergic reaction to this pacemaker component.

Epicardial and pleural lead ICD systems in children and adolescents maintain functionality over 5 years.

AIMS: The optimal implantable cardioverter defibrillator (ICD) system implant technique has not yet been defined in young patients and those with congenital heart disease (CHD). We describe our 5-year experience with epicardial pacing/sensing leads secured on the left cardiac chambers and a pleural defibrillation lead insertion along the third intercostal space. METHODS AND RESULTS: Implantable cardioverter defibrillator systems were implanted in 15 children and adolescents (age: 2.9-20.0 years) for primary (n = 11) or secondary (n = 4) prevention. Underlying CHD were hypertrophic (n = 10) or dilative cardiomyopathies (n = 2), primary electrical diseases (n = 2), and transposition of the great arteries (n = 1). Devices were placed in the rectus sheath (n = 5), or within the diaphragm (n = 10). Median defibrillation threshold at implant was 15 J (range: 10-25). During 5 years of follow-up (median: 22 months), nine appropriate and two inappropriate ICD discharges occurred. Four system revisions were required due to device recall, pleural lead dislodgement, epicardial lead fracture, and insulation break. Twelve months after the implantation, defibrillation threshold testing demonstrated stable thresholds of

A 12-year experience of bipolar steroid-eluting epicardial pacing leads in children.

BACKGROUND: Cardiovascular abnormalities and small vascular size may preclude transvenous pacing and necessitate epicardial lead implantation. This study evaluates the performance of steroid-eluting, bipolar epicardial pacing leads. METHODS: We prospectively enrolled 114 children with 239 atrial and ventricular bipolar epicardial leads (Medtronic CapSure 10366 or 4968, Minneapolis, MN), followed up to 12.2 years (median, 3.2). Lead data were obtained at implant and at semi-annual visits. Analysis was done for left or right atrial and ventricular leads. RESULTS: Median atrial and ventricular pacing thresholds remained below 1.2 V at 0.5 ms. Thresholds did not differ between pacing sites: left atrial, 0.82 V at 0.5 ms; right atrial, 0.74 V at 0.5 ms (p = 0.85); and left ventricular, 0.96 V at 0.5 ms; right ventricular, 0.94 V at 0.5 ms (p = 0.65). Sensing demonstrated no difference for atrial leads, at left atrial, 3.4 mV; and right atrial, 2.9 mV (p = 0.12), but there was superiority of left over right ventricular leads (11.2 vs 7.7 mV, p = 0.002). During follow-up, the 239 atrial and ventricular leads experienced 19 (8%) lead failures. Lead survival at 2 and 5 years was 99% and 94% for atrial leads and 96% and 85% for ventricular leads, respectively. CONCLUSIONS: Bipolar steroid-eluting epicardial leads demonstrate excellent sensing characteristics and persistent low median pacing thresholds below 1.2 V at 0.5 ms in children during up to 12 years follow-up. Considering growing and active patients with most having congenital heart disease, the lead survival of 85% to 94% at 5 years is favorable. Subanalysis shows superior sensing for left ventricular leads. Bipolar steroid-eluting leads provide an alternative approach for permanent pacing and may also be considered for left atrial and ventricular pacing, resynchronization, or defibrillator therapy.

Initial experience with implantable cardioverter defibrillator systems using epicardial and pleural electrodes in pediatric patients.

Implantable cardioverter defibrillators in children have proven to be an effective therapy for life-threatening ventricular arrhythmias. The optimal electrode and device placement for implantable cardioverter defibrillator therapy in children is still controversial. We describe our initial experience after epicardial and pleural electrode insertion with abdominal or intrathoracic device placement in 8 children.

Long-term follow-up after pacemaker implantation in neonates and infants.

BACKGROUND: Pacemaker (PM) system implantation in neonates and infants is often complicated by hemodynamic instability, small vessel size, and abnormal cardiovascular anatomy. Thus, an open surgical approach for epicardial lead insertion is often required. We assessed the long-term outcomes after epicardial PM implantation in this age group. METHODS: Between 1992 and 2004, 22 consecutive patients underwent PM implantation within the first year of life. Bipolar steroid-eluting epicardial leads (Medtronic CapSure Epi 10366 and 4968) were inserted through median sternotomy, the sybxyphoid approach, or thoracotomy, and connected to various pulse generators. RESULTS: Pacemakers were implanted at a median age of 35 days (range, 1 to 300). Intracardiac anatomy was abnormal in 17 patients. Indications for PM therapy were heart block in 18 patients and sinus node dysfunction in 4 patients. During a median follow-up of 4.6 years (range, 4 days to 12.8 years), 7 devices were replaced owing to end of battery life (n = 6) or elective device repositioning (n = 1), at a median of 4.1 years (range, 1 to 7.8). One dislodged ventricular lead and 2 atrial lead sensing failures were observed. Sensing, pacing thresholds, and lead impedances showed good implant and stable follow-up values. CONCLUSIONS: Pacemaker-associated morbidity is low. Pacemaker system complications with epicardial leads are rare. Battery life is relatively shorter compared with children and adults because of the fast heart rate and complete PM dependency in most of these children. Even for neonates and infants, modern pacemaker therapy is feasible, safe, and effective.

Dual chamber epicardial pacing for the failing atriopulmonary Fontan patient.

BACKGROUND: The atriopulmonary Fontan circulation leads to arrhythmias, heart failure, or protein-losing enteropathy, eventually requiring conversion. In hesitant patients, we evaluated the effect of dual chamber pacing as a time-buying measure. METHODS: Between 1997 and 2004, 9 patients (aged, 6 to 18 years) with an atriopulmonary Fontan connection and sinus node dysfunction received dual chamber epicardial pacemaker systems. Indications included refractory arrhythmias (n = 5), protein-losing enteropathy (n = 2), heart failure with effusions (n = 1), and exercise intolerance (n = 2). Data were compared between hospital discharge after pacemaker implantation and last follow-up. RESULTS: There was no mortality or morbidity. At a follow-up of 3.3 +/- 1.0 years, lead survival was 100%. Both atrial (impedance = 683 +/- 40 Ohm; threshold = 0.8 +/- 0.1 V at 0.5 ms; sensing P waves = 3.3 +/- 0.8 mV) and ventricular (impedance = 630 +/- 68 Ohm; threshold = 1.3 +/- 0.3 V at 0.5 ms; sensing R waves = 8.7 +/- 2.5 mV) leads retained satisfactory pacing characteristics at last control, better than those at discharge. Arrhythmias subsided in all instances and no longer required medication in 3 patients. Protein-losing enteropathy improved temporarily in 1 patient and disappeared in another. Exercise intolerance diminished, and heart failure was controlled. CONCLUSIONS: Although most atriopulmonary Fontan circulations will need conversion with arrhythmia surgery, patients may delay out of fear. Dual chamber pacing improves single ventricle hemodynamics and can help decompensated Fontan patients. In a multiple-redo setting, a left lateral thoracotomy provides safe access and allows for quantitatively reliable and durable epicardial pacing.

Left heart atrial and ventricular epicardial pacing through a left lateral thoracotomy in children: a safe approach with excellent functional and cosmetic results.

OBJECTIVE: Left heart atrial and ventricular epicardial pacing through a left lateral thoracotomy is an alternative approach for lead insertion in children, avoiding venous access complications and right ventricular stimulation, without compromising sporting or musical activities. We analyzed the survival and performance of left atrial and left ventricular epicardial pacing leads, and present mid-term follow-up data. METHODS: Seventy-five bipolar steroid eluting pacing leads (Medtronic CapSure Epi 4968) were implanted in 41 children, aged 8.6+5.1 years. Pacing systems included 34 DDDR and 7 VVIR. Pacing leads were inserted through a muscle-sparing left lateral thoracotomy, and sutured to the left atrial appendage or atrium, and to the left ventricle. The generators were buried behind the abdominal muscles or between the thoracic muscle layers. Congenital heart disease with previous cardiac surgery was present in 25 children. Indications for pacing were post-operative heart block (n=14), sinus node disease (n=13), congenital heart block (n=9), and various (n=5). Threshold values and measured data were obtained at 6-month intervals. The mean follow-up was 3.8+2.9 years. RESULTS: There was no mortality or major morbidity, with excellent functional and cosmetic results. Lead survival was 94 and 86% for atrial leads, and 97 and 86% for ventricular leads, at 1 and 5 years, respectively. There were five reoperations for lead fracture (n=2), insulation break (n=1), oversensing (n=1), and infection (n=1). Device reprogramming was required in three instances. In the absence of acute lead failure, mid-term follow-up shows very satisfactory and stable lead performance. CONCLUSIONS: Left heart atrial and ventricular epicardial pacing leads inserted through a left lateral thoracotomy demonstrate a high probability of survival, with favorable pacing characteristics, and optimal sensing thresholds at mid-term follow-up. Epicardial left heart pacing is reliable, and easy access can be achieved through a cosmetic and functional muscle-sparing left lateral thoracotomy.