Efficacy of prophylactic epicardial pacing leads in children and young adults

Background

Epicardial pacemakers are often required in children and young adults who cannot undergo a transvenous system because of patient size, vascular barriers, or significant residual intracardiac shunts. Prophylactic epicardial pacing leads, placed at the time of concomitant congenital heart surgery, may reduce a late thoracotomy or sternotomy. The efficacy of prophylactic epicardial leads in the pediatric population is unknown.

Methods

A retrospective review of the cardiovascular surgery and pacemaker databases at The Children's Hospital of Philadelphia identified all patients less than or equal to 21 years of age, who underwent placement of an epicardial pacing lead between January 1, 1990 and December 31, 2002. Prophylactic epicardial pacing leads placed at the time of a concomitant congenital heart procedure were compared to standard epicardial leads that were connected to a simultaneous programable generator. Pacing and sensing threshold data were obtained in prophylactic epicardial leads at the time of lead retrieval and 6 month follow-up and compared to standard epicardial pacing leads.

Results

Twenty-two (13 ventricular, 9 atrial) prophylactic epicardial pacing leads were retrieved in 13 patients at a median of 252 days (7 days to 3.98 years) from the time of initial implant and compared to 256 (164 ventricular, 92 atrial) standard epicardial leads placed in 142 patients. Nineteen (86%) prophylactic epicardial leads had acceptable pacing and sensing thresholds at lead retrieval. Only 1 patient with atrial and ventricular leads had poor pacing and sensing at retrieval and required a redo-sternotomy for placement of new atrial and ventricular epicardial pacing leads. For the remaining atrial (n = 7) and ventricular (n = 12) prophylactic epicardial leads, there was no significant difference in pacing (atrial, 1.59 ± 1.1 μJ; ventricular, 1.98 ± 1.9 μJ) or sensing (atrial, 3.6 ± 1.8 mV; ventricular, 13.8 ± 4.4 mV) compared to standard pacing (atrial, 2.1 ± 1.8 μJ; ventricular, 1.9 ± 3.4 μJ) and sensing (atrial, 3.3 ± 1.7 mV; ventricular, 11.3 ± 5.3 mV) epicardial leads. Six-month follow-up pacing and sensing thresholds were not significantly different between the prophylactic and standard epicardial pacing leads.

Conclusions

Prophylactic epicardial pacing leads can be successfully placed and retrieved in a subset of children and young adults who will likely require pacing at a later date. Prophylactic leads have comparable pacing and sensing qualities at lead retrieval and short-term follow-up compared to standard epicardial leads. Consideration for prophylactic epicardial pacing leads will likely reduce the need for a late thoracotomy or sternotomy.     

Comparison of left and right atrial epicardial pacing in patients with congenital heart disease

Background. Complex congenital heart disease (CHD) often necessitates the use of epicardial pacing. Adequate right atrial (RA) sensing and pacing thresholds are often difficult to obtain due to suture line scarring and RA dilatation. The purpose of this study was to evaluate the placement of left atrial (LA) epicardial leads in children.

Methods. Patient demographics, pacing, and sensing data of atrial pacing systems implanted between January 1994 and January 1997 were collected.

Results. Forty-nine pacing systems were implanted: 14 LA epicardial, 19 RA epicardial, and 16 transvenous in the right atrium. Lead impedance, current, and energy were similar in the two epicardial groups throughout the study. Energy thresholds (ET) were lower in the LA than RA at 6 months, and 1 and 2 years (p < 0.05). Analysis of post-Fontan patients performed alone revealed a lower ET in the LA as compared with the RA. Pacing and sensing parameters from transvenous leads are presented for relative comparison.

Conclusions. Transvenous leads are most efficient but often contraindicated in complex CHD. LA leads offer lower energy thresholds than RA leads with similar sensing parameters.     

VATS-guided epicardial pacemaker implantation

Background: In neonates and infants epicardial stimulation may be preferred to endocardial stimulation because of growth-associated lead problems and the risk of vascular complications associated with transvenous electrodes. This study analyzes the feasibility of atrioventricular implantation of a new epicardial lead using the video-assisted thoracic surgical (VATS) technique in an animal model. Methods: Bipolar steroid-eluting epicardial leads were implanted in seven young white pigs. In five animals bipolar atrial and ventricular pacing leads (n= 10) were inserted and fixed by the VATS technique, while two animals served as controls and underwent implantation through anterolateral thoracotomy. Surgical feasibility, pacing, and sensing thresholds of the leads as well as hemodynamic parameters during pacing were studied. Histological changes beneath the electrodes were evaluated 1 week after the implantation. Results: All animals survived the pacemaker lead implantation. One animal which underwent thoracotomy died because of irreversible ventricular fibrillation induced by rapid ventricular pacing. One animal in the VATS group exhibited intraoperative herniation of the heart through the pericardial window. All animals with left-sided VATS implantations demonstrated good individual pacing and sensing threshold values. The mean cardiac output was 1.6 times higher during AAI-mode pacing as compared to VVI-mode pacing at a heart rate of 140/min. One animal died postoperatively due to respiratory failure. No displacements of the pacemaker leads were observed in the survivors. Conclusion: While VATS-guided implantation of epicardial, atrial, and ventricular leads is feasible, technical improvements of the system are mandatory for safe clinical application. Received: 14 October 1996/Accepted: 14 April 1997     

A comparison of steroid-eluting epicardial versus transvenous pacing leads in children

OBJECTIVE: To evaluate the acute and chronic performance of steroid-eluting (SE) epicardial (EPI) pacing leads as compared to SE transvenous (TV) pacing leads in children. METHODS: From 1989 through 1997, 55 children with congenital heart disease received a total of 85 SE pacing leads, of which 38 were EPI and 47 TV. The mean age of children receiving EPI leads was younger than those receiving TV leads (7.7 months vs 15.1 years, p = 0.001), and they had shorter follow-up (17.2 months vs 36.2 months, p < 0.001). All leads were evaluated for acute and chronic sensing and capture thresholds, and impedance. RESULTS: Acute and in particular chronic atrial and ventricular sensing and capture thresholds in SE EPI and TV leads were essentially equivalent. [table: see text]. The chronic impedance of TV leads (atrial 525 ohms, ventricular 520 ohms) was consistently higher than EPI leads (atrial 404 ohms, ventricular 386 ohms). CONCLUSION: At intermediate follow-up, SE EPI leads are functionally equivalent to SE TV leads. We recommend the use of SE EPI leads as long as practically feasible prior to using the TV approach in children who will require a life-time of pacing.     

Is use of temporary pacing wires following coronary bypass surgery really necessary?

AIM: Temporary epicardial pacing wires (TEPW) which are routinely used after coronary bypass grafting may result in significant complications. We sought to identify variables that predict TEPW implantation and thereby limit their use. METHODS: This prospective study enrolled 564 patients (296 underwent coronary artery bypass grafting with cardiopulmonary bypass [ONCAB] and 268 underwent off-pump coronary artery bypass grafting, OPCAB). TEPW were placed in patients with the intraoperative presence of one or more of the following criteria: sinus bradycardia, sinus arrest, nodal/junctional rhythms, atrioventricular block, bundle branch block, ventricular tachycardia, or onset of atrial fibrillation. RESULTS: Only 31 (5.5%) patients [ONCAB: 20 (6.8%) (ventricular: 14, bichamber: 6); OPCAB: 11 (4.1%) (ventricular: 9, bichamber: 2)] had temporary epicardial pacing wires implanted intraoperatively. Indications for using temporary epicardial pacing wires for ONCAB were sinus bradycardia (8), nodal/junctional rhythms (3), atrioventricular block (3), atrial fibrillation (4), and bundle branch block (2), and for OPCAB were sinus bradycardia (8), nodal/junctional rhythms (2), and atrioventricular block (1). Mean duration for pacing was 22.4 h for the ONCAB group and 11.3 h for the OPCAB group. There were no temporary epicardial pacing wires associated complications. One paced OPCAB patient required a permanent pacemaker and 2 non-paced OPCAB patients required transvenous pacing wires. Univariate and multivariate analyses were also conducted to determine risk factors for TEPW. CONCLUSION: TEPW implantation is overused in cardiac surgery and by identifying independent predictors for pacing we conclude that TEPW use should be limited to a select few.     

Epicardial pacemaker implantation and follow-up in patients with a single ventricle after the Fontan operation

OBJECTIVES: There is an increasing incidence of sinus node dysfunction after the Fontan procedure. Inability to maintain atrioventricular synchrony after the Fontan operation has been associated with an adverse late outcome. Although pacing may be helpful as a primary or adjunct modality after the Fontan procedure, the effects of performing a late thoracotomy or sternotomy for epicardial pacemaker implantation are unknown. In addition, little is known about the long-term effectiveness of epicardial leads in patients with single ventricles. The purpose of this study was to compare the hospital course and follow-up of epicardial pacing lead implantation in patients with Fontan physiology and patients with 2-ventricle physiology. METHODS: We retrospectively reviewed all isolated epicardial pacemaker implantations and outpatient evaluations performed between January 1983 and June 2000. RESULTS: There was no difference in the perioperative course for the 31 Fontan patients (27 atrial and 41 ventricular leads [68 total]) compared with the 56 non-Fontan subjects (9 atrial and 61 ventricular leads [70 total]). The median length of stay in Fontan and non-Fontan patients was 3 and 4 days, respectively. There was no early mortality in either group. Pleural drainage for 5 days or longer was reported in 4% of the Fontan cohort and 3% of the non-Fontan group. Late pleural effusions were identified in only 2 patients in the Fontan group and 2 patients in the non-Fontan group. There was no significant difference in epicardial lead survival between the Fontan group and the non-Fontan group (1 year, 96%; 2 years, 90%; 5 years, 70%). The overall incidence of lead failure was 17% (24/138). CONCLUSIONS: Epicardial leads can be safely placed in Fontan patients at no additional risk compared to patients with biventricular physiology. Sensing and pacing qualities were relatively constant in both the Fontan and non-Fontan groups over the first 2 years after implantation.     

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.     

Temporary A-V sequential pacing using transluminal pacing electrodes

A case is presented which describes the initiation of atrialventricular (A-V) sequential pacing using atrial epicardial wires and an in situ transluminal ventricular pacing probe. A 68year-old female with a permanent A-V sequential pacemaker was scheduled for elective aortocoronary bypass. Following sternotomy, pacing function was converted to ventricular pacing (WI) with the use of electrocautery. A Chandler® V-pacing probe was introduced through a Paceport® (American Edwards) pulmonary artery catheter and with a paced increase in ventricular rate, the cardiac output increased from 2.8 to 3.2 L · min^-1. At the conclusion of cardiopulmonary bypass the patient was in sinus rhythm at a rate of 67 · min^-1 and was paced to a faster rate using bipolar atrial epicardial wires. The patient subsequently developed intermittent heart block so temporary A-V sequential pacing was established using atrial epicardial wires and the in situ ventricular pacing probe. Pacing was achieved at routine generator output settings of seven milliamps (mA) for both atrium and ventricle and at an A-V interval of 0.120 sec. This resulted in an immediate increase in cardiac output from 3.3 to 4.1L- min^-1. The compatability of these two pacing systems offers an increased margin of safety in cardiac surgery patients requiring atrial pacing, who are at risk for developing postoperative heart block.     

Permanent Atrial Pacing: Improved Methods of Electrode Implantation and Current Therapeutic Uses

Permanent atrial pacing provides an important approach to refractory supraventricular and selected ventricular arrhythmias. This report reviews current techniques for instituting atrial pacing; namely, epicardial electrode implantation and transvenous coronary sinus placement. An improved method of atrial epicardial electrode implantation is described. Representative cases are reviewed to illustrate clinical settings in which permanent atrial pacing has controlled previously refractory arrhythmias.     

A simplified technique for implantation of left ventricular epicardial leads for biventricular resynchronisation using video-assisted thoracoscopy (VATS)

Objective: Cardiac resynchronisation therapy for treatment of heart failure requires transvenous insertion of both a right ventricular and left ventricular pacing lead. Implantation of the latter by way of the coronary sinus often fails. Therefore, alternative techniques for insertion are required. We applied a simple video-assisted surgical technique (VATS) using only two ports for the insertion of left-ventricular screw-in electrodes. Methods: Fifteen patients (M: 10; F: 5; mean age: 62.2 years; range: 46–76 years) with heart failure meeting the ACC/AHA guidelines for implantation of biventricular pacing underwent transvenous insertion of the right atrial sensor lead and the right ventricular pacing lead. In all of them transvenous implantation of the left ventricular pacing lead failed, and they were planned for VATS. In right-lateral decubitus position and under single-lung ventilation a camera port and a flexible instrumentation port were inserted in the forth intercostal space. By using routine instruments, a T-shaped incision was made lateral to the phrenic nerve and an electrode was screwed in. The lead was guided subcutaneously to the pacemaker. Results: Mean skin-to-skin operating time was 55 ± 16 min, no conversion to thoracotomy was necessary. All patients were extubated in the operating room and remained in the intensive care unit for less than 24 h. Chest tubes were removed after a mean of 1.6 ± 0.5 days and the patients were discharged after a mean of 4 ± 1.3 days. Intraoperative and postoperative pacing thresholds at 1 and 7 months were satisfactory in all cases and there was no lead dislocation. All but two patients had an improvement of their NYHA function class. There was neither surgical morbidity nor mortality. Conclusions: Video-assisted thoracoscopy over two ports seems to be an excellent alternative procedure for epicardial lead implantation. It is readily available and produces good pacing results at a short intervention time and tolerable stress for the patients.     

Clinical Experience with Permanent Atrioventricular Sequential Pacing

In a 23-month period, we implanted 26 permanent atrioventricular (AV) sequential pacing units in 11 women and 15 men ranging from 37 to 85 years old (mean, 68 years). Indications for pacing were complete heart block in 12 patients and sick sinus syndrome in 14 patients.Cardiac index, using standard thermodilution techniques, was determined in 9 patients during ventricular pacing and AV sequential pacing at constant heart rate. Atrioventricular sequential pacing was superior in all patients, with a mean increase in cardiac index of 22% (p < 0.01). Complications of AV sequential pacing included the need to revise two pulse generator pockets due to the large size of the pulse generator. One transvenous atrial lead displacement occurred in a patient who had previously undergone right atrial appendage ligation at open-heart operation. No failures of pacing or sensing occurred during 279 patient-paced months.The theoretical hemodynamic advantage of AV sequential pacing has been confirmed in this clinical trial. Experience with electrode placement and improvements in pulse generator design should aid in eliminating complications with this pacing modality.     

Midterm results of surgical treatment of systemic ventricular outflow obstruction in Fontan patients

BACKGROUND: Achieving unobstructed blood flow from the systemic ventricle to the aorta is important during the Fontan procedure for complex cyanotic congenital heart disease when there is systemic ventricular outflow obstruction (SVOO). Because SVOO can progress after the Fontan procedure if there is morphologic obstruction, we have adopted a policy of relieving obstructions to systemic blood flow. METHODS: Twenty-five patients were treated by the Fontan procedure with SVOO. Twenty-one patients had undergone prior pulmonary artery banding and 10 patients had undergone prior arch repair. Systemic ventricular outflow obstruction progressed in 5 patients after the Fontan procedure. Main diagnosis was single ventricle in 12, tricuspid atresia in 5, transposition of the great arteries in 4, double-outlet right ventricle in 3, and common atrioventricular canal in 1. Mean age at operation was 6.5 years (range 1 to 15 years) and the average preoperative pressure gradient across the ascending aorta and systemic ventricle was 29 mm Hg (range 0 to 100 mm Hg). The Damus-Kaye-Stansel procedure was performed in 18 patients (double-barrel anastomosis in 13, end to side anastomosis in 5), and subaortic resection or ventricular septal defect or bulboventricular foramen enlargement was performed in 7. Double-barrel anastomosis has been our first choice since 1994, if the pulmonary valve is intact. Follow-up has ranged from 4 months to 14 years (average 5.0 years). Twenty-three of the 25 patients have undergone recatheterization (average 21.4 months later). RESULTS: No early deaths were found; one late death was reported of a patient with single right ventricle (4.0%). The postoperative average pressure gradient was 1.1 mm Hg (0 to 10 mm Hg), and the average right atrial pressure was 14 mm Hg (9 to 20 mm Hg). In all patients who underwent ventricular septal defect or bulboventricular foramen enlargement, regular sinus rhythm was maintained postoperatively. Regarding the Damus-Kaye-Stansel procedure, there was minimal progression of semilunar valve insufficiency except in 1 patient who underwent end-to-side anastomosis with moderate pulmonary regurgitation postoperatively. CONCLUSIONS: The midterm results of the Fontan procedure with SVOO have been satisfactory. Because SVOO might progress after the Fontan procedure if there is morphologic obstruction, an appropriate strategy to relieve obstruction to systemic blood flow should therefore be performed concomitantly with the Fontan procedure.     

Temporary external DDD pacing after cardiac operations

Temporary atrial and ventricular pacing in the DVI, VVI, and AOO modes using atrioventricular sequential DVI devices is routinely used in cardiac operations. This study evaluated a new temporary external DDD pacemaker (Medtronic 5345 External Pulse Generator) capable of ten pacing modes. Thirty-nine devices have been applied to 38 adult patients (27 male, 11 female) after a variety of open heart procedures. Group 1 had atrial pacing wires placed 1.5 to 2.0 cm apart superiorly on the right atrium, group 2 had atrial wires placed 1.0 to 1.5 cm apart on the right atrial free wall, and group 3 had atrial wires placed on the right atrial free wall 0.8 cm apart, using a Silastic ring for fixation. Ventricular wires were placed on the free wall (group 1) or the diaphragmatic surface (groups 2 and 3) of the right ventricle. Postoperative atrial and ventricular sensing and pacing thresholds were obtained on return to the intensive care unit; analysis of variance demonstrated a significantly greater atrial sensing threshold in group 3. Four patients in group 1 permanently lost atrial sensing, 1 patient in group 2 intermittently lost atrial sensing at 24 hours with return at 36 hours postoperatively, and 1 patient in group 1 lost ventricular sensing capability. All other patients had adequate atrial and ventricular sensing capability documented until elective pacemaker removal (mean, 166 hours; range, 17 to 667.5 hours). Nineteen patients required some form of temporary pacing postoperatively; 11 patients demonstrated hemodynamic benefit from a pacing mode that is not available on the currently used DVI devices, and 7 of these required true DDD pacing capability. Six patients benefited from atrial pacing with adequate atrial sensing and simultaneous ventricular backup. Burst pacing with the device was used successfully to treat postoperative atrial flutter in 2 patients. We conclude that temporary external DDD pacing is feasible and effective in postoperative cardiac surgical patients. Atrial sensing is possible in most patients but electrode positioning is important for adequate thresholds. In some patients, hemodynamic as well as electrophysiologic improvement can be demonstrated with universal DDD pacing capability as compared with standard DVI pacing.     

Acute hemodynamic benefit of multisite ventricular pacing after congenital heart surgery

BACKGROUND: Cardiac dysfunction after congenital heart surgery is a major cause of morbidity and mortality. Cardiac resynchronization through multisite ventricular pacing (MSVP) improves cardiac index and ventricular function, and lowers systemic vascular resistance (SVR) in adults with heart failure and interventricular conduction delay. METHODS: The acute hemodynamic effects of MSVP after congenital heart surgery were assessed. Twenty-nine patients (aged 1 week to 17 years) with prolonged QRS interval had atrial and ventricular unipolar epicardial temporary pacing leads placed at surgery. Group 1 consisted of patients with a single ventricle (n = 14); group 2 included patients with two-ventricle anatomy (tetralogy of Fallot, ventricular septal defect) undergoing ventricular surgery (n = 10); and group 3 included patients with two-ventricle anatomy undergoing other cardiac surgery (n = 5). At a mean postoperative day 1 (range, 0 to 6), blood pressure, systemic and mixed venous oxygen saturations, electrocardiograms, and echocardiograms were obtained before and after 20 minutes of MSVP. RESULTS: The QRS duration decreased with MSVP in all patients (mean, 23%, p < 0.005). Systolic blood pressure improved in all patients (mean, 9.7%, p < 0.005). Cardiac index improved in 19 of 21 patients tested, with no change in 2 patients (mean, 15.1%, p = 0.0001). In 2 patients, MSVP facilitated weaning from cardiopulmonary bypass. Echocardiographic mitral or tricuspid valve inflow was not significantly different with MSVP. CONCLUSIONS: Multisite ventricular pacing results in improved cardiac index and increased systolic blood pressure, and it can also facilitate weaning from cardiopulmonary bypass. Multisite ventricular pacing may be used as adjunct to standard postoperative treatment of cardiac dysfunction after congenital heart surgery.     

Pancreatitis in Fontan patients is related to impaired ventricular relaxation

BACKGROUND: Pancreatitis following cardiopulmonary bypass is a well-known complication in adults undergoing cardiac surgery. However, the occurrence of pancreatitis in pediatric patients undergoing repair of congenital heart disease is under-appreciated. Post-Fontan patients are particularly prone to postoperative pancreatitis. In an effort to identify specific perioperative factors predictive of postoperative pancreatitis, we retrospectively reviewed a group of Fontan patients. METHODS: From June 1996 to June 2001, 40 patients underwent a modified Fontan operation. Four patients developed acute pancreatitis postoperatively. The preoperative, intraoperative, and postoperative hemodynamics and ventricular function parameters were retrospectively analyzed and compared to 10 randomly selected Fontan patients who did not have pancreatitis. Preoperative echocardiographic and angiographic data, including digitized ventricular pressure tracings, were reviewed to obtain ventricular relaxation time constant (tau), pulmonary vascular resistance (PVR), ventricular end diastolic pressure (VEDP), positive dp/dt and negative dp/dt values. RESULTS: Patients developing acute pancreatitis had very high mortality (50%) compared to no mortality in the control group. The mean preoperative tau was significantly prolonged (41 ms vs 26 ms in control group, p < 0.001), and pre operative systemic output (Qs) lower in the pancreatitis group (mean 2.75 L/min/m2) compared with controls (Qs of 5.09 L/min/m2, p < 0.03). CONCLUSIONS: Impaired ventricular relaxation and decreased preoperative cardiac output are predictive of increased risk of postoperative pancreatitis in Fontan patients. Evaluation of preoperative diastolic function in these patients may provide additional insights in to clinical outcome following the Fontan procedure.     

Cardiac pacing in premature infants and neonates: steroid eluting leads and automatic output adaptation.

BACKGROUND: Appropriate generator and lead selection as well as techniques of implantation are most important aspects of cardiac pacing in the extremely young patient. Here we report the clinical results using a new technique with automatic output adaptation based on evoked response in combination with steroid-eluting epicardial leads in small children. METHODS: One neonate and 2 premature infants underwent permanent pacemaker implantation because of congenital high-degree atrioventricular block or postoperative complete heart block, respectively. Steroid-eluting epicardial leads and a multiprogrammable pacemaker with automatic output adaptation were used. RESULTS: Intermuscular abdominal generator placement and epicardial suture-fixation of the bipolar lead through a subcostal approach was without complications. Serial follow-up examinations revealed safe and consistent pacemaker function up to 12 months after operation. CONCLUSIONS: The technique represents an excellent alternative for permanent cardiac pacing in extremely small patients. We believe that it provides an increase in functional lifetime of the devices and delays the need for battery replacement with its associated complications in this young patient population.     

Comparison of longevity, pacing, and sensing characteristics of steroid-eluting epicardial versus conventional endocardial pacing leads in children

OBJECTIVE: Because of either cardiac anatomy or small size, pacing in children often occurs by means of epicardial leads. The disadvantage of epicardial leads is the shorter longevity of these leads compared with endocardial leads. During short-term follow-up, improved stimulation thresholds were found for the newer steroid-eluting epicardial leads. The longevity of these leads may be better than that of conventional epicardial leads. An improved longevity of epicardial leads may influence the choice to either epicardial or endocardial pacing in children. METHODS: We studied the longevity and the pacing and sensing characteristics of 33 steroid-eluting epicardial pacing leads (group I, 15 atrial, 18 ventricular) implanted between November 1991 and October 1996 in 20 children with a mean age of 7.6 +/- 6.5 years (mean +/- SD), and 29 endocardial pacing leads (group II, 15 atrial, 14 ventricular) implanted during the same period in 21 children with a mean age of 11.7 +/- 4.7 years. RESULTS: The mean follow-up in group I was 2.9 +/- 1.6 years and in group II 3.1 +/- 1.7 years (P =.61). The 2-year survival of the leads in group I was 91% +/- 5% and in group II 86% +/- 7% (P =.97). Lead failure occurred in both groups in 4 leads (P =.85). Chronic stimulation and sensing thresholds were similar. CONCLUSIONS: Steroid-eluting epicardial leads have the same longevity as the conventional endocardial leads. Pacing and sensing thresholds were similar and did not change during follow-up. Therefore steroid-eluting epicardial pacing leads are a good alternative for endocardial leads in small children and in children with congenital heart disease.     

Abnormalities in von Willebrand factor and antithrombin III after cardiopulmonary bypass operations for congenital heart disease.

In patients with congenital heart disease two poorly understood postoperative complications are pulmonary hypertensive crises after repair of large atrioventricular or ventricular septal defects and right atrial and pulmonary thrombi after the Fontan operation. In this study we assessed whether cardiopulmonary bypass in these patients is associated with the release of agents that might induce platelet aggregation and vasoconstriction, such as biologically active von Willebrand factor and platelet-activating factor. In addition, we measured levels of anticoagulants such as antithrombin III and proteins C and S. Three groups of patients with congenital heart disease undergoing cardiopulmonary bypass were monitored through the perioperative period for secundum atrial septal defects, large atrioventricular or ventricular septal defects, and tricuspid atresia or univentricular heart (Fontan candidates). Control values were obtained from age-matched patients; patients requiring major noncardiac operations and those with cardiac disease not requiring cardiopulmonary bypass were also studied. After cardiopulmonary bypass in all three groups biologic activity of von Willebrand factor increased markedly in the immediate and early postoperative periods compared with preoperative values, whereas antithrombin III values were decreased. Platelet-activating factor was detected in only two patients with congenital heart disease, both in the early postoperative period. In contrast, patients who did not have cardiopulmonary bypass did not show these abnormalities. All measured parameters normalized at late follow-up (6 to 18 months after operation). Although cardiopulmonary bypass in these patients resulted in increased von Willebrand factor activity and decreased antithrombin III, changes that may predispose the patient to platelet aggregation and thrombus formation, absolute values in individual patients alone were not predictive of pulmonary hypertensive crises or detectable thrombi. This suggests that these hematologic abnormalities may contribute to but are not by themselves a cause of morbidity in the early postoperative period. Moreover, the increased von Willebrand factor biologic activity seen postoperatively in patients with congenital heart disease suggests that use of synthetic vasopressin may be ineffective and potentially detrimental.     

Biventricular pacing in a patient with severe congestive heart failure

We report a case of dilated cardiomyopathy with severe congestive heart failure (ejection fraction: 19%) and complete left bundle branch block (QRS duration: 240 ms) 13 years after aortic valve replacement. Permanent biventricular pacing was implanted by inserting a left ventricular lead thorough a small left thoracotomy following intravenous insertion of right atrial and ventricular endocardial leads. Biventricular pacing increased hemodynamic parameters such as blood pressure, cardiac output and decreased mitral regurgitation. Symptoms and exercise tolerance improved dramatically. Left ventricular epicardial lead insertion via a small thoracotomy is thus useful in selected patients.     

Tempor?re Schrittmachertherapie bei herzchirurgischen Operationen

Bradycardia during and after cardiac surgery requiring temporary pacing is observed in roughly 50% of patients. Complete heart block as well as bradycardia associated with a sinus node dysfunction or permanent atrial fibrillation are the most common types of perioperative bradycardia; however, in some cases even a heart rate below 80 beats/min can be associated with hemodynamic problems. Finally, the occurrence of bradycardia in the immediate postoperative period after cardiac surgery cannot be predicted with reasonable accuracy. Thus, implantation of temporary epimyocardial stimulation leads in every patient undergoing cardiac surgery is common practice. The versatility of temporary pacing in cardiac surgery is unique, as all parts of the heart can be accessed during the operation. Thereby it allows temporary atrial, AV-sequential, P-wave synchronized or biventricular pacing in addition to ventricular pacing, the only pacing mode available for temporary pacing outside cardiac surgery. This results in desirable and substantial hemodynamic advantages compared to single chamber ventricular pacing for cardiac surgery patients in the perioperative period. This article summarizes the key elements of temporary pacing after cardiac surgery and adds some practical points.