Mechanical support for bridge to transplant in an infant with post-cardiotomy end-stage heart failure and complete heart block: report of a case.

The patient was diagnosed with perimembranous ventricular septal defect (VSD). She underwent VSD closure and muscle bundle resection across right ventricular outflow tract at the age of 3 months. Since then, she had suffered from severe heart failure and complete heart block. Permanent pacemaker generator was implanted in the left hypochondrium. She was depended on continuous catecholamine administration, so transferred to our hospital for further management. On arrival, her body weight was 5686 g (- 2.7 SD). She underwent Excor pediatric left ventricular assist device implantation at the age of 9 months. Because the position of the left ventricular assist device cannula interfered with the pacemaker, herein, the pacemaker pocket was newly created in the left thoracic cavity. An 1 mm in thickness of expanded polytetrafluoroethylene sheet was trimmed and sutured under the anterolateral wall of left thoracic cavity as a pacemaker pocket. Bipolar ventricular lead was sutured on left ventricular apex and basal wall to face each other, mimicking cardiac regeneration therapy. Even though she unfortunately required right diaphragmatic plication for iatrogenic phrenic nerve palsy, her respiratory function was well maintained; therefore, secondary right heart failure was not observed. Her cardiopulmonary function was quite stable until post-operative day 275 when the patient was transferred to another hospital for heart transplantation.

Temporary pacemaker implantation through umbilical vein in a low birth weight neonate with congenital complete heart block.

Congenital heart block is a rare and lethal condition in paediatric population associated with maternal connective tissue disorders and rarely with structural cardiac disease like atrioventricular canal defects with or without left isomerism and congenitally corrected transposition of great arteries. Pacing in neonate if indicated is generally accomplished by epicardial pacing systems. However, in cases of significant bradycardia and haemodynamic instability, temporary pacemaker implantation via transvenous approach remains as a suitable option. Despite the advances in percutaneous catheter interventions, use of transvenous pacing in newborn is extremely challenging due to inadvertent risk of vessel injury, thrombus formation and mortality, and most of the time technical inability to place the lead within the right ventricular cavity. We report a case of congenital complete atrioventricular block in a premature male with birth weight of 1.51 kg who was managed with temporary pacemaker implantation through umbilical vein.

Pacemaker Implantation in Neonates and Infants: Favorable Outcomes with Epicardial Pacing Systems.

The implantation of pacemakers (PM) in neonates and infants requires particular consideration of small body size, marked body growth potential, and the decades of future pacing therapy to be expected. The aim of this study is to quantify the complications of implantation and outcome occurring at our center and to compare these with other centers. Retrospective analysis of 52 consecutive patients undergoing PM implantation at a single tertiary care center within the first year of life. PMs were implanted at a median age of 3 months (range 0-10 months). Structural heart defects were present in 44 of 52 patients. During a median follow-up time of 40.4 months (range 0.1-114 months), measurements for sensing, pacing thresholds, and lead impedance remained stable. No adverse pacing effect was observed in left ventricular function or dimensions over time. There were 20 reoperations in 13 patients at a median time of 4.7 years (range 0.05-8.2 years) after implantation, for end of battery life (n = 10), lead dysfunction (n = 3), device dislocation (n = 3), infection (n = 3), and diaphragmatic paresis (n = 1). No PM-related mortality occurred. Epicardial pacemaker implantation in neonates and infants is an invasive but safe and effective procedure with a relatively low risk of complications. Our current implantation technique and the use of bipolar steroid-eluting electrodes, which we prefer to implant on the left ventricular apex, lead to favorable long-term results.

Hypoplastic Left Heart Syndrome with Congenital Complete Heart Block.

Congenital complete atrioventricular block (CCAVB) is a rare condition with an incidence of 1 of 20,000 live births. Hypoplastic left heart syndrome (HLHS) occurs more frequently than CCAVB and occurs in 1 of 5000 live births. HLHS in association with CCAVB is exceedingly rare. In this report, we describe a rare case of HLHS and CCAVB diagnosed in utero. Postnatal diagnosis, management and outcome are presented as well as review of the medical literature.

Bidirectional ventricular tachycardia?

A 65-year-old woman was admitted to the hospital because of a syncopal episode with documented transient complete atrioventricular block. A DDD pacemaker was implanted. Post implantation, the patient was diagnosed with bidirectional ventricular tachycardia. Analysis of the arrhythmia and differential diagnosis is performed.

Peri-operative management of hysterostomy in a parturient with complete heart block, placenta accreta and intrauterine death.

BACKGROUND: Complete heart block in pregnancy has serious implications particularly during the period of delivery. This is more so if the delivery is an operative one as the presence of heart block may produce haemodynamic instability in the intra operative period. We report a unique case of a pregnant mother with complete heart block undergoing hysterostomy, complicated by placenta accreta and intrauterine death. CASE PRESENTATION: A 37 year old Malaysian Chinese parturient was admitted at 25 weeks gestation following a scan which suggested intrauterine death and placenta accreta. She was diagnosed to have congenital complete heart block after her first delivery eight years previously but a pacemaker was never inserted. These medical conditions make her extremely likely to experience massive bleeding and haemodynamic instability. Among the measures taken to optimise her pre-operatively were the insertion of a temporary intravenous pacemaker and embolization of the uterine arteries to minimize peri-operative blood loss. She successfully underwent surgery under general anesthesia, which was relatively uneventful and was discharged well on the fourth post-operative day. CONCLUSION: Congenital heart block in pregnancies in the presence of potential massive bleeding is best managed by a team, with meticulous pre-operative optimization. Suggested strategies would include insertion of a temporary pacemaker and embolization of the uterine arteries to reduce the risk of the patient getting into life threatening situations.

A rare cause of pacemaker failure: interatrial block.

Pacemaker and implantable cardioverter defibrillators (ICD) systems are useful in detection and differentiation of many symptomatic and asymptomatic arrhythmias. In this report, we described a rare condition that caused by failure in detection of a clinical tachyarrhythmia by a dual chamber pacemaker that implanted because of intermittent atrioventricular (AV) block and sinus node disease in a 46-year-old patient. In our case, bidirectional interatrial block was demonstrated; and the symptoms associated with high ventricular rate caused by left atrial tachyarrhythmias relieved after AV node ablation.

Pattern of recovery for transient complete heart block after open heart surgery for congenital heart disease: duration alone predicts risk of late complete heart block.

Transient complete heart block (TCHB) is defined as complete interruption of atrioventricular conduction (AVC) after cardiac surgery followed by return of conduction. This study aimed to assess the risk for the development of late complete heart block (LCHB) after recovery of TCHB and to examine the electrocardiographic and electrophysiologic properties of the AVC system after TCHB. Of the 44 patients in this study who experienced TCHB, 37 recovered completely. Seven patients progressed from TCHB to intermittent CHB or LCHB requiring pacemaker implantation. Preoperative, early postoperative, and late postoperative electrocardiograms as well as postoperative atrial stimulation were obtained. The results showed that the median duration of TCHB was 5 days in the TCHB group compared with 9 days in the LCHB group (p = 0.01). All 37 subjects with TCHB recovered AVC within 12 days, but only two with LCHB did so (p = 0.02). The risk of LCHB for the patients with 7 days of postoperative TCHB or longer was 13 times greater than for the patients with fewer than 7 days of TCHB (p = 0.01). The median late postoperative PR interval was slightly but significantly longer in the LCHB group than in the TCHB group (p = 0.02). In contrast, the electrophysiologic properties between the two groups did not differ significantly. From those findings, we concluded that delayed recovery of AVC after surgical TCHB (≥7 days), but not electrophysiologic properties of recovered AVC assessed early in the postoperative period strongly, predicts risk of LCHB. Follow-up evaluation of AVC is particularly indicated for the delayed recovery group.

Azygos approach for pacemaker placement in an infant.

A pacemaker insertion through the azygos vein in a child is presented. When both the low weight of the child and mediastinitis precluded standard approaches, the azygos approach proved to be an alternative and a straightforward bailout solution.

Postoperative heart block in children with common forms of congenital heart disease: results from the KID Database.

INTRODUCTION: Cardiac conduction system injury is a cause of postoperative cardiac morbidity following repair of congenital heart disease (CHD). The national occurrence of postoperative complete heart block (CHB) following surgical repair of CHD is unknown. We sought to describe the occurrence of and costs related to postoperative CHB following surgical repair of common forms of CHD using a large national database. METHODS AND RESULTS: Retrospective, observational analysis performed over a 10-year period (2000-2009) using the Kids' Inpatient Database (KID). Visits for patients ≤24 months of age were identified who underwent surgical repair of ventricular septal defects (VSD), atrioventricular canal defects (AVC), and tetralogy of Fallot (TOF). Patients were identified who were diagnosed with postoperative CHB, further identifying those requiring a new pacemaker placement during the same hospitalization. Costs associated with visits were calculated. There were 16,105 surgical visits: 7,146 VSD, 3,480 AVC, and 5,480 TOF. There was a decrease in postoperative mortality (P = 0.0001) with no significant change in postoperative CHB. Hospital stay and cost were higher with CHB and placement of a permanent pacemaker. Repair of AVC (OR 1.77; [1.32-2.38]) was associated with a higher rate of postoperative CHB. Length of hospital stay and total cost were significantly increased with the development of postoperative CHB and increased further with placement of a permanent pacemaker. CONCLUSION: There has been little change over time in the frequency of postoperative CHB in patients undergoing repair of VSD, AVC, and TOF. Postoperative CHB results in major added cost to the healthcare system.

Congenital complete heart block: single tertiary centre experience.

BACKGROUND: Congenital complete heart block (CCHB) is an uncommon although important and potentially serious condition contributing to neonatal morbidity and mortality. AIMS: To study the characteristics and outcomes of infants born with CCHB at a single tertiary centre. METHODS: A retrospective review of all infants with CCHB over the last 20 years was carried out to determine the outcomes, and the indications and timing of pacemaker insertion. RESULTS: Fifteen live born infants (10 male, 5 female) with CCHB were identified. Their mean (and SD) gestation and birth weight were 37 (3.3) weeks and 3100 (448) grams respectively. Maternal systemic lupus erythematosus (SLE) antibodies were present in eight (53%) pregnancies and two infants had congenitally corrected transposition of the great arteries (cCTGA). The median heart rate/minute at birth was 60 (range 40-80). Thirteen (87%) patients to date required a pacemaker. The median age of insertion of a pacemaker device was six months (range 2 days-16 years). All patients were paced epicardially - six initially with a single chamber and five with a dual chamber pacemaker. At the time of generator change, dual chamber pacemakers were used. The median life of an implanted pacemaker was six years (3-10 years). Except for a patient with cCTGA who has undergone a double switch procedure, all the patients had good systemic ventricular function. There was one death in the group unrelated to CCHB. CONCLUSIONS: CCHB is a uncommon but potentially serious condition in infancy. While a significant number of infants need a pacemaker, the overall outcome of infants with CCHB in our experience is good.

Local Impedance Drop Predicts Durable Conduction Block in Patients With Paroxysmal Atrial Fibrillation.

OBJECTIVES: This analysis was performed to evaluate the transition of local impedance (LI) drop during pulmonary vein isolation (PVI) to durable block and mature lesion formation based on 3-month mapping procedures. BACKGROUND: A radiofrequency catheter measuring LI has been shown to be effective for performing PVI in patients with paroxysmal atrial fibrillation. Previous analysis has demonstrated LI drop to be predictive of pulmonary vein segment conduction block during an atrial fibrillation ablation procedure. METHODS: Fifty-eight patients who had undergone LI-blinded de novo PVI returned for a 3-month mapping procedure. PVI ablation circles were divided into 16 anatomic segments for classification (durable block or gap), and the median LI drop within segments with an interlesion distance of ≤6 mm was compared. A total of 51 data sets met the criteria for segmental analysis of LI performance. RESULTS: At the 3-month procedure, PV connection was confirmed in at least 1 PV segment in 35 of the included patients. LI drop outperformed generator impedance drop as a predictor of durable conduction block (area under the receiver-operating characteristic curve: 0.79 vs 0.68; P = 0.003). Optimal LI drops were identified by left atrial region (anterior/superior: 16.9 Ω [sensitivity: 69.1%; specificity: 85.0%; positive predictive value for durable conduction block: 97.7%]; posterior/inferior:14.2 Ω [sensitivity: 73.8%; specificity: 78.3%; positive predictive value: 96.9%]). Starting LI before radiofrequency (RF) application was significantly different among healthy, gap, and mature scar tissue and was also a contributing factor to achieving an optimal LI drop (85.2% of RF applications with a starting LI of ≥110 Ω achieved the optimal regional drop or greater). CONCLUSIONS: LI drop is predictive of durable PV segment isolation. Preablation starting LI is associated with the magnitude of LI drop. These findings suggest that a regional approach to RF ablation guided by LI combined with careful interlesion distance control may be beneficial in patients with paroxysmal atrial fibrillation (Electrical Coupling Information From the Rhythmia HDx System and DirectSense Technology in Subjects With Paroxysmal Atrial Fibrillation [LOCALIZE]; NCT03232645).

AV nodal dual pathway electrophysiology and Wenckebach periodicity.

INTRODUCTION: The precise mechanism(s) governing the phenomenon of AV nodal Wenckebach periodicity is not fully elucidated. Currently 2 hypotheses, the decremental conduction and the Rosenbluethian step-delay, are most frequently used. We have provided new evidence that, in addition, dual pathway (DPW) electrophysiology is directly involved in the manifestation of AV nodal Wenckebach phenomenon. METHODS AND RESULTS: AV nodal cellular action potentials (APs) were recorded from 6 rabbit AV node preparations during standard A1A2 and incremental pacing protocols. His electrogram alternans, a validated index of DPW electrophysiology, was used to monitor fast (FP) and slow (SP) pathway conduction. The data were collected in intact AV nodes, as well as after SP ablation. In all studied hearts the Wenckebach cycle started with FP propagation, followed by transition to SP until its ultimate block. During this process complex cellular APs were observed, with decremental foot formations reflecting the fading FP and second depolarizations produced by the SP. In addition, the AV node cells exhibited a progressive loss in maximal diastolic membrane potential (MDP) due to incomplete repolarization. The pause created with the blocked Wenckebach beat was associated with restoration of MDP and reinitiation of the conduction cycle via the FP wavefront. CONCLUSION: DPW electrophysiology is dynamically involved in the development of AV nodal Wenckebach periodicity. In the intact AV node, the cycle starts with FP that is progressively weakened and then replaced by SP propagation, until block occurs. AV nodal SP modification did not eliminate Wenckebach periodicity but strongly affected its paradigm.