A surgical resection case of myxoma arising from the posterior wall of the left atrium complicated with complete atrioventricular block

An 80-year-old female was referred to our institution due to transient right upper limb weakness. Transthoracic and transesophageal echocardiography revealed a tumor in the left atrium. The tumor was attached to the posterior wall of the left atrium near the atrioventricular node. Intraoperative pathological examination revealed that the tumor was a myxoma, and complete resection was successfully performed. However, she experienced persistent complete atrioventricular block postoperatively and required pacemaker implantation.

A novel method for septal reduction therapy by three-dimensional guided transvenous intraseptal pulsed-field ablation

BACKGROUND

Pulsed-field ablation (PFA) is a nonthermal method for achieving selective cell death with little inflammation response. However, there are no reports of PFA for septal reduction therapy (SRT).

OBJECTIVE

The purpose of this study was to investigate the effectiveness and safety of PFA for SRT.

METHODS

A novel transvenous intraseptal PFA method with 3-dimensional (3D) guidance was introduced in Yorkshire pigs. Electrocardiographic parameters, transthoracic echocardiography, and histopathology were used to evaluated.

RESULTS

The maximum injury diameter of intramyocardial PFA increased with electric field intensity. After PFA, bipolar electrogram amplitude and pacing threshold measured by the PFA electrodes significantly decreased (F = 6.945, P = .007) or increased (F = 5.842, P = .024), respectively. In the ablated septal region, motion amplitude and systolic wall thickening rate significantly decreased and remained at low levels (motion amplitude: F = 20.793, P = .000; systolic wall thickening rate: F = 14.343, P = .000); however, septal thickness did not significantly change after PFA (F = 1.503, P = .248). Histologic examination showed specific cardiomyocyte death with gradually increased hyperchromatic cytoplasm and nuclear pyknosis, without obvious inflammatory cell infiltration in acute phase. TUNEL stain for fragmented DNA showed extensively positive in the ablation region 24 hours after PFA. During PFA, no sustained ventricular arrhythmia or atrioventricular conduction block occurred.

CONCLUSION

A novel intraseptal PFA method with 3D guidance was described. Intraseptal PFA resulted in effective myocardial injury and local hypokinesis without significant acute edema. Histologic examination showed widely programmed cardiomyocyte death with little inflammatory cell infiltration.

Atrioventricular conduction recovery immediately after the re-operation in a repaired CHD patient

This is a case of a 2.7-year-old girl with trisomy 21 and double outlet right ventricle who underwent epicardial pacemaker system placement for a surgical atrioventricular block and achieved atrioventricular conduction recovery immediately after residual ventricular septal defect closure. Although ventricular pacing ratio was 100% before re-operation, it declined to approximately 25% on the 6th post-operative day and was <1% 3 years after re-operation.

Junctional rhythm during cryoablation for typical atrioventricular nodal reentrant tachycardia

INTRODUCTION

Cryoablation is being used as an alternative to radiofrequency (RF) ablation for atrioventricular nodal reentrant tachycardia (AVNRT) owing to the lower risk of atrioventricular block (AVB) compared to RF ablation. Junctional rhythm often occurs during successful application of RF ablation for AVNRT. In contrast, junctional rhythm has rarely been reported to occur during cryoablation. This retrospective study evaluated the characteristics of junctional rhythm during cryoablation for typical AVNRT.

METHODS AND RESULTS

This retrospective study included 127 patients in whom successful cryoablation of typical AVNRT was performed. Patients diagnosed with atypical AVNRT were excluded. Junctional rhythm appeared during cryofreezing in 22 patients (17.3%). These junctional rhythms appeared due to cryofreezing at the successful site in the early phase within 15 s of commencement of cooling. Transient complete AVB was observed in 10 of 127 patients (7.9%), and it was noted that atrioventricular conduction improved immediately after cooling was stopped in these 10 patients. No junctional rhythm was observed before the appearance of AVB. No recurrence of tachycardia was confirmed in patients in whom junctional rhythm occurred by cryofreezing at the successful site.

CONCLUSION

Occurrence of junctional rhythms during cryoablation is not so rare and can be considered a criterion for successful cryofreezing. Furthermore, junctional rhythm may be associated with low risk of recurrent tachycardia.

Factors associated with temporary pacing insertion in patients with inferior ST-segment elevation myocardial infarction

Background

High-degree atrioventricular block (HAVB) is a prognostic factor for survival in patients with inferior ST-segment elevation myocardial infarction (STEMI). However, there is little information about factors associated with temporary pacing (TP). The aim of this study was to find factors associated with TP in patients with inferior STEMI.

Methods

We included 232 inferior STEMI patients, and divided those into the TP group (n = 46) and the non-TP group (n = 186). Factors associated with TP were retrospectively investigated using multivariate logistic regression model.

Results

The incidence of right ventricular (RV) infarction was significantly higher in the TP group (19.6%) than in the non-TP group (7.5%) (p = 0.024), but the incidence of in-hospital death was similar between the 2 groups (4.3% vs. 4.8%, p = 1.000). Long-term major adverse cardiovascular events (MACE), which were defined as a composite of all-cause death, non-fatal myocardial infarction (MI), target vessel revascularization (TVR) and readmission for heart failure, were not different between the 2 groups (p = 0.100). In the multivariate logistic regression analysis, statin at admission [odds ratio (OR) 0.230, 95% confidence interval (CI) 0.062–0.860, p = 0.029], HAVB at admission (OR 9.950, 95% CI 4.099–24.152, p<0.001), and TIMI-thrombus grade ≥3 (OR 10.762, 95% CI 1.385–83.635, p = 0.023) were significantly associated with TP.

Conclusion

Statin at admission, HAVB at admission, and TIMI-thrombus grade ≥3 were associated with TP in patients with inferior STEMI. Although the patients with TP had the higher incidence of RV infarction, the incidence of in-hospital death and long-term MACE was not different between patients with TP and those without.

Long-term outcomes of arrhythmia and distinct electrophysiological features in congenitally corrected transposition of the great arteries in an Asian cohort

Congenitally corrected transposition of the great arteries (ccTGA) is associated with various types of arrhythmia, including supraventricular tachycardia (SVT) and complete atrioventricular block (cAVB). Our study aims to characterize the arrhythmia burden, associated risk factors, arrhythmia mechanisms, and the long-term follow-up results in patients with ccTGA in a large Asian cohort.

METHODS

We enrolled 104 patients (43 women and 61 men) diagnosed with ccTGA at our institution. The mean age at last follow-up was 20.8 years.

RESULTS

For 40 patients (38%) with tachyarrhythmia, paroxysmal SVT (PSVT) and atrial arrhythmia were observed in 17 (16%) and 27 (26%) patients, respectively, with 4 patients (4%) having both types of SVT. The 20-year and 30-year SVT-free survival rates were 68% and 54%, respectively. Seven patients (7%) developed cAVB: 2 (2%) developed spontaneously, and the other 5 (5%) was surgically complicated (surgical risk of cAVB: 7%, all associated with ventricular septal defect repair surgery). PSVT was mostly associated with accessory pathways (5/9) but also related to twin atrioventricular nodal reentry tachycardia (3/9) and atrioventricular nodal reentry tachycardia (1/9). Most of the accessory pathways were located at tricuspid valve (9/10). Catheter ablation successfully eliminated all PSVT substrates (10/10) and most of the atrial arrhythmia substrates (3/5), with low recurrence rate.

CONCLUSIONS

The arrhythmia burden in patients with ccTGA is high and increases over time. However, cAVB incidence was relatively low and kept stationary in this Asian cohort. The mechanisms of SVT are complicated and can be controlled through catheter ablation.

Economic value and cost-effectiveness of biventricular versus right ventricular pacing: results from the BLOCK-HF study

Aims: The Biventricular vs Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK-HF) demonstrated that biventricular (BiV) pacing resulted in better clinical and structural outcomes compared to right ventricular (RV) pacing in patients with atrioventricular (AV) block and reduced left ventricular ejection fraction (LVEF; ≤50%). This study investigated the cost-effectiveness of BiV vs RV pacing in the patient population enrolled in the BLOCK-HF trial. Methods: All-cause mortality, New York Heart Association (NYHA) Class distribution over time, and NYHA-specific heart failure (HF)-related healthcare utilization rates were predicted using statistical models based on BLOCK-HF patient data. A proportion-in-state model calculated cost-effectiveness from the Medicare payer perspective. Results: The predicted patient survival was 6.78 years with RV and 7.52 years with BiV pacing, a 10.9% increase over lifetime. BiV pacing resulted in 0.41 more quality-adjusted life years (QALYs) compared to RV pacing, at an additional cost of $12,537. The "base-case" incremental cost-effectiveness ratio (ICER) was $30,860/QALY gained. Within the clinical sub-groups, the highest observed ICER was $43,687 (NYHA Class I). Patients receiving combined BiV pacing and defibrillation (BiV-D) devices were projected to benefit more (0.84 years gained) than BiV pacemaker (BiV-P) recipients (0.49 years gained), compared to dual-chamber pacemakers. Conclusions: BiV pacing in AV block patients improves survival and attenuates HF progression compared to RV pacing. ICERs were consistently below the US acceptability threshold ($50,000/QALY). From a US Medicare perspective, the additional up-front cost associated with offering BiV pacing to the BLOCK-HF patient population appears justified.

Cardiac Magnetic Resonance Identified the Fibrotic Lesion Associated with Syncope Attack Due to Complete Atrioventricular Block in a Patient with Hypertrophic Cardiomyopathy and Aortic Stenosis

An 84-year-old man presented with syncope. Prior to admission, ambulatory electrocardiogram had demonstrated non-sustained ventricular tachycardia. Echocardiography showed severe aortic stenosis. He was also diagnosed with hypertrophic cardiomyopathy (HCM) by cardiac magnetic resonance (CMR) showing remarkable inhomogeneous left ventricular hypertrophy and extensive late gadolinium enhancement (LGE) in the lesions at the upper border and right-ventricular side of the basal-mid septal wall. Finally, he showed complete atrioventricular (AV) block followed by a long pause and syncope several times after admission. In this case with several possible causes of syncope, the CMR findings suggested a clue concerning the etiology of his syncope: complete AV block in HCM.

Clinical Impact of Intraventricular Conduction Abnormalities After Transcatheter Aortic Valve Implantation With Balloon-Expandable Valves

Transcatheter aortic valve implantation (TAVI) often causes intraventricular conduction abnormalities (ICA), particularly left bundle branch block (LBBB) and advanced atrioventricular block, requiring pacemaker implantation (PMI). However, the relation between ICA and clinical outcomes after TAVI with balloon-expandable valves remains unclear, particularly in the Asian population. This retrospective study included all patients who underwent TAVI with balloon-expandable valves from October 2013 to September 2016. We defined ICA as new onset of complete LBBB (CLBBB) or PMI within 2 weeks after TAVI. We divided the patients into 2 groups: those with and without ICA (new-ICA and no-ICA groups) and we assessed 1-year outcome. Two hundred one consecutive patients underwent TAVI using balloon-expandable valves (mean age, 84.8 ± 5.7 years; women, 64%). ICA occurred in 47 patients (23%), 37 patients (18%) developed CLBBB, and 34 patients recovered from CLBBB within 1 year after TAVI. Ten patients (5%) who developed symptomatic bradycardia required PMI within 2 weeks after TAVI. At 30 days after PMI, 7 patients already had a very low ventricular pacing rate, and 6 patients who recovered from bradycardia needed pacing at 1 year. Patients with ICA tended to have high 1-year all-cause mortality, but there was no significant difference between the 2 groups (12% vs 7%, p = 0.15). In conclusion, ICA occurred in 23% of patients after TAVI with balloon-expandable valves, and approximately 90% of them recovered from ICA during the follow-up. There was no significant difference in 1-year all-cause mortality between the new-ICA and no-ICA groups.

Surgical Outcomes of Permanent Epicardial Pacing in Neonates and Young Infants Less Than 1 Year of Age

BACKGROUND

Open surgical implantation of epicardial leads in neonates and infants remains the first option of treatment. We reviewed the long-term outcomes after epicardial pacemaker implantation in neonates and infants.

METHODS

From 1989 to 2016, 48 patients (16 neonates) underwent pacemaker implantation within the first year of life. Their median age and weight were 66.5days (range: 0∼319 days), and 4.2kg (range: 1.9∼9.3kg), respectively, at the time of first pacemaker implantation. The indications for pacemaker implantation were postoperative or congenital atrioventricular block, sinus node dysfunction, and/or myocarditis-induced atrioventricular block. Forty-six (46) unipolar epicardial leads (non-steroid-eluting: 22; steroid-eluting: 24) and two bipolar leads (steroid-eluting) were inserted using a median sternotomy or subxiphoid approach.

RESULTS

The mean follow-up duration was 8.5±7.9years. The most commonly used generator mode at first implantation was VVI (n=24, 50.0%). Eleven (11) generator mode changes from the initial VVI or VVIR to dual-chamber pacing were made at a mean of 7.0±6.2years after the first implantation for better inter-chamber synchrony and ventricular function. Freedom from reoperation for generator change after the first implantation was 95.3, 70.6, and 21.9% at 1, 5, and 10 years. Eighteen (18) lead malfunction events (34.1%) were detected. Freedom from reoperation for lead change was 97.8, 76.2, and 46.3% at 1, 5, and 10 years. The lead replacement rate was significantly higher in patients with non-steroid-eluting than steroid-eluting leads (p=0.045).

CONCLUSIONS

Neonates and infants require more frequent changes in pacemaker generator and leads than the older population. The use of steroid-eluting leads increased lead longevity and reduced the need for surgical re-interventions.

Full Atrioventricular Block Secondary to Acute Poisoning Mercury: A Case Report

Background: The biological behaviour and clinical significance of mercury toxicity vary according to its chemical structure. Mercury differs in its degree of toxicity and in its effects on the nervous, digestive and immune systems as well as on organs such as the lungs, kidneys, skin, eyes and heart. Human exposure occurs mainly through inhalation of elemental mercury vapours during industrial and artisanal processes such as artisanal and small-scale gold mining. Case presentation: A 52-years-old female, housewife, with a body mass index of 25.3 kg/cm², without smoking or alcohol habits or any important clinical or chronic cardiovascular history, was admitted to the emergency room due to probable accidental poisoning by butane gas. Clinical manifestations with a headache, dizziness, cough, and dyspnoea of medium to small efforts. An initial physical exploration with Glasgow scored at 15, with arrhythmic heart sounds, pulmonary fields with bilateral subcrepitant rales and right basal predominance. Electrocardiographic findings were as follows: a cardiac frequency of 50 beats per minute and atrioventricular dissociation. Laboratory parameters were: white blood cells at 15.8 × 10⁸/L; aspartate aminotransferase at 38 U/L; lactate dehydrogenase at 1288 U/L; creatine-kinase at 115 U/L; CK-MB fraction at 28 U/L; and other biochemical parameters were within the reference values. A radiographic evaluation showed flow cephalization, diffuse bilateral infiltrates with right basal predominance. In addition, the patient presented data of low secondary expenditure to third-degree atrioventricular (AV) block for which the placement of a transvenous pacemaker was decided, substantially improving the haemodynamic parameters. Subsequently, after a family interrogation, the diagnosis of mercury inhalation poisoning was established. An initial detection of mercury concentration (Hg(0)) was carried out, reporting 243.5 µg/L. In view of this new evidence, mercury chelation therapy with intravenous calcium disodium ethylenediamine tetraacetic acid (CaNa₂·EDTA) was initiated. After 8-days of hospital stay, she presented a favourable evolution with both clinical and radiological improvements, so that the mechanical ventilation progressed to extubating. Subsequently, she was referred for cardiology because of her persistent 3rd-degree atrioventricular block, deciding to place a definitive bicameral pacemaker. The patient was discharged from the hospital 14 days after admission due to clinical improvements with mercury plasma levels at 5 µmol/L and a heart rhythm from the pacemaker. Conclusions: We show evidence that acute exposure to elemental mercury can affect the heart rhythm, including a complete atrioventricular blockage.

Marked First-Degree Atrioventricular Block and Pseudo-Pacemaker Syndrome in a Pediatric Patient

We describe a 17-year-old female who presented with 3 weeks of abdominal pain, exercise intolerance, and an episode of altered mental status found to have marked first-degree atrioventricular block. Exercise stress test and cardiac catheterization demonstrated pseudo-pacemaker syndrome, and a permanent pacemaker was placed. Following placement, she has resolution of symptoms and markedly improved exercise tolerance.

Exercise-induced Atrioventricular Block with Coronary Artery Stenosis that Appeared Five Years after Bypass Surgery

A 68-year-old man with a history of coronary artery bypass surgery was referred to our hospital because of pre-syncope on effort. During a treadmill exercise electrocardiogram test, the patient developed advanced atrioventricular block associated with dizziness. Coronary angiography revealed significant stenosis of the right coronary artery, which had not existed at the time of the bypass surgery. We implanted drug-eluting stents in the stenotic lesion, and an exercise test showed resolution of the atrioventricular block. Exercise-induced atrioventricular block is rare, and it is necessary to distinguish it from ischemic heart disease, especially in patients with a history of coronary artery disease.

[Venous thromboembolic complications in patients with cardiovascular implantable electronic devices]

The problem of venous thromboembolic complications (VTECs) in patients with cardiovascular implantable electronic devices (CIEDs) is extremely important today because of an annually increasing number of surgical interventions for life-threatening arrhythmias and chronic heart failure. There are hitherto no clearly defined reliable risk factors for VTECs due to heterogeneity of the available literature data. Some sources point to elevated thrombus formation in patients with a large number of electrodes, in repeat operative interventions, in the presence of a temporary pacemaker, in implantation on the left side, silicon cover of an electrode, others refute these facts. Still undetermined remains the choice of antithrombotic therapy for prevention and treatment of VTECs in this cohort of patients. Implantation of a VTEC may be accompanied by thrombosis of deep veins of the upper extremities up to the development of total occlusion of veins. In rare cases, thrombosis extends proximally, there appears superior vena cava syndrome which may require surgical treatment. Diagnosis of these diseases is complicated by their symptom-free course in the majority of cases. The most dangerous VTEC is pulmonary thromboembolism very commonly not accompanied by clinical symptomatology or taking its course under the mask of other more frequent diseases. Despite the fact that pulmonary thromboembolism with a source in the system of the superior vena cava is rarely massive, it may lead to the development of chronic postembolic pulmonary hypertension and to decreased quality of life. The article contains a review of the present-day literature and a clinical case report concerning the development of VTECs in a patient with a CIED in the form of thrombosis of the right internal jugular, subclavian and brachiocephalic veins, pulmonary embolism of small branches of the right pulmonary artery, suppuration of the pacemaker's bed and sepsis. Therapy with antibiotics, low-molecular-weight heparins, antiplatelet drugs and anti-inflammatory agents with regular sanitation of the pacemaker's bed turned out effective.

Isolated Left Subclavian Artery, Complete Atrioventricular Block, and Tricuspid Atresia in a Neonate

Isolated left subclavian artery is one of the rarer aortic arch anomalies. It has been associated with other congenital heart diseases, typically tetralogy of Fallot, double-outlet right ventricle, and atrial and ventricular septal defects. Its significant clinical implications include a left-to-right shunt from the vertebrobasilar system, which causes pulmonary overcirculation and subclavian steal. We present an unusual case of a premature infant who was diagnosed prenatally with congenital complete atrioventricular block and tricuspid atresia and was found to have an isolated left subclavian artery postnatally. The patient underwent implantation of a permanent single-chamber epicardial pacing system. To our knowledge, this combination of lesions has not been reported-and in our case, it influenced our surgical planning.

[Anesthetic Management for Pacemaker Implantation in a Child with Mitochondrial Diseases and Complete Atrioventricular Block]

A 12-year-old boy with mitochondrial encephalomy- opathy underwent pacemaker implantation for com- plete atrioventricular block. He was hospitalized as his general condition deteriorated. Furthermore, Holter electrocardiogram revealed rapid atrioventricular con- duction defect Anesthesia was induced with propofol, fentanyl, and rocuronium and maintained with continuous infusion of propofol and remifentanil with administration of fen- tanyl and rocuronium under neuromuscular monitoring during surgery. Bispectral index was monitored and maintained at approximately 40. He could not commu- nicate and had unstable circulation. Therefore, we pro- longed the anesthesia induction time. In addition, for the purpose of decreasing the amount of anesthetic required, an ultrasound-guided transversus abdominis plane block was performed. Throughout the periopera- tive period, neither cardiovascular instabilities nor pro- gression of metabolic acidosis and sudden body tem- perature increases were observed. Many important points must be considered when administering anesthesia to a child with mitochondrial disease. When we plan the anesthetic strategy, moni- toring, and so on properly, the appropriate anesthesia management can be performed.

[Left ventricular dyssynchrony in prolonged septal stimulation]

Pacemaker stimulation is associated with unpredictable severe cardiac events. We evaluated left ventricular mechanical dyssynchrony (LVMD) during prolonged septal right ventricular pacing. We performed 99mTc-MIBI gated-SPECT and phase analysis in 6 patients with pacemakers implanted at least one year before scintigraphy due to advanced atrioventricular block. Using V-Sync of Emory Cardiac Toolbox we obtained phase bandwidth (PBW) and standard deviation (PSD) from rest phase histogram. Clinical variables, QRS duration, rate and mode of pacing in septal right ventricle wall, chamber diameters, presence and extension of myocardial scar and ischemia and rest LVEF were recorded. Prolonged septal endocardial pacing is associated with marked LVMD, even when systolic function was preserved. More severe dyssynchrony was found in patients with impaired LVEF, higher left ventricle diameters, extensive infarct or severe ischemia than in patients with preserved LVEF (PBW: 177.3o vs. 88.3o; PSD: 53.1o vs. 33.8o). In the patients with ischemic heart disease and pacemaker, gated-SPECT phase analysis is a valid and potentially useful technique to evaluate LMVD associated with myocardial scar and to decide the upgrading to biventricular pacing mode.

[Third degree atrioventricular block in a young woman with congenital central hypoventilation syndrome]

Congenital central hypoventilation syndrome (CCHS) is a rare multisystem disorder characterized by autonomic nervous system dysfunction, which often manifests as failure to maintain ventilatory homeostasis during sleep. We present a case with a third degree atrioventricular block in a young woman with CCHS, which to our knowledge has not been seen before. As sudden death is known to occur among patients with CCHS, and it is under consideration to offer regularly monitoring of patients throughout childhood and adolescence.

Is conventional cardiac pacing harmful in patients with normal ventricular function?

BACKGROUND

Right ventricular pacing may be deleterious in patients with left ventricular dysfunction, but in patients with normal function the impact of this stimulation triggering clinically relevant ventricular dysfunction is not fully established.

OBJECTIVES

To evaluate the clinical, echocardiographic findings of patients with previously normal left ventricular function underwent implantation of a pacemaker.

METHODS

Observational, cross-sectional study with 20 patients, who underwent implantation of pacemaker, prospectively followed-up, with the following inclusion criteria: normal left ventricular function defined by echocardiography and ventricular pacing higher than 90%. Were evaluated functional class (FC) (New York Heart Association), 6-minute walk test (6MWT), B-type natriuretic peptide (BNP), echocardiographic assessment (conventional and dyssynchrony parameters), and quality of life questionnaire (QLQ) (SF-36). The assessment was performed at ten days (t1), four months (t2), eight months (t3), 12 months (t4) and 24 months (t5).

RESULTS

Conventional echocardiographic parameters and dyssynchrony parameters showed statistically significant variation over time. The 6MWT, FC, and BNP showed worsening at the end of two years. QLQ showed initial improvement and worsening at the end of two years.

CONCLUSION

The implantation of conventional pacemaker was associated with worsening in functional class, worsening in walk test, increased BNP levels, increased duration of QRS, and worsening in some domains of the QLQ at the end of two years. There were no changes in echocardiography measurements (conventional and asynchrony measures).

[Transplantation of pedicled autologous sinoatrial node tissue for treatment of complete atrioventricular block in dogs]

OBJECTIVE

To observe the changes of surface ECG and cell couplings between sinoatrial node cells and myocardial cells following transplantion of pedicled autologous sinoatrial node tissue graft into the right ventricle of a canine model of complete atrioventricular block.

METHODS

Ten healthy dogs were randomized into transplantation group and control group. Pedicled autologous sinoatrial node tissue grafts were transplanted into the right ventricle in the transplantation group, while the sinoatrial nodes were only excised in the control group after placement of temporary myocardial pacing wires. The changes of surface ECG were observed at 1, 2, 3 and 4 weeks postoperatively. At 4 weeks, complete atrioventricular block was induced in the dogs by radiofrequency ablation of the His bundle. The heart rate of the dogs in both groups were recorded after the injection of isoproternol (ISO) from the femoral vein, and the transplanted tissue graft was observed under optical and transmission electron microscopes.

RESULTS

No significant changes occurred in the surface ECG. All the dogs showed ECG waveforms specific of complete heart block after the ablation, and the ventricular heart rates were similar between the two groups (P>0.05). The ventricular heart rate did not undergo obvious changes after ISO injection (P>0.05). The transplanted pedicled autologous sinoatrial node survived in the dogs and the sinoatrial node cells established desmosome junctions with the myocardial cells, but the number of junctions was not sufficient to support heart pacing.

CONCLUSION

Desmosome junction can occur between ventricular myocardial cells and sinoatrial node cells at the edge of transplanted pedicled autologous sinoatrial node tissue.

Complete atrioventricular block and infective endocarditis in a patient with hypertrophic obstructive cardiomyopathy

A 62-year-old man with hypertrophic obstructive cardiomyopathy (HOCM) had complete atrioventricular (AV) block and subsequent cardiac standstill. A previous electrocardiogram revealed a bifascicular block pattern. Because he also suffered from infective endocarditis of the native aortic valve, surgical therapy (dual-chamber permanent pacing, myectomy of the left ventricular outflow tract, and valve replacement) was performed. Complete AV block unrelated to a procedure is a rare complication in patients with HOCM, but it may be life-threatening. Therefore, a pre-existing cardiac conduction disturbance should be specifically recognized as the aura of a higher degree of AV block.

Pacemaker implantation in a premature low weight newborn with critical congenital atrioventricular block

We describe a case of a preterm newborn with congenital complete atrioventricular block (CAVB), delivered for distress by cesarean section, and undergone, at 1295 grams of weight, to permanent pacemaker implantation. The pacemaker has been inserted between the upper left rectus abdominal muscle and the posterior rectus sheath and connected by two epicardial leads on the left ventricle wall. The procedure has been successfull.

[Incomplete pacemaker lead fracture revealed by superficial maneuvers]

A 75-year-old man presented to our department with a complaint of recurrent syncope episodes seven years after dual chamber pacemaker implantation due to complete atrioventricular block. His electrocardiogram obtained on presentation showed a normal dual-chamber pacemaker rhythm. The chest X-ray and pacemaker interrogation did not show any lead fracture or dysfunction. Twenty-four hour Holter monitoring revealed periods of failure to pacing. Superficial maneuvers over the skin resulted in an excessive increase in the ventricular lead impedance and pacing failure. The clinical course of the patient was uneventful after implantation of a new electrode to the right ventricular apex.

[Radiofrequency ablation and cardioneuroablation for AVNRT and atrioventricular block]

We describe a case of a 35 year-old woman with AVNRT and AVB successfully treated with radiofrequency ablation. Prior to the procedure, PR interval was very prolonged (420 ms) and second degree Wenckebach AV block during sinus rythm with heart rate below 80/min was seen. After the successful RF ablation an improvement in atrio-ventricular conduction with disappearance of Wenckebach periodicity was achieved. This case shows that there is a possibility of successful elimination of slow pathway with improvement in AV conduction.

Late atrioventricular block and permanent pacemaker implantation after heart transplantation

The need for permanent pacemaker implantation due to late atrioventricular (AV) block after heart transplantation is rare. A 59-year-old male patient underwent heart transplantation. He presented with syncope eight months after transplantation. Ambulatory 24-hour Holter monitoring showed predominant sinus rhythm with a mean heart rate of 74 bpm, intermittent second-degree AV block, and high-degree AV block with pauses of up to 10.6 seconds. Percutaneous transvenous endomyocardial biopsy yielded a histologic diagnosis of grade IA rejection according to the ISHLT (International Society of Heart and Lung Transplantation) scoring system. A permanent pacemaker with DDD-R mode was implanted via the left subclavian vein, and he was discharged on the following day without any complication.

[Permanent pacemaker implantation after heart surgery: incidence and indications]

BACKGROUND

New conduction disturbances requiring pacemaker implantation occur in about 1-3% of patients undergoing heart surgery. We reviewed our experience with patients undergoing heart surgery between the years 1993-2005 in order to identify predictors for pacemaker requirement.

METHODS

There were 4999 patients aged 64 +/- 12 years. Coronary bypass was performed in 3448 (69%), valve surgery in 831 (17%), combined procedures in 623 (12%), and other procedures in 97 (2%).

RESULTS

Overall, 72 (1.4%) patients required pacemaker implantation for the following indications: complete atrioventricular block (AVB) in 59, second degree AVB in 2, severe bradycardia (< 40 beats/min) in 9, first degree AVB with left bundle branch block (LBBB) in 1, and bifascicular block in 1. For patients undergoing aortic valve replacement, the incidence of pacemaker implantation was 5%. Multivariate analysis identified the following predictors for pacemaker implantation: LBBB, aortic valve replacement, and elevated CPK-MB levels after surgery.

CONCLUSIONS

Patients undergoing heart surgery will require a permanent pacemaker in about 1.4% of cases. Based upon the recognition of predictors for pacemaker requirement, we recommend early implantation in order to enable early mobilization and shorter hospital stay.