Mesothelioma of the atrioventricular node and congenital complete heart block

Congenital complete heart block (CCHB) has heterogeneous etiologies. It may occur as an isolated entity with no associated congenital cardiac malformations and is difficult to diagnose even with modern technology. Mesothelioma of the atrioventricular (AV) node is a benign tumor that causes CCHB. The occurrence of this tumor is rare, and a definitive diagnosis of the entity is made only at autopsy. The conduction disturbance caused by the mesothelioma is potentially treatable and should be considered in the differential diagnosis of CCHB. We present a case report of a 38-year-old female with CCHB caused by such a tumor. Clinical diagnosis and treatment of CCHB are reviewed.     

Cerebral infarction in a patient with congenital complete heart block

Stokes-Adams attacks are fairly common in children with congenital complete heart block, but the occurrence of cerebral infarction is quite unusual. We present the case of a 13-year-old boy with congenital heart block and an embolic stroke involving the cerebral artery. Echocardiography revealed no valvular regurgitation, hypokinetic segments, mural thrombus, or myxoma. Electrocardiographic monitoring demonstrated good response of ventricular rate to exercise and no episodes of atrial or ventricular dysrhythmia. It is assumed that embolism occurred due to bradycardia.     

Measured versus predicted oxygen consumption in children with congenital heart disease

OBJECTIVE: To compare measured and predicted oxygen consumption (VO2) in children with congenital heart disease. DESIGN: Retrospective study. SETTING: The cardiac catheterisation laboratory in a university hospital. PATIENTS: 125 children undergoing preoperative cardiac catheterisation. INTERVENTIONS: VO2 was measured using indirect calorimetry; the predicted values were calculated from regression equations published by Lindahl, Wessel et al, and Lundell et al. Stepwise linear regression and analysis of variance were used to evaluate the influence of age, sex, weight, height, cardiac malformation, and heart failure on the bias and precision of predicted VO2. An artificial neural network was trained and used to produce an estimate of VO2 employing the same variables. The various estimates for VO2 were evaluated by calculating their bias and precision values. RESULTS: Lindahl's equation produced the highest precision (+/- 42%) of the regression based estimates. The corresponding average bias of the predicted VO2 was 3% (range -66% to 43%). When VO2 was predicted according to regression equations by Wessel and Lundell, the bias and precision were 0% and +/- 44%, and -16% and +/- 51%, respectively. The neural network predicted VO2 from variables included in the regression equations with a bias of 6% and precision +/- 29%; addition of further variables failed to improve this estimate. CONCLUSIONS: Both regression based and artificial intelligence based techniques were inaccurate for predicting preoperative VO2 in patients with congenital heart disease. Measurement of VO2 is necessary in the preoperative evaluation of these patients.     

Adenosine induced transient cardiac standstill in catheter interventional procedures for congenital heart disease

Objective—To describe the use of intravenous adenosine to create transient cardiac standstill during balloon dilatation procedures for congenital heart defects.
Setting—A tertiary paediatric cardiac centre.
Design and patients—This was a prospective pilot study. Thirteen patients born with congenital heart disease and who had stenotic lesions requiring relief were considered for the technique. All were suitable for balloon dilatation. Their ages ranged from 2 months to 30 years, mean (SD) 9.9 (9.8) years. The dose of adenosine varied from 0.125 mg/kg to 0.555 mg/kg, mean 0.33 (0.127).
Results—Two patients only developed sinus bradycardia in response to adenosine, which may have been related to the technique of administration. The other 11 experienced a period of asystole, which ranged from 2.4 to 10.8 seconds, mean 4.99 (2.27), and a total atrioventricular block period of 5.0 to 21.2 seconds, mean 9.47 (4.64). The interval between adenosine injection and the onset of asystole varied from 2.4 to 15.8 seconds, mean 8.05 (3.6), depending on cannula size, site of administration, and cardiac output. The peak gradient across the stenotic lesions fell from 52.3 (23.7) to 17.8 (11.9) mm Hg (p < 0.001). Apart from one short episode of atrial fibrillation there were no complications.
Conclusions—Intravenous adenosine is a safe and effective agent for creating transient cardiac standstill during balloon dilatation procedures for congenital heart disease. This achieves stability which is likely to improve results and reduce complications. It may have applications in other fields of cardiac intervention where an immobile heart is desirable during the critical phase of a procedure.

Keywords: adenosine;  asystole;  balloon dilatation;  congenital heart disease     

Dysrhythmias in patients with a complete atrioventricular septal defect: From surgery to early adulthood

Objective: Outcomes after surgical repair of complete atrioventricular septal defect (cAVSD) have improved. With advancing age, the risk of development of dysrhythmias may increase. The aims of this study were to (1) examine development of sinus node dysfunction (SND), atrial and ventricular tachyarrhythmias, and (2) study progression of atrioventricular conduction abnormalities in young adult patients with repaired cAVSD.
Study design: In this retrospective multicenter study, 74 patients (68% female) with a cAVSD repaired in childhood were included. Patients’ medical files were evaluated for occurrence of SND, atrioventricular conduction block (AVB), atrial and ventricular tachyarrhythmias.
Results: Median age at repair was 6 months (interquartile range 3‐10) and median age at last follow‐up was 24 years (interquartile range 21‐28). SND occurred after a me‐dian of 17 years (interquartile range 11‐19) after repair in 23% of patients, requiring pacemaker implantation in two patients (12%). Regular supraventricular tachycardia was observed in three patients (4%). Atrial fibrillation and ventricular tachyarrhyth‐mias were not observed. Twenty‐seven patients (36%) had first‐degree AVB, which was self‐limiting in 16 (59%) and persistent in 10 (37%) patients. One patient devel‐oped third‐degree AVB 7 days after left atrioventricular valve replacement. Spontaneous type II second‐degree AVB occurred in a 28‐year‐old patient. Both pa‐tients underwent pacemaker implantation.
Conclusions: Clinically significant dysrhythmias were uncommon in young adult pa‐tients after cAVSD repair. However, three patients required pacemaker implantation for either progression of SND or spontaneous type II second‐degree AVB. Longer follow‐up should point out whether dysrhythmias will progress or become more prevalent with increasing age.     

Occurrence of complete heart block associated with acute renal infarction

Complete heart block (CHB) and acute renal infarction (ARI) are both uncommon diseases and seldom encountered in the clinical practice. We describe a rare case of pre‐existing left bundle branch block, presenting simultaneously with CHB and ARI. The possible mechanism depends on prior presence of either CHB or ARI. If ARI occurs first, severe pain and embolism may enhance the vagal tone resulting in decrease in the heart rate and transient intraventricular conduction interruption, which subsequently causes CHB. The opposite scenario, CHB preceding ARI, is also possible. CHB can be physiologic and transient, with higher risk of development in the circumstance of pre‐existing conduction system disturbances. Patients with CHB are predisposed to formation of thrombi and thromboemboli, giving rise to ARI. In conclusion, awareness and timely identification of the clinical manifestations of these two diseases may facilitate early diagnosis and prompt management.     

Outpatient clinics for adults with congenital heart disease: increasing workload and evolving patterns of referral

OBJECTIVE: To examine the evolving role of specialised outpatient services for adult patients with congenital heart disease. DESIGN: A retrospective analysis of all patients attending the Toronto Congenital Cardiac Centre for Adults over three corresponding three month periods in 1987, 1992, and 1997. SETTING: A tertiary referral centre. MAIN OUTCOME MEASURES: Patient demographics, residence, medical and surgical history, type and source of referral, and investigations performed. RESULTS: In all, 570 patients were seen at the clinic during these three periods. There was a 44% and a 269% increase in workload between 1987 to 1992 and 1992 to 1997, respectively. There was a steady fall in mean age of patients seen at the clinic with time (38.5, 33.6, and 31.7 years in 1987, 1992, and 1997, respectively, p < 0.001). New referrals from community cardiologists and family physicians increased more in relative terms than did referrals from the Hospital for Sick Children, Toronto (6.7%, 15%, and 37.5%, p = 0.02). There was a steady increase in patients with previous reparative surgery (48.9%, 59.2%, and 69.2%, p < 0.002). The proportion of patients with previous reoperations also increased (2.3%, 10%, and 9.2%, p < 0.01). Echocardiography remained the predominant method of diagnosis. The diagnostic mix did not change with time. CONCLUSIONS: Over the past 10 years there has been a large increase in adults with congenital heart disease requiring and seeking specialised care in a tertiary health centre, with a concomitant evolution of referral patterns. These data may be helpful in planning of similar paediatric and adult cardiac services for this expanding population.     

Predictors of loss of atrioventricular synchrony in single lead VDD pacing

Objective—To evaluate maintenance of proper VDD function, defined as persistence of sinus rhythm with atrial synchronous ventricular pacing, and to define factors predicting failure of the VDD mode in patients with atrioventricular (AV) block and normal sinus function.
Design—Observational study in 86 consecutive patients (mean (SD) age 74 (12) years; 38 women, 48 men) with single lead VDD pacing systems (Intermedics Unity, n = 66, Medtronic Thera VDD, n = 20), implanted for high degree AV block with documented normal sinus node. Pacemaker function was assessed by event counters, telemetric measurements, and Holter recordings. Demographic, radiological, and pacing variables were correlated with loss of proper VDD function.
Results—During a mean (SD) follow up of 10 (10) months (range 1-37), sinus rhythm and atrial triggered ventricular pacing were maintained in 70 of 86 patients (81%). Atrial undersensing was observed in nine patients, lead migration in two, atrial fibrillation in three, and symptomatic sinus bradycardia in two. Univariate predictors of loss of proper VDD function were: low position of the atrial dipole relative to the carina ( 6 cm; p < 0.01) during fluoroscopy; and maximum programmable atrial sensitivity of the pacemaker (p = 0.03). In a multivariate analysis, only dipole position remained predictive of outcome (p < 0.02). Not predictive were sex, age, symptoms before pacemaker implantation, cardiothoracic ratio or dilatation of individual heart chambers on chest x ray, side of device implant, and P wave amplitude at implant.
Conclusions—To maintain proper VDD function in the long term, a low anatomical dipole position relative to the carina should be avoided. Electrical guidance of dipole positioning does not seem to influence long term outcome.

Keywords: VDD pacing;  atrioventricular synchrony;  arrhythmias     

The heart in limb girdle muscular dystrophy

Objective—To assess the frequency, nature, and severity of cardiac abnormalities in limb girdle muscular dystrophy, and its relation to age and weakness in various genotypes.
Design—In 26 autosomal dominant, 38 autosomal recessive, and 33 sporadic strictly defined patients with limb girdle muscular dystrophy, cardiac evaluation included history, physical examination, chest x ray, electrocardiography, 24 hour ECG Holter monitoring, and echocardiography. In 35 of the 71 autosomal recessive and sporadic cases muscle biopsies were available for sarcoglycan analysis.
Main results—Dilated cardiomyopathy was present in one autosomal dominant case and in three advanced autosomal recessive or sporadic patients, of whom two were found to have α sarcoglycan deficiency. Two of these three patients and three other cases showed ECG abnormalities known to be characteristic of the dystrophinopathies. A strong association between the absence of α sarcoglycan and the presence of dilated cardiomyopathy was found (p = 0.04). In six autosomal dominant cases there were atrioventricular (AV) conduction disturbances, increasing in severity with age and in concomitant presence of muscle weakness. Pacemaker implantation was necessary in four.
Conclusions—10% of these patients had clinically relevant cardiac abnormalities. In autosomal dominant limb girdle muscular dystrophy one subtype characterised by muscle weakness and AV conduction disturbances is recognised. In the course of autosomal recessive/sporadic limb girdle muscular dystrophy, dilated cardiomyopathy may develop, probably related to deficiency of dystrophin associated proteins.

Keywords: limb girdle muscular dystrophy;  cardiomyopathy;  AV conduction block;  sarcoglycan     

Exercise capacity in chronic heart failure is related to the aetiology of heart disease

Objective—To assess whether the underlying aetiology of chronic heart failure is a predictor of exercise performance.
Setting—Tertiary referral centre for cardiology.
Patients and outcome measures—Retrospective study of maximum exercise testing with metabolic gas exchange measurements in 212 patients with chronic heart failure who had undergone coronary angiography. Echocardiography and radionucleide ventriculography were used to determine indices of left ventricular function, and coronary arteriography was used to determine whether the cause of chronic heart failure was ischaemic heart disease (n = 122) or dilated cardiomyopathy (n = 90).
Results—The cardiomyopathy group was younger (mean (SD) age 58.45 (11.66) years v 61.49 (7.42); p = 0.02) but there was no difference between the groups in ejection fraction or fractional shortening. Peak oxygen consumption (O₂) was higher in the dilated group, while the slope relating carbon dioxide production and ventilation (E/CO₂ slope) was the same in both groups. Both groups achieved similar respiratory exchange ratios at peak exercise, suggesting that there was near maximum exertion. There was a relation between peak O₂ and age (peak O₂ = 33.9 − 0.267*age; r = 0.36; p < 0.001). After correcting for age, the peak achieved O₂ was still greater in the cardiomyopathy group than in the ischaemic group (p < 0.002).
Conclusions—Exercise performance for a given level of cardiac dysfunction appears to vary with the aetiology of heart failure. Thus the two diagnostic categories should be considered separately in relation to abnormalities of exercise physiology. The difference may in part account for the worse prognosis in ischaemic patients.

Keywords: exercise performance;  heart failure;  ischaemic heart disease;  dilated cardiomyopathy     

Accessory atrioventricular pathway, supra-, and infrahisian conduction impaired due to mitral annulus calcification

Disorders of conduction occurring simultaneously in both normal and accessory pathways of patients with Wolff-Parkinson-White (WPW) syndrome have only rarely been observed. To our knowledge this is the first report of impaired conduction in both pathways in WPW syndrome due to mitral annulus calcification (MAC). This case of WPW syndrome type A presented the following conduction abnormalities: (1) right bundle-branch block; (2) transient second-degree AV block with prolonged PR interval of the conducted beats; (3) during electrophysiological study, induction of tachycardia, dependent (phase 3) second-degree AV block, and occasionally conduction of two consecutive beats, the second showing an increased H-V interval (from 25 to 60 ms) and left bundle-branch block (LBBB) pattern, due to (4) infrahisian conduction abnormality.     

The falling mortality from coronary heart disease: a clinicopathological perspective

Objective—(1) To compare mortality estimates based on clinicopathological diagnoses of death from acute coronary heart disease with official estimates of coronary heart disease mortality; (2) to compare present day mortality figures with those from earlier reports.
Design—Prospective community study over the two years 1994 and 1995.
Setting—The health districts of Brighton, South Glamorgan, and York.
Subjects—1589 men and women under 75 years of age who, based on our study criteria, died from acute coronary events were compared with certified cases of coronary death in the same age group.
Main outcome measures—(1) Comparison of the underlying cause recorded on death certificates with the diagnosis of acute coronary death defined by our study criteria; (2) comparison of age specific mortality figures of the present with earlier studies.
Results—Up to age 65, age specific mortality for coronary heart disease, using study criteria, was similar to official estimates. However, at ages 65-74 years there was a shortfall in study deaths of about 20% compared with official figures. One reason for this was that many death certificates in elderly people attributed death to coronary disease in the absence of confirmatory evidence. Despite this, deaths in the under 65 age group in the 1990s appear to be occurring in people who are about 10 years older than was the case during the 1970s.
Conclusions—There are differences, most noticeable in elderly subjects, between estimates of coronary mortality made according to strict clinical and pathological definitions and official rates based on death certification. Recognition of these differences will be important for future epidemiological studies.

Keywords: mortality;  coronary heart disease;  clinicopathological diagnosis;  epidemiology     

预激综合征并发房室阻滞和束支阻滞PJ间期的分析

目的探讨预激综合征并发传导阻滞心电图PJ间期的变化。方法选经导管射频消融术（RFCA）治愈的显性预激综合征并发传导阻滞者10例,分为3组,即旁路（AP）位于束支阻滞（BBB）同侧组,旁路位于BBB异侧组及并发Ⅰ°房室阻滞（AVB）组。分别测量各组术前、术后的PJ间期并比较PJ间期变化。结果①6例旁路与BBB位于同侧的患者,术前PJ间期明显短于术后[（230±27）ms比（285±27）ms,P<0.01],但其中1例术前PJ间期为270ms（>260ms）;②2例AP与BBB位于异侧的患者,术前PJ间期短于术后（P<0.01）;③2例并发Ⅰ°AVB的患者,术前PJ间期明显短于术后PJ间期（P<0.01）。结论①预激综合征并发BBB时,PJ间期的变化取决于AP与正路的时差,AP与BBB的位置及AP距离心室最晚激动部位的远近,不能仅从AP的位置与BBB部位的关系来反映PJ的长短;②PJ间期的延长有可能为并发室内阻滞或AVB,宜进一步作食管心房调搏检查以明确诊断。     

Neck pounding during sinus rhythm: a new clinical manifestation of dual atrioventricular nodal pathways

Objective—To determine the clinical and electrophysiological characteristics of patients with paroxysmal palpitations and neck pounding during sinus rhythm.
Methods—Clinical, electrocardiographic, and electrophysiological characteristics of six patients with paroxysmal palpitations and neck pounding during sinus rhythm were studied in basal conditions and when symptomatic. Response to treatment was observed.
Results—Baseline ECGs were normal (four patients) or had first degree atrioventricular block with intermittent PR shortening. During symptoms, narrow QRS rhythms were seen without visible P waves (three patients) or with P waves partially hidden in the QRS complex (three patients). Dual atrioventricular nodal pathways were found in all five patients who had electrophysiological studies. In these patients the slow pathway conduction time was long enough (mean (SD), 425 (121) ms) for ventricular activation after slow pathway conduction during sinus rhythm to coincide with the next atrial depolarisation, causing neck pounding during exercise (four patients) or at rest (two patients). Tachycardia was not induced in any patient. Medical treatment aggravated symptoms in three patients. A pacemaker was successfully used in two.
Conclusions—Neck pounding during sinus rhythm is a clinical manifestation of dual atrioventricular nodal pathways. Medical treatment may aggravate symptoms but a pacemaker may offer definitive relief.

Keywords: neck pounding;  nodal conduction;  palpitations     

Exercise induced complete atrioventricular block: Utility of exercise stress test

Exercise induced complete atrioventricular block (EIAVB) is a relatively uncommon condition. This phenomenon is clinically important because it can mimic symptoms of other cardiovascular conditions and may be associated with exercise intolerance and subsequent syncope. A 76 year old man with long-standing hypertension and diabetes mellitus presented with recurrent episodes of lightheadedness and syncope with physical activity. ECG showed sinus rhythm with first degree atrioventricular block. Echocardiography did not show any valvular disease causing his symptoms. Coronoary angiographic evaluation revealed non-obstructive coronary artery disease. Because of the exertional nature of his symptoms, a symptom-limited treadmill exercise test was performed which revealed EIAVB. A permanent dual chamber pacemaker was implanted and his symptoms resolved completely.     

Spontaneous transition of 2:1 atrioventricular block to 1:1 atrioventricular conduction during atrioventricular nodal reentrant tachycardia: evidence supporting the intra-Hisian or infra-Hisian area as the site of block

INTRODUCTION: The incidence of spontaneous transition of 2:1 AV block to 1:1 AV conduction during AV nodal reentrant tachycardia has not been well reported. Among previous studies, controversy also existed about the site of the 2:1 AV block during AV nodal reentrant tachycardia. METHODS AND RESULTS: In patients with 2:1 AV block during AV nodal reentrant tachycardia, the incidence of spontaneous transition of 2:1 AV block to 1:1 AV conduction and change of electrophysiologic properties during spontaneous transition were analyzed. Among the 20 patients with 2:1 AV block during AV nodal reentrant tachycardia, a His-bundle potential was absent in blocked beats during 2:1 AV block in 8 patients, and the maximal amplitude of the His-bundle potential in the blocked beats was the same as that in the conducted beats in 4 patients and was significantly smaller than that in the conducted beats in 8 patients (0.49 +/- 0.25 mV vs 0.16 +/- 0.07 mV, P = 0.007). Spontaneous transition of 2:1 AV block to 1:1 AV conduction occurred in 15 (75%) of 20 patients with 2:1 AV block during AV nodal reentrant tachycardia. Spontaneous transition of 2:1 AV block to 1:1 AV conduction was associated with transient right and/or left bundle branch block. The 1:1 AV conduction with transient bundle branch block was associated with significant His-ventricular (HV) interval prolongation (66 +/- 19 ms) compared with 2:1 AV block (44 +/- 6 ms, P < 0.01) and 1:1 AV conduction without bundle branch block (43 +/- 6 ms, P < 0.01). CONCLUSION: The 2:1 AV block during AV nodal reentrant tachycardia is functional; the level of block is demonstrated to be within or below the His bundle in a majority of patients with 2:1 AV block during AV nodal reentrant tachycardia, and a minority are possibly high in the junction between the AV node and His bundle.     

Predictors of atrial rhythm after atrioventricular node ablation for the treatment of paroxysmal atrial arrhythmias

OBJECTIVE: To assess the natural history of the atrial rhythm of patients with paroxysmal atrial arrhythmias undergoing atrioventricular node ablation and permanent pacemaker implantation. DESIGN AND SETTING: A retrospective cohort study of consecutive patients identified from the pacemaker database and electrophysiology records of a tertiary referral hospital. PATIENTS: 62 consecutive patients with paroxysmal atrial arrhythmias undergoing atrioventricular node ablation and permanent pacemaker implantation between 1988 and July 1996. MAIN OUTCOME MEASURES: (1) Atrial rhythm on final follow up ECG, classified as either ordered (sinus rhythm or atrial pacing) or disordered (atrial fibrillation, atrial flutter or atrial tachycardia). (2) Chronic atrial fibrillation, defined as a disordered rhythm on two consecutive ECGs (or throughout a 24 hour Holter recording) with no ordered rhythm subsequently documented. RESULTS: Survival analysis showed that 75% of patients progressed to chronic atrial fibrillation by 2584 days (86 months). On multiple logistic regression analysis a history of electrical cardioversion, increasing patient age, and VVI pacing were associated with the development of chronic atrial fibrillation. A history of electrical cardioversion and increasing patient age were associated with a disordered atrial rhythm on the final follow up ECG. CONCLUSIONS: Patients with paroxysmal atrial arrhythmias are at high risk of developing chronic atrial fibrillation. A history of direct current cardioversion.     

Prevalence of ventricular preexcitation in Japanese schoolchildren

Background—Wolff-Parkinson-White syndrome is thought to be a congenital disease, however, its exact prevalence is not known. This may be because of the intermittent activity of accessory pathways in some cases and fluctuations in autonomic tone.
Aims—To investigate the prevalence of ventricular preexcitation by electrocardiography and reported symptoms in each school age child in Yamanashi prefecture.
Methods—From 1994 to 1996, answers to a questionnaire, results of physical examination, and electrocardiography were obtained from all schoolchildren in Yamanashi prefecture (n = 92 161; total population 880 000) on admission to elementary school (age 6 to 7 years, n = 28 395), junior high school (age 12 to 13 years, n = 31 206), and high school (age 14 to 15 years, n = 32 837).
Results—Elementary and junior high school students had a significantly lower prevalence of preexcitation than high school students (0.073% and 0.070% v 0.174%, p < 0.001). The prevalence of left free wall pathway was highest in high school students (n = 27) compared with elementary (n = 6) and junior high school students (n = 5) (p < 0.005). The only symptom noted in the answers to the questionnaire was palpitations. The symptomatic cases were more frequent in high school (n = 13) than in elementary (n = 1) and junior high school (n = 2) children, but not significantly. No student with preexcitation had associated heart disease or family history of Wolff-Parkinson-White syndrome or sudden death.
Conclusions—The prevalence of preexcitation in younger schoolchildren was less frequent than previously reported. The prevalence of preexcitation and left free wall pathways increased with age. The symptoms were few and there was no significant morbidity.

Keywords: preexcitation;  Wolff-Parkinson-White syndrome;  children;  epidemiology