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[A complete atrioventricular block during exertion].

Exercise-induced atrioventricular (AV) block in patients with normal electrocardiogram at rest is uncommon. We report the clinical features of two patients with AV block during treadmill test. The first patient was a woman of 54 years of age with presyncope on exercise. She developed complete AV block during exercise testing without evidence of ischemic myocardial disease. Electrophysiologic study documented distal AV block. The second patient was a man 31 years old who developed angina and third-degree AV block with depression of ST segment during treadmill test. Myocardial perfusion study suggested ischemic heart disease. He received anti-ischemic drugs with improvement of symptoms. A control exercise testing demonstrated normal AV conduction and electrophysiologic study was normal. In the first case, exercise AV block was probably due to abnormal His Purkinje conduction system refractoriness to autonomic modulation, while in second case AV block was secondary to ischemic heart disease. Third-degree AV block at exercise can be present in patients without conduction system abnormalities at rest. Exercise-induced infra-Hisian AV block must be treated with pacing until ischemic heart disease has been ruled out.

Adult↗

Nonsurgically-acquired complete atrioventricular block in endocardial cushion defect.

Complete atrioventricular heart block (CAVB) most commonly occurs as a complication of cardiac surgery. We report the development of CAVB in an 8-year-old girl with endocardial cushion defect (ECD) who had not undergone a cardiac operation. Although this is the first report of acquired non-surgical CAVB in a child with ECD, we believe that the development of CAVB in patients with unoperated ECD occurs more commonly than is usually realized. An increased awareness of this possibility will allow expedient diagnosis, which is essential to proper treatment. In most cases, the implantation of a permanent ventricular pacemaker will alleviate congestive heart failure or prevent sudden death.

Journal Article↗

Congenital complete atrioventricular block.

The various etiologies, pathologic findings, clinical concerns, and features of congenital complete atrioventricular block are presented and discussed. In addition, prenatal and antenatal diagnostic techniques are explained and analyzed. Lastly, treatment and the issues involved in deciding proper treatment are discussed in such a way that the general pediatrician can help the family to understand and handle the problem.

Autoimmune Diseases↗

Cause of atrioventricular block in patients after heart transplantation.

BACKGROUND: The precise incidence and cause of atrioventricular block (AVB) after heart transplantation remain uncertain. METHODS AND RESULTS: After surgery, immediate and follow-up electrocardiograms from 1047 consecutive patients who underwent heart transplantation were reviewed for AVB and correlated with clinical symptoms, laboratory data, rejection grade, and echocardiogram and coronary angiography findings. A total of 113 patients demonstrated various kinds of AVB; the incidence was 10.8%. First-degree AVB occurred in 87 patients, 37 of whom also demonstrated persistent atrial tachyarrhythmias (ATAs). In 30 patients, first-degree AVB occurred 7 days to 120 months after heart transplantation. Among those, 88% demonstrated cellular rejection, and 20% developed transplant coronary artery disease (TCAD). Fifty patients demonstrated first-degree AVB without ATA, 32 of whom developed AVB from operative day 7 to 156 months. The incidence of cellular rejection was significantly lower (36%, P<0.01), and the rejection was less severe. In 18 patients, AVB occurred early postoperatively (0-7 days), and most were secondary to surgical injury. Second-degree AVB Mobitz I occurred in six patients (four patients with TCAD and two patients undergoing percutaneous transluminal coronary angioplasty). One patient developed Mobitz II during coronary artery stenting. Complete AVB (CAVB) occurred in 19 patients. Nine episodes of CAVB occurred during endomyocardial biopsy or coronary angiography, and four occurred immediately after heart transplantation as the result of surgical insult. CONCLUSION: These results indicate that first-degree AVB is causatively related to cellular rejection and TCAD-induced atrial conduction disturbance. Second-degree AVB and CAVB were mainly the consequences of surgical and catheter intervention injury.

Anti-Arrhythmia Agents↗

Atrioventricular block during upright tilt table test.

Patients with a cardioinhibitory response (asystole or atrioventricular block [AVB]) during upright tilt table test (UTT) constitute a therapeutic challenge. Our present knowledge is partial and in those who experience AVB is absent. Furthermore, we ignore if there is any difference between both groups, particularly pacemaker indication. We aimed to study patients with a cardioinhibitory response during UTT and incidence of AVB during UTT, compared to asystole; plus the outcome during prolonged follow-up. Of 867 patients who underwent UTT, 172 were positive for a neurally mediated response, all with normal neurocardiovascular evaluation. Of the 172 patients, 6 (3.4%) developed AV block (group A), and 26 (15.1%) experienced asystole (group B). Group A included 6 women (100%), mean age 21 +/- 12 years. All patients in group A had sinus rate deceleration during AVB. Group B included 10 women (38%), mean age 28 +/- 17 years, and a mean pause of 15 +/- 9 seconds. We contacted 30 of 32 patients, mean follow-up of 45 +/- 38 months. Seven patients in group B had syncopal recurrences; five had 2 or more episodes. One patient from group B received a DDD pacemaker. In group A, one had one recurrence. No deaths were observed. AVB during UTT is rare, occurs in young women, and is always associated with sinus rate deceleration. Medium- to long-term prognosis is good, and equivalent to patients with asystole. There is no evidence that patients with AVB during UTT require a pacemaker implant.

Adolescent↗

Isolated congenital complete atrioventricular block in adult life. A prospective study.

BACKGROUND: The prognosis of congenital complete atrioventricular block (CCHB) is usually considered favorable in adults. This belief is based on studies comprising a limited number of patients and with rather short observation times. In the present study, the natural history of the disease was investigated by a prospective follow-up through decades of adult life of patients with a large group having well-defined CCHB without structural heart disease. METHODS AND RESULTS: The diagnostic criteria of CCHB proposed by Yater were applied. Patients registered as having CCHB in 1964, supplemented by younger patients all without symptoms during their first 15 years of life, were selected. The study was limited to patients with isolated, complete, permanent block. An interview was conducted with all patients and clinical follow-up data obtained. There were finally 102 patients, 61 women and 41 men. In November 1994, the time of observation, after the age of 15 years in survivors, was between 7 and 30 years. The mean age at follow-up or at death was 38 years, median age 37 years, and range 16 to 66 years. Stokes-Adams (SA) attacks occurred in 27 patients, in 8 with a fatal outcome. The first attack was fatal in 6 of these 8 patients. Nineteen survived and a pacemaker (PM) was implanted thereafter. Another 8 patients received a PM because of repeated fainting spells, and 27 others have had a PM implanted for other reasons such as fatigue, effort dyspnea, dizziness, ectopies during exercise tests, mitral regurgitation, and a low ventricular rate (VR). VR decreased with age, with a mean rate at 15 years of 46 beats per minute (bpm), at 16 to 20 years of 43 bpm, at 21 to 30 years of 41 bpm, at 31 to 40 years of 40 bpm, and after 40 years of age of 39 bpm. SA attacks occurred in all 7 patients with prolonged QTc time. Low VR at rest or at work, presence of bundle-branch block pattern, low working capacity, and ectopies at rest and/or during effort were not statistically significant risk factors. SA attacks occurred in 6 patients without any of these signs. Mitral regurgitation developed in 16 patients and 4 died. A PM reduced the risk of death. A change to a lower degree of block occurred in 6 patients. CONCLUSIONS: Prophylactic PM treatment is recommended even for symptom-free adults with CCHB because of the high incidence of unpredictable SA attacks with considerable mortality from first attacks, a gradually decreasing VR, significant morbidity, and a high incidence of "acquired" mitral insufficiency.

Adolescent↗

Cellular basis of biventricular hypertrophy and arrhythmogenesis in dogs with chronic complete atrioventricular block and acquired torsade de pointes.

BACKGROUND: In the dog with chronic complete atrioventricular block (AVB), torsade de pointes arrhythmias (TdP) can be induced reproducibly by class III antiarrhythmic agents. In vivo studies reveal important electrophysiological alterations of the heart at 5 weeks of AVB, resulting in increased proarrhythmia. Autopsy studies indicate the presence of biventricular hypertrophy. In this study, the cellular basis of proarrhythmia and hypertrophy in chronic AVB was investigated. METHODS AND RESULTS: From chronic-AVB dogs with increased heart weights and TdP, left midmyocardial and right ventricular myocytes were isolated by enzymatic dispersion. These myocytes were significantly larger than sinus rhythm (SR) controls. In chronic AVB, the action potential spike-and-dome configuration was preserved. However, the action potential duration (APD) at 95% and 50% of repolarization of the left midmyocardium was significantly larger in chronic AVB than in SR, with little change in the right ventricle, causing enhanced interventricular dispersion of repolarization at slow pacing rates. Treatment with the class III agent almokalant increased the APD to a much larger extent in chronic-AVB than in SR myocytes and resulted in a higher incidence of early afterdepolarizations (EADs). EADs had their takeoff potential between -35 and 0 mV. There was no evidence that spontaneous sarcoplasmic reticulum Ca2+ release underlies these EADs. CONCLUSIONS: In the dog, chronic AVB leads to hypertrophy of both right and left ventricular myocytes. The repolarization abnormalities predisposing for class III-dependent TdP in vivo are the results of cellular electrophysiological remodeling.

Action Potentials↗

Entrapment of a tined lead by the chiari network with preserved atrial sensing ability in a patient with atrioventricular block: a case report.

An 82-year-old woman with 2:1 atrioventricular block underwent a pacemaker implantation procedure, but a tined lead became entrapped by the Chiari network. All manipulations failed to achieve release of the electrode, by which the atrial electrical potential could be recorded. Tines equipped near the tip of a pacemaker lead are intended to prevent dislodgment, but entrapment of the tined tip by intracardiac structures is probable. Together with another screw-in ventricular lead, this entrapped tined lead could act as a dual chamber pacemaker in VDD mode.

Aged↗

Immediate prognostic significance of complete atrioventricular block in acute myocardial infarction.

To discern the relative prognostic role of complete atrioventricular block (CAVB) in patients with acute myocardial infarction (AMI), 908 consecutive patients with AMI were studied over a 7-year period. Of the 559 patients with anterior wall AMI, 13 (2.3%) demonstrated CAVB, of whom 10 (76.9%) died in the hospital (vs 10.4% in those without CAVB) (p less than 0.001). In 349 patients with inferior wall AMI, 30 (8.6%) developed CAVB, of whom 6 (20%) died (vs 6.3% in those without CAVB) (p less than 0.01). In anterior wall AMI, all 5 patients with narrow QRS complexes (vs 8/11 with wide QRS complexes) (p = NS) died; in inferior wall AMI, 4/25 with narrow QRS complexes (vs 2/5 with wide QRS complexes) (p = NS) died. The mortality rate of patients with an escape frequency of less than or equal to 50/min did not differ significantly from that of patients with greater than 50/min regardless of the site of infarction or whether a pacemaker was used. In anterior wall AMI, the mortality rate of paced patients was 70% (7/10) compared to 100% (3/3) of non-paced patients (p = NS). In inferior wall AMI, the mortality rate of paced (5/25) and non-paced (1/5) patients was both 20%. Thus, none of the clinical parameters such as escape rhythm, the width of escape QRS complexes and pacemaker therapy discriminated the survivors from the deaths. In anterior wall AMI, episodes of cardiac standstill or bradycardia were of short duration, and pacemaker therapy was only one of the therapies applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

[Lymphangioendothelioma. A rare cause of atrioventricular block].

A new case of lymphangio-endothelioma of the nodal tissue is reported. Complete atrioventricular block had been followed up for 20 years. The histological features are described in detail and the embryological origins of the tumour are discussed. This report underlines the exceptional character of this "smallest benign tumour which can be mortal".

Adult↗

Effects of dibutyryl cyclic AMP on ventricular vulnerability during atrioventricular block in dog.

The effects of dibutyryl cyclic AMP (DBcAMP) on ventricular vulnerability during complete atrioventricular block (CAVB) were studied one week after transarterial electrical ablation of the AV junction in 18 closed-chest dogs. All dogs exhibited CAVB and a stable ventricular escape rhythm with a mean cycle length of 1812 +/- 638 ms. After the administration of DBcAMP at a rate of 0.1 mg/kg/min for 30 min, the ventricular cycle length was significantly shortened, and the QTc interval was slightly prolonged, although the QT interval did not change. The ventricular fibrillation threshold after the administration of DBcAMP was significantly increased (from 12.2 +/- 3 84 to 18.4 +/- 5.08 mA, p less than 0.01). Thus, it was demonstrated that DBcAMP exhibited suppressive effects on the ventricular vulnerability in the experimentally induced CAVB.

Animals↗

Radiofrequency catheter ablation of a posteroseptal accessory pathway along the morphologic tricuspid valve in a patient with congenitally corrected transposition of the great arteries and complete atrioventricular block.

We report a patient with Congenitally Corrected Transposition of the Great Arteries, complete atrioventricular block and a posteroseptal accessory pathway across the morphologic tricuspid valve. Ablation of the accessory pathway was performed for her symptomatic palpitations.

Abnormalities, Multiple↗

Total atrioventricular block with syncopes complicating carbamazepine therapy.

At case of carbamazepine-induced intermittent total atrioventricular block with asystole and Stokes-Adams attacks is reported. The diagnosis was proved by repeated administration of carbamazepine after insertion of a demand pacemaker. If syncopes occur or change nature in a patient treated with carbamazepine, evaluation of cardiac conduction is recommended.

Adams-Stokes Syndrome↗

Prognosis of patients paced for chronic atrioventricular block.

Between the years 1960 and 1974, 839 patients were paced for chronic complete atrioventricular block. Analysis of survival compared with the general population showed that 170 deaths were expected according to standard mortality tables and 288 actually occurred, giving a ratio of actual to expected deaths of 1.7:1. Patients with a definite history of myocardial infarction showed a higher than average mortality when paced. Mortality was not influenced whether heart was constant or intermittent, whether the ventricular rate was below or above 40/minutes, or whether QRS duration was greater or less than 0.1 second. Analysis of the age groups paced disclosed the most important correlations. Between the ages of 80 and 89 years paced patients could expect to survive as long as other of the same age without heart block. There was, however, a very high ratio of 4.5:1 for 90 patients in the age group 50 to 59 years. The reason for the high mortality ratio was uncertain but it may have been the result of a greater incidence of underlying coronary artery disease.

Age Factors↗

Atrioventricular nodal reentrant tachycardia with advanced infra-hisian atrioventricular block.

We report a case of 78-year-old man admitted to the hospital due to palpitations and lightheadedness. On EKG advanced atrioventricular block with ventricular rate of 37 beats per minute was noted. On electrophysiology study a common type of atrioventricular nodal reentrant tachycardia was inducible with maintenance of advanced AV block. Radiofrequency ablation of slow pathway followed by placement of a permanent pacemaker resulted in elimination of tachycardia and resolution of symptoms.

Aged↗