Transient AV Block Research Articles

Transcatheter Closure of Atrial Septal Defect Using Amplatzer Septal Occluder

Background and Objectives:Transcatheter occlusion (TCO) may be an alternative method for the surgical closure of a secundum atrial septal defect (ASD) below 20 mm in diameter. We performed this study in order to evaluate the safety and feasibility of an Amplatzer septal occluder for closing ASD bigger than 20 mm in diameter percutaneously. Subjects and Methods:Thirty three of 39 patients presenting with ASD were included in this study (3 patients with a large defect over 32mm and 3 with multiple defects were excluded). The median age was 8.6 years (2.2-54) and median weight was 27 kg (10.7-85). The mean defect size was 15±3 mm as measured by transthoracic echocardiogram, 17±5 mm by transesophageal echocardiogram, and 21±6 (11-32) mm by balloon stretched diameter. The balloon stretched diameter was larger than 20 mm in 20 of 33 patients. The mean Qp/Qs was 2.3±0.7. The mean device size was 22±6 mm and the mean fluoroscopic time was 13±7 min. Results:The device was successfully implanted in 29 of 33 patients. The 4 patients in which implantation failed showed a left disc protrusion into the right atrium. Three of these patients were treated surgically, and one underwent a successful second attempt of TCO 12 months after the first trial. Complete closure was obtained in 30 patients in follow-up. The complications encountered included;cobra-shaped deformity of the device (3), transient AV block (Wenckebach) (1), embolization of the radioopaque marker into the left atrial appendage (1), failure in the first device (1), and mild mitral regurgitation at 3 months followup due to device protrusion into the mitral valve (1). Conclusion:The Amplatzer septal occluder appears to be a promising device for TCO of ASD up to 32 mm in diameter, however, long-term follow-up in a large number of patients is warranted. (Korean Circulation J 2002;32(1):17-24)

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transient complete AV block during transcatheter ablation of a left posteroseptal anomalous pathway in a patient with previous history of ventricular septal defect patch closure

Transvenous catheter ice mapping and cryoablation of the atrioventricular node in dogs.

While radiofrequency catheter ablation is very effective, it does not allow for prediction of success prior to full delivery of the energy. We investigated the use of cryoablation using a new catheter on the AV node to determine (1) if a successful site might be identified prior to the ablation itself, and (2) the parameters of cryoablation of the AV node using a new cryocatheter. In eight dogs, the cryoablation catheter was advanced to the AV node to produce transient high degree AV block by lowering the temperature to a minimum of -40 degrees C (ice mapping). Transient high degree AV node block was obtained in seven of eight animals at a mean temperature of -39.9 +/- 11.6 degrees C. No significant pathological modification was found in all animals but one and, in all cases, electrophysiological parameters of the AV node measured before, 20 minutes, 60 minutes, and up to 56 days after cryoapplication were not significantly different. In the 12 other dogs, after ice mapping, cryoablation of the AV node was attempted with a single freeze-thaw cycle in 6 dogs (group I) and a double freeze-thaw cycle in the other 6 dogs (group II). Chronic complete AV block was obtained in only one animal in group I compared to all animals in group II. Ablation of the AV node is effective with a double freeze-thaw cycle using a percutaneous catheter cryoablation system. Ice mapping of the area allows for identification of the targeted site.

Anatomical Sites of the Successful Catheter Ablation Using the Anatomic Approach in Patients with AV Nodal Reentrant Tachycardia

Background and Objectives:Intracardiac electrocardiographic finding using as a guide for selective catheter ablation in patients with AV nodal reentrant tachycardia (AVNRT) is not specific. Therefore, we evaluated the efficacy and safety of the anatomical approach for catheter ablation in patients with AVNRT. Materials and Methods:Among the patients diagnosed as AVNRT by electrophysiologic study, total 66 patients (M:F= 26:40) were included in this study. In the right anterior oblique radiographic view, the septal annulus of tricuspid valve, extending from the most posterior region of the annulus adjacent to coronary sinus ostium (posterior) to His bundle recording site (anterior), was divided into posterior (P), mid (M), and anterior (A) sites. Radiofrequency (RF) energies were applied from the posterior part to the anterior part sequentially along the septal annulus of tricuspid valve until successful ablation. Results:Successful anatomical sites were located in posterior (11 patients), mid (48 patients), and anterior (7 patients) sites. The most patients (62 patients) were treated with slow pathway ablation except 4 patients in whom fast pathway was ablated. Probable slow potentials were observed in 8 patients (12%, 3 in posterior sites and 5 in mid sites). Transient complete AV block followed by first degree AV block and delayed complete AV block was occured in one case whose ablation site was A1. And another 3 patients had postablation first degree AV block. Conclusion: In patients with AVNRT, the ablated pathway were different according to successful anatomical site. And RF catheter ablation of atrioventricular nodal reentrant circuit guided by anatomical landmark is safe and efficacious. (Korean Circulation J 1999;29(2):174-181)

Myocardial perfusion scintigraphy (SPECT) during adenosine stress can be performed safely early on after thrombolytic therapy in acute myocardial infarction.

The objective of this study was to evaluate the safety of myocardial perfusion scintigraphy with Tc-99 m sestamibi during adenosine stress in patients with recent thrombolytically treated myocardial infarction. Eighty-four patients with thrombolytically treated myocardial infarction, 59 males and 25 females, aged 62.9 +/- 8.4, were eligible for myocardial perfusion scintigraphy during adenosine provocation. Exclusion criteria for adenosine stress were hypotension, unstable angina pectoris, cardiac failure, pericarditis and atrioventricular block (AV block) II-III. Adenosine-stress and resting myocardial perfusion scintigraphy was performed 2-5 days after thrombolysis. Scintigraphy at rest was done 24 h after the stress study. Sixty patients (71%) experienced some kind of side-effects during adenosine infusion. The most frequent side-effects were dyspnoea in 43/84 patients (51%) and unspecific chest discomfort in 26/84 patients (31%). During infusion, ST depressions or elevations on ECG were seen in 9 patients (11%), 5 of whom experienced atypical chest discomfort. Five patients (6%) described typical angina but none of them showed electrographic signs of myocardial ischaemia during infusion. Six patients (7%) developed transient AV block I-II. Reversible scintigraphic perfusion defects were seen in 67 patients (79%). No serious complications, such as death, reinfarction or severe arrhythmias, occurred during adenosine infusion or during a 3-day clinical follow-up period. In conclusion, MIBI-SPECT during adenosine stress is a safe diagnostic method that can be performed in most patients early on after thrombolytically treated acute myocardial infarction. Side-effects are common but benign, and not different from those seen in patients with chronic coronary artery disease.

Ausência de ventriculotomia previne arritmias ventriculares pós correção da tetralogia de Fallot?

Arritmias ventriculares são eventos tardios freqüentes após correção da tetralogia de Fallot (TF). Morte súbita, possivelmente relacionada a arritmias, é responsável por mais de 40% dos óbitos tardios. Fibrose cicatricial pela ventriculotomia direita poderia ser fator predisponente a eventos arrítmicos. A abordagem atrial teria vantagens por evitar lesão das coronárias, não comprometer a dinâmica ventricular e prevenir arritmias tardias. Trabalhos prévios demostraram não haver melhor desempenho hemodinâmico no procedimento pós-operatório imediato na correção atrial. Nesta série, procuramos analisar a incidência de arritmias ventriculares tardias no Grupo de correção atrial, comparativamente à ventriculotomia direita. Entre 1988 e 1995, 238 pacientes foram submetidos a correção cirúrgica da TF, sendo 28 por via exclusiva atrial (Grupo A) e 210 por via ventricular (Grupo V). Os grupos eram semelhantes quanto a idade, sexo, peso, altura e superfície corporal. A escolha da abordagem foi aleatória. Pacientes que sofreram qualquer ventriculotomia foram incluídos no Grupo V. Avaliamos a ocorrência de BAV transitório ou definitivo no p.o. imediato e a presença de arritmias atriais e ventriculares no ECG comum obtido na última consulta ambulatorial. O tempo de acompanhamento foi 45 ± 22 m no Grupo A e 33 ± 24 m no Grupo V. Não houve BAV transitório ou definitivo no Grupo A. Ocorreram 7% BAV transitórios e 2% definitivos no Grupo V (NS). Arritmias supraventriculares foram 17,4% no Grupo A e 12,0% no Grupo V (NS). Arritmias ventriculares foram 13,0% A e 3,8% V (NS). A evolução clínica quanto ao alívio da estenose pulmonar, eventos p.o. imediatos e classe funcional foi semelhante em ambos os grupos. Resultados publicados de mapeamento eletrofisiológico de VD demonstram anormalidade da despolarização, não apenas na parede livre, mas também no septo, banda parietal e ápex, sendo as arritmias ventriculares mais freqüentes e mais graves em casos da despolarização alterada no VD. Entretanto, não se encontra correlação entre arritmias e ventriculotomia. Concluímos que a abordagem atrial não previne a ocorrência de arritmias ventriculares no p.o. tardio de TF.

Transient complete atrioventricular block during radiofrequency ablation of slow pathway for atrioventricular nodal reentrant tachycardia

We conclude that most patients with transient AV block are clinically and electrocardiographically stable over a long follow-up time; thus, whether such patients will eventually have complete AV block is as yet unknown.

Autonomic Dysfunction After Catheter Ablation

Autonomic dysfunction may occur as a consequence of radiofrequency (RF) catheter ablation of a variety of supraventricular tachycardias. Effects suggestive of autonomic dysfunction that may be seen acutely during the ablation procedure include sudden profound slowing of the sinus rate or transient AV block. These abnormalities may occur during application of RF current, typically along the tricuspid or mitral annulus, at sites distant from both the sinus and AV nodes; they resolve quickly when RF current delivery is terminated. The most common long-term indication of autonomic dysfunction after ablation is inappropriate sinus tachycardia. This complication, rarely a lasting significant clinical problem, is seen after AV node modification and after ablation of accessory pathways. It usually resolves within several months. The mechanism appears to be loss of parasympathetic influence on the sinus node. Autonomic dysfunction after ablation of ventricular tachycardia has not yet been described, but could occur as newer catheter technologies capable of producing larger lesions are perfected.

Catheter ablation for the common type of atrioventricular nodal reentrant tachycardia.

Radiofrequency (RF) catheter ablation of the slow AV nodal pathway was attempted in 34 patients with common type of AV nodal reentrant tachycardia (AVNRT). Radiofrequency energy of 18-32 watts was applied for 30-60 seconds at sites exhibiting atrial-slow pathway potentials or slow potentials. These potentials were recorded at the mid or posterior septum, anterior to the coronary sinus ostium. A mean of two radiofrequency applications successfully eliminated AVNRT in all patients. The incidence of junctional ectopy was significantly higher during 34 effective applications of radiofrequency energy than during 36 ineffective applications (100% versus 17%). Thus, the recording of atrial-slow pathway potentials or slow potentials, and the development of junctional ectopy can be used as a marker for successful ablation. Slow AV nodal conduction was eliminated in 22 patients and persisted without inducible AVNRT in 12. None of the patients had recurrences of AVNRT over a mean follow-up interval of 12 months, and all had preserved AV conduction. Long-term follow-up studies with an electrophysiological method confirmed that the ablation was effective. Transient AV block was observed in only 1 patient, and no major complications were noted. Thus, radiofrequency catheter ablation of the slow AV nodal pathway is highly effective and safe, with a low rate of complication, for the treatment of common type of AVNRT.

Selective radiofrequency catheter ablation of the slow pathway for common and uncommon atrioventricular nodal reentrant tachycardia.

The utility of selective radiofrequency catheter ablation of the slow pathway for the treatment of common and uncommon atrioventricular nodal reentrant tachycardia (AVNRT) was studied in 110 consecutive patients, 94 with slow-fast form common AVNRT, and 11 and 5, respectively, with the fast-slow and slow-slow forms of uncommon AVNRT. Ablation sites were determined by mapping a late and spiky "slow pathway potential" in the posterior right atrial septum in common AVNRT, and also the earliest retrograde atrial activation over the retrograde slow pathway in uncommon AVNRT. AVNRT was successfully eliminated in all patients with a mean number of radiofrequency pulses of 2.9 +/- 3.0 and a mean total energy applied of 3536 +/- 2996 joules. There were no early or late complications, except for transient AV block for 15 sec immediately after energy application in one common AVNRT patient, and no recurrence of AVNRT in a mean follow-up period of 24 +/- 13 months. There were no significant differences between common and uncommon AVNRT in success rate, mean application number and total energy applied. However, the AVN physiology post-ablation was different. Slow pathway conduction was eliminated in only 32% of the patients post-ablation in common AVNRT, while it was elininated in 100% in uncommon AVNRT. Selective radiofrequency catheter ablation of the slow pathway can cure common and uncommon AVNRT effectively and safely. Common AVNRT can be eliminated irrespective of the persistence of slow pathway conduction, while uncommon AVNRT can be eliminated by the eradication of slow pathway conduction.

Early Rhythm Disorders after Arterial Switch and Intraatrial Repair in Infants with Simple Transposition of the Great Arteries

Between 1986 and 1990 68 infants with transposition of the great arteries (TGA) have been repaired within their first six months of life. From the 51 simple TGA, forming the study group, 20 underwent intraatrial repair according to Mustard and Brom (group I) and 31 received the arterial switch procedure (group II). We compared the observed rhythm disorders after both surgical methods. There were no deaths in group I and 3 deaths in group II. Group I: 7 cases (35%) had early postoperative arrhythmias, 6 patients received transient therapy. There were 3 cases of supraventricular tachycardia (SVT), 2 cases of frequent supraventricular premature beats (SVPB), 1 infant with temporary AV junctional rhythm and 1 with temporary total AV block. Both needed external pacemaker support for maximal two days. Group II: 14 cases (50%) presented rhythm disorders, 13 patients received transient therapy. There were 4 SVT and 3 SVPB. The time of occurrence was between the first and the sixth postoperative day. 2 cases of temporary AV junctional rhythm and 2 infants with transient total AV block needed external pacemaker support for maximal two days. 3 cases with relative sinus bradycardia (less than 130 beats/min) improved clinically with temporary external pacemaker support for several hours. Finally all patients of both groups were in sinus rhythm and after two months all antiarrhythmic drugs could be stopped. There have not been any ventricular arrhythmias in the early postoperative period. During the whole follow up (mean 28 months, range 4-60 m) no arrhythmias reappeared with two (4%) exceptions.

In vitro and in vivo modulation of multi-drug resistance with amiodarone.

The modulating effect on drug resistance of amiodarone (AM) and its metabolite desethylamiodarone (DEA) was studied in a P-glycoprotein-positive human colon carcinoma cell line COLO 320, and a human small-cell lung carcinoma cell line GLC4 and its adriamycin (Adr)-resistant subline GLC4-Adr (both P-glycoprotein-negative). AM, DEA and verapamil induced an increase in cytotoxicity of Adr, vincristine and etoposide (VP16) in COLO 320 cells, while in the GLC4 and GLC4-Adr cell line no effect was seen. In the COLO 320 cell line, AM caused more intracellular, and especially intranuclear, fluorescence of Adr and more Adr-induced DNA strand breaks as compared to Adr alone. Moreover, an increase in VP16-induced topoisomerase II-DNA complexes was observed when AM was added. Competition between AM and Adr for the same efflux pump was suggested in efflux studies. The colony-forming unit granulocyte macrophage (CFU-GM) assay showed no increase in cytotoxicity of Adr when AM was added. Fourteen patients with Adr-resistant tumors were treated with Adr and AM. In these patients, peak serum levels of AM plus DEA of 10 microM were reached. Patient serum (20%) obtained after the first i.v. AM infusion induced in vitro significantly more cell kill of Adr in COLO 320 cells. Apart from a transient first-degree AV block in one patient, no cardiac toxicity was observed with the combination of Adr and AM. Bone-marrow toxicity was the same as expected from Adr alone in these patients. One of the 13 evaluable patients obtained a partial remission.

ECG variants and cardiac arrhythmias in athletes: Clinical relevance and prognostic importance

These findings permit the following conclusions on cardiac changes induced by high-performance sports and high levels of training. Sinus bradycardia and AV block can frequently be observed in athletes, but they do not require attention as long as they are asymptomatic or do not produce pauses exceeding 4 seconds. Persistent rather than transient second-degree AV block or Mobitz second- or third-degree AV block is an extremely unusual finding even in athletes and should be considered a sign of organic lesions until proved otherwise. Supraventricular and AV node ectopic beats are not more frequent in athletes than in the general population except for atrial fibrillation. WPW syndrome is of particular importance, since rapid conduction to the ventricle via the accessory AV pathway is possible, especially if there is a tendency toward atrial fibrillation. Likewise caution is required in athletes with hypertrophic cardiomyopathy. Here hemodynamic deterioration must be anticipated with the occurrence of supraventricular tachycardia. Simple ventricular arrhythmias occur among athletes with the same frequency as in the general population, but they usually disappear with exercise. The occurrence of complex ventricular forms of arrhythmia should always prompt cardiologic examination in search of underlying cardiac disease, particularly hypertrophic or dilated cardiomyopathy. The presence of ventricular arrhythmias without evidence of underlying heart disease does not indicate a special or increased risk of sudden cardiac death. A higher incidence of right and/or left ventricular hypertrophy, exercise-reversible ST elevation, and exercise-reversible changes in T waves (T negativity, sharp and/or excessive T waves) can be considered physiologic changes in the ECGs of athletes. These changes correlate closely with the type of sports activity and degree of training and are reversible when the activity is stopped. Horizontal ST segment depression are by contrast very rare in athletes and should always be clarified by cardiologic examination. Exercise-induced sudden cardiac death in athletes is unusual without preexisting heart disease. The cause of sudden cardiac death among athletes less than 40 years of age can be predominantely ascribed to congenital heart diseases (such as hypertrophic cardiomyopathy or coronary anomalies). In athletes more than 40 years of age and with increasing age, coronary heart disease is the most frequent autopsy finding. A corresponding risk stratification should take these partial dangers into account.

Electrical ablation of junctional tachycardias showing a long RP interval.

Transvenous catheter ablation of the anomalous pathway was attempted in seven patients with drug-resistant repetitive long RP tachycardias. The patients were aged 5.5-65 years (median 20 years) and had received from four to seven antiarrhythmic agents without effect. Electrophysiological studies confirmed the anomalous substrate for tachycardia in five patients but in two patients an intranodal mechanism could not be excluded. Discharges were delivered to the coronary sinus ostium or low right atrium close to the ostium using conventional defibrillators (three patients) or a modified device (four patients). Transient AV block was seen after six attempts progressing to permanent block in one patient. In no patient could enduring block in the retrograde limb of tachycardia be achieved, and tachycardia recurred in all patients in whom anterograde conduction remained intact. The failure of selective ablation techniques in long RP tachycardia may reflect the diversity of substrate anatomy or particular properties (anatomical or functional) of the pathway compared with the usual types of anomalous pathway.

Catheter ablation of ventricular tachycardia using defibrillator pulses: electrophysiological findings and long-term results.

Catheter ablation of ventricular tachycardia (VT) was attempted in 24 patients (mean age 49 +/- 15.1 years) with a history of recurrent sustained VT resistant to previous antiarrhythmic drug therapy. 14 patients (58.3%) had also failed to respond to long-term administration of amiodarone alone and in combination with class I antiarrhythmic drugs. Endocardial catheter mapping during induced or spontaneous VT and/or pacemapping were performed to identify the site of origin of VT. Direct-current high-energy anodal shocks were delivered from a conventional cardioverter with stored energies of 100, 200 or 400 J via the distal electrode of conventional catheters. A total of 139 shocks was delivered during the ablation procedure. One patient died from wall perforation. Within 1 week of ablation, nine patients developed spontaneous recurrences of monomorphic sustained VT, identical to the clinical VT, and one patient developed a VT with a new morphology. In addition, four patients had a recurrence of their clinical VT after several weeks. In seven of 14 patients with spontaneous recurrences after the first ablation procedure and in three patients in whom VT was again inducible at the end of the first week, a second ablation procedure was performed. One patient with inducible VT after the first and second ablation sessions was given a third ablation procedure, and was discharged from hospital on anti-arrhythmic drugs which were successful despite being previously ineffective. After a mean follow-up period of 14.1 +/- 9.1 months, there were no spontaneous recurrences of sustained VT in 17 patients (71%) (nine without antiarrhythmic drugs and eight on antiarrhythmic drugs). In the remaining patients, incessant non-sustained VT (n = 2) or recurrent sustained VT (n = 2) occurred, and two patients died suddenly (at 2 and 21 months). There was no correlation between catheter mapping data or the results of pre-discharge electrophysiological study and clinical outcome during long-term follow-up. Complications related to catheter ablation included pulmonary oedema, cardiac tamponade, femoral artery occlusion, multiple episodes of ventricular tachycardia/fibrillation and thrombus formation, each in one patient (major complications; n = 7,29.1%), as well as transient third degree AV block, transient right or left bundle branch block, transient marked ST elevation or transient atrial tachycardia (minor complications; n = 8, 33.3%). The results suggest that catheter ablation might become an effective procedure for the non-pharmacological treatment of sustained VT.(ABSTRACT TRUNCATED AT 400 WORDS)

Endocardial Catheter Ablation for Refractory Ventricular Tachycardia Associated with Coronary Artery Disease

Percutaneous endocardial electrode catheter ablation using stored direct current (DC) electrical energy was performed in five patients with recurrent ventricular tachycardia (VT) refractory to many antiarrhythmic drugs, including amiodarone. All had prior myocardial infarction and poor left ventricular function with ejection fractions ranging from 20% to 40%. Endocardial catheter and pace mappings were used to localize the earliest site of activation during VT. Under general anesthesia, two to six shocks with 200 to 300 joules DC energy per shock were delivered to the localized sites. Immediate complications included ventricular fibrillation in one patient, transient QRS complex widening in two patients, transient complete AV block with persistent first-degree AV block in one patient, and transient asystole in two patients. None had inducible VT immediately following ablation, or 4 to 6 days later; none had evidence of intracardiac clot by two-dimensional (2D) echocardiography on the third to fifth day. Peak creatine kinase ranged from 189 to 1610 IU/L with 9% to 18% MB fraction. During a follow-up of 6 to 30 months, three patients had no recurrence of VT. Two patients had recurrent VT with a slower rate, which was controlled with antiarrhythmic drugs. None had worsening of congestive heart failure. Two patients died of nonarrhythmic causes. We conclude that nonsurgical endocardial ablation of VT with an electrode catheter is effective for the treatment of refractory VT in selected patients with coronary artery disease.

Transient first-degree av block and sixth nerve palsy in a patient with closed head injury

We present the case of an 8-year-old girl who suffered a closed head injury with the development of bilateral sixth-nerve palsies, and who was noted upon arrival to the emergency department to be in first-degree AV block. The sixth-nerve palsies and the first-degree AV block resolved simultaneously within 24 hours of injury. We discuss dysrhythmias and ECG changes previously reported with central nervous system diseases and their proposed etiology.

Sleep and Control of Heart Rate

The heart rate in normal humans is determined by many factors. Assuming a normal hemoglobin concentration, left ventricular function, and metabolic rate, respiration, and its effects, along with autonomic nervous activity, appear to influence heart rate the most. Hypoxia and hypercapnia both increase heart rate during wakefulness and probably do the same during sleep. The hypoxic response is dependent on information from lung inflation and the carotid bodies. Respiratory rate, within limits, will determine the amplitude of the well-known (respiratory) sinus arrhythmia. During sleep, a distinct pattern of heart rate response and its respiratory arrhythmia are seen for each stage of sleep and are related to the level of autonomic nervous system activity during wakefulness. Blood pressure follows the same trend as heart rate during sleep, and changes in cardiac output and total peripheral vascular resistance are variable during sleep, but there is no consensus of opinion about the direction of these changes. Rhythm disturbances are predominantly those of bradyarrhythmias, exaggerated sinus arrhythmias, and transient AV block, which are probably occurring in REM sleep.

Atrioventricular conduction abnormalities in patients undergoing isolated aortic or mitral valve replacement.

Cardiac conduction defects are common in patients with aortic valve disease. Several studies have suggested that the spontaneous occurrence of complete heart block in these patients is related to the extent of calcium deposits in the aortic valve and adjacent structures. No studies have been done to relate the occurrence of complete heart block at the time of valve replacement to predictive factors. We evaluated 102 consecutive patients undergoing isolated aortic valve replacement and 100 patients undergoing isolated mitral valve replacement. Although transient complete heart block was relatively common in each group (17.6% and 13%, respectively), we were not able to identify any factors predictive of its occurrence. There was a very low incidence of late heart block in a follow-up period of over four years. Thus, the capability for temporary pacing is mandatory in patients undergoing valve replacement. However, transient complete AV block during the perioperative period does not predict late recurrence of AV block and, therefore, prophylactic pacemaker or electrode implantation during or following transient block appears unnecessary.