Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia, and its diagnostic and therapeutic approaches have been well-established. Traditionally, AVNRT is understood to be an intranodal reentry having two bystander pathways; the upper common pathway (UCP) which connects to the atrium and the lower common pathway which connects to the ventricle. However, the existence of the UCP remains a subject of ongoing debate. The assertion of the UCP\'s presence is supported by electrophysiological evidence suggesting that the atrium is not essential for the perpetuation of AVNRT. Nonetheless, numerous anatomical studies have failed to identify any structure that could be conclusively designated as the UCP. The histological and electrophysiological characteristics of the slow and fast pathways, which are the core components of AVNRT, suggest the inclusion of atrial myocardium in the reentry circuit. While clear interpretation of these discrepancies remains elusive, potential explanations may be derived from existing evidence and recent research findings concerning the actual AVNRT circuit.

Maternal autoimmune disease is the most common cause of congenital heart block (CHB), a rare illness characterized by fibrosis and calcification of the fetal atrioventricular (AV) node due to maternal autoantibodies anti-SSA/Ro and anti-SSB/La. We report the full autopsy and clinical information on a female neonate with high degree AV block and calcification in the AV node, atrial approaches to the AV node, and both right and left bundle branches, born to a 27-year-old female with subclinical autoimmune disease.

Pseudo-pacemaker syndrome (PPMS) is a rare complication of first-degree atrio-ventricular (AV) block in which a very prolonged PR interval causes AV dyssynchrony and subsequent symptoms of hemodynamic instability in the absence of an implanted pacemaker. The aim of this manuscript was to describe a unique case of PPMS and to provide a comprehensive review of the topic to help clinicians in the diagnosis and management of this condition. Through systematic research on PubMed, Google Scholar, EBSCO, and Ovid MEDLINE and using the search strings \"pseudo-pacemaker syndrome\" and \"symptomatic first-degree AV block,\" we identified 14 articles accounting for 17 cases of PPMS, including our case report. The most common age group for PPMS was middle-aged and young adults, with an average age of 47 years. Palpitations were the most common presenting symptom and four main etiologies of PPMS were identified, as follows: (1) Idiopathic PPMS with evidence of impaired conduction over the AV node (20% of cases), (2) PPMS associated with reversable inflammatory causes (13%) or (3) associated with iatrogenic surgical or interventional procedures leading to the permanent damage of the normal AV conduction system (20%), and, finally, (4) PPM related to dual AV nodal physiology (DAVNP) as a primary finding (27%) or occurring after fast or slow pathway ablation for treatment of AV nodal re-entrant tachycardia (AVNRT) (20%). Treatment should be patient-tailored and based on the specific etiology once identified. However, the treatment of PPMS due to DAVNP without AVNRT presentation is yet to be clarified.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most frequent regular tachycardia in humans. In this review, we describe the most recent discoveries regarding the anatomical, physiological, and molecular biological features of the atrioventricular junction that could underlie the typical slow-fast AVNRT mechanisms, as these insights could lead to the proposal of a new theory concerning the circuit of this arrhythmia. Despite several models have been proposed over the years, the precise anatomical site of the reentrant circuit and the pathway involved in the slow-fast AVNRT have not been conclusively defined. One possible way to evaluate all the hypotheses regarding the nodal tachycardia circuit in humans is to map this circuit. Thus, we tried to identify the slow potential of nodal and inferior extension structures by using automated mapping of atrial activation during both sinus rhythm and typical slow-fast AVNRT. This constitutes a first step toward the definition of nodal area activation in sinus rhythm and during slow-fast AVNRT. Further studies and technical improvements in recording the potentials of the atrioventricular node structures are necessary to confirm our initial results.

心房颤动是成年人中最常见的持续性心律失常，心房颤动伴快速心室率是引起心力衰竭的重要原因之一。房室结消融联合希氏-浦肯野系统起搏是可行、有效的，尤其适用于难以耐受药物治疗或药物治疗无效、导管射频消融治疗失败的心房颤动伴快速心室率合并心力衰竭的患者。本文对房室结消融联合希氏-浦肯野系统起搏治疗心房颤动伴快速心室率合并心力衰竭的研究进展作一综述。.

Atrioventricular node reentrant tachycardia (AVNRT) is the most common mechanism of supraventricular tachycardia. Radiofrequency ablation has been the most prevalent method for slow pathway ablation but carries risk of atrioventricular node injury. Focal cryoablation has been utilized as an alternative ablation modality; however, there has been concern about decreased efficacy, resulting in a higher rate of recurrence postablation. We also report outcomes from two international centers using an 8-mm cryocatheter and complete a thorough comparison of existing data on ablation of AVNRT.
Previous reviews included studies from 2006 onward. These studies included use of the 4 mm focal cryocatheter, which has largely been abandoned in current adult practice. We will cite more contemporary studies within the past 10 years, which also includes use of the 6 and 8 mm cryocatheter.
The use of focal cryoablation allows for reversible injury during AVNRT ablation, providing safety from permanent atrioventricular node injury. With the appropriate ablation endpoints, 8 mm focal cryoablation is more effective for permanent lesion formation, leading to lower recurrences.

Transvenous pacemakers are associated with a significant amount of complications. Leadless pacemakers (LP) are emerging as an alternative to conventional devices. This article provides a systematic review of patient eligibility, safety and clinical outcomes of the LP devices.
A systematic search for articles describing the use of LP was conducted. Out of two databases, 24 articles were included in the qualitative analysis. These articles comprised a total of 4739 patients, with follow-up times of 1-38 months. Further information was obtained from 10 more studies.
From a population of 4739 patients included in the qualitative analysis, 4670 LP were implanted with success (98.5%). A total of 248 complications were described (5.23%) during the follow-up. The most common were pacing issues such as elevated thresholds, dislodgements or battery failure (68 patients), events at the femoral access site such as hemorrhage, hematoma or pseudoaneurysms (64 patients) and procedure related cardiac injuries such as cardiac perforation, tamponade or pericardial effusion (47 patients). There were 360 deaths during the follow-up and 11 were described as procedure or device related. Four studies presented the strategy of using a combined approach of atrioventricular node ablation (AVNA) and LP implantation.
Leadless pacemakers seem to have a relatively low complication rate. These devices may be a good option in patients with an indication for single-chamber pacing, in patients with conditions precluding conventional transvenous pacemaker implantations. Studies directly comparing LP and transvenous pacemakers and data on longer follow-up periods are needed.

Cystic tumor of the atrioventricular node is an extremely rare primary tumor of the heart. Here we report a case of a 41-year-old female who presented with dizzy and palpitations. Electrocardiography revealed third-degree atrioventricular block. Echocardiography and Chest computed tomography showed a mass attached to the interatrial septum. Intraoperative frozen pathological examination revealed that the mass was the cystic tumor of the atrioventricular node. The diagnosis was proved by histopathology and immunohistochemistry. This is the first case that was diagnosed dependent on frozen pathological examination and treated successfully with surgery.

The beneficial effect of sinus bradycardia during targeted temperature management (TTM) in cardiac arrest patients remains doubtful. We aimed to investigate the impact of sinus bradycardia on survival and neurological outcome. MEDLINE (PubMed), Cochrane, Google Scholar, and ClinicalTrials.gov databases were searched for studies reporting on comatose postcardiac arrest patients presenting sinus bradycardia during TTM. Outcomes were the 180-day survival and final neurologic function assessed by the Cerebral Performance Category scale. The effect size on study outcomes is presented as odds ratio (OR) with 95% confidence interval (CI). Two studies with 681 patients were included. Compared to no-sinus bradycardia group, in patients with sinus bradycardia below 50 bpm, a significant effect of sinus bradycardia on reduction of 180-day mortality was reported (OR = 0.42; 95% CI: 0.29-0.59). No heterogeneity was detected. Sinus bradycardia below 50 bpm during TTM may be protective and should be considered in comatose postcardiac arrest patients.

Two middle-aged female patients presenting with heart palpitation and electrocardiogram revealed complex cardiac arrhythmias. A review of systems was positive for dry mouth and transient arthralgia, while laboratory and instrumental tests enabled us to make the diagnosis of primary Sjögren\'s syndrome (pSS). Cardiac electrophysiology revealed atrioventricular node dysfunction and impaired intraventricular conduction. Prednisone therapy induced a significant improvement in symptoms and electrocardiographic readings. The diagnosis of pSS should be considered in a patient presenting with complex cardiac arrhythmias.