Centennial of the original description of Mobitz type II second-degree atrioventricular block.

The year 2024 marks the centenary of Mobitz's description of type II second-degree atrioventricular block. Its definition remains valid to this day with only minor modification for the diagnosis of infranodal conduction block. Mobitz a century ago indicated that his type II atrioventricular block was associated with Stock-Adams attacks and a prolonged duration of the QRS complex before the eventual description of bundle branch block.

Definitions and Pitfalls in the Diagnosis of Atrioventricular Block.

The widespread use of disparate definitions of atrioventricular block has created important diagnostic problems. Adherence to the correct definitions provides a logical and simple framework for clinical evaluation. This review focuses on the clinical importance of the definitions in the diagnosis of the various types of atrioventricular (AV) block and the associated diagnostic pitfalls.

Problematic definitions of Mobitz type II second degree AV block: Historical aspects.

Problems with the definition of type II second degree AV block are best understood by reviewing the historical aspects that include Mobitz's original description, the contributions of the Chicago Arrhythmia School and the growing importance of excluding slowing of the sinus rhythm.

Transient fetal atrioventricular block: A series of four cases and approach to management.

INTRODUCTION: Fetal atrioventricular block (AVB) is a failure of conduction from atria to ventricles. Immune- and nonimmune-mediated forms occur, especially in association with congenital heart disease. Second-degree (2°) AVB may be reversible with dexamethasone and intravenous immunoglobulin in immune-mediated disease. However, once third-degree AVB develops, it is deemed irreversible with need for a pacemaker and risk for cardiomyopathy. Rarely, 2° AVB is a transient, benign phenomenon in the immature conduction system. Few case series of transient AVB have been reported, but a management approach has not been defined. METHODS/RESULTS/CONCLUSION: We report four patients with self-resolving, nonimmune fetal AVB and outline a management strategy.

Incidental electrocardiogram abnormalities in children undergoing polysomnography.

STUDY OBJECTIVES: Monitoring electrocardiogram is an integral component of pediatric polysomnography (PSG). There are limited data regarding arrhythmia and conduction disturbances in the pediatric population undergoing a PSG. In this work we present abnormal electrocardiogram findings during PSG in our sleep center. METHODS: A retrospective chart review from children who underwent PSG read by a single sleep medicine physician in the last year was carried out. Findings in children without cardiac disease and with first or second degree atrioventricular block were compared to those from children with premature ventricular contractions. RESULTS: A total of 1,235 PSGs were included. Twenty-four children (9 girls and 15 boys) aged 2-17 years (median 9 years) were identified with arrhythmias or conduction disturbances (1.9%). Nineteen out of 24 of these children (79.2%) had obstructive apnea-hypopnea index > 1 event/h; this frequency was not significantly different from that found in the whole group of 1,235 children. No statistically significant difference was found between children with atrioventricular block or premature ventricular contractions. Seven out of 9 children with atrioventricular block and 7 out of 10 with premature ventricular contractions had obstructive apnea-hypopnea index > 1 event/h, while 8 children with atrioventricular block out of 9 and 4 out of 10 with premature ventricular contractions were males (Fisher's exact test P = .04). None of the children were found to have a structural or conduction abnormality when referred to cardiology. CONCLUSIONS: Our study supports that electrocardiogram abnormalities are rare in PSGs of children and not associated with cardiac disease or sleep disorders but appear more commonly in males. CITATION: Amin A, Mogavero MP, Ferri R, DelRosso LM. Incidental electrocardiogram abnormalities in children undergoing polysomnography. J Clin Sleep Med. 2021;17(12):2393-2398.

A retrospective evaluation of the indications, complications, and outcomes associated with epicardial pacemakers in 20 cats from a single institution.

INTRODUCTION: The objective of this retrospective study was to describe the indications, complications, and long-term outcomes in a group of cats that received an epicardial pacing (EP) system. ANIMALS: Twenty client-owned cats. MATERIALS AND METHODS: Medical records were reviewed for signalment, presenting complaint, primary electrocardiogram (ECG) diagnosis, presence of structural heart disease, presence of congestive heart failure (CHF), presence of major or minor complications, and survival time. RESULTS: The majority of cats were presented for syncope (n = 11), and the most common ECG diagnosis was advanced second-degree atrioventricular block (n = 9). Fifteen cats (15/20, 75%) had one or more major or minor complications. One cat died in the perioperative period as a result of a major complication. None of the variables evaluated were associated with a statistically significant increase in the occurrence of major or minor complications. The most common major complication was loss of ventricular capture (seven instances in six cats), which was successfully treated in all cases by increasing pacemaker output or replacing both the lead and the pulse generator. The most common minor complications were arrhythmias (n = 7) and sensing issues (n = 8). The overall median survival time (MST) was 948 days. No statistical difference in survival time was identified between cats that experienced a major complication and those that did not. CONCLUSIONS: Although complications were common in this feline population after EP, major and minor complications were successfully treated.

Meningitis and high-grade, second-degree atrioventricular block in an adolescent: causal effect or coincidence?

We describe an adolescent with Streptococcus pneumoniae meningitis and symptomatic high-grade, second-degree atrioventricular block requiring permanent pacemaker placement. It is difficult to ascertain if these two diagnoses were independent or had a causal relationship though ongoing symptoms were not present prior to the infection. Because of this uncertainty, awareness that rhythm disturbances can be cardiac in origin but also secondary to other aetiologies, such as infection, is warranted.

Dynamic Electrocardiography is Useful in the Diagnosis of Persistent Atrial Fibrillation Accompanied with Second-Degree Atrioventricular Block.

BACKGROUND: Periodic electrocardiography (ECG) at every clinical visit is generally performed for heart rhythm surveillance, and 24-h Holter ECG is usually used as the gold standard. We aimed to investigate the electrocardiographic features of persistent atrial fibrillation (AF) accompanied with second-degree atrioventricular block (AVB). METHODS: From October 2012 to November 2015, 204 patients with an RR interval > 2.0 s before radiofrequency ablation were included. Dynamic ECG (DCG) was performed before and after the radiofrequency ablation. The patients were divided into two groups based on changes in DCG after radiofrequency ablation: group A (non-second-degree AVB group) and group B (second-degree AVB group). An RR interval > 2.0 s, the distribution of escape rhythm, mean heart rate and the long RR interval in the two groups were analyzed. RESULTS: After radiofrequency ablation, all 204 patients who had persistent AF converted to sinus rhythm successfully. In group A (n = 193), the distribution of an RR interval > 2.0 s and escape rhythm were significantly correlated with sleep or rest, while no correlation was observed in group B (n = 11). The average RR interval prolongation and escape rhythm were significantly higher in group B than in group A (p < 0.05). The average number of long RR intervals > 3.0 s and average number of escape rhythm episodes (< 35 bpm) were significant predictive factors of second-degree AVB after radiofrequency ablation. CONCLUSIONS: DCG is a useful tool for the diagnosis of persistent AF accompanied with second-degree AVB.

Computed tomography is important in appropriately diagnosing patients with third-degree atrioventricular block and second-degree atrioventricular block but not Wenckebach type.

PURPOSE: To evaluate CT utility for detection of cardiac or lung abnormalities in the diagnosis of organic cardiac disease in subjects with second- or third-degree atrioventricular block (AVB) excepting Wenckebach type. MATERIALS AND METHODS: A total of 50 consecutive patients (25 male; 64±15years) with de novo third- or second-degree AVB underwent both TTE and a combination of cardiac and chest 320 slice CT (Aquilion one, Toshiba Medical) and were retrospectively analyzed. The presence of focal left ventricular (LV) wall thinning and thickening was evaluated on both TTE and cardiac CT. We evaluated the presence of significant coronary artery stenosis, focal late enhancement (LE) in LV myocardium, significant-sized (>10mm) lymph nodes in hialus or mediastinum and/or typical lung nodules for sarcoidosis on CT. RESULTS: Abnormalities for 26%, 30%, and 36% of patients were demonstrated on TTE, cardiac CT, and a combination of cardiac and chest CT, respectively. 12% and 18% patients who did not exhibit cardiac abnormalities on TTE, revealed abnormalities on cardiac CT, or a combination of cardiac and chest CT, respectively. 36% patients had organic cardiac diseases. Sensitivities for detection of organic cardiac disease were significantly greater when cardiac and chest CT were combined than TTE alone (P<0.01). CONCLUSIONS: Approximately one third of patients with third- or second-degree AVB had organic cardiac diseases. For detection of cardiac and chest abnormality and correct diagnosis of organic cardiac disease in patients with third- or second-degree AVB, TTE is not sufficient on its own. CT or a combination of TTE and CT are required.

Second-Degree Atrioventricular Block Occurring After Tooth Extraction.

Although cardiac arrhythmias are occasionally associated with dental extractions and dental anesthesia, atrioventricular block is rarely seen during dental procedures. We report a rare case of type I second-degree atrioventricular block (Wenckebach phenomenon) occurring after bilateral extraction of impacted mandibular third molars under general anesthesia in a 16-year-old Japanese girl. Under consultation with a cardiovascular physician, we carefully monitored the patient's vital signs postoperatively, including blood pressure, oxygen saturation, and electrocardiogram, using a bedside monitor. Her postoperative course was uneventful. A 12-lead electrocardiogram the following day revealed no abnormality. In this case, we hypothesize that extubation of the nasotracheal tube or oral/pharyngeal suction might have triggered a vagal reflex that caused type I second-degree atrioventricular block. Our experience indicates that standard cardiovascular monitoring should be used for patients undergoing dental treatment under general anesthesia, even for young, healthy patients, to prevent and detect cardiovascular emergencies.

Pacemaker dependency after transcatheter aortic valve implantation with the self-expanding Medtronic CoreValve System.

BACKGROUND/OBJECTIVES: To determine pacemaker (PM) dependency at follow-up visit in patients who underwent new permanent pacemaker implantation (PPI) following transcatheter aortic valve implantation (TAVI). METHODS: Single center prospective observational study including 167 patients without previous PM implantation who underwent TAVI with the self-expanding Medtronic CoreValve System (MCS) between November 2005 and February 2011. PM dependency was defined by the presence of a high degree atrioventricular block (HDAVB; second [AV2] and third degree [AV3B]), or a slow (<30 bpm) or absent ventricular escape rhythm during follow-up PM interrogation. RESULTS: A total of 36 patients (21.6%) received a new PM following TAVI. The indication for PM was AV2B (n=2, 5.6%), AV3B (n=28, 77.8%), postoperative symptomatic bradycardia (n=3, 8.3%), brady-tachy syndrome (n=1, 2.8%), atrial fibrilation with slow response (n=1, 2.8%) and left bundle branch block (n=1, 2.8%). Long term follow-up was complete for all patients and ranged from 1 to 40 months (median (IQR): 11.5 (5.0-18.0 months). Of those patients with a HDAVB, 16 out of the 30 patients (53.3%) were PM independent at follow-up visit (complete or partial resolution of the AV conduction abnormality). Overall, 20 out of the 36 patients (55.6%) who received a new PM following TAVI were PM independent at follow-up. CONCLUSION: Partial and even complete resolution of peri-operative AV conduction abnormalities after MCS valve implantation occurred in more than half of the patients.

Observation on integrated differentiantion of disease and TCM syndrome for treaing 35 cases of second degree atrioventricular block / 中华中医药杂志

Objective:To observe the clinical effects of integrated disease and TCM syndrome on patients with second degree atrioventricular block.Methods:Because of the lentor cardiac rhythm characteristics of econd degree atrioventricular block,the herbs which had the effect in increasing cardiac rhythm were selected and were used in combination of clinical syndrome differentiation to treat 35 cases of second degree atrioventricular block.Results:The total effective rate was 88.6%.Conclusion:Integrated differentiation of disease and TCM syndrome had significant effects on second degree atrioventricular block.