Clarifying the anatomy of the atrioventricular node artery

3D models of the cardiac conduction system in healthy neonatal human hearts

Iatrogenic damage to the cardiac conduction system (CCS) remains a significant risk during congenital heart surgery. Current surgical best practice involves using superficial anatomical landmarks to locate and avoid damaging the CCS. Prior work indicates inherent variability in the anatomy of the CCS and supporting tissues. This study introduces high-resolution, 3D models of the CCS in normal pediatric human hearts to evaluate variability in the nodes and surrounding structures. Human pediatric hearts were obtained with an average donor age of 2.7 days. A pipeline was developed to excise, section, stain, and image atrioventricular (AVN) and sinus nodal (SN) tissue regions. A convolutional neural network was trained to enable precise multi-class segmentation of whole-slide images, which were subsequently used to generate high- resolution 3D tissue models. Nodal tissue region models were created. All models (10 AVN, 8 SN) contain tissue composition of neural tissue, vasculature, and nodal tissues at micrometer resolution. We describe novel nodal anatomical variations. We found that the depth of the His bundle in females was on average 304 μm shallower than those of male patients. These models provide surgeons with insight into the heterogeneity of the nodal regions and the intricate relationships between the CCS and surrounding structures.

Transient block during radiofrequency ablation well away from the His-Purkinje system: atrioventricular nodal artery trauma?

Cardiac arrhythmias occur at all ages. Cardiac mapping and ablation are established methods for curing arrhythmia substrates; however, complications may occur. We report a patient with transient Wenckebach heart block during radiofrequency ablation in the setting of Wolff Parkinson White syndrome despite the ablation catheter being well away from the atrioventricular node, and we speculate on the potential mechanism.

The anatomy of the atrioventricular nodal artery: A meta-analysis with implications for cardiothoracic surgery and ablation procedures

The objective of the present meta-analysis was to evaluate recent and applicable data regarding the location and variation of the atrioventricular nodal artery (AVNA) in relation to adjacent structures. In order to minimize postoperative risks and maintain physiological anastomosis for proper cardiac function, understanding such possible variations of vascularization of the AV node is of immense importance prior to cardiothoracic surgery as well as ablations. In order to perform this meta-analysis, a systematic search was conducted in which all articles regarding, or at least mentioning, the anatomy of the AVNA was searched. In general, the results were based on 3919 patients. AVNA was found to originate only from the RCA in 82.41% (95% CI: 79.46%-85.18%). The pooled prevalence of AVNA originating only from LCA was found to be 15.25% (95% CI: 12.71%-17.97%). The mean length of AVNA was found to be 22.64 mm (SE = 1.60). The mean maximal diameter of AVNA at its origin was found to be 1.40 mm (SE = 0.14). In conclusion, we believe that this is the most accurate and up-to-date study regarding the highly variable anatomy of the AVNA. The AVNA was found to originate most commonly from the RCA (82.41%). Furthermore, the AVNA was found to most commonly have no (52.46%) or only one branch (33.74%). It is hoped that the results of the present meta-analysis will be helpful for physicians performing cardiothoracic or ablation procedures.

Iatrogenic Atrioventricular Block

Iatrogenic atrioventricular (AV) block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures. In cardiac surgery, patients undergoing aortic and/or mitral valve surgery are at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation. Similarly, patients undergoing transcatheter aortic valve replacement are also at increased risk for developing AV block. Electrophysiologic procedures, including catheter ablation of AV nodal re-entrant tachycardia, septal accessory pathways, para-Hisian atrial tachycardia, or premature ventricular complexes, are also associated with risk of AV conduction system injury. In this article, we summarize the common causes for iatrogenic AV block, predictors for AV block, and general management considerations.

Atrial approaches in mitral valve surgery: a propensity analysis of differences in the incidence of clinically relevant adverse effects

BACKGROUND

The lack of evidence on complications using mitral valve approaches leaves the choice of risk exposure to the surgeon's preference, based on individual experience, speed, ease, and quality of exposure.

METHODS

The present study analysed patients undergoing mitral valve surgery using a superior transseptal approach or a left-atrial approach between 2006 and 2018. We included first-time elective mitral valve procedures, isolated, or combined, without a history of rhythm disturbances. We used propensity score matching based on 26 perioperative variables. The primary endpoint was the association between the superior transeptal approach and clinically significant adverse outcomes, including arrhythmias, need for a permanent pacemaker, cerebrovascular events, and mortality.

RESULTS

A total of 652 patients met the inclusion criteria; 391 received the left atrial approach, and 261 received the superior transseptal approach. After matching, 96 patients were compared with 69 patients, respectively. The distribution of the preoperative and perioperative variables was similar. There was no difference in the incidence of supraventricular tachyarrhythmias or the need for treatment. The incidence of nodal rhythm (p = 0.008) and length of stay in intensive care (p = 0.04) were higher in the superior transseptal group, but the need for permanent pacemaker implantation was the same. Likewise, there was no difference in the need for anticoagulation due to arrhythmia, the incidence of cerebrovascular events or mortality in the postoperative period or in the long-term follow-up.

CONCLUSION

We did not find an association with permanent heart rhythm disorders or any other significant adverse clinical outcome. Therefore, the superior transeptal approach is useful and safe for mitral valve exposure.

Risk factors of pacing dependence and cardiac dysfunction in patients with permanent pacemaker implantation

AIMS

Right ventricular pacing (RVP) dependence could impair left ventricular ejection fraction (LVEF). This study aimed to illuminate the relationship between RVP proportion and LVEF, as well as disclosing independent predictors of RVP dependence.

METHODS AND RESULTS

Patients indicated for permanent pacemaker implantation were included (2016-2020). The ventricular pacing lead was placed in right ventricular apex or septum. Pacing mode programming followed universal standard. Electrocardiographic, echocardiographic, and serological parameters were collected. RVP dependence was defined according to its influence on LVEF. This study was of case-control design. Included patients were matched by potentially confounding factors through propensity score matching. A total of 1183 patients were included, and the mean duration of follow-up was 24 months. Percentage of RVP < 80% hardly influenced LVEF; however, LVEF tended to decrease with higher RVP proportion. High degree/complete atrioventricular block (AVB) [odds ratio (OR) = 5.71, 95% confidence interval (CI): 3.66-8.85], atrial fibrillation (AF) (OR = 2.04, 95% CI: 1.47-2.82), percutaneous coronary intervention (PCI) (OR = 2.89, 95% CI: 1.24-6.76), maximum heart rate (HR_max ) < 110 b.p.m. (OR = 2.74, 95% CI: 1.58-4.76), QRS duration > 120 ms (OR = 2.46, 95% CI: 1.42-4.27), QTc interval > 470 ms (OR = 2.01, 95% CI: 1.33-3.05), and pulmonary artery systolic pressure (PASP) > 40 mmHg (OR = 1.93, 95% CI: 1.46-2.56) were proved to predict RVP dependence.

CONCLUSIONS

High RVP percentage (>80%) indicating RVP dependence significantly correlates with poor prognosis of cardiac function. High degree/complete AVB, AF, ischaemic aetiology, PCI history, HR_max  < 110 b.p.m., QRS duration > 120 ms, QTc interval > 470 ms, and PASP > 40 mmHg were verified as independent risk factors of RVP dependence.

Right Atrium to Left Ventricle Puncture for VT Ablation in Patients with Mechanical Aortic and Mitral Valves: a Step-by-Step Approach

In patients with mechanical valves in the aortic and mitral positions, percutaneous access to the left ventricle (LV) for catheter ablation (CA) of ventricular tachycardia (VT) is challenging. We have recently described a novel percutaneous trans-right atrial (RA) access to the LV via a femoral venous approach for CA of VT in patients with mechanical aortic and mitral valves. With this approach, an iatrogenic Gerbode-type of ventricular septal defect is created with direct puncture of the inferior and medial aspect of the RA anatomically adjacent to the inferior-septal LV. The technique involves the use of steerable sheaths, dedicated radiofrequency (RF) wires, and intracardiac echocardiography (ICE) guidance. The procedure has been documented feasible and safe in a series of consecutive patients with aortic and mitral mechanical valves and VT related to LV substrate. In this article, the procedural details of this novel approach are described in a step-by-step fashion. This article is protected by copyright. All rights reserved.

Iatrogenic Atrioventricular Block

Iatrogenic atrioventricular (AV) block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures. In cardiac surgery, patients undergoing aortic and/or mitral valve surgery are at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation. Similarly, patients undergoing transcatheter aortic valve replacement are also at increased risk for developing AV block. Electrophysiologic procedures, including catheter ablation of AV nodal re-entrant tachycardia, septal accessory pathways, para-Hisian atrial tachycardia, or premature ventricular complexes, are also associated with risk of AV conduction system injury. In this article, we summarize the common causes for iatrogenic AV block, predictors for AV block, and general management considerations.

Severe myocardial bridge presenting as paroxysmal atrioventricular block

Chest pain complicated with electrocardiographic changes is not an uncommon scenario in emergency departments, which should be examined cautiously. We describe a 51-years-old man with a myocardial bridge of coronary artery presenting with simultaneous Mobitz type I atrioventricular block on electrocardiography. Echocardiography excluded valvular abnormality and systolic/diastolic dysfunction. Coronary angiography confirmed the diagnosis of a myocardial bridge at the middle segment of the left anterior descending artery, involving the most dominant septal perforator branch with marked systolic compression. The patient underwent coronary artery bypass grafting surgery and was followed up uneventfully at the outpatient department with medical treatment of diltiazem and clopidogrel. The present case is being reported to highlight that clinicians should be alert to such a congenital abnormality as a potential cause of repeated myocardial infarction and conduction abnormality.

First in situ 3D visualization of the human cardiac conduction system and its transformation associated with heart contour and inclination

Current advanced imaging modalities with applied tracing and processing techniques provide excellent visualization of almost all human internal structures in situ; however, the actual 3D internal arrangement of the human cardiac conduction system (CCS) is still unknown. This study is the first to document the successful 3D visualization of the CCS from the sinus node to the bundle branches within the human body, based on our specialized physical micro-dissection and its CT imaging. The 3D CCS transformation by cardiac inclination changes from the standing to the lying position is also provided. Both actual dissection and its CT image-based simulation identified that when the cardiac inclination changed from standing to lying, the sinus node shifted from the dorso-superior to the right outer position and the atrioventricular conduction axis changed from a vertical to a leftward horizontal position. In situ localization of the human CCS provides accurate anatomical localization with morphometric data, and it indicates the useful correlation between heart inclination and CCS rotation axes for predicting the variable and invisible human CCS in the living body. Advances in future imaging modalities and methodology are essential for further accurate in situ 3D CCS visualization.

Outcomes of Percutaneous Trans-Right Atrial Access to the Left Ventricle for Catheter Ablation of Ventricular Tachycardia in Patients With Mechanical Aortic and Mitral Valves

Importance

In patients with mechanical valves in the aortic and mitral positions, percutaneous access to the left ventricle (LV) via a transfemoral approach for catheter ablation of ventricular tachycardia (VT) has been considered infeasible.

Objective

To describe the outcomes of a novel percutaneous trans-right atrial (RA) access to the LV via a femoral venous approach for catheter ablation of VT in patients with mechanical aortic and mitral valves.

Design, Setting, and Participants

This observational study included consecutive patients with mechanical valves in the aortic and mitral positions and recurrent monomorphic drug-refractory VT associated with an LV substrate. Percutaneous LV access was performed from a transfemoral venous route with the aid of a deflectable sheath and a radiofrequency wire by creating an iatrogenic Gerbode defect with direct puncture of the inferior and medial aspect of the RA, adjacent to the inferior-septal process of the LV (ISP-LV), under intracardiac echography guidance. Once the wire crossed to the LV, balloon dilatation of the ventriculotomy site (with a noncompliant balloon; diameter, 8 to 10 mm) was performed to facilitate passage of the sheath within the LV.

Exposures

Percutaneous trans-RA access to the LV via puncture of the ISP-LV to perform catheter ablation of VT in patients with mechanical aortic and mitral valves.

Main Outcomes and Measures

Feasibility and safety of a trans-RA access to the LV for catheter ablation of VT.

Results

A total of 4 patients (mean [SD] age, 60 [7] years; mean [SD] LV ejection fraction, 31% [9%]) with recurrent VT associated with an LV substrate (ischemic cardiomyopathy, 3 patients; nonischemic cardiomyopathy, 1 patient) and mechanical valves in the aortic and mitral position underwent trans-RA access through the ISP-LV for catheter ablation of VT. The time to obtain LV access ranged from 60 minutes (first case) to 22 minutes (last case) (mean [SD], 36 [15] minutes). No complications associated with the access occurred. In particular, in the 3 patients with preserved atrioventricular conduction at baseline, no new conduction abnormalities were observed after the access. Complete VT noninducibility at programmed ventricular stimulation was achieved in 3 cases, and no patient had VT recurrence at a median follow-up of 14 months (range, 6-21 months).

Conclusions and Relevance

A percutaneous trans-RA access to the LV via a femoral venous approach for catheter ablation of VT in patients with mechanical aortic and mitral valves is feasible and appears safe. This novel technique may allow for catheter ablation of VT in a population of patients in whom conventional LV access via retrograde aortic or atrial transseptal routes is not possible.

Cardiogenic shock due to predominantly right ventricular failure complicating acute myocardial infarction

AIMS

The objective was to describe patient characteristics, interventions, and outcome in acute myocardial infarction complicated by cardiogenic shock (AMICS), due to predominantly right ventricular (RV) failure after revascularization, in comparison with patients suffering from left ventricular (LV) failure as these patients remain sparsely characterized.

METHODS AND RESULTS

From 2010 to 2017, consecutive AMICS patients admitted to either of two tertiary heart centres, covering 3.9 million citizens, corresponding to two-thirds of the Danish population, were identified and individually reviewed through patient records. A total of 1716 AMICS patients were identified, of which 1482 underwent acute revascularization and included for analysis. Hereof, 101 (7%) patients developed cardiogenic shock due to predominantly RV failure, while 1381 (93%) had significant LV involvement. Female sex was the only demographic factor associated with RV failure (35% vs. 25%, P = 0.01). Despite having a preserved LV ejection fraction, patients with predominantly RV failure were comparable to patients with LV involvement, in terms of haemodynamic and metabolic profile, here among variables commonly used in the cardiogenic shock definition including blood pressure (82 mmHg vs. 83 mmHg, P = 0.90) and lactate level (5.7 mmol/L vs. 5.4 mmol/L, P = 0.70). Patients with RV AMICS had significantly lower 30-day mortality than LV AMICS, and this result persisted after multivariable adjustment (RV vs. LV; hazard ratio 0.61, 95% confidence interval 0.41-0.92, P = 0.01).

CONCLUSION

In contemporary AMICS patients undergoing revascularization, patients with predominantly RV failure had comparable haemodynamics and metabolic derangement on admission compared to patients with LV failure but was associated with female sex and a significantly lower 30-day mortality.

Data on the origin, course and distribution of the artery to the human atrioventricular node

This article presents data on the anatomical variation of the origin, course and distribution of the artery to the atrioventricular node in humans. The findings hold clinical significance for coronary intervention, coronary angiography and cardiac pathology in cases of sudden cardiac death. For further interpretation and discussion, the original research article ‘Clarifying the anatomy of the atrioventricular node artery’ by Kawashima and Sato (2018) can be referred [1].