Morphology of right atrial appendage for permanent atrial pacing and risk of iatrogenic perforation of the aorta by active fixation lead

[Lead placement in cardiac implantable electronic devices]

The implantation of electrodes for cardiac implantable electronic devices (CIED) requires profound technical understanding and precise execution. The positioning of electrodes in the right ventricle and atrium has significant implications for patient safety and the effectiveness of CIED therapy. Particular focus is given to the distinction between apical and septal stimulation in ventricular positioning. Based on current data, this article provides a practice-oriented guide that leads implanters through the individual steps of electrode positioning. The implantation of electrodes for physiological stimulation (cardiac resynchronization therapy, CRT, and conduction system pacing, CSP) is not addressed in this article.

Atrial lead perforation early after device implantation-a case report and literature review

We report three patients with screw-in lead perforation in the right atrial free wall not long after device implantation. All the patients complained of intermittent stabbing chest pain associated with deep breathing during the implantation. The "dry" epicardial puncture was utilized to avoid hemopericardium during lead extraction in the first case. The atrial electrode was repositioned in all cases and replaced by a new passive fixation lead in two patients with resolution of the pneumothorax or pericardial effusion. A literature review of 50 reported cases of atrial lead perforation was added to the findings in our case report.

Anatomic, histologic, and mechanical features of the right atrium: implications for leadless atrial pacemaker implantation

BACKGROUND

Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known.

OBJECTIVES

We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human.

METHODS AND RESULTS

Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery.

CONCLUSIONS

Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations.

EHRA expert consensus statement and practical guide on optimal implantation technique for conventional pacemakers and implantable cardioverter-defibrillators: endorsed by the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), and the Latin-American Heart Rhythm Society (LAHRS)

With the global increase in device implantations, there is a growing need to train physicians to implant pacemakers and implantable cardioverter-defibrillators. Although there are international recommendations for device indications and programming, there is no consensus to date regarding implantation technique. This document is founded on a systematic literature search and review, and on consensus from an international task force. It aims to fill the gap by setting standards for device implantation.

Checking the shape and lobation of the right atrial appendage in view of their clinical relevance

Clinically, anatomy of the appendage of the atrium is associated with atrial fibrillation, with the shape and lobation of the appendage having been used to stratify the risk of thromboembolic events. The aim of this study was to examine the age-dependent change in the shape and lobation of the right atrial appendage. A cross-sectional evaluation of the heart of 172 adults and 61 children, fixed in 4% formalin solution was performed. The morphology of the atrial appendage was assessed based on its shape and number of lobes. The following shapes of the appendage were identified: horse head, parrot beak, anvil, sailboat, and undefined. Using the horse head shape as a reference, the risk for a thromboembolic event was higher for anvil, sailboat and undefined shapes of the appendage (p < 0.001). The number of lobes ranged between 1 and 6 in adults, and 1 and 5 in children. The number of lobes for each shape was equivalent between adults and children (p > 0.05). Our analysis indicated that the number of lobes and the distribution of shapes of the atrial appendage remained unchanged throughout life. The risk for a thromboembolic event increased with the morphological complexity of the appendage (anvil, sailboat, and undefined), with 21% of adult hearts being prone to intra-atrial thrombosis in cases of fibrillation.

Morphologic classification of the right auricule on 256-slice computed tomography

PURPOSE

To investigate the shape of right auricule on 256-slice computed tomography (CT).

MATERIALS AND METHODS

Five hundred people (250 men, age range 16-84 years) who had cardiac multidetector CT angiography were recruited in this study. All patients had normal sinus rhythm with normal blood pressure (<140/90 mmHg for systolic/diastolic pressure). The morphology of the right auricule was studied and compared after reconstruction of the raw images.

RESULTS

All patients successfully had cardiac CT angiography (100%), and the right auricule morphology was divided into five types and nine subtypes, including Type I of triangular shape (Ia and Ib), Type II of M shape (IIa and IIb), Type III of L shape (IIIa and IIIb), Type IV of reverse L shape (IVa and IVb), and Type V of balanced shape. The most common type of right auricule is Type IV (28.4%) followed by Type II (24.0%), whereas the least common is Type V (11.0%). Type Ia was present significantly (P < 0.0001) more frequently in females than in males, whereas Type IIa significantly (P = 0.042) more frequently in males than females. No other significant (P > 0.05) sex difference existed in the constitution ratio of the types. The normal angle was greater in Type Ib than in Ia. The greater the normal angle in Type I, the greater the deviation of the right auricule tip towards the left.

CONCLUSION

A good understanding of the right auricule anatomical morphology can better guide atrial pacing, radiofrequency ablation and other surgical procedures while preventing possible intra-procedural complications.