Background-Radiofrequency ablation of tissues in pulmonary veins can eliminate paroxysmal atrial fibrillation. Objective-To explore the characteristics of normal pulmonary veins so as to provide more information relevant to radiofrequency ablation. Methods-20 structurally normal heart specimens were examined grossly. Histological sections were made from 65 pulmonary veins. Results-The longest myocardial sleeves were found in the superior veins. The sleeves were thickest at the venoatrial junction in the left superior pulmonary veins. For the superior veins, the sleeves were thickest along the inferior walls and thinnest superiorly. The sleeves were composed mainly of circularly or spirally oriented bundles of myocytes with additional bundles that were longitudinally or obliquely oriented, sometimes forming mesh-like arrangements. Fibrotic changes estimated at between 5% and 70% across three transverse sections were seen in 17 veins that were from individuals aged 30 to 72 years. Conclusions-The myocardial architecture in normal pulmonary veins is highly variable. The complex arrangement, stretch, and increase in fibrosis may produce greater non-uniform anisotropic properties. (Heart 2001;86:265-270) Keywords: arrhythmias; catheter ablation; fibrillation; cardiac veins Studies from various groups of investigators have suggested that certain forms of atrial fibrillation are related to the existence of an ectopic discharging focus which is frequently located within the pulmonary veins.1-4 Radiofrequency catheter ablation carried out in the pulmonary veins can eliminate paroxysmal atrial fibrillation in many cases. Stenosis of the vein is a recognised complication following catheter ablation.5 Recurrence of the arrhythmia is also a common problem.4 Both drawbacks of current techniques of catheter ablation in these patients may be avoidable if there is better understanding of the architecture of the pulmonary veins in the human heart.In this study, we explored the walls of the pulmonary veins from the venoatrial junction to the hilum in normal specimens. We then reconstructed our findings so as to provide a three dimensional impression of the architecture of the cardiac muscle, which reinforces to a varying extent the outer layer of the pulmonary veins at their junction with the left atrium. To standardise the orientation of the left and right pulmonary veins, and to emphasise the potential significance of the diVerences in the anatomical arrangements, we viewed the orifices of the veins as they would be seen in a simulated left anterior oblique projection, and used the clock face to describe the sectors of the walls.
MethodsWe harvested 65 veins from 20 structurally normal heart specimens that were collected in
Background-Esophageal injury is a potential complication after intraoperative or percutaneous transcatheter ablation of the posterior aspect of the left atrium. Understanding the spatial relations between the esophagus and the left atrium is essential to reduce risks. Methods and Results-We examined by gross dissection the course of the esophagus in 15 cadavers. We measured the minimal distance of the esophageal wall to the endocardium of the left atrium with histological studies in 12 specimens.To measure the transmural thickness of the atrial wall, we sectioned another 30 human heart specimens in the sagittal plane at 3 different regions of the left atrium. The esophagus follows a variable course along the posterior aspect of the left atrium; its wall was Ͻ5 mm from the endocardium in 40% of specimens. The posterior left atrial wall has a variable thickness, being thickest adjacent to the coronary sinus and thinnest more superiorly. Behind is a layer of fibrous pericardium and fibrofatty tissue of irregular thickness that contains esophageal arteries of 0.4Ϯ0.2-mm external diameters.
Conclusions-The
The right phrenic nerve is at risk when ablations are carried out in the superior caval vein and the right superior pulmonary vein. The left phrenic nerve is vulnerable during lead implantation into the great cardiac and left obtuse marginal veins.
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