How close are the phrenic nerves to cardiac structures? Implications for cardiac interventionalists.
BACKGROUND
Phrenic nerve injury is a recognized complication following cardiac intervention or surgery. With increasing use of transcatheter procedures to treat drug-refractory arrhythmias, clarification of the spatial relationships between the phrenic nerves and important cardiac structures is essential to reduce risks.


RESULTS
We examined by gross dissection the courses of the right and left phrenic nerves in 19 cadavers. Measurements were made of the minimal and maximal distances of the nerves to the superior caval vein, superior cavoatrial junction, right pulmonary veins, and coronary veins. Histologic studies were carried out on tissues from six cavaders. Tracing the course of the right phrenic nerve revealed its close proximity to the superior caval vein (minimum 0.3 +/- 0.5 mm) and the right superior pulmonary vein (minimum 2.1 +/- 0.4 mm). The anterior wall of the right superior pulmonary vein was <2 mm from the right phrenic nerve in 32% of specimens. The left phrenic nerve passed over the obtuse cardiac margin and the left obtuse marginal vein and artery in 79% of specimens. In the remaining specimens, its course was anterosuperior, passing over the main stem of the left coronary artery or the anterior descending artery and great cardiac vein.


CONCLUSIONS
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.
Sánchez-Quintana
Damian
D
Department of Human Anatomy, Faculty of Medicine, University of Extremadura, Badajoz, Spain.
Cabrera
José Angel
JA
Climent
Vicente
V
Farré
Jerónimo
J
Weiglein
Andreas
A
Ho
Siew Yen
SY
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D003331:Coronary Vessels / Q000033:anatomy & histology*; D004210:Dissection; D005260:Female; D006321:Heart / Q000033:anatomy & histology; D006325:Heart Atria / Q000033:anatomy & histology; D006329:Heart Conduction System / Q000033:anatomy & histology; D006352:Heart Ventricles / Q000033:anatomy & histology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010791:Phrenic Nerve / Q000033:anatomy & histology* / Q000293:injuries; D011667:Pulmonary Veins / Q000033:anatomy & histology* / Q000601:surgery; D014683:Vena Cava, Superior / Q000033:anatomy & histology* / Q000601:surgery