Introduction: Transcatheter radiofrequency ablation has emerged as an important treatment modality for PAF . The risk of thromboembolism, pulmonary vein stenosis, and cardiac perforation has been documented. However, only one case of transient right phrenic nerve injury during pulmonary vein (PV) RF ablation has been reported . We document a case of permanent right phrenic nerve paralysis following PV-RF ablation.
Case Report: A 61-year-old man with a 6-year history of PAF was admitted for PV-RF. His physical examination was unremarkable. An echocardiogram showed normal cardiac chamber size and function and four pulmonary veins. Electrophysiology studies revealed idiopathic AF with multiple pulmonary vein foci. PV-RF ablation was performed as described by Haissaguerre [1,3]. A total of 41 RF pulses for duration of 2080 seconds was required to ablate the arrhythmogenic foci. On post-procedure day one, he complained of dyspnea and orthopnea. A ventilation/perfusion scan was negative for pulmonary thromboembolism. A chest X-ray revealed elevation of the right hemidiaphragm (Figure I). Fluoroscopy confirmed paralysis of the right hemidiaphragm. Pulmonary function tests (PFT) revealed moderate restrictive pulmonary physiology (Table I). On post-procedure day six, his symptoms improved but right hemidiaphragm elevation persisted. Five months later, he was asymptomatic. However, the chest X-ray, fluoroscopy, and PFT revealed persistent right hemidiaphragm paralysis and restrictive pulmonary physiology.
Discussion: Phrenic nerve paresis is an uncommon but potentially disabling complication of PV-RF ablation. Three mechanisms of injury have been implicated: 1. heat from the catheter contact site to the nerve ; 2. injury from the high intensity electromagnetic field generated at the catheter tip ; and 3. generation of a resonance current around the heart . In this patient, the second mechanism seems most likely to induce direct nerve injury secondary to electroporation from locally generated electromagnetic field.
Conclusion: This case report demonstrated that PV-RF ablation can induce significant nerve injury around the heart.
Implication: Careful preventive precautions during the PV-RF ablation procedure are recommended.
PFT on three days and five months post-procedure, showing restrictive physiology.*Three-days post-procedureFive-months post-procedurePredictedObserved%PredictedPredictedObserved%PredictedFVC4.90 L2.53 L52%4.59 L2.72 L59%FEV13.41 L2.22 L65%3.67 L2.27 L62%FEV1/FVC7088126%7983105%TLC7.28 L4.48 L62%6.884.53 L66%*
FVC, forced vital capacity; FEV1, forced expiratory volume-1 second; TLC, total lung
Long Le, None.