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Successful removal of a circular mapping catheter which perforated the pulmonary vein during cryoballoon ablation by lateral thoracotomy: a case report

Abstract Background Serious complications may occur during cryoballoon ablation (CBA). However, pulmonary vein (PV) perforation by a circular mapping catheter and the strategy for removing the catheter remain poorly understood. Case summary A 40-year-old male presented with palpitations 2 years ago and was diagnosed with paroxysmal atrial fibrillation 5 months ago. He underwent CBA for paroxysmal atrial fibrillation. After isolation of the left PV, a circular mapping catheter was advanced in the right inferior pulmonary vein (RIPV), and single freeze was performed. After isolation of the PV, the catheter tip was immobile and could not be withdrawn with significant resistance. Computed tomography showed that the catheter tip perforated the posterior basal vein (V10) of the RIPV and remained in the right lower lobe, along with intrapulmonary haemorrhage. The patient underwent surgery via right lateral thoracotomy to remove the catheter. The RIPV was peeled to the periphery to expose the V10. The catheter perforated the vessel wall in the middle of the V10 and entered the pulmonary parenchyma. A microincision on the lung parenchyma covering the surface of the catheter tip was performed, and the circular distal portion of the catheter was cut. The entire catheter (i.e. shaft and proximal portion) was successfully removed from the transseptal catheter. Discussion Surgical approach was performed for the management of PV perforation caused by a circular mapping catheter. This case may assist in troubleshooting and problem-solving in case such an event occurs again during procedures in the future.


Introduction
Cryoballoon ablation (CBA) has been widely accepted as a treatment of paroxysmal atrial fibrillation. 1 It is established that serious complications (i.e. oesophageal ulcer, atrial oesophageal fistula, bronchial injury, and phrenic nerve injury) occur during CBA. 2 However, pulmonary vein (PV) perforation by a circular mapping catheter and the strategy for removing the catheter remain poorly understood. Herein, we describe the first application of lateral thoracotomy for the removal of a circular mapping catheter which perforated the PV during CBA.

Case presentation
A 40-year-old man presented with palpitations 2 years ago and was diagnosed with paroxysmal atrial fibrillation 5 months ago. He was receiving anticoagulation treatment with edoxaban.
On admission, the examinations showed that he was haemodynamically stable. Surface 12-lead electrocardiography revealed sinus rhythm. Laboratory investigations revealed no notable findings. Physical examination, chest X-ray, and echocardiography did not yield evidence of clinically overt structural and/or organic heart disease.
Catheter ablation using the CBA system was performed under sedation with dexmedetomidine. A transseptal puncture was performed without any complication, and angiography of the left atrium (LA) showed four independent PVs. Heparin was administered to maintain an activated clotting time >300 s. A 20-mm circular mapping catheter (Achieve TM ; Medtronic, Minneapolis, MN, USA) and a 28mm cryoballoon catheter (Arctic Front TM ; Medtronic) were advanced into the LA via a steerable sheath. Firstly, we targeted the two left PVs with single freeze, under observation of the oesophageal temperature using an internal oesophageal probe. Afterwards, a circular mapping catheter was advanced in the right inferior pulmonary vein (RIPV), and single freeze was performed along with phrenic nerve capture ( Figure 1A). After isolation of the PV, an attempt was made to withdraw the catheter from the PV. However, the catheter tip was immobile and could not be withdrawn with significant resistance. Repeated attempts to withdraw the catheter by rotational traction were not effective ( Figure 1B). Computed tomography showed that the catheter tip perforated the posterior basal vein (V10: posterior basal vein) of the RIPV and was stuck in the right lower lobe, along with intrapulmonary haemorrhage (Figure 2A and B). Considering that strong traction could cause major bleeding and breakage of the catheter, surgical removal was performed after obtaining informed consent from the patient.
Surgery was performed via right 7th intercostal lateral thoracotomy. The right lung (mainly S10: posterior basal segment) was congested due to intrapulmonary haemorrhage. The RIPV was peeled to the periphery to expose the posterior basal vein (V10). The catheter perforated the vessel wall in the middle of V10 and entered the pulmonary parenchyma ( Figure 3A). The catheter could not be removed even through direct traction. A microincision on the lung parenchyma covering the surface of the catheter tip was performed, and the circular distal portion of the catheter was cut ( Figure 3B). The entire catheter (i.e. shaft and proximal portion) was successfully removed from the transseptal catheter, and the V10 was repaired using suture. The removed catheter had a fracture at the junction of the distal portion and the shaft due to repeated traction ( Figure 4). After surgery, the patient had an uneventful course without evidence of complications.

Discussion
To the best of our knowledge, this is the first reported application of a surgical approach for the removal of a circular mapping catheter which perforated the PV during CBA.
Firstly, perforation of the PV by a circular mapping catheter during CBA is a very rare complication. The incidence of this complication is unknown, and only a few cases of circular mapping catheter entrapment or perforation of the PV have been reported. [3][4][5][6] This complication may be caused by the distal portion (tip) of the catheter becoming lodged in a small side branch or diverticulum. 3 Currently, there is no practical approach described in the literature for managing this situation. In a previous case, the catheter was successfully removed by traction, and conservative treatment of pulmonary haemorrhage was possible. 5 However, this manoeuvre is associated with a risk of a major haemorrhage. It has also been reported that the catheter may fracture at the junction of the distal portion (soft and pliable) and the shaft (stiff), and at the tip between the straight and circular parts due to repeated traction. 3,4,6 In this case, a circular mapping catheter perforated a small branch of the PV and remained in the lung parenchyma. Thus, the surgical approach was selected as a safe method for the removal of the catheter to avoid the risk of fracture of the catheter, and the occurrence of a fatal bleeding event requiring an emergency thoracotomy.
Secondly, lateral thoracotomy was performed to remove the catheter which perforated the PV. In a previous case, it was reported that an ablation catheter, which perforated near the ostium of the RIPV, was removed by open-heart surgery. 7 this previous case, in the present case, perforation occurred on the distal side of the RIPV. Therefore, it was considered difficult to reach the perforated site through the LA. Surgery via lateral thoracotomy was selected as the safest and most suitable approach for the removal of the catheter. This method allows the capability of responding to major bleeding after catheter removal and avoids the risk of developing arrhythmias (i.e. atrial fibrillation, atrial flutter, and atrial tachycardia) associated with open heart incision or additional surgery (i.e. Maze procedure and left appendage exclusion). [8][9][10][11][12] In conclusion, lateral thoracotomy was performed for the removal of a circular mapping catheter which caused PV perforation. This case may assist in troubleshooting and problem-solving in case such an event occurs again during procedures in the future.