Presentation
Presented post-collapse. A 12-lead ECG revealed 2:1 atrioventricular nodal block and they were referred to cardiology and it was decided to place a permanent pacemaker. The physician performing the procedure noted difficulty in gaining cephalic vein access and therefore a subclavian approach was used. The patient reported slight pleuritic chest pain post-insertion.
Patient Data
The initial post-procedure film shows a small apical left-sided pneumothorax.
A follow-up image one day later shows progression of the pneumothorax and a change in the configuration of the pacemaker lead within the hemithorax. There is associated surgical emphysema and a moderate left-sided pleural effusion. A CT thorax was requested.
The CT findings are consistent with a left-sided pneumothorax, approximately 4 cm in depth. The pacemaker lead enters the thoracic cavity where it loops, prior to re-entering the innominate vein more medially. There is associated left-sided surgical emphysema and moderate density fluid (40 HU) consistent with hemorrhage.
Reformatted CT composite image shows appearance identical to the post-procedure chest x-ray.
A left-sided intercostal chest drain was inserted, which drained air and heavily blood-stained fluid. A follow-up chest x-ray demonstrates significant improvement of the pneumothorax. The configuration of the pacing wire has changed in keeping with re-expansion of the lung.
Images courtesy of Dr H. Mansoubi
Case Discussion
Pneumothorax following pacemaker implantation is a well-recognized complication with an incidence of 0.6-5% reported in case series.
This case is notable for the considerable change in configuration of the pacing lead within the pleural cavity. The CT scan was reviewed with a local thoracic radiologist who raised a suggestion that the pacing lead had exited the brachiocephalic vein, appeared to pierce the visceral pleura, before exiting the lung and re-entering the brachiocephalic vein once more. We presumed that this may have occurred as a result of the more complicated subclavian route. The CT appeared to show that a portion of the apical upper lobe had been ‘snagged’ by the needle and wire. This raised a significant concern that the developing pneumothorax was distorting the pacing wire within the pleural cavity. It was postulated that progression of the pneumothorax may result in further lead displacement and potential loss of pacing, in addition to clinical deterioration due to the pneumothorax itself.
The case was discussed with two regional cardiothoracic centers and all images were reviewed. One center had never encountered such a problem, and were unable to provide advice. The other center also felt it was a very unusual situation however, given that the pneumothorax had resolved post-drain and the patient was well, there was no indication for removing the pacing lead from the lung as it now represented a ‘closed system’. They added that interval imaging was important; if a recurrent pneumothorax was observed this would result in a pleural tear (the pacing lead may result in a ‘cheese-wiring’ effect on the lung) and would necessitate lead extraction with thoracic support.
Over the next couple of days the patient was reviewed clinically and the chest drain was removed once we were satisfied that stable re-expansion had occurred, the patient was discharged home. A follow-up CT thorax one month later showed completely stable appearances with the pacing wire exiting the left subclavian vein above the first rib looping once in the apical pleural space and re-entering the venous system via the lateral side of the left brachiocephalic vein at the medial end of the clavicle.
The patient remains well over two years later with no need for any further intervention. No significant adverse pacing events have been recorded. To our knowledge this phenomenon is not well-described in the literature, however this case may demonstrate that such a complication can be managed conservatively without the need for extensive revision of pacemaker leads.
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