First in World Implant of Atrial Leadless Pacemaker

Mitchell AJ, Walsh KP


Not only is bradyarrhythmia common following atrial redirection procedures for transposition of the great arteries  [1] but treatment is challenging due to a high incidence of lead-related complications in the venous baffles with conventional pacing [2]. Whilst leadless technology offers a single chamber solution and has been described in the sub-pulmonary ventricle in these patients [3], ventricular pacing reduces function of the systemic RV [4] and although tested in animal models [5], a dedicated leadless atrial device for isolated sinus node disease is not yet available. We describe the successful implantation of the ventricular leadless micraTM (Medtronic, USA) pacemaker in the left atrial appendage of two patients previously treated with Mustard repair.

Case 1

47 year-old male with previous Mustard repair and sinus node disease and previous venous baffle stenting. He presented with a syncopal event on a background of increasing exertional dyspnoea and presyncope. A resting ECG demonstrated sinus bradycardia with a ventricular rate of 44/min and right bundle branch block. Systemic right ventricular ejection fraction was 35%. Ambulatory monitoring revealed a flat heart rate profile and nocturnal pauses up to three seconds but no high degree AV block.

Case 2

49 year-old male with previous Mustard repair and previous trans-venous dual chamber pacing for sick sinus syndrome with resultant superior vena caval occlusion. There was intermittent failure to capture on the atrial lead and he was pacing dependent due to Amiodarone therapy for difficult to control atrial arrhythmias. Systemic right ventricular ejection fraction was 45%.


Both cases were performed under general anaesthetic. Venous access was obtained from the left femoral vein and a 24Fr DrysheathTM (Gore, USA) was inserted. A selective injection of the LAA was performed using a pigtail catheter (See figures). Following this, pace mapping of various locations in the appendage was performed to exclude phrenic nerve capture. A Micra TM (Medtronic, USA) device was then implanted using the integrated delivery catheter (See figures).

In case 1 acceptable parameters were achieved on first deployment (DETAILS), multiple recaptures were required in case 2 due to high thresholds but ultimately good pacing parameters were achieved (DETAILS). Stability was tested using standard manoeuvres.  An echo after several hours excluded a pericardial effusion and chest X-ray and pacing check the next day confirmed device position and stable pacing parameters respectively. The patient was discharged the day following the procedure. Clinical follow-up at 6 weeks has again shown excellent pacing parameters in both patients.


This is to our knowledge the first described case of a leadless pacemaker implant in the atrium. The anatomy of atrial redirection patients whilst posing challenges for conventional trans-venous pacing lends itself to leadless atrial pacing. The left atrial appendage is  morphologically better suited to MicraTM implantation than the right given that it is generally longer, has a narrower neck and is more trabeculated (4). This, coupled with the fact that it is readily accessed from the femoral vein makes leadless left atrial appendage pacing a feasible and attractive solution for atrial switch patients who have sinus node disease in whom both trans-venous and ventricular pacing are problematic.


  1. Cuypers JA, Eindhoven JA, Slager M, Opic P, Roos-Hesselink J. et al. ‘The natural and unnatural history of the Mustard procedure: long-term outcome up to 40 years’ European Heart Journal. (2014)35: 1666–74.
  2. Bottega C, Silversides CK, Oechslin EN, Dissanayake K, Harris L et al. ‘Stenosis of the superior limb of the systemic venous baffle following a Mustard procedure: an under-recognized problem’ International Journal of Cardiology (2012) 154(1): 32-7.
  3. Kotschet E, Alasti M, Alison J ‘Micra implantation in a patient with transposition of great arteries’ Pacing and clinical electrophysiology (2019)42(2): 117-9.
  4. Yeo WT, Jarman JW , Li W , Gatsoulis MA, Wong T. Adverse impact of chronic subpulmonary left ventricular pacing on systemic right ventricular function in patients with congenitally corrected transposition of the great arteries. International Journal of Cardiology. Int J Cardiol (2014); 171(2) 184-91
  5. Barbero U, Ho SY. ‘Anatomy of the atria’ Herzschr Elektrophys (2017)28(4):347–54.

Atrial Leadless Pacemaker Implant