Europace Advance Access originally published online on December 18, 2008
Europace 2009 11(2):264-265; doi:10.1093/europace/eun356
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CASE REPORTS
Residual recipient right atrial tissue responsive to atropine 10 years following ‘bi-caval’ orthotopic heart–lung transplantation
1 Cardiac Arrhythmia Center, Cardiovascular Division, Department of Medicine, University of Minnesota Medical School, MMC 508, 420 Delaware Street SE, Minneapolis, MN 55455, USA;; 2 Division of Cardiothoracic Surgery, Department of Surgery, University of Minnesota Medical School, MMC 508, 420 Delaware Street SE, Minneapolis, MN 55455, USA
* Corresponding author. Tel: +1 612 625 4401, Fax: +1 612 624 4937, Email: bendi001{at}umn.edu
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Abstract |
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A 51-year-old-man who had undergone a heart–lung transplant by ‘bi-caval’ anastomosis technique demonstrated residual recipient right atrial (RA) electrical activity responsive to muscarinic blockade 10 years after the surgery. The presumably initially denervated donor RA proved to be responsive to muscarinic blockade as well.
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Case report |
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A 51-year-old-man, who had undergone heart–lung transplant ‘by bi-caval’ anastomosis technique 10 years earlier, presented with a 6-month history of worsening shortness of breath and progressive exercise intolerance. A coronary angiogram 1 year prior to this presentation had been normal, and a recent echocardiogram showed well-preserved left ventricular systolic function. However, surface electrocardiogram revealed an atrial tachycardia (average cycle length of 320 ms) with 2:1 atrioventricular block and an average ventricular rate of 115 bpm.
After an initial unsuccessful attempt to control his susceptibility to tachycardia by drug therapy, he was referred for atrial tachyarrhythmia mapping and ablation. Electrophysiology study revealed the presence of a macro-re-entrant arrhythmia within the right atrium (RA), and radiofrequency ablation was performed along the low lateral RA wall. Following tachycardia termination, two dissociated atrial signals were recorded in the vicinity of the RA ablation site close to the inferior vena cava (IVC) junction (Figure 1, baseline). Further, after administration of atropine (1 mg iv) as part of the post-ablation testing procedure, cycle lengths shortened for both the donor atrium (from 800 to 759 ms) and an apparently dissociated recipient atrial remnant (from 915 to 762 ms) (Figure 1, after atropine). In as much as this patient had had a ‘bi-caval’ anastomosis (i.e. presumably donor IVC to recipient IVC, and donor superior vena cava to recipient superior vena cava) for his heart–lung transplant, a localized autonomically responsive recipient atrial signal at the RA–IVC junction was an unexpected finding, particularly 10 years after surgery.
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Discussion |
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‘Bi-caval’ anastomosis is now a widely used technique for orthotopic heart and heart–lung transplantation. The goal of this surgical approach is to preserve RA integrity and minimize the extent of surgical scar formation in atrial tissue, and in fact, this method has been shown to decrease the incidence of atrial arrhythmias after heart transplantation compared with bi-atrial anastomosis.1
,2 Nonetheless, despite its name, the ‘bi-caval’ technique usually entails leaving a small cuff of recipient RA at the IVC junction both to minimize the risk of the IVC withdrawing below the diaphragm intra-operatively and to facilitate surgical anastomosis of the recipient IVC to the donor RA. As a result, there remains a cuff of recipient RA tissue, and its electrical activity consistent with the dissociated atrial signals is recorded in this case. However, although the recipient atrial cuff may be expected to remain electrically active post-operatively, as is the case in conventional bi-atrial transplantation technique, such activity usually vanishes over a relatively short period of time after surgery (6 months to 2 years).3 Nevertheless, in this instance, not only did the recipient remnant remain active for more than 10 years, its sensitivity to muscarinic blockade also persisted; furthermore, the presumably initially denervated donor RA proved to be responsive to muscarinic blockade as well.
The observations in this case suggest that small atrial remnants may stay viable and neurally connected for long periods post-heart transplantation using ‘bi-caval’ technique. In this regard, it is well known that in certain heart transplant patients, the donor atrium can exhibit evidence of re-innervation over time. For example, among transplant patients in whom large recipient and donor atrial segments remain (i.e. bi-atrial technique), Fitzpatrick et al.4 showed vasovagal responses of both donor and recipient RA at tilt testing and vagal re-innervation of donor hearts, with bi-atrial orthotropic heart transplantation. In such cases, the recipient atrial segments encompass the sinus node region and the posterior aspects of the atria, which are capable of providing access for re-innervation. However, to our knowledge, this phenomenon has not previously been reported in the setting of a ‘bi-caval’ orthotropic heart transplant in which the recipient remnant is small, isolated, and far removed from the recipient sinus node region.
Conflict of interest: none declared.
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[1] Brandt M, Harringer W, Hirt SW, Walluscheck KP, Cremer J, Sievers HH, et al. Influence of bicaval anastomoses on late occurrence of atrial arrhythmia after heart transplantation. Ann Thorac Surg (1997) 64:70–2.
[2] Grant SC, Khan MA, Faragher EB, Yonan N, Brooks NH. Atrial arrhythmias and pacing after orthotopic heart transplantation: bicaval versus standard atrial anastomosis. Br Heart J (1995) 74:149–53.
[3] Holt ND, Hetherington K, Brady S, Dark JH, McComb JM. Electrophysiological properties of the recipient atrial remnant after human orthotopic cardiac transplantation. Europace (1999) 1:187–91.
[4] Fitzpatrick AP, Banner N, Cheng A, Yacoub M, Sutton R. Vasovagal reactions may occur after orthotropic heart transplantation. J Am Coll Cardiol (1993) 21:1132–7.[Abstract]
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