Europace Advance Access originally published online on March 16, 2006
Europace 2006 8(4):279-282; doi:10.1093/europace/eul006
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
PACING
Electromechanical synchronization of the heterotopic and native heart by dual atrial stimulation following heart transplantation
1 Department of Cardiac SurgeryInnsbruck Medical UniversityAnichstr. 35, 6020 Innsbruck, Austria Europe; 2 Department of Cardiology, Internal MedicineInnsbruck Medical UniversityAustria Europe; 3 Department of Radiology IInnsbruck Medical UniversityAustria Europe; 4 Department of Anaesthesia and Intensive Care MedicineInnsbruck Medical UniversityAustria Europe
Manuscript submitted 21 June 2005. Accepted after revision 22 January 2006.
* Corresponding author. Tel: +43 512 504 25952; fax: +43 512 504 25953. E-mail address: herwig.antretter{at}uibk.ac.at
 |
Abstract |
|---|
 Top Abstract IntroductionCase reportDiscussionReferences |
|---|
After heterotopic heart transplantation, a 59-year-old woman presented with remarkable symptoms of breathlessness and fatigue, despite excellent donor heart function. Asynchrony of donor and native heart provoked haemodynamic instability. Dual atrial pacemaker implantation lead to linkage and synchronization of atrial and ventricular contraction in both the donor and native heart with the faster organ executing the synchronization. Remarkable relief of symptoms has been evident during the long-term follow-up.
Key Words: Heterotopic heart transplantation, Dual atrial pacemaker implantation
|
Introduction |
|---|
|
TopAbstractIntroductionCase reportDiscussionReferences |
|---|
Patients requiring heart transplantation normally are transplanted with the donor organ in orthotopic position (oHTX).1
A specific subset of patients, most of them suffering from fixed pulmonary hypertension, need heterotopic heart transplantation (hHTX) with the donor heart in abnormal anatomical position. This should result in two hearts acting in parallel, each contributing to antegrade flow.2,3
However, natural progression of the underlying disease of the native heart may lead to further clinical detoriation several years after transplantation.4 Compensation by the transplanted heterotopic graft is frequently not possible. Sometimes competitive contractions of the two hearts cause haemodynamic instability with worsening of exercise capacity.
|
Case report |
|---|
|
TopAbstractIntroductionCase reportDiscussionReferences |
|---|
A 59-year-old female patient suffering from severe ischaemic heart disease underwent hHTX on 7 January 2002 because of markedly elevated fixed pulmonary hypertension. The transplanted organ was resected from a 37-year-old female donor with lethal cerebral injuries after suicide.
Despite an uneventful post-operative course, the patient presented diminished functional capacity during the following 1.5 years with dyspnoea, fatigue, and palpitations (NYHA class III).
Holter monitoring excluded paroxysmal arrhythmias of both hearts. Repeated endomyocardial biopsies of the heterotopic donor graft revealed no relevant rejection episodes. Atrioventricular (AV) conduction disturbance was excluded and Wenckebach point was measured for the native heart (165 bpm) and the heterotopic graft (210 bpm). Transthoracic as well as transoesophageal echocardiography of the transplanted graft showed normal systolic left ventricular ejection fraction (LVEF), normal dimension of the right ventricle, and no valve incompetence. The native heart presented the well-known highly reduced LVEF, no thrombi, and a mitral insufficiency grade I. The most likely explanation for the haemodynamic instability was the asynchrony of both hearts (Figure 1).
|
Therefore, it was decided to synchronize electrically the two hearts in order to optimize haemodynamic and clinical status.
In December 2003, a biatrial pacemaker system was implanted (St Jude Medical, FrontierTM Model 5510; SJM Inc., St Paul, MS, USA) with screw-in leads in both right atria of the native as well as the heterotopic heart (Figure 2).
|
With this pacemaker model, designed for biventricular stimulation in the context of heart failure therapy, both atrial leads were connected to the ventricular channels and the atrial channel was closed with a dummy connector. The pacemaker was programmed in VVT mode (in this case equivalent to AAT) with a trigger time of 13 ms. Stimulation of both atria was therefore carried out with a delay of 13 ms, whereby the heart with the higher own frequency always became the leading organ. Therefore, the P-wave of the instantaneously faster heart is sensed, and after 13 ms, the second atrium is stimulated, whereas stimulation of the sensed atrium is impossible because it is refractory.
This results in bidirectional electromechanical coupling, with the faster heart triggering the synchronization.
With this pacemaker model, true bipolar sensing in both atria and less requirement for additional hardware (no need for further lead connectors) could be realized.
Immediately after pacemaker implantation, a distinct harmonization of the invasive measured aortic blood pressure curve was observed (Figure 3). Also, the cardiac output increased from pre-operatively 4.2 to 4.9 L/min after pacemaker insertion. Clinical condition improved steadily during the first post-operative days resulting in improved physical capacity without adjustment of medication. The patient's walking distance on the 6-min walk test increased 
33% from 347 to 460 m. Three floors could be mounted without rest or shortness of breath.
|
The latest clinical evaluation took place in February 2005, and further clinical improvement could be observed. The patient is now in NYHA class II and comfortable with the distinct amelioration of quality of life; the 6 min walk test further increased to 490 m.
|
Discussion |
|---|
|
TopAbstractIntroductionCase reportDiscussionReferences |
|---|
The main reason for pacemaker implantation after heart transplantation is chronotropic incompetence due to sinus node dysfunction of the donor heart. This problem was frequently observed as long as the standard biatrial technique described originally by Shumway et al.5
was used for orthotopic heart transplantation. Larger series have reported permanent pacemaker implantation in >10% of transplanted patients.6 Modification of the implantation technique in leaving the right donor atrium intact by using the bicaval implantation technique4 minimizes post-operative sinus node dysfunction and reduces the need for permanent pacemaker implantation after oHTX.7,8
Heterotopic heart transplantation with implantation of the auxiliary donor heart into the right pleural cavitiy and corresponding anastomosis to the recipients own myopathic organ was clinically established by Losman and Barnard.9 As this method has relatively few specific indications, it is rarely performed. The greatest disadvantage of hHTX is the ongoing detoriation of the poorly contracting recipients own heart, leading to massive problems during long-term follow-up.10
Normally, the donor and recipient hearts are allowed to beat asynchronously, the flow into both hearts depends on compliance and ventricular contractility. Reports about permanent cardiac pacing after hHTX are rare. In 1992, Breedveld et al.11 reported an AV-sequential pacemaker implantation in a patient after hHTX, with the atrial lead positioned in the right ventricle of the donor heart and the ventricular lead in the atrium of the recipient heart in order to synchronize both heart rates. With an increased AV interval of 300 ms, contraction of the recipient heart just preceded that of the donor heart, resulting in relief of symptoms and improvement in exercise tolerance. The paced linkage improved systolic performance of the recipient heart by reducing its afterload. Morris-Thurgood et al.2 could also demonstrate these functional improvements in both hearts after paced linkage in 11 heterotopic transplant recipients.
In 1996, Fenelon et al.12 described a successful radiofrequency ablation of the His bundle of a native heart with drug-resistant atrial flutter and fast ventricular response in a patient after redo hHTX. Consecutively, a dual chamber pacemaker was implanted (atrial lead positioned in the atrium of the donor heart and ventricular lead in the right ventricle of the native heart) to re-establish synchronization of the two hearts. Exertional angina and breathlessness improved markedly.
Our case report demonstrates the feasibility of true simultaneous biatrial stimulation using advanced pacemaker technology: linkage of both hearts, authentic bipolar sensing in both atria and substantial AV sequential contraction in the donor and native heart, and bidirectional electromechanical coupling with the faster organ executing the synchronization. The remarkable relief of symptoms, which was achieved immediately after pacemaker implantation, is still evident more than 1.5 years after the procedure. No adjustment of medications took place during the invasive procedure and long-term follow-up.
The true sequential pacing of both hearts, which was described formerly,2,11,13 was also tested in our case in the cath-lab but did not eliminate patient's haemodynamic instability.
We are aware of the fact that despite electromechanical synchronization of the donor and recipient hearts at an atrial level, true ventricular synchronization is not always possible: sinoatrial conduction time, impulse propagation via the AV node, and the His–Purkinje system differ between a healthy (donor) heart and a diseased, dilated (recipient) heart, with distinct reduction in LVEF. For this reason, depolarization at ventricular level can vary in the range of milliseconds between the two hearts.
|
References |
|---|
|
TopAbstractIntroductionCase reportDiscussionReferences |
|---|
[1] Shumway NE. Thoracic transplantation. World J Surg 2000; 24: 811–4.[Medline]
[2] Morris-Thurgood J and Cowell R, et al. Cardiac transplantation: hemodynamic and metabolic effects of paced linkage following heterotopic cardiac transplantation. Circulation 1994; 90: 2342–7.
[3] Nakatani T, Frazier O, Lammermeier D, et al. Heterotopic heart transplantation: a reliable option for a select group of high-risk patients. J Heart Transplant 1989; 8: 40–7.[Medline]
[4] Antretter H and Laufer G. Surgical techniques for cardiac transplantation. Eur Surg ACA 2001; 33: 17–24.[CrossRef]
[5] Shumway NE, Lower RR, Stofer RC. Transplantation of the heart. Adv Surg 1966; 2: 265–84.[Medline]
[6] Herre JM, Barnhart GR, Llano A. Cardiac pacemakers in the transplanted heart: short term with the biatrial anastomosis and unnecessary with the bicaval anastomosis. Curr Opin Cardiol 2000; 15: 115–20.[Medline]
[7] Parry G, Holt ND, Dark JH, McComb JM. Declining need for pacemaker implantation after cardiac transplantation. Pacing Clin Electrophysiol 1998; 21: 2350–2.[CrossRef][Medline]
[8] Trento A, Takkenberg JM, Czer LSC, et al. Clinical experience with one hundred consecutive patients undergoing orthotopic heart transplantation with bicaval and pulmonary venous anastomoses. J Thorac Cardiovasc Surg 1996; 112: 1496–503.
[9] Losman JG and Barnard CN. Hemodynamic evaluation of left ventricular bypass with a homologous cardiac graft. J Thorac Cardiovasc Surg 1977; 74: 695–708.[Medline]
[10] Antretter H, Pölzl G, Margreiter J, et al. Successful transfer of a cardiac allograft from a heterotopic to an orthotopic position 16 years after heart transplantation. Transplantation 2002; 74: 540–3.[Medline]
[11] Breedveld RW, van Gelder LM, Mitchell AG, Peels CJ, Yacoub M, el Gamal MIH. Optimized hemodynamics by implantation of a dual chamber pacemaker after heterotopic cardiac transplantation. Pacing Clin Electrophysiol 1992; 15: 274–80.[Medline]
[12] Fenelon G, Goethals M, Brugada P. Two hearts beating as one: radiofrequency ablation of the His bundle in a heterotopic heart transplant patient. Pacing Clin Electrophysiol 1996; 19: 374–5.[Medline]
[13] Beyer E, Vatcharasiritham C, Sweeney M, et al. Linked pacing after heterotopic heart transplantation with concurrent left ventricular reduction of the native heart. Tex Heart Inst J 1998; 25: 299–302.[Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||