Right ventricular cardiomyopathy: timing of heart transplantation in Uhl's anomaly and arrythmogenic right ventricular cardiomyopathy
1 Department of Emergency and Cardiovascular Medicine, Institute of Medicine, Sahlgrenska Academy, Göteborg University, Gothenburg 41685, Sweden
2 Division of Cardiology, Queen Silvia Children's Hospital, University of Gothenburg, Gothenburg, Sweden
* Corresponding author. Tel: +46 313435229, Fax: +46 31823241, Email: thomas.gilljam{at}vgregion.se
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Abstract |
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Transplant indications for right ventricular (RV) cardiomyopathy have not been defined. We report on two boys, aged 18 and 17 years, one with arrhythmogenic right ventricular cardiomyopathy (ARVC) and one with Uhl's anomaly. Both had implantable cardioverter defibrillator (ICD) for the prevention of sudden death (SD), but were not considered urgent heart transplant candidates due to the absence of heart failure symptoms. A ventricular tachycardia-induced cardiac collapse occurred at school in the Uhl patient and in hospital in the ARVC patient. In both patients, ICD shocks intermittently restored sinus rhythm but with inadequate circulation. Only the ARVC patient received early chest compressions and was saved to heart transplantation. Due to RV failure, both patients had evidence of Fontan-type physiology, in whom pulmonary blood flow is passive and propelled by the transpulmonary pressure gradient and intrathoracic pressure alterations produced by breathing. In these cases, at resuscitation, systemic circulation is not established until after pulmonary blood flow is restored by breathing or chest compressions. An ICD alone is therefore not sufficient for the prevention of SD. When invasive data show evidence of Fontan-type circulation, the patient may be considered for heart transplantation.
Key Words: Uhl's anomaly • Arrhythmogenic right ventricular cardiomyopathy • Arrhythmogenic right ventricular dysplasia
Received March 10, 2008; Revised July 8, 2008; Accepted October 23, 2008
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Introduction |
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Arrhythmogenic right ventricular cardiomyopathy (ARVC) involves progressive fibrous and fatty replacement of myocardium in the inflow, apical, and outflow portions of the right ventricle (RV), resulting in ventricular tachycardia (VT) with incurrent risk of sudden death (SD) and, in a proportion of cases, progressive RV dysfunction.1–8 ARVC affects approximately 1/5000 people, with a variable proportion of cases being hereditary.1 In the comparatively rare Uhl's anomaly, there is complete absence of myocardium in the RV free wall, typically leading to RV failure in childhood and, to a lesser extent, VT.2,9,10 Although Uhl's anomaly is a separate clinical entity, it has been considered as the extreme variant of ARVC.2
ARVC diagnosed during adulthood has recently been shown to have a good prognosis.3–5 Implantable cardioverter defibrillator (ICD) treatment offers appropriate long-term protection in over 90% of the patients,5 the median life expectancy exceeds 50 years,3,4 and only 5–10% progress to overt RV failure.3,4
In contrast, ARVC in childhood and adolescence, which accounts for 5–30% of the cases,7,8 has a far more uncertain prognosis and may constitute 30–50% of all SD in ARVC.7 In almost 50% of the patients, there is severe dilatation and reduction of RV ejection fraction, although relatively few progress to overt heart failure.7,8
We have recently, within a short time span, encountered two teenage patients with RV cardiomyopathy: one with ARVC and one with Uhl's anomaly. Both patients had a similar clinical picture with RV dysfunction, VT, and syncopal episodes. Both had ICD treatment and were, wrongly, denied ‘elective’ heart transplantation. Both patients soon thereafter experienced repeated VT (‘electrical storm’), from which only the ARVC patient, due to fortunate circumstances, was saved to emergency heart transplantation.
We take this opportunity to discuss the Fontan-like haemodynamics in RV dysfunction, its consequences at resuscitation, the safety of ICD treatment, and, finally, the impact this may have on the timing of heart transplantation.
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Case reports |
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Case 1: arrhythmogenic right ventricular cardiomyopathy
This 14-year-old boy presented with exercise-induced syncope. Exercise capacity and blood pressure response were normal. The ARVC diagnosis was confirmed by polymorphic left-bundle-branch block VT, dilated RV with decreased contractility, and tricuspid regurgitation on echocardiography and magnetic resonance imaging (MRI) (Figure 1A). Myocardial biopsy showed fibro-fatty infiltration (data not shown). To prevent SD, an ICD was inserted and sotalol prophylaxis was initiated. The following 4 years were without symptoms or ICD discharge. At the age of 18 years, the patient had an exercise VT with ICD discharge. Echocardiography showed deteriorating RV function with an apical thrombus formation but normal left ventricular function. Exercise capacity had dropped to 65% of the predicted value, with a significant exercise blood pressure drop from 133 to 105 mmHg. A transplant was not considered warranted at this point in view of the relatively preserved exercise capacity.
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During the following month, the thrombus resolved on warfarin, but there was progressive daily VT without ICD discharge. In view of further deterioration of RV function on echo, he was admitted for transplant work up. There were no signs of myocarditis. Cardiac catheterization showed Fontan-type physiology with equilibrated pressures of 21–25 mmHg in the right atrium, RV, and pulmonary artery with non-pulsatile pulmonary blood flow (Figure 1B). Cardiac output was maintained at 4.3 L/min (cardiac index 2.2 L/min) despite severe tricuspid regurgitation.
He experienced an in-hospital cardiac arrest the following day. Repeated ICD shocks resulted in intermittent sinus rhythm, but circulation was insufficient. Adequate circulation was only established after 2 min of chest compressions. After 3 days in the intensive care unit, the patient underwent an emergency cardiac transplant. The post-transplant course has been uneventful.
Case 2: Uhl's anomaly
This boy also presented at age 14 years due to exercise-induced syncope. He had normal exercise capacity, but blood pressure drop during exercise testing. Holter revealed multifocal RV ectopy and a short VT of 5 s. Echocardiography showed a thin-walled poorly contracting RV and MRI demonstrated a thin RV wall throughout, suggestive of Uhl's anomaly (Figure 2A). As the syncope was considered to be due to blood-pressure drop and not due to VT, he did not receive an ICD but was put on propranolol prophylaxis. At 17 years, he had three additional syncope episodes, the last of which was due to torsade de pointes from which he was resuscitated. He received an ICD but a transplant was not considered warranted as MRI and echocardiography showed no significant progress.
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Three months later, without previous symptoms of myocarditis, heart failure, or arrhythmia, he experienced palpitations and near syncope at school. In spite of repeated ICD shocks, he reverted to semi-unconsciousness. External defibrillation was continued by the emergency team after confirmation of VT. In spite of intermittent sinus rhythm, circulation was not restored and he succumbed 2 h later at the local hospital (where cardiac assist device was not available). Autopsy confirmed the diagnosis of Uhl's anomaly with epicardial fat, but no fibro-fatty infiltration between the endo- and the epicardial layers (Figure 2B).
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Discussion |
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We have presented two cases of right ventricular cardiomyopathy with different diagnoses but with a similar clinical picture, including RV dysfunction and ICD treatment due to VT. Although the RV dysfunction was significant, the patients were not considered as cardiac transplant candidates in view of their relatively mild symptoms. Both patients, nevertheless, experienced cardiac arrest from which the ICD alone could not resuscitate them. We believe that this poor response to ICD therapy may be due to the Fontan-like physiology in RV dysfunction, which was demonstrated in the ARVC case and can be reasonably inferred from non-invasive data in the Uhl's anomaly case.
In Fontan circulation, the post-capillary blood pressure is not ‘wasted’ in the systemic veins, but is maintained at 15–25 mmHg into the pulmonary artery.11 The pulmonary blood flow is passively propelled by the transpulmonary pressure gradient to the left atrium (Figure 1B), but may be augmented by alternations in thoracic pressure such as breathing or chest compressions.11–14 In this circulation, conversion to sinus rhythm during resuscitation after cardiac arrest does not immediately result in pulmonary venous return, which is the prerequisite for left ventricular filling and coronary and systemic circulation. Only after restoring the pulmonary blood flow, which can be performed by chest compressions, as in this ARVC case, or by elevating venous pressure by profuse intravenous fluid administration, as in another Fontan case,12 can this be accomplished. Consequently, ICD treatment alone may not be sufficient to prevent SCD in Fontan physiology.
Although prognosis for most ARVC patients after ICD treatment is good,5 cardiac transplantation may be the final option for a few ARVC as well as for Uhl's anomaly patients. There are reports on cardiac transplantation in seven ARVC patients3–6 as well as one with Uhl's anomaly,10 but also a report of death on the transplant waiting list.3 Transplant indications were severe right (and left) ventricular dysfunction, and, in three cases,3,5 concomitant arrhythmia. No concurrent catheterization data are presented, and the timing of transplantation is not discussed.
In left-sided cardiomyopathy, transplant indications and the timing of transplantation have been defined.15 As RV cardiomyopathy is relatively rare, knowledge about right heart and pulmonary haemodynamics, especially during arrhythmia, is incomplete. Transplant timing in these cases is therefore a more crucial task.
When assessing the severity of RV cardiomyopathy, ventricular angiogram and more recently MRI are the gold standards.1,7 We suggest that right heart catheterization should be performed in all the cases, which show signs of RV dysfunction. If there are increased filling pressures, suggesting Fontan-type physiology, the patient may respond insufficiently to ICD therapy and should therefore be considered for heart transplantation. Nevertheless, for the majority of ARVC and stray Uhl patients, currently recommended ICD prophylaxis will be sufficient.3–5
Conflict of interest: none declared.
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