Abstract
We report on a patient with ischaemic dilated cardiomyopathy, who developed progressive regurgitation of his native aortic valve after implantation of a left-ventricular assist device (LVAD, HeartMate II). Increasing regurgitant volume led to reduced effective cardiac output and worsening of symptoms. To overcome aortic regurgitation, we successfully closed his aortic valve minimally invasively using the Amplatzer® P.I. Muscular VSD Occluder. This led to instant haemodynamic stabilisation. We observed significant residual regurgitation through the Occluder during the initial phase, which led temporarily to increased haemolysis and subsequently to worsening of kidney function; once the haemolysis ceased, we noted a very good interventional and clinical result at short-term follow-up.
1 Introduction
1.1 Case report
A 73-year-old male patient suffering from end-stage ischaemic dilated cardiomyopathy was referred to our institution for implantation of a long-term left-ventricular assist device (LVAD, HeartMate II®) as destination therapy. The patient’s postoperative course was uneventful; he was discharged home after 2 months. Four weeks later, he was re-admitted with recurrent complaints of shortness of breath at rest, episodes of poor oxygenation, increased exercise intolerance, and worsening symptoms of dementia due to pulmonary oedema consistent with low cardiac output syndrome.
On initial evaluation, we observed unusually elevated LVAD flow rates at rest. We identified the underlying cause to be severe regurgitation of the native aortic valve, an anomaly not present at implantation and initial discharge. In fact, the patient received trans-oesophageal echocardiography (TEE) prior to LVAD implantation with no observable aortic regurgitation. Sinus of Valsalva was assessed as 36 mm prior to LVAD implantation and 37 mm at time of diagnosis of aortic regurgitation. With the native left ventricle’s low output, the aorta began to regurgitate, creating an artificial circulatory loop with reversed flow in the ascending aorta and via the left ventricle back to the LVAD. Neither medical therapy nor LVAD adjustments led to lasting re-stabilisation. To disrupt the circulatory loop, we closed the aortic valve percutaneously by employing an Amplatzer® P.I. Muscular VSD Occluder (AGA). Computed tomography revealed the aortic valve ‘annulus’ measuring on average 22 mm. We thus chose the largest ventricular septal device (VSD) device available, with a 24 mm stent diameter at the level of the connecting waist. The procedure was performed in the operating room using a portable C-arm and TEE for peri-interventional imaging ( Supplement Movie 1 and 2). The occluder was implanted successfully via the left subclavian artery using a 12F sheath. The patient’s haemodynamics improved immediately. We observed no atrioventricular (AV) block, no mitral valve impairment and no coronary artery occlusion. The device was well positioned on computed tomography (CT) (Fig. 1 ). However, some residual aortic regurgitation through the occluder was detectable. Transient haemolysis with renal impairment occurred, which resolved gradually with conservative management, requiring a total of 23 units of blood (red blood cells (RBCs), each 300 ml) during the first 6 weeks after implantation. To facilitate closure of the occluder, both heparin and coumadine were discontinued on day 10 post-implantation for a total of 6 weeks and substituted by aspirin and clopidogrel for this time span. At the time of discharge, echocardiography displayed very little residual regurgitation across the occluder, reflected by renal-function recovery and the resolution of haemolysis. Unfortunately, our patient died because of a fatal handling error while changing the LVAD’s rechargeable batteries at home several weeks later. Closing remarks in the autopsy confirmed the occluder’s correct position at the level of the aortic valve, close to the coronaries, but without occluding their orifices. Furthermore, the pathologist observed no thrombi in the LVAD system (Fig. 2 ).
Computer tomographic images of the device post-implantation depicting the position in relation to the mitral valve ((A) sagittal oblique view), the coronary orifices ((B) double oblique transverse view); LV and aorta with LVAD-cannula and VSD-Occluder in situ (C, coronal view).
Autopsy findings: correct position of the VSD-Occluder at the level of the aortic valve ((A) caudal view form the LV cavity), close to the coronaries, but without occluding their orifices ((B) cranial view with the aortal disc and a probe in both coronaries).
2 Discussion
Implantable assist devices are increasingly used in patients suffering from end-stage heart failure, particularly as LVADs for long-term support. LVAD malfunction is an important cause of morbidity and mortality. Acquired native aortic valve disease may be caused by aortic root diameter enlargement or thrombus formation and commissural fusion [1–4]. In a recent study by Pak et al. de novo aortic regurgitation was observed in up to 15% of patients post implantation of a HeartMate II device and may be associated with aortic root enlargement [3]. Significant aortic regurgitation leads to an adverse perfusion mismatch with relatively elevated LVAD flow and inadequate systemic perfusion. The disruptive artificial circulatory loop can only be abolished by closing the aortic valve. Surgical techniques in this setting have been described, and suture closure or oversewing with a patch is recommended [5,6].
Our strategy was to close the aortic valve percutaneously by implanting an Amplatzer® device with self-expanding double discs and its connecting waist, which usually acts to stent septal defects [7]. This stabilising-stent principle was a priority while considering the patient’s need for the device. By selecting the Amplatzer® P.I. Muscular VSD Occluder, we accepted relatively long stent portions (waist length 10 mm); in fact, the aortic disc almost touched the coronaries – ultimately without occluding their orifices; the same applied to the mitral valve, which was not impaired either. An Amplatzer® Septal Occluder with its flat design (waist length 4 mm) would have been a good alternative, but the larger left-sided disc might have impaired the mitral valve function.
Riede et al. recently reported a case describing successful trans-catheter closure of the aortic valve in an infant after stage-1 palliation for hypoplastic left heart with severe aortic regurgitation. Due to the infant’s size, the smallest Amplatzer® Septal Occluder was chosen, and implanted via an antegrade transvenous approach with an excellent result [7,8]. However, to our knowledge, the case we present here is the first report on trans-catheter closure of the aortic valve in an adult on LVAD support. Given the close proximity to the apical LVAD cannula, we refrained from an antegrade approach. As the limited length of currently commercially available introducer sheaths did not permit a transfemoral approach (distance to LV >100 cm), we chose the subclavian artery approach.
The occluder was implanted in a straightforward manner, haemodynamics stabilised immediately and further cardiac decompensation was prevented. However, serious haemolysis did occur during the post-interventional course, leading to transient renal impairment and the need for numerous blood transfusions during the first weeks. Haemolysis is rare but is common in conjunction with the Amplatzer® Muscular VSD Occluder and is usually associated with residual shunting. Complete closure rates are reported to be less than 50% within the first 24 h, rising to 70% and 92% after 6 and 12 months, respectively [8]. Device explantation must be considered if serious haemolysis persists [9]. The axial LVAD system also contributes to erythrocyte damage [10]. To facilitate closure of the large occluder, we changed to dual anti-platelet therapy with no systemic clot formation or neurological events. To summarise, we observed an excellent interventional result at short-term follow-up. However, it has to be stated that this is a single case report on an off-label use of an Amplatzer® Occluder and no data on long-term outcome exist. Thus, the approach presented has to be considered as experimental and outcome cannot be considered clearly predictable.
3 Conclusion
Trans-catheter aortic valve closure is feasible with an Amplatzer® P.I. Muscular VSD Occluder when significant aortic regurgitation occurs during LVAD support. The need for a large occluder is accompanied by the risks of coronary artery obstruction and mitral valve damage as well as serious haemolysis. The availability of an occluder with a shorter connecting waist and an extra-long sheath for the transfemoral approach would be helpful technical improvements for future interventions.
Presented at the 24th Annual Meeting of the European Association for Cardio-thoracic Surgery, Geneva, Switzerland, September 11–15, 2010.
References
Appendix A Supplementary data
Supplementary data associated with this article (Supplementary Data and Supplementary Data) can be found, in the online version, at doi:10.1016/j.ejcts.2011.01.036.
