Viennese approach to minimize the invasiveness of ventricular assist device implantation

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1 European Journal of Cardio-Thoracic Surgery 46 (2014) doi: /ejcts/ezu051 Advance Access publication 12 March 2014 ORIGINAL ARTICLE a Viennese approach to minimize the invasiveness of ventricular assist device implantation Thomas Haberl a, Julia Riebandt a, Stephane Mahr a, Guenther Laufer a, Angela Rajek b, Heinrich Schima c,d and Daniel Zimpfer a,d, * Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria b Department of Anesthesiology and Pain Care, Medical University of Vienna, Vienna, Austria c Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria d Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria * Corresponding author. Department of Cardiac Surgery, Medical University of Vienna, Währinger Gürtel 18 20, 1090 Vienna, Austria. Tel: ; fax: ; daniel.zimpfer@meduniwien.ac.at (D. Zimpfer). Received 1 October 2013; received in revised form 29 December 2013; accepted 30 December 2013 Abstract OBJECTIVE: Avoiding full sternotomy and cardiopulmonary bypass (CPB) could significantly reduce the invasiveness of left ventricular assist device (LVAD) implantation. Therefore, we developed minimally invasive implant strategies for the Heartware VAD (HVAD) and the Thoratec HeartMate II (HMII) covering isolated LVAD implantation as well as concomitant valve procedures (aortic/tricuspid). We present the surgical techniques and the initial clinical experience. METHODS: From February 2012 to March 2013, 27 patients (mean age 58 ± 8 years; male 85%; Ischemic Cardiomyopathy 63%; redo surgery 22%; Interagency Registry for Mechanically Assisted Circulatory Support Level I: 29%, II: 22%, III: 33%, IV VII: 16%) underwent minimally invasive LVAD implantation at our department. Apical cannulation was performed via a left lateral minithoracotomy in HVAD patients (n = 20) or a left subcostal incision in HMII patients (n = 7). The outflow graft anastomosis was performed to the ascending aorta via a right minithoracotomy in the second intercostal space (n = 22) or the right subclavian artery (n = 2). If additional valve procedures (aortic/tricuspid) were necessary (n = 3), a hemisternotomy was performed to access the valve and perform the outflow graft anastomosis. Circulatory support for LVAD implantation was CPB (33%), extracorporeal membrane oxygenation (48%) or off-pump (19%). RESULTS: The minimally invasive approach was feasible in all patients with no need for conversions. Thirty-day and in-hospital mortality were 7.4 and 14.8%, respectively. In-hospital stay was 30.0 ± 22.5 days. One patient (4%) died during follow-up from pump thrombus formation. Three patients (11%) underwent surgical revision for bleeding. CONCLUSIONS: Minimally invasive LVAD implantation is feasible and safe. The very encouraging results obtained in this initial series justify a broad application of this technique. Keywords: Ventricular assist device Minimal invasive implantation TX & MCS INTRODUCTION Implantation of mechanical ventricular assist devices (VADs) has become a standard therapy for patients with terminal heart failure despite optimal pharmacological and device treatment. The latest European Society of Cardiology Guidelines recommend implantation of VADs in patients who are otherwise suitable for heart transplantation, to improve symptoms and reduce the risk of hospitalization for worsening heart failure and to reduce the risk of premature death while awaiting transplantation (Class I/B recommendation) and for patients who are not suitable for heart Presented at the 27th Annual Meeting of the European Association for Cardio- Thoracic Surgery, Vienna, Austria, 5 9 October transplantation but are expected to survive >1 year with good functional status as destination therapy (Class IIa/B recommendation) [1]. Minimally invasive techniques have developed as a safe alternative to standard sternotomy in cardiac surgery over the past two decades [2]. These approaches are safe, reproducible [3] and have certain advantages to standard sternotomy. Minimally invasive approaches reduce blood loss, blood product use, infections, intensive care unit (ICU) and in-hospital stay, rehabilitation times and costs and increase thoracic compliance [3, 4]. In particular, elderly and multimorbid patients seem to benefit most[5]. Furthermore, minimally invasive implant techniques preserve the integrity of the pericardium thereby avoiding the negative effects of pericardial opening on right ventricular (RV) function [6, 7]. Given these advantages, left ventricular assist device (LVAD) patients in particular could benefit from a The Author Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

2 992 T. Haberl et al. / European Journal of Cardio-Thoracic Surgery standardized, minimally invasive implant technique avoiding full sternotomy and opening of the pericardium covering the RV. Although the left ventricular (LV) apex and the ascending aorta can easily be reached via different surgical incisions, minimally invasive approaches for LVAD implantation have only been reported in case reports and small series [8, 9]. Therefore, we developed and standardized minimally invasive implantation techniques for the two most commonly used LVAD systems (Heartware VAD [HVAD], Thoratec HMII) as well as typical clinical scenarios including isolated LVAD implantation, additional aortic valve replacement and/or tricuspid valve repair. This has led to a shift in our surgical practice with currently 90% of our VAD implantations performed minimally invasively. We report our initial clinical experience with these new implantation techniques. MATERIALS AND METHODS Inclusion criteria and study design Twenty-seven patients in terminal heart failure underwent minimally invasive LVAD implantation as bridge to transplant, bridge to candidacy or destination therapy from February 2012 to March 2013 at our department and were included in this retrospective analysis. Minimally invasive LVAD implantation has been the primary surgical strategy at our department since February Full sternotomy has been reserved for post-cardiotomy patients, children and patients with a history of left or right thoracotomy since February Primary study end point was feasibility and safety of minimally invasive LVAD implantation. In addition, patient demographics, intraoperative date and postoperative adverse events were analysed. Data were obtained from the Vienna Mechanical Circulatory Assist database. Devices and implantation techniques The Thoratec HeartMate II (HMII) and HVAD were used as LVAD in this series. Both devices have previously been described in detail [10, 11]. While the HVAD can be implanted completely within the pericardium, an extrapericardial pump pocket is necessary for the HMII. Therefore, two different minimally invasive implant techniques were developed and standardized. An overview of implant techniques as well as perfusion strategies for both devices is given in Table 1. Minimally invasive implantation technique Heartware HVAD. Surgical access to the LV apex is gained via an 8-cm incision in the fourth or fifth left intercostal space depending on the exact location of the LV apex as assessed by transthoracic echocardiography. The ascending aorta is exposed through the right second intercostal space via a 6-cm incision. After opening the pericardium over the apex as well as the aorta, an umbilical tape is passed through the pericardium, which is later on used to pull the outflow through the pericardium. In redo cases the outflow graft is tunnelled extrapericardially to avoid intrapericardial dissection. Thereafter, the device is connected to the apex as previously described, the outflow graft is advanced to the ascending aorta and the outflow graft anastomois is performed as shown in Fig. 1A and B. Following deairing, LVAD support is started. We try to close the pericardium over the HVAD whenever possible. Alternatively, we cover the HVAD with a Gore-Tex membrane in order to facilitate dissection at the time of transplantation. Minimally invasive implantation technique Thoratec HMII. For surgical access to the LV apex and dissection of the pump pocket, an 8 10 cm left subcostal incision is performed. After dissection of the subcutaneous tissue, the anterior rectus sheath and the rectus muscle are divided and a pocket of sufficient size to accommodate the HMII pump is prepared. To allow rotation of the outflow graft to the right side, an 8-cm-long incision parallel to the linea alba is carried out medially. The diaphragm is partially detached, and the pericardium is identified and opened over the LV apex. The ascending aorta is exposed through the right second intercostal space via a 6-cm incision. Depending on the diameter of the intercostal space, the right mammary artery is ligated and the second rib detached from the sternum. After opening the pericardium over the apex as well as the aorta, an umbilical tape is passed through the pericardium, which is later on used to pull the outflow graft through the pericardium. In redo cases, the outflow graft is tunnelled extrapericardially to avoid intrapericardial dissection. Table 1: Implantation techniques and perfusion strategies Heartware HVAD Thoratec Heartmate II LVAD only Surgical access Bilateral minithoracotomy Subcostal incision + right minithoracotomy Circulatory support ECMO or off-pump ECMO or CPB LVAD + AVR Surgical access Left lateral minithoracotomy + upper hemisternotomy (3rd ICS) Subcostal incision + upper hemisternotomy (third ICS) Circulatory support CPB CPB LVAD + TV-repair ± AVR Surgical access Left lateral minithoracotomy + upper hemisternotomy (fourth ICS) Subcostal incision + upper hemisternotomy (fourth ICS) Circulatory support CPB CPB ECMO: extracorporeal membrane oxygenation; CPB: cardiopulmonary bypass; ICS: intercostal space; AVR: aortic valve replacement; TV: tricuspid valve.

3 T. Haberl et al. / European Journal of Cardio-Thoracic Surgery 993 Figure 1: (A) Left ventricular apex exposed via a left lateral minithoracotomy. The Heartware HVAD sewing ring has been sutured to the left ventricular apex. (B) Ascending aorta exposed via a right minithoracotomy in the second intercostal space. The outflow graft has been anastomosed to the ascending aorta in an end-to-side fashion. TX & MCS Figure 2: Thoratec HMII implanted via a left subcostal incision and placed in a preperitoneal pocket. Thereafter, the device is connected to the apex as previously described, the outflow graft is advanced to the ascending aorta and the outflow graft anastomosis is performed. Following deairing, LVAD support is started (Fig. 2). Concomitant aortic valve replacement and/or tricuspid valve repair. If concomitant aortic valve replacement is necessary, the ascending aorta is accessed via an upper hemisternotomy in the third intercostal space. In case of concomitant tricuspid valve

4 994 T. Haberl et al. / European Journal of Cardio-Thoracic Surgery repair, the hemisternotomy is advanced to the fourth intercostal space. This incision also allows combined aortic and tricuspid valve procedures. Special situations. In case of severe atherosclerosis of the ascending aorta, the outflow graft anastomosis is performed to the right subclavian artery as previously described [12]. Circulatory support. Circulatory support for isolated LVAD implantation is performed either with ECMO or standard CPB. Arterial cannulation of the ascending aorta is performed through the thoracotomy in the second intercostal space using a straight arterial cannula (Medtronic Biomedicus French) that is advanced over a guide wire. Venous cannulation is preferentially performed by direct cannulation of the right atrium using a right angel cannula (32 or 36 French) or alternatively by percutaneous cannulation in the right groin. Since the introduction of three-dimensional real-time transoesophageal echocardiography, which is extremely useful to rule out LV thrombus or complex LV trabeculations, off-pump implantation is increasingly being performed at our department. However, this technique is only applicable to the Heartware HVAD due to the design of the coring device and sewing ring which allows fast coring and device connection during a short episode of rapid pacing. In case of concomitant valve procedures, cardiopulmonary bypass (CPB) with standard aortic and right atrial or bicaval cannulation is performed. Statistical analysis. Categorical variables were presented as numbers and percentages, mean values and standard deviations (SDs), and 95% confidence intervals (CIs) were determined for continuous variables. Survival was determined using the Kaplan Meier method. RESULTS Patient characteristics We performed 27 minimally invasive LVAD implantations at our centre over a period of 13 months (February 2012 to March Table 2: Patient demographics Variable n =27 Male (n, %) 23 (85.2) Female (n, %) 4 (14.8) Age (mean ± SD, years) 58.6 ± 8.6 Body surface area (mean ± SD, m 2 ) 1.91 ± 0.44 Ischaemic CMP (n, %) 17 (63) Dilative CMP (n, %) 10 (37) INTERMACS level I(n, %) 8 (29.6) II (n, %) 6 (22.2) III (n, %) 9 (33.3) IV-VII (n, %) 4 (14.8) Diabetes (n, %) 4 (14.8) Chronic renal failure (n, %) 4 (14.8) COPD (n, %) 1 (3.7) Redo (n, %) 3 (11.1) COPD: chronic obstructive pulmonary disease; CMP: cardiomyopathy; INTERMACS: Interagency Registry for Mechanically Assisted Circulatory Support. 2013). Mean age at time of implantation was 58.6 ± 8.6 years and 85% of the patients were male. Underlying disease was ischaemic cardiomyopathy in 17 patients (63%) and dilative cardiomyopathy in 10 patients (37%). At the time of implantation, 8 patients (29.6%) were in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) Level I, 6 patients (22.2%) Level II, 9 patients (33.3%) Level III and 4 patients (14.8%) were in Levels IV VII. Patient characteristics are given in Table 2. Seven patients (25.9%) received the LVAD as bridging to transplant, 12 patients (44.4%) as bridging to candidacy and 8 patients (29.6%) as a destination therapy. So far only 1 patient underwent heart transplantation. Mean follow-up was 278 ± 157 days. Procedural data Minimally invasive LVAD implantation was successful in all patients scheduled for this approach during the study period with no intraoperative conversions. The HVAD was used in 20 (74.1%) and the HMII in 7 (25.9%) of patients. One patient (3.7%, HVAD) underwent concomitant aortic valve replacement and 2 patients (7.4%, HVAD n = 1, HMII n = 1) underwent concomitant tricuspid valve repair. In 2 patients (7.4%, both HMII), the outflow graft was anastomosed to the right subclavian artery, due to heavy calcification of the ascending aorta. Circulatory support during LVAD implantation was provided by ECMO in 13 patients (48.1%) with 4 patients (all INTERMACS Level I) already being on ECMO supported prior to LVAD implantation. CPB was used in 9 patients (33.3%). Five (18.5%) patients (all HVAD) underwent off-pump implantation. In 5 patients (18.5%) ECMO support was continued for 1.6 ± 1.3 days to support the right ventricle and pulmonary function [13]. Two of these patients already were supported by ECMO before LVAD implantation. Detailed operative data are given in Table 3. Postoperative outcomes and adverse events Patients were extubated after 4.1 ± 4.5 (range 0 16) days and average ICU stay was 15.9 ± 14.3 days. Three patients (11.1%) underwent surgical revision for bleeding ( pericardial tamponade n = 2, spontaneous retroperitoneal bleeding n = 1). Thirty-day mortality was 7.4% and in-hospital mortality was 14.8%. Causes of death were ischaemic stroke in 2 and necrotizing pancreatitis in 1 patient. Both ischaemic strokes occurred in patients with HVAD devices. One patient (4%) died during follow-up from pump thrombus formation 135 days after implantation. Detailed postoperative data as well as adverse events are given in Table 3. DISCUSSION While minimally invasive surgical techniques have developed as a generally accepted alternative to standard median sternotomy in many fields of cardiac surgery, these techniques have not been standardized for LVAD implantation so far. We developed a standardized approach for minimally invasive LVAD implantation that also covers typical clinical situations including concomitant valve repair/replacement and heavy calcification of the ascending aorta. Minimally invasive techniques are an accepted alternative to median sternotomy and are superior to the standard approach with regard to blood loss, blood product use, infections, ICU and

5 T. Haberl et al. / European Journal of Cardio-Thoracic Surgery 995 Table 3: Outcomes Variable n =27 Circulatory support ECMO (n,%) 13 (48.1) CPB (n,%) 9 (33.3) Off-pump (n,%) 5 (18.5) Operation time (mean, 95% CI, min) ( ) Extracorporeal circulation time (mean, 95% CI, min) 89.0 ( ) Red blood cells (mean, 95% CI, units) 5.7 ( ) Fresh frozen plasma (mean, 95% CI, units) 4.0 ( ) Platelets (mean, 95% CI, units) 1.48 ( ) Ventilation time (mean, 95% CI, days) 4.1 ( ) ICU stay (mean, 95% CI, days) 15.9 ( ) In-hospital stay (mean, 95% CI, days) 42.5 ( ) Bleeding requiring surgical revision (n,%) 3 (11.1) Ischaemic stroke (n,%) 2 (7.0) Haemorrhagic stroke (n,%) 0 (0) ECMO: extracorporeal membrane oxygenation; CPB: cardiopulmonary bypass; ICU: intensive care unit. in-hospital stay, rehabilitation times and costs [3, 4]. In particular, elderly and multimorbid patients seem to benefit most [5]. Hence, especially patients with terminal heart failure who are frail and affected by multiple comorbidities and have an increased risk of postoperative bleeding, infections and respiratory complications might profit form minimally invasive implantation techniques [14]. In contrast, a full sternotomy has the advantage of perfect exposure of the whole heart and great vessels as well as ease for the surgeon. Despite the potential advantages, minimally invasive LVAD implantation for the two most frequently used devices (HVAD and HMII) has only been reported in case reports and small series and how-to-do-it articles so far [8, 15]. The potential benefits of a minimally invasive approach were the driving force behind the development of a standardized surgical technique for minimally invasive LVAD implantation. To minimize the learning curve any new surgical approach is afflicted by, we have adapted surgical approaches with proven feasibility and safety for a standardized and therefore reproducible minimally invasive LVAD implantation technique. The left ventricular apex is approached via either a small thoracotomy directly over the left ventricular apex, identified by transthoracic echocardiography in HVAD patients or a subcostal incision in HMII patients. Both approaches are also used in other fields of cardiac surgery and provide good exposure of the LV apex [15, 16]. For isolated LVAD implantation, the ascending aorta is exposed via a minithoracotomy in the second intercostal space, which also allows central cannulation. This approach has previously been evaluated in aortic valve replacement and is superior to the standard approach with regard to bleeding and ventilation times [17]. In case of concomitant aortic valve replacement or tricuspid valve repair, an upper hemisternotomy is performed instead of a right minithoracotomy. Both procedures have previously been reported to be feasible and safe with this incision [8, 18]. In patients with heavily calcified ascending aortas, the outflow graft is anastomosed to the right subclavian artery. Minimally invasive LVAD implantation including adjunctive procedures to the aortic and tricuspid valve was feasible in all patients in the present series with no intraoperative conversions to sternotomy, despite the fact that we report our initial experience reflecting our learning curve. The observed in-hospital survival of 85% compares with recent survival rates reported for the HVAD and HMII and is appealing considering that 29.6% of patients were in INTERMACS Level I at the time of LVAD implantation [19, 20]. Three patients (11.1%) underwent surgical revision for bleeding, with 2 intrapericardial bleedings and 1 retroperitoneal bleeding that does not relate to the minimally invasive approach. The observed bleeding rates are also comparable with or superior to bleeding rates for both devices with the standard approach [19, 20]. Ischaemic strokes occurred in 2 patients (7.4%, both HVAD), which compares with stroke rates published for both devices [19, 20]. Importantly, we observed no kinking of the outflow graft during the study period. This is a potential concern with the described technique as the outflow graft is pulled through the pericardium, which could result in kinking and flow problems. Operation and support times were comparable with those of the standard operative procedure. No adverse events of complications related to the minimally invasive approach were observed during the whole study period. Nevertheless, ventilation times (mean 4.1 days) and in-icu stays (mean 15.9 days) were rather long in the present series. This is explained by the fact that 29.6% of patients were in INTERMACS Level I and 22.2% in Level II at the time of LVAD implantation. These patients enter the operationwithahighburdenandcannotbeexpectedtorecoverimmediately even with a minimally invasive approach. Limitations The present study is limited by its retrospective design and the lack of a control group. Therefore, we were only able to establish feasibility and safety of the minimally invasive implant technique. No direct comparison with LVAD implantation via a median sternotomy was performed. Conclusion Minimally invasive LVAD implantation is feasible and safe. We have developed a standardized surgical approach that covers not only isolated LVAD implantation but also concomitant aortic and TX & MCS

6 996 T. Haberl et al. / European Journal of Cardio-Thoracic Surgery tricuspid valve procedures. The very encouraging results obtained in this initial series justify a broad application of this technique. Conflict of interest: none declared. REFERENCES [1] McMurray JJ, Adamopoulos S, Anker SD, Auricchio A, Bohm M, Dickstein K et al. ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure 2012: The Task Force for the Diagnosis and Treatment of Acute and Chronic Heart Failure 2012 of the European Society of Cardiology. Developed in collaboration with the Heart Failure Association (HFA) of the ESC. Eur Heart J 2012;33: [2] Schmitto JD, Mokashi SA, Cohn LH. Minimally-invasive valve surgery. J Am Coll Cardiol 2010;56: [3] Mihaljevic T, Cohn LH, Unic D, Aranki SF, Couper GS, Byrne JG. One thousand minimally invasive valve operations: early and late results. Ann Surg 2004;240:529 34; discussion 34. [4] Cohn LH, Adams DH, Couper GS, Bichell DP. 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But the paper lacked some information. It seems to me that you are trying to prove to us that this technique is quite good and can improve the results in patients, but I didn t see a comparison between a historical group and your group. When you see that 50% of your patients are in INTERMACS 1 or 2, the type of patients that are clearly complicated patients, I would expect with this technique a shorter intubation time, ICU stay and hospital stay. I would like a comment from you on the comparison with your historical patients, on whether you are really seeing an improvement in safety and results in this particular group of patients or not. You say, and you state in your introduction, that those patients could benefit during reoperation for transplantation from an easy procedure and probably a safe procedure. I think 14 patients were in the group for bridge to transplant. Did you really see when you transplanted those patients, better results, an easy surgical approach, and a better outcome? Dr Haberl: As you correctly said, almost 50% of the patients were INTERMACS class 1 or 2, they were severely ill, and we saw this opportunity here to present our initial experience with this technique. I agree absolutely that in the future our next work will be the comparison, but it has to be a comparable group. So this is our next work that has to be done, and then we can give you more of that information. Regarding your second question, even though there were 14 patients in the bridge to transplant group, only one patient during this time got transplanted, and according to the reports of this case, I know that we definitely observed a great improvement in surgical access when doing the transplantation. Dr Rabago: Sorry to insist, but when you compare with your historical group (I saw in 2012 you had an equal number of patients with the minimally invasive approach and the standard approach), did you find any difference? Even though I understand you probably cannot give me an exact number, but did you find a difference between the minimally invasive approach and the standard approach? Dr Haberl: Yes, we found a difference, but I will give this to the leader of our programme, Professor Zimpfer. Dr D. Zimpfer (Vienna, Austria): I am the senior author on this paper; let me comment on that. The next step is that we are going to do a propensity score analysis comparing our historic controls to this approach. What we can say so far is that the incidence of right heart failure seems to be lower when we use this approach and the usage of blood products is a lot lower with this approach than with the sternotomy approach.