PhD in Bioengineering and Medical-Surgical Sciences

Transcription

1 PhD in Bioengineering and Medical-Surgical Sciences Research Title: Influence of different perfusion and aortic clamping techniques in minimally invasive mitral valve surgery Funded by None Supervisor Contact Mauro Rinaldi Mauro Rinaldi Context of the research activity Minimally invasive mitral valve surgery (MIMVS) has become one of the most innovative approach in cardiac surgery in the last few years. To date, different perfusion and aortic clamping techniques have been reviewed: retrograde arterial perfusion (RAP) through the femoral artery with Endoreturn/Intraclude (P+EB) system (Edwards Lifesciences, Irvine, California), RAP with trans thoracic clamp (P+XC), antegrade arterial perfusion with the Endodirect system (C+EB) ( Edwards Lifesciences, Irvine, California), and RAP with fibrillating heart. However the optimal setting of cardiopulmonary bypass during right mini thoracotomy MVS remains controversial Port Access surgical technique and C+EB technique has been previously described. Double lumen endotracheal tube is positioned to allow one lung ventilation and bilateral radial arterial lines are used for monitoring blood pressure. The latter is particularly important in case of P+EB technique so that migration of the endoaortic balloon can be appreciated. Surgical approach is a right mini thoracotomy in the 4 th intercostal space (4 6 cm) without ribs retraction. Using a soft tissue retractor, the surgical port is exposed. To improve the vision, an Olympus endoscope is usually inserted in an accessory port created below the working port. Arterial perfusion is obtained with the P+EB cannula (21 23Fr

2 Edwards ) through the femoral artery or with the C+EB aortic cannula (24Fr Edwards ) through the right 1 st intercostal space), or with a standard femoral artery cannulation. In the first and second case, clamping and cardioplegia delivery is gained through a balloon catheter (Intraclude, Edwards Lifescience) inserted through the sidearm of the arterial cannula; in case of standard femoral artery cannulation a Chitwood trans thoracic clamp is used and the cardioplegia is delivered through a 7Fr cardioplegia needle (CalMed Technologies, CA) placed into the ascending aorta at its highest point. Venous return is routinely obtained with a double cannulation: jugular cannulation is always achieved percutaneously using a 17 21Fr Medtronic cannula or using a 18 20Fr Edwards cannula (OptiSite); femoral cannulation is performed percutaneously in all the cases of simultaneous central aortic cannulation. In the case of P+EB or standard femoral artery cannulation a minimal groin incision is necessary and both arterial and femoral cannulation are directly performed using Seldinger technique. Compared with conventional surgery, MIMVS is associated with optimum outcomes, even if concerns still remain about neurological complications. The risk of stroke in consequence of MIMVS, varies from 2 to 10% as reported by various studies and registries. This risk is increased considering transient clinical events and clinically silent infarcts (not associated with immediate and evident neurological deficit) theoretically capable of determining alterations of the neuropsychological profile of the patient and detectable with specific imaging modalities as magnetic resonance (MR).The purpose of the research program blinded study is evaluate major and minor neurologic event in patients undergoing MIMVS and to identify the impact of different aortic clamping and perfusion techniques in the setting of MIMVS. The incidence of neurologic events in MIMVS compared with that of conventional surgery is a controversial issue and has been extensively studied. In a meta analysis published by Modi, equal occurrence of neurologic events between patients who underwent MIMVS and those who underwent a median sternotomy was found. Conversely, the Thoracic Surgeons Adult Cardiac database and the Cleveland Clinic group concluded that the risk of stroke is significantly higher in the less invasive group. Moreover, recent data have suggested that retrograde arterial perfusion (RAP), particularly in patients with severe arch/ascending aortic

3 atherosclerosis, could be the source of the significant increase in the incidence of cerebral complications. The meta analysis of Cheng, documents a 1.79 fold increase in the risk of stroke in MIMVS group, but on subgroup analysis this appeared driven by a higher stroke risk in those studies reporting endoaortic balloon occlusion and not transthoracic clamping. Murzi et al. report a 4.28 fold increase in stroke risk with RAP in 1280 primary MIMVS patients. Grossi and colleagues show that the only significant risk factor for neurologic event was the use of retrograde perfusion in high risk patients with aortic disease. The University of Turin, Surgical Sciences Department, Cardiac Surgery Division is a well known unit experienced in minimally invasive cardiac procedure. Prof Rinaldi and colleagues are leader in this field. The longstanding collaboration between surgeons, anesthesiologists, perfusionists and OR nurses allowed the team to be one of the most important training center in Europe for minimally invasive cardiac procedures. Since 1997 Prof Rinaldi and colleagues have performed more than 1500 minimally invasive cardiac operations with excellent results presented at the most important meetings and on the most prestigious journals. The team has an active collaboration with Neurologists and NeuroRadiologists such as with statisticians in order to evaluate all the different aspects of outcomes. Hypothesis and significance: Objectives To determine the number and impact of microembolic events during MIMVS on clinical neurological, general cognitive and neuropsychological status, and on MR evaluation. We also aim to determine if different techniques of perfusion and aortic clamping may impact on early outcomes including neurologic impairment. Specific aims Aim 1: To determine the incidence in new lesions on pre discharge MR in patients undergoing MIMVS according to different vascular access and aortic clamping techniques. Aim 2:

4 To assess the correlation between clinical neurological periprocedural events (TIA, Stroke), cognitive / neuropsychological status impairment and the occurrence of new lesions on predischarge MR. Aim 3: To assess the evolution of new cerebral ischemic lesions between pre discharge MR and follow up MR (3 months later). Experimental Design Aim 1: Patients who have no contraindications will undergo cerebral MR before MIMVS and after pre operative angiography as a baseline assessment and then, they will be randomized in one of the 3 groups. If no contraindications arise in the postoperative period (eg definitive pacemaker implantation), patients will undergo cerebral MR before the discharge, to highlight the presence of new ischemic lesions, even clinically silent. MR evaluation will be performed by blinded radiologists. MR will be performed with a 3T system (Philips INGENIA 3T). The protocol includes conventional sequences for the morphological and quantitative assessment (3D FLAIR, 3D T1 TSE, DWI, T2 FFE) and non conventional sequences for the white matter microstructural evaluation (Diffusion Tensor Imaging DTI with fractional anisotropy and mean diffusivity). No contrast enhanced will be used. The number of patients in the different groups with new ischemic lesions at the pre discharge MR will be compare with the Chi square test. Experimental Design Aim 2: Neurologic and cognitive assessment will be performed by blinded specialists of the Neurology Department. All patients enrolled in the study will be submitted to a basic assessment before the MIMVS with the following texts: National Institute of Health Stroke Scale, Rankin Scale, Montreal cognitive Assessment, and Mini Mental State Examination. The aim of this evaluation is to highlight focal neurological deficits, degree of autonomy, behavioral aspects such as anxiety and depression and general cognitive status. These evaluations will be repeated after 3 months. Experimental Design Aim 3: After 3 months, patients who developed new ischemic lesions revealed by the post operative cerebral MR will repeat a new MR

5 to assess evolution of cerebral damage. Skills and competencies for the development of the activity The applicant should have experience in the field of minimally invasive cardiac surgery and mitral valve procedures. She/he has to be committed to work for development, seeking and testing improvements. She/he will need to work collaboratively in a team to set standards and procedures that achieve a high level of quality, and productivity. In addition to the technical knowledge and skills, the applicant should further develop skills that enhance her/his performance in the current role and are transferable to other positions or roles. These skills may include interpersonal and management skills.