Magnetic Resonance Neurological Evaluation After Right Mini-thoracotomy Mitral Valve Surgery: Trans-thoracic Versus Endoaortic Clamp

The incidence of neurologic events in right mini-thoracotomy mitral valve surgery compared with that of conventional surgery is a controversial issue and has been extensively studied. In the meta-analysis published by Modi et al, 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, particularly in patients with severe arch/ascending aortic 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 the right thoracotomy 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 purpose of this randomized blinded study is to prospectively evaluate major and minor neurologic events in patients undergoing right thoracotomy mitral valve surgery with retrograde perfusion and endoaortic balloon clamp (Endoreturn) or transthoracic clamp. Major neurologic events will be evaluate through standard neurologic evaluation; minor neurologic events will be evaluate through magnetic resonance assessment.

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.

Patients who have no contraindications will undergo cerebral MR before surgery as baseline assessment. Then, they will be randomized in one of the 2 groups.