Novel Transcatheter Mitral Prosthesis Designed to Preserve Physiological Ventricular Flow Dynamics.

BACKGROUND: Current mitral bioprostheses are akin to the aortic valve and therefore abolish the left ventricular (LV) physiological vortex. We evaluated the hemodynamic performance and the effects on intraventricular flow dynamics (IFD) of a novel mitral bioprosthesis that presents an innovative design mimicking the native valve. METHODS: A D-shaped self-expandable stent-bovine pericardium monoleaflet valve was designed to provide physiological asymmetric intraventricular flow. Transapical implantation was consecutively performed in 12 juvenile sheep. Postimplant studies using Doppler echocardiography and IFD using echo particle imaging velocimetry were obtained immediately after the implantation and at 3 months to assess the hemodynamic performance of the prostheses. RESULTS: There were 3 deaths during follow-up, 1 due to valve misplacement because of poor imaging visualization and 2 not valve related. The mean transvalvular gradient and effective orifice area were 2.2 ± 1.2 mm Hg and 4.0 ± 1.1 cm2 after implantation and 3.3 ± 1.5 mm Hg and 3.5 ± 0.5 cm2 at 3 months, respectively. LV vortex dimension, orientation, and physiological anticlockwise rotation were preserved compared with preoperative normal LV flow pattern. One animal showed a moderate paravalvular leak, others mild or none. LV outflow tract obstruction, valve thrombosis, and hemolysis were not observed. CONCLUSIONS: Our preclinical in vivo results confirm the good hemodynamic performance of this new transcatheter bioprosthesis with preservation of the physiological IFD. Clinical studies are needed to document whether these characteristics will foster LV recovery and improve the clinical outcome of patients with mitral regurgitation.

The riddle of the right ventricle.

Right ventricular (RV) myxoma is a very rare finding. Its differential diagnosis includes cardiac thrombus, and its risk of life-threatening complications mandates early diagnosis followed by surgical resection. We report the case of a patient with an incidental RV mass and a difficult differential diagnosis. A 66-year-old woman, first assessed in neurosurgery due to a lumbar herniated disc, was referred to cardiology for examination before proceeding to surgery. She complained of dyspnea on exertion present for the last few months and reported no fainting or syncope. Clinical examination showed intermittent pulmonary systolic murmur. Transthoracic echocardiography revealed an oval-shaped sessile mobile mass (42∕18 mm) attached to the anterior RV wall. Computed tomography confirmed the presence of a RV mass with lower attenuation than the myocardium and extension towards the pulmonary trunk, without other abdominal or pulmonary masses that would suggest a thrombus. Cardiac magnetic resonance imaging described an ovoid mass (47∕16 mm) in the right ventricle, "clinging" to the apical trabeculae, swinging during the cardiac cycle, causing partial obstruction of the pulmonary valve during systole. The patient underwent surgical resection of the tumor. Macroscopic specimen showed a translucent polypoid mass with hemorrhagic areas. Microscopy confirmed the diagnosis of RV myxoma. The case illustrates the difficulty of establishing the correct etiological diagnosis of a cardiac mass, especially when located in the right ventricle. Multimodality imaging remains the cornerstone of noninvasive tissue characterization of cardiac masses, still requiring histopathological confirmation, particularly in the setting of conflicting imaging results.

Functional Regurgitation of Atrioventricular Valves and Atrial Fibrillation: An Elusive Pathophysiological Link Deserving Further Attention.

In patients with structurally normal atrioventricular valvular apparatus, functional regurgitation of the mitral or tricuspid valves has been attributed mainly to ventricular dilation and/or dysfunction, through a combination of annulus dilation and tethering of the valve leaflets. The occurrence of functional regurgitation of atrioventricular valves in patients with long-standing persistent atrial fibrillation and atrial dilation but normal ventricular size and function has received much less attention, and its peculiar mechanisms still remain to be understood. This distinct form of functional regurgitation (i.e., "atrial functional regurgitation") may require different treatment and interventional repair approaches than the classical functional regurgitation due to ventricular dilatation and dysfunction ("ventricular functional regurgitation"), and current guideline recommendations do not yet address this distinction. Clarifying the differences in the pathophysiology of atrial functional regurgitation and its management implications is of paramount importance. This review describes briefly the comparative anatomy of mitral and tricuspid apparatus and the pathophysiology and typical echocardiographic features of atrial functional regurgitation compared with ventricular functional regurgitation, as well as the added value of three-dimensional echocardiography as an essential imaging tool to clarify the mechanisms involved in its development.

Comparison of mitral annulus geometry between patients with ischemic and non-ischemic functional mitral regurgitation: implications for transcatheter mitral valve implantation.

BACKGROUND: Transcatheter mitral valve replacement (TMVR) is a new therapeutic option for high surgical risk patients with mitral regurgitation (MR). Mitral valve (MV) geometry quantification is of paramount importance for success of the procedure and transthoracic 3D echocardiography represents a useful screening tool. Accordingly, we sought to asses MV geometry in patients with functional MR (FMR) that would potentially benefit of TMVR, focusing on the comparison of mitral annulus (MA) geometry between patients with ischemic (IMR) and non ischemic mitral regurgitation (nIMR). METHODS: We retrospectively selected 94 patients with severe FMR: 41 (43,6%) with IMR and 53 (56,4%) with nIMR. 3D MA analysis was performed on dedicated transthoracic 3D data sets using a new, commercially-available software package in two moments of the cardiac cycle (early-diastole and mid-systole). We measured MA dimension and geometry parameters, left atrial and left ventricular volumes. RESULTS: Maximum (MA area 10.7 ± 2.5 cm2 vs 11.6 ± 2.7 cm2, p > 0.05) and the best fit plane MA area (9.9 ± 2.3 cm2 vs 10.7 ± 2.5 cm2, p > 0.05, respectively) were similar between IMR and nIMR. nIMR patients showed larger mid-systolic 3D area (9.8 ± 2.3 cm2 vs 10.8 ± 2.7 cm2, p < 0.05) and perimeter (11.2 ± 1.3 cm vs 11.8 ± 1.5 cm, p < 0.05) with longer and larger leaflets, and wider aorto-mitral angle (135 ± 10° vs 141 ± 11°, p < 0.05). Conversely, the area of MA at the best fit plane did not differ between IMR and nIMR patients (9 ± 1.1 cm2 vs 9.9 ± 1.5 cm2, p > 0.05). CONCLUSIONS: Patients with ischemic and non-ischemic etiology of FMR have similar maximum dimension, yet systolic differences between the two groups should be taken into account to tailor prosthesis's selection. TRIAL REGISTRATION: N.A.