A patient-specific adaptation of the Living Human Heart Model in application to pulmonary hypertension

The Living Heart Project aims to offer medical practitioners and researchers a full-heart electromechanical computational platform to explore and assess clinical cases pertaining to the left ventricle (LV), and the less addressed right ventricle (RV). It does not, however, provide an easy solution to applying this platform to patient-specific cases that account for a large variability among cases. We, therefore, present a solution to modify the Living Human Heart Model (LHHM) to obtain a patient-specific geometry using the thermal expansion method, with iteratively adjusted parameters that accurately simulate the case of a 72-year-old female patient suffering from secondary pulmonary hypertension caused by mitral valve regurgitation (MR). The patient underwent MV replacement and we simulate the heart from magnetic resonance imaging (MRI) images prior to surgery and 3 days following surgery. A mean pulmonary arterial pressure (mPAP) of approximately 64 mmHg was demonstrated before surgery, along with a severe lack of coaptation of the mitral valve. Reduced function of the cardiac chambers is exhibited in the reduced ejection fraction (EF). We also demonstrate left-side failure, an increase in Global Longitudinal Strain (GLS) and the location of maximum cardiac wall stress located at the mid anterolateral wall of the RV where dilation traditionally manifests. Comparison of patient geometry pre-operation and post-surgery showed a change in shape of the Tricuspid Annulus (TA) in systole. A rigid constraint across the TA was used to simulate an annuloplasty ring, and an increase in ring-widening forces was observed post-operation, with a significant reduction in forces being present in contractile forces on the ring. This model led us to conclude that the patient will likely develop TV annular dilatation and subsequent regurgitation in the absence of intervention. We verify the use of the LHHM for assessing potential remodeling and subclinical RV dysfunction, and subsequent intervention and attenuation of pulmonary hypertension by a mitral valve replacement. The lack of personalization and wide variability have remained a significant reason for the slow adoption rate of computational tools among medical practitioners, but we see this work as a substantial addition to computational cardiology, and foresee a closer integration of such technology to mainstream application among members of the medical community

Patient-specific finite element analysis of heart failure and the impact of surgical intervention in pulmonary hypertension secondary to mitral valve disease

Pulmonary hypertension (PH), a chronic and complex medical condition affecting 1% of the global population, requires clinical evaluation of right ventricular maladaptation patterns under various conditions. A particular challenge for clinicians is a proper quantitative assessment of the right ventricle (RV) owing to its intimate coupling to the left ventricle (LV). We, thus, proposed a patient-specific computational approach to simulate PH caused by left heart disease and its main adverse functional and structural effects on the whole heart. Information obtained from both prospective and retrospective studies of two patients with severe PH, a 72-year-old female and a 61-year-old male, is used to present patient-specific versions of the Living Heart Human Model (LHHM) for the pre-operative and post-operative cardiac surgery. Our findings suggest that before mitral and tricuspid valve repair, the patients were at risk of right ventricular dilatation which may progress to right ventricular failure secondary to their mitral valve disease and left ventricular dysfunction. Our analysis provides detailed evidence that mitral valve replacement and subsequent chamber pressure unloading are associated with a significant decrease in failure risk post-operatively in the context of pulmonary hypertension. In particular, right-sided strain markers, such as tricuspid annular plane systolic excursion (TAPSE) and circumferential and longitudinal strains, indicate a transition from a range representative of disease to within typical values after surgery. Furthermore, the wall stresses across the RV and the interventricular septum showed a notable decrease during the systolic phase after surgery, lessening the drive for further RV maladaptation and significantly reducing the risk of RV failure