Ramifications of Vorticity on Aggregation and Activation of Platelets in Bi-Leaflet Mechanical Heart Valve: Fluid-Structure-Interaction Study.

Bileaflet mechanical heart valves (BMHV) are widely implanted to replace diseased heart valves. Despite many improvements in design, these valves still suffer from various complications, such as valve dysfunction, tissue overgrowth, hemolysis, and thromboembolism. Thrombosis and thromboembolism are believed to be initiated by platelet activation due to contact with foreign surfaces and nonphysiological flow patterns. The implantation of the valve causes nonphysiological patterns of vortex shedding behind the leaflets. This study signifies the importance of vorticity in platelet activation and aggregation in BMHV implants. A two-phase model with the first Eulerian phase for blood and the second discrete phase for platelets is used here. The generalized cross model of viscosity has been used to simulate the non-Newtonian viscosity of blood. A fluid-structure-interaction model has been used to simulate the motion of leaflets. This study has also estimated the platelet activation state (PAS), which is the mathematical estimation of the degree of activation of platelets due to flow-induced shear stresses that cause thrombus formation. The regions in the fluid domain with a higher vorticity field have been found to contain platelets with relatively higher PAS than regions with relatively lower vorticity fields. Also, this study has quantitatively reported the effect of vorticity on platelet aggregation. Platelet densities in fluid areas with higher vorticity are higher than densities in fluid areas with lower vorticity, indicating that highly activated platelets aggregate in areas with stronger vorticity.

Clinical outcomes and hemodynamic performance of Dafodil™ aortic and mitral pericardial bioprosthesis: 1-year results from Dafodil-1 first-in-human trial.

BACKGROUND: Bioprosthesis has been increasingly implanted for the treatment of transvalvular disease across the world. A new Dafodil™ pericardial bioprosthesis (Meril Life Sciences Pvt. Ltd., India) recently approved by Conformité Européenne (CE) is a tri-leaflet, stented, bovine valve. The purpose of Dafodil-1 first-in-human trial was to evaluate clinical safety and performance (including hemodynamic parameters) of the Dafodil pericardial bioprosthesis in patients who underwent aortic or mitral valve replacement. METHODS: This prospective, multicenter clinical trial enrolled 60 patients (Aortic: 30 patients; Mitral: 30 patients) from seven sites across India. Safety endpoints were early (≤30 days) and late (> 30 days) mortality and valve-related morbidity. The performance endpoints were hemodynamic performance, improvement in NYHA functional class, and change in the quality of life using SF-12v1 health survey. RESULTS: From July 2017 to July 2018, 60 patients underwent implantation of the Dafodil pericardial bioprosthesis. Post-operatively, NYHA functional class significantly improved in all the patients (Aortic: 90% NYHA class-I and 10% NYHA class-II; Mitral: 96.55% NYHA class-I and 3.45% NYHA class-II; P < 0.001). There was no death in aortic valve replacement patients till 12-month. In mitral valve replacement patients, early mortalities occurred in three patients, and late mortality occurred in one patient; none of these were valve-related. Freedom from all-cause mortality reported was 93.33% at 12-month. Mean aortic pressure gradient decreased from 52.71 ± 24.47 mmHg [with 0.89 ± 0.70 cm2 effective orifice area (EOA)] pre-operatively to 14.49 ± 6.58 mmHg (EOA: 1.85 ± 0.27 cm2) at 12-month. Overall, the mitral mean pressure gradient and EOA were 4.41 ± 1.69 mmHg and 2.67 ± 0.48 cm2, respectively, at 12-month. Significant improvement (P < 0.05) in the patients' quality of life was reported at all follow-ups. CONCLUSIONS: The clinical safety and performance of the Dafodil pericardial bioprosthesis were favourable at 12-month. Moreover, a study with a larger patient population and longer follow-up is warranted to further assess the device. TRIAL REGISTRATION: Dafodil-1 trial has been prospectively registered on 10/07/2017 under Clinical Trial Registry-India (http://www.ctri.nic.in). (Registration number: CTRI/2017/07/009008).

Right paracardiac mass due to organized pericardial hematoma around retained epicardial pacing wires following aortic valve replacement.

The use of temporary epicardial pacing wires during cardiac surgery is a routine procedure and has been associated with low morbidity. We describe a rare case of right paracardiac mass due to organized pericardial hematoma with right atrial compression around the epicardial pacing wires left in-situ, presenting three months following aortic valve replacement surgery. The case highlights the fact that such delayed complications can rarely occur around retained epicardial pacing wires following open heart surgery especially in patients on oral anticoagulants. The clinician should be alert to such an occurrence and during follow-up echocardiography always pay attention not only to the valve and ventricular function, but also to the pericardial and extra-pericardial space.

Chemoradiotherapy for locally advanced head and neck cancer: 10-year follow-up of the UK Head and Neck (UKHAN1) trial.

BACKGROUND: Between 1990 and 2000, we examined the effect of timing of non-platinum chemotherapy when combined with radiotherapy. We aimed to determine whether giving chemotherapy concurrently with radiotherapy or as maintenance therapy, or both, affected clinical outcome. Here we report survival and recurrence after 10 years of follow-up. METHODS: Between Jan 15, 1990, and June 20, 2000, 966 patients were recruited from 34 centres in the UK and two centres from Malta and Turkey. Patients with locally advanced head and neck cancer, and who had not previously undergone surgery, were randomly assigned to one of four groups in a 3:2:2:2 ratio, stratified by centre and chemotherapy regimen: radical radiotherapy alone (n=233); radiotherapy with two courses of chemotherapy given simultaneously on days 1 and 14 of radiotherapy (SIM alone; n=166); or 14 and 28 days after completing radiotherapy (SUB alone, n=160); or both (SIM+SUB; n=154). Chemotherapy was either methotrexate alone, or vincristine, bleomycin, methotrexate, and fluorouracil. Patients who had previously undergone radical surgery to remove their tumour were only randomised to radiotherapy alone (n=135) or SIM alone (n=118), in a 3:2 ratio. The primary endpoints were overall survival (from randomisation), and event-free survival (EFS; recurrence, new tumour, or death; whichever occurred first) among patients who were disease-free 6 months after randomisation. Analyses were by intention to treat. This trial is registered at www.Clinicaltrials.gov, number NCT00002476. FINDINGS: All 966 patients were included in the analyses. Among patients who did not undergo surgery, the median overall survival was 2.6 years (99% CI 1.9-4.2) in the radiotherapy alone group, 4.7 (2.6-7.8) years in the SIM alone group, 2.3 (1.6-3.5) years in the SUB alone group, and 2.7 (1.6-4.7) years in the SIM+SUB group (p=0.10). The corresponding median EFS were 1.0 (0.7-1.4), 2.2 (1.1-6.0), 1.0 (0.6-1.5), and 1.0 (0.6-2.0) years (p=0.005), respectively. For every 100 patients given SIM alone, there are 11 fewer EFS events (99% CI 1-21), compared with 100 given radiotherapy, 10 years after treatment. Among the patients who had previously undergone surgery, median overall survival was 5.0 (99% CI 1.8-8.0) and 4.6 (2.2-7.6) years in the radiotherapy alone and SIM alone groups (p=0.70), respectively, with corresponding median EFS of 3.7 (99% CI 1.1-5.9) and 3.0 (1.2-5.6) years (p=0.85), respectively. The percentage of patients who had a significant toxicity during treatment were: 11% (radiotherapy alone, n=25), 28% (SIM alone, n=47), 12% (SUB alone, n=19), and 36% (SIM+SUB, n=55) among patients without previous surgery; and 9% (radiotherapy alone, n=12) and 20% (SIM alone, n=24) among those who had undergone previous surgery. The most common toxicity during treatment was mucositis. The percentage of patients who had a significant toxicity at least 6 months after randomisation were: 6% (radiotherapy alone, n=13), 6% (SIM alone, n=10), 4% (SUB alone, n=7), and 6% (SIM+SUB, n=9) among patients who had no previous surgery; and 7% (radiotherapy alone, n=10) and 11% (SIM alone, n=13) among those who had undergone previous surgery. The most common toxicity 6 months after treatment was xerostomia, but this occurred in 3% or less of patients in each group. INTERPRETATION: Concurrent non-platinum chemoradiotherapy reduces recurrences, new tumours, and deaths in patients who have not undergone previous surgery, even 10 years after starting treatment. Chemotherapy given after radiotherapy (with or without concurrent chemotherapy) is ineffective. Patients who have undergone previous surgery for head and neck cancer do not benefit from non-platinum chemotherapy. FUNDING: Cancer Research UK, with support from University College London and University College London Hospital Comprehensive Biomedical Research Centre.

Assessment of right ventricular diastolic function: does it predict post-operative course in tetralogy of Fallot.

BACKGROUND: In some cases of tetralogy of Fallot the post-operative course is characterized by episodes of low cardiac output, elevated central filling pressures and prolonged ventilation and inotropic support. This may be due to impaired diastolic function of the right ventricle despite preservation of biventricular systolic function. METHODS AND RESULTS: Sixty-four consecutive patients (mean age 7.06+/-4.9 years) undergoing repair of tetralogy of Fallot were prospectively studied to assess right ventricular diastolic function. 'Restrictive physiology' was defined as presence of laminar antegrade diastolic pulmonary artery flow (A wave) throughout the respiratory cycle, which was coincident with atrial systole. Right ventricle restriction was present in 45/64 (70%, Group 1) patients and absent in 19/64 (30%, Group 2) patients. There was a marked inspiratory augmentation of the pulmonary artery A wave velocity, flow integral and duration. Transtricuspid flow revealed significantly lower peak E velocity, lower E/A ratio, shorter E deceleration time and higher A velocity time integral in those with right ventricular restriction. Biventricular systolic function and transmitral flow were normal in all patients. Those with restrictive physiology had significantly longer mean inotrope support duration, longer ventilation and chest drainage times. Correspondingly, the mean intensive care unit stay (56.7+/-9.3 v. 34.7+/-5.38 hours, p<0.01) and mean hospital discharge time (9.3+/-2.3 v. 6.2+/-0.5 days, p <0.001) was also significantly longer in group 1. CONCLUSIONS: Right ventricular restriction (as seen by laminar antegrade diastolic pulmonary artery flow throughout the respiratory cycle) exists in a significant subset of patients with tetralogy of Fallot following operative repair. Following surgery, such patients have higher inotropic requirement, longer ventilation times and longer hospital stay.