Minimally invasive implantation of continuous flow left ventricular assist devices: the evolution of surgical techniques in a single centre experience

To evaluate the evolution of our surgical experience with the implantation of a continuous flow left ventricular assist device (LVAD), from the original full sternotomy approach to less invasive surgical strategies including mini-sternotomy and/or mini-thoracotomies

“Clinical Stability” and Propensity Score Matching in Cardiac Surgery: is the clinical evaluation of treatment efficacy algorithmdependent in small sample size settings?

Background: Propensity score matching represents one of the most popular techniques to deal with treatment allocation bias in observational studies. However, when the number of enrolled patients is very low, the creation of matched set of subjects may highly depend on the model used to estimate individual propensity scores, undermining the stability of consequential clinical findings. In this study, we investigate the potential issues related to the stability of the matched sets created by different propensity score models and we propose some diagnostic tools to evaluate them. Methods: Matched groups of patients were created using five different methods: Logistic Regression, Classification and Regression Trees, Bagging, Random Forest and Generalized Boosted Model. Differences between subjects in the matched sets were evaluated by comparing both pre-treatment covariates and propensity score distributions. We applied our proposal to a cardio-surgical observational study that aims to compare two different procedures of cardiac valve replacement. Results: Both baseline characteristics and propensity score distributions were systematically different across matched samples of patients created with different models used to estimate propensity score. The most relevant differences were observed for the matched set created by estimating individual propensity scores with Classification and Regression Trees algorithm. Conclusion: Clinical stability of matched samples created with different statistical methods should always be evaluated to ensure reliability of final estimates. This work opens the door for future investigations that fully assess the implications of this finding

Perceval Sutureless Pericardial Bioprosthesis valve: Clinico-pathological and Experimental Observations Bioprotesi pericardiche sutureless perceval: aspetti clinico-patologici ed osservazioni sperimentali

Background Excellent performances have been demonstrated in haemodynamic outcomes, safety, and versatility of use in the sutureless Perceval aortic valve (LivaNova, London, UK). However, several questions remain unanswered, especially regarding the effects of the “collapsing” during the reduction of the dimensions of the bioprostheses before implantation, and long-term durability: the design of this prosthesis closely resembles that of the Freedom Solo stentless prosthesis that was associated with a significant incidence of Structural Valve Deterioration (SVD) in different studies. Our research focused on understanding the impact of the “collapsing” in the pericardial structure and the modality of failure of this bioprosthesis when implanted in humans. Materials and methods To analyse the collapsing impact, 12 collapsed at 15 min (surgical procedure collapsing time), 60 and 180 min duration, and 4 uncollapsed (controls) LivaNova Perceval S prostheses were morphologically studied. Gross, histology and scanning electron microscopy (SEM) analysis were performed. Multiple sections of pericardial cusps have been stained with Hematoxylin-Eosin (HE), Azan Mallory, Elastic Van Gieson and Picrosirius Red, where a morphometrical analyses was performed by measuring the length of the collagen period. SVD was investigated in 33 Perceval bioprosthesis explanted in different European centres, from July 2007 to January 2017, participating to PIVOT TRIAL V10601, PIVOTAL TRAIL V10801, and CAVALIER TRIAL TPS001. In all the explants gross, histology (HE, Azan Mallory, Elastic van Gieson, Von Kossa, Gram stains), were performed. To assess a potential reduction of the effective orifice area (EOA) due to fibrous tissue overgrowth, the ratio expressed in percentage between the EOA area and the total area of the bioprosthesis on ventricular side was measured. Results Gross examination after collapsing and deployment revealed optimal cusp cooptation and absence of tears, perforation or folding. Moreover, prosthetic frame showed a preserved shape without distortion. Histology and SEM exhibited neither breaks nor differences in waviness periodicity of the fibrosa collagen fibers when compared to controls. Collagen wavelength periodicity measurement data did not reveal any statistically significant differences among the study groups (15 min collapse: 16.55±2.89 µm; 60 min collapse: 17.01±3.11 µm; 180 min collapse: 16.45±2.13 µm) and the un-collapsed controls (16.51±2.65 µm) and with unmounted pericardium (17.47±2.50 µm) (P=NS). Thirtythree bioprosthesis implanted in humans were examined. Endocarditis was diagnosed in 36% of all, which was similar to that reported for bioprosthesis valves, SVD by dystrophic calcification in 12% (only 4 cases), fibrous pannus overgrowth in 12% and paravalvular leak in 12%. Fibrous tissue overgrowth (on the valve and on the stent) was 61%, with and incidence of almost 83% in the bioprostheses with time in place more than one month. This alteration involved the valve as main pathology, causing mainly orifice stenosis, or was associated to other failure modalities, as endocarditis, calcific dystrophy, or paravalvular leak. Its distribution was in the valve, in valve and nitinol stent or climbing the sole stent, occluding sometimes the spaces of nitinol network. Conclusions Pre-implantation collapse and ballooning procedures do not affect the structural integrity of the collagen fibers of the pericardial cusp tissue of Perceval S sutureless valve bioprosthesis. In 4 cases early SVD by dystrophic calcification occurred at time in place of 5-6 years, questioning the efficacy of the anticalcification treatment of the pericardium. Progressive fibrous tissue overgrowth, invading the valve orifice, was the cause of the bioprosthesis stenosis even in absence of calcific dystrophy and did not spare the stent and nitinol network. Despite the evolution on new technologies, design and pericardial treatment, the fibrous tissue overgrowth remains a major concern of this new generation bioprostheses

Pulmonary embolism and LVAD: Is there compatibility?

A 41-year-old-male with diagnosis of dilated cardiomyopathy was referred to our hospital for heart failure, despite standard medical therapy, to evaluate indications for heart transplantation or mechanical cardiac support. Pre-Operative contrast computer tomography (CT) scan diagnosed pulmonary thrombosis of the left branch of the pulmonary artery. Treatment with low molecular weight heparin was established and the next day a thrombus-arteriectomy and Heartware (Heartware, Framingham, MA, USA) left ventricular assist device (LVAD) implantation were performed simultaneously. The patient was discharged home with oral anticoagulant and antiplatelet therapy, according to our center's VAD protocol. Currently, the patient has been assisted with the LVAD for the past 24 months. The CT scan confirmed the absence of pulmonary artery thrombosis. </jats:p