Cesare Scardulla

Difference in hemodynamic and wall stress of ascending thoracic aortic aneurysms with bicuspid and tricuspid aortic valve

The aortic dissection (AoD) of an ascending thoracic aortic aneurysm (ATAA) initiates when the hemodynamic loads exerted on the aneurysmal wall overcome the adhesive forces holding the elastic layers together. Parallel coupled, two-way fluid-structure interaction (FSI) analyses were performed on patient-specific ATAAs obtained from patients with either bicuspid aortic valve (BAV) or tricuspid aortic valve (TAV) to evaluate hemodynamic predictors and wall stresses imparting aneurysm enlargement and AoD. Results showed a left-handed circumferential flow with slower-moving helical pattern in the aneurysms center for BAV ATAAs whereas a slight deviation of the blood flow toward the anterolateral region of the ascending aorta was observed for TAV ATAAs. Blood pressure and wall shear stress were found key hemodynamic predictors of aneurysm dilatation, and their dissimilarities are likely associated to the morphological anatomy of the aortic valve. We also observed discontinues, wall stresses on aneurysmal aorta, which was modeled as a composite with two elastic layers (i.e., inhomogeneity of vessel structural organization). This stress distribution was caused by differences on elastic material properties of aortic layers. Wall stress distribution suggests AoD just above sinotubular junction. Moreover, abnormal flow and lower elastic material properties that are likely intrinsic in BAV individuals render the aneurysm susceptible to the initiation of AoD.

Prediction of right ventricular failure after ventricular assist device implant: systematic review and meta-analysis of observational studies

Right ventricular failure (RVF) after left ventricular assist device (LVAD) implantation is associated with increased morbidity and mortality, but the identification of LVAD candidates at risk for RVF remains challenging. We undertook a systematic review and meta‐analysis of observational studies of risk factors associated with RVF after LVAD implant. Thirty‐six studies published between 1 January 1995 and 30 April 2015, comprising 995 RVF patients out of a pooled final population of 4428 patients, were identified. Meta‐analysed prevalence of post‐LVAD RVF was 35%. A need for mechanical ventilation [odds ratio (OR) 2.99], or continuous renal replacement therapy (CRRT; OR 4.61, area under the curve 0.78, specificity 0.91) were the clinical variables with the highest effect size (ES) in predicting RVF. International normalized ratio [INR; standardized mean difference (SMD) 0.49] and N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) (SMD 0.52) were the biochemical markers that best discriminated between RVF and No‐RVF populations, though NT‐proBNP was highly heterogeneous. Right ventricular stroke work index (RVSWI) and central venous pressure (CVP) (SMD −0.58 and 0.47, respectively) were the haemodynamic measures with the highest ES in identifying patients at risk of post‐LVAD RVF; CVP was particularly useful in risk stratifying patients undergoing continuous‐flow LVAD implant (SMD 0.59, P < 0.001, I2 = 20.9%). Finally, pre‐implant moderate to severe right ventricular (RV) dysfunction, as assessed qualitatively (OR 2.82), or a greater RV/LV diameter ratio (SMD 0.51) were the standard echocardiographic measurements with the highest ES in comparing RVF with No‐RVF patients. Longitudinal systolic strain of the RV free wall had the highest ES (SMD 0.73) but also the greatest heterogeneity (I2 = 74%) and was thus only marginally significant (P = 0.05). Patients on ventilatory support or CRRT are at high risk for post‐LVAD RVF, similarly to patients with slightly increased INR, high NT‐proBNP or leukocytosis. High CVP, low RVSWI, an enlarged right ventricle with concomitant low RV strain also identify patients at higher risk.

Can multiple previous treatment-requiring rejections affect biventricular myocardial function in heart transplant recipients? A two-dimensional speckle-tracking study

a Cardiology Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS— ISMETT (IstitutoMediterraneo per i Trapianti e Terapie ad alta Specializzazione), Via Tricomi 5, 90127 Palermo, Italy b Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, IRCCS— ISMETT (IstitutoMediterraneo per i Trapianti e Terapie ad alta Specializzazione), Via Tricomi 5, 90127 Palermo, Italy c Research Office, IRCCS — ISMETT (Istituto Mediterraneo per i Trapianti e Terapie ad alta Specializzazione), Via Tricomi 5, 90127 Palermo, Italy d University of Liege Hospital, GIGA Cardiovascular Sciences, Department of Cardiology, Heart Valve Clinic, CHU Sart Tilman, Liege, Belgium

Circulatory response to volume expansion and transjugular intrahepatic portosystemic shunt in refractory ascites: Relationship with diastolic dysfunction

BACKGROUND Cirrhotic cardiomyopathy may lead to heart failure in stressful circumstances, such as after transjugular intrahepatic portosystemic shunt (TIPS) placement. AIM To examine whether acute volume expansion predicts haemodynamic changes after TIPS and elicits signs of impending heart failure. METHODS We prospectively evaluated refractory ascites patients (group A) and compensated cirrhotics (group B), who underwent echocardiography, NT-proBNP measurement, and heart catheterization before and after volume load; group A repeated measurements after TIPS. RESULTS 15 patients in group A (80% male; 54±12.4 years) and 8 in group B (100% male; 56±6.2 years) were enrolled. Echocardiography disclosed diastolic dysfunction in 30% and 12.5%, respectively. In group A, volume load and TIPS induced a significant increase in right atrial, mean pulmonary, capillary wedge pressure and cardiac index, and a decrease in systemic vascular resistance (respectively, 4.7±2.8 vs. 9.9±3.6 mmHg; 13.3±3.5 vs. 21.9±5.9 mmHg; 8.3±3.4 vs. 15.4±4.7 mmHg; 3.7±0.7 vs. 4.6±11 t/min/m2; 961±278 vs. 767±285 dynscm(-5); and 10.1±3.3 vs. 14.2±3.4 mmHg; 17.5±4 vs. 25.2±4.2 mmHg; 12.3±4 vs. 19.3±3.4 mmHg; 3.4±0.8 vs. 4.5±0.91l t/min/m2; 779±62 vs. 596±199 dynscm(-5), p<0.001 for all pairs). At 24h, cardiopulmonary pressures returned towards baseline. CONCLUSIONS Acute volume expansion predicted haemodynamic changes immediately after TIPS. All patients had adequate haemodynamic adaptation to TIPS; none developed signs of heart failure.

Evaluation of ventricular wall stress and cardiac function in patients with dilated cardiomyopathy

Dilated cardiomyopathy is a heart disease characterized by both left ventricular dilatation and left ventricular systolic dysfunction, leading to cardiac remodeling and ultimately heart failure. We aimed to investigate the effect of dilated cardiomyopathy on the pump performance and myocardial wall mechanics using patient-specific finite element analysis. Results evinced pronounced end-systolic wall stress on left ventricular wall of patients with dilated cardiomyopathy as compared to that of normal hearts. In dilated cardiomyopathy, both end-diastolic and end-systolic pressure–volume relationships of left ventricle and right ventricle were shifted to the right compared to controls, suggesting reduced myocardial contractility. We hereby propose that finite element analysis represents a useful tool to assess the myocardial wall stress and cardiac work, which are responsible for progressive left ventricular deterioration and poor clinical course.

Diastolic dysfunction diagnosed by tissue Doppler imaging in cirrhotic patients: Prevalence and its possible relationship with clinical outcome☆

BACKGROUND Cirrhotic cardiomyopathy has been characterized by impaired contractile response to stress and/or altered diastolic relaxation, with electrophysiological abnormalities in the absence of known cardiac disease. However, the clinical significance of diastolic dysfunction (DDF) in cirrhotic patients has not been clarified. METHODS We studied 84 cirrhotic patients with normal systolic function to evaluate the prevalence of DDF using tissue Doppler imaging, and to investigate the possible correlation of DDF with outcomes (hospitalization, death) and with the specific causes of death. RESULTS The mean follow-up was 10±8months. DDF was diagnosed in 22 patients (26.2%). Patients with DDF more frequently had ascites (90.9% vs. 64.5 %; p=0.026), lower levels of albumin (OR: 5.39; p=0.004), higher NT-proBNP levels, and longer QTc interval (464±23ms vs. 452±30ms; p=0.039). At follow-up, patients with DDF did not have a higher incidence of adverse events in terms of hospitalization and death. CONCLUSIONS The presence of diastolic dysfunction has not been found to be clearly associated with outcome, and prognosis has been determined primarily by the severity of liver disease.

An In Vitro Phantom Study on the Role of the Bird-Beak Configuration in Endograft Infolding in the Aortic Arch

Purpose: To assess endograft infolding for excessive bird-beak configurations in the aortic arch in relation to hemodynamic variables by quantifying device displacement and rotation of oversized stent-grafts deployed in a phantom model. Methods: A patient-specific, compliant, phantom pulsatile flow model was reconstructed from a patient who presented with collapse of a Gore TAG thoracic endoprosthesis. Device infolding was measured under different flow and pressure conditions for 3 protrusion extensions (13, 19, and 24 mm) of the bird-beak configuration resulting from 2 TAG endografts with oversizing of 11% and 45%, respectively. Results: The bird-beak configuration with the greatest protrusion extension exhibited the maximum TAG device displacement (1.66 mm), while the lowest protrusion extension configuration led to the minimum amount of both displacement and rotation parameters (0.25 mm and 0.6°, respectively). A positive relationship was found between the infolding parameters and the flow circulating in the aorta and left subclavian artery. Similarly, TAG device displacement was positively and significantly (p<0.05) correlated with the pulse pressure for all bird-beak configurations and device sizes. However, no collapse was observed under chronic perfusion testing maintained for 30 days and pulse pressure of 100 mm Hg. Conclusion: These findings suggest that endograft infolding depends primarily on the amount of aortic pulsatility and flow rate and that physiological flows do not necessarily engender hemodynamic loads on the proximal bird-beak segment sufficient to cause TAG collapse. Hemodynamic variables may allow for identification of patients at high risk of endograft infolding and help guide preventive intervention to avert its occurrence.

Mechanics of pericardial effusion: a simulation study.

Pericardial effusion is a pathological accumulation of fluid within pericardial cavity, which may compress heart chambers with hemodynamic impairment. We sought to determine the mechanics underlying the physiology of the hemodynamic impairment due to pericardial effusion using patient-specific computational modeling. Computational models of left ventricle and right ventricle were based on magnetic resonance images obtained from patients with pericardial effusion and controls. Myocardial material parameters were adjusted, so that volumes of ventricular chambers and pericardial effusion agreed with magnetic resonance imaging data. End-diastolic and end-systolic pressure–volume relationships as well as stroke volume were determined to evaluate impaired cardiac function of biventricular model. Distributions of myocardial fiber stresses and their regional variation along left ventricular wall were compared between patient groups. Both end-diastolic and end-systolic pressure–volume relationships shifted to the left for patients with pericardial effusion, with right ventricle diastolic filling particularly restricted. Left ventricle function as estimated by Starling curve was reduced by pericardial effusion. End-systolic fiber stress of left ventricle was significantly reduced as compared to that found for healthy patients. Myocardial stress was found increased at interventricular septum when compared to that exerted at lateral wall of left ventricle. Right ventricular myocardial stress was reduced as a consequence of the pressure equalization between right ventricle and pericardial effusion. Diastolic right ventricle collapse in patients with pericardial effusion is related to higher myocardial fiber stress on interventricular septum and to an extensible pericardium reducing motion of ventricular chambers, with right ventricle particularly restrained. These findings likely portend progression of pericardial effusion to cardiac tamponade.

Biomechanical implications of excessive endograft protrusion into the aortic arch after thoracic endovascular repair

Endografts placed in the aorta for thoracic endovascular aortic repair (TEVAR) may determine malappositioning to the lesser curvature of the aortic wall, thus resulting in a devastating complication known as endograft collapse. This premature device failure commonly occurs in young individuals after TEVAR for traumatic aortic injuries as a result of applications outside the physical conditions for which the endograft was designed. In this study, an experimentally-calibrated fluid-structure interaction (FSI) model was developed to assess the hemodynamic and stress/strain distributions acting on the excessive protrusion extension (PE) of endografts deployed in four young patients underwent TEVAR. Endograft infolding was experimentally measured for different hemodynamic scenarios by perfusion testing and then used to numerically calibrate the mechanical behavior of endograft PE. Results evinced that the extent of endograft can severely alter the hemodynamic and structural loads exerted on the endograft PE. Specifically, PE determined a physiological aortic coarctation into the aortic arch characterized by a helical flow in the distal descending aorta. High device displacement and transmural pressure across the stent-graft wall were found for a PE longer than 21 mm. Finally, marked intramural stress and principal strain distributions on the protruded segment of the endograft wall may suggest failure due to material fatigue. These critical parameters may contribute to the endograft collapse observed clinically and can be used to design new devices more suitable for young individuals to be treated with an endoprosthesis for TEVAR of blunt traumatic aortic injuries.

Patients with bicuspid aortic valve are likely to receive an aortic valve prosthesis during prophylactic resection of their ascending aortic aneurysm

☆ All authors take responsibility for all aspects of the reli the data presented and their discussed interpretation. ⁎ Corresponding author at: Cardiac Surgery and Department for the Treatment and Study of Cardiothora Transplantation, Mediterranean Institute for Transplanta Therapies (ISMETT), Via Tricomi 5, 90127 Palermo, Italy. E-mail address: giuseppe.raffa78@gmail.com (G.M. Ra 1 Equal contribution as first author.