Entity

Time filter

Source Type

Milano, Italy

Tasca G.,Cardiac Surgery Unit | Tasca G.,Polytechnic of Milan | Vismara R.,Polytechnic of Milan | Fiore G.B.,Polytechnic of Milan | And 9 more authors.
European Journal of Cardio-thoracic Surgery | Year: 2014

OBJECTIVES: Small-sized aortic bioprostheses may cause high postoperative gradients. In clinical practice, it is difficult to compare bioprostheses from different manufactures, owing to the discrepancy between the true size and the nominal size of the prosthesis and the inter-patient variability in aortic root characteristics. In vitro studies provide accurate data, and using a system in which it is possible to implant bioprostheses in a true aortic root should enable a fair comparison to be made. The present study compared the four most widely used pericardial stented bioprostheses from different manufacturers surgically implanted in small annulus, to detect any differences in their fluid-dynamic performance. METHODS: The four types of bioprostheses, each implanted in a randomized sequence in eight porcine aortic roots, with a native annulus of 2.1 cm, were tested in a mock loop at 65 ml of stroke volume by calculating hydrodynamic parameters, namely mean pressure drop and effective orifice area, performance index, valve resistance and % of energy loss. The prostheses that fitted the aortic root after sizing were as follows: a Magna Ease 21, a Trifecta 21, a Soprano-Armonia 20 and a Mitroflow 23. RESULTS: Effective orifice areas were 1.57 ± 0.2, 1.77 ± 0.2, 2.3 ± 0.3 and 1.75 ± 0.2 cm2 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The mean gradients were 13.2 ± 3, 10.2 ± 3, 6.1 ± 2 and 9.6 ± 2 mmHg (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The performance indices were 0.50 ± 0.06, 0.63 ± 0.08, 0.89 ± 0.13 and 0.56 ± 0.07 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The valve resistance, expressed in (dyn*s/cm5), was 69 ± 16, 55 ± 13, 33 ± 10 and 51 ± 11 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The percent of energy loss was 13.5 ± 0.5, 10.7 ± 2.5, 6.6 ± 1.6, 10.9 ± 1.8 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. CONCLUSION: Our study combined the fluid-dynamic reproducibility of the in vitro study with, by using porcine aortic roots, the specificity of surgery. The results confirmed that bioprostheses are inherently obstructive compared with the native aortic valve and showed that bioprostheses with the pericardium outside the stent are more efficient. © The Author 2014. Source


Tasca G.,Cardiac Surgery Unit | Tasca G.,Polytechnic of Milan | Vismara R.,Polytechnic of Milan | Fiore G.B.,Polytechnic of Milan | And 6 more authors.
Journal of Thoracic and Cardiovascular Surgery | Year: 2015

Background The in vivo hemodynamic performance of a bioprosthesis implanted in an aortic position is affected by the characteristics of the prosthesis and the sizing strategy adopted. Recently, it has been hypothesized that the type of suture used to implant the prosthesis might influence hemodynamics. Methods Bioprostheses with labeled sizes of 19 mm and 21 mm were implanted in 2 groups of 5 porcine aortic roots, with native annuli of 19 mm and 21 mm, by means of 2 different suture techniques: simple interrupted and noneverting mattress with pledgets. The aortic roots were tested in an in vitro mock loop. The stroke volume imposed by the mock loop was set at 40 mL, and was increased by steps of 15 mL until a stroke volume of 100 mL was attained. Main fluid-dynamic parameters were analyzed. Results At each level of stroke volume, ie, 40 mL, 55 mL, 70 mL, 85 mL, and 100 mL, the mean and peak pressure drops were significantly greater with the noneverting mattress suture with pledgets than with the simple interrupted suture. The effective orifice area behaved accordingly, being significantly smaller in the former case. Conclusions Our data show that the type of suture technique can influence bioprosthesis performance and that it is reasonable to assume that this is especially true in small annuli (≤21 mm). Thus, to optimize prosthesis performance and reduce the incidence of patient-prosthesis mismatch, the role of the suture technique should not be disregarded. © 2015 The American Association for Thoracic Surgery. Source


Votta E.,Polytechnic of Milan | Paroni L.,Polytechnic of Milan | Conti C.A.,Polytechnic of Milan | Pelosi A.,Polytechnic of Milan | And 7 more authors.
Annals of Biomedical Engineering | Year: 2012

Recently, the neo-chordae technique (NCT) was proposed to stabilize the surgical correction of isolated aortic valve (AV) prolapse. Neo-chordae are inserted into the corrected leaflet to drive its closure by minimal tensions and prevent relapses. In a previous in vitro study we analysed the NCT effects on healthy aortic roots (ARs). Here we extend that analysis via finite element models (FEMs). After successfully replicating the experimental conditions for validation purposes, we modified our AR FEM, obtaining a continent AV with minor isolated prolapse, thus representing a realistic clinical scenario. We then simulated the NCT, and systematically assessed the acute effects of changing neo-chordae length, opening angle, asymmetry and insertion on the aorta. In the baseline configuration the NCT restored physiological AV dynamics and coaptation, without inducing abnormal leaflet stresses. This outcome was notably sensitive only to neo-chordae length, suggesting that the NCT is a potentially easy-to-standardize technique. However, this parameter is crucial: major shortenings (6 mm) prevent coaptation and increase leaflet stresses by 359 kPa, beyond the yield limit. Minor shortenings (2-4 mm) only induce a negligible stress increase and mild leaflet tethering, which however may hamper the long-term surgical outcome. © 2011 Biomedical Engineering Society. Source


Vismara R.,Polytechnic of Milan | Leopaldi A.M.,Life Tec Group | Piola M.,Polytechnic of Milan | Asselta C.,Polytechnic of Milan | And 8 more authors.
Medical Engineering and Physics | Year: 2016

Recent approaches to the in vitro experimental study of cardiac fluid mechanics involve the use of whole biological structures to investigate in the lab novel therapeutic approaches for the treatment of heart pathologies. To enhance reliability and repeatability, the influence of the actuation strategy of the experimental apparatuses on the biomechanics of biological structures needs to be assessed.Using echography and intracardiac high-speed imaging, we compared the mitral valve (MV) anatomo-functional features (coaptation areas/lengths, papillary muscles-valvular plane distances) in two passive-beating-heart mock loops with internal (IPML) or external (EPML) pressurization of the ventricular chamber.Both apparatuses showed fluid dynamic conditions that closely resembled the physiology. The MVs analyzed in the EPML presented coaptation areas and lengths that were systematically higher, and exhibited greater variability from early-to peak-systole, as compared to those in the IPML. Moreover, in the EPML, the MV leaflets exhibited a convexity with high curvature toward the atrium. With the IPML, MV coaptation lengths ranged similar to available clinical data and the papillary muscles-valve plane distances were more stable throughout systole.In conclusion, both the apparatuses allow for reproducing in vitro the left heart hemodynamics, in terms of flow rates and pressures, with proper mitral valve continence. Results suggest that the IPML is more suitable for replicating the physiological MV functioning, while the EPML may have more potential as a model for the study of MV pathologies. © 2016 IPEM. Source


Vismara R.,Polytechnic of Milan | Fiore G.B.,Polytechnic of Milan | Mangini A.,Forcardiolab | Mangini A.,University of Milan | And 6 more authors.
ASAIO Journal | Year: 2010

The aortic root functional unit (ARFU) is a complex structure whose functions are strictly dependent on the biomechanical interaction among each of its anatomically defined elements. The classical approach to the in vitro study of aortic hydrodynamics does not take this complexity into account. We propose a novel methodology based on the possibility to house whole natural ARFU samples in a purposely designed pulsatile mock loop, allowing for aortic surgery simulation. To point out the usability and potentialities of the device, the mock loop was tested with untreated porcine ARFU samples and with one ARFU prosthesized with a state-of-the-art bioprosthesis. The sample holder design was proved to allow the clinician to house and treat the ARFU sample in the mock loop with easiness and repeatability. The valve leakage with the prosthesized ARFU was comparable with literature data, and Effective orifice areas were consistent with the constructor's data. In contrast, the recorded pressure drops exceeded the data from the manufacturer and were quite aligned with in vivo postop echo-Doppler data acquired in implant recipients. This result suggests that our apparatus and methodology provide a way to investigate aortic hydrodynamic phenomena that resemble in a close way to those taking place in the final recipients' circulation. Copyright © American Society of Artificial Internet Organs. Source

Discover hidden collaborations