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Biomedical subjects

O Alfieri

Publications and source records attributed to O Alfieri.

At least 19 recordsLinked to original sources
PubMed2004

Flow dynamics of the St Jude Medical Symmetry aortic connector vein graft anastomosis do not contribute to the risk of acute thrombosis.

BACKGROUND: The efficacy of the St Jude Medical Symmetry aortic connector (St Jude Medical, Inc, St Paul, Minn) for coronary artery bypass is currently debated. Potential drawbacks are the biocompatibility of the endoluminal device, the need for graft manipulation during the procedure, and the 90 degrees offset of the vein graft from the ascending aorta, which may induce graft kinking and abnormal fluid dynamics. In this article, a computational approach was designed to investigate the fluid dynamics pattern at the proximal graft. METHODS: Four models of hand-sewn anastomoses and two models of automated anastomoses were constructed; a finite volume technique was used to simulate realistic graft fluid dynamics, including aortic compliance and proper aortic and graft flow rates. The anastomosis geometry performance was analyzed by calculating time-averaged wall shear stress and the oscillating shear index at the toe and heel regions of the proximal graft. RESULTS: Time-averaged wall shear stress was significantly lower in the hand-sewn anastomosis models than in the two models that simulated the use of the aortic connector (0.38 +/- 0.07 Pa vs 1.32 +/- 0.4 Pa). Higher oscillating shear index values were calculated in the hand-sewn anastomosis models (0.15 +/- 0.02 Pa vs 0.06 +/- 0.02 Pa). CONCLUSIONS: Automated anastomosis geometry is associated with less critical fluid dynamics than with conventional hand-sewn anastomosis: the shape of the proximal graft induces more physiological wall shear stresses and less oscillating flow, suggesting a lower risk of atherosclerotic plaque and intimal hyperplasia as compared with conventional anastomosis geometry. Therefore, the reported early thrombosis and late failure of the St Jude Medical aortic connector anastomoses are not related to unfavorable fluid dynamics.

Acute Disease↗
PubMed2004

Pulsed tissue Doppler imaging detects early myocardial dysfunction in asymptomatic patients with severe mitral regurgitation.

OBJECTIVE: To assess whether tissue Doppler myocardial imaging (TDI) indices can predict postoperative left ventricular function in patients with mitral regurgitation (MR) after surgical correction. METHODS: 84 patients (mean (SD) age 54.3 (10.8) years) with asymptomatic severe MR, an end systolic diameter < 45 mm, and an ejection fraction (EF) > 60% were subdivided in two groups: 43 patients with a postoperative EF reduction < 10% (group 1) and 41 patients with a postoperative EF reduction > or = 10% (group 2).TDI systolic indices of the lateral annulus were analysed preoperatively to assess myocardial systolic wave (Sm) velocity, myocardial precontraction time (PCTm), myocardial contraction time (CTm), and the PCTm:CTm ratio. RESULTS: Postoperative EF decreased significantly (from 67 (5)% to 60 (5.5)%, p = 0.0001). Group 2 had a higher PCTm, CTm, and PCTm:CTm ratio and a lower Sm velocity than group 1 (PCTm 100.4 (19) ms v 82 (21.8) ms, p = 0.004; CTm 222 (3.1) ms v 215 (2.3) ms, p = 0.01; PCTm:CTm 0.45 (0.08) v 0.38 (0.09), p = 0.001; Sm velocity 10.4 (1.1) cm/s v 13 (1.3) cm/s, p = 0.0001). Multivariate regression analysis showed that the combination of PCTm:CTm ratio > or = 40 ms and Sm velocity < or = 10.5 cm/s was the main independent predictor of postoperative EF reduction > or = 10% (sensitivity 78%, specificity 95%). CONCLUSIONS: TDI systolic indices can predict postoperative left ventricular function in patients with asymptomatic MR undergoing surgical correction.

Cardiomyopathies↗
PubMed2003

The "clover technique" as a novel approach for correction of post-traumatic tricuspid regurgitation.

OBJECTIVE: To describe a novel technique, named "clover," to correct complex post-traumatic tricuspid valve lesions. METHODS: Five patients with severe post-traumatic tricuspid insufficiency underwent valve reconstruction with the clover technique, a new surgical approach that consists of stitching together the middle point of the free edges of the tricuspid leaflets, producing a clover-shaped valve. The mechanism of tricuspid regurgitation was complex in all patients, and right ventricular function was always moderately to severely depressed. An echocardiographic study was performed after cardiopulmonary bypass, at discharge, and at follow-up. RESULTS: Cardiopulmonary bypass time was 32 +/- 6.3 minutes and crossclamp time was 23 +/- 7.4. There was no hospital mortality or morbidity. Intraoperative transesophageal and predischarge transthoracic echocardiography showed perfect results in all patients. No late deaths occurred. At the latest follow-up, extending to 14.2 months (mean 11.3; median 12.4), all patients were asymptomatic (New York Heart Association class I) with trivial (2 patients) or no residual regurgitation (3 patients) on 2-dimensional echocardiogram. No transvalvular gradient was revealed in any patient. A significant reduction of the right ventricular end-diastolic dimensions was noted as well (from 54 +/- 7.1 mm to 40 +/- 7.5 mm, P <.001). CONCLUSIONS: In this preliminary experience, the clover technique increased the feasibility of tricuspid valve repair in case of severe traumatic tricuspid valve insufficiency, leading to very satisfactory mid-term results even in the presence of complex lesions or dilatation and deterioration of the right ventricle.

Adult↗
PubMed2002

Inaccuracy of four coronary surgery risk-adjusted models to predict mortality in individual patients.

OBJECTIVES: This study was undertaken to evaluate the accuracy of four different risk-adjusted models in predicting mortality in individual patients who are undergoing coronary artery by-pass graft surgery. In the last decade several models to stratify patients before open heart surgery, according to factors affecting mortality, were developed with the aim of retrospectively comparing outcomes of open heart surgery, based on reliable stratification of case-mix, and of prospectively identifying high risk patients as a basis for a meaningful informed consent for patients counseling. METHODS: The pre-operative risk of death was calculated with four different models in 418 consecutive patients who underwent coronary artery by-pass surgery and then compared with the actual outcome. To discriminate patients with favorable and unfavorable outcome, the logistic regression analysis and the areas under the receiver-operating-characteristic curves were applied. The accuracy score was used to evaluate the reliability of each score to predict the individual outcome. RESULTS: Seven deaths (1.7%) were observed within 30 days from the operation, and the overall incidence was similar to that predicted by all models. Only the NBI score was not able to discriminate survivors from patients who will die, and the areas under the curves were 0.596 for the Parsonnet score, 0.861 for the Cleveland Clinic Foundation score, 0.823 for the French score, and 0.806 for the EuroSCORE. The four models were highly accurate (between 0.97 and 0.98) to predict the overall mortality. In seven patients who died the mean predictive scores were very low and ranged between 2.1 and 4.6, but were significantly higher than those of patients who survived (between 1.1 and 2.2). CONCLUSIONS: The four pre-surgical predictive models were similarly able to discriminate favorable vs. unfavorable outcomes and highly accurate to predict overall mortality, but very inaccurate to predict mortality in individual patients.

Adult↗
PubMed2002

Revascularization of hibernating myocardium: rate of metabolic and functional recovery and occurrence of oxidative stress.

BACKGROUND: Left ventricular (LV) dysfunction due to coronary artery disease (CAD) may improve after revascularization in patients with hibernating myocardium (HM). METHODS AND RESULTS: We compared the rate of metabolic (arterial-great cardiac vein differences of lactate, glucose and pyruvate) and functional (intra-operative transesophageal and epicardial echocardiography) recovery and occurrence of oxidative stress (myocardial release of oxidized glutathione (GSSG)) early after surgical revascularization, in patients with CAD, LV dysfunction and HM (n=16) vs those with preserved LV function (n=15). By comparing the two groups, we observed that, after de-clamping, in patients with HM (a) the kinetic of lactate production was converted to extraction (P<0.01 at 1, 5, 10 and 20 min after revascularization), (b) myocardial extraction of pyruvate increased (P<0.01 during the first 5 min after revascularization), (c) GSSG release was less and of shorter duration (P<0.01 at all times), (d) segmental wall motion score improved from 2.4+/-0.3 to 1.7+/-0.5 (P<0.01) as did the thickening of the akinetic territories corresponding to the antero-distal septum and to the distal anterior wall regions (to 36+/-23%, and to 36+/-13%, respectively). There was a correlation between the rate of recovery of metabolic and functional indices. CONCLUSIONS: The contractile and metabolic recovery of HM is more rapid than that of non-HM, and it is not accompanied by oxidative stress.

Blood Glucose↗
PubMed2002

Beating-heart coronary artery bypass graft surgery at San Raffaele Hospital: four years of experience.

OBJECTIVE: To review the database of 1,902 consecutive patients who underwent coronary artery bypass graft (CABG) surgery in the period 1998 through 2001 at this institution, and to compare the preoperative status, anesthetic management, and postoperative outcome of 364 patients with the beating-heart technique with 1,538 patients who underwent the operation on cardiopulmonary bypass. DESIGN: Observational study. SETTING: University hospital. PARTICIPANTS: Consecutive patients (n = 1,902) who underwent CABG surgery in the period 1998 through 2001. MEASUREMENTS AND MAIN RESULTS: Comparison (chi-square test) of the preoperative status shows that surgeons' choice for the beating-heart technique was based on the presence of severe preoperative comorbidities: renal impairment (p < 0.0001), chronic obstructive pulmonary disease (p < 0.04), and low ejection fraction (p < 0.0001). On a multivariate analysis, the beating-heart technique was associated with reduced transfusion needs and duration of mechanical ventilation. CONCLUSION: Beating-heart surgery is gaining popularity as a safe method for myocardial revascularization. Excellent results have been achieved with this technique in this center.

Cardiopulmonary Bypass↗
PubMed2002

A simplified technique for antegrade selective cerebral perfusion.

Various methods of cerebral protection have been used during aortic arch surgery. We reviewed our experience with a modified technique for selective cerebral perfusion (SCP) administration during surgery on the thoracic aorta from October 1999. Conventionally, this technique requires an additional roller pump on the cardiopulmonary bypass (CPB) console. In order to simplify the extracorporeal circuit (ECC), the paediatric double-roller pump used for the administration of cardioplegia was utilized by adding a 'Y-connection' on the blood line of the cardioplegia circuit, upstream of the cardioplegia reservoir, to provide SCP blood flow. SCP administration with a Y-connection is both easy and fast to set up on the ECC circuit and does not create additional difficulties to the surgeon. It simplifies SCP delivery by allowing the perfusionist to use a standard ECC system set-up.

Adult↗
PubMed2001

Atrial electroanatomic remodeling after circumferential radiofrequency pulmonary vein ablation: efficacy of an anatomic approach in a large cohort of patients with atrial fibrillation.

BACKGROUND: Circumferential radiofrequency ablation around pulmonary vein (PV) ostia has recently been described as a new anatomic approach for atrial fibrillation (AF). METHODS AND RESULTS: We treated 251 consecutive patients with paroxysmal (n=179) or permanent (n=72) AF. Circular PV lesions were deployed transseptally during sinus rhythm (n=124) or AF (n=127) using 3D electroanatomic guidance. Procedures lasted 148+/-26 minutes. Among 980 lesions surrounding individual PVs (n=956) or 2 ipsilateral veins with close openings or common ostium (n=24), 75% were defined as complete by a bipolar electrogram amplitude <0.1 mV inside the lesion and a delay >30 ms across the line. The amount of low-voltage encircled area was 3594+/-449 mm(2), which accounted for 23+/-9% of the total left atrial (LA) map surface. Major complications (cardiac tamponade) occurred in 2 patients (0.8%). No PV stenoses were detected by transesophageal echocardiography. After 10.4+/-4.5 months, 152 patients with paroxysmal AF (85%) and 49 with permanent AF (68%) were AF-free. Patients with and without AF recurrence did not differ in age, AF duration, prevalence of heart disease, or ejection fraction, but the LA diameter was significantly higher (P<0.001) in permanent AF patients with recurrence. The proportion of PVs with complete lesions was similar between patients with and without recurrence, but the latter had larger low-voltage encircled areas after radiofrequency (expressed as percent of LA surface area; P<0.001). CONCLUSIONS: Circumferential PV ablation is a safe and effective treatment for AF. Its success is likely due to both PV trigger isolation and electroanatomic remodeling of the area encompassing the PV ostia.

Atrial Fibrillation↗
PubMed2001

Tranexamic acid in off-pump coronary surgery: a preliminary, randomized, double-blind, placebo-controlled study.

BACKGROUND: We evaluated the hemostatic effects of tranexamic acid, a synthetic antifibrinolytic drug, in patients undergoing beating-heart coronary surgery. METHODS: Forty consecutive patients were in a double-blind manner, prospectively randomized into two groups: 20 patients received tranexamic acid (bolus of 1 g before skin incision, followed by continuous infusion of 400 mg/hr during surgery), and 20 patients received saline. As primary outcomes, bleeding and allogeneic transfusions were considered. D-dimer and fibrinogen plasma levels were also evaluated to monitor the activation of fibrinolysis. Major postoperative thrombotic events, as a potential consequence of antifibrinolytic treatment, were recorded. RESULTS: The treatment group had significantly lower postoperative bleeding (median [25th to 75th percentiles]: 400 mL [337 to 490 mL] vs 650 ml [550 to 862 mL], p < 0.0001), lower need for allogeneic blood products (1,200 vs 5,300 mL, p < 0.001), and lower postoperative D-dimer plasma levels. No postoperative thrombotic complications were observed in either group. CONCLUSIONS: In this initial series of patients undergoing off-pump coronary surgery, tranexamic acid appears to be effective in reducing postoperative bleeding and the need for allogeneic blood products.

Aged↗
PubMed2001

Totally endoscopic computer-enhanced atrial septal defect closure in six patients.

BACKGROUND: Totally endoscopic procedures have been introduced into cardiac surgery with the application of telemanipulating robotic systems. We report 6 cases of closed-chest atrial septal defect (ASD) closure using a robotic device. METHODS: After deflating the right lung, the endoscopic camera and two robotic arms were inserted into the right hemithorax through 8-mm ports. An accessory port was placed for blood suction and for introduction of ancillary endoscopic instruments. After femoral-femoral cannulation for cardiopulmonary bypass (CPB), aortic occlusion, and cardioplegia delivery, the intracardiac correction was carried out in 5 patients with an ostium secundum ASD and in 1 patient with a patent foramen ovale (PFO) and atrial septal aneurysm (ASA). The ASDs were closed with a continuous braided polyester suture. The PFO closure with septal aneurysm plication was carried out with interrupted stiches. RESULTS: Mean CPB and cross-clamp times were 106 +/- 22 and 67 +/- 13 minutes, respectively. Extubation was carried out within the seventh postoperative hour. All patients returned to normal function within the first postoperative week. CONCLUSIONS: Totally endoscopic ASD closure can be carried out safely using robotic techniques with rapid postoperative recovery and an excellent cosmetic result.

Adolescent↗
PubMed2001

Cardiac echinococcus complicated by ventricular tachycardia.

Echinococcosis is a parasitic disease that usually involves lungs and liver. Occasionally, it localizes in the heart (less than 2% of cases). We present a case of an adult patient with cardiac echinococcosis complicated by ventricular tachycardia. The diagnosis, based on transthoracic two-dimensional echocardiography, magnetic resonance imaging (MRI), and computerized tomography (CT), was confirmed by surgery.

Adult↗
PubMed2001

The double-orifice technique in mitral valve repair: a simple solution for complex problems.

OBJECTIVE: The aim of this study is to report our results with the central double-orifice technique used for the treatment of complex mitral valve lesions. METHODS: The central double-orifice repair has been used in 260 patients (mean age, 56 +/- 14.3 years) over a period of 7 years. The mechanism responsible for mitral regurgitation was prolapse of both leaflets in 148 patients, prolapse of the anterior leaflet in 68, prolapse of the posterior leaflet with annular calcification or other unfavorable features in 31, and lack of leaflet coaptation for restricted motion or erosion of the free edge in 13. Degenerative disease was the cause of mitral regurgitation in 80.8% of the patients, rheumatic disease was the cause in 9.6%, endocarditis was the cause in 6.1%, and ischemic disease was the cause in 2.3%. RESULTS: Hospital mortality was 0.7%, and the overall survival at 5 years was 94.4% +/- 2.59%. Thirteen patients required a reoperation (2 early postoperatively and 11 late during the follow-up), for an overall freedom from reoperation of 90.0% +/- 3.37% at 5 years. Freedom from reoperation was lower in patients with rheumatic valve disease and in patients who did not undergo an annuloplasty procedure. CONCLUSIONS: The effectiveness and durability of the central double-orifice technique were assessed in this study. This type of repair can be a useful addition to the surgical armamentarium in mitral valve reconstruction.

Adolescent↗
PubMed2001

Tranexamic acid administration after cardiac surgery: a prospective, randomized, double-blind, placebo-controlled study.

BACKGROUND: Many different doses and administration schemes have been proposed for the use of the antifibrinolytic drug tranexamic acid during cardiac surgery. This study evaluated the effects of the treatment using tranexamic acid during the intraoperative period only and compared the results with the effects of the treatment continued into the postoperative period. METHODS: Patients undergoing elective cardiac surgery with use of cardiopulmonary bypass (N = 510) were treated intraoperatively with tranexamic acid and then were randomized in a double-blind fashion to one of three postoperative treatment groups: group A: 169 patients, infusion of saline for 12 h; group B: 171 patients, infusion of tranexamic acid, 1 mg x kg(-1) x h(-1) for 12 h; group C: 170 patients, infusion of tranexamic acid, 2 mg x kg(-1) x h(-1) for 12 h. Bleeding was considered to be a primary outcome variable. Hematologic data, allogeneic transfusions, thrombotic complications, intubation time, and intensive care unit and hospital stay duration also were evaluated. RESULTS: No differences were found among groups regarding postoperative bleeding and outcomes; however, the group treated with 1 mg x kg(-1) x h(-1) tranexamic acid required more units of packed red blood cells because of a significantly lower basal value of hematocrit, as shown by multivariate analysis. CONCLUSIONS: Prolongation of treatment with tranexamic acid after cardiac surgery is not advantageous with respect to intraoperative administration alone in reducing bleeding and number of allogeneic transfusions. Although the prevalence of postoperative complications was similar among groups, there is an increased risk of procoagulant response because of antifibrinolytic treatment. Therefore, the use of tranexamic acid during the postoperative period should be limited to patients with excessive bleeding as a result of primary fibrinolysis.

Adult↗
PubMed2001

Activation of coagulation and fibrinolysis during coronary surgery: on-pump versus off-pump techniques.

BACKGROUND: The authors studied the changes in selected hemostatic variables in patients undergoing coronary surgery with on-pump coronary artery bypass grafting (CABG) or off-pump coronary artery bypass surgery (OPCAB) techniques. METHODS: Platelet counts and plasma concentrations of antithrombin, fibrinogen, D dimer, alpha(2) antiplasmin, and plasminogen were measured preoperatively, 5 min after administration of heparin, 10 min after arrival in the intensive care unit, and 24 h after surgery in patients scheduled to undergo OPCAB (n = 15) or CABG (n = 15). To correct for dilution, hemostatic variables and platelet counts were adjusted for the changes in immunoglobulin G plasma concentrations and hematocrit, respectively. RESULTS: Adjusting for dilution, antithrombin and fibrinogen concentrations decreased to a similar extent in patients undergoing OPCAB or CABG (pooled means and 95% confidence limits of the mean: 95.5% of baseline, 93-98%, P = 0.002, and 91.7% of baseline, 88-95%, P = 0.0001), respectively, whereas alpha(2)-antiplasmin concentrations were unchanged. Only CABG was associated with a reduction in platelet counts (76% of baseline, 66-85%, P = 0.0001), plasminogen concentrations (96% of baseline, 91-99%, P = 0.011), and increased D-dimer formation (476%, 309-741%, P = 0.004). Twenty-four hours after surgery, platelet counts were still lower in patients undergoing CABG (P = 0.049), but all the investigated variables adjusted for dilution were similar in the two groups. CONCLUSIONS: Coronary surgery causes a net consumption of antithrombin and fibrinogen. A transient decrease in platelet counts, with plasminogen activation and increased D-dimer formation, however, is only observed with CABG. Twenty-four hours after surgery, the hemostatic profiles of patients in both groups are similar.

Blood Coagulation↗
PubMed2001

Mean cardiac output by thermodilution with a single controlled injection.

OBJECTIVE: A new method to estimate mean cardiac output by thermodilution with a single duration-controlled injection was evaluated in patients. DESIGN: Prospective criterion standard study. SETTING: University hospital cardiac surgical intensive care unit and cardiac operation room. PATIENTS: Of 33 patients, 24 underwent coronary bypass graft surgery, four had a valve replacement, and five were treated in the intensive care unit. INTERVENTIONS: Interventions consisted of thermodilution cardiac output measurements. One single duration-controlled injection of cold fluid was used to calculate cardiac output. This controlled injection was performed with a duration equal to one whole ventilation cycle of the ventilator. An algorithm adapted to this duration-controlled injection calculated cardiac output. Moreover, this algorithm has properties to reduce errors caused by artificial ventilation and thermal noise. MEASUREMENTS AND MAIN RESULTS: In 33 patients, the averaged values of four measurements equally spread over the ventilatory cycle (phase-controlled) were compared with the values of two single duration-controlled measurements. The measurements were performed during periods of stable respiration and circulation. No significant difference was observed between the mean of four phase-controlled measurements and the mean of the two duration-controlled measurements. The cardiac output values in the intensive care patients were significantly higher compared with the two other patient groups (p <.05). The difference between the two methods could not be subdivided for the three patient groups (p >.05). The coefficient of variation of the single duration-controlled thermodilution measurements was significantly lower than the single phase-controlled measurements, 3% vs. 6% (p <.01). CONCLUSIONS: One single duration-controlled injection thermodilution measurement is as accurate and repeatable as the mean of four phase-controlled measurements and is clinically feasible.

Adult↗