In Silico Shear and Intramural Stresses are Linked to Aortic Valve Morphology in Dilated Ascending Aorta.

OBJECTIVE/BACKGROUND: The development of ascending aortic dilatation in patients with bicuspid aortic valve (BAV) is highly variable, and this makes surgical decision strategies particularly challenging. The purpose of this study was to identify new predictors, other than the well established aortic size, that may help to stratify the risk of aortic dilatation in BAV patients. METHODS: Using fluid-structure interaction analysis, both haemodynamic and structural parameters exerted on the ascending aortic wall of patients with either BAV (n = 21) or tricuspid aortic valve (TAV; n = 13) with comparable age and aortic diameter (42.7 ± 5.3 mm for BAV and 45.4 ± 10.0 mm for TAV) were compared. BAV phenotypes were stratified according to the leaflet fusion pattern and aortic shape. RESULTS: Systolic wall shear stress (WSS) of BAV patients was higher than TAV patients at the sinotubular junction (6.8 ± 3.3 N/m2 for BAV and 3.9 ± 1.3 N/m2 for TAV; p = .006) and mid-ascending aorta (9.8 ± 3.3 N/m2 for BAV and 7.1 ± 2.3 N/m2 for TAV; p = .040). A statistically significant difference in BAV versus TAV was also observed for the intramural stress along the ascending aorta (e.g., 2.54 × 105 ± 0.32 × 105 N/m2 for BAV and 2.04 × 105 ± 0.34 × 105 N/m2 for TAV; p < .001) and pressure index (0.329 ± 0.107 for BAV and 0.223 ± 0.139 for TAV; p = .030). Differences in the BAV phenotypes (i.e., BAV type 1 vs. BAV type 2) and aortopathy (i.e., isolated tubular vs. aortic root dilatations) were associated with asymmetric WSS distributions in the right anterior aortic wall and right posterior aortic wall, respectively. CONCLUSION: These findings suggest that valve mediated haemodynamic and structural parameters may be used to identify which regions of aortic wall are at greater stress and enable the development of a personalised approach for the diagnosis and management of aortic dilatation beyond traditional guidelines.

Primary graft failure after heart transplantation: the importance of donor pharmacological management.

BACKGROUND: Primary graft failure (PGF) remains the strongest determinant of perioperative mortality after heart transplantation (HT). Donor management may play an important role in the incidence of PGF. MATERIALS AND METHODS: Multivariate analysis was used to identify PGF determinants after HT. Donor and recipient data were analyzed together with preharvest management information and perioperative results. PGF was defined as the need for mechanical circulatory support immediately post-HT. RESULTS: Isolated HT was performed in 54 consecutive patients from January 2006 to June 2009. PGF occurred in 11 (20%) patients. Upon univariate analysis, preoperative mean pulmonary arterial pressure was significantly higher among patients developing PGF (P=.02). The donors for PGF patients had more often been managed with high inotropic support (dopamine>10 microg/kg/min and/or alpha agonists>0.06 microg/kg/min; P=.008). In contrast, death for head trauma was more common among donors for patients who did not develop PGF (P=.02). In-hospital mortality was 13% (7/54); 71% of these deceased patients displayed PGF (5/7). Upon multivariate analysis, preharvest high donor inotropic support was the strongest determinant of PGF (P=.01, odds ratio [OR]=7.5). Donor death due to head trauma showed a protective effect against PGF (P=.03, OR=0.1). CONCLUSION: PGF remains a lethal perioperative complication despite modern tools for prompt cardiac mechanical assistance. As a result of the organ shortage, many centers accept marginal hearts assuming that donor hemodynamic management shows a reduced impact on PGF. We suggest a timely evaluation of the hazards for PGF whenever high inotropic support is used, especially among donors dying for causes other than head trauma.

Right aortic arch with aberrant left innominate artery: MR imaging findings.

A rare case of a 60-year-old man with a right aortic arch and aberrant left innominate artery is presented. This case had an unusual clinical presentation. The dysphagia appeared suddenly in adulthood, whereas vascular rings, when symptomatic, usually manifest early in childhood. To our knowledge, MR imaging findings of this anomaly have never been reported. The diagnosis was made by MR imaging and confirmed by surgery. Magnetic resonance imaging can replace angiography in the assessment of the aortic arch anomalies.

Haemodynamic and organ blood flow responses to sevoflurane during spontaneous ventilation in the rat: a dose-response study.

To determine the systemic haemodynamic and organ blood flow responses to the administration of sevoflurane during spontaneous ventilation, heart rate, cardiac index, mean arterial pressure, arterial blood gases, and blood flows to the brain, spinal cord, heart, kidneys and splanchnic organs were measured awake (control values) and after 30 min of anaesthesia with 0.5, 1.0, 1.2 or 1.5 MAC sevoflurane in rats. Cardiac output and organ blood flows were measured using radiolabelled microspheres. The MAC (mean +/- SEM) of sevoflurane was found to be 2.30 +/- 0.05%. At each concentration, haemodynamic variables were similar to awake values with the exception of a 12% reduction in mean arterial pressure at 1.5 MAC (P less than 0.01). Arterial PCO2 increased in a dose-related fashion. Cerebral and spinal cord blood flows increased at 1.2 and 1.5 MAC whereas coronary and renal blood flows did not change significantly. Portal tributary blood flow and preportal vascular resistance were unaffected. Hepatic arterial flow increased by 63% at 1.5 MAC (P less than 0.05) but total liver blood flow remained unchanged compared with awake values. In conclusion, the administration of sevoflurane during spontaneous ventilation produces a high degree of cardiovascular stability and maintains blood flow to major organs in the rat.

Transcranial Doppler: response of cerebral blood-flow velocity to carbon dioxide in anaesthetized children.

To determine the effect of carbon dioxide on the cerebral circulation in anaesthetized infants and children, 13 healthy children, ASA physical status I or II, between three months and seven years of age and scheduled for urologic surgery, were studied. Anaesthesia was induced with thiopentone and vecuronium. After tracheal intubation, anaesthesia was maintained with 70 per cent nitrous oxide in oxygen, fentanyl 2 micrograms.kg-1, vecuronium 0.05 mg.kg-1 and 0.8-1.0 per cent end-tidal isoflurane. A caudal block was performed before surgery. Systolic arterial pressure, heart rate, oxygen saturation, temperature, and end-tidal isoflurane were maintained constant. Ventilation was adjusted to achieve an end-tidal PCO2 (PETCO2) of 20 mmHg. The PETCO2 was then randomly adjusted between 20 and 80 mmHg by the addition of carbon dioxide from an exogenous source. Cerebral blood flow velocity increased logarithmically and directly with the PETCO2 (r2 = 0.56). There were no complications associated with the use of transcranial Doppler sonography. These data indicate that CO2 has a direct effect on the velocity of blood in the middle cerebral artery in infants and children anaesthetized with isoflurane.

Surgical repair of type II truncus arteriosus without a conduit.

A technique for reconstructing the right ventricular outflow tract in an infant with type II truncus arteriosus without using a prosthetic conduit is described. The truncal root is transected, and the confluence of branch pulmonary arteries is brought anterior to the aorta by using Lecompte's maneuver. The aorta is then reconstructed directly with an end-to-end anastomosis. The right ventricular outflow tract is reconstructed by anastomosing the posterior wall of the confluence directly to the apex of the vertical right ventriculotomy. A glutaraldehyde-preserved pericardial patch is then placed anteriorly to complete reconstruction of the right ventricular outflow tract.