Quantification of visceral perfusion and impact of femoral cannulation: in vitro model of aortic dissection

Comparison of clinical outcomes between double arterial cannulation and single arterial cannulation in type A aortic dissection

It remains controversial as to which optimal cannulation strategy ought to be employed in surgery for type A aortic dissection (TAAD). The aim of this study was to make a comparison of the clinical outcomes between single and double arterial cannulation. From January 2018 to December 2022, 403 individuals with TAAD were recruited for the study and were divided into two groups based on the cannulation approach. A total of 206 patients underwent single arterial cannulation, while 197 patients underwent double arterial cannulation. In order to balance the data encompassing specific pathological traits, stabilized inverse probability weighting (IPTW) was utilized. Confounding variables that could potentially be associated with the outcomes were adjusted by means of multivariate logistic regression analysis with IPTW. There was a significant difference in in-hospital mortality (19.9% versus 9.1% for single versus double arterial cannulation, respectively, P < 0.01). The incidence of stroke and acute kidney injury requiring dialysis was lower in the double arterial cannulation group than in the single artery cannulation group, but there was no statistical difference. Compared with the single arterial cannulation cohort, the IPTW adjusted odds ratios for in-hospital mortality and stroke in the double arterial cannulation cohort were 0.436 (95% CI, 0.211-0.903, P < 0.01) and 0.52 (95% CI, 0.3-0.89, P = 0.017), respectively. Double arterial cannulation served as a protective factor for in-hospital mortality and stroke. Consistent findings were noted upon stratification based on age, sex, BMI, and the duration of cardiopulmonary bypass. By providing stable systemic organ perfusion, the establishment of CPB with DAC can constitute a safe technique for TAAD repair.

Impact of direct mesenteric perfusion on malperfusion in acute type A aortic dissection repair

OBJECTIVES

Mesenteric malperfusion in acute aortic dissection remains a life-threatening complication with no standardized treatment strategy. This study aimed to describe and evaluate the outcomes of our integrated approach combining exploratory laparotomy, immediate mesenteric reperfusion, and central aortic repair.

METHODS

We retrospectively reviewed patients with acute aortic dissection with a preoperative diagnosis of mesenteric malperfusion who were treated between August 2011 and November 2022. Our surgical approach was to establish cardiopulmonary bypass, followed by exploratory laparotomy with mesenteric artery flow assessment using Doppler ultrasound and direct perfusion if needed, central aortic repair, and subsequent mesenteric artery reconstruction. The primary end-point was the 30-day operative mortality.

RESULTS

Among 217 patients with acute aortic dissection, 12 (5.5%) had mesenteric malperfusion on preoperative computed tomography. Ten patients underwent exploratory laparotomy, where Doppler ultrasonography revealed reduced mesenteric blood flow in five patients (2.3% of the total 217 patients). These patients underwent direct perfusion of the mesenteric artery via a side branch of the cardiopulmonary bypass circuit. Doppler ultrasound confirmed the restoration of mesenteric blood flow in all perfused patients. No bowel resections were required. The operative mortality in patients with mesenteric malperfusion was 20%. The causes of death were stroke (n = 1) and acute myocardial infarction (n = 1).

CONCLUSIONS

Our integrated surgical strategy combining central aortic repair with concurrent exploratory laparotomy and immediate mesenteric perfusion demonstrated technical feasibility in managing mesenteric malperfusion during aortic repair. Further prospective studies with larger cohorts are warranted to validate these findings.

Carotid versus axillary artery cannulation for descending aorta remodeling in type A acute aortic dissection

BACKGROUND

Arterial cannulation sites for the surgical repair of type A aortic dissection (AAD) have evolved from right axillary artery (AA) cannulation to bilateral carotid artery (CA) based of femoral artery (FA) cannulation. Postoperative descending aorta remodeling is closely linked to the false lumen area ratio (FLAR), defined as false lumen area/aortic area, as well as to the incidence of renal replacement therapy (RRT).

AIM

To investigate the effect of the updated arterial cannulation strategy on descending aortic remodeling.

METHODS

A total of 443 AAD patients who received FA combined cannulation between March 2015 and March 2023 were included in the study. Of these, 209 received right AA cannulation and 234 received bilateral CA cannulation. The primary outcome was the change in FLAR, as calculated from computed tomography angiography in three segments of the descending aorta: Thoracic (S1), upper abdominal (S2), and lower abdominal (S3). Secondary outcomes were the incidence of RRT and the serum inflammation response, as observed by the levels of high sensitivity C reaction protein (hs-CRP) and Interleukin-6 (IL-6).

RESULTS

The postoperative/preoperative ratio of FLAR in S2 and S3 was higher in the AA group compared to the CA group (S2: 0.80 ± 0.08 vs 0.75 ± 0.07, P < 0.001; S3: 0.57 ± 0.12 vs 0.50 ± 0.12, P < 0.001, respectively). The AA group also had a significantly higher incidence of RRT (19.1% vs 8.5%, P = 0.001; odds ratio: 2.533, 95%CI: 1.427-4.493) and higher levels of inflammation cytokines 24 h after the procedure [hr-CRP: 117 ± 17 vs 104 ± 15 mg/L; IL-6: 129 (103, 166) vs 83 (69, 101) pg/mL; both P < 0.001] compared to the CA group.

CONCLUSION

The CA cannulation strategy was associated with better abdominal aorta remodeling after AAD repair compared to AA cannulation, as observed by a greater change in FLAR and lower incidence of RRT.

4D-Flow MRI and Vector Ultrasound in the In-Vitro Evaluation of Surgical Aortic Heart Valves - a Pilot Study

INTRODUCTION

The aim of this study was the initial investigation of 4D-Flow MRI and Vector Ultrasound as novel imaging techniques in the in-vitro analysis of hemodynamics in anatomical models. Specifically, by looking at the hemodynamic performance of state-of-the-art surgical heart valves in a 3D-printed aortic arch.

METHODS

The mock circulatory loop simulated physiological, pulsatile flow. Two mechanical and three biological aortic valves prostheses were compared in a 3D-printed aortic arch. 4D magnetic resonance imaging and vector flow Doppler ultrasound served as imaging methods. Hemodynamic parameters such as wall shear stress, flow velocities and pressure gradients were analyzed.

RESULTS

The flow analysis revealed characteristic flow-patterns in the 3D-printed aortic arch. The blood-flow in the arch presented complex patterns, including the formation of helixes and vortices. Higher proximal peak velocities and lower flow volumes were found for biological valves.

CONCLUSION

The mock circulatory loop in combination with modern radiological imaging provides a sufficient basis for the hemodynamic comparison of aortic valves.

Cannulation Strategies in Type A Aortic Dissection: Overlooked Details and Novel Approaches

Aortic dissection type A is a life-threatening condition that frequently necessitates surgical intervention. This review focuses on central aortic cannulation, arch branch vessel (ABV) cannulation, and proximal arch cannulation as key techniques during aortic surgery. It discusses innovative solutions for addressing these challenges. The review synthesizes findings from recent studies and emphasizes the significance of meticulous planning and execution of cannulation in aortic dissection repair. This review aims to contribute to the advancement of surgical practices and the enhancement of patient outcomes in the management of type A aortic dissection (AAD) by addressing these frequently overlooked details.

Assessing the impact of turbulent kinetic energy boundary conditions on turbulent flow simulations using computational fluid dynamics

Computational fluid dynamics has been widely used to study hemodynamics, but accurately determining boundary conditions for turbulent blood flow remains challenging. This study aims to investigate the effect of patient-specific turbulence boundary conditions on the accuracy of turbulent flow simulation. Using a stenosis model with 50% severity in diameter, the post-stenosis turbulence flow region was simulated with different planes to obtain inlet boundary conditions and simulate downstream flows. The errors of simulated flow fields obtained with turbulence kinetic energy (TKE) boundary data and arbitrary turbulence intensity were compared. Additionally, the study tested various TKE data resolutions and noise levels to simulate experimental environments. The mean absolute error of velocity and TKE was investigated with various turbulence intensities and TKE mapping. While voxel size and signal-to-noise ratio of the TKE data affected the results, simulation with SNR > 5 and voxel size < 10% resulted in better accuracy than simulations with turbulence intensities. The simulation with appropriate TKE boundary data resulted in a more accurate velocity and turbulence field than those with arbitrary turbulence intensity boundary conditions. The study demonstrated the potential improvement of turbulent blood flow simulation with patient-specific turbulence boundary conditions, which can be obtained from recent measurement techniques.

Fluid-structure interaction simulation of visceral perfusion and impact of different cannulation methods on aortic dissection

Hemodynamics in aortic dissection (AD) is closely associated with the risk of aortic aneurysm, rupture, and malperfusion. Altered blood flow in patients with AD can lead to severe complications such as visceral malperfusion. In this study, we aimed to investigate the effect of cannulation flow on hemodynamics in AD using a fluid-structure interaction simulation. We developed a specific-idealized AD model that included an intimal tear in the descending thoracic aorta, a re-entry tear in the left iliac artery, and nine branches. Two different cannulation methods were tested: (1) axillary cannulation (AC) only through the brachiocephalic trunk and (2) combined axillary and femoral cannulation (AFC) through the brachiocephalic trunk and the right common iliac artery. AC was found to result in the development of a pressure difference between the true lumen and false lumen, owing to the difference in the flow rate through each lumen. This pressure difference collapsed the true lumen, disturbing blood flow to the celiac and superior mesenteric arteries. However, in AFC, the pressure levels between the two lumens were similar, and no collapse occurred. Moreover, the visceral flow was higher than that in AC. Lastly, the stiffness of the intimal flap affected the true lumen's collapse.