Tear Size and Location Influence the Pressure of False Lumen Following Type A Aortic Dissection: Perspective of Current Evidence

Nonocclusive Mesenteric Ischemia in Aortic Surgery: What You Need to Know

BACKGROUND

Nonocclusive mesenteric ischemia (NOMI), a subtype of acute mesenteric ischemia (AMI), is primarily caused by mesenteric arterial vasoconstriction and decreased vascular resistance, leading to impaired intestinal perfusion.Commonly observed after cardiac surgery, NOMI affects older patients with cardiovascular or systemic diseases, accounting for 20-30% of AMI cases with a mortality rate of ∼50%. This review explores NOMI's pathophysiology, clinical implications in aortic dissection, and the unmet needs in diagnosis and management, emphasizing its prognostic significance.

METHODS

A comprehensive literature review was conducted using multiple electronic databases to extract relevant data and information.

RESULTS

NOMI is a life-threatening condition characterized by mesenteric vasoconstriction and reduced splanchnic blood flow, often triggered by cardiac surgery, hemodialysis, or hypotensive episodes. Epidemiological studies highlight its prevalence in intensive care unit settings, with a high mortality rate linked to delayed diagnosis and systemic hypoperfusion. Risk factors include advanced age, vasopressor use, and inflammatory markers. Biomarkers such as intestinal fatty acid binding protein, citrulline, and D-lactate show potential for early detection but lack robust clinical validation. Management includes fluid resuscitation, vasodilators, and surgical intervention for bowel necrosis. Emerging endovascular approaches show promise but are limited to select cases without bowel infarction. This review underscores the critical need for timely diagnosis, risk factor identification, and tailored interventions to improve outcomes.

CONCLUSION

NOMI remains poorly understood despite advances in surgical and perioperative care. Its pathophysiology, linked to cardiopulmonary bypass and intraoperative factors, requires heightened clinical vigilance. Limited evidence underscores the need for a multidisciplinary approach involving surgeons, radiologists, and anesthetists to improve diagnosis, management, and outcomes in aortic surgery patients.

Relationship between false lumen morphology and entry tear in acute type A aortic dissection

OBJECTIVES

This study aimed to investigate the relationship between false lumen morphology and the size, aortic segment and position of the entry tear for acute type A aortic dissection.

METHODS

The records of patients who underwent emergency operation for acute type A aortic dissection in our institution between April 2011 and May 2022 were examined. Data regarding size, location and position of the entry tear and preoperative computed tomography findings were reviewed. The relationship of these variables with false lumen morphology was examined and retrospectively compared according to tear size.

RESULTS

Of 243 cases, characteristics of the entry tear, visualized during surgery, were confirmed in 134 cases (age = 70.9 ± 12.6 years, male = 45.5%). Tear sizes at different aortic segments were not significantly different (P = 0.376). Tears posterior to the lesser curvature were significantly smaller than those anterior to the greater curvature (P = 0.004). A thrombosed false lumen was associated with a significantly smaller tear size and position on the posterior to the lesser curvature side in aortic cross-section (all P < 0.001). Multivariate analysis showed that tear size, the presence of re-entry and tear position anterior to the greater curvature were independent predictors of a patent false lumen.

CONCLUSIONS

In acute type A aortic dissection, larger tear size, the presence of re-entry and tear position anterior to the greater curvature are risk factors for a patent false lumen. Although the results of this study are valid only for patients in whom intimal tears were detected during aortic surgery, this trend may provide information for pathophysiology of the disease.

Risk factors for early death after surgery in patients with acute Stanford type A aortic dissection: A systematic review and meta-analysis

BACKGROUND

There are many risk factors related to early death after surgery among patients with acute Stanford type A aortic dissection (ATAAD) that have been analyzed in previous studies, but no evidence-based study has been conducted to confirm these risk factors.

AIMS

The aims of this study were to investigate risk factors for early death after surgery in patients with ATAAD via systematic review and meta-analysis and assess evidence-based strategies for preventing adverse events.

METHODS

The protocol for this study was prospectively registered with PROSPERO (CRD 42022332772). The authors systematically searched PubMed, Ovid, Scopus, Web of Science and Cochrane Library following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines from database construction to May 2021. Studies that met the selection criteria were determined by two independent researchers, and the odds ratios (ORs) and 95% confidence intervals (95% CIs) were reported for the risk factors and were pooled using Stata 15.0.

RESULTS

A total of 23 studies including 5510 patients met the inclusion criteria, and 10 risk factors were analyzed in this meta-analysis. The preoperative risk factors for early death after surgery in patients with ATAAD were age [(OR: 1.03, 95% CI (1.01, 1.06)], male sex [(OR: 1.43, 95% CI (1.06, 1.92)], shock [(OR: 1.91, 95% CI (1.06, 3.45)], malperfusion [(OR: 3.45, 95% CI (2.24, 5.31)] and cardiac tamponade [(OR: 3.89, 95% CI (1.17, 12.98)].

CONCLUSION

Patients with ATAAD who have an older age, male sex, shock, malperfusion and cardiac tamponade have a higher risk for early death after surgery. However, more highly homogenous studies are needed to demonstrate these results. Clinical staff should pay more attention to these factors and take individual actions to reduce mortality after surgery in patients with ATAAD.

On vasa vasorum: A history of advances in understanding the vessels of vessels

The vasa vasorum are a vital microvascular network supporting the outer wall of larger blood vessels. Although these dynamic microvessels have been studied for centuries, the importance and impact of their functions in vascular health and disease are not yet fully realized. There is now rich knowledge regarding what local progenitor cell populations comprise and cohabitate with the vasa vasorum and how they might contribute to physiological and pathological changes in the network or its expansion via angiogenesis or vasculogenesis. Evidence of whether vasa vasorum remodeling incites or governs disease progression or is a consequence of cardiovascular pathologies remains limited. Recent advances in vasa vasorum imaging for understanding cardiovascular disease severity and pathophysiology open the door for theranostic opportunities. Approaches that strive to control angiogenesis and vasculogenesis potentiate mitigation of vasa vasorum-mediated contributions to cardiovascular diseases and emerging diseases involving the microcirculation.

Management of Lower Limb Ischemia During Operative Repair of Acute Type A Aortic Dissection by Distal Crossover Grafts: a Case Series

Objective

To describe our experience of nine patients with extra-anatomical bypass for clinically ischemic distal limb during repair of acute Type A aortic dissection (ATAAD).

Methods

We retrospectively examined a series of nine patients who underwent surgery for ATAAD. We identified a subset of the patients who presented with concomitant radiographic and clinical signs of lower limb ischemia. All but one patient (axillobifemoral bypass) underwent femorofemoral crossover grafting by the cardiac surgeon during cooling.

Results

One hundred eighty-one cases of ATAAD underwent surgery during the study period with a mortality of 19.3%. Nine patients had persistent clinical evidence of lower limb ischemia (4.9%) and underwent extra-anatomical bypass during cooling. Two patients underwent additional fasciotomies. Mean delay from symptoms to surgery in these nine patients was 9.5 hours. Two patients had bilateral amputations despite revascularisation and, of note, had long delays in presentation for surgery (> 12 hours). There were no mortalities during these inpatient episodes. Outpatient radiographic follow-up at the first opportunity demonstrated 100% patency.

Conclusion

Our experience suggests that, during complicated aortic dissection, limb ischemia may have a devastating outcome including amputation when diagnosis and referral are delayed. Early diagnosis and surgery are crucial in preventing this potentially devastating complication.

Role of proximal and distal tear size ratio in hemodynamic change of acute type A aortic dissection

Background

Acute type A aortic dissection (ATAAD) is a life-threatening disease. The aim of this study was to examine the role of tear size in the hemodynamic change and help improve the treatment level of this extremely dangerous disease.

Methods

A total of 120 ATAAD patients treated in our institution from November 2014 to December 2016 were divided into three groups according to proximal and distal tear size ratio (PDTSR). There were 35 patients in group A (PDTSR ≥2:1), 44 patients in group B (1:2< PDTSR <2:1), and 41 patients in Group C (PDTSR ≤1:2). Three computational fluid dynamics (CFD) models with different PDTSRs were established to investigate the hemodynamic difference in the three groups.

Results

The mean age (± SD) of the 120 patients included in this study was 47.7±10.1 years. Patients in Group A had a significantly larger proximal tear size (219.1±76.5 vs. 127.7±70.1 vs. 75.7±49.7 mm²; P<0.001). The mortality of the patients in group A was significantly higher than those in group B and group C in the acute phase (37.1% vs. 2.3% vs. 2.4%, respectively; P<0.001). A proximal tear larger than a distal tear was found to be significantly associated with preoperative death in logistic regression analysis (odds ratio: 15.89; 95% confidence interval, 2.702-93.477; P=0.002).

Conclusions

A proximal tear larger than a distal tear was associated with a significantly high-pressure difference between false and true lumens and more blood flow into the false lumen. In such cases, patients would experience extremely high mortality and morbidity.