Retrograde dye perfusion of the proximal aorta - A postmortem technical study

Introduction

Multiple cardiovascular conditions can lead to unexpected fatality, which is defined as sudden cardiac death. One of these potentially underlying conditions is aortic regurgitation, which can be caused by discrete changes of the geometry of the proximal aorta. To analyze aortic valve competency and furthermore to elucidate underlying pathological alterations of the coronary arteries and the vasa vasorum a perfusion method to simulate a diastolic state was designed.

Material and methods

A postmortem approach with retrograde perfusion of the ascending aorta with methylene blue was applied to three bodies. The procedure comprised cannulation of the brachiocephalic trunk, clamping of the aortic arch between brachiocephalic trunk and left carotid artery, infusion of 250 ml of methylene blue, and optical clearing of the superficial tissue layers after perfusion. Organs were examined directly following perfusion and after optical clearing.

Results

Assessment and visualization of aortic valve competency and the vasa vasorum were possible in all three instances. Visualization of the coronary perfusion was impaired by postmortem thrombus formation. Optical clearing did not provide additional information.

Discussion

The method presented here is a time- and cost-efficient way of visualizing aortic valve competency and the vasa vasorum. The visualization of the vasa vasorum highlights the potential of this method in basic research on diseases of the great arteries and coronaries. However, for a time-efficient functional analysis of the coronaries, other methods must be applied.

Optical coherence tomography of the pulmonary arteries in children with congenital heart diseases: A systematic review

Importance

Optical coherence tomography (OCT) is a high-resolution intravascular imaging tool and has shown promise for providing real-time quantitative and qualitative descriptions of pulmonary vascular structures in vivo in adult pulmonary hypertension (PH), while not popular in pediatric patients with congenital heart diseases (CHD).

Objective

The aim of this review is to summarize all the available evidence on the use of OCT for imaging pulmonary vascular remodeling in pediatric patients.

Methods

We conducted the systematic literature resources (Cochran Library database, Medline via PubMed, EMBASE, and Web of Knowledge) from January 2010 to December 2021 and the search terms were "PH", "child", "children", "pediatric", "OCT", "CHD", "pulmonary vessels", "pulmonary artery wall". Studies in which OCT was used to image the pulmonary vessels in pediatric patients with CHD were considered for inclusion.

Results

Five studies met the inclusion criteria. These five papers discussed the study of OCT in the pulmonary vasculature of different types of CHD, including common simple CHD, complex cyanotic CHD, and Williams-Beuren syndrome. In biventricular anatomy, pulmonary vascular remodeling was primarily reflected by pulmonary intima thickening from two-dimensional OCT. In single-ventricle anatomy, due to the state of hypoxia, the morphology of pulmonary vessels was indirectly reflected by the number and shape of nourishing vessels from three-dimensional OCT.

Interpretation

OCT may be an adequate imaging procedure for the demonstration of pulmonary vascular structures and provide additional information in pediatric patients.

Three-dimensional imaging of pulmonary arterial vasa vasorum using optical coherence tomography in patients after bidirectional Glenn and Fontan procedures

AIMS

We evaluated pulmonary arterial (PA) vasa vasorum (VV) in Fontan candidate patients with a novel three-dimensional (3D) imaging technique using optical coherence tomography (OCT).

METHODS AND RESULTS

This prospective study assessed the development of adventitial VV in the distal PA of 10 patients with bidirectional Glenn circulation (BDG group, 1.6 ± 0.3 years) and Fontan circulation (Fontan group, 3.3 ± 0.3 years), and in 20 children with normal PA haemodynamics and morphology (Control group, 1.5 ± 0.3 years). We assessed the PA VV with two-dimensional (2D) cross-sectional, multi-planar reconstruction (MPR), and volume rendering (VR) imaging. VV development was evaluated by the VV area/volume ratio, defined as the VV area/volume divided by the adventitial area/volume. Compared to the control group, the observed VV number and diameter on 3D images of MPR and VR were significantly higher, and curved and torturous-shaped VV were more frequently observed in the BDG and Fontan groups (P < 0.001, all). The median VV volume ratio was significantly greater in the BDG than in the control group (3.38% vs. 0.61%; P < 0.001). Although the VV volume ratio decreased significantly after the Fontan procedure (2.64%, P = 0.005 vs. BDG), the ratio remained higher than in the control group (P < 0.001 vs. control).

CONCLUSION

3D OCT imaging is a novel method that can be used to evaluate adventitial PA VV and may provide pathophysiological insight into the role of the PA VV in these patients.

Role of lipids and intraplaque hypoxia in the formation of neovascularization in atherosclerosis

According to the current paradigm, chronic vascular inflammation plays a central role in the pathogenesis of atherosclerosis. The plaque progression is typically completed with rupture and subsequent acute cardiovascular complications. Previously, the role of adventitial vasa vasorum in atherogenesis was underestimated. However, investigators then revealed that vasa vasorum neovascularization can be observed when no clinical manifestation of atherosclerosis is present. Vasa vasorum is involved in various proatherogenic processes such as intimal accumulation of inflammatory leukocytes, intimal thickening, necrotic core formation, intraplaque haemorrhage, lesion rupture and atherothrombosis. Due to the destabilizing action of the intraplaque microenvironment, lesional vasa vasorum neovessels experience serious defects and abnormalities during development that leads to their immaturity, fragility and leakage. Indeed, intraplaque neovessels are a main cause of intraplaque haemorrhage. Visualization techniques showed that presence of neovascularization/haemorrhage can serve as a good indicator of lesion instability and higher risk of rupture. Vasa vasorum density is a strong predictor of acute cardiovascular events such as sudden death, myocardial infarction and stroke. At present, arterial vasa vasorum neovascularization is under intensive investigation along with development of therapeutic tools focused on the control of formation of vasa vasorum neovessels in order to prevent plaque haemorrhage/rupture and thromboembolism. KEY MESSAGE Neovascularization plays an important role in atherosclerosis, being involved in unstable plaque formation. Presence of neovascularization and haemorrhage indicates plaque instability and risk of rupture. Various imaging techniques are available to study neovascularization.

Viewpoint: Recent Advances in Intracoronary Imaging for Vasa Vasorum Visualisation

The coronary adventitia harbours the vasa vasorum (VV), which has a diameter of 50-300 µm and plays an important role as a network of nutrient blood vessels to the arterial wall. The VV is thought to be involved in the development of coronary atherosclerosis. Recent advances in the field of intracoronary imaging, including optical coherence tomography, have enabled us to visualise coronary VV in humans in vivo and increased the clinical relevance of the VV in patients with coronary artery disease.

Association between coronary microvascular function and the vasa vasorum in patients with early coronary artery disease

BACKGROUND AND AIMS

The vasa vasorum (VV) plays a role in the initial phase of atherosclerosis, and abnormalities in microvascular function may be sensitive measures of the early development of atherosclerosis. The current study was designed to access the association between coronary microvascular function and VV density in patients undergoing cardiac catheterization.

METHODS

Twenty-four patients with early coronary artery disease underwent endothelium-dependent (coronary blood flow, CBF) and endothelium-independent (coronary flow velocity reserve, CFVR) coronary microvascular function testing, and optical coherence tomography (OCT) imaging of the left anterior descending coronary artery (LAD). Using an intracoronary Doppler guidewire, CBF was examined by evaluating changes in blood flow in response to acetylcholine and CFVR in response to adenosine. VV density (VV volume/vessel volume × 100, %VV) of the proximal 10 mm of the LAD was quantified by OCT.

RESULTS

The median values (Q1, Q3) of CFVR, % changes in CBF in response to acetylcholine, and the %VV were 2.70 (2.30, 2.90), -16.82 (-42.34, 54.52), and 2.62 (2.35, 3.35), respectively. %VV correlated inversely with CBF (r = -0.614, p = 0.001) and directly with CFVR (r = 0.423, p = 0.040). Multivariate analysis showed that only %VV was significantly correlated with CBF and the association was independent of other clinical variables, Framingham risk score, body mass index, and a family history of coronary heart disease.

CONCLUSIONS

This study demonstrates that VV density has negative correlation with endothelium-dependent microvascular function in patients with early coronary atherosclerosis. These observations link adventitial VV structure and function to microvascular dysfunction in early coronary atherosclerosis.