Ascending aorta dilatation in aortic valve disease: morphological analysis of medial changes

Medial degeneration and atherosclerosis show discrete variance around the circumference of ascending aorta aneurysms

Medial degeneration is the most common histological finding in ascending aortic aneurysms with lesser but significant involvement by atherosclerosis. The overall extent and severity can be potentially underrated because of their uneven distribution and macroscopic inconspicuousness of medial degeneration. This study aims to compare the distribution of degenerative and atherosclerotic lesions around ascending aorta circumference, also considering aortic valve cuspidity. We evaluated 88 cases of resected ascending aortae, 25 with a tricuspid aortic valve and 63 with a malformed aortic valve, oriented by a cardiac surgeon and sent for pathological examination. We applied the consensus documents from 2015 and 2016 for microscopic evaluation of aortic specimens. The medial degeneration and atherosclerosis were graded semi-quantitatively for each aortic quadrant: convexity, anterior wall, concavity, and posterior wall. Nearly all quadrants showed at least mild medial degeneration; more severe findings of medial degeneration and atherosclerosis were in the aneurysms associated with the tricuspid valve. In the aneurysms with the tricuspid aortic valve, there was more frequent and more severe atherosclerosis at the concavity than at the anterior wall (p = .046); the frequency and severity of medial degeneration did not differ significantly. The aneurysms with a malformed aortic valve showed more severe medial degeneration at the concavity compared to the convexity (p = .011); atherosclerosis was less common and did not show any significant differences. More than half of the samples also revealed at least a one-grade (mostly one-grade) difference among the quadrants in individual cases for both atherosclerosis and medial degeneration. Extreme differences were rare except for atherosclerosis in the tricuspid group. The results revealed only slight overall differences around the aortic circumference, with concavity being the most susceptible. Still, thanks to occurring inter- and intraindividual variability, the examination of all quadrants seems meaningful not to miss the most severe changes and to underscore the findings.

Synthesis of multidimensional pathophysiological process leading to type A aortic dissection: a narrative review

Objective

This review aims to synthesize the existing knowledge on the etiological process leading to type A aortic dissection (TAAD) and to clarify the relationship between mechanical, biochemical, and histopathological processes behind the aortic disease.

Background

Extensive research has previously identified several risk factors for TAAD as well as pathological mechanisms leading to TAAD. However, due to the complexity of the pathological process and limited knowledge on the relationships between distinct pathomechanisms leading to TAAD, the ability to identify the patients at high risk for TAAD has been poor.

Methods

PubMed (National Library of Medicine) database was searched for suitable literature. The most relevant articles focusing on anatomy, histopathology, physiology, and mechanics of ascending aorta and aortic diseases were reviewed.

Conclusions

Pathophysiology of the TAAD is related to biochemical and histological as well as mechanical and hemodynamic alterations leading to a degeneration of the aortic wall via inflammatory response. The degradative mechanisms of aortic wall structures and the mechanical forces, to which the wall is predisposed, are interrelated and influence one another. The relativity between the factors influencing aortic wall strength and healing capacity, and factors influencing mechanical stress on the aortic wall suggest that the risk of TAAD is not a linear but rather a dynamic phenomenon. Accounting for the dynamical property of the aortic disease in assessing the need for preventive surgical aortic reconstruction may provide a wider perspective in identifying patients at risk of TAAD and in planning preventive medical therapies.

Histopathological changes in dilated ascending aorta associated with aortic valve cuspidity

OBJECTIVES

Patients with a bicuspid aortic valve (BAV) often present with a dilated ascending aorta. However, the underlying pathogenesis for the observed changes in the aortic wall and the resulting aneurysmal dilation remains a subject of debate. This study aims to compare the histological abnormalities of the ascending aorta in BAV and tricuspid aortic valve (TAV) patients and their correlation with aortic diameter and patient age.

METHODS

A total of 376 patients from our institution's clinical database were included in the retrospective analysis. These patients underwent either elective surgery for ascending aorta dilation or emergency surgery for aortic dissection, either isolated or with a structurally diseased aortic valve. After excision, the ascending aorta samples were analysed by a pathologist.

RESULTS

On histological examination, a higher degree of elastic fibre fragmentation and loss and mucoid extracellular matrix accumulation was present in the samples from TAV patients when compared with that from BAV patients (P < 0.001). However, correlation was poor for all variables when considering aortic diameter and histological abnormalities or age and histological abnormalities in both BAV and TAV patients.

CONCLUSIONS

Our study demonstrates a greater incidence of severe histological abnormalities in TAV patients when compared with BAV patients.

Evaluation of the Effects of Mesoglycan on Some Markers of Endothelial Damage and Walking Distance in Diabetic Patients with Peripheral Arterial Disease

The aim of this study was to evaluate the variation of some parameters involved in peripheral artery disease progression in diabetic patients with peripheral artery disease after six months of mesoglycan. We enrolled 64 Caucasian, type 2 diabetic patients, with stage IIa peripheral artery disease. They were randomized to mesoglycan (Prisma^®), 50 mg twice a day, or placebo, for six months. We evaluated: glycemic control, metalloproteinase-2, and -9 (MMP-2, and -9), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion protein-1 (sVCAM-1), interleukin-6 (IL-6), soluble E-selectin (sE-selectin), high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), and plasminogen activator inhibitor-1 (PAI-1). We recorded a decrease of MMP-2, MMP-9, sE-selectin, TNF-α, sVCAM-1, and IL-6 compared to baseline, and to placebo in the group treated with mesoglycan. Regarding sICAM-1, and hs-CRP, instead, we recorded a decrease with mesoglycan only compared to baseline. Preliminary results seem to suggest an improvement of pain free walking distance with mesoglycan in 18 patients both compared to baseline and to placebo, even if data should be taken cautiously. Our study showed that supplementation with mesoglycan improved endothelial dysfunction in type 2 diabetic patients with peripheral artery disease. Regarding the preliminary data suggesting also a slight improvement of clinical parameters such as pain free walking distance, more data and a bigger sample of patients are necessary to better verify this aspect.

Using The Descending Aortic Wall Thickness Measured In Transesophageal Echocardiography As A Risk Marker For Aortic Dissection

OBJECTIVE

The aim of this study is to estimate whether aortic wall thickness is increased in patients with Aortic dissection (AD) compared to low risk control group and can be used in addition to aortic diameter as a risk marker of AD.

BACKGROUND

AD occurs due to pathologies that may increase thickness of the aortic wall. Transesophageal echocardiography (TEE) has the ability to visualize both the thoracic aortic wall and lumen. Aortic diameter has been used to predict aortic dissection and timing of surgery, but it is not always predictive of that risk.

METHODS

In 48 patients with AD who underwent TEE were examined retrospectively and compared to 48 control patients with patent foramen ovale (PFO). We measured aortic diameter at different levels, intimal/medial thickness (IMT) and complete wall thickness (CMT). Demographic data and cardiovascular risk factors were reviewed. The data was analyzed using ANOVA and student t test.

RESULTS

(AD) patients were older [mean age 66 AD vs. 51 PFO], had more hypertension, diabetes, hyperlipidemia and Coronary artery disease. Both IMT and CMT in the descending aorta were increased in AD group [(1.85 vs. 1.43 mm; P=0.03 and 2.93 vs. 2.46 mm; p=0.01). As expected the diameter of ascending aorta was also greater in AD (4.61 vs. 2.92 cm; P=0.004).

CONCLUSIONS

CMT and IMT in the descending aorta detected by TEE is greater in patients with AD when compared to control and may add prognostic data to that of aortic diameter.

Biomechanical characterization of ascending aortic aneurysm with concomitant bicuspid aortic valve and bovine aortic arch

Studies have shown that patients harboring bicuspid aortic valve (BAV) or bovine aortic arch (BAA) are more likely than the general population to develop ascending aortic aneurysm (AsAA). A thorough quantification of the AsAA tissue properties for these patient groups may offer insights into the underlying mechanisms of AsAA development. Thus, the objective of this study was to investigate and compare the mechanical and microstructural properties of aortic tissues from AsAA patients with and without concomitant BAV or BAA. AsAA (n=20), BAV (n=20) and BAA (n=15) human tissues were obtained from patients who underwent elective AsAA surgery. Planar biaxial and uniaxial failure tests were used to characterize the mechanical and failure properties of the tissues, respectively. Histological analysis was performed to detect medial degenerative characteristics of aortic aneurysm. Individual layer thickness and composition were quantified for each patient group. The circumferential stress-strain response of the BAV samples was stiffer than both AsAA (p=0.473) and BAA (p=0.152) tissues at a low load. The BAV samples were nearly isotropic, while AsAA and BAA samples were anisotropic. The areal strain of BAV samples was significantly less than that of AsAA (p=0.041) and BAA (p=0.004) samples at a low load. The BAA samples were similar to the AsAA samples in both mechanical and failure properties. On the microstructural level, all samples displayed moderate medial degeneration, characterized by elastin fragmentation, cell loss, mucoid accumulation and fibrosis. The ultimate tensile strength of BAV and BAA sampleswere also found to decrease with age. Overall, the BAV samples were stiffer than both AsAA and BAA samples, and the BAA samples were similar to the AsAA samples. The BAV samples were thinnest, with less elastin than AsAA and BAA samples, which may be attributed to the loss of extensibility of these tissues at a low load. No apparent difference in failure mechanics among the tissue groups suggests that each of the patient groups may have a similar risk of rupture.

Deep white matter hyperintensities, decreased serum low-density lipoprotein, and dilative large arteriopathy

Deep white matter hyperintensities (DWMHs) seen on magnetic resonance imaging (MRI) are thought to reflect small-vessel diseases (SVDs) and may have a background that differs from that of stenotic large-vessel diseases. We assessed risk factors for DWMHs and investigated the association between DWMHs and dilative changes in the basilar artery (BA) on MRI in nonstroke patients. We reviewed clinical information and MRI findings for 149 outpatients aged 46-90 years, excluding those with a previous symptomatic cerebrovascular event. DWMHs were graded 0-3, and the maximal BA diameter and area were measured from the flow void on axial T2-weighted MRI to assess dilatation. We divided the patients into groups with and without DWMH grade 2 or 3, and compared clinical information and BA parameters in these groups. The two groups demonstrated significant differences in age, serum low-density lipoprotein (LDL) level, estimated glomerular filtration rate (eGFR), and BA parameters. An adjusted logistic regression analysis including BA diameter found that age (odds ratio [OR], 1.974 per 10 years; 95% confidence interval [CI], 1.030-1.112; P = .0006), LDL (OR, 0.811 per 10 mg/dL; 95% CI, 0.964-0.965; P = .0085), eGFR (OR, 0.835 per 10 mL/min/1.73 m(2); 95% CI, 0.967-0.998; P = .0229), and BA diameter (OR, 2.515 per 1 mm; 95% CI, 1.191-4.098; P = .0119) were independently associated with the presence of DWMHs. An analysis including the BA area yielded similar results. DWMHs are manifestations of SVDs and show a strong association with lower serum LDL level, lower eGFR, and BA dilatation.

Alterations in aortic cellular constituents during thoracic aortic aneurysm development: myofibroblast-mediated vascular remodeling

The present study tested the hypothesis that changes in the resident endogenous cellular population accompany alterations in aortic collagen and elastin content during thoracic aortic aneurysm (TAA) development in a murine model. Descending thoracic aortas were analyzed at various time points (2, 4, 8, and 16 weeks) post-TAA induction (0.5 M CaCl2, 15 minutes). Aortic tissue sections were subjected to histological staining and morphometric analysis for collagen and elastin, as well as immunostaining for cell-type-specific markers to quantify fibroblasts, myofibroblasts, and smooth-muscle cells. Results were compared with reference control mice processed in the same fashion. Aortic dilatation was accompanied by changes in the elastic architecture that included: a decreased number of elastic lamellae (from 6 to 4); altered area fraction of elastin (elevated at 4 weeks and decreased at 16 weeks); and a decreased area between elastic lamellae (minimum reached at 4 weeks). Total collagen content did not change over time. Increased immunoreactivity for fibroblast and myofibroblast markers was observed at 8- and 16-week post-TAA-induction, whereas immunoreactivity for smooth-muscle cell markers peaked at 4 weeks and returned to baseline by 16 weeks. Therefore, this study demonstrated that changes in aortic elastin content were accompanied by the emergence of a subset of fibroblast-derived myofibroblasts whose altered phenotype may play a significant role in TAA development through the enhancement of extracellular matrix proteolysis.

Ventricular energetics in aortic root replacement for annuloaortic ectasia with aortic regurgitation

Aortic root replacement (Bentall operation) is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. We analyzed the mid-term results for left ventricular energetics after the Bentall operation for annuloaortic ectasia with aortic regurgitation. We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on transthoracic echocardiography data before, after, and approximately 1 year after the Bentall operation in 15 patients with annuloaortic ectasia with aortic regurgitation. Left ventricular volume was calculated by the Teichholz M-mode method. Ees and Ea were approximated as follows: Ees=mean blood pressure/minimal left ventricular volume, and Ea=systolic blood pressure/(maximal left ventricular volume--minimal left ventricular volume). Ea/Ees and SW/PVA were then calculated. Left ventricular volume was normalized with body surface area. Ees increased after the Bentall operation and around 1 year later (from 2.17+/-1.09 to 3.92+/-2.26 and 5.33+/-1.90 mmHg x m(2)/ml, P<0.001), thus resulting in an improvement in SW/PVA (from 68.8+/-8.2 to 70.9+/-9.5 and 74.7+/-5.2%, P=0.045). Ea also increased after the Bentall operation and 1 year later (from 1.77+/-0.61 to 2.88+/-1.28 and 3.54+/-1.43 mmHg x m(2)/ml, P<0.001). The mid-term results for ventricular contractility and efficiency after the Bentall operation for annuloaortic ectasia with aortic regurgitation are excellent and satisfactory.

[Pathobiology of idiopathic ascending aortic aneurysms]

BACKGROUND

The majority of ascending aortic aneurysms cannot be related to any specific etiology and should be qualified as idiopathic. The incidence of this disease is increasing in the population of the developed countries but its pathobiology is poorly understood.

AIM

This article is reviewing the publications concerning the pathobiology of idiopathic ascending aortic aneurysms.

SOURCES

A PubMed search on articles published in English or French, between January 1965 and December 2007, on key-words << aortic root >>, << ascending aorta >>, << aortic arch >>, << thoracic aorta >>, << aneurysm >>, << dilatation >> and << dissection >> was undertaken. Articles on aneurysms related to inflammatory and infectious diseases, congenital or genetic syndromes were excluded.

RESULTS

The presented data suggests that destructive remodeling of the aortic wall, inflammation and angiogenesis, biomechanical wall stress, and molecular genetics are relevant mechanisms of idiopathic ascending aortic aneurysm formation and progression.

LIMITS

Sparse data available from few direct studies offer limited knowledge on pathobiology of idiopathic ascending aortic aneurysms.

CONCLUSION

A more intimate knowledge of the triggers and perpetrating factors of this disease might offer new diagnostic and treatment options.

Perioperative results of the aortic root replacement in strict graft inclusion technique

BACKGROUND AND AIM

Bleeding may sometimes be a serious problem after the termination of the aortic root replacement. Therefore, the strict graft inclusion technique has been developed to avoid major complications. We present the early results after aortic root replacement in strict graft inclusion technique.

MATERIALS AND METHODS

The strict graft inclusion technique was performed in 28 patients between April 2001 and June 2006 in St-Johannes-Hospital-Dortmund, Dortmund, Germany. There were nine female and 19 male patients. The mean age was 57.78 +/- 12.01 years (28 to 77 years). A type A aortic dissection and an ascending aortic aneurysm with aortic valve lesion were the indication to operation in patients.

RESULTS

There were no early mortality and postoperative rethoracotomy. The mean postoperative bleeding over mediastinal drains was 565 +/- 310 mL. (100-2250 mL). In exception of the patients with preoperative double thrombocyte aggregation inhibitors therapy and postoperative consumption coagulopathy, the mean postoperative bleeding over mediastinal drain was 443.04 +/- 171.59 mL (100-1100) in the first 24 hours, the transfusion rate was minimal, mean 0.39 +/- 0.64 packed red blood cells (RBC) (0-4) and mean 0.14 +/- 0.27 packed fresh frozen plasma (FFP) (0-4), whereas only in 18 patients (78.26%) out of 23 patients was a transfusion not necessary. The intraoperative and postoperative requirement for substitution of erythrocyte concentrate was mean 1 +/- 1.28 packed RBC (0-5) and FFP concentrate was mean 1.21 +/- 1.90 packed FFP (0-12).

CONCLUSIONS

The strict graft inclusion technique for aortic root replacement represents a safe and feasible method to avoid bleeding from coronary ostial anastomoses, from aortic annular suture lines, and annular leak.

Sudden death due to aortic rupture in acromegaly

Acromegaly, when left untreated, is associated with premature mortality which is chiefly related to cardiovascular complications. We report on a 50-year-old acromegalic woman, resistant to therapy, who died suddenly because of thoracic aortic rupture and massive bleeding into the left pleural space. The postmortem examination disclosed, nearby the point of rupture, a pulmonary abscess as well as extensive intrinsic alteration of arteries originating from the aortic arch and aorta itself, which featured microscopic cystic medial necrosis. We discussed how these aspects could be related to long-term exposition to growth hormone excess. In particular, this case gives further evidence of vascular system frailty in acromegaly.

Unicuspid aortic valve mimicking quadricuspid valve

Unicuspid aortic valve is a rare congenital cardiac abnormality, leading to aortic stenosis or regurgitation. We report the case of a 55-year-old man with severe aortic regurgitation caused by a unicuspid valve mimicking quadricuspid valve.

Is size-reducing ascending aortoplasty with external reinforcement an option in modern aortic surgery?

OBJECTIVE

Enlargement of the ascending aorta is often combined with valvular, coronary, or other cardiac diseases. Reduction aortoplasty can be an optional therapy; however, indications regarding the diameter of aorta, the history of dilatation (poststenosis, bicuspid aortic valve), or the intraoperative management (wall excision, reduction suture, external reinforcement) are not established.

METHODS

In a retrospective study between 1997 and 2005, we investigated 531 patients operated for aneurysm or ectasia of the ascending aorta (diameter: 45-76mm). Of these, in 50 patients, size-reducing ascending aortoplasty was performed. External reinforcement with a non-coated dacron prosthesis was added in order to stabilize the aortic wall.

RESULTS

Aortoplasty was associated with aortic valve replacement in 47 cases (35 mechanical vs 12 biological), subvalvular myectomy in 29 cases, and CABG in 13 cases. The procedure was performed with low hospital mortality (2%) and a low postoperative morbidity. Computertomographic and echocardiographic diameters were significantly smaller after reduction (55.8+/-9mm down to 40.51+/-6.2mm (CT), p<0.002; 54.1+/-6.7mm preoperatively down to 38.7+/-7.1mm (echocardiography), p<0.002), with stable performance in long-term follow-up (mean follow-up time: 70 months).

CONCLUSIONS

As demonstrated in this study, size reduction of the ascending aorta using aortoplasty with external reinforcement is a safe procedure with excellent long-term results. It is a therapeutic option in modern aortic surgery in patients with poststenotic dilatation of the aorta without impairment of the sinotubular junction of the aortic valve and root.