Arterial remodeling of the common carotid artery after aortic valve replacement in patients with aortic stenosis

Patients with aortic stenosis exhibit early improved endothelial function following transcatheter aortic valve replacement: The eFAST study

BACKGROUND

Patients with severe aortic stenosis (AS) exhibit systemic endothelial dysfunction, which can be associated with myocardial ischaemia in absence of obstructive coronary disease. Transcatheter aortic valve replacement (TAVR) is used to treat severe AS in patients with high or prohibitive surgical risk. However, it remains unknown whether endothelial function recovers post-TAVR. We therefore sought to assess the early and late changes in flow-mediated dilation (FMD), a measure of endothelial function, following TAVR.

METHODS

Patients undergoing TAVR for severe AS had ultrasound assessment of brachial endothelial-independent and -dependent FMD. Measurements were performed pre-TAVR, at early follow-up (<48 h post-TAVR) and late follow-up (4-6 weeks post-TAVR).

RESULTS

27 patients (mean age 82.0 ± 7.0; 33.3% female) were recruited; 37.0% had diabetes mellitus and 59.3% had hypertension. Brachial artery FMD increased from 4.2 ± 1.6% (pre-TAVR) to 9.7 ± 3.5% at early follow-up (p < 0.0001). At late follow-up, improvement compared with early follow-up was sustained (8.7 ± 1.9%, p = 0.27). Resting brachial arterial flow velocities decreased significantly at late follow-up (11.24 ± 5.16 vs. 7.73 ± 2.79 cm/s, p = 0.003). Concordantly, at late follow-up, there was decrease in resting wall shear stress (WSS; 14.8 ± 7.8 vs. 10.6 ± 4.8dyne/cm2, p = 0.01), peak WSS (73.1 ± 34.1 vs. 58.8 ± 27.8dyne/cm2, p = 0.03) and cumulative WSS (3543 ± 1852 vs. 2504 ± 1089dyne·s/cm², p = 0.002). Additionally, a favourable inverse correlation between cumulative WSS and FMD was restored at late follow-up (r = -0.21 vs. r = 0.49).

CONCLUSION

Endothelial function in patients with AS improves early post-TAVR and this improvement is sustained. This likely occurs as a result of improved arterial haemodynamics, leading to lower localised WSS and release of vasoactive mediators that may also alleviate myocardial ischaemia.

Exercise SBP response and incident depressive symptoms: The Maastricht Study

OBJECTIVE

: An exaggerated exercise SBP, which is potentially modifiable, may be associated with incident depressive symptoms via an increased pulsatile pressure load on the brain. However, the association between exaggerated exercise SBP and incident depressive symptoms is unknown. Therefore, we examined whether exaggerated exercise SBP is associated with a higher risk of depressive symptoms over time.

METHODS

: We used longitudinal data from the population-based Maastricht Study, with only individuals free of depressive symptoms at baseline included (n = 2121; 51.3% men; age 59.5 ± 8.5 years). Exercise SBP was measured at baseline with a submaximal exercise cycle test. We calculated a composite score of exercise SBP based on four standardized exercise SBP measures: SBP at moderate workload, SBP at peak exercise, SBP change per minute during exercise and SBP 4 min after exercise. Clinically relevant depressive symptoms were determined annually at follow-up and defined as a Patient Health Questionnaire score of at least 10.

RESULTS

: After a mean follow-up of 3.9 years, 175 participants (8.3%) had incident clinically relevant depressive symptoms. A 1 SD higher exercise SBP composite score was associated with a higher incidence of clinically relevant depressive symptoms [hazard ratio: 1.27 (95% confidence interval: 1.04-1.54)]. Results were adjusted for age, sex, education level, glucose metabolism status, lifestyle, cardiovascular risk factors, resting SBP and cardiorespiratory fitness.

CONCLUSION

: A higher exercise SBP response is associated with a higher incidence of clinically relevant depressive symptoms.

Infrahyoid wandering carotid arteries

Knowledge of retropharyngeal carotid arteries in patients is important in order to avoid potential catastrophic injuries. Previous studies demonstrated that carotid arteries can change in position at or near the level of the hyoid bone on serial scans. We report the presence of wandering carotid arteries at the level of the cricoid cartilage and superiorly in the neck of a 74-year-old female patient over multiple months. The potential for carotid arteries to randomly change positions in the suprahyoid and infrahyoid neck should be known by clinicians to avoid misdiagnosing occult neck masses and to avoid potential arterial injury during neck surgery. Although the exact etiology for wandering carotid arteries remains uncertain, we propose that reduced axial tension on carotid arteries and increased body mass Index may play a causative role.

Empagliflozin influences blood viscosity and wall shear stress in subjects with type 2 diabetes mellitus compared with incretin-based therapy

Background

Cardiovascular protection following empagliflozin therapy is not entirely attributable to the glucose lowering effect. Increased hematocrit might influence the shear stress that is the main force acting on the endothelium, regulating its anti-atherogenic function.

Objective

We designed the study with the aim of investigating the effect of empagliflozin on blood viscosity and shear stress in the carotid arteries. A secondary endpoint was the effect of empagliflozin on carotid artery wall thickness.

Methods

The study was a non-randomized, open, prospective cohort study including 35 type 2 diabetic outpatients who were offered empagliflozin or incretin-based therapy (7 liraglutide, 8 sitagliptin) in combination with insulin and metformin. Blood viscosity, shear stress and carotid wall thickness were measured at baseline and at 1 and 3 months of treatment. Blood viscosity was measured with a viscometer, and shear stress was calculated using a validated formula. Intima-media thickness (IMT) of the carotid artery was detected by ultrasound and was measured with dedicated software.

Results

Blood viscosity (4.87 ± 0.57 vs 5.32 ± 0.66 cP, p < 0.02) and shear stress significantly increased in the Empagliflozin group while no change was detected in the Control group (4.66 ± 0.56 vs 4.98 ± 0.73 cP, p = NS). IMT significantly decreased in the Empagliflozin group after 1 and 3 months (baseline: 831 ± 156, 1-month 793 ± 150, 3-month 766 ± 127 μm; p < 0.0001), while in the liraglutide group, IMT significantly decreased only after 3 months (baseline 879 ± 120; 1-month 861 ± 163; 3-month 802 ± 114 μm; p < 0.001). In the sitagliptin group, IMT remained almost unchanged (baseline 901 ± 135; 1-month 902 ± 129; 3-month 880 ± 140 μm; p = NS).

Conclusions

This study is the first to describe a direct effect of empagliflozin on blood viscosity and wall shear stress. Furthermore, IMT was markedly reduced early on in the Empagliflozin group.

Carotid Doppler sonography: additional tool to assess hemodynamic improvement after transcatheter aortic valve implantation

PURPOSE

The aim of our study was to assess the arterial cerebral blood flow variations in patients with aortic valve stenosis, immediately after the transcatheter aortic valve implantation (TAVI).

METHODS

The study population includes 62 consecutive patients who underwent TAVI for aortic valve stenosis (95%) and sugical bioprosthesis degeneration (5%). Carotid Doppler examination was performed recording blood flow, systolic peak velocity, time average mean velocity and mean acceleration time at baseline, after balloon aortic valvuloplasty, and within 10 min after the device release.

RESULTS

A significant improvement of blood flow was recorded at the end of the procedure (from 315.05 ± 141.72 to 538.67 ± 277.46 ml/min; P < 0.00001). The systolic peak velocity and the time average mean velocity increased from 52.27 ± 14.29 to 78.89 ± 20.48 cm/s (P < 0.00001) and from 12.24 ± 4.74 to 21.21 ± 9 cm/s (P < 0.00001), respectively. Consensually, the mean acceleration time decreased from 0.22 ± 0.02 to 0.03 ± 0.02 s (P < 0.00001) after the procedure.

CONCLUSION

Monitoring of Doppler measurements may be a useful and noninvasive method to assess acutely the improvement of hemodynamic flow after TAVI, specifically for the cerebral district.

Aortic versus carotid intima-media thickness and impact of aortic valve disease

BACKGROUND AND AIMS

Intima-media thickness is a marker for atherosclerosis but is also influenced by shear stress and flow. We evaluated the relation between intima-media thickness of the descending aorta (AoIMT) and the common carotid artery (CIMT) in patients with and without severe aortic valve disease (sAVD).

METHODS

A total of 310 patients (233 with sAVD, 77 without) were examined with regard to AoIMT and CIMT using transesophageal echocardiography and carotid ultrasound, respectively, before valvular and/or aortic surgery. Digitally stored B-mode images were used for semiautomatic AoIMT and CIMT measurements.

RESULTS

There were no significant differences in patients with or without sAVD with regard to AoIMT (1·35 ± 0·31 vs. 1·35 ± 0·33 mm) or CIMT (0·80 ± 0·15 vs. 0·78 ± 0·16 mm). The correlations between AoIMT and CIMT were r = 0·29 in patients with and r = 0·51 in patients without sAVD, and the difference between these correlations was significant (P<0·05). In multivariate regression, age was the main determinant for AoIMT and CIMT in both groups, further in sAVD, the aortic mean pressure gradient (P_mean ) was a determinant of AoIMT, but not of CIMT.

CONCLUSIONS

The correlation between CIMT and AoIMT is weaker in patients with sAVD compared to those without sAVD. P_mean is also a significant predictor of AoIMT, but not of CIMT. This implies that, in addition to the atherosclerotic process, turbulent aortic flow or altered blood flow helicity created by large stroke volumes and diastolic flow reversal or high-velocity jets, affect the intima-media of the descending aorta and common carotid artery differently.

Perioperative evaluation of regional aortic wall shear stress patterns in patients undergoing aortic valve and/or proximal thoracic aortic replacement

OBJECTIVES

To assess in patients with aortopathy perioperative changes in thoracic aortic wall shear stress (WSS), which is known to affect arterial remodeling, and the effects of specific surgical interventions.

METHODS

Presurgical and postsurgical aortic 4D flow MRI were performed in 33 patients with aortopathy (54 ± 14 years; 5 women; sinus of Valsalva (d_SOV)/midascending aortic (d_MAA) diameters = 44 ± 5/45 ± 6 mm) scheduled for aortic valve (AVR) and/or root (ARR) replacement. Control patients with aortopathy who did not have surgery were matched for age, sex, body size, and d_MAA (n = 20: 52 ± 14 years; 3 women; d_SOV/d_MAA = 42 ± 4/42 ± 4 mm). Regional aortic 3D systolic peak WSS was calculated. An atlas of WSS normal values was used to quantify the percentage of at-risk tissue area with abnormally high WSS, excluding the area to be resected/graft.

RESULTS

Peak WSS and at-risk area showed low interobserver variability (≤0.09 [-0.3; 0.5] Pa and 1.1% [-7%; 9%], respectively). In control patients, WSS was stable over time (follow-up-baseline differences ≤0.02 Pa and 0.0%, respectively). Proximal aortic WSS decreased after AVR (n = 5; peak WSS difference ≤-0.41 Pa and at-risk area ≤-10%, P < .05 vs controls). WSS was increased after ARR in regions distal to the graft (peak WSS difference ≥0.16 Pa and at-risk area ≥4%, P < .05 vs AVR). Follow-up duration had no significant effects on these WSS changes, except when comparing ascending aortic peak WSS between ARR and AVR (P = .006).

CONCLUSIONS

Serial perioperative 4D flow MRI investigations showed distinct patterns of postsurgical changes in aortic WSS, which included both reductions and translocations. Larger longitudinal studies are warranted to validate these findings with clinical outcomes and prediction of risk of future aortic events.

Pathobiology of Idiopathic Ascending Aortic Aneurysms

The majority of ascending aortic aneurysms cannot be related to any specific etiology and should be qualified as idiopathic. The pathobiology of ascending aortic aneurysms remains incompletely understood. Data from direct study are still scarce and often limited because of patient heterogenicity. Currently available information 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. Further understanding of these mechanisms will likely provide novel diagnostic, prognostic, and therapeutical tools for the clinician.

Sustained Elevation of Vascular Endothelial Growth Factor and Angiopoietin-2 Levels After Transcatheter Aortic Valve Replacement

BACKGROUND

Transcatheter aortic valve replacement (TAVR) exposes the systemic vasculature to increased mechanical forces. Endothelial adaptation to mechanical stimuli is associated with angiogenic activation through various growth factors. We studied the potential angiogenic shift evoked by TAVR.

METHODS

From a cohort of 69 consecutive patients undergoing TAVR, we excluded patients with conditions known to affect angiogenic factors, and serum vascular endothelial growth factor (VEGF) and angiopoietin (Ang)-1 and Ang-2 were assessed by ELISA. We assessed in vitro the properties of endothelial cells after exposure to serum collected from patients undergoing TAVR using adhesion, migration, and Matrigel angiogenesis assays. The correlation between changes in angiogenic factors and cardiac functions was evaluated on 30- day echocardiograms.

RESULTS

The study population consisted of 46 patients (82 ± 5 years). Two days after TAVR the post/pre TAVR ratio of VEGF, Ang-1, and Ang-2 was 5.38 ± 4 (P < 0.001), 1.05 ± 0.49 (P = 0.27), and 4.65 ± 2.01 (P < 0.001), respectively. The increase in VEGF and Ang-2 showed a significant correlation (r = 0.609; P < 0.001), but no correlation was found with hemolysis or tissue injury markers. Patients with relatively low levels of VEGF or an Ang-2 rise had more severe aortic stenosis and coronary disease at baseline. Exposure of endothelial cells to post-TAVR serum induced adhesion, migration, and tube formation compared with pre-TAVR serum. An increase in VEGF levels correlated with improvement in pulmonary systolic pressure and a right ventricular fractional area change at 30 days, (r = 0.54 and r = 0.48, respectively; P < 0.01).

CONCLUSIONS

Sustained elevation of VEGF and Ang-2 levels occur after TAVR, reflecting a systemic angiogenic shift. A rise in VEGF levels is associated with a decrease in pulmonary blood pressure in patients undergoing TAVR.

Computational study of pulsatile blood flow in prototype vessel geometries of coronary segments

The spatial and temporal distributions of wall shear stress (WSS) in prototype vessel geometries of coronary segments are investigated via numerical simulation, and the potential association with vascular disease and specifically atherosclerosis and plaque rupture is discussed. In particular, simulation results of WSS spatio-temporal distributions are presented for pulsatile, non-Newtonian blood flow conditions for: (a) curved pipes with different curvatures, and (b) bifurcating pipes with different branching angles and flow division. The effects of non-Newtonian flow on WSS (compared to Newtonian flow) are found to be small at Reynolds numbers representative of blood flow in coronary arteries. Specific preferential sites of average low WSS (and likely atherogenesis) were found at the outer regions of the bifurcating branches just after the bifurcation, and at the outer-entry and inner-exit flow regions of the curved vessel segment. The drop in WSS was more dramatic at the bifurcating vessel sites (less than 5% of the pre-bifurcation value). These sites were also near rapid gradients of WSS changes in space and time - a fact that increases the risk of rupture of plaque likely to develop at these sites. The time variation of the WSS spatial distributions was very rapid around the start and end of the systolic phase of the cardiac cycle, when strong fluctuations of intravascular pressure were also observed. These rapid and strong changes of WSS and pressure coincide temporally with the greatest flexion and mechanical stresses induced in the vessel wall by myocardial motion (ventricular contraction). The combination of these factors may increase the risk of plaque rupture and thrombus formation at these sites.

Sphygmomanometric and ambulatory blood pressures as forerunners of carotid and femoral intima-media thickness

OBJECTIVE

Studies directly comparing the associations of intima-media thickness with blood pressure (BP) on manual sphygmomanometric blood pressure measurement (SBPM) and 24-h ambulatory blood pressure measurement (ABPM) are scarce and have a cross-sectional design.

METHODS

At baseline, we measured systolic and diastolic blood pressures, pulse pressure, and mean arterial pressure in 532 randomly recruited patients (women, 48.3%; mean age, 38.9 years) by SBPM and ABPM. SBPM was the average of five consecutive readings obtained by trained observers at the patients' homes. We measured carotid intima-media thickness (CIMT) and femoral intima-media thickness (FIMT) by a wall-tracking ultrasound system, 26 months (median) after BP measurement (interquartile range, 21-29 months). We adjusted all analyses for observer, sex, age, BMI, smoking, and total/high-density lipoprotein-cholesterol ratio.

RESULTS

The multivariable-adjusted associations of CIMT and FIMT with all BP components on SBPM were not significant (P >or= 0.12). In multivariable-adjusted models, CIMT increased with 24-h systolic blood pressure (effect size per SD increase, +0.131 mm; P = 0.003) and 24-h pulse pressure (+0.139 mm; P = 0.001), whereas FIMT increased with 24-h diastolic blood pressure (+0.091 mm; P = 0.03) and 24-h mean arterial pressure (+0.090 mm; P = 0.04). Models including the ambulatory blood pressure components additionally adjusted for SBPM and more covariables than those listed above were confirmatory.

CONCLUSION

In a general population, BP on ABPM predicts CIMT and FIMT over and beyond highly standardized SBPM. At the elastic carotid artery, CIMT increased predominantly with the pulsatile component of BP, whereas at the muscular femoral artery, FIMT increased with the steady component of BP.

Conventional and 24-h ambulatory blood pressure as independent predictors of elastic arterial properties

OBJECTIVE

No population study investigated whether 24-h ambulatory blood pressure (ABP) predicts distensibility of the elastic common carotid (DCar) and the muscular femoral (DFem) arteries over and beyond conventionally measured blood pressure (CBP).

METHODS

At baseline, we measured CBP and 24-h ABP in 1063 randomly recruited participants (mean age, 44.3 years). CBP was the average of five consecutive readings obtained by trained observers at the participants' homes. We measured arterial distensibility by a wall-tracking ultrasound system, 21 months after CBP and ABP (5-95th percentile interval range, 13-33 months).

RESULTS

Compared with men, women (49.2%) had higher (P<0.03) DCar (24.7 vs. 23.3 x 10(-3)/kPa) and higher DFem (10.6 vs. 9.2 x 10(-3)/kPa). In multivariate-adjusted models, including both CBP and ABP and stratified by sex, DCar was negatively related to systolic, diastolic, and mean arterial CBP in both sexes, and to diastolic ABP in women. DFem was inversely correlated with diastolic ABP in both sexes and with systolic and mean arterial ABP in men. Moreover, DFem was also negatively correlated with systolic and mean arterial CBP in men. In most instances, pulse pressure on CBP or ABP measurement did not predict DCar or DFem. No evidence of influential collinearity between CBP and ABP was observed.

CONCLUSION

Depending on vascular territory, there is competition between highly standardized CBP and ABP in predicting DCar and DFem. These findings show that CBP under standardized conditions, and subject to rigorous quality control, is equally predictive of the elastic properties of large arteries as ABP.

[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.