Pulse pressure-driven neutral lipid accumulation and correlative proinflammatory markers of accelerated atherogenesis

Pulsatile Hemodynamics and Coronary Artery Disease

Coronary artery disease (CAD) is the leading cause of human death and has a high prevalence throughout the world. Therefore, it is important to detect CAD early and to apply individualized therapy according to the patients' risk. There is an increasing interest in pulsatile arterial hemodynamics in the cardiovascular area. Widely used measurements of arterial pulsatile hemodynamics include pulse pressure, pulse wave velocity and augmentation index. Here, we will review underlying pathophysiology linking the association of arterial pulsatile hemodynamics with CAD, and the usefulness of the measurements of pulsatile hemodynamics in the prediction of future cardiovascular events of CAD patients. Clinical and therapeutic implications will be also addressed.

Role of increased central arterial stiffness in macro and microvascular damage in patients with coronary artery disease

BACKGROUND

Patients with heart disease frequently have renal dysfunction manifested by a decrease in glomerular filtration rate (GFR) and / or increase of albuminuria.

OBJECTIVES

The objective was to study the possible role of increased aortic stiffness in the presence and extent of coronary artery disease (CAD) and kidney dysfunction in a group of patients with suspected CAD.

PATIENTS AND METHODS

We studied forty-eight patients undergoing coronariography for suspected coronary disease (CAD). Using applanation tonometry on the radial artery and applying a transfer function, central blood pressure values were calculated. The study of aortic stiffness was done by determining the carotid-femoral pulse velocity (Pv_c-f).

RESULTS

Of the 48 patients, 11 had no significant coronary lesions, 24 showed significant lesions in 1 or 2 coronary arteries and 13 in ≥ 3 arteries. The group with a higher degree of CD had significantly higher cPP values than the group without CD. The Pv_c-f increased progressively and significantly with the degree of CD. The logistic regression showed that Pv_c-f independently predicted the presence of CD. The relative risk of CD increased 2.5 times for each meter of increase in Pv_c-f. The GFR was negatively and significantly correlated with age and Pv_c-f was associated with albuminuria.

CONCLUSIONS

In patients with stable CD, Pv_c-f, expression of aortic stiffness, is independently associated with the existence of CD and its degree of extension. The increase in arterial stiffness also participates in the decrease in GFR and in the increase in albuminuria.

Good advice for endothelial cells: Get in line, relax tension, and go with the flow

Endothelial cells (ECs) are continuously subjected to fluid wall shear stress (WSS) and cyclic strain caused by pulsatile blood flow and pressure. It is well established that these hemodynamic forces each play important roles in vascular disease, but their combined effects are not well understood. ECs remodel in response to both WSS and cyclic strain to align along the vessel axis, but in areas prone to atherogenesis, such an alignment is absent. In this perspective, experimental and clinical findings will be reviewed, which have revealed the characteristics of WSS and cyclic strain, which are associated with atherosclerosis, spanning studies on whole blood vessels to individual cells to mechanosensing molecules. Examples are described regarding the use of computational modeling to elucidate the mechanisms by which EC alignment contributes to mechanical homeostasis. Finally, the need to move toward an integrated understanding of how hemodynamic forces influence EC mechanotransduction is presented, which holds the potential to move our currently fragmented understanding to a true appreciation of the role of mechanical stimuli in atherosclerosis.

Incidence of Peripheral Arterial Disease and Its Association with Pulse Pressure: A Prospective Cohort Study

BACKGROUND

The association of pulse pressure and peripheral arterial disease (PAD) has seldom been examined using a prospective design. This study aimed to investigate the association of pulse pressure with PAD incidence in an elderly general population.

METHODS

We utilized data from a cohort conducted in Beijing with additionally 2-year follow-up time. PAD was defined as an ankle brachial index value <0.9 in either leg. Cox proportional hazard regression model was used to quantify the magnitude of pulse pressure on PAD incidence.

RESULTS

During a 2-year follow-up time, 357 of 4,201 (8.5%) participants developed PAD with 105 (6.9%) men and 252 (9.4%) women, respectively. After adjusting for baseline age, sex, body mass index, hypertension, diabetes, total cholesterol, and high-density lipoprotein cholesterol, and smoking, the hazard ratio and 95% confidence interval for people with pulse pressure greater than 60 mmHg was 2.20 (1.53, 3.15) compared with those whose pulse pressure was less than 40 mmHg. A linear trend was observed for the association of pulse pressure with PAD.

CONCLUSION

Higher pulse pressure was associated with higher PAD incidence.

Early verification of myocardial ischemia with a novel biomarker of acute tissue damage: C-reactive protein fractional forms

BACKGROUND

We evaluated the utility of an independent biomarker of early ischemic cellular damage-circulating fractional forms of C-reactive protein (fracCRP), to verify the diagnostic relevance of low Troponin I (TnI) values within the context of a workup for Acute Coronary Syndrome (ACS).

METHODS

On a semi-preparative scale, the molecular characteristics of fracCRP were established by electron microscopy and Western Blot, using isolates captured from patient serum on phosphorylcholine beads and purified by size exclusion high-pressure liquid chromatography (SE-HPLC). Captured on an analytical scale, the diagnostic utility of fracCRP was evaluated in first-draw plasma specimens (total CRP not exceeding 6 mg/l) recovered from 300 cardiac emergency patients with final discharge diagnoses of ACS ruled out (N=132) or ruled in (N=168).

RESULTS

At a cutoff value chosen for 97.7% test specificity, the test metric (fracCRP×TnI) identified in the first blood draw 39.9% of all emergency patients ultimately diagnosed with ACS, and 17.9% of ultimately diagnosed patients who arrived with TnI values within the normal reference range (0.01-0.04 ng/ml).

CONCLUSIONS

These findings suggest that the fracCRP test metric could serve as a rule-in test for ACS in a significant proportion of low to moderate risk emergency patients.

Impaired fibrillin-1 function promotes features of plaque instability in apolipoprotein E-deficient mice

BACKGROUND

Arterial stiffness has been associated with an increased cardiovascular risk. The aim of this study was to investigate the interaction between arterial stiffness and atherosclerosis.

METHODS AND RESULTS

Mice with a mutation C1039G+/-) in the fibrillin-1 gene leading to fragmentation of the elastic fibers were crossbred with apolipoprotein E-deficient (ApoE-/-) mice. Subsequently, ApoE-/- and ApoE-/-C1039G+/- mice were fed a Western-type diet for 10 or 20 weeks. Our results show that the interaction between arterial stiffness and atherosclerosis is bidirectional. On the one hand, arterial stiffness in ApoE-/-C1039G+/- mice increased more rapidly in the presence of atherosclerotic plaques. On the other hand, arterial stiffness promoted the development of larger and more unstable plaques in ApoE-/-C1039G+/- mice. The plaque area at the aortic root was increased 1.5- and 2.1-fold in ApoE-/-C1039G+/- mice after 10 and 20 weeks of Western-type diet, respectively. After 10 weeks of Western-type diet, plaques of ApoE-/-C1039G+/- mice showed increased apoptosis of smooth muscle cells, which was associated with a decrease in collagen content, an enlargement of the necrotic core, and an increase in macrophages. After 20 weeks of Western-type diet, the number of buried fibrous caps was increased in atherosclerotic lesions of ApoE-/-C1039G+/- mice, not only at the level of the aortic valves but also in the brachiocephalic artery and in the upper, middle, and lower thoracic aorta. Furthermore, acute plaque rupture was observed.

CONCLUSIONS

These results indicate that fragmentation of the elastic fibers leads to increased vascular stiffness, which promotes features of multifocal plaque instability.

Ascending aortic blood pressure waveform is related to coronary atherosclerosis in hypertensive as well as in normotensive subjects

Ascending aortic blood pressure-derived indices were shown to be related to coronary atherosclerosis. However, no study so far has analyzed the relation between ascending aortic pulsatility and the extent of coronary atherosclerosis in normotensives. Therefore, the aim of the present analysis was to assess the relation between central blood pressure-derived indices and the presence and extent of coronary artery disease in patients with and without hypertension. The study group consisted of 821 patients (590 men and 231 women; mean age: 57.3 +/- 10.0 years) with preserved left ventricular function (ejection fraction>50%) undergoing coronary angiography. Hypertension was diagnosed in 639 (77.8%) patients. Ascending aortic blood pressure during catheterization was measured. After multivariate stepwise adjustment the odds ratio (OR) and confidence interval (CI) of coronary artery disease was: pulsatility per standard deviation (SD) OR 1.36 (95% CI 1.01-1.82) in hypertensives and OR 3.96 (1.95-8.07) in normotensives; pulsatility index per SD OR 1.36 (95% CI 1.01-1.85) in hypertensives and OR 4.41 (2.03-9.56) in normotensives. Stepwise linear regression analysis revealed that pulsatility is related to the mean stenosis in the coronary tree in hypertensives (beta = 0.0862, SE = 0.0448, p<0.05) as well as in normotensives (beta = 0.1704, SE = 0.0718, p<0.05). In conclusion, ascending aortic pulsatility is related to the extent of coronary atherosclerosis irrespectively of the presence of hypertension.

The pulsatile component of blood pressure – Its role in the pathogenesis of atherosclerosis

Pulse pressure (PP) is traditionally believed to increase cardiovascular risk because of an increase in afterload leading to left ventricular hypertrophy. It has also been emphasized that low diastolic blood pressure, being in part responsible for high PP, leads to an impairment of myocardial perfusion with all its adverse consequences. More recently, however, a direct role of pulsatile blood pressure changes in the pathogenesis of atherosclerosis and its complications has become better known. Experimental studies indicate that there is a cause-and-effect type of relationship between the pulsatile component of blood pressure and atherosclerotic process. A significant relationship between the parameters of the pulsatile blood pressure component and the extent of coronary atherosclerosis was also demonstrated. Currently the presence of a bidirectional link between atherosclerosis and PP is commonly postulated, meaning that an increased PP may be both a cause and an effect of atherosclerosis. This may result in a vicious circle wherein the pulsatile blood pressure component induces/enhances the development of atherosclerosis, which in its turn reduces the arterial compliance and enhances pulse wave reflection, thereby leading to an increase in PP. Currently new drug classes are being investigated, which might reduce the pulsatile blood pressure component without changing mean blood pressure level. Their clinical usefulness should become known over the next few years.

Binding of the monomeric form of C-reactive protein to enzymatically-modified low-density lipoprotein: effects of phosphoethanolamine

BACKGROUND

The 5 subunits of native pentameric C-reactive protein (CRP) are dissociated to generate the monomeric form of CRP (mCRP) in some in vitro conditions, both physiological and non-physiological, and also in vivo. Many bioactivities of mCRP generated by urea-treatment of CRP and of mCRP generated by mutating the primary structure of CRP have been reported. The bioactivities of mCRP generated by spontaneous dissociation of CRP are largely unexplored.

METHODS

We purified mCRP generated by spontaneous dissociation of CRP and investigated the binding of mCRP to enzymatically-modified low-density lipoprotein (E-LDL).

RESULTS

mCRP was approximately 60 times more potent than CRP in binding to E-LDL. In the presence of the small-molecule compound phosphoethanolamine (PEt), at 37 degrees C, the binding of mCRP to E-LDL was enhanced <2-fold, while the binding of CRP to E-LDL was enhanced >10-fold. In contrast, PEt inhibited the binding of both CRP and mCRP to pneumococcal C-polysaccharide, another phosphocholine-containing ligand to which CRP and mCRP were found to bind. We have not investigated yet whether PEt alters the structure of CRP at 37 degrees C.

CONCLUSIONS

Combined data suggest that the targeting of CRP with the aim to monomerize CRP in vivo may be an effective approach to capture modified forms of LDL.

Central blood pressure and hypertension: role in cardiovascular risk assessment

Although the differences between central and peripheral BP (blood pressure) have been known for decades, the consequences of decision-making based on peripheral rather than central BP have only recently been recognized. The influence of cyclic stretch (owing to cyclic changes in BP) on the aortic wall in atherosclerosis has been documented at every stage of its development. Apart from mediating atherosclerosis progression and plaque instability, the pulsatile component of BP is the main mechanism leading to plaque rupture and, consequently, to acute coronary syndromes and other vascular complications. The principal goal of the present review is to evaluate the role of central BP measurements, principally systolic and pulse pressure, for cardiovascular risk assessment. Recent findings suggest that the pulsatile component of BP (when represented by central pulse pressure or central pulsatility) is one of the most important factors determining event-free survival. Results of several prospective studies (using both invasive and non-invasive measurements of central BP) indicate not only an independent predictive value of central pulse pressure, but also its advantage over brachial pressure. Recent evidence suggests that some antihypertensive drugs can influence central BP more consistently when compared with peripheral BP. This is especially true for agents acting on the renin–angiotensin system. Nevertheless, large prospective studies aiming at the comparison of the predictive value of peripheral and central BP in the general population, as well as studies comparing the effectiveness of hypertension management based on peripheral compared with central BP measurements, are needed before algorithms based on central BP can be recommended for clinical practice.

Pulsatile but not steady component of blood pressure predicts cardiovascular events in coronary patients

Although the differences between central and peripheral blood pressure (BP) values have been known for decades, the consequences of decision making based on peripheral rather than central BP have only recently been recognized. There are only a few studies assessing the relationship between intraaortic BP and cardiovascular risk. In addition, the relationship between central BP and the risk of cardiovascular events in a large group of coronary patients has not yet been evaluated. Therefore, the aim of the study was to determine the prognostic significance of central BP-derived indices in patients undergoing coronary angiography. Invasive central BPs were taken at baseline, and study end points were ascertained during over a 4.5-year follow-up in 1109 consecutive patients. The primary end point (cardiovascular death or myocardial infarction or stroke or cardiac arrest or heart transplantation or myocardial revascularization) occurred in 246 (22.2%) patients. Central pulsatility was the most powerful predictor of the primary end point (hazard ratio [HR] 1.30, 95% confidence interval [CI] 1.14 to 1.48). Central pulse pressure was also independently related to the primary end point (HR 1.25, 95% CI 1.09 to 1.43). Central mean BP as well as peripheral BP parameters were not independently related to the primary end point risk. Central pulsatility was also related to risk of cardiovascular death or myocardial infarction or stroke. The pulsatile component of BP is the most important factor related to the cardiovascular risk in coronary patients. It is more closely associated with cardiovascular risk than steady component of BP.

C-reactive protein in hypertension: clinical significance and predictive value

Mild elevations in C-reactive protein concentration predict myocardial infarction, stroke, and vascular death in a variety of clinical settings. Despite the lack of specific evidence that C-reactive protein levels are independently associated with cardiovascular risk in patients with hypertension, the prognostic value of C-reactive protein has proven to be complementary to that of blood pressure values. Recent epidemiological evidence has indicated a link between hypertension and increased C-reactive protein levels, and there are some indications that C-reactive protein may predict the future development of hypertension. Vessel wall inflammation is part of the vascular changes observed in animal models of hypertension. C-reactive protein is involved in the complex pathways leading to endothelial dysfunction, increased peripheral vascular resistance, and large artery stiffness in hypertension. In this regard, the role of C-reactive protein as a marker or a causal factor in promoting hypertension and its complications remains, however, to be elucidated. In this review, various aspects of the pathogenesis of inflammation in hypertension are summarized and connected with clinical studies that address the role of C-reactive protein in hypertensive disease.