Distention Of Arteries Research Articles

Association between bone metabolism regulators and arterial stiffness in type 2 diabetes patients

Background and AimOsteopontin (OPN), osteonectin (ON) and osteocalcin (OC) play an important role in the development of vascular calcifications, but it is unclear whether these bone metabolism regulators contribute to the development of arterial stiffness in type 2 diabetes patients. We therefore aim to determine the relationship between plasma concentrations of OPN, ON, OC and arterial stiffness in type 2 diabetes patients. MethodsCross-sectional study of 1003 type 2 diabetes patients included in the Second Manifestations of ARTerial disease (SMART)-cohort. Generalized linear models were used to evaluate the relation between plasma levels of OPN, ON and OC and arterial stiffness as measured by pulse pressure (PP), ankle-brachial index (ABI) (≥0.9), carotid artery distension and an arterial stiffness summary score. Analyses were adjusted for age, sex, kidney function, diabetes duration and diastolic blood pressure.Higher OPN plasma levels were significantly related to a lower ABI (β-0.013; 95%CI −0.024 to −0.002) and a higher arterial stiffness summary score (OR1.24; 95%CI 1.03–1.49). OPN levels were not related to PP (β 0.59; 95%CI −0.63–1.81) or absolute carotid artery distention (β −7.03; 95%CI −20.00–5.93). ON and OC plasma levels were not related to any of the arterial stiffness measures. ConclusionOnly elevated plasma levels of OPN are associated with increased arterial stiffness in patients with type 2 diabetes as measured by the ankle-brachial index and arterial stiffness summary score. These findings indicate that OPN may be involved in the pathophysiology of arterial stiffness and call for further clinical investigation.

Application of Speckle-Tracking in the Evaluation of Carotid Artery Function in Subjects with Hypertension and Diabetes

Speckle-tracking enables direct tracking of carotid arterial wall motion. Timing intervals determined with carotid speckle-tracking and slopes calculated from carotid artery area versus cardiac cycle curves may provide further information on arterial function and stiffness. The proposed arterial stiffness parameters were examined in healthy controls (n= 20), nondiabetic patients with hypertension (n= 20), and patients with type 2 diabetes (n= 21). Bilateral electrocardiographically gated ultrasonograms of the distal common carotid artery were acquired using a 12-MHz vascular probe. Four timing intervals were derived from speckle-tracked carotid arterial strain curves: (1) carotid predistension period, (2) peak carotid arterial strain time, (3) arterial distension period, and (4) arterial diastolic time. In addition, carotid artery area curves were recorded over the cardiac cycle and subdivided into four segments, S1 to S4, relating to arterial distention and contraction periods. Mean far wall predistension period and peak carotid arterial strain time were more delayed in patients with diabetes and hypertension than in controls. Global mean arterial distension period was prolonged and arterial diastolic time was shorter in patients with hypertension and diabetes than in controls. Slopes of segments S2 and S4 were markedly steeper in the combined group of patients with hypertension and diabetes compared with healthy controls (P= .03 and P= .02, respectively). Speckle-tracking-based measures of arterial stiffness may provide potential additive value in assessing vascular function in patients at risk for cardiovascular disease.

Local Uteroplacental Influences are Responsible for the Induction of Uterine Artery Myogenic Tone during Rat Pregnancy

Uterine artery constrictor responses to elevation of intraluminal pressure (myogenic tone) are considerably enhanced in late pregnant rats, although the underlying causes remain unknown. A single uterine horn ligation model was used to differentiate local from systemic influences, and to test the hypothesis that factors associated with the site of placentation, rather than systemic hormonal changes, are primarily involved in the induction of this adaptive process. Radial uterine arteries were dissected from the gravid and nongravid uterine horns of late pregnant rats, cannulated, and pressurized. Changes in arterial diameter and smooth muscle [Ca(2+)](i) in response to the elevation of intraluminal pressure were studied using intact and endothelium-denuded arteries loaded with the ratiometric Ca(2+)-sensitive dye fura-2. Elevations of pressure from 10 to 60 and 100 mm Hg resulted in passive arterial distention of arteries from nongravid horns with a minor change in [Ca(2+)](i). In contrast, arteries from gravid horns developed myogenic tone associated with a significant elevation in [Ca(2+)](i). Synchronous oscillations in [Ca(2+)](i) and lumen diameter were frequently observed in vessels from gravid horns. Endothelial denudation augmented tone in the gravid horn but did not uncover myogenic tone in vessels from the nongravid horn. In summary, pregnancy-associated uterine artery myogenic behavior is due to an upregulation of calcium-handling mechanisms, occurs independently of the endothelium, and is induced by local uteroplacental influences.

Experimental pulmonary embolism: Effects of the thrombus and attenuation of pulmonary artery injury by low-molecular-weight heparin

Pulmonary embolism (PE) is a life-threatening condition that is associated with the long-term sequelae of chronic pulmonary hypertension. Prior experimental work has suggested that post-PE inflammation is accompanied by pulmonary artery intimal hyperplasia. This study evaluated the effect of the thrombus and tested the hypothesis that thrombolytic, antiplatelet, and anticoagulant agents would decrease pulmonary injury. Male Sprague-Dawley rats (n = 267) underwent laparotomy and temporary clip occlusion of the infrarenal inferior vena cava for the formation of endogenous thrombus or placement of an inert silicone "thrombus." Two days later, repeat laparotomy was performed, the clip removed, and the thrombus or silicone plug was embolized to the lungs. The endogenous thrombus group received normal saline, low-molecular-weight heparin (LMWH), tissue plasminogen activator (tPA), or a gIIB/IIIA antagonist (abciximab). Lung tissue was harvested at various times over 21 days and assayed for total collagen, monocyte chemoattractant protein-1 (MCP-1), interleukin-13 (IL-13), and transforming growth factor-beta (TGF-beta). Fixed sections were stained with trichrome for intimal hyperplasia determination and ED-1 monocytes and alpha-actin-positive staining. The overall survival for rats undergoing PE was 90%, was not affected by treatment, and 84% of all PE localized to the right pulmonary artery. The PE significantly reduced Pa(O2) in all groups. Compared with controls, the silicone emboli group had an increased level of IL-13 on day 1, an increased level of MCP-1 on day 4, and an increase in the levels of all inflammatory mediators on day 14 (P < .05). Accompanying these differences were greater pulmonary artery intimal hyperplasia at days 4 and 21 in the silicone group compared with controls (P < .05). LMWH treatment in the thrombus of PE rats significantly decreased IL-13 levels at all time points, whereas treatment with abciximab or tPA significantly increased IL-13 levels compared with controls. TGF-beta levels were significantly increased by LMWH at day 4 and 14, and abciximab was associated with lower TGF-beta at day 14. Only LMWH was associated with less pulmonary artery intimal hyperplasia at day 14 compared with controls and the other treatment groups. Persistent pulmonary artery distention by an inert material is sufficient to invoke significant inflammation and intimal hyperplasia independent of the thrombus itself. Compared with nontreated PE, LMWH is the only therapy associated with a significant reduction in late intimal hyperplasia and, with the exception of TGF-beta, lower profibrotic growth-factor production.

Understanding the Doppler RI: impact of renal arterial distensibility on the RI in a hydronephrotic ex vivo rabbit kidney model.

The aim of this study was to evaluate the influence of elevated ureteral pressure on renal arterial distention, and thereby on the Doppler resistive index. Seven isolated rabbit kidneys were subjected to a pulsatile perfusion while the renal pelvis was pressurized via the ureter. Renal vascular pressure, flow, resistance (pressure/flow) and conductance (flow/pressure) were compared to simultaneous resistive index measurements using linear regression analysis. Changes in the Conductance Index (systolic conductance - diastolic conductance/systolic conductance) were likewise compared to the resistive index. Elevations in ureteral pressure were significantly correlated with (1) increased resistive index values, (2) increased mean renal vascular resistance, (3) decreased mean conductance, and (4) increased conductance index values (for all correlations P < 0.05). The increases in the resistive index correlated significantly with increases in the conductance index. This study shows that elevated ureteral pressure, likely acting via interstitial pressure, diminishes the conductance of the renal vascular bed. Because this effect is more dramatic at diastole, the cyclic patterns of flow are altered, resulting in elevated resistive index values. The results indicate the importance of the interaction between vascular distensibility and pulsatile flow, rather than overall mean renal vascular resistance, in determining resistive index values.

An improved technique for the internal mammary artery coronary bypass graft procedure.

An improved technique for internal mammary artery graft preparation is described. Following cautery dissection of the internal mammary artery (IMA) pedicle, the pedicle investing fascia is incised to the adventitial level along a single plane. This incision allows the tissue around the internal mammary artery to fall away and severs the muscular constrictions that often surround the internal mammary artery. Balloon calibration is performed to identify remaining constrictions and to relieve internal mammary artery spasm. A shear force limiting gauge insures that the exerted balloon force remains below the level demonstrated to cause intimal damage during electron microscopic studies. This technique allows full internal mammary artery distention without the devascularizing effects of full skeletonization. Distention of the distal internal mammary artery provides an enlarged hood to facilitate suture placement. Elongation of the internal mammary artery during balloon calibration aids in the performance of sequential grafts. This technique has been applied to 793 patients over the past five years. Postcalibration flow rates increased 3- to 18-fold over precalibration flow rates. Two early occlusions occurred during this series, one due to endothelial strippage prior to the development and use of the shear force limiting gauge. Follow-up showed 93.3% of patients to be asymptomatic. This combination of fascial incision and balloon calibration appears to offer safe technical and functional improvements to the performance of the internal mammary artery graft.

Effect of pulmonary artery distention on systemic vascular resistance in newborn lambs

Balloon distention of the left pulmonary artery (PA) was produced in 14 lambs (aged 1 to 3 days) to assess whether an increase in systemic vascular resistance results from such distention. The lambs were anesthetized with chloralose and instrumented to enable measurement of systemic blood flow, PA pressure, aortic pressure, heart rate and right atrial pressure. PA distention resulted in an increase in systemic vascular resistance and aortic pressure (p <0.05). This result was probably due to a systemic vasoconstrictor response, since systemic blood flow and right atrial pressure did not change significantly. Limited trials using autonomic blocking agents suggested that the response is either a reflex under autonomic control or a response to humoral release of α-adrenergic substances. In conclusion, some interdependence appears to exist between the systemic and pulmonary vascular beds. It is postulated that such changes may be important in fetal life when they may affect redistribution of cardiac output during adaptation to hypoxemia.

Is there a difference between classic and common migraine? What is migraine, after all?

In the Classification of Headache developed by the select committee of the National Institutes of Health in 1962, the following definitions are given 1 : VASCULAR HEADACHES OF THE MIGRAINE TYPE These consist of recurrent attacks of headache, widely varied in intensity, frequency, and duration. The attacks are commonly unilateral in onset, are usually associated with anorexia and sometimes nausea and vomiting, in some are preceded by or associated with conspicuous sensory, motor, and mood disturbances; they are often familial. Evidence supports the view that cranial arterial distention and dilatation are importantly implicated in the painful phase, but cause no permanent changes in the involved vessel. The following are particular varieties of headache, each sharing some but not necessarily all the previously mentioned features: Classic migraine, is a vascular headache with sharply defined, transient visual or other sensory and/or motor prodromes. Common migraine, is a vascular headache without striking prodromes and

Main pulmonary artery distention: A potential mechanism for acute pulmonary hypertension in the human newborn infant

Balloon-induced distention of the main pulmonary artery causes acute pulmonary hypertension and reflex pulmonary vasoconstriction in animals. Pulmonary artery pressure responses caused by MPA balloon inflation were measured in ten human newborn infants with cardiac failure (n = 5) or persistent fetal circulation (n = 5). During balloon inflation distal mean PAP increased significantly while cardiac rate remained unchanged. MPA distention caused greater increases of PAP in those infants with lower resting PAP. The greatest balloon-induced increases of PAP were observed in infants recovering from PFC. The existence of a pulmonary artery reflex and its possible role in the regulation of the human fetal and neonatal pulmonary circulation is discussed.

Nonlinear analysis of aortic flow in living dogs.

A nonlinear theory which considered the convective accelerations of blood and the nonlinear elastic behavior and taper angle of the vascular wall was used to study the nature of blood flow in the descending thoracic aorta of living dogs under a wide range of pressures and flows. Velocity profiles, wall friction, and discharge waves were predicted from locally measured input data about the pressure-gradient wave and arterial distention. Precision pressure-gradient waves free of static errors were obtained through forward and backward pressure-gradient measurements, and the arterial pressure-radius relation was obtained through cinematography using a telephoto lens. The results indicated that a major part of the mean pressure gradient was balanced by convective accelerations; the theory, which took this factor into account, predicted the correct velocity distributions and flow waves. The results also showed that for high flow rates the magnitude of the peak wall-shear stress became comparable to the yield stress of the endothelial surface and that radial flows of significant magnitude existed with respect to the arterial wall.

Pulmonary Vasoconstriction Due to Nonocclusive Distention of Large Pulmonary Arteries in the Dog

The pulmonary vascular changes caused by distention of the pulmonary artery with the lumen fixed were compared to those produced by occlusive arterial distention. In 13 urethane-anesthetized dogs, nonocclusive distention was produced by distention of a corrugated rubber cuff around a hollow metal cylinder affixed to the end of a cardiac catheter. In 10 other dogs, occlusive distention was produced by inflation of a standard balloon catheter. Pressures were measured in large and small pulmonary veins and in the left and right atria with transseptal techniques, and in the pulmonary and femoral arteries. Simultaneously, pulmonary blood volume and flow were measured with dyedilution techniques. Pulmonary arteriovenous shunting was studied with the hydrogen-electrode technique. Nonocclusive distention of a pulmonary artery greatly increased pulmonary arterial and venous pressure and decreased pulmonary blood volume without changing left atrial pressure or cardiac output. Pulmonary vascular resistances increased, and pulmonary arteriovenous shunting was detected. Occlusive distention of one pulmonary artery caused smaller increases in pressure in the pulmonary artery and vein of the unobstructed lung. Vascular resistances in the unobstructed lung decreased, while blood volume and flow in that lung doubled. Pulmonary arterial distention leads to active constriction of the pulmonary arteries and veins, but these responses may be obscured by the passive responses to increasing blood flow and volume.

Compressibility of the coronary artery by pulmonary artery distention ∗

Compressibility of the coronary artery by pulmonary artery distention ∗