Aortic hypertrophy and "waterlogging" in the development of coarctation hypertension

To study the mechanisms and roles of vascular structural changes during the development of hypertension, we coarcted or sham-coarcted the abdominal aorta of rats. At intervals of 3 to 56 days later, we obtained standardized segments of thoracic and abdominal aortas for measurement of dry weight, water content, and amino acid content. Carotid arterial pressure was elevated by day 5 in coarcted rats and remained elevated. Femoral and tail arterial pressures remained normal. Cardiac ventricular weight and dry weight of the thoracic aorta, normalized for body weight, rose rapidly over 3-10 days in coarcted rats, remaining constant at 50-60% above levels in sham-coarcted rats thereafter. In contrast, water content of thoracic aorta in coarcted rats peaked at 123% of control values on day 7 (p less than 0.001), falling rapidly thereafter to levels about half of peak. Increments in dry weight and water content of the normotensive abdominal aortic segments were of far lesser magnitude and occurred 1 to 2 weeks later, probably reflecting the effects of initial hypotension of the hindquarters. Percent hydroxyproline of intima-media segments of the thoracic aorta remained normal during the 8-week period, indicating that increases in aortic dry weight did not represent disproportional fibrosis and thus are attributable to muscular hypertrophy. These results provide support for the hypothesis that arterial wall "waterlogging" is primarily an early manifestation of the hypertensive process. The greatest magnitude of waterlogging coincides with the rapid early increase in aortic dry weight, representing hypertrophy, which suggests common mechanisms, such as activation of Na+-H+ antiport.     

Dilation of peripheral vessels in Marfan syndrome: Importance of thoracoabdominal MR angiography

Objectives

Aim of this study was to assess vascular morphology and dimension of the entire aorta and branch vessels in MFS using thoracoabdominal MR angiography (MRA).

Background

Evaluation of vascular involvement in Marfan Syndrome (MFS) is focused to the ascending aorta, which has the major risk of dissection/rupture.

Methods

From March 2006 to January 2011, 64 patients (35 ± 13 years old) with MFS underwent echocardiography and MRA of thoracic and abdominal aorta. Measurements of ascending aorta, aortic arch, descending thoracic and abdominal aorta, and aortic branch vessels were assessed. In patients with aortic dissection only non dissected vessels were considered for measurements.

Results

64 Marfan patients were divided into 2 groups: patients in natural history (group A, 55%) and patients previously submitted to aortic root and/or ascending aorta replacement because of severe aortic dilation or dissection (group B, 45%).Dilation of the descending aorta, mostly of the aortic isthmus, occurred in 18/53 patients (8/35 group A, 10/18 group B). Abdominal aorta resulted in the normal range in group A and in 16/18 patients of group B, while iliac vessels were dilated in 7/35 patients of group A and in 10/23 patients of group B. Four patients of group B presented isolated dilation of subclavian, celiac, mesenteric, or renal arteries.

Conclusions

Vascular dilation beyond the aortic root is not uncommon in MFS. The systematic use of MRA provides a comprehensive evaluation of the entire arterial system.     

Ascending aorta distensibility abnormalities in hypertensive patients and response to nifedipine administration.

PURPOSE: The purpose of the present investigation was to study the distensibility of the ascending aorta in patients with arterial hypertension and normal subjects before and after administration of a calcium antagonist, nifedipine. PATIENTS AND METHODS: The distensibility of the ascending aorta was measured before and after nifedipine administration in 22 male hypertensive patients and 12 age-matched male normotensive subjects. Aortic distensibility was calculated as a function of changes in aortic diameter and pulse pressure, using the formula: 2 x (pulsatile change in aortic diameter)/[(diastolic aortic diameter) x (aortic pulse pressure)]. Aortic diameters were measured by echocardiography and aortic pressures were obtained by catheterization of the ascending aorta. RESULTS: In the basal state, the distensibility of the ascending aorta and aortic strain were lower in hypertensive patients than in normotensive subjects (p < 0.001); the lower aortic distensibility, however, was associated with a greater distending pressure. A good inverse correlation (r = -0.81) was found between mean aortic pressure and aortic distensibility. The aortic distensibility was increased after nifedipine administration in both groups; this increase in aortic distensibility, however, was lower in the patients with hypertension compared with normotensive subjects (p < 0.001). CONCLUSIONS: Aortic distensibility is decreased in patients with arterial hypertension. Nifedipine administration increased the distensibility of the ascending aorta both in patients with arterial hypertension and in normotensive subjects. The increase of aortic distensibility after nifedipine administration was lower in hypertensive patients.     

Comparison of aortic elasticity determined by cardiovascular magnetic resonance imaging in obese versus lean adults

The vascular properties of large vessels in the obese have not been adequately studied. We used cardiovascular magnetic resonance imaging to quantify the cross-sectional area and elastic properties of the ascending thoracic and abdominal aorta in 21 clinically healthy obese young adult men and 25 men who were age-matched lean controls. Obese subjects had greater maximal cross-sectional area of the ascending thoracic aorta (984 +/- 252 vs 786 +/- 109 mm(2), p <0.01) and of the abdominal aorta (415 +/- 71 vs 374 +/- 51 mm(2), p <0.05). When indexed for height the differences persisted, but when indexed for body surface area, a significant difference between groups was found only for the maximal abdominal aortic cross-sectional area. The obese subjects also had decreased abdominal aortic elasticity, characterized by 24% lower compliance (0.0017 +/- 0.0004 vs 0.0021 +/- 0.0005 mm(2)/kPa/mm, p <0.01), 22% higher stiffness index beta (6.0 +/- 1.5 vs 4.9 +/- 0.7, p <0.005), and 41% greater pressure-strain elastic modulus (72 +/- 25 vs 51 +/- 9, p <0.005). At the ascending thoracic aorta, only the pressure-strain elastic modulus was different between obese and lean subjects (85 +/- 42 vs 65 +/- 26 kPa, respectively; p <0.05), corresponding to a 31% difference-but arterial compliance and stiffness index were not significantly different between groups. In clinically healthy young adult obese men, obesity is associated with increased cross-sectional aortic area and decreased aortic elasticity.     

Abnormal ion and water composition of veins and normotensive arteries in coarctation hypertension in rats.

We examined the water, sodium, and potassium composition of the thoracic aorta, abdominal aorta (plus iliac arteries), and veins (vena cava and portal vein) from rats with aortic coarctation. The aortas of 10 rats (group A) were coarcted above the renal arteries to produce hypertension. Control groups consisted of 10 rats sham-coarcted above and 10 rats coarcted below the renal arteries. In group A rats heart weights and carotid artery pressures were elevated over controls (P less than 0.01), whereas there were no significant differences in femoral arterial pressures. In group A rats both the hypertensive thoracic aorta and the normotensive abdominal aorta contained about 20% more water per unit of wet weight, and about 35% and 60% more sodium and potassium, respectively, per unit of dry weight than did the corresponding portions of aorta from control rats (P less than 0.01). In group A rats water (P less than 0.01), sodium (P less than 0.02), and potassium (P less than 0.05) contents of veins also were increased. There were no significant correlations between level of carotid arterial pressure and magnitude of changes in arterial and venous composition, nor were there significant differences between the magnitude of changes in the normotensive and hypertensive portions of the aorta. These results indicate that in rats abnormalities in vascular wall salt and water content are not necessarily a direct effect of the elevated pressure in hypertension.     

Association of left ventricular hypertrophy and aortic dilation in patients with acute thoracic aortic dissection

This study was designed to evaluate the impact of left ventricular mass on aortic diameters in patients who presented with acute thoracic aortic dissection where aortic dilation is common. Retrospective review of transthoracic and transesophageal echocardiograms was conducted for 63 patients treated for acute thoracic aortic dissection and for 16 normal subjects who were comparable for gender prevalence, age, heart rate, and blood pressure. The diameter of the aortic root was measured by transthoracic echocardiography. Diameters of the ascending aorta, and of the aorta at locations of 25, 30, and 35 cm from the dental arch were measured by transesophageal echocardiography. The findings indicated that all aortic diameters were significantly larger in patients with aortic dissection. Patients with aortic dissection also presented with greater left ventricular mass indices (p<0.00001) than normal subjects. Fractional shortening and left atrial diameter measurements obtained in patients with aortic dissection were similar to those obtained in the control group. Overall, the left ventricular mass index exhibited univariate relationships with aortic root diameter (r=0.27, p<0.02) and aortic diameters at 25 cm (r=0.51, p<0.00001), 30 cm (r=0.58, p<0.00001), and 35 cm (r=0.55, p<0.00001) distal to the arch but not with the diameter of the ascending aorta. After adjusting for gender, body mass index, history of hypertension and aortic dissection extent (Stanford types) by separate multivariate models, the authors found that the left ventricular mass index was independently associated with aortic diameters at 25 cm (beta=0.32, p<0.001), 30 cm (beta=0.38, p<0.0001), and 35 cm (beta=0.34, p < 0.0005) distal to the arch. They conclude that left ventricular mass is independently associated with aortic arch and descending aorta diameters in patients with acute thoracic aortic dissection. Left ventricular hypertrophy may be considered a risk factor for aortic enlargement and subsequent dissection.     

The Marfan syndrome: abnormal aortic elastic properties

Aortic distensibility and aortic stiffness index were measured at the ascending aorta (3 cm above the aortic valve) and the mid-portion of the abdominal aorta from the changes in echocardiographic diameters and pulse pressure in 14 patients with the Marfan syndrome and 15 age- and gender-matched normal control subjects. The following formulas were used: 1) Aortic distensibility = 2(Changes in aortic diameter)/(Diastolic aortic diameter) (Pulse pressure); and 2) Aortic stiffness index = ln(Systolic blood pressure)/(Diastolic blood pressure)(Changes in aortic diameter)/Diastolic aortic diameter. Pulse wave velocity was also measured. Compared with normal subjects, patients with the Marfan syndrome had decreased aortic distensibility in the ascending and the abdominal aorta (2.9 +/- 1.3 vs. 5.6 +/- 1.4 cm2 dynes-1, p less than 0.001 and 4.5 +/- 2.1, vs. 7.7 +/- 2.5, cm2 dynes-1, p less than 0.001, respectively) and had an increased aortic stiffness index in the ascending and the abdominal aorta (10.9 +/- 5.6 vs. 5.9 +/- 2.2, p less than 0.005 and 7.1 +/- 3.1 vs. 3.9 +/- 1.2, p less than 0.005, respectively). Aortic diameters in the ascending aorta were larger in these patients than in normal subjects, but those in the abdominal aorta were similar in the two groups. Linear correlations for both aortic distensibility and stiffness index were found between the ascending and the abdominal aorta (r = 0.85 and 0.71, respectively). Pulse wave velocity was more rapid in the patients than in the normal subjects (11.6 +/- 2.5 vs. 9.5 +/- 1.4 m/s, respectively, p less than 0.01). Thus, aortic elastic properties are abnormal in patients with the Marfan syndrome irrespective of the aortic diameter, which suggests an intrinsic abnormality of the aortic arterial wall.     

Obstructive sleep apnea and thoracic aorta dissection

Obstructive sleep apnea syndrome (OSAS) is a process that is associated with the development of arterial hypertension, the main risk factor for aortic dissection and during obstructive episodes of the upper airways with marked increases in transmural pressure of the aorta wall. The aim of this work was to study the association between aortic dissection and OSAS. Nineteen consecutive patients with thoracic aorta dissection and 19 hypertensive patients of similar age, sex, and body mass index were studied by clinical questionnaire and polysomnography. Snoring and nonrefreshing sleep were common in both groups. Thirteen patients (68%) from each group showed an apnea-hypopnea index of more than 5 per hour. However, patients with aortic dissection presented a higher apnea-hypopnea index (28 [30.3] versus 11.1 [10.4], p=0.032). Seven patients with dissection presented an apnea-hypopnea index of more than 30 versus 1 patient in the control group (p=0.042). Patients with thoracic aorta dissection presented a high prevalence of previously undiagnosed and frequently severe OSAS. Further studies, including this diagnosis as a prognostic variable in the follow-up of patients with aortic dissection, are required. Our results suggest that in patients with aortic dissection and symptoms consistent with OSAS, a sleep study should be considered in their clinical management.     

老年人腹主动脉瘤血管平滑肌细胞相关蛋白表达及巨噬细胞浸润的病理学特点

目的 观察血管平滑肌细胞(VSMC)表达变化及巨噬细胞浸润在老年人腹主动脉瘤中的病理学特点. 方法 对15例老年人腹主动脉瘤与6例正常腹主动脉组织行HE染色、VanGieson法染色和免疫组织化学染色.用免疫组织化学染色检测α-平滑肌肌动蛋白(α-SMA)、组织蛋白酶B及CD68蛋白表达. 结果 老年人腹主动脉瘤病变处胶原容积百分比(9.3±1.9)%,较正常主动脉的(5.3±1.8)%增高(P＜0.05).老年人腹主动脉瘤中组织蛋白酶B和CD68的表达增强分别为0.38+0.07和0.51±0.12,α-SMA表达减弱为0.23±0.05,与正常腹主动脉(分别为0.13±0.06和0.01±0.01,0.33±0.05)比较.差异有统计学意义(P＜0.05). 结论 VSMC相关蛋白表达水平改变及巨噬细胞浸润可能参与了老年人腹主动脉瘤血管壁的破坏.     

The middle aortic syndrome: an important feature of Williams' syndrome

The middle aortic syndrome, with diffuse narrowing of the thoracic and abdominal aorta, was present in 10 of 18 patients with Williams' syndrome (55%). There were 3 thoracic coarctations, and 2 abdominal coarctations, with gradients greater than 20 mmHg across the zone of narrowing. Seven patients had mild renal arterial stenosis, and 6 had visceral arterial stenoses. Ten were hypertensive. Measured dimensions of the aortic lumen failed to increase with age in 3 males who had serial angiographic studies. One developed mesenteric arterial stenosis, with mild bilateral renal arterial stenoses, between the ages of 9 and 19 years. Aortic intravascular ultrasound performed in 2 patients confirmed abnormally thick vessel walls with small lumens. Diffusely narrowed and thick-walled stiff arteries, lacking elastin, are a feature of Williams' syndrome. The arteriopathy tends to progress with age, and systemic hypertension is common in teenagers and beyond. The middle aortic syndrome was present in more than half our patients, and does not necessarily reflect a bias because of cardiologic referral. Aortography with measurement of aortic diameters and delineation of the visceral branches is an important requirement for complete evaluation of patients with Williams' syndrome.     

Atherosclerotic enlargement of the human abdominal aorta

Aortic aneurysms usually develop in the atherosclerosis prone infrarenal abdominal aorta. To assess the role of atherosclerosis in aortic enlargement, we studied the relation between plaque formation and aortic size in 30 pressure-fixed male cadaver aortas (age 40-95 years, mean age 67 years). Morphometric analysis of transverse sections of the mid-thoracic and the mid-abdominal aortas included measurement of intimal plaque area, lumen area, plaque and media thicknesses. The area encompassed by the internal elastic lamina area (IEL area) was taken to be an index of aortic size. IEL area increased with age at both the thoracic (r=0.77, P<0.01) and abdominal (r=0.54, P<0.01) aortic levels. The aorta also enlarged with increasing plaque area at the thoracic (r=0.73, P<0.01) and abdominal (r=0.79, P<0.01) levels. Regression analysis of IEL area on age, body weight, height and plaque area revealed that the primary predictor of thoracic aortic size was age, whereas the primary predictor of abdominal aortic size was plaque area. Plaque thickness in the abdominal aorta was greater than in the thoracic aorta (P<0.01). Increased plaque area was associated with a significant decrease in media thickness in the abdominal aorta (r=-0.75, P<0.01) but not in the thoracic aorta. Aortas with relatively enlarged abdominal segments, i.e. those with a thoracic to abdominal ratio of <1.2 (n=13), were compared to those with a normal ratio (> or =1.2, n=17). Relatively large abdominal aortas had twofold greater plaque area (P<0.001), reduced medial thickness (P<0.05), fewer medial elastic lamellae (P<0.01) and greater mural tensile stress (P<0.05) than relatively normal abdominal aortas. We conclude that plaque formation in the infrarenal abdominal aorta in humans is associated with aortic enlargement and decreased media thickness. These changes may be predisposing factors for the preferential development of subsequent aneurysmal dilation in the abdominal aorta.     

Detection of thrombotic vascular lesions by MR tomography

Magnetic resonance tomography (MRT) was used to investigate 54 patients with a variety of vascular lesions; 38 of those had essential hypertension, including malignant arterial hypertension in 9. Sixteen patients had vascular arterial hypertension, with thrombosis-complicated vascular lesions: unilateral renal artery thrombosis was detected in 6, aortic aneurysm with perimural thrombosis, in 5, Leriche's syndrome, in 3, and unilateral iliac artery thrombosis, in 2. Twenty seven normal subjects, investigated by radionuclide angiography, were taken as controls. Hypertensive patients showed aortic convolution, thickened aortic wall and a certain irregularity of signals inside the aortic lumen, an evidence of possible perimural thrombosis as well as turbulent currents. These data coincided with ultrasonic, computerized tomographic and angiographic findings. In patients with unilateral renal arterial thrombosis, an area of prostenotic dilatation or the thrombosed renal artery itself could be clearly seen. In patients with Leriche's syndrome, thrombosed iliac artery was better visualized because of a greater vascular diameter. In patients with aortic aneurysm, aneurysmal bag, with impulses of different intensity inside the lumen and blurred outline, could be clearly seen. It is concluded that MRT can be used for the diagnosis of vascular thrombotic lesions.     

Characteristic change in local pulse wave velocity in different segments of the atherosclerotic aorta in KHC rabbits

BACKGROUND: Pulse wave velocity, conventionally determined between the carotid and femoral arteries, is a useful measure to estimate stiffness of the aorta. We investigated local pulse wave velocity (LPWV) in different segments in the aorta with relatively early-stage atherosclerosis in relation to the extent and severity of atherosclerotic lesions. METHODS: Pressure waves were recorded in eight aortic positions using two catheters with one or two micromanometers to determine LPWV in the ascending aorta, distal end of the aortic arch, proximal, middle, and distal thoracic aortas, and proximal, middle, and distal abdominal aortas in Kurosawa and Kusanagi-hypercholesterolemic (KHC) and normal rabbits aged 10 to 12 months. RESULTS: The LPWV in the KHC rabbit was greatest in the aortic arch, decreased almost to the normal level in the middle and distal thoracic aorta, increased in the proximal abdominal aorta, and showed almost identical change to that in the normal rabbit in the middle and distal abdominal aortic regions. There was significant difference in LPWV in the aortic arch, proximal thoracic, and proximal abdominal aortas between the two rabbit groups. The sclerotic lesion was prominent in the aortic arch, proximal thoracic aorta, and proximal abdominal aortas. The wall was severely thickened with abundant foam cells. The significant increase in LPWV would be mainly related to the increased wall thickness in these aortic regions. CONCLUSIONS: We can conclude that LPWV reflects well the distribution and severity of atherosclerotic lesion and the increased wall thickness in the local aortic region in which pulse waves were traveled.     

Aortic dilatation in patients with large vessel vasculitis: A longitudinal case control study using PET/CT

ObjectiveTo evaluate aortic diameter and predictors of aortic dilatation using ¹⁸FDG-PET/CT in a longitudinally followed cohort of patients with large vessel vasculitis (LVV) compared with controls.MethodsAll consecutive patients with LVV who underwent at least 2 PET/CT scans between January 2008 and May 2015 were included. The first and last PET/CT study was evaluated by a radiologist and a nuclear medicine physician. Diameter and FDG uptake of the aorta was measured at 4 different levels: ascending, descending thoracic, suprarenal and infrarenal abdominal aorta. Twenty-nine age- and sex-matched patients with lymphoma who underwent at least 2 PET/CT scans in the same time interval were selected as controls.Results93 patients with LVV were included in the study. In the time interval between first and last PET/CT study (median time 31 months), the diameter of the ascending, descending thoracic and suprarenal abdominal aorta significantly increased in LVV patients but not in controls. At last PET/CT, patients with LVV compared with controls had higher diameter of ascending [35.41 (5.54) vs 32.97 (4.11) mm, p = 0.029], descending thoracic [28.42 (4.82) vs 25.72 (3.55) mm, p = 0.007] and suprarenal abdominal aorta, mean [25.34 (7.01) vs 22.16 (3.26) mm, p = 0.005] and more frequently had aortic dilatation [19% vs 3%, p = 0.023]. Significant predictors of aortic dilatation were male sex [OR 7.27, p = 0.001] and, only for GCA, hypertension [OR 6.30, p = 0.031]. Finally, GCA patients with aortic FDG uptake grade 3 at first PET/CT, compared to those with aortic FDG uptake ≤2, had significantly higher aortic diameter.ConclusionsPatients with LVV are at increased risk of aortic dilatation compared with age- and sex-matched controls. Significant predictors of aortic dilatation are male sex and, only for GCA, hypertension. GCA patients with aortic FDG uptake grade 3 are at increased risk of aortic dilatation.     

Morpho-Functional Changes of Thoracic Aorta in Atherosclerosis: Multiplane Transesophageal Ultrasound Study

AIM: To elucidate possibilities of multiplane transesophageal ultrasound for assessment of localization and structure of atherosclerotic plaques in the thoracic aorta as well as relationship between changes of elastic-tonic properties, processes of aortic wall remodeling, stage of aortic atheromatosis, and coronary atherosclerosis. MATERIAL: Patients with chronic ischemic heart disease and atherosclerosis of thoracic aorta (n=120), healthy volunteers (n=11, all men, mean age 51-/+8 years). METHODS: Multiplane transesophageal ultrasound with subsequent calculation of parameters of elasticity and stiffness. The classification of C. Pitsavos et al. (1997) was used for grading aortic atheromatosis. RESULTS. Atherosclerotic plaques were found in 109 patients (91%) and 69 patients (58%) had pronounced (stage 3-5) atheromatosis of thoracic aorta. The plaques were most frequently (87%) localized in descending aorta. Calcinated hyperdense plaques, soft plaques with low density, soft plaques with heterogeneous density prevailed in ascending aorta, aortic arch, and descending aorta, respectively. Sensitivity and specificity of thoracic atherosclerosis as predictor of atherosclerotic lesions in coronary vessels were 90 and 65%, respectively. Pronounced diffuse atherosclerosis of thoracic aorta decreased its elastic-tonic properties as evidenced by significant lowering of parameters of elasticity and increase of stiffness index. This process was associated with remodeling of thoracic aorta (progressive passive dilatation, thickening of its wall and lowering of amplitude of systolic excursion). Atheromatosis stage correlated inversely with systolic excursion and parameters of elasticity and directly with stiffness index, intima-media thickness, systolic and diastolic diameters of the aorta. There was also a direct correlation between stage of aortic atheromatosis and age and total score of coronary artery involvement. CONCLUSION: Multiplane transesophageal echocardiography is a highly informative noninvasive method of assessment of morpho-functional changes of thoracic aorta caused by atherosclerosis.     

2-dimensional ultrasonic scanning of the abdominal aorta in arterial hypertension patients

The diagnostic value of two-dimensional ultrasonic scanning of the abdominal portion of the aorta was studied in 72 patients with arterial hypertension. Twenty-eight of these patients who presented no abnormalities by radiopaque and ultrasonic aortography served as control. The test group was comprised of the remaining 44 patients with symptomatic arterial hypertension associated with nonspecific aortoarteritis, atherosclerosis of the aorta and renal arteries and aortal malformation. Four major types of changes of the ultrasonic scanogram in cases of pathology of the abdominal portion of the aorta were identified. Ultrasonic aortography is a sufficiently informative method as compared to radiopaque aortography. The technique is relatively simple and has no contraindications for use. Ultrasonic scanning of the abdominal portion of the aorta should be conducted at the first stage of examination of patients with arterial hypertension.     

Unoperated thoracic aortic aneurysms: survival rates of the patients and determinants of prognosis.

The purpose of this study was to evaluate the long-term prognosis of unoperated thoracic aortic aneurysms, and to detect the risk factors which determine the prognosis of unoperated patients. The subjects were 52 unoperated patients with 58 thoracic aortic aneurysms (22 of the ascending aorta, 36 of the descending aorta or the aortic arch) and 38 with abdominal aortic aneurysms. The survival rates of the patients with ascending aortic aneurysms at 3 years and 5 years and those of the patients with descending aortic aneurysms at 5 years were significantly higher than those of the patients with abdominal aortic aneurysms. The risk factors for rupture of thoracic aortic aneurysms were the large size of aneurysms and non-management by the cardiologist and the risk factors for death unrelated to the aneurysms were patient age, male gender and non-management by the cardiologist.     

Regional circulations in experimental coarctation of the aorta in conscious dogs

Regional blood flows were measured with radioactive microspheres in 35 conscious dogs at various times (between 1 h and 28 days) after creation of a stenosis of the descending thoracic aorta. Mean arterial pressure increased moderately proximal to the stenosis. Distally, arterial pressure decreased below control values immediately after stenosis, then returned gradually toward preconstriction values over 28 days. Plasma renin activity increased sixfold, after aortic constriction of 1 and 6 h, and remained significantly elevated for four days. Blood volume did not change significantly. In some of the vascular beds exposed to the elevated proximal pressure, significant increases in blood flow were noted in the early stages, mainly in the myocardium, the brain, the skeletal muscles and the bones. After 28 days, however, blood flows were significantly reduced in most tissues exposed to the proximal pressure. At this stage, vascular conductance was significantly decreased in the myocardium, the brain, the muscles, the skin and the bones as compared with a sham-operated control group. Several vascular beds perfused by the distal arterial pressure also showed a significant fall in flow after 28 days, notably the small intestine, the skin, the skeletal muscles and the bones. At that stage, vascular conductance was decreased in the small intestine, the muscles, the skin and the bones. Thus, aortic coarctation in dogs was characterized by a late generalized increase in vascular resistance extending to tissues which were never exposed to increased arterial pressure nor to an increased blood flow. These findings suggest that a systemic vasoconstrictor influence overrides local mechanisms in the control of regional circulations in coarctation hypertension.     

Ultrastructure of hypertensive rat aorta. Increased basement membrane-like material

To determine the effect of elevated blood pressure on the ultrastructure of rat aorta, hypertension (average mean pressure 163 +/- 17 mm Hg) was produced by suprarenal aortic coarctation. After 3 weeks, the subendothelium of the hypertensive thoracic aorta showed significantly increased volume measurements for mononuclear leukocytes and basement membrane-like material compared with the sham-operated control group. Focal areas of rarefaction of the subendothelial extracellular material were associated with the nearby presence of mononuclear leukocytes. None of these alterations were found in the normotensive abdominal aorta. The tunica media of hypertensive thoracic aorta also contained significantly increased basement membrane-like material. This new finding in an animal hypertension model is the direct result of the quantitative morphological approach employed in this study. In some rats, the partially constricting aortic ligature compromised the right renal artery leading to ischemic atrophy of the right kidney and hyperreninemia in addition to hypertension. In this group, excluded from the previous analysis and evaluated separately, subendothelial thickening and accumulation of basement membrane-like material in the thoracic aorta were greatly increased compared with the control group and other hypertensive rats. This result could not be attributed to an effect of blood pressure alone and might have been caused in part by humoral factors. Basement membrane accumulation appears to be an important early response of the arterial wall to hypertension or other factors in this rat model.     

Pathophysiology of isolated systolic hypertension in elderly patients: Doppler echocardiographic insights

Systemic hemodynamics were evaluated with aortic pulsed wave Doppler echocardiography in 79 elderly subjects with isolated systolic hypertension participating in the Systolic Hypertension in the Elderly Program (SHEP) and were compared with the values in 39 normal age-matched subjects. Cardiac output was elevated (4.50 +/- 1.13 L/min versus 3.94 +/- 1.12 L/min, p less than 0.05) in patients with isolated systolic hypertension in comparison with values in normal elderly subjects. Systemic vascular resistance did not differ between both groups (2140 +/- 536 dyn.sec/cm-5 versus 2011 +/- 553 dyn.sec/cm-5, p = NS). The mean acceleration of blood during left ventricular ejection was similar in patients with isolated systolic hypertension in comparison with normals (12.6 +/- 5.6 m/sec2 versus 11.5 +/- 3.5 m/sec2, p = NS). Patients with isolated systolic hypertension had significantly decreased arterial compliance, as measured by the stroke volume-to-pulse pressure ratio (0.77 +/- 0.26 cm3/mm Hg versus 1.11 +/- 0.30 cm3/mm Hg, p less than 0.0001). The prevalence of aortic and mitral regurgitation as well as valvular and annular calcification did not differ between analyzed groups. Isolated systolic hypertension in elderly patients appears to be multifactorial, with reduced arterial compliance and increased cardiac output both playing a role.