Measuring hypertensive cardiovascular risk: the vascular overload concept

Associations Between Estimates of Arterial Stiffness and Cognitive Functioning in Adults With HIV

BACKGROUND

Vascular aging, a precursor of arterial stiffness, is associated with neurocognitive impairment (NCI) and cardiovascular disease. Although HIV is associated with rapid vascular aging, it is unknown whether arterial stiffness mediates changes in cognitive function. We explored whether estimated markers of vascular aging were associated with NCI indices in HIV-positive individuals.

METHODS

This study was a secondary analysis of an observational study. Neurocognitive functioning was assessed using a battery of 7 domains (verbal fluency, executive functioning, speed of information processing, attention/working memory, memory [learning and delayed recall], and motor skills). Vascular aging was assessed using estimated markers of arterial stiffness (ie, estimated pulse wave velocity, pulse pressure, and vascular overload index). A multivariable regression adjusted for demographics, cardiovascular disease risk factors, and HIV clinical variables was used to examine the association between vascular aging and NCI outcomes.

RESULTS

Among 165 people with HIV, the mean age was 51.5 ± 6.9 years (62% men and 83% African American/Black or Other). In fully adjusted models, an increase in estimated pulse wave velocity and pulse pressure was associated with lower T scores in learning (-2.95 [-5.13, -0.77]) and working memory (-2.37 [-4.36, -0.37]), respectively. An increase in vascular overload index was associated with lower T scores in working memory (-2.33 [-4.37, -0.29]) and learning (-1.85 [-3.49, -0.21]).

CONCLUSIONS

Estimated markers of arterial stiffness were weakly associated with neurocognitive functioning, suggesting that vascular aging may have a role in cognitive decline among people with HIV.

Use of the Vascular Overload Index to Predict Cardiovascular Disease in a Rural Population of China

Objective

To explore the relationship between vascular overload index (VOI) and cardiovascular disease (CVD) in rural population and find effective ways to prevent cardiovascular disease in rural low-income populations.

Methods

The data for this study was obtained from a large cohort study called the Northeast China Rural Cardiovascular Health Study (NCRCHS) conducted in 2013 and followed up during 2015-2018. 10,174 subjects completed at least one follow-up visit. Cox regression equation was used to explore whether VOI and cardiovascular disease were independently related. The Kaplan-Meier curves were used to calculate the cumulative incidence of any adverse outcome, and the log-rank test and restrict mean survival analysis were used to compare group differences. Reclassification and discrimination statistics were used to determine whether VOI could strengthen the ability of the model to predict CVD events.

Results

The prevalence of CVD in the VOI quartiles was 1.92%, 3.96%, 5.42%, and 11.34% for Q1-Q4, respectively (P for trend <0.001). After adjusting for multiple confounders, there was a 2.466-fold increased risk of CVD when comparing the highest and lowest groups. Besides, this study found that for every standard deviation increase, the results still exist. The risk of cardiovascular disease increased by 1.358-fold in this model. The restrict mean survival analysis results show that with the increase of VOI, the restrict mean survival time (RMST) within 5 years gradually became shorter. Reclassification and discrimination statistics indicated that VOI significantly enhanced the ability to estimate CVD events within 4 years.

Conclusion

Analyses showed that VOI was significantly associated with CVD. VOI is a simple and accurate prognostic marker of CVD risk, which has the potential ability to improve the risk stratification of CVD.

Central Haemodynamics Are Associated With Pulmonary Function in Postmenopausal Women

PURPOSE

Increased arterial stiffness predicts cardiovascular disease, which is associated with deteriorated pulmonary function and worsened chronic obstructive pulmonary disease. The present study examined whether arterial function was associated with pulmonary function in postmenopausal women.

METHODS

This study evaluated 41 postmenopausal women (age range: 59-85 years). Arterial function was measured as central systolic blood pressure (cSBP), central pulse pressure (cPP), brachial systolic BP (bSBP), brachial diastolic BP (bDBP), brachial PP (bPP), brachial mean arterial pressure (bMAP) and the augmentation index (AIx). AIx was adjusted for a heart rate of 75 beats per minute (bpm) (AIx@75) and served as the index of arterial stiffness determined by the reflected wave at the central artery. Pulmonary function was measured as forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁) and the FEV₁/FVC ratio.

RESULTS

Univariate regression analysis demonstrated that cPP, bDBP and bPP were correlated with FVC and FEV₁ (p<0.05, respectively), while AI@75 was correlated with FVC, FEV₁ and FEV₁/FVC ratio (p<0.01, respectively). A stepwise multivariate regression analysis revealed that bDBP was independently associated with FVC (p=0.032), while AI@75 was independently associated with FVC, FEV₁ and FEV₁/FVC ratio (p=0.001, p=0.003 and p=0.017, respectively). The FVC, FEV₁ and FEV₁/FVC ratio were lower in participants with a high AIx versus with a low AIx (p=0.0001, p=0.001 and p=0.044, respectively).

CONCLUSION

These results suggest that increased AIx is associated with lower pulmonary function in postmenopausal women.

Association Between Vascular Overload Index and New-Onset Ischemic Stroke in Elderly Population with Hypertension

Background

Vascular overload index (VOI) is a marker of arterial stiffness and arteriolar resistance, which predicts the increasing risks of cardiovascular and cerebrovascular disease. This study aimed to evaluate the association between VOI and new-onset ischemic stroke in an elderly population with hypertension.

Methods

This retrospective cohort study included 3315 hypertensive participants aged 60 years or more. Ischemic stroke was diagnosed according to cranial computed tomography, magnetic resonance imaging of the brain or cerebrovascular angiography. The calculation of VOI was based on systolic and diastolic blood pressure. VOI was divided by quartiles (<7.88 mmHg, 7.88–16.10 mmHg, 16.10–27.14 mmHg, ≥27.14 mmHg) and evaluated the association with new-onset ischemic stroke by multivariable Cox regression models.

Results

A total of 3315 participants (55.5% female) aged 71.4±7.20 years were included in the analysis. The median follow-up period was 5.5 years, and 206 participants reached the endpoint, new-onset ischemic stroke. With per standard deviation increment in VOI, the risks of new-onset ischemic stroke increased in non-adjusted model (Hazard ratio [HR], 1.11; 95% confidence interval [CI]: 1.03–1.22; p = 0.001), adjusted model (HR, 1.11; 95% CI: 1.04–1.22; p = 0.003) and fully-adjusted model (HR, 1.15; 95% CI: 1.08–1.26; p<0.001), respectively. In multivariate fully adjusted model, the risks of ischemic stroke increased in higher quartiles in comparison to the first quartiles (p for trend <0.001).

Conclusion

In an elderly hypertensive population, VOI is significantly associated with the incidence of new-onset ischemic stroke. Elevated VOI is the cardiovascular risk factor and increases the probability of new-onset ischemic stroke.

Aortic function quantified: the heart's essential cushion

Arterial compliance is mainly determined by the elasticity of proximal large-conduit arteries of which the aorta is the largest contributor. Compliance forms an important part of the cardiac load and plays a role in organ (especially coronary) perfusion. To follow local changes in aortic compliance, as in aging, noninvasive determination of compliance distribution would be of great value. Our goal is to determine regional aortic compliance noninvasively in the human. In seven healthy individuals at six locations, aortic blood flow and systolic/diastolic area (ΔA) was measured with MRI. Simultaneously brachial pulse pressure (ΔP) was measured with standard cuff. With a transfer function we derived ΔP at the same aortic locations as the MRI measurements. Regional aortic compliance was calculated with two approaches, the pulse pressure method, and local area compliance (ΔA/ΔP) times segment length, called area compliance method. For comparison, pulse wave velocity (PWV) from local flows at two locations was determined, and compliance was derived from PWV. Both approaches show that compliance is largest in the proximal aorta and decreases toward the distal aorta. Similar results were found with PWV-derived compliance. Of total arterial compliance, ascending to distal arch (segments 1-3) contributes 40% (of which 15% is in head and arms), descending aorta (segments 4 and 5) 25%, and "hip, pelvic and leg arteries" 20%. Pulse pressure method includes compliance of side branches and is therefore larger than the area compliance method. Regional aortic compliance can be obtained noninvasively. Therefore, this technique allows following changes in local compliance with age and cardiovascular diseases.

A physiologically relevant, simple outflow boundary model for truncated vasculature

A realistic outflow boundary condition model for pulsatile flow in a compliant vessel is studied by taking into account physiological effects: compliance, resistance, and wave reflection of the downstream vasculature. The new model extends the computational domain with an elastic tube terminated in a rigid contraction. The contraction ratio, the length, and elasticity of the terminal tube can be adjusted to represent effects of the truncated vasculature. Using the wave intensity analysis method, we apply the model to the test cases of a straight vessel and the aorta and find good agreement with the physiological characteristics of blood flow and pressure. The model is suitable for cardiac transient (non-periodic) events and easily employed using so-called black box software.

High pulse pressure as a marker of preclinical cardiovascular disease

Increasing attention has been focused on the pathophysiology and prognostic relevance of increased pulse pressure. High systolic pressure increases vascular load whereas low diastolic pressure reduces coronary perfusion pressure, both of which provide pathophysiological explanations for the prognostic value of pulse pressure. In a recent study we have demonstrated that in the presence of either normal or high peripheral resistance, brachial pulse pressure is associated with an increase in left ventricular mass and in arterial stiffness. As indicated in our study, a brachial pulse pressure over 63 mmHg represents a sign of established cardiovascular damage in the setting of arterial hypertension. Accordingly, we suggest elevated brachial pulse pressure should be considered a marker of established preclinical cardiovascular disease rather than a risk factor for the development of arterial disease.

Mean aortic pressure is the geometric mean of systolic and diastolic aortic pressure in resting humans

The aim of our study was twofold: 1) to establish a mathematical link between mean aortic pressure (MAP) and systolic (SAP) and diastolic aortic pressures (DAP) by testing the hypothesis that either the geometric mean or the harmonic mean of SAP and DAP were reliable MAP estimates; and 2) to critically evaluate three empirical formulas recently proposed to estimate MAP. High-fidelity pressures were recorded at rest at the aortic root level in controls (n = 31) and in subjects with various forms of cardiovascular diseases (n = 108). The time-averaged MAP and the pulse pressure (PP = SAP - DAP) were calculated. The MAP ranged from 66 to 160 mmHg [mean = 107.9 mmHg (SD 18.2)]. The geometric mean, i.e., the square root of the product of SAP and DAP, furnished a reliable estimate of MAP [mean bias = 0.3 mmHg (SD 2.7)]. The harmonic mean was inaccurate. The following MAP formulas were also tested: DAP + 0.412 PP (Meaney E, Alva F, Meaney A, Alva J, and Webel R. Heart 84: 64, 2000), DAP + 0.33 PP + 5 mmHg [Chemla D, Hébert JL, Aptecar E, Mazoit JX, Zamani K, Frank R, Fontaine G, Nitenberg A, and Lecarpentier Y. Clin Sci (Lond) 103: 7-13, 2002], and DAP + [0.33 + (heart rate x 0.0012)] PP (Razminia M, Trivedi A, Molnar J, Elbzour M, Guerrero M, Salem Y, Ahmed A, Khosla S, Lubell DL. Catheter Cardiovasc Interv 63: 419-425, 2004). They all provided accurate and precise estimates of MAP [mean bias = -0.2 (SD 2.9), -0.3 (SD 2.7), and 0.1 mmHg (SD 2.9), respectively]. The implications of the geometric mean pressure strictly pertained to the central (not peripheral) level. It was demonstrated that the fractional systolic (SAP/MAP) and diastolic (DAP/MAP) pressures were reciprocal estimates of aortic pulsatility and that the SAP times DAP product matched the total peripheral resistance times cardiac power product. In conclusion, although the previously described thumb-rules applied, the "geometric MAP" appears more valuable as it established a simple mathematical link between the steady and pulsatile component of aortic pressure.

Is High Pulse Pressure a Marker of Preclinical Cardiovascular Disease?

This study tests the hypothesis that high brachial pulse pressure might constitute preclinical cardiovascular disease, rather than a risk factor. We studied 1250 subjects (472 nonobese normotensive [<135/80 mm Hg] and 778 untreated hypertensive). Central pulse pressure was estimated from brachial pulse pressure and age and divided by stroke volume (PP/SV). Brachial pulse pressure was considered high when >63 mm Hg, and peripheral resistance high when >90th percentile of normal distribution. Among hypertensive subjects, 34% had high resistance; among them, 33% had high brachial pulse pressure, as opposed to 147 of 516 patients (28.5%) with normal resistance ( P =not significant). After adjusting for age, sex, race, body mass index, heart rate, and center, left ventricular (LV) internal dimension and mass were lower with high resistance, and higher when brachial pulse pressure was high. PP/SV was 36% higher with high resistance than with normal resistance, and higher when brachial pulse pressure was high (all P <0.0001). Factorial analysis demonstrated that associations of high brachial pulse pressure with both higher PP/SV and LV mass were independent of other pressure components. Thus, because of these associations, our hypothesis is that in hypertension, pulse pressure may be considered as a marker of preclinical cardiovascular disease, similar to LV mass and PP/SV, rather than a cardiovascular risk factor.

Wide pulse pressure is an independent predictor of cardiovascular mortality in Puerto Rican men

BACKGROUND AND AIM

Emerging evidence suggests that pulse pressure is an independent predictor of risk for cardiovascular mortality. New studies in diverse populations are needed to further establish the applicability of this finding. Thus, the purpose of this study is to examine the relationship between pulse pressure and cardiovascular mortality in a cohort of Puerto Rican men after 12 years of follow-up.

METHODS AND RESULTS

The Puerto Rico Heart Health Program is a study of coronary disease risk factors in men aged 35-79 years at baseline who had an initial examination during the years 1962-1965. It was attended by 9824 subjects representing 80% of the total age-specific male residents in 4 rural and 3 urban areas of Puerto Rico. Cardiovascular risk factors including systolic and diastolic blood pressures were monitored prospectively. This study includes 9106 men free of overt CHD at baseline who were stratified by quartiles of pulse pressure in mmHg: quartile 1, <or=38, quartile 2, 39-46; quartile 3, 47-56; and quartile 4, >or=57. The odds ratio of cardiovascular mortality was calculated using logistic regression analysis. After adjusting for age, education, smoking status, hypercholesterolemic status, physical activity, diabetic status and mean arterial pressure, we found that those in the highest quartile of pulse pressure (pulse pressure>=57) had significantly higher cardiovascular mortality than those in the lowest quartile (reference group) (OR=1.38 95% CI=1.01-1.88).

CONCLUSION

Our findings showed that a wide pulse pressure is independently associated with cardiovascular mortality in this group of Puerto Rican men.

The effect of hypertension as a predictor of risk for congestive heart failure patients over a 10-year period in a newly developed country

AIMS

Cardiovascular disease is the leading cause of mortality and morbidity in the western world and has reached epidemic proportions. The incidence of congestive heart failure (CHD) and hypertension is also rising rapidly in many of the affluent Arab nations and cardiovascular diseases continue to be a leading cause of morbidity and mortality among adult Qataris and Asians residing in Qatar.

OBJECTIVE

The objective of this study is to assess the effect of hypertension among patients admitted to hospital in Qatar with CHD and to identify risk factors that contribute to the development of CHD in hypertensive subjects.

DESIGN

This is a retrospective cohort study.

SETTING

Hamad General Hospital, Hamad Medical Corporation.

SUBJECTS

All patients who were hospitalized with CHD with or without hypertension in the Hamad General Hospital, State of Qatar, from 1991 to 2001.

METHODS

The diagnostic classification of definite CHD was made in accordance with criteria based on the International Classification of Disease, ninth revision (ICD-9].

RESULT

A total of 20,856 patients were treated during the 10-year period; 8446 were Qataris. Among them, 60% were males and 40% females. Among the total patients (3713) hospitalized with CHD, 1744 (46.9%) had hypertension. Furthermore, the incidence of hypertension was slightly higher in males than in females (56.4 vs 43.6%). A statistically significant difference was found between hypertensive and non-hypertensive cases with diabetes mellitus and angina. Hypertensive subjects were more likely to have diabetes (p < 0.001) and angina (p < 0.030). The mortality rate of CHD patients with hypertension was higher among Qataris than among non-Qataris (p < 0.038).

CONCLUSION

Hypertension was the most common risk factor for CHD; it contributed a large proportion of heart failure cases in this population-based sample. Preventive strategies directed toward earlier detection of elevated blood pressure and its control are likely to offer the greatest promise for reducing the incidence of CHD and its associated mortality.

Associations of blood pressure with carotid intima-media thickness in elderly Finns with diabetes mellitus or impaired glucose tolerance

The aim of the present study was to evaluate the associations of ultrasonographic manifestations of carotid atherosclerosis with systolic (SBP) and diastolic blood pressure (DBP) and pulse pressure (PP) in 65-year-old Finns drawn from a population-based cohort. Carotid ultrasonographic measurements were performed on 54 diabetic subjects, 97 subjects with impaired glucose tolerance (IGT) and 57 normoglycaemic subjects (NGT). The subjects were classified into four quartiles of SBP, DBP and PP. SBP, DBP, PP and the use of antihypertensive drugs increased along with the deterioration of glucose status. The maximal intima-media thickness (IMT) of the common carotid artery (CCA) from the lowest to the highest quartiles of SBP was 0.98+/-0.34, 1.00+/-0.35, 1.03+/-0.29, 1.18+/- 0.52 mm (P=0.038), respectively. SBP was higher (161+/-22 mmHg) in the subjects with severe intima-media thickening (maximal IMT CCA > or =1.2 mm) than in those with maximal IMT CCA of <1.2 mm (153+/- 20 mmHg) (P=0.030). DBP and PP tended to be higher in the former than the latter group (DBP: 89+/-9 mmHg vs 86+/-9 mmHg, P=0.055 and PP: 72+/-18 mmHg vs 67+/-17 mmHg, P=0.159). The prevalence of severe intima-media thickening was 39% in the subjects in the highest SBP quartile (> or =170 mmHg) and 20% in the subjects with lower SBP (P=0.008). In multiple regression analysis, the adjusted OR for severe intima-media thickening was 2.9 (95% CI 1.1-7.9) in the subjects in the highest SBP quartile compared to the subjects with lower SBP. In the present study, high SBP was associated with severe carotid intima-media thickening. We suggest that the results can be generalized to apply to elderly Finnish subjects with DM and IGT, but not to normoglycaemic subjects, on the basis of this study.

Resting and reactive blood pressure. Predictors of ambulatory blood pressure in older adults with hypertension

The study examined whether reactive change scores from a short blood pressure (BP) reactivity protocol, resting BP, or resting pulse pressure (PP) would be predictors of 24-hour ambulatory BP and BP load in cardiac patients. The study used a single-group design, with both an experimental clinical component and an observational field component. Both components used repeated measurement methods. The study population consisted of 45 adult patients with a mean age of 64.6 +/- 8.5 years who were diagnosed with cardiac disease in a cardiac rehabilitation program and who were taking anti-hypertensive medication. Blood pressure reactivity was operationalized with a speech protocol. During the speech protocol, BP was measured with an automatic device (Dinamap) while patients talked about their health and about their usual day. Twenty-four-hour ambulatory BP measurement followed the speech protocol. Resting systolic BP and resting PP were significant predictors of 24-hour ambulatory systolic BP, and resting systolic BP was a significant predictor of systolic BP load. No predictors were significant of 24-hour diastolic BP or diastolic BP load. Initial resting BP and PP may be used in clinical settings to assess hypertension management. Future studies are necessary to confirm the ability of resting BP to predict ambulatory BP and BP load in older adults who are medicated and hypertensive.

Spurious systolic hypertension in youth

Six young men diagnosed with systolic hypertension had normal carotid pressure wave contours, normal synthesized aortic pressure wave contours and normal diastolic and mean pressures in upper limb arteries. Elevated brachial systolic pressure was caused by a high narrow systolic peak of the pressure wave. This was attributed to amplification of the pressure wave between the ascending aorta and upper limb (radial and brachial) arteries that is associated with attainment of full body length and very distensible arteries. These young men were not truly hypertensive. Exaggeration of the upper limb systolic peak represented an extreme of the normal pressure wave pattern in youth, where amplification is greater than in childhood or in older subjects. This phenomenon accounts for the rapid increase in systolic pressure between the ages of 5 and 20 years, and the relative plateau in systolic pressure between the ages of 20 and 45 years that is seen in population studies.

Is there a preferred antihypertensive therapy for isolated systolic hypertension and reduced arterial compliance?

Isolated systolic hypertension (ISH) is the most common type of hypertension and the most difficult type to control with antihypertensive therapy. ISH, by definition, is wide pulse pressure hypertension resulting largely from excessive large artery stiffness and representing an independent risk factor for cardiovascular disease in the older aged population. Two major intervention studies of ISH have shown significant benefit in reducing systolic blood pressure with active drug therapy, including thiazide diuretics and calcium receptor antagonists. The optimal treatment strategy is to maximize reduction in systolic blood pressure and to minimize reduction in diastolic blood pressure, thereby reducing pulse pressure. All classes of antihypertensive drugs reduce pulse pressure by means of lowering peripheral resistance, but certain drugs like nitrates, angiotensin converting enzyme inhibitors, and other drugs affecting the renin-angiotensin system have multiple actions that improve large artery stiffness and early wave reflection and are especially useful in treating ISH in the elderly.

Excess mortality associated with increased pulse pressure among middle-aged men and women is explained by high systolic blood pressure

OBJECTIVE

To assess the risk of death from coronary heart disease, stroke, all cardiovascular diseases and all-cause mortality associated with pulse pressure among the middle-aged population.

METHODS AND DESIGN

A prospective 15-year follow-up cohort study was conducted of two independent cross-sectional random samples of the population who participated in baseline surveys in 1972 or 1977. Each survey included a self-administered questionnaire with questions on smoking and antihypertensive drug treatment, measurements of height, weight and blood pressure and the determination of the serum cholesterol concentration. Multivariate analyses were performed by using Cox proportional hazard models.

SETTING

The provinces of North Karelia and Kuopio in eastern Finland

PARTICIPANTS

Men and women aged 45-64 years with no history of myocardial infarction or stroke at the time of the baseline survey were selected. In total 4333 men and 5270 women took part in this follow-up study.

RESULTS

The relative risk of coronary heart disease, stroke, cardiovascular disease and all-cause mortality increased with the increasing pulse pressure in individuals aged 45-64 years independent of the diastolic blood pressure level. Only in women with diastolic blood pressure > or = 95 mmHg was the relative risk of fatal stroke not statistically significant. After adjustment for systolic blood pressure, the positive association between mortality and increasing pulse pressure disappeared.

CONCLUSION

Increasing pulse pressure is a predictor of death from coronary heart disease, stroke, cardiovascular disease and all causes in men and women aged 45-64 years, but the increase in risk is entirely associated with the increase in systolic blood pressure.

Role of tapering in aortic wave reflection: hydraulic and mathematical model study

Pressure and flow have been measured simultaneously at six locations along the aorta of an anatomically correct 1:1 scale hydraulic elastic tube model of the arterial tree. Our results suggest a discrete reflection point at the level of the renal arteries based on (i) the quarter-wavelength formula and (ii) the comparison of foot-to-foot (c(ff)) and apparent phase velocity (c(app)). However, separation of the pressure wave into an incident and reflected wave at all six locations indicates continuous reflection: a reflected wave is generated at each location as the forward wave passes by. We did a further analysis using a mathematical transmission line model with a simple tapering geometry (length 50 cm, 31 and 11 mm proximal and distal diameter, respectively) for a low (0.32 ml/mmHg), normal (1.6 ml mmHg) and high (8 ml/mmHg) value of total arterial compliance. Using the quarter-wavelength formula, a discrete reflection point is found at x = 33 cm, the level of the renal arteries, independent of the value of total compliance. However, local analysis comparing c(ff) and c(app) does not reveal a marked reflection site, and the analysis of incident and reflected waves merely suggests a continuous reflection. We therefore conclude that the measured in vivo aortic wave reflection indices are the result of at least two interacting phenomena: a continuous wave reflection due to tapering, and local reflections arising from branches at the level of the diaphragm. The continuous reflection is hidden in the input impedance pattern. Using the quarter-wavelength formula or the classical wave separation theory, it appears as a reflection coming from a single discrete site, confusingly also located at the level of the diaphragm. Therefore, the quarter-wavelength formula and the linear wave separation theory should be used with caution to identify wave reflection zones in the presence of tapering, i.e., in most mammalian arteries.

Pathophysiology of Hypertension in the Elderly

The onset and progression of hypertension is associated with alterations in structure, function, and hemodynamics of the heart, vascular system, and other major organs. An understanding of the structural and functional changes in the cardiovascular system associated with this process would allow for early detection and the development of treatment strategies. In this paper, we focus on the anatomic alterations that accompany vascular aging and the resulting cardiovascular dynamics. Techniques to measure changes in cardiovascular dynamics and left ventricular performance are reviewed. The impact of therapeutic strategies on cardiovascular dynamics and left ventricular function are also discussed. (c)2000 by CVRR, Inc.

Special problems in the elderly

With aging, the heart, kidneys, liver, lungs, and brain lose mass. While not inherently impaired, the reserve capacity of the older individual to compensate for stress, metabolic derangement, and drug metabolism is increasingly limited. Functional disability occurs faster and takes longer to remediate, necessitating early preventive interventions.

Physiological doses of estradiol decrease nocturnal blood pressure in normotensive postmenopausal women

The effect of a 2-mo treatment with transdermal estradiol (50 microgram/day) versus placebo on 24 h of blood pressure rhythm was investigated in 18 normotensive healthy postmenopausal women. Whereas daytime blood pressure was not modified, nighttime blood pressure was reduced by estradiol. Estradiol magnified the nocturnal decrement of systolic (14.3 +/- 7.2 vs. 9.8 +/- 6.7 mmHg, P = 0. 0033), diastolic (11.6 +/- 5.0 vs. 7.5 +/- 7.3 mmHg, P = 0.028), and mean (10.8 +/- 5.6 vs. 7.2 +/- 4.5 mmHg, P = 0.011) blood pressure. As a consequence, the 24-h rhythm of mean blood pressure was restored in 50% of the subjects (P = 0.045) in whom it was absent and was amplified in the remaining 50% of the subjects. Body mass index was an independent determinant of blood pressure values being directly related to the amplitude of the 24-h mean blood pressure rhythm (r2 = 0.38; P = 0.0067). In normotensive postmenopausal women, physiological doses of estradiol amplify the nocturnal decline of blood pressure.

Relationship of blood pressure to cardiovascular death: the effects of pulse pressure in the elderly

PURPOSE

To investigate the relationship of systolic and diastolic blood pressure to fatal myocardial infarction, fatal stroke and other death related to cardiovascular diseases (CVD).

METHODS

The study was based on a prospective longitudinal study conducted by the Veterans Administration at the Boston Outpatient Clinic. Participants are male volunteers from the greater Boston area. Main outcome measures are fatal myocardial infarction, fatal stroke and other deaths related to cardiovascular diseases. The method of pooled logistic regression was used for statistical analysis.

RESULTS

For younger men (age 21-59), after adjusting for effects of other risk factors, when systolic and diastolic blood pressure were considered separately, SBP was predictive of cardiovascular death (SBP: RR = 1.23; 95% CI = (1.05, 1.45) per 10 mmHg of increase), and DBP showed a nonsignificant positive trend in relation to cardiovascular death (DBP: RR = 1.27; 95% CI = (0.95, 1.69) per 10 mmHg of increase). For older men (age 60-85), when SBP and DBP were considered separately, SBP (RR = 1.26; 95% CI = (1.02, 1.55) per 15 mmHg of increase) was directly related, but DBP (RR = 1.05; 95% CI = (0.83, 1.32) per 8 mmHg of increase) was not related to cardiovascular death. However, for the elderly group, when SBP and DBP were considered jointly in the regression model, then the regression coefficient of DBP (beta = -0.018, p = 0.30) was of approximately the same absolute magnitude as that of SBP (beta = 0.021, p = 0.02) but opposite in sign. For younger men, when SBP and DBP were considered jointly, SBP (beta = 0.021, p = 0.049) but not DBP (beta = -0.001, p = 0.953) was positively related to cardiovascular death.

CONCLUSIONS

We found that, for the elderly, pulse pressure (SBP-DBP) may be a more accurate predictor of cardiovascular death than either SBP or DBP alone. The relative risk per 35 mmHg of increase of pulse pressure, which equals the approximate interval from the 10th to the 90th percentile in the elderly group, is 2.1 with 95% CI = (1.1, 3.8). In younger subjects, SBP, but not DBP, is an independent predictor of fatal CVD.

Coupled systolic-ventricular and vascular stiffening with age: implications for pressure regulation and cardiac reserve in the elderly

OBJECTIVES

We tested the hypothesis that age-related arterial stiffening is matched by ventricular systolic stiffening, and that both enhance systolic pressure sensitivity to altered cardiac preload.

BACKGROUND

Arterial rigidity with age likely enhances blood pressure sensitivity to ventricular filling volume shifts. Tandem increases in ventricular systolic stiffness may also occur and could potentially enhance this sensitivity.

METHODS

Invasive left ventricular pressure-volume relations were measured by conductance catheter in 57 adults aged 19 to 93 years. Patients had normal heart function and no cardiac hypertrophy and were referred for catheterization to evaluate chest pain. Twenty-eight subjects had normal coronary angiography and hemodynamics, and the remaining had either systolic hypertension or coronary artery disease without infarction. Data recorded at rest and during transient preload reduction by inferior vena caval obstruction yielded systolic and diastolic left ventricular chamber and effective arterial stiffness and pulse pressure.

RESULTS

Left ventricular volumes, ejection fraction and heart rate were unaltered by age, whereas vascular load and stiffening increased (p < 0.008). Arterial stiffening (Ea) was matched by increased ventricular systolic stiffness (Ees): Ees=0.91 x Ea + 0.53, (r=0.50, p < 0.0001), maintaining arterial-heart interaction (Ea/Ees ratio) age-independent. Ventricular systolic and diastolic stiffnesses correlated (r=0.51, p < 0.0001) and increased with age (p < 0.03). Both ventricular and vascular stiffening significantly increased systolic pressure sensitivity to cardiac preload (p < 0.006).

CONCLUSIONS

Arterial stiffening with age is matched by ventricular systolic stiffening even without hypertrophy. The two effects contribute to elevating systolic pressure sensitivity to altered chamber filling. In addition to recognized baroreflex and autonomic dysfunction with age, combined stiffening could further enhance pressure lability with diuretics and postural shifts in the elderly.

What is the plasma cofactor required by diuretics for direct vascular relaxant effect in vitro?

OBJECTIVE

To determine the plasma cofactor which is required by diuretics (hydrochlorothiazide, chlorthalidone, indapamide, and furosemide) for direct vasorelaxant effects in vitro.

DESIGN

A randomized, double-blind, vehicle-control design was used to avoid experimenter bias.

METHODS

We plotted concentration-response curves for responses to hydrochlorothiazide, chlorthalidone, indapamide, and furosemide of male Wistar rat aortic rings in the presence of different bath solutions containing various plasma factors.

RESULTS

Plasma was found both to make possible and facilitate the vasodilator action of the diuretics tested by an action on the membrane and to decrease the action by binding the diuretics. The diuretics retained their vasorelaxant properties in Krebs solution alone, 30 min after having been incubated in a 50:50 solution of Krebs solution and plasma for 1 h. All four diuretics exerted significant vasorelaxant actions in Krebs solution-plasma, Krebs solution-serum, and Krebs solution plus human or bovine albumin (40 g/l) media. No vasorelaxant action was found in Krebs solution alone, Krebs solution plus denatured plasma, Krebs solution plus egg albumin, and Krebs solution plus insulin.

CONCLUSION

Albumin is the main cofactor required by the diuretics tested for direct relaxant action in vitro, and these findings may explain some of the contradictory evidence concerning this action in the literature.

Sphygmomanometrically determined pulse pressure is a powerful independent predictor of recurrent events after myocardial infarction in patients with impaired left ventricular function. SAVE investigators. Survival and Ventricular Enlargement

BACKGROUND

There is increasing evidence of a link between conduit vessel stiffness and cardiovascular events, although the association has never been tested in a large post-myocardial infarction patient population.

METHODS AND RESULTS

We evaluated the relationship between baseline pulse pressure, measured by sphygmomanometry 3 to 16 days after myocardial infarction, and subsequent adverse clinical events in the 2231 patients enrolled in the SAVE Trial. Increased pulse pressure was associated with increased age, left ventricular ejection fraction, female sex, history of prior infarction, diabetes, and hypertension and use of digoxin and calcium channel blockers. Over a 42-month period, there were 503 deaths, 422 cardiovascular deaths, and 303 myocardial infarctions. Pulse pressure was significantly related to each of these end points as a univariate predictor. In a multivariate analysis, pulse pressure remained a significant predictor of total mortality (relative risk, 1.08 per 10 mm Hg increment in pulse pressure; 95% CI, 1.00 to 1.17; P<.05) and recurrent myocardial infarction (relative risk, 1.12; 95% CI, 1.01 to 1.23; P<.05) after control for age; left ventricular ejection fraction; mean arterial pressure; sex; treatment arm (captopril or placebo); smoking history; history of prior myocardial infarction, diabetes, or hypertension; and treatment with beta-blockers, calcium channel blockers, digoxin, aspirin, or thrombolytic therapy.

CONCLUSIONS

These data provide strong evidence for a link between pulse pressure, which is related to conduit vessel stiffness, and subsequent cardiovascular events after myocardial infarction in patients with left ventricular dysfunction.

Hemodynamic patterns of age-related changes in blood pressure. The Framingham Heart Study

BACKGROUND

We attempted to characterize age-related changes in blood pressure in both normotensive and untreated hypertensive subjects in a population-based cohort from the original Framingham Heart Study and to infer underlying hemodynamic mechanisms.

METHODS AND RESULTS

A total of 2036 participants were divided into four groups according to their systolic blood pressure (SBP) at biennial examination 10, 11, or 12. After excluding subjects receiving antihypertensive drug therapy, up to 30 years of data on normotensive and untreated hypertensive subjects from biennial examinations 2 through 16 were used. Regressions of blood pressure versus age within individual subjects produced slope and curvature estimates that were compared with the use of ANOVA among the four SBP groups. There was a linear rise in SBP from age 30 through 84 years and concurrent increases in diastolic blood pressure (DBP) and mean arterial pressure (MAP); after age 50 to 60 years, DBP declined, pulse pressure (PP) rose steeply, and MAP reached an asymptote. Neither the fall in DBP nor the rise in PP was influenced significantly by removal of subsequent deaths and subjects with nonfatal myocardial infarction or heart failure. Age-related linear increases in SBP, PP, and MAP, as well as the early rise and late fall in DBP, were greatest for subjects with the highest baseline SBP; this represents a divergent rather than parallel tracking pattern.

CONCLUSIONS

The late fall in DBP after age 60 years, associated with a continual rise in SBP, cannot be explained by "burned out" diastolic hypertension or by "selective survivorship" but is consistent with increased large artery stiffness. Higher SBP, left untreated, may accelerate large artery stiffness and thus perpetuate a vicious cycle.

Atherosclerosis: risk factors and the vascular endothelium

The endothelium can respond to a local environment by releasing a variety of substances that regulate the level of vascular tone. One of the most important of these vasoregulatory substances is EDRF. The function of the endothelium is altered in a variety of pathologic and physiologic conditions. This review focused on the role of risk factors for atherosclerosis as it relates to EDRF. Atherosclerotic blood vessels respond abnormally on exposure to stimuli that release EDRF. It is now also apparent that this abnormal vascular response may precede the development of significant atherosclerosis and that normalization of the EDRF response with treatment is possible. Thus abnormal endothelium-dependent relaxation has been demonstrated in hypercholesterolemic patients with little or no evidence of coronary angiographic disease and in patients with hypertension before the development of atherosclerosis. The interaction between risk factors and the function of the vascular endothelium with development of atherosclerosis may become a useful focus for therapies that benefit patient outcomes.

Role of molecular regulation in vascular calcification

Calcium deposits account for most of the dry weight of atherosclerotic lesions. Previously considered uncommon, vascular calcification is now known to be present in 80% of significant lesions and in at least 90% of patients with coronary artery disease. Previously considered a passive process, it is increasingly recognized as an active, regulated process. Previously considered benign, it is now becoming recognized as a major risk factor for cardiovascular events, and a major contributor to systolic hypertension, heart failure, plaque rupture and stenosis. To confirm the similarity of vascular calcification with embryonic osteogenesis, we demonstrated the expression of bone morphogenetic protein in calcified human lesions, and we developed an in vitro model of vascular calcification that provides a useful experimental system for elucidating the molecular regulation of this process, which we have shown to include alkaline phosphatase induction and expression of bone matrix proteins and differentiation factors. Understanding the regulatory mechanisms of vascular calcification will allow future therapeutic approaches to prevent and possibly reverse this disease and its clinical consequences.