Biomedical subjects

E R Rietzschel

Publications and source records attributed to E R Rietzschel.

5 recordsLinked to original sources

PubMed2001

A comparison between systolic and diastolic pulse contour analysis in the evaluation of arterial stiffness.

Several methodologically independent measures of arterial stiffness derived from either the systolic or diastolic segments of the arterial pulse have been proposed. The exact nature of the large and small artery elasticity indices (C1 and C2, respectively) derived from diastolic pulse contour analysis remains largely unexplored, although C2 has controversially been termed to be "oscillatory" and "reflective." We investigated the relation between C2 and, respectively, a prototype of arterial reflectivity (ie, the augmentation index, AIx) and a covariate of arterial reflectivity (body height). A validated transfer function is used to transform a tonometrically obtained radial pressure wave into an ascending aortic pressure wave, from which AIx is derived using systolic pulse contour analysis. Diastolic pulse contour analysis using a modified Windkessel model is used to derive C1 and C2. One hundred subjects, who were free from atherothrombotic disease and 19 to 77 years of age, with a wide pressure range (97 to 186/52 to 104 mm Hg) were studied. Mean values of C1, C2, AIx, and body height were, respectively, 13.8+/-4.3 mL/mm Hgx10, 5.9+/-3.1 mL/mm Hgx100, 128.5+/-24.9%, and 169+/-9 cm. Coefficients of variation were 32.8% for C1, 33.3% for C2, and 6.7% for AIx. C2 was significantly and inversely correlated to AIx (r=-0.707, P<0.001). Both AIx and C2 were correlated to body height (r=-0.487, P<0.001, and r=0.514, P<0.001). In conclusion, the results of this study provide the first clinical evidence that validates a probable biophysical equivalent of the C2 element of a third-order, 4-element modified Windkessel model. We suggest that C2 is, at least in part, a measure of arterial wave reflectance. However, although short-term reproducibility of AIx is excellent, C2 showed markedly increased variability with the devices used.

Adult↗

PubMed2001

Interchangeability of carotid and femoral intima-media thickness in risk stratification.

BACKGROUND: Carotid intima-media thickness (c-IMT) is an intermediate phenotype not only for the local but also the global arteriosclerotic status, a concept which has been validated by its ability to act as a marker for future cardiovascular and cerebrovascular events. Whether the association between c-IMT and risk factors, distant atherosclerotic disease and prognosis are the sole prerogative of the carotid artery, or whether these findings can be extrapolated to other arterial sites is less well studied. In view of the concept of vascular heterogeneity, we measured the IMT in a muscular, lower extremity artery, the common femoral (f-IMT), and in elastic upper extremity artery, the common carotid, in apparently healthy individuals and explored the relationship with risk factors and the individuals 10-year cardiovascular (CV) risk, calculated using the Framingham systolic blood pressure equation. METHODS: A population of 156 apparently healthy normotensive Caucasian volunteers between 18 and 65 years was studied (mean age 43+/-13 years; 68 men, 88 women; mean arterial blood pressure 126 +/- 15/70 +/- 10 mmHg). The c-IMT and f-IMT were measured using a 10 MHz vascular linear array transducer at the far walls 1 to 2 centimetres proximal to the right common carotid and right common femoral artery bifurcations, respectively. Risk factors were assessed and the 10-year cardiovascular risk was calculated using the Framingham systolic blood pressure equation. RESULTS: The median c-IMT was 0.52 mm (interquartile range 0.45-0.62 mm) and f-INT was 0.52 mm (0.39-0.67). Both parameters were significantly correlated (r = 0.363; p < 0.01) and both were significantly correlated to the calculated 10-year CV risk (r = 0.579; p < 0.01 and r = 0.574; p < 0.01 for the carotid and c-IMT and f-IMT, respectively). Median risk was low: 2.11% (0.27-5.50). Although measures of agreement were higher for the f-IMT versus risk (0.47) than for the c-IMT versus risk (0.30), the former showed a significantly wider scatter with increasing age and with quartiles of CV risk. The c-IMT and f-IMT do not share determinant risk factors to the same extent and with only 20% of mutual variance explained, cannot be regarded as interchangeable. CONCLUSIONS: Although the c-IMT and f-IMT are significantly intercorrelated and correlate to the calculated 10-year CV risk, they are not interchangeable. While the f-IMT is less suited as a continuous variable for risk stratification in a low-risk population, our data suggest its possible use as a dichotomised risk marker.

Adolescent↗

PubMed2000

Aldosterone and vascular damage.

Although the aldosterone escape mechanism is well known, aldosterone has often been neglected in the pathophysiologic consequences of the activated renin-angiotensin-aldosterone system in arterial hypertension and chronic heart failure. There is now evidence for vascular synthesis of aldosterone aside from its secretion by the adrenal cortex. Moreover, aldosterone is involved in vascular smooth muscle cell hypertrophy and hyperplasia, as well as in vascular matrix impairment and endothelial dysfunction. The mechanisms of action of aldosterone may be either delayed (genomic) or rapid (nongenomic). Deleterious effects of aldosterone leading to vascular target-organ damage include (besides salt and water retention) decreased arterial and venous compliance, increased peripheral vascular resistance, and impaired autonomic vascular control due to baroreflex dysfunction.

Adrenal Cortex↗

PubMed1998

Inverse relationship between aldosterone and large artery compliance in chronically treated heart failure patients.

AIMS: The purpose of this study was to examine, in chronically treated heart failure patients vs control subjects, the influence of neurohumoral activation and aldosterone escape on arterial elastic behaviour, assessed by non-invasive mathematical lumped-parameter modelling of the compliance of the arterial system. METHODS AND RESULTS: Radial arterial pulse waves were recorded non-invasively for 30 s with an arterial tonometer sensor array in 13 chronic heart failure patients (mean age, 59 +/- 2.5 years) in New York Heart Association class II. The patients had been taking digoxin, furosemide, captopril and aspirin for more than 3 months. Thirteen healthy subjects (mean age, 50 +/- 4.0 years) acted as controls. Compliance of the proximal (aorta and major branches, C1) and distal parts (C2) of the circulation were derived from a third order four-element modified Windkessel model which can reproduce arterial pressure waveforms, including both exponential and oscillatory sections. Active renin, angiotensin II and aldosterone levels were determined on venous blood samples in the supine position and after 30 min active standing. There was decreased proximal (C1, 1.51 +/- 0.11 ml x mmHg(-1), P<0.01) and distal (C2, 0.050 +/- 0.011 ml x mmHg(-1)) arterial compliance in the chronic heart failure patients vs controls (C1, 1.71 +/- 0.16 ml x mmHg(-1); C2, 0.054 +/- 0.006 ml x mmHg(-1)). The chronic heart failure patients were characterized by an aldosterone escape phenomenon which was inversely correlated with the proximal arterial compliance in both supine (r= - 0.795, P=0.002) and standing (r= - 0.628, P=0.029) positions. CONCLUSIONS: In chronically treated heart failure patients with full angiotensin-converting enzyme-inhibition and diuretics, there is decreased compliance of the aorta and its major branches, which is inversely correlated with the aldosterone escape phenomenon.

Aldosterone↗

PubMed1995

Renin-angiotensin-aldosterone system, RR interval, and blood pressure variability during postural changes in borderline arterial hypertension.

This study aimed to examine the changes in RR interval and blood pressure (BP) variability and humoral factors during postural changes in borderline arterial hypertension. Twenty-nine patients (44 +/- 3 year; BP, 145 +/- 3/84 +/- 3 mm Hg) with borderline hypertension and a control group of 38 subjects (35 +/- 2 year; BP, 123 +/- 3/70 +/- 2 mm Hg) underwent power spectrum analysis of RR interval and BP (low frequency (LF), 0.05 to 0.15 Hz; high frequency (HF), 0.15 to 0.40 Hz) in the supine and standing positions. Concentrations of plasma renin activity, angiotensin II, and aldosterone in supine and standing positions had been determined in the hypertensive group. Borderline hypertensives are characterized by higher oscillations of systolic and diastolic BP, but not of RR interval in the supine position versus the control group. Low frequency and HF components of systolic and diastolic BP expressed as absolute data are also significantly higher in borderline hypertensives. Moreover, standing tended to increase the LF/HF ratio of both RR interval and BP variability compared to controls. The standing position was able to further activate the LF but not the HF component of BP variability. In borderline hypertension renin release during postural changes correlated well with the decrease in the power of the HF vagal component of RR interval variability (r = -0.70, P < .001) and with the increase of the LF component of diastolic blood pressure variability (r = 0.43, P = .03). In conclusion, our results indicate that in borderline arterial hypertension, LF and HF oscillations of BP are already significantly increased at rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗