William F. Graettinger

Validation of portable noninvasive blood pressure monitoring devices: Comparisons with intra-arterial and sphygmomanometer measurements

We have evaluated the accuracy of measurements provided by different types of portable automatic blood pressure monitoring devices by comparing them with intra-arterial and mercury sphygmomanometer measurements in 25 hospitalized patients. Systolic blood pressure values with portable devices that use auscultatory or oscillometric methods of measurement correlated significantly with intra-arterial values (r = 0.74 and 0.89; p less than 0.001 for both); similarly, diastolic values correlated significantly (r = 0.86 and 0.81; p less than 0.001 for both). Compared with intra-arterial measurements, there was a slight tendency for the portable devices to underestimate systolic blood pressure and overestimate diastolic blood pressure. Correlations between auscultatory or oscillometric measurements and sphygmomanometer measurements in these patients were also significant; moreover, the absolute blood pressure values obtained with the portable devices were almost identical to those with the sphymomanometer. In a further group of 12 volunteers, auscultatory and oscillometric values correlated very closely with simultaneously measured sphygmomanometer values for both systolic (r = 0.99 and 0.98) and diastolic (r = 0.96 and 0.94) blood pressures. An auscultatory device that uses continuous ECG R wave gating for Korotkoff sounds was also found to be highly accurate. Thus we have found that automated portable devices that use either auscultatory or oscillometric methods of measurement provide reliable blood pressure values.

Dependency of arterial compliance on circulating neuroendocrine and metabol factors in normal subjects

Reduced arterial compliance is now recognized as a feature of hypertension. Similarly, metabolic factors such as insulin, catecholamines and lipids are also associated with hypertension. This study explores the possibility that these neuroendocrine and metabolic factors may separately influence arterial compliance. Proximal compliance (aorta and large arteries) and distal compliance (small arteries and arterioles) were measured in 57 volunteers (30 hypertensive and 27 normotensive subjects, mean age 45 years). Compliance was quantified by analysis of arterial pulse wave contours obtained intraarterially together with hemodynamic estimates. Proximal compliance correlated with plasma insulin (r = -0.49; p less than 0.001), norepinephrine (r = -0.50; p less than 0.002), triglycerides (r = -0.39; p less than 0.01), total cholesterol (r = -0.33; p = 0.02) and high-density lipoprotein cholesterol (HDL) (r = 0.37; p less than 0.02). Similarly, distal compliance correlated with insulin (r = -0.37; p less than 0.02), triglycerides (r = -0.39; p less than 0.01), total cholesterol (r = -0.38; p less than 0.01) and HDL (r = 0.51, p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Heredity and hypertension: Impact on metabolic characteristics

This study was performed to evaluate the possible role of heredity in the clinical characteristics of hypertension. Metabolic, endocrine, and renal measurements were compared in subjects with normal blood pressure who had a family history of hypertension (n = 60) with those of subjects with normal blood pressure who did not have a family history of hypertension (n = 48). The groups were matched for age (mean, 44 +/- 2 years and 45 +/- 2 years) and blood pressure (127 +/- 1/77 +/- 1 mm Hg and 127 +/- 2/77 +/- 1 mm Hg). The following parameters were higher in the patients with a family history of hypertension than in those without. Plasma insulin concentrations (14.1 +/- 1.1 vs 10.8 +/- 1.0 microU/ml; p less than 0.05), insulin-glucose ratio (0.15 +/- 0.01 vs 0.11 +/- 0.010; p less than 0.05), norepinephrine concentrations (315 +/- 24 pg/ml vs 208 +/- 20 pg/ml; p less than 0.01), plasma renin activity (2.1 +/- 0.2 ng Angl/ml/hr vs 1.6 +/- 0.2 ng Angl/ml/hr; p less than 0.02), total cholesterol levels (217 +/- 8 mg/dl vs 197 +/- 0.3 mg/dl; p less than 0.05), creatinine clearance (125 +/- 9 ml/min vs 96 +/- 8 ml/min; p less than 0.01), and albumin excretion rate (3.2 +/- 0.3 micrograms/min vs 2.6 +/- 0.3 micrograms/min; p = 0.1). Moreover, patients with a family history of hypertension had smaller increases in systolic blood pressure during treadmill exercise (55 +/- 3 mm Hg vs 64 +/- 3 mm Hg; p less than 0.03). There were no differences in echocardiographic left ventricular mass index between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular diastolic filling alterations in normotensive young adults with a family history of systemic hypertension

To characterize the cardiovascular consequences of a history of hypertension in first-degree relatives in normotensive young adults, 72 normotensive (diastolic blood pressure [BP] less than 90 mm Hg) healthy volunteers (age 18 to 30 years) were studied with 2 dimensionally guided M-mode echocardiography, pulsed Doppler echocardiography, and 2-hour automated BP monitoring. Of the 72 subjects, 19 (12 men and 7 women) had a family history of hypertension and were compared with 19 subjects without a family history of hypertension who were matched for systolic BP and gender. There were no detectable differences in 2-hour average BP, left ventricular (LV) mass or wall thickness, or echocardiographic systolic functional indexes between subjects with and without a family history of hypertension. Doppler-derived diastolic functional indexes demonstrated more prominent late diastolic filling in subjects with a family history of hypertension. Late diastolic transmitral flow time and flow velocity integral were greater (132 +/- 24 vs 117 +/- 17 ms, p less than 0.05; and 2.5 +/- 0.7 vs 1.9 +/- 0.5 cm, p less than 0.01, respectively). To measure possible gender-related effects of a family history of hypertension, the men and women were analyzed separately. The 12 men with a family history of hypertension had greater peak late (40 +/- 0.9 vs 31 +/- 0.8 cm/s, p less than 0.02) and ratio of late-to-early (0.64 +/- 0.19 vs 0.46 +/- 0.10, p less than 0.01) transmitral flow velocities and greater late transmitral flow velocity integrals (2.6 +/- 0.8 vs 1.9 +/- 0.5 cm, p less than 0.05) than the matched male control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Antihypertensive effects of β-blockers administered once daily : 24-hour measurements

Whole-day automated ambulatory blood pressure (BP) monitoring was used to assess the duration of the antihypertensive actions of the beta-blockers atenolol (50 to 100 mg; n = 20) and acebutolol (400 to 800 mg; n = 19) each given once daily at 9 AM. When compared with its pretreatment 24-hour average, atenolol decreased diastolic BP by 10 +/- 2 mm Hg (p less than 0.01) and systolic BP by 12 +/- 2 mm Hg (p less than 0.01). Acebutolol decreased the 24-hour diastolic BP by 11 +/- 1 mm Hg (p less than 0.01) and systolic BP by 13 +/- 2 mm Hg (p less than 0.01). More specifically, a comparison of the two drugs during the final 6 hours (3 AM to 9 AM) of the dosing interval showed that the mean decrease in diastolic BP of 10.2 +/- 1.5 mm Hg with acebutolol was greater (p less than 0.05) than the decrease of 6.2 +/- 1.3 mm Hg with atenolol. Moreover, this final 6-hour effect of atenolol was less (p less than 0.01) than that observed during the first 18 hours of the day. The late effects of acebutolol did not change significantly from its early effects. The two agents also differed in their trough (final 2-hour decrease in diastolic BP) and peak (maximum 2-hour decrease in diastolic BP) effects: for atenolol the peak-to-trough difference was 7.8 +/- 3.1 mm Hg (p less than 0.05), whereas for acebutolol it was 3.8 +/- 4.2 mm Hg (N.S.). This study confirms the efficacy of atenolol and acebutolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler predictions of pulmonary artery pressure, flow, and resistance in adults.

We examined the accuracy of noninvasive predictions of pulmonary artery pressure (P), flow (Q), and resistance (R) by means of main pulmonary artery blood velocities and diameters measured with Doppler echocardiography (DE). The ratio of noninvasive acceleration time to ejection time (An) was correlated to invasively determined mean pulmonary artery pressure (Pl) and resistance (Rl). Noninvasive flows were correlated to thermodilution flows (Ql). Simultaneous invasive and noninvasive measurements were made in nine adult patients (ages = 22 to 73 years). The results were: Pl = 87 - 152An, r = 0.90, SEE = 7 mm Hg, p less than 0.05; Rl = 899 - 1722An, r = 0.79, SEE = 121 dynes X sec X cm-5, p less than 0.05; and Ql = -0.3 + 1.21Qn, r = 0.95, SEE = 0.81 L X min-1, p less than 0.05. We then used these equations prospectively to predict Pl, Rl, and Ql in 21 of 25 (83% technically adequate) consecutive patients. Pl, Rl, and Ql ranged from 10 to 35 mm Hg, 39 to 456 dynes X sec X cm-5, and 3.51 to 8.39 L X min-1, respectively. Results were: Pl = 0.80P + 3, r = 0.72, SEE = 6 mm Hg, p less than 0.05; Rl = 0.75R - 12, r = 0.64, SEE = 77 dynes X sec X cm-5, p less than 0.005; and Ql = 0.87Q + 0.38, r = 0.83, SEE = 0.86 L X min-1, p less than 0.05. These results suggest that DE predictions of pulmonary artery pressure, flow, and resistance correlate significantly with values subsequently obtained at catheterization.

Impact of left ventricular hypertrophy on blood pressure responses to exercise

It is claimed that exaggerated blood pressure (BP) responses to exercise are predictive of future hypertension and may also be indicative of left ventricular (LV) hypertrophy. The relation between LV hypertrophy and maximal exercise BP was examined in 35 normal male volunteers and 65 untreated hypertensive male patients. Multiple stepwise regression analysis revealed that preexercise systolic BP was the major determinant of maximal exercise systolic BP (r = 0.52; p less than or equal to 0.0001), indicating that higher baseline BP predicted higher exercise BP. However, hypertensive patients with LV hypertrophy had the smallest increases in systolic BP with exercise. Accordingly, there was an inverse relation between LV muscle mass and systolic BP responses to exercise in these patients (r = -0.34; p = 0.005). When compared with normotensive subjects, hypertensive patients had lower measures of maximal oxygen uptake and exercise heart rates (p = 0.01). This may indicate lower cardiac performance at maximal exercise and explain the reduced capacity of hypertensive patients with LV hypertrophy to increase systolic BP with exercise. Neither baseline nor exercise BPs correlated with LV mass; instead, the model of regression analysis indicated that body weight was the principal determinant of LV mass. Contrary to previous reports, exaggerated exercise BPs were not associated with LV hypertrophy in hypertensive or normotensive patients.

Diastolic blood pressure as a determinant of Doppler left ventricular filling indexes in normotensive adolescents.

Alterations in left ventricular filling can occur with aging and in patients with hypertension, ischemic heart disease, congestive and hypertrophic cardiomyopathy and congenital heart disease. This study examines the effects of blood pressure on left ventricular diastolic filling indexes measured by Doppler ultrasound technique in 47 young normotensive adolescents (mean age 13 years). Left ventricular filling was assessed by Doppler peak early and late diastolic transmitral flow velocities, early and late diastolic flow velocity integrals and early diastolic deceleration. Systolic blood pressure did not correlate with any of the Doppler filling indexes, although it was related to echocardiographic left ventricular mass (r = 0.44, p less than 0.005). Diastolic blood pressure did not correlate with left ventricular mass; however, it was inversely related to peak early diastolic flow velocity (r = -0.44, p less than 0.005), early diastolic flow velocity integral (r = -0.40, p less than 0.01) and early diastolic deceleration (r = -0.32, p less than 0.05). The ratio of late to early peak filling (A/E) was directly related to diastolic blood pressure (r = 0.48, p less than 0.001). Examination of electrocardiograms showed that there was a stronger correlation between A/E ratio and diastolic blood pressure (r = 0.63) in 22 subjects with bimodal P waves in lead V1 than in subjects with unimodal P waves (r = 0.45).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular and metabolic characteristics of hypertension

Hypertension is now seen as a broader condition than high blood pressure alone. Large-scale epidemiologic studies have established that high blood pressure is associated with an increased risk of cardiovascular events, but clinical trials of antihypertensive therapy have shown an inconsistent reduction in major cardiovascular endpoints. Importantly, the incidence of coronary disease has been reduced to only a small extent, suggesting that factors beyond high blood pressure are important in the genesis of atherosclerotic disease in hypertensive patients. It is evident, for example, that patients with hypertension have an exaggerated vulnerability to the consequences of lipid abnormalities. Moreover, it has recently been established that hypertension is characterized by insulin resistance and altered glucose tolerance. As a result, high plasma concentrations of insulin produce proliferative effects on vascular smooth muscle and connective tissue, and they may adversely affect the lipid profile. The left ventricle is also involved in hypertension--independent of blood pressure. There is growing evidence that there are increases in the muscle mass of the left ventricle and changes in its diastolic filling characteristics at the very early stages of hypertension. The arterial circulation is similarly involved, for alterations in structure or function, reflected by diminished arterial compliance, can be demonstrated prior to the appearance of clinical hypertension. Treatment designed to protect hypertensive patients from cardiovascular events must not only be based on blood pressure, but must take into account all the components of the hypertension syndrome.

Metabolic characteristics of hypertension: Importance of positive family history

This study was performed to compare metabolic and endocrine characteristics of untreated hypertensive patients and normal controls. Measurements were made in age-matched, body mass index (BMI) matched, normotensive patients with (n = 40; age = 53; BMI = 28) and without (n = 39; age = 54; BMI = 27) a family history of hypertension and hypertensive patients with (n = 38; age = 53; BMI = 28) and without (n = 25; age = 54; BMI = 29) a family history of hypertension. Norepinephrine, renin activity, and total cholesterol blood concentrations were similar in normotensive patients with a positive family history of hypertension and in hypertensive patients with or without a family history. Similarly, there were no differences in plasma insulin concentrations or insulin/glucose ratios between the normotensive patients with a family history of hypertension and hypertensive patients with or without a family history. But in all three groups the values were significantly greater (at least p < 0.05 for each) than in the normotensive patients without a family history. Increases in systolic blood pressure during treadmill testing were 51 +/- 4 mm Hg in the normotensive patients with a family history, 50 +/- 3 mm Hg in hypertensives with a family history, and 45 +/- 5 mm Hg in hypertensives without a family history; these changes were all less (p < 0.05 for each) than in normotensives without a family history (65 +/- 3 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)