Central blood pressure reflects left ventricular load, while brachial blood pressure reflects arterial damage

Central and brachial pulse pressure predicts cardiovascular and renal events in treated hypertensive patients

PURPOSES

Central blood pressure is a stronger predictor of cardiovascular prognosis rather than brachial blood pressure. The reflection wave reaches the abdominal aorta sooner than ascending aorta. Thus, the contribution of central pulse pressure (cPP) to renal events may differ from that of cardiovascular events.

METHODS

The subanalysis of the ABC-J II study was performed. Subjects were 3434 treated hypertensive patients with a mean follow-up of 4.7 years. Left ventricular hypertrophy, an index of cardiovascular risk, correlated with cPP better than central systolic blood pressure in this cohort. The contribution of brachial pulse pressure (bPP) and cPP to cardiovascular and renal events was analysed.

RESULTS

Cox proportional-hazard analysis revealed that sex (p < 0.001), height (p < 0.05), history of cardiovascular diseases (p < 0.001), number of antihypertensive drugs (p < 0.05), and cPP (p < 0.05) contributed to cardiovascular events. However, Cox proportional-hazard analysis disclosed that baseline serum creatinine (p < 0.001) and bPP (p < 0.05) predicted renal events. After adjusting for the history of cardiovascular diseases, Cox regression demonstrated only sex as a significant predictor of cardiovascular events. After adjusting for baseline serum creatinine, no parameters were shown to predict renal events.

CONCLUSIONS

The present findings support our previous data that the absence of cardiovascular or renal diseases is an important determinant for event-free survival, and suggest that cPP and bPP contribute to cardiovascular and renal events in treated hypertensive patients.

High-frame-rate A-mode ultrasound for calibration-free cuffless carotid pressure: feasibility study using lower body negative pressure intervention

PURPOSE

Existing technologies to measure central blood pressure (CBP) intrinsically depend on peripheral pressure or calibration models derived from it. Pharmacological or physiological interventions yielding different central and peripheral responses compromise the accuracy of such methods. We present a high-frame-rate ultrasound technology for cuffless and calibration-free evaluation of BP from the carotid artery. The system uses a pair of single-element ultrasound transducers to capture the arterial diameter and local pulse wave velocity (PWV) for the evaluation of beat-by-beat BP employing a novel biomechanical model.

MATERIALS AND METHODS

System's functionality assessment was conducted on eight male subjects (26 ± 4 years, normotensive and no history of cardiovascular risks) by perturbing pressure via short-term moderate lower body negative pressure (LBNP) intervention (-40 mmHg for 1 min). The ability of the system to capture dynamic responses of carotid pressure to LBNP was investigated and compared against the responses of peripheral pressure measured using a continuous BP monitor.

RESULTS

While the carotid pressure manifested trends similar to finger measurements during LBNP, the system also captured the differential carotid-to-peripheral pressure response, which corroborates the literature. The carotid diastolic and mean pressures agreed with the finger pressures (limits-of-agreement within ±7 mmHg) and exhibited acceptable uncertainty (mean absolute errors were 2.4 ± 3.5 and 2.6 ± 4.0 mmHg, respectively). Concurrent to the literature, the carotid systolic and pulse pressures (PPs) were significantly lower than those of the finger pressures by 11.1 ± 9.4 and 11.3 ± 8.2 mmHg, respectively (p < .0001).

CONCLUSIONS

The study demonstrated the method's potential for providing cuffless and calibration-free pressure measurements while reliably capturing the physiological aspects, such as PP amplification and dynamic pressure responses to intervention.

Associations between measurements of central blood pressure and target organ damage in high-risk patients

Background

It is not well-known which components of central blood pressure (CBP) are more influential to target organ damage (TOD). This study aimed to determine the relationship between CBP measurements and various types of TOD in high-risk patients.

Methods

A total of 148 patients who had documented atherosclerotic cardiovascular disease or its multiple risk factors were prospectively enrolled. CBP was measured by using applanation tonometry of the radial artery. The following nine TOD parameters were evaluated: left ventricular mass index, relative wall thickness, septal e′ velocity, septal E/e′, brachial-ankle pulse wave velocity, ankle-brachial index, estimated glomerular filtration rate, urine protein and obstructive coronary artery disease.

Results

The mean age of the study population was 67.1 ± 9.0 years and 108 (73 %) were male. Among four CBP measurements (systolic, diastolic, mean, and pulse pressures), central pulse pressure (CPP) was associated with the largest number of TOD parameters. As CPP increased, the number of TOD increased (P = 0.010), but this association was not observed in other CBP measurements (P > 0.05 for each).

Conclusions

CPP had a stronger correlation with TOD than other CBP measurements. Non-invasive CPP could be a useful indicator for predicting TOD in patients at high coronary risk.

Prevalence of Hypertension Defined by Central Blood Pressure Measured Using a Type II Device in a Nationally Representative Cohort

OBJECTIVES

Central blood pressure (BP) can be used to define hypertension. A central BP approach may be more sensitive than a conventional brachial BP approach in detecting hypertension. We aimed to compare the 2 approaches in estimating the prevalence hypertension in a nationally representative population.

METHODS

A total of 2,742 adults older than 19 years participated in the 2013-2016 National Nutrition and Health Survey in Taiwan. Central and brachial BP were simultaneously measured using a cuff-based stand-alone central BP monitor purporting to measure invasive central BP (type II device). Central hypertension was defined by central systolic (SBP)/diastolic BP (DBP) ≥130 or 90 mm Hg or using antihypertensive medications, and brachial hypertension was defined by brachial SBP/DBP ≥140 or 90 mm Hg or using antihypertensive medications.

RESULTS

The World Health Organization-standardized and national weighted prevalence rates of central hypertension were 27.95% and 32.48%, respectively, and both were significantly higher than those of brachial hypertension (20.80% and 25.43%, both P < 0.001). The national weighted prevalence rates of concordant central and brachial hypertension, concordant central and brachial nonhypertension, isolated central hypertension, and isolated brachial hypertension were 25.13%, 67.22%, 7.35%, and 0.30%, respectively. Most subjects with the isolated central hypertension (97%) were within the range of brachial prehypertension, but only 38.0% of subject with brachial prehypertension had central hypertension.

CONCLUSION

Almost one-third of a nationally representative population had hypertension detected by a central BP approach. Hypertension detection using a conventional brachial BP approach may underestimate the prevalence of hypertension and result in a less effective hypertension control.

Evaluation of the reduction in central and peripheral arterial blood pressure following an oral glucose load

The clinical significance of measuring central arterial blood pressure has been recently discussed. Although the postprandial reduction in blood pressure is well known, postprandial changes in central blood pressure have not been intensively studied. The present study investigated differences in the reduction of central and peripheral arterial blood pressure after administration of an oral glucose load.An oral glucose tolerance test (75 g) was performed in 360 participants in our physical checkup program. Brachial and central systolic blood pressures were assessed before and after the glucose load. Central arterial blood pressure was measured noninvasively using an automated device.The mean age was 53.6 ± 8.2 years. Both brachial (127.9 ± 17.7 to 125.0 ± 16.3 mm Hg) and central arterial blood pressures were significantly decreased after an oral glucose load (118.9 ± 17.9 to 112.8 ± 16.8 mm Hg). The reduction in blood pressure was greater in central (7.3 ± 11.5 mm Hg) than in brachial blood pressure measurements (3.4 ± 11.3 mm Hg, P < .001). Extreme blood pressure reduction (>20 mm Hg) was recorded more frequently in central (n = 43, 12.3%) than brachial blood pressure measurements (n = 20, 5.6%).An oral glucose load decreases both central and brachial systolic blood pressure, with more pronounced effects on central blood pressure. Postprandial reductions in blood perfusion of the important organs such as the brain may be underestimated when postprandial BP reduction is assessed using brachial BP measurements.

Carotid intima-media thickness is a novel predictor of new onset of hypertension in normotensive subjects

Increased carotid intima-media thickness (IMT) in individuals without hypertension might indicate other factors promoting the atherosclerotic process that are often simultaneously clustered in individuals. The present study tested the hypothesis that carotid IMT predicts new onset of hypertension in the normotensive subjects.A total of 867 participants were enrolled from our yearly physical checkup program and their carotid IMT was measured. After a baseline examination, the subjects were followed up for a median of 1091 days with the endpoint being the development of hypertension.At baseline, the carotid IMT value was 0.75 ± 0.16 mm. Hypertension developed in 184 subjects during the follow-up (76.9/1000 person-years). The incidence of hypertension was increased across the tertiles of the carotid IMT value (39.6, 70.0, and 134.5/1000 person-years in the first, second, and third tertiles, respectively, P < .001 by log-rank test). Multivariate Cox-hazard analysis after adjustment identified carotid IMT, taken as a continuous variable, as a significant predictor of new-onset hypertension (hazard ratio = 7.08, 95% confidence interval = 3.06-15.39). Furthermore, multivariate linear regression analyses indicated a significant correlation between the carotid IMT at baseline and yearly increases in systolic blood pressure during the follow-up period (β = 0.189, P < .001).Carotid IMT is an independent predictor of hypertension onset in normotensive subjects. The findings also suggested a close association between increased carotid IMT and blood pressure.

Use of Electrocardiography to Predict Future Development of Hypertension in the General Population

Cardiac muscle responds to increased afterload by developing hypertrophy. During the early stages of hypertension, the heart can be transiently, but frequently, exposed to increased afterload. This study was designed to test the hypothesis that left ventricular hypertrophy (LVH) assessed by electrocardiography (ECG) can be used to predict future development of hypertension.Sokolow-Lyon voltage and Cornell product were calculated using ECG in 5770 normotensive participants who visited our hospital for a physical checkup (age 52.7 ± 11.3 years). LVH was defined as a Sokolow-Lyon voltage of >3.8 mV or a Cornell product of >2440 mm × ms. After baseline examination, participants were followed up with the endpoint being the development of hypertension.During the median follow-up period of 1089 days (15,789 person-years), hypertension developed in 1029 participants (65.2/1000 person-years). A Kaplan-Meier analysis demonstrated a significantly higher incidence of hypertension in participants with LVH than in those without LVH as assessed by Sokolow-Lyon voltage or Cornell product (P < 0.0001 for both). The hazard ratios for incident hypertension in participants with LVH defined by Sokolow-Lyon voltage and Cornell product were 1.49 (95% confidence interval [CI] 1.16-1.90, P < 0.01) and 1.34 (95% CI 1.09-1.65, P < 0.01), respectively, after adjustment for possible risk factors. Furthermore, in multivariable Cox hazard analysis, where Sokolow-Lyon voltage and Cornell product were taken as continuous variables, both indices were independent predictors of future hypertension (P < 0.0001).Both Sokolow-Lyon voltage and Cornell product are novel predictors of future development of hypertension in the general population.