Differences in pulse pressure day variability between the brachial artery and the aorta in healthy subjects

Superiority of 24-Hour Aortic Over 24-Hour Brachial Pressure to Associate With Carotid Arterial Damage on the Basis of Pressure Amplification Variability: the SAFAR Study

BACKGROUND

Evidence suggests marginal superiority of static aortic systolic blood pressure (aSBP) compared with brachial SBP regarding the association with organ damage and prognosis of cardiovascular disease. The noninvasive 24-hour aSBP assessment is feasible and associates better with presence of left ventricular hypertrophy compared with 24-hour brachial systolic blood pressure. We aimed at comparing the association of 24-hour aSBP and 24-hour brachial systolic blood pressure with indices of arterial damage and examining the role of 24-hour SBP amplification variability (within-subjects' SD) in this association.

METHODS

Consecutive subjects referred for cardiovascular disease risk assessment underwent 24-hour aortic and brachial ambulatory BP monitoring using a validated oscillometric device (Mobil-O-Graph). Arterial damage was assessed by carotid intima-media thickness and detection of carotid and femoral atheromatosis (plaque presence).

RESULTS

Cross-sectionally 501 individuals (aged 54±13 years, 57% men, 80% hypertensives) were examined. Multivariable analysis revealed superiority of 24-hour aSBP regarding the association with intimal-medial thickness, carotid hypertrophy and carotid-but not femoral-atheromatosis. In receiver operator characteristics analysis, 24-hour aBP displayed a higher discriminatory ability-compared to 24-hour brachial systolic blood pressure-for the detection of both carotid hypertrophy (area under the curve, 0.662 versus 0.624, P<0.05) and carotid atheromatosis (area under the curve, 0.573 versus 0.547, P<0.05). This effect was more prominent in individuals with above-median 24-hour SD of SBP amplification.

CONCLUSIONS

Our results suggest that 24-hour aSBP assessment may be of significant value in clinical practice to detect site-specific arterial damage on the basis of pressure amplification variability and should be prospectively examined in clinical trials.

Mechanisms of pulse pressure amplification dipping pattern during sleep time: the SAFAR study

The difference in pulse pressure (PP) between peripheral arteries and the aorta, called pulse pressure amplification (PPamp), is a well-described physiological phenomenon independently associated with cardiovascular events. Recent studies suggest that it exhibits circadian variability. Our aim was to detect the factors associated with the circadian variability of PPamp. In 497 consecutive subjects (aged 54 years, 56.7% male, 79.7% hypertensives), we assessed the circadian pattern of peripheral and central arterial hemodynamics by 24-hour evaluation of brachial and aortic blood pressure (BP), augmentation index (AI), and pulse wave velocity (PWV) using a validated oscillometric device (Mobil-O-Graph). All parameters exhibited a circadian variation. Sleep dipping (decrease) pattern was observed for PPamp, brachial and aortic systolic BP, mean BP, and PWV, whereas a rising pattern (higher sleep than wake values) was observed for brachial PP, aortic PP, and AI. The factors independently associated with the less sleep dipping in PPamp were older age, lower height, the use of antihypertensive medication, and sleep decrease in arterial stiffness (PWV), whereas female gender, the presence of hypertension, sleep increase of pressure wave reflections (AI), sleep decrease in heart rate, and mean BP were associated with a greater sleep-dipping in PPamp. These data provide further pathophysiological understanding of the mechanisms leading to PPamp dipping. Several implications regarding the clinical use of the aortic and brachial BP, especially during sleep time, are raised that should be addressed in future research.

Pulse pressure waveform estimation using distension profiling with contactless optical probe

The pulse pressure waveform has, for long, been known as a fundamental biomedical signal and its analysis is recognized as a non-invasive, simple, and resourceful technique for the assessment of arterial vessels condition observed in several diseases. In the current paper, waveforms from non-invasive optical probe that measures carotid artery distension profiles are compared with the waveforms of the pulse pressure acquired by intra-arterial catheter invasive measurement in the ascending aorta. Measurements were performed in a study population of 16 patients who had undergone cardiac catheterization. The hemodynamic parameters: area under the curve (AUC), the area during systole (AS) and the area during diastole (AD), their ratio (AD/AS) and the ejection time index (ETI), from invasive and non-invasive measurements were compared. The results show that the pressure waveforms obtained by the two methods are similar, with 13% of mean value of the root mean square error (RMSE). Moreover, the correlation coefficient demonstrates the strong correlation. The comparison between the AUCs allows the assessment of the differences between the phases of the cardiac cycle. In the systolic period the waveforms are almost equal, evidencing greatest clinical relevance during this period. Slight differences are found in diastole, probably due to the structural arterial differences. The optical probe has lower variability than the invasive system (13% vs 16%). This study validates the capability of acquiring the arterial pulse waveform with a non-invasive method, using a non-contact optical probe at the carotid site with residual differences from the aortic invasive measurements.