Elsevier

Atherosclerosis

Volume 210, Issue 1, May 2010, Pages 268-273
Atherosclerosis

Dysfunctional central hemodynamic regulation after daily meal intake in metabolic syndrome

https://doi.org/10.1016/j.atherosclerosis.2009.11.003Get rights and content

Abstract

Objective

Postprandial hyperlipidemia and insulin resistance play roles in the development of atherosclerosis in metabolic syndrome (MetS); however, the clinical significance of postprandial hemodynamic variables in this condition is still in question. The aim of this study was to investigate hemodynamic and metabolic indicators related to MetS after a mixed meal (Calorie mate, 500 kcal).

Methods

Of 107 participants undergoing this investigation, 24 fulfilled ATPIII criteria for MetS. The remaining 83 subjects were controls. Both the augmentation index (AI) and late systolic blood pressure in the radial artery (rSBP2) as an index of central blood pressure were monitored using HEM-9000AI (Omron Healthcare, Kyoto, Japan) until 240 min after meal intake.

Results

Both AI and rSBP2 showed significant decreases after meal intake in both groups. Changes in postprandial AI showed a similar trend in the groups. rSBP2 reduction 60 min after meal ingestion was also comparable, −7.5 ± 2.3 mmHg in MetS; −7.8 ± 0.9 mmHg in control; however, delta rSBP2-120, the degree of rSBP2 reduction 120 min after meal ingestion comparing the fasting level, showed a significant difference between 2 groups, −0.5 ± 2.0 mmHg in MetS; −5.3 ± 0.9 mmHg in control, P < 0.02. Stepwise regression analysis revealed low-density-lipoprotein cholesterol (β = 0.333, P = 0.001), high-density-lipoprotein cholesterol (β = −0.209, P < 0.05) and systolic blood pressure (β = −0.377, P < 0.001) as independent variables for determining delta rSBP2-120.

Conclusion

Subjects with MetS exhibit signs of blunted rSBP2 (= central blood pressure) regulation after food intake. Dysfunctional postprandial hemodynamic regulation is another feature of MetS that may contribute to the progression of cardiovascular disease.

Introduction

There is accumulative evidence that central aortic pressure is more relevant than peripheral pressure, i.e., brachial blood pressure (BP), to predict cardiovascular risk [1], [2], [3]. In most clinical settings, brachial BP, which is approximately 5–30 mmHg higher than in the aorta, is usually measured as a surrogate parameter for the evaluation and management of central aortic pressure although this difference is thought to be important because the heart and brain are exposed to aortic, and not to brachial pressure. Non-invasive methods, such as applanation tonometry to assess carotid [1] or radial artery waveforms [2], have been employed to evaluate central aortic pressure, instead of direct catheter insertion into the ascending aorta [3]. Recently, Takazawa et al. [4] demonstrated the close relationship between ascending aortic pressure directly assessed by a catheter method and late systolic BP in the radial artery (rSBP2) by assessing radial arterial pulse waves using a newly developed automated tonometric system (HEM-9000AI; Omron Healthcare Co., Ltd., Kyoto, Japan). We employed these indices, an augmentation index of radial artery and rSBP2, as surrogate markers of arterial stiffness and central BP, respectively, in this study.

Metabolic syndrome (MetS) is a clustering of cardiovascular risk factors, such as impaired glucose metabolism, abdominal fat accumulation, dyslipidemia and elevated blood pressure, and is thought to be relevant to insulin resistance, which influences not only fasting but also postprandial glucose and lipid metabolism [5]. In other words, it is widely accepted that postprandial metabolic disorder associated with insulin resistance plays significant roles in the development of atherosclerosis in MetS. On the other hand, little is known about the clinical features and significance of postprandial hemodynamic condition in MetS. Tamminen et al. [6] demonstrated impaired changes in central BP under normoglycemic–hyperinsulinemic conditions in type 2 diabetes mellitus (T2DM). In addition, marked resistance of the ability of insulin to decrease central BP and arterial stiffness was demonstrated in obese subjects [7]. Thus, accumulative evidence suggests changes in hemodynamic conditions associated with insulin and disturbance with insulin resistance. However, these results are based on hemodynamic changes under normoglycemic–hyperinsulinemic conditions using the euglycemic insulin clamp technique, i.e., artificial conditions. A recent manuscript by Ahuja et al. [8] demonstrated that central hemodynamic measures are more sensitive to the feeding state than standard brachial BP measurements, however, clinical factors or pathophysiological condition which influence postprandial hemodynamic variables are still in question. The aim of this study was to investigate the relationship between postprandial changes in hemodynamic variables after a mixed meal (Calorie Mate 500 kCal) and metabolic indicators related to MetS.

Section snippets

Subjects

The study was performed using 107 consecutive subjects (mean age, 46 years; 71 men and 36 women) in 4 cooperating hospitals. Fifty-two subjects were receiving treatment for one or more coronary risk factors, such as hypertension, diabetes mellitus and hyperlipidemia, while 55 were healthy volunteers. Current smoking was identified in 33 subjects. Two subjects had a history of myocardial infarction and 13 subjects had angiography-proved angina pectoris. Exclusion criteria were patients with

Results

Table 1 shows the backgrounds of participants in both groups. There were significant differences in most metabolic and hemodynamic parameters between groups in the fasting state. Fasting rSBP2 was significantly higher in the MetS group whereas fasting AI showed no significant difference. Fasting and postprandial changes in brachial BP are shown in Fig. 1. Serial changes in systolic BP after meal loading showed no significant difference throughout the postprandial period in both groups (Fig. 1

Central arterial pressure as an independent predictor of cardiovascular disease

Central aortic BP, i.e., aortic or carotid arterial BP, is pathophysiologically more relevant than peripheral pressures for the pathogenesis of cardiovascular disease [13], and is an independent predictor of outcome in patients with renal failure [1] and in the large-scale ASCOT-CAFÉ study [2]. From a pathophysiological viewpoint, aortic and not brachial BP is “seen” by the heart and the coronary and carotid arteries, the 3 specific sites where main clinical events occur [1]. In addition,

Conclusion

To the best of our knowledge, this is the first investigation demonstrating the blunted response of postprandial central BP regulation in MetS using a mixed meal. Dysfunctional postprandial hemodynamic regulation after daily food intake is another feature of MetS that may contribute to the progression of cardiovascular disease.

Conflict of interest/disclosure

None.

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