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Alain Nitenberg

Publications and source records attributed to Alain Nitenberg.

14 recordsLinked to original sources
PubMed2006

Impaired coronary endothelium-dependent vasodilation is associated with microalbuminuria in patients with type 2 diabetes and angiographically normal coronary arteries.

OBJECTIVE: Microalbuminuria and impaired endothelium-dependent vasodilation are both predictors for cardiac events in patients with type 2 diabetes. The aim of the study was to evaluate whether microalbuminuria correlated with coronary endothelium-dependent vasodilation. RESEARCH DESIGN AND METHODS: We evaluated 84 patients (47 men, mean age 50.5 +/- 5.9 years) with type 2 diabetes for 9.4 +/- 3.4 years, without angiographic coronary stenosis and without major cardiovascular risk factors or other confounding factors, for endothelium investigation. Quantitative coronary angiography was used to assess coronary artery response to cold pressor testing, used to assess endothelium-dependent vasodilation, and to isosorbide dinitrate (endothelium-independent vasodilation). RESULTS: Endothelium-dependent vasodilation differed in the patients with and without microalbuminuria (changes in coronary artery diameter during cold pressor testing: -15.0 +/- 1.9% vs. -10.2 +/- 1.3%, respectively, P < 0.05) and correlated with urinary albumin excretion rate (r = -0.39, P = 0.003), diastolic blood pressure (r = 0.29, P < 0.01), and left ventricular mass index (r = -0.24, P < 0.05). Independent predictors for endothelium-dependent vasodilation were urinary albumin excretion rate (beta -0.04 [95% CI -0.07 to -0.01], P < 0.005) and left ventricular mass index (-0.26 [-0.49 to -0.05], P < 0.05). Endothelium-independent vasodilation was similar in both groups. CONCLUSIONS: Type 2 diabetic patients with microalbuminuria have a more severely impaired coronary endothelium-dependent vasodilation than those with normoalbuminuria. These data suggest a common pathophysiological process for both coronary vasomotor abnormalities and microalbuminuria.

Albuminuria↗
PubMed2005

Mean aortic pressure is the geometric mean of systolic and diastolic aortic pressure in resting humans.

The aim of our study was twofold: 1) to establish a mathematical link between mean aortic pressure (MAP) and systolic (SAP) and diastolic aortic pressures (DAP) by testing the hypothesis that either the geometric mean or the harmonic mean of SAP and DAP were reliable MAP estimates; and 2) to critically evaluate three empirical formulas recently proposed to estimate MAP. High-fidelity pressures were recorded at rest at the aortic root level in controls (n = 31) and in subjects with various forms of cardiovascular diseases (n = 108). The time-averaged MAP and the pulse pressure (PP = SAP - DAP) were calculated. The MAP ranged from 66 to 160 mmHg [mean = 107.9 mmHg (SD 18.2)]. The geometric mean, i.e., the square root of the product of SAP and DAP, furnished a reliable estimate of MAP [mean bias = 0.3 mmHg (SD 2.7)]. The harmonic mean was inaccurate. The following MAP formulas were also tested: DAP + 0.412 PP (Meaney E, Alva F, Meaney A, Alva J, and Webel R. Heart 84: 64, 2000), DAP + 0.33 PP + 5 mmHg [Chemla D, Hébert JL, Aptecar E, Mazoit JX, Zamani K, Frank R, Fontaine G, Nitenberg A, and Lecarpentier Y. Clin Sci (Lond) 103: 7-13, 2002], and DAP + [0.33 + (heart rate x 0.0012)] PP (Razminia M, Trivedi A, Molnar J, Elbzour M, Guerrero M, Salem Y, Ahmed A, Khosla S, Lubell DL. Catheter Cardiovasc Interv 63: 419-425, 2004). They all provided accurate and precise estimates of MAP [mean bias = -0.2 (SD 2.9), -0.3 (SD 2.7), and 0.1 mmHg (SD 2.9), respectively]. The implications of the geometric mean pressure strictly pertained to the central (not peripheral) level. It was demonstrated that the fractional systolic (SAP/MAP) and diastolic (DAP/MAP) pressures were reciprocal estimates of aortic pulsatility and that the SAP times DAP product matched the total peripheral resistance times cardiac power product. In conclusion, although the previously described thumb-rules applied, the "geometric MAP" appears more valuable as it established a simple mathematical link between the steady and pulsatile component of aortic pressure.

Adult↗
PubMed2005

Cardiovascular outcome of patients with abnormal coronary vasomotion and normal coronary arteriography is worse in type 2 diabetes mellitus than in arterial hypertension: a 10 year follow-up study.

Diabetes and arterial hypertension are major cardiovascular risk factors. Coronary endothelial dysfunction is frequently observed in diabetic and hypertensive patients. This study was designed to compare cardiovascular outcome of hypertensive (HT) and type 2 diabetic patients (D2) with angiographically normal coronary arteries on the basis of their epicardial coronary endothelial function. Coronary reactivity assessment by cold-pressor test (CPT) using quantitative coronary angiography was achieved in 65 HT (45 males, 20 females) aged 51.9+/-7.6 years, and in 59 D2 (32 males, 27 females) aged 48.9+/-7.3 years, with angiographically normal coronary arteries and without other major coronary risk factor. Cardiovascular events (CVE) were recorded with a mean follow-up of 108+/-15 months in HT, and 113+/-10 months in D2. During CPT, in HT coronary artery dilation occurred in 10.8% of the patients, no change in 21.5%, and constriction in 67.7%. In D2, dilation occurred in 3.4% of the patients, no change in 18.6%, and constriction in 78.0%. During follow-up, in HT there were nine CVE in 6/65 patients (9.2%), all in the 6/44 (13.6%) patients with coronary artery constriction. In D2, there were 18 CVE in 16/59 patients (27.1%, P<0.01 versus HT), with 17 CVE in the 15/46 patients with coronary artery constriction, and one CVE in the 1/13 patients without constriction (32.6% versus 7.7%). In patients with coronary artery constriction, CVE were more frequent in D2 than in HT (P<0.05). Last, CVE were more severe and occurred earlier in D2 than in HT. In conclusion, epicardial coronary endothelial dysfunction is predictive of long-term CVE in HT and D2 with angiographically normal coronary arteries. Cardiovascular outcome of patients with coronary constriction is worse in D2 than in HT. At the opposite, patients without constriction have good cardiovascular prognosis in both subgroups.

Adult↗
PubMed2004

Epicardial coronary artery constriction to cold pressor test is predictive of cardiovascular events in hypertensive patients with angiographically normal coronary arteries and without other major coronary risk factor.

Epicardial coronary endothelial dysfunction independently predicts cardiovascular events in patients with coronary risk factors. This study was designed to evaluate outcome of hypertensive patients on the basis of their epicardial coronary function assessed by cold pressor test (CPT). Control subjects (n = 68, 48.8 +/- 7.6 years) and hypertensive patients (n = 83, 51.3 +/- 7.9 years) with angiographically normal coronary arteries and without other major coronary risk factor underwent epicardial coronary reactivity assessment to CPT using quantitative angiography. Cardiovascular events were recorded with a mean follow-up of 115 months (range 84-132). In control subjects, dilation occurred in 88.2%, no change in 11.8% (mean diameter change: +14.6 +/- 9.3%). In hypertensive patients, dilation occurred in 13.3%, no change in 25.3% (mean diameter change for both: +10.9 +/- 11.2%), and constriction in 61.4% (mean diameter change: -12.7 +/- 3.4%). Endothelium-independent dilation was normal in control subjects and hypertensive patients. In control subjects, there were three cardiovascular events in two subjects (2.9%). In hypertensive patients, there were 17 cardiovascular events in 12 patients (14.5%, P < 0.01 versus control subjects), with 15 cardiovascular events in the 10/51 patients (19.6%) with coronary artery constriction, and two cardiovascular events in the 2/32 patients (6.3%) with no change or dilation (P < 0.05). In conclusion, in hypertensive patients with angiographically normal coronary arteries and without other major coronary risk factors, epicardial coronary artery dysfunction assessed by the cold pressor test is predictive of long-term cardiovascular events.

Adult↗
PubMed2004

Prognostic value of epicardial coronary artery constriction to the cold pressor test in type 2 diabetic patients with angiographically normal coronary arteries and no other major coronary risk factors.

OBJECTIVE: Endothelium-dependent coronary dilation is impaired in diabetic patients and has been found to independently predict cardiovascular events (CVEs) in patients with multiple coronary risk factors. The aim of this study was to evaluate the outcome of type 2 diabetic patients on the basis of epicardial coronary dysfunction. RESEARCH DESIGN AND METHODS: We examined 56 control subjects (aged 51.7 +/- 6.4 years) using coronary artery response to the cold pressor test (quantitative coronary angiography) and compared them with 72 type 2 diabetic patients (aged 50.3 +/- 8.5 years) without other major coronary risk factors. RESULTS: Average diameter change was 17.2 +/- 10.4% in the control subjects, dilation occurred in 91.1% of subjects, no change occurred in 8.9%, and there was no constriction. Average diameter change was -14.4 +/- 12.1% in diabetic patients (P < 0.001 vs. control subjects), constriction occurred in 73.6%, no change occurred in 26.4%, and there was no dilation. CVEs were recorded with a mean follow-up of 45 +/- 19 months. There was 1 CVE in the control group and 26 CVEs in 18 of 72 diabetic patients (P < 0.001 vs. control subjects), with 23 events in 16 of 53 diabetic patients with coronary artery constriction (P < 0.001 vs. control subjects), and 3 events in 2 of 19 diabetic patients with no diameter change (NS vs. control subjects). CONCLUSIONS: In type 2 diabetic patients without other major coronary risk factors, constriction of angiographically normal coronary arteries to the cold pressor test is predictive of long-term CVEs.

Age of Onset↗
PubMed2003

Contribution of systemic vascular resistance and total arterial compliance to effective arterial elastance in humans.

The respective contribution of systemic vascular resistance (R) and total arterial compliance (C) to the arterial load remains to be established in humans. Effective arterial elastance (Ea), i.e., the left ventricular end-systolic pressure (LVESP)-over-stroke volume ratio, is a reliable estimate of arterial load. It is widely accepted that Ea mainly relates to mean aortic pressure (MAP) and thus to the R-to-T ratio (R/T ratio), where T is cycle length. We tested the contribution of R/T and 1/C to Ea in 20 normotensive and 46 hypertensive subjects (MAP range: 84-160 mmHg). The multilinear model applied (Ea = 1.00R/T + 0.42/C - 0.04; r2 = 0.97). The sensitivity of Ea to a change in R/T was 2.5 times higher than to a similar change in 1/C in both normotensive and hypertensive adults. The LVESP was more strongly related to systolic aortic pressure (SAP; r2 = 0.94) than to MAP (r2 = 0.83), and LVESP matched 90% SAP (bias = 0 +/- 5mmHg). An alternative model of Ea is proposed, in which Ea is proportional to the heart rate x SAP product-over-cardiac index ratio whatever the MAP.

Aorta↗
PubMed2003

Should flow-volume loop be monitored in sleep apnea patients treated with continuous positive airway pressure?

Nasal continuous positive airway pressure (nCPAP) has been widely established in the treatment of obstructive sleep apnea syndrome (OSAS). However, only few studies have evaluated long-term effects of this treatment on lung function. This study assesses the effect of nCPAP on lung function parameters and response to bronchodilators in 50 OSAS patients. Spirometry and arterial blood gas measurements were performed before starting nCPAP and after 16.8 +/- 8 months of treatment. Of the 50 study patients (55 +/- 12 years, with an apnea/hypopnea index of 47 +/- 34h(-1)), 15 had asthma, 13 had chronic obstructive pulmonary disease (COPD) and 22 had no obstructive airway disease (NOAD). In the entire population, significant decreases in FEF50 (from 69 +/- 38% to 61 +/- 30%, P < 0.005), FEF25 (from 53 +/- 34% to 46 +/- 28%, P < 0.05) and FEF25-75 (from 65 +/- 33% to 57 +/- 27%, P < 0.005) were observed after treatment. No impairment of lung function was found in COPD and asthmatic patients. In contrast, lung function was changed in the NOAD group where FEF50, FEF25 and FEF25-75 as well as FEV1 and FEV1/VC ratio were significantly reduced. Moreover, bronchial hyperresponsiveness occurred in five of 22 patients of this group. These results suggest that tolerance of nCPAP should be handled by long-term follow-up of flow-volume loops.

Adult↗
PubMed2002

Empirical estimates of mean aortic pressure: advantages, drawbacks and implications for pressure redundancy.

Mean arterial pressure (MAP) is estimated at the brachial artery level by adding a fraction of pulse pressure (form factor; =0.33) to diastolic pressure. We tested the hypothesis that a fixed form factor can also be used at the aortic root level. We recorded systolic aortic pressure (SAP) and diastolic aortic pressure (DAP), and we calculated aortic pulse pressure (PP) and the time-averaged MAP in the aorta of resting adults (n=73; age 43+/-14 years). Wave reflection was quantified using the augmentation index. The aortic form factor (range 0.35-0.53) decreased with age, MAP, PP and augmentation index (each P<0.001). The mean form factor value (0.45) gave a reasonable estimation of MAP (MAP=DAP+0.45PP; bias=0+/-2 mmHg), and the bias increased with MAP (P<0.001). An alternative formula (MAP=DAP+PP/3+5 mmHg) gave a more precise estimation (bias=0+/-1 mmHg), and the bias was not related to MAP. This latter formula was consistent with the previously reported mean pulse wave amplification of 15 mmHg, and with unchanged MAP and diastolic pressure from aorta to periphery. Multiple linear regression showed that 99% of the variability of MAP was explained by the combined influence of DAP and SAP, thus confirming major pressure redundancy. Results were obtained irrespective of whether the marked differences in heart period and extent of wave reflection between subjects were taken into account. In conclusion, the aortic form factor was strongly influenced by age, aortic pressure and wave reflection. An empirical formula (MAP=DAP+PP/3+5 mmHg) that is consistent with mechanical principles in the arterial system gave a more precise estimate of MAP in the aorta of resting humans. Only two distinct pressure-powered functions were carried out in the (SAP, DAP, MAP, PP) four-pressure set.

Adult↗
PubMed2002

Coronary microvascular adaptation to myocardial metabolic demand can be restored by inhibition of iron-catalyzed formation of oxygen free radicals in type 2 diabetic patients.

Dilation of coronary vessels is impaired in diabetic patients when myocardial metabolic demand is increased. Deferoxamine (DFX) restores a normal dilation of epicardial coronary arteries. To assess the effects of DFX on metabolic coronary microvascular dilation in type 2 diabetic patients, coronary blood flow was measured using intracoronary Doppler and quantitative angiography in 17 type 2 diabetic patients with normal coronary arteries and without any other coronary risk factors. Measurements were made at baseline and during a cold pressor test (CPT), before and after intravenous administration of DFX. With a similar rate-pressure product (RPP) increase during CPT before and after DFX (+21.1 +/- 8.7 vs. +20.5 +/- 8.9%, respectively), coronary blood flow increase was significantly enhanced after DFX (+31.8 +/- 16.7 vs. +6.3 +/- 12.9% before DFX, P < 0.001). Moreover, coronary resistance increased during CPT before DFX and decreased after DFX (+14.8 +/- 21.9 vs. -7.9 +/- 10.9%, respectively, P < 0.001). Lastly, the negative relationship between coronary blood flow and RPP before DFX (R = 0.546, P < 0.05) was changed in a positive relationship after DFX (R = 0.518, P < 0.05). In conclusion, in type 2 diabetic patients, inhibition of iron-catalyzed oxidative reactions by DFX restored dilation of the coronary microcirculation and a normal matching between myocardial metabolic demand and coronary blood flow.

Blood Flow Velocity↗