Influence of Altitude Exposure on Coronary Flow Reserve

Wyss, Christophe; Koepfli, Pascal; Fretz, Gregory; Seebauer, Magdalena; Schirlo, Christian; Kaufmann, Philipp A.

doi:10.1161/01.cir.0000087432.63671.2e

Cited by 113 publications

(92 citation statements)

References 32 publications

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“…29 Nevertheless, coronary artery disease remains the main cause of sudden cardiac death 30 as a result of reduced coronary vasodilatory reserve and increased cardiac work. 31 However, patients asymptomatic after conventional treatment perfectly tolerate altitude exposure, 32,33 even 6 months after revascularization. 34 To date, no relation has been found between acute mountain sickness (AMS), high-altitude pulmonary (HAPE) or cerebral (HACE) edema, and alteration in cardiac function.…”

Section: Clinical Perspective On P 794mentioning

confidence: 99%

Electrocardiographic Changes During Exercise in Acute Hypoxia and Susceptibility to Severe High-Altitude Illnesses

et al. 2015

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Background-The goals of this study were to compare ECG at moderate exercise in normoxia and hypoxia at the same heart rate, to provide evidence of independent predictors of hypoxia-induced ECG changes, and to evaluate ECG risk factors of severe high-altitude illness. Methods and Results-A total of 456 subjects performed a 20-minute hypoxia exercise test with continuous recording of ECG and physiological measurements before a sojourn above 4000 m. Hypoxia did not induce any conduction disorder, arrhythmias, or change in QRS axis. The amplitude of the P wave in V 1 was lower in hypoxia than in normoxia. The amplitudes of the R, S, and T waves and the Sokolow index decreased in hypoxia. Under hypoxia, the amplitude of the ST segment decreased in II and V 6 and increased in V 1 , the ST slope rose in V 5 and V 6 , and the J point was lower in II, V 5 , and V 6 . Multivariate regression of hypoxic/normoxic ratios of electrophysiological parameters and clinical characteristics showed a correlation between the decrease in Sokolow index and T-wave amplitude in V 5 with desaturation at exercise. Trained status and low body mass index were associated with a smaller decrease in T-wave amplitude in V 5 and V 6 .Comparison of ECG between subjects suffering or not suffering from severe high-altitude illness failed to show any difference. Conclusions-During

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Section: Clinical Perspective On P 794mentioning

confidence: 99%

Electrocardiographic Changes During Exercise in Acute Hypoxia and Susceptibility to Severe High-Altitude Illnesses

et al. 2015

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“…Under baseline conditions, MBF was measured both at rest and during intravenous administration of adenosine (140 g ⅐ kg Ϫ1 ⅐ min Ϫ1 ), as previously reported (14,28). Arterial blood pressure was recorded by an automatic cuff sphygmomanometer at 1-min intervals, and the ECG was monitored continuously throughout the procedure.…”

Section: Study Populationmentioning

confidence: 99%

Systemic nitric oxide synthase inhibition improves coronary flow reserve to adenosine in patients with significant stenoses

Kaufmann

Rimoldi

Gnecchi‐Ruscone

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Kaufmann PA, Rimoldi OE, Gnecchi-Ruscone T, Luscher TF, Camici PG. Systemic nitric oxide synthase inhibition improves coronary flow reserve to adenosine in patients with significant stenoses. Am J Physiol Heart Circ Physiol 293: H2178-H2182, 2007. First published July 27, 2007; doi:10.1152/ajpheart.01292.2006.-We studied the impact of systemic infusion of the nitric oxide synthase (NOS) inhibitor N G -monomethyl-L-arginine (L-NMMA) on coronary flow reserve (CFR) in patients with coronary artery disease (CAD). We have previously demonstrated that CFR to adenosine was significantly increased after systemic infusion of L-NMMA in normal volunteers but not in recently transplanted denervated hearts. At baseline, myocardial blood flow (MBF; ml ⅐ min Ϫ1 ⅐ g Ϫ1 ) was measured at rest and during intravenous administration of adenosine (140 g ⅐ kg Ϫ1 ⅐ min Ϫ1 ) in 10 controls (47 Ϯ 5 yr) and 10 CAD patients (58 Ϯ 8 yr; P Ͻ 0.01 vs. controls) using positron emission tomography and 15 O-labeled water. Both MBF measurements were repeated during intravenous infusion of 10 mg/kg L-NMMA. CFR was calculated as the ratio of MBF during adenosine to MBF at rest. CFR was significantly higher in healthy volunteers than in CAD patients and increased significantly after L-NMMA in controls (4.00 Ϯ 1.10 to 6.15 Ϯ 1.35; P Ͻ 0.0001) and in patients, both in territories subtended by stenotic coronary arteries (Ͼ70% luminal diameter; 2.06 Ϯ 1.13 to 3.21 Ϯ 1.07; P Ͻ 0.01) and in remote segments (3.20 Ϯ 1.23 to 3.92 Ϯ 1.62; P Ͻ 0.05). In conclusion, CFR can be significantly increased in CAD by a systemic infusion of L-NMMA. Similarly to our previous findings in normal volunteers, this suggests that adenosine-induced hyperemia in CAD patients is constrained by a mechanism that can be relieved by systemic NOS inhibition with L-NMMA. coronary circulation; autonomic nervous system; ischemic heart disease; cardiac imaging; positron emission tomography IT IS WELL ESTABLISHED THAT myocardial ischemia is a powerful stimulus for vasodilatation of coronary resistive vessels. The vasodilator response is reported to be near maximal for ischemic times of up to 15-20 s, while no further changes are observed for longer ischemic times (16).Experimental studies in animals have proven that intracoronary or intravenous infusion of adenosine achieves a degree of coronary vasodilatation comparable to that obtained after a period of ischemia of 15-20 s. In normal humans, intravenous infusion of 140 g/kg adenosine produces an increase in myocardial blood flow (MBF) approximately fourfold above the resting value with no further increase at higher adenosine doses (12,29).In a recent study in normal volunteers (15), we demonstrated that hyperemic MBF measured during the combined intravenous infusion of adenosine (140 g/kg) and the nitric oxide synthase (NOS) inhibitor N G -monomethyl-L-arginine (L-NMMA; 10 mg/ kg) was 53% higher than that during infusion of adenosine alone. This effect seems to necessitate an intact cardiac innervation, since no increase in MBF during ...

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“…The latter induced MBF responses comparing well with those reported for bicycle exercise in healthy volunteers 6 and in CAD patients. 7 In myocardial segments subtended by a significant coronary stenosis, there was progressive blunting of regional MBF with both agents. Surprisingly, however, dobutamine achieved greater hyperemia.…”

Section: See Related Article P 324mentioning

confidence: 96%

Differential effects of pharmacologic stressors: More than meets the eye

Kaufmann

2006

Journal of Nuclear Cardiology

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Influence of Altitude Exposure on Coronary Flow Reserve

Cited by 113 publications

References 32 publications

Electrocardiographic Changes During Exercise in Acute Hypoxia and Susceptibility to Severe High-Altitude Illnesses

Electrocardiographic Changes During Exercise in Acute Hypoxia and Susceptibility to Severe High-Altitude Illnesses

Systemic nitric oxide synthase inhibition improves coronary flow reserve to adenosine in patients with significant stenoses

Differential effects of pharmacologic stressors: More than meets the eye

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