Heart mechanics at high altitude: 6 days on the top of Europe

Maufrais, Claire; Rupp, Thomas; Bouzat, Pierre; Doucende, Grégory; Vergès, Samuel; Nottin, Stéphane; Walther, Guillaume

doi:10.1093/ehjci/jew286

Cited by 43 publications

(83 citation statements)

References 28 publications

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“…The LV CS, rotations and twist were obtained from short‐axis views according to specific recommendations (vanDalen, Vletter, Soliman, ten Cate, & Geleijnse, ). Analysis of LV strains and twist were conducted as previously described (Maufrais et al., , ; Nottin et al., ). Moreover, Echopac software includes an automatic detection of the subendocardial and subepicardial layers, allowing the assessment of the GLS and CS of the different layers.…”

Section: Methodsmentioning

confidence: 99%

“…The percentage of untwist during isovolumic relaxation time (IVRT; %UT IVRT ) was calculated as follows (Zhang, Zhou, Pu, Zou, & Tan, ): %UT IVRT = [(twist at aortic valve closure − twist at the end of IVRT)/twist at aortic valve closure] × 100. The untwisting efficiency estimated through the untwisting rate/peak twist ratio as previously described was calculated as the peak untwisting velocity normalized for peak twist (Maufrais et al., ; Notomi et al., ). The TSR was calculated as peak twist divided by mean CS averaged from the basal and apical levels.…”

Section: Methodsmentioning

confidence: 99%

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Medex 2015: The key role of cardiac mechanics to maintain biventricular function at high altitude

Maufrais

Rupp

Bouzat

et al. 2019

Experimental Physiology

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New Findings What is the central question of this study?This study is the first to investigate the effects of high‐altitude trekking on biventricular mechanics, including measurements of left ventricular subendocardial and subepicardial function. What is the main finding and its importance?We provide new evidence that an increased contractility and untwisting efficiency, a key element of diastolic function, probably plays a key role in preservation of cardiac function during high‐altitude trekking. Persistent increased loading conditions during several weeks at high altitude might have a key role in the appearance of left or right ventricular dysfunction. Abstract Cardiac responses to acute hypoxic exposure have been thoroughly investigated. We analysed the effects of high‐altitude trekking (i.e. prolonged hypoxic exposure) on biventricular function, including the evaluation of subendocardial and subepicardial function in the left ventricle (LV). Resting evaluations of LV and right ventricular (RV) function and mechanics were assessed by speckle tracking echocardiography on 20 subjects at sea level and at high altitude (5085 m, after a 10 day ascent). Pulmonary artery systolic pressure was increased at high altitude (sea level, 13.1 ± 5.9 mmHg; high altitude, 26.6 ± 10.8 mmHg; P < 0.001). Left ventricular volumes were decreased, whereas RV volumes were increased at high altitude. Alterations in pulmonary artery systolic pressure and cardiac volumes were correlated with hypoxaemia. We observed neither RV nor LV systolic dysfunction, including analysis of LV subendocardial and subepicardial function. Left ventricular systolic strain rates were enhanced at high altitude. Transmitral and transtricuspid diastolic filling ratios were decreased at high altitude. Diastolic apical rotational rate, untwisting rate and untwisting rate/peak twist ratio (i.e. untwisting efficiency) were enhanced at high altitude. We observed no echocardiographic signs of LV and RV pathological dysfunction at rest at high altitude. In contrast, our data highlighted major changes in the LV mechanics, with an increased LV contractility and a higher untwisting efficiency at high altitude. Biventricular interaction, alterations in loading conditions and an increase in plasma catecholamine concentration might partly explain these modifications. Thus, we demonstrated that LV mechanics (i.e. increased strain rates and untwisting efficiency) have a key role in preservation of cardiac function during high‐altitude trekking.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Medex 2015: The key role of cardiac mechanics to maintain biventricular function at high altitude

Maufrais

Rupp

Bouzat

et al. 2019

Experimental Physiology

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“…Previously, it was considered that a reduction in plasma volume or a direct effect of hypoxia on LV myocardial contractility were probably responsible [ 4 ]. More recently it has been suggested that increased RV afterload may be of greater importance [ 5 ].…”

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confidence: 99%

“…Right ventricular systolic pressure (RVSP) was estimated from the peak velocity of the tricuspid regurgitation jet [ 1 , 5 , 7 – 9 ]. The LV and RV indices of myocardial performance (LIMP and RIMP) and tricuspid annular planar systolic excursion (TAPSE) were measured.…”

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confidence: 99%

Iron bioavailability and cardiopulmonary function during ascent to very high altitude

et al. 2020

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More than one hundred million people reside worldwide at altitudes in excess of 2500 m above sea level. In the millions more who sojourn at high altitude for recreational, occupational or military pursuits, hypobaric hypoxia drives physiological changes affecting the pulmonary circulation, haematocrit and right ventricle (RV) [1]. Coincident with these, maximal left ventricular (LV) stroke volume (SV) falls [2], with a reduction of 20% reported after a 2-week stay at 4300 m [3]. A rise in heart rate (HR) compensates at rest and during submaximal exercise but is insufficient during maximal intensity exercise, constraining maximal cardiac output (CO). Previously, it was considered that a reduction in plasma volume or a direct effect of hypoxia on LV myocardial contractility were probably responsible [4]. More recently it has been suggested that increased RV afterload may be of greater importance [5].

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“…It has been well documented that the global systolic left ventricular (LV) and right ventricular (RV) functions are well preserved, but both ventricles show altered filling patterns, subendocardial systolic dysfunction, and the increase in mean pulmonary arterial pressure (mPAP) [1][2][3]. Notably, there may be a potential association between altered cardiac functions and the incidence of acute mountain sickness [4], whereas the increase in mPAP may limit exercise capacity at HA [5,6]. Although the cardiac responses to HA exposure are of great significance, the detailed characterizations are largely unknown.…”

Section: Introductionmentioning

confidence: 99%

Effects of baseline heart rate at sea level on cardiac responses to high-altitude exposure

Tian

Liu

Yang

et al. 2020

Int J Cardiovasc Imaging

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High-altitude (HA) exposure has been widely considered as a cardiac stress, and associated with altered cardiac function. However, the characteristics of cardiac responses to HA exposure are unclear. In total, 240 healthy men were enrolled and ascended to 4100 m by bus within 7 days. Standard echocardiography and color tissue Doppler imaging were performed at sea level and at 4100 m. In all subjects, HA exposure increased HR [65 (59, 71) vs. 72 (63, 80) beats/min, p < 0.001] but decreased the stroke volume index (SVi) [35.5 (30.5, 42.3) vs. 32.9 (27.4, 39.5) ml/m 2 , p < 0.001], leading to an unchanged cardiac index (CI). Moreover, baseline HR was negatively correlated with HA exposure-induced changes in HR (r = − 0.410, p < 0.001) and CI (r = − 0.314, p < 0.001). Following HA exposure, subjects with lowest tertile of baseline HR showed an increased HR [56 (53, 58) vs. 65 (58, 73) beats/min, p < 0.001], left ventricular ejection fraction (LVEF) [61.7 (56.5, 68.0) vs. 66.1 (60.7, 71.5) %, p = 0.004] and mitral S′ velocity [5.8 ± 1.4 vs. 6.5 ± 1.9 cm/s, p = 0.040]. However, subjects with highest tertile of baseline HR showed an unchanged HR, LVEF and mitral S′ velocity, but a decreased E′ velocity [9.2 ± 2.0 vs. 8.4 ± 1.8 cm/s, p = 0.003]. Our findings indicate that baseline HR at sea level could determine cardiac responses to HA exposure; these responses were characterized by enhanced LV function in subjects with a low baseline HR and by reduced LV myocardial velocity in early diastole in subjects with a high baseline HR.

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Heart mechanics at high altitude: 6 days on the top of Europe

Cited by 43 publications

References 28 publications

Medex 2015: The key role of cardiac mechanics to maintain biventricular function at high altitude

Medex 2015: The key role of cardiac mechanics to maintain biventricular function at high altitude

Iron bioavailability and cardiopulmonary function during ascent to very high altitude

Effects of baseline heart rate at sea level on cardiac responses to high-altitude exposure

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