Effects of altitude on exercise level and heart rate in patients with coronary artery disease and healthy controls

Background. To evaluate the safety and effects of high altitude on exercise level and heart rate in patients with coronary artery disease compared with healthy controls. Methods. Eight patients with a history of an acute myocardial infarction (ejection fraction >5%) with a low-risk score were compared with seven healthy subjects during the Dutch Heart Expedition at the Aconcagua in Argentina in March 2007. All subjects underwent a maximum exercise test with a cycle ergometer at sea level and base camp, after ten days of acclimatisation, at an altitude of 4200 m. Exercise capacity and maximum heart rate were compared between groups and within subjects. Results. There was a significant decrease in maximum heart rate at high altitude compared with sea level in both the patient and the control group (166 vs. 139 beats/min, p<0.001 and 181 vs. 150 beats/min, p<0.001). There was no significant difference in the decrease of the exercise level and maximum heart rate between patients and healthy controls (-31 vs. -30%, p=0.673). Conclusion. Both patients and healthy controls showed a similar decrease in exercise capacity and maximum heart rate at 4200 m compared with sea level, suggesting that patients with a history of coronary artery disease may tolerate stay and exercise at high altitude similarly to healthy controls. (Neth Heart J 2010;18:118-21.)     

Exercise hyperpnea in chronic heart failure: relationships to lung stiffness and expiratory flow limitation.

The changes in breathing pattern and lung mechanics in response to incremental exercise were compared in 14 subjects with chronic heart failure and 15 normal subjects. In chronic heart failure subjects, exercise hyperpnea was achieved by increasing breathing frequency more than tidal volume. The rate of increase in breathing frequency with carbon dioxide output was inversely correlated (r = -0.61, P < 0.05) with dynamic lung compliance measured at rest, but not with static lung compliance either at rest or at maximum exercise. Although decrease in expiratory flow reserve near functional residual capacity in chronic heart failure occurred earlier with exercise than in the normal subjects (P < 0.01), it was not correlated with changes in breathing pattern or occurrence of tachypnea. Tachypnea was achieved in chronic heart failure subjects with an increase in duty cycle because of a greater than normal decrease in expiratory time with exercise. We conclude that in chronic heart failure preexisting increase in lung stiffness plays a significant role in causing tachypnea during exercise. The results of the present study do not support the hypothesis that dynamic compression of the airways downstream from the flow-limiting segment occurring during exercise contributes to hyperpnea.     

Dependence of the functional capacity of the cardiorespiratory system on the body mass in patients with coronary heart disease

The influence of excessive body mass on the development of cardiorespiratory deficiency was studied in patients with coronary heart disease (CHD). Basic parameters of hemodynamics and gas exchange were measured during a graded exercise test. In the CHD patients with excessive body mass, mean blood pressure, cardiac output, left ventricular power output, and left ventricular posterior wall thickness were significantly increased even at rest. During exercise, these patients displayed an increase in myocardial energy consumption and peripheral vascular resistance. It was concluded that an excess in body mass is critical when the increase in the body mass index (Quetelet’s index) exceeds the norm by 20%.     

Near-maximal fractional oxygen extraction by active skeletal muscle in patients with chronic heart failure.

Systemic oxygen uptake and deep femoral vein oxygen content were determined at peak exercise in 53 patients with chronic heart failure with impaired systolic function (mean left ventricular ejection fraction 0.18; n = 41) or preserved systolic function (mean left ventricular ejection fraction 0.70; n = 12) and in 6 age-matched sedentary normal subjects. At peak exercise, deep femoral vein oxygen content in heart failure patients with impaired systolic function and preserved systolic function were similar, both significantly lower than that of normal subjects (2.5 +/- 0.1, 2.9 +/- 0.2, and 5.0 +/- 0.1 ml/100 ml, respectively; P < 0.05). Deep femoral venous oxygen content was lower in patients with the greater impairment of aerobic capacity, regardless of the underlying systolic function (r = 0.72, P < 0.01). Fractional oxygen extraction in the skeletal muscle at peak exercise is enhanced in patients with chronic heart failure when compared with normal subjects, in proportion to the degree of aerobic impairment.     

Metabolic Adaptations May Counteract Ventilatory Adaptations of Intermittent Hypoxic Exposure during Submaximal Exercise at Altitudes up to 4000 m

Intermittent hypoxic exposure (IHE) has been shown to induce aspects of altitude acclimatization which affect ventilatory, cardiovascular and metabolic responses during exercise in normoxia and hypoxia. However, knowledge on altitude-dependent effects and possible interactions remains scarce. Therefore, we determined the effects of IHE on cardiorespiratory and metabolic responses at different simulated altitudes in the same healthy subjects. Eight healthy male volunteers participated in the study and were tested before and 1 to 2 days after IHE (7×1 hour at 4500 m). The participants cycled at 2 submaximal workloads (corresponding to 40% and 60% of peak oxygen uptake at low altitude) at simulated altitudes of 2000 m, 3000 m, and 4000 m in a randomized order. Gas analysis was performed and arterial oxygen saturation, blood lactate concentrations, and blood gases were determined during exercise. Additionally baroreflex sensitivity, hypoxic and hypercapnic ventilatory response were determined before and after IHE. Hypoxic ventilatory response was increased after IHE (p<0.05). There were no altitude-dependent changes by IHE in any of the determined parameters. However, blood lactate concentrations and carbon dioxide output were reduced; minute ventilation and arterial oxygen saturation were unchanged, and ventilatory equivalent for carbon dioxide was increased after IHE irrespective of altitude. Changes in hypoxic ventilatory response were associated with changes in blood lactate (r = −0.72, p<0.05). Changes in blood lactate correlated with changes in carbon dioxide output (r = 0.61, p<0.01) and minute ventilation (r = 0.54, p<0.01). Based on the present results it seems that the reductions in blood lactate and carbon dioxide output have counteracted the increased hypoxic ventilatory response. As a result minute ventilation and arterial oxygen saturation did not increase during submaximal exercise at simulated altitudes between 2000 m and 4000 m.     

Relationships of Oxygen Consumption, Hemodynamics, and Heart Rate Variability with the Functional Class of Coronary Artery Disease Patients

The functional classes (FCs) established according to the criteria of the New York Heart Association were tested for association with oxygen consumption, the state of central hemodynamics, and heart rate (HR) variability in coronary artery disease (CAD) patients. Oxygen consumption, central hemodynamics, and HR variability at rest and during exercise were assayed in 146 CAD patients and 30 healthy individuals (the control group). It was established that the peak oxygen consumption (VO_2max), anaerobic threshold, pulmonary ventilation, systolic and minute blood volume at the threshold load (TL), and HR variability in a supine position significantly decrease and the total vascular peripheral resistance at rest and during exercise increases with increasing FC in CAD patients. The closest correlation of FC was revealed with physical working capacity, anaerobic threshold, age, and peak oxygen consumption. Moderate correlations were established with the chronotropic function of the heart at the threshold load, HR variability, the high- and low-frequency components of the cardiac rhythm at TL, pulmonary ventilation, stroke volume at rest and at TL, and the carbon dioxide ventilation equivalent at TL. In healthy individuals, the peak oxygen consumption closely correlated with the HR variability, the very low frequency component at TL, and physical capacity. With an increase in FC in CAD patients, peak oxygen consumption became more tightly associated with the chronotropic function and the hemodynamic components at TL than with the HR variability in a supine position or at TL.     

应用心肺运动试验评估食管癌患者长期新辅助化疗前后整体功能的改变*

目的: 用心肺运动试验（CPET）定量评估化疗对人体整体心肺功能状态的影响。方法: 本研究选取2006年至2007年在MD Anderson癌症中心进行外科手术前化疗的6例食管癌患者。对该6例患者分别行化疗前后最大症状限制性CPET的客观定量评估。结果: ①新辅助化疗前后CPET核心指标的变化：显著降低的核心指标有峰值摄氧量（Peak VO₂）（P<0.05）,无氧阈（AT）、峰值氧脉搏（Peak VO₂/HR）、摄氧通气效率峰值平台（OUEP）（P<0.01）,核心指标显著上升的有VE/VCO₂最小值、VE-vs-VCO₂斜率（P<0.05）。2化疗前后CPET循环指标的变化：患者静息状态及热身状态的VO₂无明显变化,AT （P<0.01）及Peak VO₂ （P<0.05）均有下降。除静息及极限状态的下降不显著外,热身状态的摄氧通气效率（OUE）（P<0.05）及OUE@AT （P<0.01）呈现显著下降。四个状态的VE/ VCO₂均呈现上升趋势,但仅在热身状态的VE/ VCO₂ （P<0.05）及VE/ VCO₂@AT（P<0.01）有统计学意义。四个状态的VO₂ /HR均呈下降趋势,除VO₂/HR@AT（P<0.05）显著下降外,其他三个状态的变化尚无统计学差异。③化疗前后CPET通气指标的变化在整个运动过程中,除热身状态的PETCO₂（P<0.05）显著下降外,其余状态的PETCO₂呈现下降趋势,但尚无统计学差异。呼吸频率、每分通气量几乎无变化。患者四个状态的潮气量、VO₂/RF及VCO₂/RF均呈现下降趋势,但均无统计学差异。四个状态的PETO₂均呈现上升趋势,但无明显统计学差异。结论: 心肺运动试验可以从呼吸、循环、代谢等方面客观定量评估化疗前后机体功能状态的变化。     

Metabolic responses to light arm and leg exercise when sitting

Seven male subjects performed progressive exercises with a light work load on an upper limb or bicycle ergometer in the sitting position. At any comparable work load above zero, arm exercise induced higher oxygen uptake, ventilation, heart rate, oxygen pulse, respiratory rate and tidal volume than leg exercise. At similar levels of VO2 above 0.45 1 X min-1, heart rate and ventilation were higher during arm exercise. A close linear relationship between carbon dioxide output and oxygen uptake was observed during both arm and leg exercises, the slope for arm work being steeper. The ventilatory equivalent for VCO2 (VE/VCO2) gradually decreased during both types of exercise. The ventilatory equivalent for VO2(VE/VO2) remained constant (arm) while it rose (leg) to a peak at 9.8 W and then gradually decreased. Ventilation in relation to tidal volume had a linear relationship with leg exercise, but became curvilinear with arm exercise after tidal volume exceeded 1100 ml. The observed differences in response between arm and leg exercises at a given work load appear to be influenced by differences in sympathetic outflow due to the greater level of static contraction of the relatively small muscle groups required by arm exercise.     

左西孟旦联合沙库巴曲缬沙坦钠对慢性心衰患者血流动力学和运动能力的影响

摘要 目的：探讨左西孟旦联合沙库巴曲缬沙坦钠（诺欣妥）对慢性心衰患者血流动力学和运动能力的影响。方法：2018年1月至2019年5月选择在本院心内科诊治的慢性心衰患者80例,根据随机数字表法分为联合组50例,对照组30例。两组入院后均进行常规治疗,在此基础上,对照组给予沙库巴曲缬沙坦钠治疗,联合组给予沙库巴曲缬沙坦钠联合左西孟旦治疗,两组都治疗观察1个月,记录血流动力学和运动能力的变化情况。结果：治疗后联合组的总有效率显著高于对照组(98.0 % vs 80.0 %,P<0.05)。治疗后联合组的总有效率显著高于对照组(98.0 % vs 80.0 %,P<0.05)。两组治疗前(left ventricular ejection fraction,LVEF)值和(Left ventricular end-systolic diameter,LVSD)值比较无统计学意义(P>0.05),治疗1个月后,两组的的LVEF值显著高于治疗前,LVSD值显著低于治疗前(P<0.05),且上述指标的变化联合组更为显著(P<0.05)。两组治疗后的6 min步行距离都显著高于治疗前(P<0.05),且联合组也显著高于对照组(P<0.05)。结论：左西孟旦联合沙库巴曲缬沙坦钠治疗慢性心衰能改善患者的血流动力学状况和运动能力,从而提高治疗疗效。     

二尖瓣关闭不全患者的运动病理生理学特征的临床研究报告

目的:通过心肺运动试验(CPET)进行二尖瓣关闭不全的运动病理生理学特征的相关研究.方法:自2016年以来签署知情同意后,严格质控下完成规范化CPET极限运动的中重度二尖瓣关闭不全患者26例,取同期正常人11例为对照组.将CPET核心指标按照标准方法分析计算,并与正常人比较,进行组间统计学独立样本t检验.同时将患者是否...     

Suppression of cerebral hemodynamics is associated with reduced functional capacity in patients with heart failure

This investigation elucidated the underlying mechanisms of functional impairments in patients with heart failure (HF) by simultaneously comparing cardiac-cerebral-muscle hemodynamic and ventilatory responses to exercise among HF patients with various functional capacities. One hundred one patients with HF [New York Heart Association HF functional class II (HF-II, n = 53) and functional class III (HF-III, n = 48) patients] and 71 normal subjects [older control (O-C, n = 39) and younger control (Y-C, n = 32) adults] performed an incremental exercise test using a bicycle ergometer. A recently developed noninvasive bioreactance device was adopted to measure cardiac hemodynamics, and near-infrared spectroscopy was employed to assess perfusions in the frontal cerebral lobe (Δ[THb](FC)) and vastus lateralis muscle (Δ[THb](VL)). The results demonstrated that the Y-C group had higher levels of cardiac output, Δ[THb](FC), and Δ[THb](VL) during exercise than the O-C group. Moreover, these cardiac/peripheral hemodynamic responses to exercise in HF-III group were smaller than those in both HF-II and O-C groups. Although the change of cardiac output caused by exercise was normalized, the amounts of blood distributed to frontal cerebral lobe and vastus lateralis muscle in the HF-III group significantly declined during exercise. The HF-III patients had lower oxygen-uptake efficiency slopes (OUES) and greater Ve-Vo(2) slopes than the HF-II patients and age-matched controls. However, neither hemodynamic nor ventilatory response to exercise differed significantly between the HF-II and O-C groups. Cardiac output, Δ[THb](FC), and Δ[THb](VL) during exercise were directly related to the OUES and Vo(2peak) and inversely related to the Ve-Vco(2) slope. Moreover, cardiac output or Δ[THb](FC) was an effect modifier, which modulated the correlation status between Δ[THb](VL) and Ve-Vco(2) slope. We concluded that the suppression of cerebral/muscle hemodynamics during exercise is associated with ventilatory abnormality, which reduces functional capacity in patients with HF.     

Left ventricular function during graded exercise in patients with coronary artery disease and in control subjects.

The left ventricular function of 30 patients with coronary artery disease and 11 control subjects was studied by electrocardiography gated cardiac blood pool scintigraphy as the participants lay on their backs and either rested or exercised on a cycle ergometer at graded levels on intensity. The control subject showed a progressive increase in ejection fraction from rest (51% +/- 7%) to intermediate (56% +/- 10%, P less than 0.05) and maximum levels of exercise (64% +/- 10%, P less than 0.001). All the patients showed a decrease in ejection fraction from rest (42% +/- 16%) to their maximal level of exercise (36% +/- 11%, P less than 0.001). However, the response of some of the patients to intermediate exercise ranged from a decrease or no change to an increase in ejection fraction. Thus, exercise at maximal intensity is necessary to induce the left ventricular dysfunction that is diagnostic of coronary artery disease.     

血浆IIA分泌型磷脂酶A2水平与冠脉支架术后再狭窄关系

目的：测定稳定型冠心病患者支架植入术（percutanous coronary intervention,PCI）前血浆IIA分泌型磷脂酶A2（group IIA secretory phospholipase A2,IIA-sPLA2）的水平,以探讨该酶与冠脉支架术后再狭窄的可能关系。方法：稳定型冠心病行PCI患者63例,非冠心病患者39例,健康正常对照组42例,分别取外周静脉血测定血浆IIA-sPLA2酶浓度。PCI患者6个月后复查造影。结果：PCI患者术前该酶浓度显著高于正常对照组（P〈0．05）,支架内再狭窄率34．9％,再狭窄（restenosis,RS）患者支架术前该酶水平与无再狭窄患者该酶水平无统计学差异（P〉0．05）。结论：PCI患者术前血浆IIA-sPLA2酶浓度显著高于正常对照组,但可能与支架术后再狭窄无关。     

The Diagnostic Value of Treadmill Exercise Test Parameters for Coronary Artery Disease

The aim of this study was to determine the diagnostic value of treadmill exercise test (TET) in patients with coronary heart disease (CHD) by comparing the diagnostic conclusions with coronary angiography (CAG). Patients (445) with CHD and suspected CHD underwent TET and CAG, and the corresponding diagnostic conclusions were compared. (1) Out of the 200 cases that had the positive result with TET, 150 cases had been diagnosed CHD by means of CAG; Out of the 245 cases that had the negative result during TET, only 39 cases had been diagnosed CHD by means of CAG. The sensitivity, specificity, positive predictive value, negative predictive value, the false positive incidence, the false negative incidence, and agreement rate in diagnosis of CHD by TET were 79.36, 80.40, 75.00, 84.08, 25.00, 15.92, and 80.00 %, respectively. The patients with multi-vessel disease had a higher positive rate of TET as compared with those with single-vessel disease (P < 0.05). (2) The parameters for 189 cases positive CAG (patients diagnosed CHD by CAG) and 256 cases negative CAG (the control group), including the general exercise time, peak heart rate, and the beginning time of ST depression, were lower than that of control group (P < 0.05). However, the extent of ST depression and duration of ST depression were higher in these patients than in the control group (P < 0.05). (3) 189 cases positive CAG, include 87 cases of single coronary artery and 102 cases of binary or more coronary arteries (the control group). The parameters, including the general exercise time, peak heart rate, and the beginning time of ST depression, were lower than the control group (P < 0.05). However, the extent of ST depression and duration of ST depression were higher in these patients than the control group (P < 0.05). The TET is valuable for noninvasive diagnosis of CHD, especially for patients with multi-vessel disease.     

Cardiac resynchronization therapy-defibrillator implantation guided by electroanatomic mapping in a young adult patient with congenital heart disease

Cardiac resynchronization therapy-defibrillator (CRT-D) implantation is a therapeutic option for adult patients with congenital heart disease (CHD), bundle branch block, reduced ejection fraction and symptoms of heart failure. A new implantation approach guided by the electroanatomic mapping (EAM) has been developed to overcome some issues of the standard technique: non-responder patients, high x-ray exposure and use of iodinated contrast medium for coronary sinus angiography. This approach has not been previously described in the CHD population. We report a case of EAM-guided approach for CRT-D implantation in a young adult patient with CHD.     

Exhaled nitric oxide and exercise performance in heart failure

BACKGROUND: In heart failure abnormalities of pulmonary function are frequently observed particularly during exercise, which is characterized by hyperpnea, low tidal volume, early expiratory flow limitation and reduced lung compliance. Exhaled nitric oxide (NO) is increased in asthma. We evaluated whether a correlation between exhaled NO and lung mechanics exists during exercise in heart failure. METHODS: We studied 33 chronic heart failure patients and 11 healthy subjects with: a) standard pulmonary function, b) lung diffusion for carbon monoxide (DLCO) including its subcomponents, capillary volume and membrane resistance and eNO both at rest and during light exercise, c) maximal cycloergometer cardiopulmonary exercise test. RESULTS: Forced expiratory volume in 1 second (FEV1) was reduced in heart failure patients (83 +/- 17% of predicted) as was DLCO (75 +/- 18% of predicted) due to reduced membrane resistance (32.6 +/- 10.3 ml/mmHg/min vs. 39.9 +/- 6.9 in patients vs. controls, p < 0.02). eNO was lower in patients vs. controls (9.7 +/- 5.4 ppm vs. 14.4 +/- 6.4, p < 0.05) and was, during exercise, constant in patients and reduced in controls. No significant correlation was found between eNO and lung function. Vice-versa eNO changes during exercise were correlated with peak exercise oxygen consumption (r = 0.560, p < 0.001). CONCLUSIONS: The hypothesis of a link between eNO and lung function in heart failure was not proved. The correlation between eNO changes during exercise and peak VO2 might be due to hemoglobin oxygenation which binds NO to hemoglobin.     

血浆IIA 分泌型磷脂酶A2 水平与冠脉支架术后再狭窄关系

目的:测定稳定型冠心病患者支架植入术(percutanous coronary intervention,PCI)前血浆IIA分泌型磷脂酶A2(group IIAsecretory phospholipase A2,ⅡA-sPLA2)的水平,以探讨该酶与冠脉支架术后再狭窄的可能关系。方法:稳定型冠心病行PCI患者63例,非冠心病患者39例,健康正常对照组42例,分别取外周静脉血测定血浆ⅡA-sPLA2酶浓度。PCI患者6个月后复查造影。结果:PCI患者术前该酶浓度显著高于正常对照组(P<0.05),支架内再狭窄率34.9%,再狭窄(restenosis,RS)患者支架术前该酶水平与无再狭窄患者该酶水平无统计学差异(P>0.05)。结论:PCI患者术前血浆ⅡA-sPLA2酶浓度显著高于正常对照组,但可能与支架术后再狭窄无关。     

Metabolic consequences of reduced frequency breathing during submaximal exercise at moderate altitude

The intention of this study was to determine the metabolic consequences of reduced frequency breathing (RFB) at total lung capacity (TLC) in competitive cyclists during submaximal exercise at moderate altitude (1520 m; barometric pressure, PB = 84.6 kPa; 635 mm Hg). Nine trained males performed an RFB exercise test (10 breaths.min-1) and a normal breathing exercise test at 75-85% of the ventilatory threshold intensity for 6 min on separate days. RFB exercise induced significant (P less than 0.05) decreases in ventilation (VE), carbon dioxide production (VCO2), respiratory exchange ratio (RER), ventilatory equivalent for O2 consumption (VE/VO2), arterial O2 saturation and increases in heart rate and venous lactate concentration, while maintaining a similar O2 consumption (VO2). During recovery from RFB exercise (spontaneous breathing) a significant (P less than 0.05) decreases in blood pH was detected along with increases in VE, VO2, VCO2, RER, and venous partial pressure of carbon dioxide. The results indicate that voluntary hypoventilation at TLC, during submaximal cycling exercise at moderate altitude, elicits systemic hypercapnia, arterial hypoxemia, tissue hypoxia and acidosis. These data suggest that RFB exercise at moderate altitude causes an increase in energy production from glycolytic pathways above that which occurs with normal breathing.     

组织多普勒成像对射血分数正常的心衰患者左心功能评价

目的:探讨组织多普勒成像(TDI)技术评价射血分数正常的心衰患者左室长轴功能特点。方法:选取30名健康人(Ⅰ组)、EF>50%的心衰患者30名(Ⅱ组)和EF<50%的心衰患者30名(Ⅲ组)作为研究对象,采用TDI在二尖瓣环室间隔(ivs)、侧壁(l)、前壁(a)、后壁(p)、下壁(d)测量其Sm、DSm、IVCTm、TSm、Em、Am、IVRTm、TEm等指标。结果:Ⅰ组、Ⅱ组、Ⅲ组DSm、Sm逐渐减低,(P<0.05);而IVCTm、TSm逐渐升高(P<0.05);IVRTm、TEm在Ⅰ组、Ⅲ组、Ⅱ组逐渐升高(P<0.05);DSm及TEm在诊断EF>50%心衰患者心功能的指标中ROC曲线下面积最大,同样DSp及TEp在五个位点中ROC曲线下面积最大。结论:射血分数正常的心衰患者存在收缩减低;DSm及TEm是诊断EF>50%心衰患者心功能比较有效的指标;后壁是诊断的最佳位点。     

Ventilation in conscious dogs during acute and chronic hypercapnia.

Minute ventilation was measured in conscious dogs, at rest and during exercise (1 mph), over 60 min immediately following the acute inhalation of 5% carbon dioxide in air and at 2, 4, 7, and 14 days while breathing the same gas mixture in a chamber. The dogs were also studied in the immediate period of air recovery from chronic hypercapnia and 1 day later. Control studies were carried out with the dogs breathing air in the chamber under comparable conditions. A triphasic ventilation change was ovserved in dogs at rest over the 14 days of hypercapnia. After an initial marked increase in ventilation during acute hypercapnia, ventilation returned to control levels by 2 days and then appeared to be elevated above control studies from 4 to 14 days at a time when blood acid-base balance became compensated. When the same dogs were studied during exercise, ventilation was also not different from air control at 2 days of hypercapnia; however during exercise, unlike the resting studies, there was only a tendency for a secondary increase in ventilation at 7 and 14 days of hypercapnia. During the immediate recovery from chronic hypercapnia when the dogs breathed air there was no evidence of hypoventilation either at rest or exercise despite arterial alkalosis. At 24 h of recovery it appeared that dogs while at rest had a slightly reduced ventilatory response to 5% carbon dioxide relative to control studies. The findings provide suggestive evidence that other factors, in addition to acid-base balance, might contribute to the regulation of ventilation during chronic hypercapnia and the recovery from chronic hypercapnia.