13 research outputs found
Cardiovascular responses to cold exposure in untreated hypertension
Abstract
Cold weather associates with higher cardiovascular morbidity and mortality in various climates. It is also known that exposure to a cold environment instantly activates sympathetic nervous system and elevates blood pressure (BP) in healthy individuals. Hypertension can increase sympathetic reactivity and arterial stiffness, and could therefore exaggerate these cold-related changes. We implemented an experimental study to assess cardiovascular responses to habitual type of cold exposure among subjects with untreated hypertension.
We selected a random sample of middle-aged men in the city of Oulu, Finland. The recruitment included home BP measurements. 51 untreated hypertensive men and 32 men without hypertension (controls) underwent 15 minutes whole-body cold exposure (temperature -10°C, wind speed 3m/s, winter clothing, standing). Brachial, central aortic, and continuous BP, as well as electrocardiography (ECG) were measured before (15 min), during (15 min), and after (20 min) the exposure. Skin temperature and thermal sensations were also assessed.
The employed exposure increased central and brachial systolic (ca. 25 mmHg) and diastolic (ca. 10 mmHg) BP in both test groups. One fourth of men with mild to moderate hypertension had systolic BP exceeding 200 mmHg while exposed to cold. Small heart rate (HR) reduction was not enough to compensate for the elevated BP, and cardiac workload increased during cold exposure. Cardiac repolarization showed modest arrhythmogenic changes and frequency of ventricular ectopic beats increased slightly in cold conditions. Cold exposure also increased cardiac vagal baroreflex sensitivity in both test groups, whereas an estimate of vascular sympathetic activity increased only among controls. We also found an elevated systolic home BP variability to associate with higher cardiac workload and BP responses to cold.
Moderate cold air exposure substantially increased BP but also activated cardiac vagal regulation among untreated hypertensive and non-hypertensive men. The BP level reached in cold conditions was considerably high in those with hypertension, and especially in those with both hypertension and higher home BP variability. These results are important to health care professionals who treat hypertensive patients. The importance of year-round BP control and proper protection from cold should not be underestimated.TiivistelmÀ
KylmÀÀn sÀÀhÀn liittyvÀ verenkiertoelimistön sairauksien paheneminen on havaittu eri ilmastoissa. TiedetÀÀn myös, ettÀ terveillÀ henkilöillÀ sympaattisen hermoston aktiivisuus ja verenpaine nousevat kylmÀssÀ ympÀristössÀ. Kohonnut verenpaine eli hypertensio voi lisÀtÀ sympaattista reaktiivisuutta ja valtimojÀykkyyttÀ sekÀ siten voimistaa verenkiertoelimistön kylmÀvasteita. Kokeellinen tutkimuksemme arvioi sydÀmen ja verisuoniston vasteita tavanomaiseen kylmÀaltistukseen hoitamatonta hypertensiota sairastavilla henkilöillÀ.
Tutkittavat olivat Oulun vĂ€estöstĂ€ satunnaisesti valittuja keski-ikĂ€isiĂ€ miehiĂ€, joilta mÀÀritettiin verenpaine kotimittauksilla. 51 hoitamatonta hypertensionta sairastavaa miestĂ€ ja 32 miestĂ€, joilla ei ollut hypertensiota (verrokit), altistettiin 15 minuutin ajan kylmĂ€lle (lĂ€mpötila -10 °C, tuuli 3 m/s, talvivaatteet, seisten). Verenpainetta mitattiin olkavarresta, epĂ€suorasti sydĂ€mestĂ€ ja jatkuvana signaalina ennen altistusta (15 min), sen aikana (15 min) ja jĂ€lkeen (20 min). Samalla seurattiin sydĂ€men sĂ€hköistĂ€ toimintaa, iholĂ€mpötiloja ja lĂ€mpötuntemuksia.
KylmÀaltistus kohotti sekÀ sydÀmen ettÀ olkavarren ylÀ- (noin 25 mmHg) ja alapainetta (noin 10 mmHg) molemmissa tutkimusryhmissÀ. NeljÀsosalla lievÀÀ tai kohtalaista hypertensiota sairastavista miehistÀ ylÀpaine kohosi yli 200 mmHg tasolle. Sykkeen lasku ei riittÀnyt tasapainottamaan kohonnutta verenpainetta ja sydÀmen työmÀÀrÀ nousi. SydÀmen rytmihÀiriöherkkyys ja vastaavasti kammiolisÀlyöntien esiintymistiheys olivat myös hieman koholla altistuksen aikana. KylmÀaltistus kasvatti sydÀmen vagaalista barorefleksiherkkyyttÀ molemmissa ryhmissÀ. Verisuonten sympaattinen verenpainevaihtelu kasvoi vain verrokeilla. SydÀmen työmÀÀrÀ ja verenpaine kohosivat kylmÀssÀ enemmÀn heillÀ, joiden verenpaineen vaihtelu kotona oli korkeampi.
Tavanomaista talvipÀivÀÀ vastaava kylmÀaltistus kohotti verenpainetta voimakkaasti, mutta myös aktivoi sydÀmen suojaavaa sÀÀtelyÀ sekÀ hoitamatonta hypertensiota sairastavilla ettÀ verrokeilla. KylmÀssÀ saavutettu verenpainetaso oli merkittÀvÀ heillÀ, joilla oli hypertensio, ja erityisesti heillÀ, joilla oli sekÀ hypertensio ettÀ suurempi kotiverenpainevaihtelu. TÀmÀ tutkimustieto on tÀrkeÀÀ hypertensiopotilaille sekÀ heitÀ hoitaville terveydenhuollon ammattilaisille. Tulokset korostavat ympÀrivuotisen verenpainekontrollin ja kylmÀltÀ suojautumisen tÀrkeyttÀ
Hyvinvointia mukautuvalla ja ÀlykkÀÀllÀ valaistuksella kouluihin ja työympÀristöihin
TiivistelmÀ
Sirkadiaaninen valaistus lisÀÀ hyvinvointia tiloissa, joissa pÀivÀnvalon saatavuus on rajoittunut. Arkkitehtonisen valaistussuunnittelun keinoilla voidaan vaikuttaa kokemukseen moniulotteisesti. Mukautuvan ja ÀlykkÀÀn valaistuksen hyvinvointivaikutuksia tutkittiin muun muassa Rantaroustin koulussa TyrnÀvÀllÀ sekÀ PyhÀsalmen kaivoksen maanalaisissa työympÀristöissÀ
Cardiovascular responses to dynamic and static upper-body exercise in a cold environment in coronary artery disease patients
Purpose
Upper-body exercise performed in a cold environment may increase cardiovascular strain, which could be detrimental to patients with coronary artery disease (CAD). This study compared cardiovascular responses of CAD patients during graded upper-body dynamic and static exercise in cold and neutral environments.
Methods
20 patients with stable CAD performed 30 min of progressive dynamic (light, moderate, and heavy rating of perceived exertion) and static (10, 15, 20, 25 and 30% of maximal voluntary contraction) upper body exercise in cold (â 15 °C) and neutral (+â22 °C) environments. Heart rate (HR), blood pressure (BP) and electrocardiographic (ECG) responses were recorded and rate pressure product (RPP) calculated.
Results
Dynamic-graded upper-body exercise in the cold increased HR by 2.3â4.8% (pâ=â0.002â0.040), MAP by 3.9â5.9% (pâ=â0.038â0.454) and RPP by 18.1â24.4% (pâ=â0.002â0.020) when compared to the neutral environment. Static graded upper-body exercise in the cold resulted in higher MAP (6.3â9.1%; pâ=â0.000â0.014), lower HR (4.1â7.2%; pâ=â0.009â0.033), but unaltered RPP compared to a neutral environment. Heavy dynamic exercise resulted in ST depression that was not related to temperature. Otherwise, ECG was largely unaltered during exercise in either thermal condition.
Conclusions
Dynamic- and static-graded upper-body exercise in the cold involves higher cardiovascular strain compared with a neutral environment among patients with stable CAD. However, no marked changes in electric cardiac function were observed. The results support the use of upper-body exercise in the cold in patients with stable CAD.peerReviewe
The effects of submaximal exercise and cold exposure on blood coagulation parameters in coronary artery disease patients
Abstract
Background: Both exercise and cold exposure increase blood coagulation potential but their combined effects are not known. The purpose of the present study was to assess blood coagulation factors in response to submaximal exercise in the cold environment among patients with stable coronary artery disease (CAD).
Methods: Sixteen men (61.1â±â7.1 years) with stable CAD participated in three 30-min experimental conditions (seated rest in â 15 °C and exercise in bothâ+â22 °C and â 15 °C) in random order. The employed exercise consisted of brisk walking (66â69% of maximal heart rate). Factor VII (FVII), fibrinogen, D-dimer and von Willebrand factor (vWF) were analyzed from blood samples obtained before, immediately and one hour after each experiment.
Results: On average, FVII activity (95% confidence interval, CI) was 123 (108â143) %, 123 (106â140) %, 121 (103â139) % (baseline, recovery 1, recovery 2), fibrinogen concentration (95% CI) 3.81 (3.49â4.12) g/l, 3.71 (3.34â4.08) g/l, 3.65 (3.26â4.05) g/l, D-dimer concentration (95% CI) 0.42 (0.28â0.56) ”g/ml, 0.42 (0.29-.55) ”g/ml and 0.39 (0.29â0.49) ”g/ml, and vWF activity (95% CI) 184 (135â232) %, 170 (128â212) % and 173 (129â217) % after exercise in the cold. Average FVII activity varied from 122 to 123%, fibrinogen concentration from 3.71 to 3.75 g/l, D-dimer concentration from 0.35 to 0.51 ”g/ml and von Willebrand factor activity from 168 to 175% immediately after each three experimental condition.
Conclusions: Our findings suggest that submaximal lower body exercise carried out in a cold environment does not significantly affect blood coagulation parameters among patients with stable CAD
Good safety practice in a randomized controlled trial (CadColdEx) involving increased cardiac workload in patients with coronary artery disease
Abstract
Background: Methodological information acknowledging safety of cardiac patients in controlled medical experiments are lacking. The descriptive report presents one good practice for considering safety in a randomized controlled study involving augmented cardiovascular strain among persons with coronary artery disease (CAD).
Methods: The patients were pre-selected by a cardiologist according to strictly defined selection criteria. Further confirmation of eligibility included screening of health. In addition, assessments of physical capacity by a graded bicycle ergometer test were implemented and safety monitored by an exercise physiologist and medical doctor. In this context, an emergency simulation was also carried out. A total of 18 CAD patients each underwent four different experimental interventions where either temperature (+â22â°C andâââ15â°C) and the level of exercise (rest and brisk walking) were employed for 30âmin in random order (72 experiments). Baseline (20âmin) and follow-up (60âmin) measurements were conducted resting at +â22â°C. ECG, and brachial blood pressure were measured and perceived exertion and symptoms of chest pain inquired throughout the experiments. An emergency nurse was responsible for the health monitoring and at least two persons followed the patient throughout the experiment. A medical doctor was available on call for consultation. The termination criteria followed the generally accepted international guidelines for exercise testing and were planned prior to the experiments.
Results: The exercise test simulation revealed risks requiring changes in the study design and emergency response. The cardiovascular responses of the controlled trials were related to irregular HR, ST-depression or post-exercise hypotension. These were expected and the majority could be dealt on site by the research personnel and on call consultation. Only one patient was encouraged to seek for external health care consultation.
Conclusions: Appropriate prospective design is a key to safe implementation of controlled studies involving cardiac patients and stimulation of cardiovascular function. This includes careful selection of participants, sufficient and knowledgeable staff, as well as identifying possible emergency situations and the required responses.
Trial registration: ClinicalTrials ID: NCT02855905
Cardiovascular responses to dynamic and static upper-body exercise in a cold environment in coronary artery disease patients
Abstract
Purpose: Upper-body exercise performed in a cold environment may increase cardiovascular strain, which could be detrimental to patients with coronary artery disease (CAD). This study compared cardiovascular responses of CAD patients during graded upper-body dynamic and static exercise in cold and neutral environments.
Methods: 20 patients with stable CAD performed 30 min of progressive dynamic (light, moderate, and heavy rating of perceived exertion) and static (10, 15, 20, 25 and 30% of maximal voluntary contraction) upper body exercise in cold (â 15 °C) and neutral (+â22 °C) environments. Heart rate (HR), blood pressure (BP) and electrocardiographic (ECG) responses were recorded and rate pressure product (RPP) calculated.
Results: Dynamic-graded upper-body exercise in the cold increased HR by 2.3â4.8% (pâ=â0.002â0.040), MAP by 3.9â5.9% (pâ=â0.038â0.454) and RPP by 18.1â24.4% (pâ=â0.002â0.020) when compared to the neutral environment. Static graded upper-body exercise in the cold resulted in higher MAP (6.3â9.1%; pâ=â0.000â0.014), lower HR (4.1â7.2%; pâ=â0.009â0.033), but unaltered RPP compared to a neutral environment. Heavy dynamic exercise resulted in ST depression that was not related to temperature. Otherwise, ECG was largely unaltered during exercise in either thermal condition.
Conclusions: Dynamic- and static-graded upper-body exercise in the cold involves higher cardiovascular strain compared with a neutral environment among patients with stable CAD. However, no marked changes in electric cardiac function were observed. The results support the use of upper-body exercise in the cold in patients with stable CAD.
Trial registration: Clinical trial registration NCT02855905 August 2016
Good safety practice in a randomized controlled trial (CadColdEx) involving increased cardiac workload in patients with coronary artery disease
High home blood pressure variability associates with exaggerated blood pressure response to cold stress
Abstract
Background: Exaggerated sympathetic cardiovascular (CV) reactivity to stress associates with elevated risk for clinical and preclinical end points of CV disease. It would be useful to identify these individuals, preferably from feasible measurements commonly used in health care. Our study examined the association between home blood pressure (BP) variability and cardiac workload response to whole-body cold exposure.
Methods: Seventy-five men (55â65 years, 46 hypertensive) measured BP at home twice in the morning and evening for a week. We computed systolic home BP variability as SD of daily means and divided the subjects into groups demonstrating either high or low BP variability. They were exposed to whole-body cold exposure (â10 °C, wind 3 m/second, 15 minutes, winter clothes, standing). BP and heart rate were measured at 3-minute intervals during, and 15 minutes before and after the exposure. Rate-pressure product (RPP) was calculated to represent cardiac workload.
Results: Subjects with high systolic home BP variability demonstrated a greater RPP increase in cold conditions compared to those with low BP variability [mean change from baseline (95% CI): 1,850 (1,450 to 2,250) bpm Ă mm Hg vs. 930 (610, 1,250) bpm Ă mm Hg, P < 0.01]. This was related to the augmented systolic BP change [31(28, 35) mm Hg vs. 23(20, 26) mm Hg, P < 0.01]. Home BP variability correlated with cold-related RPP (rS = 0.34, P = 0.003) and systolic BP (rS = 0.38, P < 0.001) responses.
Conclusions: Moderate whole-body cold exposure increased BP and cardiac workload more among those with higher systolic home BP variability, independently of home BP level. Elevated home BP variability may indicate augmented sympathetically mediated vascular reactivity for environmental stressors.
Public trials registry number: Trial Number NCT02007031
Central aortic hemodynamics following acute lower and upper-body exercise in a cold environment among patients with coronary artery disease
Abstract
Exercise is beneficial to cardiovascular health, evidenced by reduced post-exercise central aortic blood pressure (BP) and wave reflection. We assessed if post-exercise central hemodynamics are modified due to an altered thermal state related to exercise in the cold in patients with coronary artery disease (CAD). CAD patients (nâ=â11) performed moderate-intensity lower-body exercise (walking at 65â70% of HRmax) and rested in neutral (+â22 °C) and cold (ââ15 °C) conditions. In another protocol, CAD patients (nâ=â15) performed static (five 1.5 min work cycles, 10â30% of maximal voluntary contraction) and dynamic (three 5 min workloads, 56â80% of HRmax) upper-body exercise at the same temperatures. Both datasets consisted of four 30-min exposures administered in random order. Central aortic BP and augmentation index (AI) were noninvasively assessed via pulse wave analyses prior to and 25 min after these interventions. Lower-body dynamic exercise decreased post-exercise central systolic BP (6â10 mmHg, pâ<â0.001) and AI (1â6%, pâ<â0.001) both after cold and neutral and conditions. Dynamic upper-body exercise lowered central systolic BP (2â4 mmHg, pâ<â0.001) after exposure to both temperatures. In contrast, static upper-body exercise increased central systolic BP after exposure to cold (7â±â6 mmHg, pâ<â0.001). Acute dynamic lower and upper-body exercise mainly lowers post-exercise central BP in CAD patients irrespective of the environmental temperature. In contrast, central systolic BP was elevated after static exercise in cold. CAD patients likely benefit from year-round dynamic exercise, but hemodynamic responses following static exercise in a cold environment should be examined further
Endothelial function in response to exercise in the cold in patients with coronary artery disease
Abstract
Background: Regular longâterm physical exercise has favourable effects on endothelial function in patients with coronary artery disease (CAD). However, the effects of an acute exercise bout in the cold on endothelial function are not known.
Methods: At first, the effects of moderateâintensity aerobic lowerâbody exercise were assessed in CAD patients (n = 16) in a neutral [+22°C] and cold [â15°C] environment. Secondly, responses to static and dynamic upperâbody exercise in a neutral [+22°C] and cold [â15°C] environment were investigated in CAD patients (n = 15). All experiments were performed in a random order. Endothelial function was measured by flowâmediated dilation (FMD) of the brachial artery in response to reactive hyperaemia, before and after the exposures in a neutral environment.
Results: No significant temperature*exercise*condition (preâpost) interaction was observed in FMD% when comparing rest versus aerobic exercise or static versus dynamic upperâbody exercise. Relative reactive hyperaemia during FMD protocol, measured by changes in shear rate, was elevated after rest compared to aerobic exercise (p = 0.001) and after static compared to dynamic upperâbody exercise (p < 0.001). However, no significant temperature*exercise*condition interaction was observed when FMD% was normalized for shear rate.
Conclusions: Endothelial function to an acute bout of exercise among CAD patients was not modified by the environmental temperature where the exercise was performed. The present findings argue against the hypothesis that exercise in cold environmental conditions impairs endothelial function in patients with CAD