Effect of cold air inhalation and isometric exercise on coronary blood flow and myocardial function in humans

Abstract

Muller MD, Gao Z, Drew RC, Herr MD, Leuenberger UA, Sinoway LI. Effect of cold air inhalation and isometric exercise on coronary blood flow and myocardial function in humans. J Appl Physiol 111: 1694 -1702, 2011. First published September 22, 2011 doi:10.1152/japplphysiol.00909.2011.-The effects of cold air inhalation and isometric exercise on coronary blood flow are currently unknown, despite the fact that both cold air and acute exertion trigger angina in clinical populations. In this study, we used transthoracic Doppler echocardiography to measure coronary blood flow velocity (CBV; left anterior descending coronary artery) and myocardial function during cold air inhalation and handgrip exercise. Ten young healthy subjects underwent the following protocols: 5 min of inhaling cold air (cold air protocol), 5 min of inhaling thermoneutral air (sham protocol), 2 min of isometric handgrip at 30% of maximal voluntary contraction (grip protocol), and 5 min of isometric handgrip at 30% maximal voluntary contraction while breathing cold air (cold ϩ grip protocol). Heart rate, blood pressure, inspired air temperature, CBV, myocardial function (tissue Doppler imaging), O2 saturation, and pulmonary function were measured. The rate-pressure product (RPP) was used as an index of myocardial O2 demand, whereas CBV was used as an index of myocardial O2 supply. Compared with the sham protocol, the cold air protocol caused a significantly higher RPP, but there was a significant reduction in CBV. The cold ϩ grip protocol caused a significantly greater increase in RPP compared with the grip protocol (P ϭ 0.045), but the increase in CBV was significantly less (P ϭ 0.039). However, myocardial function was not impaired during the cold ϩ grip protocol relative to the grip protocol alone. Collectively, these data indicate that there is a supply-demand mismatch in the coronary vascular bed when cold ambient air is breathed during acute exertion but myocardial function is preserved, suggesting an adequate redistribution of blood flow. blood pressure; sympathetic nervous system; oxygen consumption; handgrip EXPOSURE TO COLD TEMPERATURES causes many physiological adjustments, most of which help prevent a fall in core body temperature. Specifically, peripheral vasoconstriction and shivering both raise blood pressure and effectively increase the work of the heart. These are known triggers of angina in clinical populations (33). Cardiac death is highest in the winter months, even in people who spend little time outdoors (45,54). While the effects of lowered skin temperature on cardiovascular function have been extensively studied (10,29,59,60), other mechanisms likely play a role in this process.Physical perturbation of the oropharynx and larynx elevates blood pressure in clinical settings (18,34), and laryngeal cold receptors have been identified in animals (38, 51). Previous studies (26,28,35,37) have shown that blood pressure, heart rate, and/or muscle sympathetic nerve activity are increased with cold air breathing in healthy humans. Acu...

Peripheral venous distension elicits a blood pressure raising reflex in young and middle-aged adults

“…The finger cuff used was servo-controlled and calibrated to the manufacturer's recommendations (Finometer; Finapres Medical Systems, Amsterdam, The Netherlands). Finger pressures were level corrected post hoc to match the baseline finger pressure to baseline brachial artery pressure (Dinamap Dash 2000; GE Medical Systems, Milwaukee, WI) as done previously (23). Cardiac output and total peripheral resistance were estimated from the finger pressure waveform using the validated (32) model flow technique described elsewhere (14,15,32).…”

Deleterious Effects of Cold Air Inhalation on Coronary Physiological Indices in Patients With Obstructive Coronary Artery Disease

“…First, similar to other physiological studies investigating the effects of cold,5, 24, 25 the sample size was small, which limits extrapolation. Because this is a hypothesis‐generating descriptive study, it is difficult to differentiate 1 association in a hemodynamic variable from another and we did not correct for multiple comparisons.…”

“…The pathophysiology of sudden cardiac death during vigorous exertion in cold air is unclear but likely to be multifactorial 4, 5, 6, 7. One of the triggering events may be the deleterious effect of cold air on coronary blood flow 5, 8.…”

“…One of the triggering events may be the deleterious effect of cold air on coronary blood flow 5, 8. Patients with obstructive coronary stenoses have less coronary vasodilator reserve and maybe particularly vulnerable to such deleterious effects 9.…”

The eco–biological–behavioural perfect storm that follows heavy snowfall

“…It incorporates repetitive dynamic aerobic and resistance activity, which induces a Valsalva manoeuvre and places disproportionate workloads on arm rather than leg muscles, resulting in raised heart rate, blood pressure and myocardial oxygen demand. 1 Such effects are exacerbated by the vasoconstricting and sympathovagal effects of cold-air inhalation, 2 which together may conspire to precipitate myocardial ischemia, plaque rupture, coronary artery thrombosis or arrhythmias. 3 Other patient factors such as underlying cardiopulmonary fitness, self-pacing, 4 circadian variation and the time of snow clearance, 5 and the use of automated or semi-automated snow removal devices, can further modify cardiovascular responsiveness.…”