Exposure to a cold environment (15°C vs 25°C) significantly increased mean systemic arterial pressure during exercise (110 vs 92 mm Hg; p<0.001) and total peripheral resistance.
Does exposure to a cold environment alter circulatory responses at rest and during exercise in patients with and without coronary artery disease?
Cold exposure increases peripheral resistance and arterial pressure, which augments myocardial oxygen demand and provides a physiological basis for cold-induced angina.
Absolute Event Rate: 110% vs 92%
p-value: p=<0.001
The physiologic basis for the frequent complaint of worsening of symptoms in a cold environment was investigated in six patients with and five without coronary-artery disease, at rest and during identical levels of mild upright exercise at 25 and 15°C, with similar results. Significantly higher at the lower temperature were mean systemic arterial pressure (105 vs 92 mm of mercury at rest and 110 vs 92 during exercise; p less than 0.001), total peripheral resistance (1821 vs 1609 dynes-sec-cm-5 at rest, 1213 vs 993 during exercise; p less than 0.02) and left ventricular minute work (6.5 vs 5.7 kg-m at rest, 10.9 vs 9.0 during exercise; p less than 0.001). Exposure to cold did not change heart rate, cardiac output or stroke volume at rest or during exercise. These results indicate that a cold environment increases peripheral resistance at rest and during exercise. The consequent rise in arterial pressure, by augmenting myocardial oxygen requirements, would thus more readily provoke an attack of angina.
Epstein et al. (1969) studied Coronary-artery disease (n=11). Reduction in environmental temperature (15°C) vs. 25°C environmental temperature was evaluated on Mean systemic arterial pressure during exercise (mm Hg) (p=<0.001). Exposure to a cold environment (15°C vs 25°C) significantly increased mean systemic arterial pressure during exercise (110 vs 92 mm Hg; p<0.001) and total peripheral resistance.