Mahesh Rastogi (54) collapsed during his walk one morning this winter from what friends thought was fatigue. But, he had suffered a heart attack. “Exposure to cold caused Rastogi’s arteries to constrict.
His blood pressure shot up, precipitating an attack,” said Dr Naresh Trehan, director, Escorts Heart Institute and Research Centre, New Delhi.
Cold weather increases the risk of heart attacks and strokes in people with high blood pressure, with those over 60 being at greatest risk. In Delhi, hospital admissions for heart attacks rose 15 to 30 per cent in December 2006 as compared to June.
In Mumbai, said Dr Harish Mehta, consulting cardiologist at PD Hinduja Hospital: “There is a rise in the number of heart attacks during winter”. Pollution combined with the cold, he added, was the main reason. “It constricts blood vessels and the aged become more prone to heart attacks,” said Mehta.
Trehan added: “In the winter, the body requires more blood to maintain body temperature. People with marginal heart disease can suddenly develop symptoms or have an attack.”
Dr O.P. Yadava, CEO and chief cardiac surgeon at the National Heart Institute in Delhi, explained that for every degree that the temperature drops, the upper blood pressure (systolic) rises by 1.3 mm of mercury. Lower blood pressure (diastolic) rises by 0.6 mm.
The cold also activates the sympathetic system — which is responsible for the ‘fight or fright syndrome’ — that increases the secretion of adrenaline and nor-adrenaline that further increase blood pressure and the heart rate, and raise the body’s oxygen demand.
“Cold increases viscosity or thickness of the blood, which causes increased clot formation in the arteries, leading to an attack or stroke,” says Dr Purshottam Lal, chairman of Metro Heart Institute in Delhi.
The solution is to protect yourself from cold and infection. “Infection leads to inflammation of the arteries, a major risk. You can protect yourself by taking walks in the sunshine,” said Dr Ashok Seth, chief cardiologist, Max Heart and Vascular Institute.