Every winter, 52-year-old Monika Dandona ensures that her husband, Gurudayal Dandona, sits snug and warm, clad in his woollens at their house in Ghaziabad, Uttar Pradesh. She is his primary caregiver — Gurudayal had a bypass surgery in 2017.
At the onset of winter, he feels chest discomfort and needs to be given chest rubs occasionally, mainly for warmth and to make him feel better. Monika says that the doctor has advised Gurudayal to keep himself warm and stay indoors to maintain a desirable body temperature.
“The doctor explained to us that during the winters the blood becomes thicker, affecting its normal flow,” she says.
Gurudayal also experiences similar bouts of discomfort during the peak summer season.
Seasonal impact on heart health
“Our body is designed to work in a certain range of temperature, and when you are exposed to excessive heat and cold, the dysfunction of your muscles starts — including that of the heart, which is also a muscle,” says Dr Mohit Singh Tandon, consultant, non-invasive cardiology, Fortis Escorts Heart Institute, Okhla, Delhi.
Dr Tandon says every year several cases of heart attack and cardiac arrest are reported across different geographies due to the heat or drop in temperature. “Those with pre-existing cardiac issues, the elderly and sometimes newborns and babies who are less than a year old are the vulnerable ones,” he says.
A metanalysis by researchers Cuiqing Liu, Zubin Yavar and Qinghua Sun published in the American Journal of Physiology in December 2015 points out an association between cold (temperature) and adverse cardiovascular effects since the 1940s. In general, mortality is usually lowest around a certain temperature and increases at lower or higher temperatures.
Heart health in summer
Scorching summers also have an impact on cardiac health. “Water loss from the body and dehydration can affect the heart, because when people sweat profusely not only are they losing sweat but also the volume of plasma in the blood reduces,” says Dr Divya Marina Fernandes, consultant, heart failure specialist & interventional cardiologist, Aster RV Hospital, Bengaluru.
Plasma helps maintain body temperature by absorbing and releasing heat as and when the body requires.
Dr Fernandes says extreme heat also increases blood pressure, resulting in variations in the heart rate — which in extreme cases could lead to cardiac complications. She also says that the amount of oxygen needed for the heart in such a condition is higher, which leads to symptoms of chest pain, breathlessness and loss of consciousness due to sustained inadequate oxygen supply.
According to the British Heart Foundation, hot weather means the body has to work harder to keep its core temperature at normal levels, and this puts extra strain on the heart, lungs and kidneys. This means that a person can be at greater risk if they have a heart condition. So, it’s particularly important to stay cool and hydrated in such weather.
Dr Tandon says an underlying heart condition could lead to sweating and dizziness. “It is best to exercise and walk in the morning or late evening, when the temperature is not too high,” he says. It is advisable to keep the body cool and stay in a cooler environment, rather than outdoors.
Dr Fernandes recommends regular baths and showers or an ice pack if needed. “Eat small and light meals,” she says.
Heart attack risk in winter
Extreme cold weather too can put pressure on the heart and raise blood pressure.
“Blood pressure is mostly higher during the winter and lower during the summers,” says Dr Tandon.
The blood vessels respond to severe cold by becoming narrower (constriction). Since more pressure is required to push blood through the narrowed veins and arteries, the blood pressure increases.
“Cold weather can increase your heart rate, leading to increase in the oxygen demand,” Dr Fernandes says. “If there is an associated infection due to the cold temperature, it puts an additional strain on the heart.”
According to Dr Tandon, both of these conditions can lead to cardiac arrest, which is the end result of either a massive heart attack or ventricular fibrillation (arrhythmia) or abnormal heart rhythm.
Heart health: precautions during summers, winters
While most young and healthy people tolerate weather changes well, the risk factors usually affect those above the age of 65. “That’s because as we age the exercising capacity of the heart is reduced,” says Dr Fernandes. “Moreover, pre-existing diseases like high cholesterol, hypertension and diabetes also add up to the risk.”
People with a previously diagnosed heart condition, uncontrolled diabetes, high cholesterol or hypertension may find it difficult to adjust to harsh weather conditions.
Dr Mohit says those on medications like beta blockers (that help bring the heart rate down) need to be cautious so the heartbeat does not slow down further.
Also, people who need diuretics (medicines that remove excessive fluid from the body) are at a higher risk of getting dehydrated due to water loss.
Dr Fernandes’ advice for people with heart conditions is a simple one: go slow. Exercising outdoors in extreme weather conditions is a big no-no. If exercising in the summer, drink adequate fluids and stay hydrated. During the winter, strenuous exercises in extreme cold is not safe for heart patients. Such individuals should also avoid smoking and excessive alcohol intake in both weather conditions.
There is a seasonal effect on cardiac health. Experts says people with existing heart conditions are at higher risk of cardiac complications due to temperature fluctuations. The main reason is vascular, mainly variation in blood viscosity leading to increase in blood pressure.