Harvard Heart Letter

How winter’s chill can challenge your heart

A few simple precautions can minimize your risk.

Every time you venture out into the bone-shivering, teeth-chattering cold of a Northern winter, your heart and blood vessels kick into overdrive to keep your internal organs cozy. To accomplish this feat, the tiny blood vessels in outlying areas such as the fingers and toes constrict to stem the loss of body heat into the environment. The flip side of this protective maneuver is that the heart must beat against extra force to overcome the resistance it meets in the narrowed vessels.

Supply and demand mismatch

Although this chain of events is a normal physiological response, in certain individuals, it may lead to a situation where body tissues—including the heart itself—need more blood than the cardiovascular system can supply. “The constriction of blood vessels increases resistance to blood flow, thereby increasing the workload of the heart,” says Dr. Viviany Taqueti, a cardiologist at Harvard-affiliated Brigham and Women’s Hospital. Also, winter weather often puts you in situations that call for more physical exertion, such as walking briskly against a strong wind or digging your car out of the snow.

Most people with a healthy circulatory system can withstand the rigors of cold weather. That’s not always true for people with existing heart disease, whether that’s narrowing in the coronary arteries caused by plaque or a thickening of heart muscle from longstanding high blood pressure. “They may experience symptoms such as chest pain or shortness of breath because of a mismatch in the available supply and demand of oxygen to the heart,” says Dr. Taqueti. In rare cases, this added strain may contribute to a heart attack.

Smart precautions

You can minimize the impact of cold weather on your heart by taking steps to avoid situations that are likely to put you at risk.

Don’t overexert. Remember that your heart is already working overtime to compensate for the cold temperatures. Therefore, don’t push yourself with strenuous activities such as shoveling heavy snow or partaking in vigorous outdoor exercise unless you are in good physical shape.

Keep your body temperature steady. Put on warm outerwear including coat, gloves, and hat before facing the elements. This will guard against hypothermia, in which the body’s internal temperature falls too low. Likewise, dress in layers that you can peel off if you get too warm. Overheating can lead to an abrupt and potentially dangerous drop in blood pressure.

Get a flu shot. A bout of seasonal flu can trigger a heart attack in people already at risk for heart disease. The flu causes a fever, which can make your heart beat faster. It can also cause dehydration, which can have a similar effect as the heart beats faster to maintain your blood pressure.

Keep your prescriptions filled. Icy conditions can make it difficult to get to the pharmacy to pick up a prescription, so make sure not to let your supply of heart medicines run low.

Heed the warning signs

If you notice chest pain or other heart symptoms in cold weather, stop what you’re doing and call your doctor, says Dr. Taqueti. “Just like an exercise treadmill test, stressors such as cold can reveal underlying cardiovascular disease,” she says.

Why do my fingers turn blue in the cold?

Some people have an exaggerated response to cold temperature or emotional stress in which their blood vessels tighten excessively. This is known as Raynaud’s disease, also called Raynaud’s syndrome or Raynaud’s phenomenon.

During an attack of Raynaud’s, the skin on the fingers (and sometimes toes), typically turns white, sometimes progressing to blue or purple, and feels cold to the touch. When warmed, the skin may turn red or return to a normal pink color. About one in 30 people have Raynaud’s, which is usually not serious.

To help prevent attacks:

  • Avoid exposing your hands to cold. Wear gloves in cold weather, and use a cup insulator when you hold a cold beverage.
  • Keep your house warm and always dress appropriately for cold weather.
  • Try to relax and reduce emotional stress with meditation and exercise.
  • Do not smoke, and avoid secondhand smoke, as both can worsen vessel constriction and increase symptoms.
  • Avoid medicines that can narrow blood vessels, including decongestants and diet pills.

If you have an attack, try to end it quickly by warming up your hands. Placing your hands in warm water or against a warm part of your body can help.

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