Ask the Doctors July 2012 Issue

Ask The Doctors: July 2012

I experience occasional migraines, but I never thought they were linked to heart problems. A nurse recently told me that she the risks for a stroke or heart attack are higher if you have migraines? Is this true? I have hypertension, but it’s well controlled.

What you were told is true. Persons with a history of migraine headache have been shown to have a risk of stroke or heart attack approximately twice that of persons without such a history. Migraine patients who experience an aura, consisting of visual and sensory disturbances prior to the headache itself, are at even higher risk, especially women under the age of 45 who smoke or use oral contraceptives. The relationship between migraine and cardiovascular events is quite complex. In some rare cases, stroke can occur during a migraine attack, a situation referred to as “migraineous infarction.” However, use of drugs to prevent migraines has not been shown to reduce risk of stroke, so such a mechanism cannot be used to explain the increased cardiovascular risk.

During the migraine aura, a process known as chronic spreading depolarization (CSD) affects neurons and their support cells in the brain. CSD alters the electrolye balance of the brain, causes the release of certain enzymes and hormones, and can affect vascular function. The nature of the chemical “soup” the brain is sitting in will probably influence the blood flow it receives. Other potential causes of increased stroke risk which have been promoted, but for which evidence is sparse, include the actions of specific antibodies, hormones, and neurotransmitters on the brain.

The link between migraines and heart attack may be more indirect. Cardiovascular risk factors such as obesity, pre-diabetes, and abnormal cholesterol levels seem to cluster more frequently in persons with migraine. At the present time, it is generally recommended that migraine patients undergo careful evaluation for cardiovascular risk factors, as well as for evidence of cardiovascular disease. It is reassuring that your high blood pressure is well-controlled, since aggressive treatment of risk factors, both by lifestyle modification (diet, weight loss, exercise, and smoking cessation) and by drug therapy, would appear doubly important in persons such as yourself.

I’m taking a few long flights this summer, but I’m concerned about a blood clot forming while I’m flying. I have mild peripheral artery disease (PAD). How can I stay safe?

Your concerns are understandable, since long-distance airline travel is so common. The overall risk of having a symptomatic deep vein thrombosis (DVT) appears to be a little less than 1 in 5,000 flights. The more flights that one takes in a given time period, and the longer each flight is, the higher the risk of DVT. Systematic reviews of air travelers, including employees and passengers, have found that the risk of developing blood clots in the leg veins is increased by two-to-fourfold by “long-haul” flights (>4 hours). Particularly at risk were those on oral contraceptives, and those who were particularly short, tall, or overweight. Other known risk factors are a history of previous blood clot, age >60 years, cancer, obesity, and flights longer than 12 hours. In your case, PAD does not appear to confer any greater DVT risk.

The flight-related factors that appear to be the most important in increasing the chance of DVT are prolonged sitting, and decreased oxygen content of the air Although controversial, it probably is best to avoid dehydration. Taking aspirin does not clearly influence DVT risk. Until further information emerges, it appears the best way to help avoid DVTs during air travel is to stay hydrated, and to stand up and walk about frequently. It is reasonable to consider wearing compression stockings during the flight, since some studies have shown that this intervention can decrease risk. After discussion with their physicians, patients at highest DVT risk may receive a prescription for shots of low molecular weight heparin.