Results of a Johns Hopkins-led study have identified a possible link between a history of sudden drops in blood pressure and the most common form of irregular heartbeat. The study suggests that a bout of orthostatic hypotension — a steep blood pressure drop that occurs when a person stands up after a period of lying down — appears to be associated with an overall 40 percent increase in the risk of developing atrial fibrillation over the following two decades. While a simple, inexpensive doctor’s office test can check for orthostatic hypotension, the researchers caution that the condition itself does not generally need treatment, nor have they demonstrated that it is a cause of atrial fibrillation. They further note that because atrial fibrillation is often present without causing noticeable symptoms, some people may already have the rhythm disturbance before an episode of orthostatic hypotension, though they tried to exclude those subjects from the study. But the researchers say their findings do suggest the need for further study and that clinicians who diagnose orthostatic hypotension in their patients need to be more vigilant than they otherwise might be in watching out for atrial fibrillation. The arrhythmia is an underdiagnosed condition that increases the risk of stroke fivefold, as well as risks of heart failure and dementia. People with atrial fibrillation are often treated with blood thinners to reduce the risk of stroke, and with other medications that regulate the rate and rhythm of the heartbeat. The findings were published last week in the journal PLOS ONE. “We hope our research will sensitize physicians to a possible link between orthostatic hypotension and atrial fibrillation, and that they will go the extra step to see if something more serious is going on when patients experience rapid blood pressure fluctuations,” says study leader Sunil K. Agarwal, M.D., M.P.H., Ph.D., a fellow in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine. “We want this on their radar screens.” For the study, the researchers followed 12,071 African-American and white men and women ages 45 to 64 years who were enrolled in the Atherosclerosis Risks in Communities (ARIC) study. From 1987 to 1989, each subject had a baseline visit during which information on socioeconomic indicators, medical history, family history, cardiovascular disease risk factors, serum chemistries, electrocardiograms (ECGs), medication use and anthropometrics was collected. Three follow-up visits were conducted, as well as annual telephone interviews and active surveillance of hospitalizations and death. Five percent of the subjects (603 of them) were diagnosed with a rapid drop in blood pressure when going from lying down to standing up. The authors defined orthostatic hypotension as a 20 mmHg or greater drop in systolic blood pressure or a dip of at least 10 mmHg in diastolic pressure. Those who had a history or symptoms of atrial fibrillation at baseline were excluded from the study. During an average follow-up of 18.1 years, 1,438 (11.9 percent) of the study participants developed atrial fibrillation. Those with orthostatic hypotension, after accounting for factors such as race, age, gender and other common risk factors for the arrhythmia, were 40 percent more likely than those without orthostatic hypotension to develop an irregular heartbeat. Atrial fibrillation was identified by 12-lead ECGs recorded during three follow-up visits at three-year intervals through 1998, and by hospitalizations and/or death certificates through 2010. The 40 percent increased risk associated with atrial fibrillation for patients with fluctuating blood pressure was the same increase in risk associated with subjects who had diabetes or high blood pressure. Atrial fibrillation is the most common type of arrhythmia, or problem with the rate or rhythm of the heart. During an arrhythmia, the heart can beat too fast, too slow or with an irregular rhythm. Atrial fibrillation affects approximately 3 million people in North America, and the prevalence is projected to double by 2050. It occurs when the upper chambers of the heart, the atria, beat chaotically and usually rapidly out of coordination with the two lower chambers of the organ. During atrial fibrillation episodes, blood may pool inappropriately in the upper chamber, forming clots that can travel to the brain and hindering the healthy function of the heart, Agarwal says. Blood thinner treatment has been shown to dramatically reduce stroke risk in these patients by more than half, but many don’t take the medication because they are unaware they have the condition. Symptoms include heart palpitations, shortness of breath and weakness. Agarwal says doctors don’t routinely test for orthostatic hypotension. It is done by having the patient lie down for two to five minutes while having blood pressure tested several times, then standing up and having the same readings taken again after two minutes. Sometimes a patient with orthostatic hypotension will feel lightheaded and dizzy upon standing, but not always. “We need more research into whether there is any sort of causal relationship between orthostatic hypotension and atrial fibrillation, or whether it is simply a marker of dysfunction of autonomic nervous system or generally poor health,” he says. This research was sponsored by the National Institutes of Health’s National Heart, Lung and Blood Institute (N01-HC-55015, 55016, 55018, 55019, 55020, 55021, and 55022 and T32-HL-007779 and T32HL007024). Additional funding for this study was provided by the American Heart Association (09SDG2280087). Researchers from the Mayo Clinic, the University of Minnesota, the University of North Carolina and the Wake Forest University School of Medicine also took part in this study. Other researchers from Johns Hopkins include Seamus P. Whelton, M.D., M.P.H., and Josef Coresh, M.D., Ph.D. Orthostatic hypotension, also called postural hypotension, is defined as a sudden drop in blood pressure caused by a change in posture, such as when a person stands up quickly. When a person stands up after sitting or lying down, blood normally pools in the legs because of gravity. The body then works to push blood upward to supply the brain with oxygen. If the body is unable to do this sufficiently, blood pressure falls, which may lead to symptoms, such as dizziness, blurred visions, or fainting. Hypotension, or low blood pressure, occurs when the blood pressure in the arteries falls below normal levels. The heart pumps blood around the body through blood vessels. These tubular structures include arteries, veins, and capillaries. Blood pressure is a measure of the force of the blood on the walls of the arteries as it pumps through them. Blood pressure is measured in millimeters of mercury (mmHg) and has two figures:
A systolic blood pressure reading of 120 mmHg and a diastolic blood pressure of 80mmHg or 120/80 are considered normal. A person with a reading of 90/60 mmHg or lower is considered to have hypotension or low blood pressure. People who have orthostatic hypotension often experience a drop in blood pressure of about 20/10 mmHg within 3 minutes of standing. Low blood pressure does not usually require treatment. If a person experiences regular symptoms of orthostatic hypotension, however, they should see a doctor. Orthostatic hypotension is common among people who are 65 or older because the body’s ability to react to drops in blood pressure can slow down as a person ages. Figures cited in research by the National Center for Biotechnology Information estimate that orthostatic hypotension is prevalent in around 18 percent of men and women aged 65 or older in the United States. The same study noted that cases of orthostatic hypotension among the elderly account for 35 percent of hospital admissions in the U.S. Loss of fluid within the blood vessels is the most common cause of symptoms linked to orthostatic hypotension. This could be due to dehydration brought about by diarrhea, vomiting, and the use of medication, such as diuretics or water pills. This medication helps the body get rid of excess water and salt through urine. Loss of blood, anemia, and other conditions that result in a lower red blood count are also likely causes. When there are fewer red blood cells available to carry oxygen in the bloodstream, dizziness and light-headedness may occur. Some medications, such as beta-blockers and antidepressants, can also trigger symptoms linked to orthostatic hypotension. Working or exercising in hot weather or being bedridden for a prolonged period can also lead to these symptoms. Parkinson’s disease, pregnancy, and heart conditions such as irregular heart rhythms and valve disease are also known to cause symptoms connected to orthostatic hypotension. Share on PinterestDizziness, blurred vision, and feeling faint may be symptoms of orthostatic hypotension. The symptoms of orthostatic hypotension include:
These symptoms usually go away as the body slowly adjusts to an upright position, or after sitting or lying down for several minutes. Anyone who experiences any of these conditions regularly should seek medical advice immediately. ComplicationsA common complication of orthostatic hypotension is falling over as a result of losing consciousness, which could cause serious injuries. The symptoms could also mask more serious conditions. These include cardiovascular diseases, such as heart failure and heart rhythm problems. The sudden drops in blood pressure caused by orthostatic hypotension are a risk factor for strokes because of the reduced blood supply to the brain. If someone experiences any of the above symptoms, their doctor will look into their medical history. If needed, the doctor will then conduct tests to find out if an underlying condition or illness is causing the symptoms. For example, if a particular medication is causing the blood pressure to drop, the doctor may adjust the dosage or recommend a switch to another drug. A head-up tilt table test will look at how a person’s blood pressure reacts to changes in their body’s position. During this test, a person lies on a table that is slowly tilted upward. Blood tests can show whether someone has low blood sugar or a low number of red blood cells, which are both signs of low blood pressure. An electrocardiogram (ECG or EKG), which monitors the heart’s electrical signals, can uncover irregularities in heart rhythm and problems with blood and oxygen supply to the heart. An ultrasound of the heart, or echocardiogram, assesses the heart valves using sound waves and could uncover underlying disorders. A stress test can be conducted where a doctor monitors the heart while the person is exercising or after being given medication. There are several ways of managing or preventing orthostatic hypotension, most of which do not involve the use of medication.
Severe cases of orthostatic hypotension can be treated with drugs to raise blood pressure. |