Ask The Doctors: March 2014
Q. I’m an 83-year-old man who experiences extreme fluctuations in my blood pressure (BP). It gets up to 190/90 at night sometimes and then down to 105/60 during the day. I can’t get a good explanation for why this happens. Any thoughts about causes? And is there a specialist I should see?
A. In the past, we thought that average BP was important to track, while BP variability was not as concerning. However, over the past decade, new evidence suggests that patients like you with BP variability extending into the high range are more likely to experience a stroke or transient ischemic attack (TIA) than those with stably elevated average BP. Such fluctuations also portend a higher risk of developing a life-threatening tear in the aorta, known as an aortic dissection. Brain function seems to degrade faster, as well. Given these risks, clinicians are paying much more attention to BP variability. The first step is to make sure your home monitoring device is functioning correctly, by bringing it in to your doctor’s office and comparing the results with his or her measurement.
Once the accuracy of your BP measurements is verified, ambulatory BP monitoring for 24 hours may be performed. Although inconvenient, this test can reveal the pattern and suggest possible causes of your BP variability. Sometimes, the problem can be fixed by spreading out one’s medication into twice-a-day dosing, rather than once daily. Choosing long-acting drugs can help smooth out erratic pressures, as well. When such approaches don’t help, seeing a hypertension specialist can improve the chances of effective diagnosis and treatment. Such experts can be found in the kidney disease (nephrology) field, as well as in internal medicine and cardiology.
The causes of BP volatility are unclear, but effects of the so-called sympathetic nervous system (SNS) are probably involved. The SNS controls our “fight-or-flight” response, an adrenalin-fueled defense mechanism that can also be turned on by strong emotions or other stressors. A common condition which brings about surges in SNS activity and BP variability is obstructive sleep apnea (OSA). Your doctor could consider obtaining a polysomnogram or “sleep study,” to determine whether or not you have OSA.
Q. I’m 71 and have paroxysmal atrial fibrillation. The episodes, which started about five years ago, usually last a day or two. Will these episodes increase in duration and frequency? How long can a heart beat at that unhealthy rate before damage is done?
A. Atrial fibrillation (a-fib) is a condition in which the atria, the upper chambers of the heart, quiver uncontrollably rather than contracting in an orderly fashion. When the abnormal electrical activity of the atria passes to the ventricles (lower chambers which pump to the body), the heart tends to beat rapidly and irregularly, as you describe. Unfortunately, studies have indicated that intermittent, episodic a-fib such as yours has about a five-percent chance per year of becoming permanent. Factors which tend to increase likelihood of progression include older age, an enlarged heart, a history of heart failure, and a prior heart attack.
Regarding your other question, it usually takes at least a week of rapid a-fib to decrease cardiac pump function. Typically, such changes are reversible once normal (sinus) rhythm has been re-established. However, as doctors say, “a-fib begets a-fib,” meaning that episodes tend to cause a self-sustaining cycle, inducing longer and more frequent periods of arrhythmia. In order to decrease your risk of stroke and heart failure, your best bet is to find a cardiac electrophysiologist with whom you feel comfortable, and discuss your options. In the meantime, anticoagulation with warfarin (Coumadin) or one of the other newer drugs should be strongly considered for stroke prevention, if you are not already receiving such treatment.