September 12, 2014

Blood Pressure Fluctuations = Increased Stroke Risk

A few days ago, I had dinner with my kids. Among other things, we discussed my current problem with blood pressure (bp): most days, my systolic (upper) numbers typically range from under 100 to over 200. We all agreed these wild fluctuations can't be good.

The next morning, my son sent me an email with a link to a report with this headline:
High blood pressure: New research suggests that see-sawing readings are the key danger sign for strokes.
Needless to say, that got my attention! I immediately opened on the link.

The report is based on work by Professor Peter Rothwell, director of the Oxford Stroke Prevention Research Unit in England.

What Matters are the Blood Pressure Variations
For years, experts thought consistently high bp created the greatest stroke risk. But evidence now suggests the real risk is more a function of dramatic blood pressure variations from hour to hour, day to day, week to week.

Nonetheless, many patients still hear their internists say their blood pressure is acceptable, when in fact their bp may be spiking dangerously from stress or exertion . . . or in my case, from either Parkinson’s disease or the medicine I take for. Doctors haven't seemed unduly worried by those highs and lows, as long as the average numbers fell inside some acceptable middle ground.

Risk of Using Averages of Blood Pressure Readings
Blood pressure fluctuation is very common. Research suggests it's most common in women, diabetics, and people over 60.

Professor Rothwell has demonstrated that -- far from being something to ignore -- bp fluctuation is closely linked to stroke. Based on statistics from major trials on thousands of stroke patients, Rothwell concluded that blood pressure variations predict stroke far more reliably than blood pressure averages.

Sustained high blood pressure might gradually weaken blood vessels and cause them to become rigid. But the new evidence suggests that sudden bp surges create the stroke risk, particularly as we get older. A 2003 pan-European study of 774 people with hypertension reported that nighttime blood pressure variability was a clear risk factor for stroke in older people.

The medical journal The Lancet suggested that Professor Rothwell's conclusions have changed “the landscape of stroke prevention.”

Enter Calcium Channel Blockers
Treating bp variations is extremely challenging, because prescribing medicines to lower the numbers can result in dizziness and falls, while doing nothing raises risk of heart attack and stroke. But Professor Rothwell has evidence that stroke risk can be reduced if doctors could simply -- and sooner -- identify patients with dangerous levels of bp variability and then treat them with calcium channel blockers.

A large 2005 Anglo-Scandinavian trial of bp treatments reported that these calcium channel blockers more effectively prevented strokes than commonly used beta blockers. Rothwell explained that calcium channel blockers raise the troughs and lower the peaks in bp fluctuations -- effectively ironing out extremes. He also found that other drugs, like beta blockers, actually exacerbate the variations, even though the final "average" numbers may appear to be lower. 

Calcium channel blockers widen blood vessels. They're among the four most commonly prescribed hypertension drugs. The others are ACE inhibitors (which also widen blood vessels), diuretics (which remove water from the body), and beta-blockers (which slow the heart).

Calcium channel blockers have not usually been the first choice for  bp treatment. Although new UK guidelines recommend these blockers for people over 55, the guidelines don’t specify their use to treat the issue of  bp variability -- Rothwell's big concern. He thinks the research results are clear, and that doctors now need to be educated -- and convinced -- to use calcium channel blockers.

What To Watch For
I’ve used a wrist monitor to check my bp for several years. My internist’s nurse has checked  it for accuracy. Here’s what Rothwell's report suggests:
  •  Look at the systolic (upper) number. It is not unusual for this to vary by up to 60 from one hour to next during the day. This is normally nothing to worry about.
  •  It’s also normal for readings taken once a day or once a week (at the same time) to vary by about 20.
  • However, with variable blood pressure, the readings taken once a day or once a week are likely to vary by 50 or more. People with variable blood pressure show wide fluctuations daily, weekly, and monthly.
My Readings Are Cause for Concern
I’ve been recording my erratic bp numbers for at least a year. While Rothwell suggests that stress and relaxation cause fluctuations, I’m convinced that my sharp variations are a function of my Parkinson’s disease and/or the carbidopa/levodopa medicine I take for it.

I’ve been dealing with two separate issues:

1) Spikes in blood pressure that coincide with the wearing off of my carbidopa/levadopa medication. Before a new pill kicks in, my systolic reading can hit 200 or above. The only solution -- based on my present meds -- is to take another pill. As a result, the new, shrinking interval between pills is about three hours. The new schedule results in seven or eight "swings" a day. For example, my numbers this morning:
  • 7:00 -- 189/113 (then I took two 25/100 pills)
  • 7:15 -- 175/99
  • 7:30 -- 145/94 
This is the regular pattern as old pills wear off and new pills kick in.
2) Drops in blood pressure when that top number falls below 100. During these times, I feel faint, sometimes like I might even pass out. Those symptoms resemble the effects of orthostatic hypotension, low bp that typically occurs when someone rises from a chair. But that's not what causes my wooziness. Instead, I experience the sudden bp drops when I'm outside in hot, humid weather... although the scary symptoms have occurred at other times, too.

So, What Do I Do?
A good question, and I don't have an answer. But I've begun some interesting talks with my neurologist and blood pressure specialist. Stay tuned.


sherryocala said...

Hi, John, I'm so glad to have found your blog tonight since my husband (age 78) also has very erratic bp's. His dose of c/l is presently 50/200 of the CR (continuous release) version of sinemet. He takes it every 3 hours during waking hours. Generally, he does not have off times, but his low BP times cause similar disability, usually in mornings. I would like to communicate further with you since there are many similarities between you, but right now we have to go to bed. :) Take care!

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