Hypertension, or high blood pressure, is one of the commonest ailments. It affects one in four of us, yet in only 5 per cent of cases is a cause fully established. The remaining 95 per cent are labelled "essential hypertension", which is not a particularly helpful term to describe a condition with a probable multiplicity of causes. "Primary hypertension" might have been a better phrase.
A medical colleague has kindly sent me a copy of 100 Questions And Answers About Hypertension by two blood-pressure experts from the United States. The book is driven by the questions Drs William Manger and Ray Gifford are most commonly asked by their patients.
"What is essential hypertension?" was the first to catch my eye. "This term is a misnomer because primary hypertension is not essential for anything!", is the crisp opening answer. "The condition is probably the result of multiple factors," the authors continue, referring to heredity, environmental factors and personal factors such as sensitivity to salt, being overweight, drinking excessive amounts of alcohol and following a sedentary lifestyle.
"Which blood pressure is more important - systolic or diastolic?" is a question asked by many people with hypertension. For many years, doctors concentrated on diastolic measurement - the lower of the two blood-pressure figures - when treating patients.
But as the authors point out, "observational studies have confirmed that systolic blood pressure is actually a better predictor of strokes, heart attacks, heart failure, kidney disease and overall mortality".
One of the annoying things about high blood pressure from a patient's perspective is that the condition is symptomless. Blood pressure has to reach really high levels before headaches or blurred vision manifest themselves. Human nature being what it is, there is a natural reluctance to take ongoing medication for a condition that does not bother you with symptoms.
And so another question - "once I start taking medicine for high blood pressure, do I have to take it for ever?" - is also common. In their reply, the authors say hypertension is analogous to diabetes.
"Patients with diabetes must take pills or insulin to maintain their blood sugar in a normal range, but the therapy does not cure the diabetes. Similarly, medication controls hypertension only so long as you take the drugs."
Food and diet are important elements in the non-pharmacological control of hypertension. Question 88 asks: "What foods or drinks should I avoid if I have hypertension?" If you are salt-sensitive - and Manger and Gifford says 50-60 per cent of those with primary hypertension are - then you must watch your intake. They recommend no more than six grams of salt per day and point out that many processed foods have a high salt content.
"Men with hypertension should limit [their alcohol] intake to no more than two glasses of wine per day, and women with hypertension should limit alcohol consumption to only one drink daily," they say.
In a rare departure from scientific reasoning, the authors admit they are proponents of vitamin E as an antioxidant reputed to reduce damage to arteries and so help prevent coronary heart disease. They are believers in vitamin E supplementation. "We take 400 international units of vitamin E daily, even though its therapeutic value has not been established," they tell readers.
I learnt a lot from a question on the importance of potassium in the management of hypertension. A mineral similar to sodium, potassium replaces and eliminates excess sodium from body tissues, which helps to reduce blood pressure in salt-sensitive people. It also dilates blood vessels, indirectly reducing hypertension.
Manger and Gifford emphasise the importance of the DASH - dietary approaches to stop hypertension - diet. It contains lots of fruit and vegetables, which are rich sources of potassium, and is low in fat. The diet's ability to reduce both systolic and diastolic hypertension has now been scientifically proven.
Proponents of complementary medicine will be disappointed with the answer to: "are alternative remedies helpful in hypertension?" "There is no convincing evidence that alternative medicine can control hypertension," they say, firmly.
They also discuss the effect of hypertension on a person's sex life. "Diuretics [water tablets] and beta blockers may rarely be responsible for sexual dysfunction in men."
Viagra "can be used in patients with hypertension that is adequately controlled with medication or lifestyle changes."
This is a useful book for anyone with elevated blood pressure. Although written for an American audience, it will not irritate a European reader.
100 Questions And Answers About Hypertension is published by Blackwell Science, £12.95 in UK
You can e-mail Dr Muiris Houston, Medical Correspondent, at mhouston@irish-times.ie or leave a message on 01-6707711, ext 8511. He regrets he cannot reply to individual medical problems
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