SYSTEMIC CONDITIONS
Is There a Hypertensive in the House?
An O.D.'s primer on systemic hypertension.
By Deepak Gupta, O.D., F.A.A.O. and Sonia K. Gupta, Rp.H., M.S.

Experts estimate that roughly one in four adults in this country suffers from hypertension. Many refer to the condition as the "silent killer" because patients usually don't notice any symptoms before major damage occurs to organ systems. Healthcare professionals have associated untreated hypertension with health problems such as stroke, myocardial infarction, renal failure, congestive heart failure and progressive atherosclerosis.

Because optometrists are usually one of the most accessible healthcare providers, we have a great opportunity to work closely with other members of the healthcare team in services ranging from initial blood pressure screenings to collaborative efforts with the primary care physician. Regardless of our level of intervention, we should all have a working knowledge of systemic hypertension and its treatment.

Do you know the basics?

Your blood pressure measurement consists of systolic and diastolic numbers. The systolic measurement (the top number), represents the pressure of blood against the artery walls when the heart has just finished pumping (contracting). The diastolic measurement (the bottom number), is the pressure of blood against the artery walls between heartbeats, when the heart is relaxed and filling with blood.

The classic definition of normal blood pressure was 120/80 mmHg, but recent years have seen a new classification scheme. Millions of people whose blood pressure was previously considered borderline high (130 to 139 mmHg/ 85 to 89 mmHg) or normal (120/80) now fall into the "prehypertension" range based on new, more aggressive high blood pressure guidelines, listed in the box below.

Evaluation and diagnosis

Proper diagnosis and management of a patient suspected of having hypertension includes both physical and laboratory tests. The lab tests usually include a 12-lead electrocardiogram, urinalysis, complete blood count, blood chemistries (potassium, sodium, creatinine, fasting glucose and lipid profile) and calcium. Doctors take this combination approach to help assess cardiovascular risk factors that affect prognosis and treatment. They also help reveal potentially identifiable causes of the hypertension and help identify any signs of target-organ damage.

Because many variables can impact blood pressure, don't base your diagnosis of hypertension on an isolated reading. Instead, verify elevated blood pressures on multiple occasions over time. Obviously, one of the most important factors in this process is the accuracy of the measurement; even seemingly trivial errors in measurement can potentially misclassify a patient.

Beating the problem

As is the case with glaucoma and IOP, the trend in managing hypertension in the past several years has been for more stringent control and more lowering of blood pressure. Management strategies focus on an individual approach that includes the influence of the additional co-morbidities on the selection of proper anti-hypertensive therapy, but also an appreciation for cultural and sociodemographic factors that can impact the success of treatment.

Most patients who have hypertension will be unable to maintain proper blood pressure control with a single agent. Rather than increase the dose of one anti-hypertensive agent to the maximum recommended dosage, it's preferable to use two or more drugs with complementary mechanisms of action at lower doses. Doing so lowers blood pressure without dramatically increasing the risk for adverse effects. The following section outlines a list of currently available anti-hypertensive agents and their drug classes.

ACE inhibitors. Angiotensin-converting enzyme (ACE) inhibitors block an enzyme that's involved in constriction of the blood vessels. As a result, blood vessels relax and widen, making it easier for blood to flow through the vessels. This, in turn, lowers blood pressure. These medications also mildly increase the release of water and sodium to the urine, which also helps lower blood pressure. ACE inhibitors are a good choice for diabetic patients because they don't affect blood sugar levels and may help protect the kidneys.

Calcium-channel blockers. These medications work by reducing the amount of constriction of the blood vessels, making it easier for blood to flow through the vessels and lowering blood pressure. Calcium-channel blockers are especially effective in older adults, African Americans and individuals who have a difficult time reducing their sodium intake.

Angiotensin II receptor blockers (ARBs). These agents block the action of a hormone that causes vasoconstriction. As a result, blood vessels dilate, making it easier for blood to flow, thus reducing blood pressure. These drugs also increase the release of sodium and water into the urine, which also lowers blood pressure.

Diuretics. These cause the kidneys to remove sodium and water from the body, which helps to relax the blood vessel walls, thereby lowering blood pressure. The most popular drug in this category is hydrochlorothiazide. This drug class is divided into loop diuretics and potassium-sparing.

• Loop diuretics increase urine output quickly for a few hours.
• Potassium-sparing diuretics, unlike most other diuretics, don't cause potassium levels to drop.

Diuretics are usually recommended as one of at least two medications to control high blood pressure. Diuretics are especially beneficial in older adults, African American patients, people who are overweight and people who have heart failure.

A recent landmark study (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial, or ALLHAT) shows that diuretics are the most effective medication for lowering blood pressure and preventing heart disease and stroke in older adults. The study compared a diuretic to an ACE inhibitor and a calcium-channel blocker. Results showed that diuretics are equally as effective as ACE inhibitors and calcium-channel blockers in preventing fatal and nonfatal heart attacks.

Beta blockers. Beta blockers lower blood pressure by decreasing heart rate and the amount of blood the heart pumps out with each beat, and they relax the blood vessels.

In addition to medical therapy, encourage hypertensive patients to make certain lifestyle changes, even if they aren't on medical therapy at the time. Specifically, encourage patients to start a regular exercise program and to make certain dietary changes.

An ideal diet consists of fruits, vegetables and low-fat dietary products with a reduced amount of saturated and total fat (known as the DASH diet). In some patients, these dietary changes, along with a regular exercise program, have demonstrated equal blood pressure lowering effects similar to single-drug therapy.

What next?

As you might expect, hypertensive patients require frequent monitoring of their blood pressure to make sure that it's well controlled. These follow-up visits provide us with an opportunity to assess anti-hypertensive efficacy and to make sure that patients aren't experiencing adverse reactions.

In patients whose blood pressure isn't controlled, the general recommendation is usually monthly follow ups until they achieve control. Once blood pressure is stable, follow up can occur at three- to six-month intervals.

References available on request.

Dr. Gupta practices full scope optometry in Stamford, Conn. He's also clinical director of The Center for Keratoconus at Stamford Ophthalmology. Reach him by e-mail him at Deegup4919@hotmail.com.

Ms. Gupta is a clinical pharmacist with years of both retail and hospital pharmacy experience.