Cultural Competence: Cardiovascular Medications

Elizabeth Connelly Kudzma, DNSc, MPH, RNC

Disclosures

Prog Cardiovasc Nurs. 2001;16(4) 

In This Article

Hypertension in Black Patients

Hypertension is a serious issue in black populations because this group has the highest incidence of hypertensive morbidity and comorbid conditions (greater risk of stroke and heart and renal disease). Using the drug hydrochlorothiazide, Freis[13] reported that 67% of younger (<55 years) black patients and 80% of older (55-65 years) black patients achieved blood pressure control (diastolic blood pressure of <90 mm Hg). In 1993, Materson et al.[8] reported the similar finding that 40% of younger and 58% of older blacks achieved blood pressure control using hydrochlorothiazide as a single agent. Studies like these supported the position of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC V), which advised low doses of a thiazide diuretic (12.5-25 mg hydrochlorothiazide) as the agent of first choice for hypertensive black patients. JNC VI[14,15] currently advises that diuretics be used for initial therapy unless there are contraindications or coexisting conditions that might be treated by another agent. In the presence of renal disease, a loop diuretic should be used, as thiazide diuretics become less effective.[16] JNC VI also allows for initial therapy with ß blockers. However, ß blockers as first-line therapy have been shown to be less predictable than diuretics in black patients; labetalol, a combined blocker, might be recommended as equally effective in both black and Caucasian populations.[17,18]

Recent studies of antihypertensive agent efficacy in black and white comparison populations have sought to determine whether differences in salt sensitivity and renin levels could further explain noted racial differences in drug response. A number of studies have suggested that black patients tend toward low-renin profiles, while white patients tend toward moderate to high renin levels. Weir et al.[10] investigated the influence of dietary salt on antihypertensive medication effectiveness and concluded that treatment with both enalapril (Vasotec®) and isradipine (Dynacirc®) lowered blood pressure in the presence of high salt intake, but that greater blood pressure control was achieved overall in all racial populations on a low-salt diet. On the high-salt diet, blacks had better blood pressure control with isradipine. Preston et al.[11] investigated the influence of plasma renin levels on the patient's response to antihypertensive agents. In this study, age and race more significantly predicted response to the antihypertensive agent than the renin profile, and clonidine (Catapres®) and diltiazem (Cardizem®) were the most effective agents overall, independent of renin levels. Bakris et al.[19] investigated the use of antihypertensive agents in black Americans with diabetic nephropathy. An antihypertensive agent (verapamil) that reduced arterial pressure and proteinuria slowed the progression of diabetic renal disease to a greater extent than an agent (atenolol) without that effect.

Studies of hypertensive pathophysiology in black patients indicate that low renin levels, salt sensitivity, and impaired salt excretion are more prevalent. Obesity is more prevalent in black women as compared to other black or white adults, and dietary intake of potassium is often lower in blacks as compared to whites.[16] These facts suggest that lifestyle modifications might be the most effective strategy to lower blood pressure in this population. Reductions in body weight of as little as 7 lb and use of oral potassium supplements can significantly reduce blood pressure.[16] A high proportion of this group is overweight and has a higher-than-reported intake of sodium, which is unknown to both the patient and health care provider. For these patients precise dietary counseling and monitoring are indicated. Part of the increased risk for hypertension and cardiovascular disease in black Americans may be mediated through differing vascular responses. Wood[20] indicated that black Americans have an impaired vascular response to the ß receptor drug isoproterenol (Isuprel®) and an impairment of vasodilation in response to nitric oxide-mediated drugs (nitrates).

Calcium channel blockers are also an excellent choice for black patients[8] with salt sensitivity, especially those who are not responsive to diuretics. Treatment with diltiazem produced the best blood pressure control for black patients in a study of six classes of agents, with a 64% rate of response.[8] For black patients who cannot take hydrochlorothiazide or calcium channel blockers, other antihypertensive classes -- specifically, angiotensin-converting enzyme (ACE) inhibitors and ß blockers -- may be useful to lower blood pressure even though studies indicate that these agents may not be quite as effective. If a diuretic is combined with an ACE inhibitor or ß blocker as primary or secondary therapy, the two together produce similar lowering of blood pressure,[21] probably due to better stimulation of renin secretion.

JNC VI also provides support for use of antihypertensive medication choices in the presence of known coexisting conditions. Minority patients who have coexisting conditions are especially at risk for undertreatment. Beta blockers are specifically indicated for patients who have a history of myocardial infarction and ACE inhibitors are recommended for patients with an ejection fraction of <40% (heart failure) and diabetes with proteinuria. Most hypertensive black patients will need two or more medications to attain adequate blood pressure control, as only 46% of black patients achieved a diastolic blood pressure <90 mm Hg on one antihypertensive medication.[8] More attention should be given to black patients with a history of myocardial infarction, who should receive a ß blocker, and those with heart failure or diabetic nephropathy, who should take an ACE inhibitor. These drugs may protect the patient by more mechanisms than solely lowering blood pressure. Bakris et al.[19] reported that in diabetic black hypertensive patients with demonstrated nephropathy, drug treatment that reduced arterial pressure and proteinuria also appeared to slow the progression of renal disease. Table III summarizes therapeutic nursing considerations for black hypertensive patients.

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