Hypertension is the most common reason that patients visit their physician.¹ Hypertension affects approximately 50 million people in the United States (25% of the adult population) and nearly 1 billion people worldwide.² Hypertension is an important risk factor for stroke, myocardial infarction, heart failure, chronic kidney disease, atherosclerosis, and dementia.¹ The detrimental effects of hypertension increase continuously as the blood pressure continues to rise; there is no absolute threshold of blood pressure that distinguishes risk from safety. Reducing hypertension greatly decreases the morbidity and mortality of cardiovascular disease. Despite public and professional efforts to educate the public on the risks of hypertension and the benefits of treatment, only 70% of US adults with hypertension are aware they have the condition, only 58% are receiving treatment, and in only 31% is hypertension controlled.^1,2

Hypertension is defined as a sustained systolic pressure greater than 140 mm Hg or a sustained diastolic pressure greater than 90 mm Hg.³ Systolic blood pressure is the pressure at the peak of ventricular contraction. Diastolic blood pressure is the pressure after the left ventricle has contracted. Blood pressure typically continues to rise with age. Diastolic pressure rises into the fifth decade, where it usually will plateau. Systolic blood pressure, however, continues to rise past the seventh decade. In individuals under 50 years of age, diastolic blood pressure is the major predictor of cardiovascular disease (CVD) risk. In individuals over 60 years of age, systolic blood pressure is the major predictor of CVD risk.¹ The risk for an individual is based on the level and duration of hypertension, along with the presence of other CVD risk factors. Risk factors for hypertension include race, age, minority status, obesity, physical inactivity, diabetes mellitus, and dislipidemia.¹ Several symptoms of hypertension can be observed, including tingling of the hands and feet, occipital headache, dizziness, flushing of the face, vision changes, chest pain, weakness, buzzing in the ears, and hematuria.

Dental hygienists need to be observant and listen to their patients to pick up on any of these hypertension symptoms. Hypertension is more common in men in early and middle age, but this trend is reversed in people over 60 years of age. Hypertension is more common in African Americans at all ages. Within all races, hypertension is more common in the economically disadvantaged. This article will provide the dental hygiene practitioner an evidence-based approach to the prevention and management of hypertension as proposed by the latest report released by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC).⁴

JNC 7 Guidelines

The guidelines for the classification of hypertension have changed as researchers learn more about the effects of hypertension. The JNC released its most recent report in 2004. This report is referred to as JNC 7 and is the accepted guideline for all health professionals. The guidelines lowered the range for classifying normal blood pressure and renamed one classification: normal to prehypertension is now prehypertension. JNC 7 also combined stages 2 and 3 hypertension into a single category: stage 2 hypertension. Table 1 summarizes the JNC 7 blood pressure and dental treatment guidelines.

The guidelines classify normal blood pressure as < 120/80 mm Hg, and recommend that regular dental care can be performed. Prehypertension is classified as ranging between 120-139/80-89 mm Hg; regular dental care can be performed, but patients should be advised of their blood pressure status and encouraged to make lifestyle modifications. Stage 1 hypertension is when blood pressure ranges between 140-159/90-99 mm Hg. Regular dental care can be performed on a patient with stage 1 hypertension, but a stress-reduction protocol should be used (see box) and the patient should visit his or her physician. Stage 2 hypertension is classified as >160/100 mm Hg. If a patient falls in this category, recheck blood pressure after 5 minutes, and if it is still at stage 2 levels, only noninvasive care should be performed. If the patient's blood pressure is between 160-180/100-110 mm Hg, a stress-reduction protocol should be employed and only definitive emergency care should be performed. Patients with stage 2 hypertension should be referred to a physician for immediate follow-up. Hypertensive crisis is when blood pressure is >220/120 mm Hg. Blood pressure should be rechecked in 5 minutes. No dental treatment should be performed, routine or emergency. Analgesics and/or antibiotics can be used to manage an emergency. If there are signs of organ damage, the patient should be sent to the hospital immediately, otherwise the patient should be referred to a physician for immediate evaluation.² A stress-reduction protocol includes⁵:

• scheduling shorter, early morning appointments
• taking preoperative vital signs
• using preopertative and intraoperative sedation that produces profound anesthesia
• providing postoperative pain control
• calling the patient the evening of the procedure
• having open communication with the patient about concerns or fears about the procedure

Treatment

Because oral health care providers routinely treat patients with hypertension, it is important to understand the physiology behind hypertension and how it is treated. Blood pressure can be presented as a mathematical equation in which the blood pressure equals cardiac output multiplied by the peripheral vascular resistance. Blood pressure in the normotensive patient is controlled by the same mechanisms as the hypertensive patient, except that in the hypertensive patient, the renal blood volume control system appears to be set at a higher blood pressure.⁶ Cardiac output is affected by the rate and force of contractions of the heart. Peripheral vascular resistance is determined by blood volume, blood viscosity, and vascular tone.^1,2

In the majority of people with hypertension, the cause is unknown, a condition known as primary hypertension or essential hypertension. In about 5% to 10% of patients with hypertension, the cause is known, a condition referred to as secondary hypertension. Some possible causes of secondary hypertension include pheochromocytoma, renovascular hypertension, and Cushing's syndrome.

For patients who are prehypertensive, lifestyle modification is usually the first step to try to lower blood pressure to a normal level of <120/80 mm Hg. Recommended lifestyle modifications include:

• losing weight
• increasing activity
• reducing sodium intake
• eating a diet rich in fruits and vegetables and low in fat
• abstaining from tobacco use
• decreasing alcohol intake
• ensuring adequate potassium intake

It is important to normalize the blood pressure of prehypertensive patients because one third of coronary artery disease deaths occur in individuals in the prehypertension category.¹ Antihypertension therapies usually interfere with normal physiologic mechanisms that regulate blood pressure.⁶ The goal of treatment in the hypertensive patient is to reduce the risk of CVD morbidity and mortality by lowering the blood pressure and treating other modifiable risk factors.¹ The goal for most patients is to lower the blood pressure to <140/90 mm Hg. Patients with diabetes, renal failure, or heart failure should lower blood pressure to <130/80 mm Hg.

Medications
Several different classes of medications are used to treat hypertension: diuretics, alpha-blockers, beta-blockers, combination alpha- and beta-blockers, calcium channel blockers (CCBs), angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and centrally acting agents and nitrates. Table 2 lists common hypertensive medications, their side effects, and their dental implications.

Table 2—Hypertensive Medications5,7

There are 4 different classes of diuretics: loop, thiazide, potassium-sparing, and combination. All diuretics work on some part of the membrane transport system in the renal tubule to increase sodium and water excretion, thereby decreasing blood volume. This decrease in volume works to lower the peripheral vascular resistance. Loop diuretics work by inhibiting the sodium–potassium–chloride transport system in the thick ascending loop of Henle. Inhibiting this transport system reduces the reabsorption of sodium chloride and increases the excretion of magnesium and calcium.^1,8

Thiazide diuretics inhibit the reabsorption of sodium chloride in the distal convoluted tubule, thereby lowering blood volume and pressure. Hypercalcemia is rarely caused by thiazide diuretics. An important adverse effect of thiazide diuretics is hyponatremia. Hyponatremia is a condition of hypovolemia-induced elevation of antidiuretic hormone, increased thirst, and reduced diluting capacity of the kidney. Reducing the dosage of the drug and amount of water intake can prevent hyponatremia.^1,8

Potassium-sparing diuretics inhibit the effects of aldosterone in the collecting tubule and duct, reducing the absorption of sodium, thereby decreasing the blood volume. Potassium secretion is coupled with sodium absorption in the collecting tubule and duct. Because sodium absorption is reduced, potassium excretion also is reduced, sparing the body's potassium stores. Potassium-sparing diuretics are most useful for patients with excess aldosterone, which can be caused by primary hypersecretion of aldosterone or secondary aldosteronism resulting from congestive heart failure, cirrhosis, or nephrotic syndrome. Loop and thiazide diuretics can cause potassium wasting, which can be halted by the use of a potassium-sparing diuretic. Hyperkalemia can be encountered if a potassium-sparing diuretic is used alone.^1,8

Combination diuretics are useful for patients who are not responsive to a single agent alone. Loop diuretics combined with thiazide agents often provide diuresis when neither agent alone is effective. Salt and water reabsorption often increases in either the ascending loop of Henle or the distal convoluted tubule, when the other is inhibited. Large amounts of water can be mobilized when combining a loop and thiazide diuretic, so hemodynamics must be monitored. Also, hypokalemia is very common and often must be supplemented with potassium supplements. Combining a potassium-sparing diuretic with either a loop or thiazide diuretic is useful for treating hypokalemia caused by the loop or thiazide diuretic. Potassium-sparing agents should be avoided in patients with renal failure, who can develop serious hyperkalemia.^1,8

Alpha-blockers are an important class of antihypertensive drugs. Alpha-receptors are common in the vascular smooth muscle, and their activation causes vascular constriction and increased blood pressure. When alpha-receptors are effectively blocked, the result will be vasodilation and ensuing decrease in blood pressure. Side effects of alpha-blockers are postural hypotension and reflex tachycardia. Caution should be used when administering local anesthesia with epinephrine to patients on alpha-blockers because epinephrine reversal can occur. Alpha-blockers can reverse the effects of epinephrine and actually shorten the duration of anesthesia rather than prolong it. Vasculature has both alpha- and beta-receptors. Alpha-receptors cause vasoconstriction while beta-receptors cause vasodilation. Epinephrine has its greatest effect on alpha-receptors, but also has a lesser effect on beta 2-receptors. When the alpha-receptors are blocked, the beta 2 effect of epinephrine is revealed, causing vasodilation instead of the usual vasoconstriction caused by epinephrine.^1,8,9

Beta-blockers are a class of hypertension drugs that have been around for a long time. It is important to understand that there are 2 types of beta-receptors, beta 1 and beta 2. Beta 2-receptors are present in the heart, and their activation causes increased rate and force of contractions. Beta 2-receptors are present in the vascular and bronchial smooth muscle, and their activation causes vasodilation. Drugs that block just the beta 1-receptors are referred to as cardioselective, because they exert their effect on the heart itself. Patients with asthma or chronic obstructive pulmonary disease should not be prescribed noncardioselective beta-blockers because of the bronchioconstriction they can cause. Care also must be taken to avoid a hypertensive episode from a reaction with epinephrine in local anesthesia. Noncardioselective beta-blockers can potentiate the effects of epinephrine causing a hypertensive episode or bradycardia. There are also combination alpha- and beta-blockers available. With combination alpha- and beta-blockers, fewer side effects, such as tachycardia are experienced.^1,8

Another class of drugs used to treat hypertension is CCBs. An influx of calcium is required any time the smooth muscles of the vasculature contract. By effectively blocking the influx of calcium in vascular smooth muscle, vasoconstriction can be reduced and blood pressure lowered. CCBs also have the added benefit of antianginal and antiarrhythmic effects.^1,8

ACE inhibitors are another class of drugs used to treat hypertension. They act in the renin–angiotensin cascade. Angiotensin I is turned into angiotensin II by angiotensin-converting enzyme. The production of angiotensin II causes vasoconstriction and secretion of aldosterone, with ensuing increase of sodium and water retention. The vasoconstriction and increase in water retention cause an increase in blood pressure. ACE inhibitors effectively block the action of angiotensin-converting enzyme, reducing the production of angiotensin II, thereby lowering blood pressure. ACE inhibitors also work by activating the bradykinin pathway, which causes vasodilation and a decrease in blood pressure. An adverse effect of ACE inhibitors is that the activation of the bradykinin pathway can cause a dry cough in many patients.^1,8

ARBs are a relatively new class of antihypertensive medication. These drugs block the angiotensin I receptor and effectively reduce the production of angiotensin II. The result is vasodilation and a decrease in water volume, resulting in lower blood pressure. ARBs do not activate the bradykinin pathway, so they don't cause the dry cough often associated with ACE inhibitors.^1,8

One more class of drugs used to treat hypertension is centrally acting antihypertensives. These drugs reduce the sympathetic outflow from the vasopressor centers in the brain, effectively reducing peripheral resistance and heart rate.^1,8

Treatment Plans
There is no perfect treatment regimen for hypertension. Some patients respond better to specific drugs, and not all classes of drugs work the same on all individuals. For example, many studies have shown that patients over 55 years of age and African Americans respond better to diuretics and CCBs.⁷ People under 40 years of age and whites tend to respond better to beta-blockers, ACE inhibitors, and ARBs.⁵ Compliance is a major problem preventing the effective treatment of hypertension. With that in mind, once-a-day dosing is preferred. Cost, side effects, and lack of education also contribute to patient noncompliance with medication.

After lifestyle modifications, diuretics often are considered the first line of treatment. Diuretics are inexpensive and produce limited side effects. However, most patients with hypertension require more than one medication to effectively control their blood pressure.⁷ There are 2 ways to approach multiple medication treatment. If one medication is tried without reaching the desired goals, an additional drug from a different class can be added. Combination therapy has become increasingly popular as well.¹⁰ This is when drugs from 2 different classes are combined into one dose. Usually a combination drug consists of a thiazide diuretic combined with an ACE inhibitor, an ARB, or a beta-blocker. An important advantage of combination therapy is the ease of use for the patient. Most patients are more likely to take just one pill than multiple pills.¹¹ JNC 7 recommends initial combination therapy for patients whose blood pressure is more than 20/10 mm Hg above their target blood pressure.¹²

Hypertension is twice as common in patients with type 2 diabetes. These patients require an aggressive treatment goal of attaining blood pressure < 130/80 mm Hg.¹³ Kastarinen and colleagues showed that ACE inhibitors and ARBs are more effective in treating hypertension in patients with diabetes.¹⁴ The prevalence of hypertension increases with age, most likely because arterial compliance decreases with age. Studies have shown that in elderly patients without any concomitant conditions, a diuretic is the most effective and has the fewest side effects.¹⁵ Patients with a history of myocardial infarction or angina should begin treatment with an ACE inhibitor and a beta-blocker.⁷

Dental Hygienists' Role

Most patients see their oral care professional more frequently than their physician. This gives hygienists more opportunities to monitor their patients' blood pressure and detect rising blood pressure in its earlier stages. Because roughly one third of patients with hypertension are unaware that they have hypertension, dental hygienists play an important role by continuing to monitor their patients' blood pressure.¹² Hygienists also can recognize the noncompliant hypertensive patient. If noncompliance is suspected, patients should be encouraged to see their physicians and reminded of the potential risks and complications associated with hypertension.

Oral Care Implications
With patients whose hypertension is controlled, there are several treatment considerations. The most important action an oral health care professional can take to avoid blood pressure elevation in these patients is to provide effective operative and postoperative pain control.¹⁶ Stress and anxiety can cause blood pressure to increase, so a stress-reduction protocol should be used. Preoperative sedation, such as diazepam, and operative nitrous oxide can be used to minimize stress.

Proper administration of local anesthetic is a very important issue when treating all hypertensive patients. Epinephrine, a component in many local anesthetics, can antagonize the antihypertensive effects of all hypertension medications except alpha-blockers, beta-blockers, and combined alpha- and beta-blockers.² This antagonism can lead to an increase in blood pressure, angina, or a potential hypertensive crisis. Patients taking alpha-blockers can experience epinephrine reversal, which is a decrease in the duration of anesthesia caused by the unmasking of epinephrine-induced vasodilation (blood vessels in the body become wider following the relaxation of the smooth muscle in the vessel wall).¹⁶ Epinephrine also can cause tachycardia and postural hypertension; therefore, it should not be administered to patients taking alpha-blockers. The recommended maximum amount of epinephrine that can be administered to cardiac risk patients is 0.04 mg, which equates to 2 cartridges of lidocaine 2% with 1:100,000 epinephrine. Proper technique, with aspiration and slow injection, can help prevent complications.²

There are several side effects associated with medications used for hypertension. One of the most notable is gingival hyperplasia, caused by CCBs. If gingival hyperplasia is encountered in a patient on CCBs, oral hygiene should be stressed, the patient placed on a more frequent recall schedule, and caries and defective restorations should be restored. If this does not alleviate the situation, the patient's physician should be consulted to see if another class of drugs can be considered. As a last resort, gingivectomy can be performed.¹⁷ Many antihypertensive medications also can cause dry mouth, with clonidine being the most severe.¹⁸ Patients experiencing xerostomia should be placed on more frequent recall schedules, have diet counseling to reduce sugar intake and meal frequency, increase salivation with sugar-free drops, use mouth moisturizers and, in severe cases, be prescribed pilocarpine.¹

Many antihypertensive medications have interactions with nonsteroidal anti-inflammatory drugs (NSAIDs). The exact mechanism of this effect is not clear, but the NSAID-induced inhibition of prostaglandins is the most likely cause because prostaglandins cause vasodilation.^19,20 NSAIDs also interfere with ACE-inhibitor deactivation of bradykinin, lessening the antihypertensive effect of ACE inhibitors.²¹

Conclusion

Dental hygienists must routinely check their patients' blood pressure to screen for hypertension and to assess each patient's eligibility to undergo his or her scheduled procedure. Lifestyle modifications should be encouraged and a visit to the patient's physician recommended if blood pressure is >140/90 mm Hg. Noninvasive care should not be performed if blood pressure is >160/90 mm Hg. When treating the hypertensive patient, a stress protocol should be actively pursued. Epinephrine should be limited to 2 cartridges of lidocaine 2% with 1:100,000 epinephrine for the patient who has CVD. Side effects of antihypertensive medications, such as xerostomia and gingival hyperplasia, should be managed accordingly. Profound anesthesia is paramount when treating the hypertensive patient. This can be achieved with sound technique, aspiration, and slow injection. Treating the patient on hypertensive medications is a routine part of dentistry, but guidelines and good judgment must be strictly followed.

References

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17. Rhoades R, Pflanzer R. Human Physiology. Philadelphia, Pa: WB Saunders; 1996:342-361.
18. Williams L. JNC 7 urges aggressive management of hypertension. J Hypertens. 2003;21:3-10.
19. Berne RM, Levy MN. Cardiovascular Physiology. 7th ed. St. Louis, Mo: Mosby; 1997:67-103
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	Kishore Shetty, DDS, MS, MRCS Dr. Shetty is associate professor in the department of restorative dentistry at the University of Texas Dental Branch at Houston, where he also serves as director of the Medically Complex Patient Clinic. He is a diplomate of the Royal College of Surgeons, England, and the American Board of Special Care Dentistry.
	Mark Lukin, DDS Dr. Mark Lukin is a graduate of the University of Texas at Houston Dental Branch and practices general dentistry in Sugar Land, Texas.