INTRODUCTION
Hypertension is a worldwide concern which can be attributed to approximately 7.1 million deaths per year and has a prevalence of approximately 1 billion.1 In 2007, 5.7 million Canadians were diagnosed with hypertension and more than 5 million of them were using pharmacotherapy to treat their hypertension.2 The goal of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC7) is to issue guidelines for the prevention and management of hypertension. Past guidelines have been met with considerable success as the awareness for hypertension has increased dramatically from 51% in 1976-1980 to 70% in 1999-2000.3 This awareness has resulted in more people seeking treatment for hypertension and as a result by 1991 the mean systolic blood pressure (SBP) for individuals 60-70 years old was 16 mmHg lower when compared with the equivalent group in 1960. The changes in hypertension prevalence have been reflected in the decreased morbidity and mortality associated with hypertension. Specifically, the age-adjusted death rates from stroke and coronary heart disease have declined by 60% and 50% since 1972 respectively. However, the success cannot be applied to the total population as current control rates for hypertension in the United States is still quite poor and 30% unawareness is still unacceptably high. Additionally, greater than 40% of the patients with hypertension are not treated and a further two-thirds of the treated patients have not met their target values (BP < 140/90 mmHg). While the reductions in congestive heart failure (CHD) and stroke associated deaths have declined, the rate of decline is slowing down. Hypertension is secondary to only diabetes in end-stage renal disease and therefore continues to be an enormous burden on the health care system and is estimated to consume 10% of health care costs in developed countries such as Canada.4 As dentists, we have the unique opportunity to increase awareness, help identify and refer patients in whom hypertension may be present or poorly controlled.
PREVENTION
If the rise in blood pressure can be prevented, the concurrent risk of congestive heart failure and stroke would be decreased. Fortunately, the important causal factors associated with hypertension have been identified and are readily preventable. Excess body weight, high dietary sodium, lack of physical exercise, inadequate intake of fruits and vegetables, potassium and excess alcohol consumption are several of these factors.3 There are numerous political, economical and social barriers to prevention and understandably overcoming these barriers is a challenge, however, the benefits of such changes are substantial as just a 5 mmHg reduction in SBP would translate to an estimated 14% reduction in stroke and 9% reduction in CHD.
DETECTION
Prior to describing proper hypertension detection it is important to review the current definitions of hypertension as these have undergone subtle but important changes since the JNC6. The important differences are highlighted in Table 1. Briefly, the normal value of blood pressure has changed to “less than 120/80”, which is a departure from the classical designation of 120/80, which is now regarded as Prehypertension. It is important to realize that Prehypertension is not a disease category but rather a designation that serves as a marker for identifying patients at high risk of future development of hypertension. The previous normal and borderline categories have been amalgamated to Prehypertension; Stage 2 and 3 of Hypertension have also been combined into a single stage.
Detection of hypertension in the office requires blood pressure measuring equipment that is inspected and ideally validated. Additionally, the user must be regularly trained in a standardized measurement technique to ensure consistency and accuracy. The preferred method is auscultation, with the patient seated quietly for at least 5 minutes with feet on the floor and arm at the level of the heart, rather than lying down on a table. To help avoid artificially high readings, caffeine, exercise and smoking should be avoided at least 30 minutes prior to measuring. It is important have a proper size BP cuff by ensuring at least 80% of the cuff bladder encircles the patients arm. Two measurements should be recorded and the average taken. The first step is manual palpation of the radial artery and inflation of the cuff pressure until the radial pulse cannot be palpated. The blood pressure cuff is then deflated in slow 2 mmHg/s increments and the pressure at which palpation of the radial pulse is resumed, is the estimated systolic blood pressure. With a stethoscope placed in the antecubital fossa, the cuff pressure is increased 20-30 mmHg mercury above the level of the estimated systolic blood pressure and again decreased at a rate of 2 mmHg/s while listening for the beginning and ending of the Korotkoff sounds which signify the systolic and diastolic blood pressure, respectively.5
EVALUTION
Patients with detected hypertension (SBP > 140 mmHg and DBP > 90 mmHg) should be referred to the primary care physician for further evaluation. Thereafter, it is important that blood pressure is assessed to rule out “white coat syndrome”, as well as underlying causes, and to assess for possible organ damage. Patients with “white coat hypertension” have an elevated office BP and normal BP when monitored at home. This is often related to the elevated anxiety levels that some patients feel when visiting the dental office. Its prevalence has been reported to be 12% to 18 % the general population.6 Recently, several investigations have demonstrated that regular measuring of blood pressure at home is superior at predicting cardiovascular risk than office BP. Based on these data, the American Heart Association (AHA) and American Society of Hypertension (ASH) have developed and endorsed home BP monitoring guidelines which recommend that an accurately calibrated device be used to measure BP at home before the appointment with the physician, with at least two morning and two evening readings every day for one week.7
Baseline tests such as an electrocardiogram, urinalysis, blood glucose, complete blood count, electrolytes, creatinine, as well as a lipid profile are recommended by JNC7 to assess etiology, progression, effects, and other existing co-morbidities of this condition. For example, increased serum creatinine and hypertension may provide clues about renal disease, whereas low serum potassium and hypertension may be caused by Cushing’s syndrome.
TREATMENT
With every new set of guidelines set by the Joint National Committee, there is an increasing recognition that the threshold for treatment of hypertension and the drug therapy used should not be based solely on the stage of hypertension but also in terms of their total cardiovascular risk, coexistence of other risk factors and comorbidities, and accumulated organ damage (Table 2).
Lifestyle modifications are important non-pharmacologic interventions for effective control of blood pressure and also reducing cardiovascular risk (Table 3). These modifications include increasing physical activity, reducing salt intake to less than 6 g per day, and limiting alcohol intake. Cook and colleagues conducted a large-scale trial in 2007 which studied the long term follow-up of hypertensive patients showed that a low sodium diet had a 25% risk reduction in future cardiovascular events.8
Patients whose blood pressures are above target should be monitored at least every 2 months. Follow-up at short intervals improves patient adherence and is required to increase the intensity of treatment.
Adherence to prescribed lifestyle changes and pharmacotherapy should be assessed at each visit to the primary care physician, but also can be gauged at the dental office as well.
Based on the results of recent clinical outcome data, p
harmacologic treatment of hypertension has been shown to reduce the complications of this condition using several classes of medication. Thiazide diuretics have been the basis of therapy in most clinical trials and have been shown to be most effective especially in preventing the cardiovascular complications. Thus, the JNC7 recommends diuretics as first-line therapy for management of stage 1 Hypertension, while a combination of two drugs are recommended as initial therapy of stage 2 Hypertension, one of which should be a diuretic.
SIGNIFICANCE FOR THE DENTIST
One-third of people with clinical hypertension are undiagnosed.9 Furthermore, only one-third of these patients are being treated according to the guidelines of JNC7. It is important that dentists be aware that a significant portion of their patients may have undiagnosed or poorly controlled hypertension. Additionally, with poorly controlled hypertension, the risk for a significant cardiovascular event is compounded by procedural stress or epinephrine exposure from local anesthetic or other exogenous sources. Table 4 provides a reasonable guideline for management of a patient whose blood pressure is measured to be elevated during a visit.
While studies regarding the cardiovascular effects of epinephrine on dental patients are quite dated, most have concluded that the use of epinephrine in local anesthetics has not resulted in significant morbidity or mortality. However, it is widely recommended that epinephrine-containing local anesthetics should be limited to one to three cartridges of 2 percent lidocaine with 1:100,000 epinephrine or its equivalent.10 Furthermore, the use of epinephrine- or vasopressin-impregnated retraction cords should be avoided, as there are sufficient alternatives available for hemostasis.12
CONCLUSION
Hypertension-associated morbidity and mortality is a major heath concern, however with appropriate treatment, hypertension can be managed and the associated sequelae, reduced. The key to controlling this disease depends on proper and timely, prevention, detection, evaluation and treatment. As dental health professionals, we should take an active interest in our patients’ general health and use our routine encounters to help further their general well-being. OH
Dr. Sepehr Zahedi is a senior resident in discipline of Dental Anaesthesia at the University of Toronto and maintains a general practice on weekends.
Dr. Robert Marciniak is a U of Toronto Dental Anaesthesia resident, Yr3; UBC Dentistry 2006 (DMD).
Oral Health welcomes this original article.
REFERENCES
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8. Cook NR, Cutler JA, Obarzanek E, et al: Long term effects of dietary sodium reduction on cardiovascular disease outcomes: Observational follow-up of the trials of hypertension prevention (TOHP). BMJ. 2007, 334: (7599): 885
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10. Yagiela JA., Haymore TL, CDA Journal. 35 (1), 2007
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