Essential Hypertension

Essential Hypertension


Here is a talk on essential hypertension. And it’s a broad topic. But I’m going to try and cram it into 10 minutes and give you most information that you’ll need to know. My name is John Roberts, MD. I’m currently a resident at Duke University in the Internal Medicine Residency Program. So let’s get moving. And here are the learning objectives for this talk. Number one, I want to recall the definition of hypertension. I want you to learn the general approach to a patient with newly diagnosed hypertension. I also want you to understand the benefits of treatment. And I want you to understand the general approach to antihypertensive therapy. Our outline. First, the definition of hypertension. Then we’ll go through the mechanisms of disease. Next, I’ll talk about the approach to the hypertensive patient. Next, treatment goals, and then outpatient management. First of all, it’s important to note that the Joint National Committee, or the JNC, is a group of hypertension experts who were commissioned by the National Institutes of Health to produce guidelines on the prevention, detection, evaluation, and treatment of high blood pressure. This is an excellent resource for a brief but very broad overview on the management of hypertension. Much of the information in this talk is actually found in these guidelines. Also want to show you what’s called the JNC 7 Reference Card. So the JNC 7 website contains the latest publication, otherwise known as the Seventh Report or the JNC 7. It’s available for download and also available as this pocket card that you can print and fold up and keep in your pocket for quick reference. And much of this talk actually comes directly from these guidelines. So it’s a very valuable resource. And I’ve included the hyperlink. So the definition of essential hypertension. Normal blood pressure is less than 120 over 80 millimeters of mercury. We define prehypertension as a systolic blood pressure between 120 and 139 over a diastolic of 80 to 89 millimeters of mercury. This is an important definition since patients with prehypertension have increased risk for cardiovascular disease. Hypertension is defined as a systolic blood pressure greater than 140 or a diastolic greater than 90 millimeters of mercury. And then we also break it down into two stages. Stage 1, it’s a range of 140 over 90 to 159 over 99 millimeters mercury. And then stage-2 hypertension is when the systolic blood pressure is greater than 160 or the diastolic is greater than 100 millimeters mercury. Next, it’s important that you accurately diagnose hypertension. This is extremely important. You want to get the diagnosis correct. And context matters, actually. You want to make sure that your patient is not acutely ill or in severe pain, that you’re present in a quiet room, patient is restful and not agitated. Diagnosis is not made with a single measurement. We actually recommend an average of two or more readings more than a minute apart on two or more visits. We do have other modalities available other than just measuring the clinic blood pressure. For instance, we can give a patient a blood pressure cuff and have them measure it themselves and keep a record. Or we can have a cuff automatically capture a measurement throughout the day and then electronically transmit that data to the provider. This is called ambulatory blood pressure monitoring. And we actually have data that suggest that ambulatory blood pressure monitoring is more sensitive and specific compared to clinic measurements alone in making the diagnosis of hypertension. Also, it’s kind of neat that ambulatory blood pressure monitoring can identify white coat hypertension, which is when blood pressure is elevated in clinic but normal at home. And also, what’s called masked hypertension, which is when blood pressure is elevated at home but normal in clinic. So the patient may ask you, why do we get essential hypertension? And the easiest response is you could say it’s poorly understood. And it’s likely a mixture of environmental and genetic factors. The vast majority of patients with hypertension have essential hypertension, which basically means there’s no underlying secondary cause to explain the hypertension. When we say there’s a mixture of environmental factors, we’re really referring to sedentary lifestyle, obesity, metabolic syndrome, high salt intake combined with what’s likely a genetic predisposition for the disease. We do, however, understand the final common mechanisms of the disease and that, generally, patients with hypertension have increased activation of the sympathetic nervous system, renal retention of sodium and water, and then activation of the renin-angiotensin-aldosterone system. Thus, it makes sense that the agents we use to lower blood pressure act on receptors and proteins involved in these pathways, such as beta-blockers and alpha-2 receptor agonists that affect the sympathetic nervous system, diuretics that help excrete sodium in water, and then ACE inhibitors, angiotensin receptor blockers, aldosterone antagonists, and even direct inhibitors of renin that act on the renin-angiotensin-aldosterone pathway. So now we’ll focus on the approach to a new diagnosis. When you have a new patient who you’ve diagnosed with hypertension, you need to think about two things. One, signs of end-organ damage, and then also a cardiovascular risk assessment. It’s important to figure out what is damaged already and what is at risk for further damage. When assessing for end-organ damage, you could look for signs for heart failure on physical exam, or an EKG could demonstrate left ventricular hypertrophy. Physical exam could unmask findings that suggest prior stroke. And a retinal examination can show signs such as arteriolar narrowing, arteriovenous nicking. Since cardiovascular disease is the thing we’re trying to prevent by controlling blood pressure, you should also assess cardiovascular risk factors such as obesity, age, family history of cardiovascular disease, dyslipidemia, physical inactivity, and tobacco abuse. In addition, take a family history to screen for familial disorders, and assess for any lifestyle factors or secondary causes that could explain the hypertension. For instance, alcohol abuse is an under-appreciated cause of hypertension. And patients who abuse drugs, especially stimulants, can have uncontrolled hypertension. Obstructive sleep apnea is now a common secondary cause of hypertension that can be effectively treated with CPAP if identified early. To screen for other secondary causes of hypertension, such as underlying renal disease or endocrinologic disease, all patients with hypertension deserve at least a urinalysis, complete blood count, serum chemistries, EKG, and lipid panel. The JNC 7 remarks that a urinary protein/creatinine ratio is optional. But you would want to obtain this in a diabetic patient or someone who is hypertensive with peripheral edema to check for glomerular disease as an underlying cause. So why treat? We do have great data that shows that the relationship between blood pressure and the risk of cardiovascular disease is continuous, consistent, and independent of any other risk factors for cardiovascular disease. Lowering the blood pressure has a proven reduction in incidence of heart attack, heart failure, stroke, and the progression of chronic kidney disease. What are the treatment targets? So it is important to know where you want to be and how to educate your patients about what are normal blood pressure goals. Basically, we want the blood pressure less than 140 over 90 millimeters of mercury in all patients. And we actually aim for less than 130 over 80 millimeters of mercury in diabetics, where we actually have data that show that the lower target blood pressure actually had lower rates of cardiovascular disease and death in this high-morbid group. Also, a blood pressure of less than 130 over 80 millimeters of mercury in patients with chronic kidney disease is recommended since achieving this goal has actually been proven to slow the progression of their chronic kidney disease in this population. So here is the approach to treatment of essential hypertension in the outpatient setting. This is an algorithm that was recommended by the JNC 7. For the hypertensive patient, you initially want to try and modify the modifiable first. And that usually involves screening for lifestyle factors that could be contributing. Your intervention here could include any or all the following– dietary salt restriction, weight loss, which is proven to lower blood pressure. There’s also the DASH diet, which is a diet rich in fruits, vegetables, low-fat dairy. Also, increased exercise and ensuring limited alcohol intake, which is 0 to 1 drinks per day for women and 0 to 2 drinks a day for men. When that fails, then we do move on to drug therapy. And here we determine the stage of hypertension to give us a sense of how many medications we should start upfront. For stage 1 hypertension, we usually start with monotherapy, typically with a thiazide diuretic or an ACE inhibitor or calcium channel blocker, and less commonly, a beta-blocker. For stage 2 hypertension, the patient is likely going to require two agents to meet goal. So we typically start two drugs upfront. One thing to emphasize is that the thiazide diuretic is still considered the first-line agent of choice to be used alone or in combination with other agents. This recommendation over other agents comes because there is a long history with thiazide diuretics demonstrating reduced cardiovascular outcomes. And now the drug is quite inexpensive. It has a relatively low side effect profile. And we believe that it actually enhances the efficacy of other antihypertensive agents. Another extremely important piece of the treatment approach is that you should adjust your treatment based on the patient’s comorbidities. Certain antihypertensive medications have specific outcome data that support their use with other comorbidities, such as diabetes, for instance. This can help you when you’re choosing your therapy for a given patient and will help personalize the care of the patient. For instance, in diabetes, ACE inhibitor and ARB therapy are strongly recommended, especially if there’s proteinuria present, given that there’s benefit in slowing the progression of diabetic nephropathy. Also, patients with chronic kidney disease benefit from ACE inhibitor/ARB therapy in slowing the progression of renal failure. In the heart failure patient, there’s data that support the use of carvedilol or metoprolol succinate in the setting of reduced systolic function. Also, ACE inhibitor/ARB therapy is also recommended, as well as aldosterone antagonists, for class-3 heart failure. For the patient with known coronary artery disease or post-myocardial infarction, they should be on a beta-blocker, ACE inhibitor, or ARB. And you can even use an aldosterone antagonist in the post-MI patient. In addition, thiazide diuretics and ACE inhibitors have proven reduction in stroke prevention. So when you’re doing your initial assessment, evaluate which comorbid conditions are present. And you can tailor your antihypertensive therapy based on these other comorbid illnesses. In summary, hypertension management requires, number one, the accurate diagnosis and a thorough assessment. It also requires that lifestyle modification is paramount. But most patients will require a drug therapy. Also, treatment should be guided by the patient’s comorbid conditions. If there are none, then actually, initial therapy should include a thiazide diuretic. Here are some of the references that I used for my talk. And I’d like to acknowledge the Duke Internal Medicine Residency program and also Duke-NUS.