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Hypertensive Heart Disease
Causes
High blood pressure increases the pressure in blood vessels. As the heart pumps against this pressure, it must work harder. Over time, this causes the heart muscle to thicken and the left ventricle to become enlarged. The amount of blood pumped by the heart each minute (cardiac output) goes down. Without treatment, symptoms of congestive heart failure may develop.
High blood pressure is the most common risk factor for heart disease and stroke. It can cause ischemic heart disease from the increased supply of oxygen needed by the thicker heart muscle.
High blood pressure also contributes to thickening of the blood vessel walls. This may worsen atherosclerosis (increased cholesterol deposits in the blood vessels). This also increases the risk of heart attacks and stroke.
Hypertensive heart disease is the leading cause of illness and death from high blood pressure.
The heart complications that develop determine the symptoms, diagnosis, treatment, and outlook of hypertensive heart disease.
Possible Complications
* Angina
* Arrhythmias
* Heart attack
* Heart failure
* Stroke
* Sudden death
Prevention
Have your blood pressure checked at regular intervals (as recommended by your health care provider) to monitor the condition. Frequent blood pressure measurements taken at home are often recommended for people with difficult-to-control high blood pressure.
Treat your high blood pressure. Do not stop or change treatment, except on the advice of your health care provider.
Carefully control diabetes, hyperlipidemia, and other conditions that increase the risk of heart disease.
In addition to medications, recommended lifestyle changes include:
* Diet changes:
o Avoid trans fats and saturated fats
o Increase fruits, vegetables, and low-fat dairy products
o Reduce salt intake (may be beneficial)
o Eat whole grains, poultry, and fish
* Exercise regularly
* Reduce excessive alcohol consumption
* Stop smoking -- cigarettes are a major cause of hypertension-related heart disease
* Lose weight if you are overweight or obese
By Kamran Riaz, MD, Clinical Assistant Professor, Department of Internal Medicine, Section of Cardiology, Wright State University School of Medicine
Background
Uncontrolled and prolonged elevation of blood pressure (BP) can lead to a variety of changes in the myocardial structure, coronary vasculature, and conduction system of the heart. These changes can lead to the development of left ventricular hypertrophy (LVH), coronary artery disease, various conduction system diseases, and systolic and diastolic dysfunction of the myocardium, which manifest clinically as angina or myocardial infarction, cardiac arrhythmias (especially atrial fibrillation), and congestive heart failure (CHF). Thus, hypertensive heart disease is a term applied generally to heart diseases, such as LVH, coronary artery disease, cardiac arrhythmias, and CHF, caused by direct or indirect effects of elevated BP. Although these diseases generally develop in response to chronically elevated BP, marked and acute elevation of BP can also lead to accentuation of an underlying predisposition to any of the symptoms traditionally associated with chronic hypertension.
Pathophysiology
The pathophysiology of hypertensive heart disease is a complex interplay of various hemodynamic, structural, neuroendocrine, cellular, and molecular factors. On one hand, these factors play integral roles in the development of hypertension and its complications; on the other hand, elevated BP itself can modulate these factors. Elevated BP leads to adverse changes in cardiac structure and function in 2 ways: directly by increased afterload and indirectly by associated neurohormonal and vascular changes. Elevated 24-hour ambulatory BP and nocturnal BP have been demonstrated to be more closely related to various cardiac pathologies, especially in African Americans. The pathophysiologies of the various cardiac effects of hypertension differ and are described in this section.
Left ventricular hypertrophy
Of patients with hypertension, 15-20% develop LVH. The risk of LVH is increased 2-fold by associated obesity. The prevalence of LVH based on ECG findings, which are not a sensitive marker at the time of diagnosis of hypertension, is variable. Studies have shown a direct relationship between the level and duration of elevated BP and LVH.
LVH, defined as an increase in the mass of the left ventricle (LV), is caused by the response of myocytes to various stimuli accompanying elevated BP. Myocyte hypertrophy can occur as a compensatory response to increased afterload. Mechanical and neurohormonal stimuli accompanying hypertension can lead to activation of myocardial cell growth, gene expression (Some of the genes are given expression primarily in fetal cardiomyocytes.), and, thus, LVH. In addition, activation of the renin-angiotensin system, through the action of angiotensin II on angiotensin I receptors, leads to growth of interstitium and cell matrix components. Thus, the development of LVH is characterized by myocyte hypertrophy and by an imbalance between the myocytes and the interstitium of the myocardial skeletal structure.
Various patterns of LVH have been described, including concentric remodeling, concentric LVH, and eccentric LVH. Concentric LVH is an increase in LV thickness and LV mass with increased LV diastolic pressure and volume, commonly observed in persons with hypertension. Compare this with eccentric LVH, in which LV thickness is increased not uniformly but at certain sites, such as the septum. Concentric LVH is a marker of poor prognosis in the presence of hypertension. While the development of LVH initially plays a protective role in response to increased wall stress to maintain adequate cardiac output, later it leads to the development of diastolic and, ultimately, systolic myocardial dysfunction.
Left atrial abnormalities
Frequently underappreciated, structural and functional changes of the left atrium (LA) are very common in patients with hypertension. The increased afterload imposed on the LA by the elevated LV end-diastolic pressure secondary to increased BP leads to impairment of the LA and LA appendage function plus increased LA size and thickness. Increased LA size accompanying hypertension in the absence of valvular heart disease or systolic dysfunction usually implies chronicity of hypertension and may correlate with the severity of LV diastolic dysfunction. In addition to these structural changes, these patients are predisposed to atrial fibrillation. Atrial fibrillation, with loss of atrial contribution in the presence of diastolic dysfunction, may precipitate overt heart failure.
Valvular disease
Although valvular disease does not cause hypertensive heart disease, chronic and severe hypertension can cause aortic root dilatation, leading to significant aortic insufficiency. Some degree of hemodynamically insignificant aortic insufficiency is often found in patients with uncontrolled hypertension. An acute rise in BP may accentuate the degree of aortic insufficiency, with return to baseline when BP is better controlled. In addition to causing aortic regurgitation, hypertension is also thought to accelerate the process of aortic sclerosis and cause mitral regurgitation.
Heart failure
Heart failure is a common complication of chronically elevated BP. Hypertension as a cause of CHF is frequently underrecognized, partly because at the time heart failure develops, the dysfunctioning LV is unable to generate the high BP, thus obscuring the etiology of the heart failure. The prevalence of asymptomatic diastolic dysfunction in patients with hypertension and without LVH may be as high as 33%. Chronically elevated afterload and resulting LVH can adversely affect both the active early relaxation phase and late compliance phase of ventricular diastole.
Diastolic dysfunction is common in persons with hypertension. It is usually, but not invariably, accompanied by LVH. In addition to elevated afterload, other factors that may contribute to the development of diastolic dysfunction include coexistent coronary artery disease, aging, systolic dysfunction, and structural abnormalities such as fibrosis and LVH. Asymptomatic systolic dysfunction usually follows. Later in the course of disease, the LVH fails to compensate by increasing cardiac output in the face of elevated BP and the left ventricular cavity begins to dilate to maintain cardiac output. As the disease enters the end stage, LV systolic function decreases further. This leads to further increases in activation of the neurohormonal and renin-angiotensin systems, leading to increases in salt and water retention and increased peripheral vasoconstriction, eventually overwhelming the already compromised LV and progressing to the stage of symptomatic systolic dysfunction.
Apoptosis, or programmed cell death, stimulated by myocyte hypertrophy and the imbalance between its stimulants and inhibitors, is considered to play an important part in the transition from compensated to decompensated stage. The patient may become symptomatic during the asymptomatic stages of the LV systolic or diastolic dysfunction, owing to changes in afterload conditions or to the presence of other insults to the myocardium (eg, ischemia, infarction). A sudden increase in BP can lead to acute pulmonary edema without necessarily changing the LV ejection fraction. Generally, development of asymptomatic or symptomatic LV dilatation or dysfunction heralds rapid deterioration in clinical status and markedly increased risk of death. In addition to LV dysfunction, right ventricular thickening and diastolic dysfunction also develop as results of septal thickening and LV dysfunction.
Myocardial ischemia
Patients with angina have a high prevalence of hypertension. Hypertension is an established risk factor for the development of coronary artery disease, almost doubling the risk. The development of ischemia in patients with hypertension is multifactorial.
Importantly, in patients with hypertension, angina can occur in the absence of epicardial coronary artery disease. The reason is 2-fold. Increased afterload secondary to hypertension leads to an increase in left ventricular wall tension and transmural pressure, compromising coronary blood flow during diastole. In addition, the microvasculature, beyond the epicardial coronary arteries, has been shown to be dysfunctional in patients with hypertension and it may be unable to compensate for increased metabolic and oxygen demand.
The development and progression of arteriosclerosis, the hallmark of coronary artery disease, is exacerbated in arteries subjected to chronically elevated BP. Shear stress associated with hypertension and the resulting endothelial dysfunction causes impairment in the synthesis and release of the potent vasodilator nitric oxide. A decreased nitric oxide level promotes the development and acceleration of arteriosclerosis and plaque formation. Morphologic features of the plaque are identical to those observed in patients without hypertension.
Cardiac arrhythmias
Cardiac arrhythmias commonly observed in patients with hypertension include atrial fibrillation, premature ventricular contractions, and ventricular tachycardia.
The risk of sudden cardiac death is increased. Various mechanisms thought to play a part in the pathogenesis of arrhythmias include altered cellular structure and metabolism, inhomogeneity of the myocardium, poor perfusion, myocardial fibrosis, and fluctuation in afterload. All of these may lead to an increased risk of ventricular tachyarrhythmias.
Atrial fibrillation (paroxysmal, chronic recurrent, or chronic persistent) is observed frequently in patients with hypertension. In fact, elevated BP is the most common cause of atrial fibrillation in the Western hemisphere. In one study, nearly 50% of patients with atrial fibrillation had hypertension. Although the exact etiology is not known, left atrial structural abnormalities, associated coronary artery disease, and LVH have been suggested as possible contributing factors. The development of atrial fibrillation can cause decompensation of systolic and, more importantly, diastolic dysfunction, owing to loss of atrial kick, and it also increases the risk of thromboembolic complications, most notably stroke.
Premature ventricular contractions, ventricular arrhythmias, and sudden cardiac death are observed more often in patients with LVH than in those without LVH. The etiology of these arrhythmias is thought to be concomitant coronary artery disease and myocardial fibrosis.
Frequency
United States
The exact frequency is unknown. The rate of LVH based on ECG findings is 2.9% for men and 1.5% for women. The rate of LVH based on echocardiography findings is 15-20%. Of patients without LVH, 33% have evidence of asymptomatic LV diastolic dysfunction. Hypertension accounts for 10% of cases of CHF and, in the elderly population, as many as 68%. Some community-based studies have demonstrated that hypertension may contribute to the development of heart failure in as many as 50-60% of patients. In patients with hypertension, the risk of heart failure is increased by 2-fold in men and by 3-fold in women.
Mortality/Morbidity
Mortality and morbidity rates from hypertensive heart disease are higher than those of the general population and depend on the specific cardiac pathology. Data suggest that increases in mortality and morbidity rates are related more to the pulse pressure than the absolute systolic or diastolic BP levels, but all are important.
* Left ventricular hypertrophy: The development of LVH is clearly related to an increase in the cardiovascular mortality rate. The increased risk of cardiovascular events with LVH depends on the type of LVH. Concentric LVH increases the risk of cardiovascular events the most, as much as 30% over a 10-year period in one study, compared with 15% with concentric remodeling and 9% without any LVH. The degree of LVH, as assessed by LV mass index (LVMI), is also related to the cardiovascular mortality rate, with a relative risk of 1.73 for men and 2.12 for women for each 50-g/m2 increase in the LVMI over a 4-year period. With LVH, the relative risk of mortality is increased 2-fold in patients with coronary artery disease and 4-fold in patients without coronary artery disease.
Studies have also shown an increase in the risk of sudden cardiac death in patients with LVH. Regression of the LVMI has been demonstrated with several different antihypertensive medications. Although not proven, limited data suggest a reduction in LVH results in a reduction in cardiovascular events.
* LV diastolic dysfunction: The prognosis of patients with diastolic dysfunction is poor and is affected by the presence of underlying coronary artery disease. In one study, survival rates at 3 months, 1 year, and 5 years in patients with heart failure due to diastolic dysfunction were 86%, 76%, and 46%, respectively. In another study, the 7-year cardiovascular mortality rate approached 50% in patients with heart failure due to diastolic dysfunction and concomitant coronary artery disease; some also had hypertension. Even in patients with asymptomatic diastolic dysfunction due to hypertension, risk of all cause mortality and cardiovascular events is significantly increased. This risk increases with an increase in the pulmonary artery wedge pressure. LV diastolic dysfunction, and the heart failure symptoms associated with it, have been shown to improve with treatment aimed at lowering BP and reducing LVH. Whether such treatment has any effect on the mortality rate is not clear.
* LV systolic dysfunction: The mortality rate from heart failure due to systolic LV dysfunction is high and depends on the symptoms and New York Heart Association (NYHA) classification. The 5-year mortality rate for patients with heart failure due to systolic dysfunction approaches 20%, while the 2-year mortality rate in patients with NYHA class IV classification is as high as 50%. Mortality rates have decreased with use of ACE inhibitors and beta-blockers, which improve LV function.
Race
In the United States, hypertension is more prevalent in African Americans than in whites, as is death from hypertensive heart disease. This difference is attributed to factors other than race because the prevalence of hypertension among African Americans and whites is the same in the United Kingdom and because hypertension is not very common on the African continent. In addition, hypertension is the most common etiology of heart failure in African Americans in the United States.
Sex
Systolic BP increases with age. This increase is more marked in men until women reach menopause, when BP rises more sharply in women and reaches levels higher than in men. The prevalence of hypertension is higher in men younger than 55 years but is higher in women older than 55 years. The prevalence of hypertensive heart disease probably follows the same pattern.
Age
BP increases with age, as does the prevalence of hypertensive heart disease, which is affected by the severity of BP increase.
Clinical
History
Symptoms of hypertensive heart disease depend on the duration, severity, and type of disease. In addition, the patient may or may not be aware of the diagnosis of hypertension.
* Left ventricular hypertrophy: Patients with LVH alone are totally asymptomatic unless the LVH leads to the development of diastolic dysfunction and heart failure.
* Heart failure
o Although symptomatic diastolic heart failure and systolic heart failure are indistinguishable, the clinical history may be quite revealing. In particular, individuals who abruptly develop severe symptoms of CHF and rapidly return to baseline with medical therapy are more likely to have isolated diastolic dysfunction.
o Heart failure symptoms include the following:
+ Exertional and nonexertional dyspnea (NYHA classes I-IV)
+ Orthopnea
+ Paroxysmal nocturnal dyspnea
+ Fatigue (more common in systolic dysfunction)
+ Ankle edema and weight gain
+ Abdominal pain secondary to congested, distended liver
+ Altered mentation in severe cases
o Patients can present with acute pulmonary edema due to sudden decompensation in LV systolic or diastolic dysfunction caused by precipitating factors such as acute rise in BP, dietary indiscretion, or myocardial ischemia. Patients can develop cardiac arrhythmias, especially atrial fibrillation, or they can develop symptoms of heart failure insidiously over time.
* Myocardial ischemia
o Angina, a frequent complication of hypertensive heart disease, is also indistinguishable from other causes of myocardial ischemia.
o Typical symptoms of angina include substernal chest pain lasting less than 20 minutes (versus >20 min in infarction). Pain is described in the following ways:
+ Heaviness, pressure, squeezing
+ Radiating to neck, jaw, upper back, or left arm
+ Provoked by emotional or physical exertion
+ Relieved with rest or sublingual nitroglycerin
o Patients also may present with atypical symptoms without chest pain, such as exertional dyspnea, commonly referred to as an angina equivalent.
o The patient may present with chronic stable angina or acute coronary syndrome, including myocardial infarction without ST-segment elevation and acute myocardial infarction with ST elevation. Ischemic ECG changes may be found in individuals presenting with hypertensive crisis in whom no significant coronary atherosclerosis is detectable by coronary angiography.
o Acute coronary symptoms can be precipitated by a ruptured atherosclerotic plaque or by an acute and severe rise in BP leading to a sudden increase in transmural pressure without a change in stability of the plaque.
* Cardiac arrhythmias: These can cause a variety of symptoms, including palpitations, near or total syncope, precipitation of angina, sudden cardiac death, and precipitation of heart failure, especially with atrial fibrillation in diastolic dysfunction.
Physical
Physical signs of hypertensive heart disease depend on the predominant cardiac abnormality and the duration and severity of the hypertensive heart disease. Findings from the physical examination may be entirely normal in the very early stages of the disease, or the patient may have classic signs upon examination. In addition to generalized findings attributable directly to high BP, the physical examination may reveal clues to a potential etiology of hypertension, such as truncal obesity and striae in Cushing syndrome, renal artery bruit in renal artery stenosis, and abdominal mass in polycystic kidney disease.
* Pulses: The arterial pulses are normal in the early stages of the disease.
o Rhythm
+ Regular if the patient is in sinus rhythm
+ Irregularly irregular if the patient is in atrial fibrillation
o Rate
+ Normal in patients in sinus rhythm and not in decompensated heart failure
+ Tachycardic in patients with heart failure and in patients with atrial fibrillation and a rapid ventricular response
o Volume
+ Normal
+ Decreased in patients with LV dysfunction
o Additional findings - May include radial-femoral delay if the etiology of hypertension is coarctation of the aorta
* Blood pressure: Systolic and/or diastolic BP is elevated (>140/90 mm Hg). Mean BP and pulse pressure generally are also elevated. The BP in the upper extremities may be higher than that in the lower extremities in patients with coarctation of the aorta. BP may be normal at the time of evaluation if the patient is on adequate antihypertensive medications or the patient has advanced LV dysfunction and the LV cannot generate enough stroke volume and cardiac output to produce an elevated BP.
* Veins: In patients with heart failure, jugular veins may be distended; the predominant waves depend on the severity of the heart failure and any other associated lesions.
* Heart
o Apex: The apical impulse is sustained and nondisplaced in patients without significant systolic LV dysfunction but with LVH. A presystolic S4 may be felt. Later in the course of disease, when significant systolic LV dysfunction supervenes, the apical impulse is displaced laterally, owing to LV dilatation.
o Right ventricle: A lift is present late in the course of heart failure if significant pulmonary hypertension develops.
o Heart sounds: S1 is normal in intensity and character. S2 at the right upper sternal border is loud because of an accentuated aortic component (A2); it can have a reverse or paradoxical split due either to increased afterload or to associated left bundle-branch block (LBBB). S4 frequently is palpable and audible, implying the presence of a stiffened, noncompliant ventricle due to chronic pressure overload and LVH. S3 typically is not present initially but is audible in the presence of heart failure, either systolic or diastolic.
o Murmurs: An early decrescendo diastolic murmur of aortic insufficiency may be heard along the mid-to-left parasternal area, especially in the presence of acutely elevated BP, frequently disappearing once the BP is better controlled. In addition, an early to mid systolic murmur of aortic sclerosis is commonly audible. A holosystolic murmur of mitral regurgitation may be present in patients with advanced heart failure and dilated mitral annulus.
* Lungs: Findings upon chest examination may be normal or may include signs of pulmonary congestion, such as rales, decreased breath sounds, and dullness to percussion due to pleural effusion.
* Abdomen: Abdominal examination may reveal a renal artery bruit in patients with hypertension secondary to renal artery stenosis, a pulsatile expansile mass of abdominal aortic aneurysm, and hepatomegaly and ascites due to CHF.
* Extremities: Ankle edema may be present in patients with advanced heart failure.
* CNS and retina
o CNS examination findings are usually unremarkable unless the patient has had previous cerebrovascular accidents with residual deficit.
o Examination of the fundi may reveal evidence of hypertensive retinopathy, the severity of which depends on the duration and severity of hypertension, or earlier signs of hypertension such as arteriovenous nicking.
Causes
The cause of hypertensive heart disease is chronically elevated BP. The causes of elevated BP are diverse. In adults, the following causes should be considered:
* Essential hypertension accounts for 90% of cases of hypertension in adults.
* Secondary causes of hypertension account for the remaining 10% of cases of chronically elevated BP. These include the following:
o Renal causes
+ Renal artery stenosis
+ Polycystic kidney disease
+ Chronic renal failure
+ Intrarenal Vasculitis
o Endocrine causes
+ Primary hyperaldosteronism
+ Pheochromocytoma
+ Cushing syndrome
+ Congenital adrenal hyperplasia
+ Hypothyroidism and hyperthyroidism
+ Acromegaly
+ Exogenous hormone (eg, corticosteroids, estrogens), sympathomimetics, monoamine oxidase inhibitors (MAOIs), and tyramine-containing foods
o Others
+ Coarctation of aorta
+ Raised intracranial pressure
+ Sleep apnea
+ Isolated systolic hypertension - Can be observed in elderly people, due to increased stiffness of the vasculature
+ Isolated systolic hypertension - Can be observed in thyrotoxicosis, atrioventricular (AV) fistula, aortic regurgitation, beriberi, Paget disease, and patent ductus arteriosus (ie, due to increase cardiac output secondary to a hyperdynamic circulation)
Definition
Hypertensive heart disease is a late complication of hypertension (high blood pressure) in which the heart is affected.
Causes, incidence, and risk factors
High blood pressure increases the heart's workload, and over time, this can cause the heart muscle to thicken. As the heart pumps against elevated pressure in the blood vessels, the left ventricle becomes enlarged and the amount of blood pumped by the heart each minute (cardiac output) goes down. Without treatment, symptoms of congestive heart failure may develop.
High blood pressure is the most common risk factor for heart disease and stroke. It can cause ischemic heart disease (decreased blood to the heart muscle that results in anginal chest pain and heart attacks) from the increased supply of oxygen needed by the thicker heart muscle.
High blood pressure also contributes to thickening of the blood vessel walls, which in turn may aggravate atherosclerosis (increased cholesterol deposits in the blood vessels). This also increases the risk of heart attacks and stroke.
Hypertensive heart disease is the leading cause of illness and death from hypertension. It affects approximately 7 out of 1,000 people.
Symptoms
High blood pressure is known as a silent killer, because by the time symptoms of hypertensive heart disease appear, the condition can be life-threatening. Congestive heart failure is one possible result of hypertensive heart disease. Symptoms of congestive heart failure include:
* Shortness of breath, especially with activity
* Waking at night with shortness of breath
* Need to sleep with the head elevated to avoid shortness of breath
* Rapid or irregular pulse
* Sensation of feeling the heart beating (palpitations)
* Cough, which may produce frothy or bloody mucus
* Fatigue, weakness, faintness
* Swelling of the feet and ankles
* Increased frequency of urination at night
Ischemic heart disease is another possible result of hypertensive heart disease. Symptoms include:
* Chest pain, pressure-type, particularly with exertion
* Chest pain associated with:
o Nausea
o Sweating
o Dizziness
o Shortness of breath
A third possible result is hypertrophic cardiomyopathy.
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