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拡張障害（不全） について勉強しました。

拡張障害（不全）　その１（１/３）　定義と病態　

まとめ
■Diastolic heart failure occurs when signs and symptoms of heart failure are present but left ventricular systolic function is preserved (i.e., ejection fraction greater than 45 percent).

■The incidence of diastolic heart failure increases with age; therefore, 50 percent of older patients with heart failure may have isolated diastolic dysfunction.

■With early diagnosis and proper management the prognosis of diastolic dysfunction is more favorable than that of systolic dysfunction.

■Distinguishing diastolic from systolic heart failure is essential because the optimal therapy for one may aggravate the other.

■Although diastolic heart failure is clinically and radiographically indistinguishable from systolic heart failure, normal ejection fraction and abnormal diastolic function in the presence of symptoms and signs of heart failure confirm diastolic heart failure.

■The pharmacologic therapies of choice for diastolic heart failure are angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, diuretics, and beta blockers. (Am Fam Physician 2006;73:841-6.

緒言
■Three million Americans have congestive heart failure (CHF), and 500,000 new cases are diagnosed each year.

■The condition is the most common discharge diagnosis for patients older than 65 years　and is the most expensive disease for Medicare.

■Systolic and diastolic dysfunction can cause CHF.

■All patients with systolic dysfunction have concomitant diastolic dysfunction; therefore, a patient cannot have pure systolic heart failure.

■In contrast, certain cardiovascular diseases such as hypertension may lead to diastolic dysfunction without concomitant systolic dysfunction.

■Although diastolic heart failure accounts for approximately 40 to 60 percent of patients with CHF, these patients have a better prognosis than those with systolic heart failure.6

KEY RECOMMENDATIONS FOR PRACTICE
Clinical recommendations
□Systolic and diastolic hypertension should be controlled in accordance with published guidelines.
□Ventricular rate should be controlled in patients with atrial fibrillation.
□Diuretics should be used to control pulmonary congestion and peripheral edema.
□Coronary revascularization should be used in patients with coronary artery disease in whom symptomatic or demonstrable myocardial ischemia is judged to have an adverse effect on diastolic function.
□Sinus rhythm should be restored in patients with atrial fibrillation.
□Beta-adrenergic blocking agents, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or calcium antagonists should be used in patients with controlled hypertension to minimize symptoms of heart failure.
□Digitalis should be used to minimize symptoms of heart failure.
 

定義と診断基準
■Diastolic heart failure is defined as a condition caused by increased resistance to the filling of one or both ventricles; this leads to symptoms of congestion from the inappropriate upward shift of the diastolic pressure-volume relation.7

■Although this definition describes the principal pathophysiologic mechanism of diastolic heart failure, it is not clinically applicable.

■A more practical definition for use in clinical practice is: a condition that includes classic CHF findings and abnormal diastolic and normal systolic function at rest.

Diagnostic Criteria for Diastolic Heart Failure
Definitive diastolic heart failure
□Definitive evidence of congestive heart failure
and
□Objective evidence of normal left ventricular systolic function in proximity of event
and
□Objective evidence of left ventricular diastolic dysfunction

Probable diastolic heart failure
□Definitive evidence of congestive heart failure（Same as definitive）
and
□Objective evidence of normal left ventricular systolic function in proximity of event（Same as definitive）
and
□No conclusive information on left ventricular diastolic function

Possible diastolic heart failure
□Definitive evidence of congestive heart failure（Same as definitive）
and
□Left ventricular ejection fraction of 50 percent or more not measured within 72 hours of event
and
□No conclusive information on left ventricular diastolic function（Same as probable ）

●Patients who have definitive evidence of congestive heart failure and objective evidence of normal left ventricular systolic function in proximity of event are accepted as having probable diastolic heart failure provided that mitral valve disease, cor pulmonale, primary volume overload, and noncardiac causes are excluded.

●Clinical symptoms and signs, supporting chest radiography, typical clinical response to diuretics with or without elevated left ventricular filling pressure, or low cardiac index.

●Left ventricular ejection fraction of 50 percent or more within 72 hours of event.

●Abnormal left ventricular relaxation or filling or distensibility indices on catheterization.
 

発生頻度と疫学
■On average, 40 percent of patients with heart failure have preserved systolic function.

■The incidence of diastolic heart failure increases with age, and it is more common in older women.

■Hypertension and cardiac ischemia are the most common causes of diastolic heart failure .

＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿
Causes of Diastolic Dysfunction and Heart Failure
Common causes*
Cardiac ischemia
Hypertension
Aging
Obesity
Aortic stenosis
Uncommon causes
Myocardial disorders
Myocardial diseases
Infiltrative disease (e.g., amyloidosis, sarcoidosis, fatty infiltration)
Noninfiltrative diseases (e.g., idiopathic and hypertrophic cardiomyopathy)
Endomyocardial diseases
Hypereosinophilic syndrome
Storage diseases
Glycogen storage disease
Hemochromatosis
Pericardial disorders
Constrictive pericarditis
Effusive-constrictive pericarditis
Pericardial effusion
＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿ 

■Common precipitating factors include volume overload; tachycardia; exercise; hypertension; ischemia; systemic stressors (e.g., anemia, fever, infection, thyrotoxicosis); arrhythmia (e.g., atrial fibrillation, atrioventricular nodal block); increased salt intake; and use of nonsteroidal anti-inflammatory drugs.

病態生理
■Diastole is the process by which the heart returns to its relaxed state.

■During this period, the cardiac muscle is perfused.

■Conventionally, diastole can be divided into four phases: isovolumetric relaxation, caused by closure of the aortic valve to the mitral valve opening; early rapid ventricular filling located after the mitral valve opening; diastasis, a period of low flow during mid-diastole; and late rapid filling during atrial contraction.

■Broadly defined, isolated diastolic dysfunction is the impairment of isovolumetric ventricular relaxation and decreased compliance of the left ventricle.

■With diastolic dysfunction, the heart is able to meet the body's metabolic needs, whether at rest or during exercise, but at a higher filling pressure.

■Transmission of higher end-diastolic pressure to the pulmonary circulation may cause pulmonary congestion, which leads to dyspnea and subsequent right-sided heart failure.

■With mild dysfunction, late filling increases until the ventricular end-diastolic volume returns to normal. In severe cases, the ventricle becomes so stiff that the atrial muscle fails and end-diastolic volume cannot be normalized with elevated filling pressure.

■This process reduces stroke volume and cardiac output, causing effort intolerance.

Figure 1. Algorithm for pathophysiology of diastolic heart failure. Abnormal relaxation and increased stiffness are associated with diastolic filling abnormalities and normal exercise tolerance in the early phase of diastolic dysfunction. When the disease progresses, pulmonary pressures increase abnormally during exercise, producing reduced exercise tolerance. When filling pressures increase further, left atrial pressure and size increase and exercise tolerance falls as clinical signs of congestive heart failure appear.

Adapted with permission from Mandinov L, Eberli FR, Seiler C, Hess OM. Diastolic heart failure. Cardiovasc Res 2000;45:822.

＜引用サイト＞
Diagnosis and Management of Diastolic Dysfunction and Heart Failure
http://images.google.co.jp/imgres?imgurl=http://www.aafp.org/afp//AFPprinter/20060301/841_f1.gif&imgrefurl=http://www.aafp.org/afp//AFPprinter/20060301/841.html&usg=__ciV9HcoKi-Pr-lndQ7UqG65QJ9E=&h=478&w=550&sz=22&hl=ja&start=15&um=1&tbnid=PqFdCrcS-YIsOM:&tbnh=116&tbnw=133&prev=/images%3Fq%3Ddiastolic%2Bdysfunction%26ndsp%3D20%26hl%3Dja%26lr%3D%26sa%3DN%26um%3D1

＜関連サイト＞
2009 Focused Update Incorporated Into the ACC/AHA 2005 Guidelines for the Diagnosis and Management of Heart Failure in Adults
http://content.onlinejacc.org/cgi/content/full/53/15/e1
http://circ.ahajournals.org/cgi/content/full/119/14/e391