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Paper Topic:

CHF

Congestive Heart Failure

Outline

Definition /Epidemiology

Classifications

Etiology

Pathophysiology

Diagnosis

Therapy

CHF - Definition

Congestive Heart Failure is defined as a syndrome including symptoms of circulatory congestion and inadequate end organ perfusion due to abnormal heart function and neurohormonal abnormalities . The incidence if CHF has doubled in past 30 years due to aging population and increased survival post -MI . It is most common cause of hospitalization after the age of 65 years . About one third of the patients require further readmission within 90 days . It carries

a high 5 - year mortality rate (50 ) when untreated

Etiology

Coronary artery disease is responsible for more than two third cases of CHF in Canada . Myocardial ischemia or cardiomyopathies cause stunning or decrease in wall motion of the heart muscle directly causing congestive heart failure (systolic dysfunction . Valvular diseases including infective endocarditis (AS and MR ) also present with left ventricular failure . Cardiac tamponade , constriction pericarditis and cardiac arrythmias (tachy and bradyrrythmias ) many a times precipitate the failure . Vascular causes including hypertension cause congestive cardiac failure by causing chronic increase in afterload . Hypertension is most common cause of left heart failure and left heart failure is most common cause of right heart failure . Congenital anamolies e .g . tertalogy of fallot cause CHF in infants and children

Who gets CHF

Predisposing factors

Following set of factors predispose to the development of CHF

Advancing Age : It is the Most common reason for hosiptalization in elderly

Sex

Men at a higher risk

Woman have a better survival rate

African-American Ethnicity have a 30 higher mortality rate

Family History and Genetics

Pathophysiology of CHF

Before we describe the pathophysiology of CHF , we have to understand few terms . Wall tension of myocardium is dependent upon preload and afterload of the heart . Preload is defined in simple terms as the volume of blood filling the ventricle in diastole . Preload is further dependent upon ventricular filling pressure or left ventricular end diastolic volume (LVEDV . Afterload is defined as the forces against which the left ventricle must work to eject blood into the systemic circulation Contractility is the intrinsic property of the cardiac muscle . Frank - Starling hypothesis states that the myocardial sarcomere length is stretched by increases in preload that further increases the force of contraction . Pathophysiology of CHF is described under the following heads Initial insult , adaptive responses and the stage of decompensation

Initial insult

The initial injury to the vascular system that involves the decreased in cardiac output . It occurs due to ischemia (unstable angina , infarction (myocardial infarction ) and some valvular disease

Adaptive response

As a result of the cellular level injury caused by ischemia , infarction and valvular diseases , varoius types of mediators are released to cause the neurohormonal stimulation . The varoius neurohormonal factors are RAA , and ADH release , adrenergic stimulation , ventricular stretch and increased sarcomere number and size to reduce wall stress . RAA , and ADH cause salt and water retention causing increased preload . Atrial Natriuretic Peptide and Brain Natriuretic Peptide are also released Adrenergic stimulation and ventricular stretch causes increased contractility...

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