Congestive Heart FailureOutlinen Definition/Epidemiologyn Classificationsn Etiologyn Pathophysiologyn Diagnosisn TherapyCHF – DefinitionCongestive 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:(i) Advancing Age: It is the Most common reason for hosiptalization in elderly.(ii) Sex:a. Men at a higher riskb. Woman have a better survival rate(iii) African-American Ethnicity have a 30% higher mortality rate(iv) Family History and GeneticsPathophysiology 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 decompensationInitial 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 of the heart muscle. Increased sarcomere number and size to reduce wall stress (Law of Laplace) causes a more chronic response in the form of myocardial hypertrophy.
Decompensation:LV remodelling plays an important part in the decompensation process.cardiac output decreases due to LV remodelling and cellular exhaustion causin LV dilatation (Dilated cardiomyopathy). Volume overload from excessive salt and water retention is always seen in congestive heart failure due to increased renin, angiotesin and aldosterone activity. In cases of systolic left ventricular failure the pulmonary circulation becomes congested due to increased filling pressures causing congestive cardiac failure.
The heart in congestive cardiac failure is always more prone to arrhythmogenic factors and proarrythmic agents.Classifications:CHF has been classified over a number of years as(i) Right vs. Left(ii) Systolic vs. Diastolic(iii) Forward vs. Backward(iv) High output vs. Low output(v) Acute vs.
chronic(vi) FunctionalRight sided Heart Failure:Etiology:The most common cause of right heart failure is left heart failure. The other important cause of right heart failure is Acute inferior wall MI. Other causing the right heart overload causing RHF is pulmonary disease; COPD, Pleural effusions, fibrosis and pulmonary HTNPathophysiology:The decrease in right sided ventricular output or increase in pulmonary vascular resistance causes increased right ventricular pressures. This causesd increased vascular congestion and hence capillary leak causing dependent edema and systemic venous congestion.Signs and Symptoms:The signs and symptoms are raised JVP, hypotension, peripheral edema, ascites, hepatomegaly and poor exercise toleranceDiastolic dysfunction:Etiologies:Coronary ischemiaLeft ventricular hypertrophy secondary to HTNInfiltrative diseaseAgingConstrictive pericarditisPathophysiology:The decrease in ventricular compliance due to hypertrophy or ischemia results in increase in LVEDP to cause decreased ventricular filling and hence leading to decreased stroke volume.High Output Cardiac Failure:The high output cardiac failure is seen in cirtain physiological and diseased conditions like anemia, A-V shunt (A-V fistula, ASD,VSD), hyperthyroidism, pregnancy and beri-beri.Functional Classification of Heart FailureIt is important in prognostication and clinicallyClass Annual MortalityNYHA I – ASx with normal activity 5%NYHA II – SOB; 2 blocks or 2 flights of stairs 5-10%NYHA III – SOB < 2 blocks 10-20%NYHA IV – SOB at rest 20-50%LV Systolic Dysfunction vs.
LVEF:Normal LV function LVEF > 60%Adequate LV function LVEF 50 – 60%Mild LV Systolic Dysfunction LVEF 40 – 50%Moderate LV Systolic Dysfunction LVEF 30 – 40%Severe LV Systolic Dysfunction LVEF< 30%Diagnosis:Diagnosis of CHF is based on pateints history, physical examination, Chest X-ray and Lab reports. The signs and symptoms of CHF are dyspnea, orthopnea, paroxysmal nocturnal dyspnea (PND), cough, fatigue, anorexia, weight gain and edema (pitting). Fatigue may be one of the earliest symptoms of CHF. It often becomes important to differentiate between cardiac failure and respiratory conditions (COPD).
The latter alos presents with dyspnea, cough, fatigue. Differentiation is done by clinical examination and Chest X-Ray findings. Clinical diagnosis of CHF is based on following findings(i) History of orthopnea (breathlessness on lying in supine position)(ii) Fluid retention (pitting edema and engorged neck veins)(iii) Elevation of pressure in veins of neck (reised JVP)(iv) Irregular heart sounds and murmurs (Physical examination)(v) Swelling and tenderness in liver(vi) creptitation at the lung fields, particularly in the lower regions.
(vii) enlarged heart (evident on chest X-Ray).Diagnosis of CHF: Diagnosis of CHF is based on following findings(i) History of orthopnea (breathlessness on lying in supine position)(ii) Fluid retention (pitting edema and engorged neck veins)(iii) Elevation of pressure in veins of neck (reised JVP)(iv) Irregular heart sounds and murmurs (Physical examination)(v) Swelling and tenderness in liver(vi) creptitation at the lung fields, particularly in the lower regions.(vii) ECG: Can NOT diagnose CHF, but can indicate underlying problems like ischemia as a cause of LV dysfunction.(viii) Englarged Heart (evident on Chest X-Ray)(ix) Blood tests: Cholesterol and lipid levels, AnemiaAtrial Natriuritic Peptide (ANP) and Brain Natriuritic Peptide (BNP) are the markers of CHF and also help in the prognosis of the patients with the disease. ANP is released by atria and BNP by diseased ventricles in response to CHF(x) Exercise Stress Test; This test measures HR, BP, and O2 consumption while performing physically activity.
It is done to asses the functional capacity of the patient.Treatment:Treatment of the CHF incudes medical therapy with ACE-inhibitors / ARBs, B-Blockers (monitor the LV dysfunction), Diuretics (most important in acute cases), Vasodilators, Digoxin and Anticoagulation. Severe LV dysfunction with A – V dyssynchrony require often the permanent pacemeker implantation. Chronic CHF cases management includes lifestyle modifications in addition to the medical therapy. The recommendations are the following;(i) Monitor wt change: A sudden increase in weight may indicate fluid retention. Fluid restriction is indicated.(ii) Dietary Factors:Mediterranean Diet; Fish, olive oil, garlic, and moderate daily intake of winePotassium Rich Foods; Bananas, oranges, prunesDecrease the salt intake (especially those with high BP)(iii) Exercise: Traditionally it is not recommended for patients with severe LV dysfunction.
Patients with moderate LV dysfunction may perform the exercise in moderation with consultant physician.(iv) Warm Baths and Saunas: Traditionally not recommended. Warm water may behave like a vasodilating drug, opening muscle and improving circulation.BNP in CHF: BNP in CHF is new entity in research. Atrial Natriuritic Peptide (ANP) and Brain Natriuritic Peptide (BNP) are the markers of CHF and also help in the prognosis of the patients with the disease. ANP is released by atria and BNP by diseased ventricles in response to CHF. Both ANP and BNP and natriuritic, diuretic and vasodilators. Hence they help to alter the pathophysiology of CHF.
A new ANP analogue nesiritide is available for its use in the treatment of CHF.Nursing Care in congestive cardiac failureCongestive heart failure (CHF) is an enormous burden on society and the health care system. The role of the advanced practice nurse (APN) in CHF is a multifaceted and combines inpatient, outpatient, and community patient care skills.
Case management and quality management have been traditional focuses, with a high level of practice impact on patient care. Outcomes management in the APN role for CHF care is the future for measurable outcomes and maximum impact on organizational values. Because outcomes management is an evolving field for the APN, focus on a chronic disease such as CHF is a very valuable tool for implementation.References(i) AHA: Heart disease and stroke statisticsâ€”2004 update. Accessed June 6, 2005 . Dallas: American Heart Association; 2004(ii) Barlow JF: New rapid laboratory test for congestive heart failure B-type natriuretic peptide (BNP).
S D J Med 2002 Nov; 55(11): 467.(iii) Bax JJ, Van der Wall EE, Schalij MJ: Cardiac resynchronization therapy for heart failure. N Engl J Med 2002 Nov 28; 347(22): 1803-4; author reply 1803-4(iv) Cleland JG, Cohen-Solal A, Aguilar JC, et al: Management of heart failure in primary care (the IMPROVEMENT of Heart Failure Programme): an international survey. Lancet 2002 Nov 23; 360(9346): 1631-9.(v) Flaker GC, Singh VN: Prevention of myocardial reinfarction. Recommendations based on results of drug trials. Postgrad Med 1993 Nov 1; 94(6): 94-8, 102-4(vi) Gottlieb SS, Fisher ML: Cardiac resynchronization therapy for heart failure.
N Engl J Med 2002 Nov 28; 347(22): 1803-4; author reply 1803-4(vii) Ho KK, Pinsky JL, Kannel WB, Levy D: The epidemiology of heart failure: the Framingham Study. J Am Coll Cardiol 1993 Oct; 22(4 Suppl A): 6A-13A(viii) Advanced practice nursing for congestive heart failure Crit Care Nurs Q. 1999 Feb;21(4):1-8http://www.emedicine.com/emerg/topic108.htm