Congestive Heart Failure PDF

Congestive Heart failure Introduction • CHF is a clinical condition in which the heart is unable to pump enough blood to meet the needs of tissue metabolism • Heart failure can involve the left, right or both sides of the heart Types of heart failure Left-sided heart failure • Fluid may back up...

Congestive Heart failure Introduction • CHF is a clinical condition in which the heart is unable to pump enough blood to meet the needs of tissue metabolism • Heart failure can involve the left, right or both sides of the heart Types of heart failure Left-sided heart failure • Fluid may back up in the lungs, causing shortness of breath. Right-sided heart failure • Fluid may back up into the abdomen, legs and feet, causing swelling. Systolic heart failure • The left ventricle can't contract vigorously, indicating a pumping problem. Diastolic heart failure (also called heart failure with normal ejection fraction) • The left ventricle can't relax or fill fully, indicating a filling problem. Causes of HF • Common causes are volume or pressure overload caused by congenital or acquired heart diseases • In infancy, congenital heart diseases are the most common causes of HF • Tachyarrhythmias and heart block can cause CHF at any age Causes of HF Congenital HD • Volume overload lesions such as VSD, PDA are the most common causes of CHF in the first 6 months of life • Typically, large L-R shunt lesions do not cause CHF before 6-8 weeks of age Causes of CHF Acquired Heart disease • Viral myocarditis • Acute rheumatic carditis • Rheumatic valvular heart disease Causes of HF • Idiopathic dilated cardiomyopathy • Doxorubicin cardiomyopathy • Cardiomyopathies associated with muscular dystrophies Causes of CHF (miscellaneous) Metabolic abnormalities • Severe hypoxia • Acidosis • Hypoglycemia • Hypocalcemia (newborns) Causes of HF • Hyperthyroidism • SVT • Complete heart block • Severe anaemia • Bronchopulmonary dysplasia Classification and staging of HF The New York Heart Association (NYHA) classification system: • Class I: No limitation of physical activity • Class II: Slight limitation of physical activity • Class III: Marked limitation of physical activity • Class IV: Symptoms occur even at rest; discomfort with any physical activity Staging of HF The American College of Cardiology/American Heart Association (ACC/AHA) staging system: • Stage A: High risk of heart failure but no structural heart disease or symptoms of heart failure • Stage B: Structural heart disease but no symptoms of heart failure • Stage C: Structural heart disease and symptoms of heart failure • Stage D: Refractory heart failure requiring specialized interventions Clinical Manifestations of HF In Infants: • Poor feeding of recent onset • Tachypnoea • Poor weight gain • Cold sweat on the forehead Clinical Manifestations In older children: • Shortness of breath • Easy fatiguability • Puffy eyelids • Swollen feet Clinical Manifestations Physical findings may be divided into groups based on pathophysiologic mechanisms • a. Compensatory responses to impaired cardiac function • b. Signs of pulmonary venous congestion • c. signs of systemic venous congestion Compensatory responses: • Tachycardia, gallop rhythm, weak and thready pulse and cardiomegaly • Signs of increased sympathetic discharge *growth failure, sweating, cold wet skin CM • Signs of pulmonary venous congestion • Tachypnoea • Dyspnoea on exertion (poor feeding in small infants) • Orthopnoea (in older children) • Wheezing and lung crackles CM Signs of systemic venous congestion • Hepatomegaly • Puffy eyelids • Distended neck veins and ankle oedema (in the older child CM • On CXR, cardiomegaly is almost always present • ECG: not helpful in determining presence of HF (but can help determine the cause) • ECHO confirm chamber enlargement, impaired LV function • Other investigations depending on suspected cause Chest radiograph of CHF Investigation of CHF • Complete blood count (CBC) • Urinalysis • Electrolyte levels • Renal and liver function studies • Fasting blood glucose levels • Lipid profile Investigation • Thyroid stimulating hormone (TSH) levels • B-type natriuretic peptide levels • 2-dimensional (2-D) echocardiography • Exercise testing • Pulse oximetry or arterial blood gas Management Treatment consists of: • Elimination of underlying causes or correction of precipitating or contributing causes • General supportive measures • Control of heart failure – inotropes, diuretics, afterload reducing agents Management Treatment of underlying causes or contributing factors • Surgery when feasible (valvular disease) • Antihypertensive treatment for HBP • Antiarrhythmic agents; pacemaker • Treatment of hyperthyroidism • Antipyretics for fever( if present) • Antibiotics for infection • Packed cell transfusion for anaemia General Measures • Increasing caloric density of feeds • Small frequent feeds are better tolerated • Intermittent or continuous NGT, if oral feeds are not tolerated • Salt restriction • Bed rest Drug Therapy Diuretics- controls pulmonary and systemic venous congestion • Thiazides • Rapid acting diuretics • Aldosterone antagonists Drug Therapy Rapidly-acting Inotropic agents • Catecholamines • Amrinone • Digitalis Digitalis • Increases the contractile state of the myocardium • Total Digitalizing Dose (TDD) is given to build a sufficient body store • TDD range from 20 micrograms/kg to 40-50 micrograms/kg Digitalis How to digitalize • First calculate the TDD (20-50 microgram/kg) • One half of the TDD is given, then ¼ of the TDD, then the last ¼ of the TDD at 6-8 hourly intervals • Maintenance dose is given 12 hours after the final (T)DD • The loading doses may be skipped in an infant with mild HF Digitalis • A baseline ECG and electrolytes are recommended tests • Digitalis effect: Slowing of the HR, diminished amplitude of the T wave, shortening of the QTc • Digitalis toxicity: profound sinus bradycardia, supreventricular arrhythmias, ventricular arrhythmias Afterload-reducing agents • Augment the stroke volume • Most improvement is had when used in combination with inotropes and diuretics • May be used in infants with large shunts as well as those with cardiomyopathies, severe MR or AR Vasodilators Arteriolar vasodilators • Hydralazine Venodilators • Nitroglycerin Mixed Vasodilators • Captopril • Enalapril • Nitroprusside Other Drugs used in CHF • Beta-adrenergic blockers May be beneficial in chronic CHF • Carnitine In dilated cardiomyopathy Surgical Management • Non improvement with medical therapy within a few weeks to months is an indication • Surgery may be palliative or corrective • Cardiac transplantation is an option in prrogressively deteriorating cardiomyopathy