Ccf

PEDIATRICS CARDIAC FAILURE

1. CONGESTIVE CARDIAC FAILURE PEDIATRICS G.ERIC™ MD4

2. Congestive cardiac failure is the inability of the heart to maintain an output, at rest or during stress, necessary for the metabolic needs of the body (systolic failure) and inability to receive blood into the ventricular cavities at low pressure during diastole (diastolic failure).

3. An increase in left sided pressures results in dyspnea from pulmonary congestion. An increase in right sided pressures results in hepatomegaly and edema.

4. Etiopathogenesis Rheumatic fever and rheumatic heart disease is typically encountered beyond 5 yr age; its prevalence appears to be declining in selected urban populations. Heart failure from congenital heart disease typically happens within the first 1-2 yr of life. Patients with left to right shunts tend to develop CCF around six to eight weeks of life. Heart failure from congenital heart disease typically happens within the first 1-2 yr of life. Patients with left to right shunts tend to develop CCF around six to eight weeks of life.

5. Arrhythmias are an important cause of congestive cardiac failure in infancy. Three-quarters of infants with paroxysmal supraventricular tachycardia are below 4 months old. Heart rates above 180/min tend to precipitate heart failure. If the tachycardia persists for 36 hr, about 20% will develop heart failure and almost 50% will do so in 48 hr.

6. Causes of congestive cardiac failure Infants Congenital heart disease Myocarditis and primary myocardial disease Tachyarhythmias , bradyarhythmias Kawasaki disease with coronary occlusion Pulmonary hypertension (persistent pulmonary hypertension of the newborn; primary pulmonary hypertension; hypoxia, e.g. upper airway obstruction)

7. Miscellaneous causes Anemia Hypoglycemia Infections Hypocalcemia Neonatal asphyxia (myocardial dysfunction, pulmonary hypertension)

8. Children Rheumatic fever, rheumatic heart disease Congenital heart disease complicated by anemia, infection or endocarditis Systemic hypertension Myocarditis , primary myocardial disease Pulmonary hypertension (primary, secondary)

9. Clinical Features The recognition of cardiac failure in older children is based on the same features as in adults. Symptoms . Slow weight gain is related to two factors. The infant takes small feeds because of easy fatigability and there is an excessive loss of calories from increased work of breathing. Uncommonly, there may be an unusual gain in weight due to collection of water, manifesting as facial puffiness or rarely as edema on the feet.

10. Often a mother may state that the baby breathes too fast while feeding or that the baby is more comfortable and breathes better when held against the shoulder-which is the equivalent of orthopnea in older children. Not infrequently, the baby is brought with persistent hoarse crying, wheezing, excessive perspiration and less commonly, because of facial puffiness

11. Signs. Left sided failure is indicated by tachypnea and tachycardia . Persistent cough , especially on lying down, hoarse cry and wheezing are other evidences of left sided failure; basal rales in the chest are usually not audible.

12. Right-sided failure is indicated by hepatomegaly and facial puffiness. Examination of the neck veins in small babies is not helpful. Firstly, it is difficult to evaluate the short neck with baby fat and secondly, hemodynamic studies show that right atrial mean pressures stays normal in more than one-half of infants with congestive failure. Edema on the feet occurs late. Common to both left and right sided failure is the presence of cardiac enlargement, third sound gallop and poor peripheral pulses with or without cyanosis

13. Signs of congestive cardiac failure Left sided failure Tachypnea Tachycardia Cough Wheezing Rales in chest Right-sided failure Hepatomegaly Facial edema Jugular venous engorgement Pedal edema Failure of either side Cardiac enlargement Gallop rhythm (S3) Peripheral cyanosis Small volume pulse Lack of weight gain

14. Treatment Management of heart failure is a four-pronged approach for correction of inadequate cardiac output. The fourprongs are: ( i ) reducing cardiac work , (ii) augmenting myocardial contractility, (iii ) improving cardiac performance, (iv) correcting the underlying cause Identification of the cause is important since it has direct bearing on survival.

15. Reducing Cardiac Work The work of the heart is reduced by restricting patient activities, sedatives, treatment of fever, anemia, obesity, and by vasodilators. Mechanical ventilation helps when heart failure is severe by eliminating the work of breathing.

16. Neonates with heart failure are nursed in an incubator. They are handled minimally. The baby is kept propped up at an incline of about 30 ° . The pooling of edema fluid in the dependent areas reduces the collection of fluid in lungs, thus reducing the work of breathing. At a temperature of 36-37 ° C, the overall circulatory and metabolic needs are minimal, thus reducing work of heart.

17. If the infant or the child is restless or dyspneic , sedatives are used. Morphine sulfate in doses of 0.05 mg/kg SC provides effective sedation. A benzodiazepine such as midazolam is useful for sedation in selected circumstances. Sedatives reduce anxiety and lower the catecholamine secretion, thus reducing physical activity, respiratory and heart rate. Requirement of oxygen for body tissues goes down, and this reduces the cardiac workload.

18. Fever, anemia or infection also increase the work of the heart. In infants and smaller children the presence of superadded pulmonary infection is difficult to recognize. Antibiotics are therefore, sometimes administered empirically. In older children antibiotics are used, only if evidence of infection is present

19. Anemia imposes stress on the heart because of the decreased oxygen carrying capacity of blood. Anemia results in tachycardia and in a hyperkinetic circulatory state. Correction of anemia will result in decreased cardiac work. If transfusion is indicated packed red cells can be administered. Typically packed cell volumes of 10-20 ml/ kg are required to correct severe anemia; a single dose of frusemide IV is often given prior to the transfusion. Less common conditions causing stress to the heart are repeated pulmonary emboli, thyrotoxicosis and obesity.

20. Vasodilators counteract the compensatory mechanisms in heart failure and improve cardiac outputArteriolar and venous vasoconstriction is mediated through catecholamines . Arteriolar constriction maintains blood pressure by increasing the systemic vascular resistance, which increases the work of heart. Nitrates are used as preferential venodilators and hydralazine as an arteriolar dilator.

21. ACE inhibitors ( captopril , enalapril ) are effective for treating heart failure in infants and children. These agents are effective vasodilators, suppress renin-angiotensinaldosterone system, reducing vasoconstriction and salt and water retention. By suppressing catecholamines , they prevent arrhythmias and other adverse effects on the myocardium. The major side effect of ACE inhibitors is cough, which can be troublesome. Persistent cough may necessitate the use of angiotensin receptor blockers, such as losartan .

22. Initially it is necessary to monitor the renal function: urinalysis, blood levels of creatinine and electrolytes once a week for six to eight weeks. These medications may cause first-dose hypotension; the first dose should be one-quarter of the calculated dose. The patient should ideally remain recumbent for the first 6 hr to prevent an unusual fall in blood pressure.

23. Although beta-blockers might precipitate CCF, they improve symptoms and survival especially in patients with dilated cardiomyopathy , who continue to have tachycardia. Useful agents include metoprolol and carvedilol . The latter is preferred since it has properties of betablockers with peripheral vasodilation ; treatment is started at low dose and increased depending on tolerability (0.08 to 0.4 mg/kg/day, maximum 1.0 mg/kg/day). Calcium channel blockers have adverse effects in heart failure and should be avoided unless indicated for systemic hypertension.

24. In the acute care setting, sodium nitroprusside is used as a vasodilator, since it acts on the venous and arterial systems. These agents have powerful vasodilatory and inotropic effects. Specific indications for use of vasodilators include acute mitral or aortic regurgitation, ventricular dysfunction resulting from myocarditis , anomalous coronary artery from pulmonary artery and in the early post operative setting.

25. Augmenting Myocardial Contractility Augmenting myocardial contractility by inotropic agents like digitalis improves cardiac output. In infants and children, only digoxin is used. It has a rapid onset of action and is eliminated quickly. It is available for oral and parenteral administration. Oral digoxin is available as 0.25 mg tablets and as digoxin elixir (1 ml = 0.05 mg) (Table 15.6). Parenteral digoxin (0.5 mg/2 ml) is available; its dose is 70% of the oral dose. Infants tolerate digitalis well. In a hospitalized patient full digitalization should be sought to maximize benefit. Children are digitalized within a 24 hr period; 1h of the calculated digitalizing dose is given initially, followed by % in 6-8 hr and the final % after another 6-8 hr. The maintenance dose is usually one-quarter of the digitalizing dose

26. Before the third daily dose, an electrocardiogram is done to rule out digitalis toxicity. Toxicity can be controlled by omitting the next one or two doses. Digitalis is used with caution in the following situations: ( i ) premature neonates; (ii) heart failure due to myocarditis ; and (iii) very cyanotic patients. In other situations, it is better to use half the calculated digitalizing and the maintenance dose initially. Myocardial damage, gross cardiomegaly , hypoxia, acidosis, hepatic, renal and pulmonary insufficiency increase the sensitivity of the myocardium to digitalis. Digoxin is beneficial for symptom relief and is advised in patients with mild, moderately severe or severe congestive failure, with or without sinus rhythm. Digoxin can be combined with ACE inhibitors for synergistic effect. By increasing cardiac output, digoxin lowers systemic impedance indirectly, unloading the ventricles

27. Inotropic Agents These agents belong to two groups: ( i ) catecholamine inotropes , like dopamine, dobutamine and adrenaline and (ii) phosphodiesterase inhibitors like amrinone and milrinone . These agents combine inotropic effects with peripheral vasodilation . If blood pressure is low, dopamine should be used, as an intravenous infusion. At a dose of less than 5 microgram/kg per minute, dopamine causes peripheral vasodilation and increases myocardial contractility. Renal blood flow improves, resulting in natriuresis ; higher doses result in peripheral vasoconstriction. The dose of dobutamine is 2.5 to 15 microgram/ kg/ min; the dose should be increased gradually until the desired response is achieved. In patients with dilated cardiomyopathy , dobutamine is used as 24 hr infusion once or twice a week and retains its effectiveness for varying lengths of time.

28. Improving Cardiac Performance by Reducing Venous Return (Preload) Diuretics reduce the blood volume, decrease venous return and ventricular filling. This tends to reduce the heart size. The larger the heart, the more the wall tension and the poorer is its performance. With reduction in heart size and volume, the myocardial function and the cardiac output improve. Diuretics reduce the total body sodium thereby, reducing blood pressure and peripheral vascular resistance. This helps in increasing the cardiac output and reducing the work of the heart.

29. Diuretics are the first line of management in congestive failure. The action of oral frusemide starts within 20 min. Frusemide should be used in combination with a potassium sparing diuretic ( triamterene , spironolactone , amiloride ) instead of using potassium supplements. The combination prevent potassium and magnesium loss and reduces the risk of arrhythmias. Frusemide activates the renin angiotensin aldosterone axis, which is responsible for vasoconstriction and sodium and water retention. When frusemide is combined with ACE inhibitors, the combination suppresses the axis and is therefore synergistic.

30. The other method of altering the body fluid volume is by restricting the sodium intake. Sodium restriction is difficult to implement in infants and young children. Low sodium diets should be used only if the heart failure cannot be controlled with digitalis, diuretics and ACE inhibitors. However, it is prudent to advise such patients to avoid salt rich foods such as chips and pickles. Since heart failure increases calorie requirements, adequate intakes is advised.

31. Dosage of digoxin and diuretics Digitalizing dose, mg/kg Maintenance (fraction of digitalizing dose) Digoxin Premature, neonates 1 month to one year 1 to 3 yr Above 3 yr 0.04 0.08 0.06 0.04 1/4 1/3to1/4 1/3to1/4 1/3 Diuretics Frusemide Spironolactone 1-3 mg/kg per day orally or 1 mg/kg per dose IV 1 mg/kg orally every 12 hr

32. Prognosis The mortality of CCF in children is high and prognosis depends on the underlying cause.