Ghai Essential Pediatrics8th

acute regurgitant lesions like acute tricuspid, aortic or mitral regurgitation. With inadequate treatment, the course is downhill and death within 6-weeks from the onset. Metastatic lesions causing abscesses in the central nervous system, spleen, mesentery, bones and joints are common. Metastatic abscesses are rare in subacute endocarditis.

Patients with endocarditis of the right side, such as tricuspid or the pulmonary valve, throw emboli to the lungs. The embolic episodes to lungs may present as repeated episodes of pneumonitis or septic infarcts resulting in lung abscesses. It is more common in patients with indwelling central catheters, intravenous drug abuse and with VSD. Fever may occasionally present in some patients with right-sided endocarditis. Some patients remain afebrile for several days at a time and yet have large vegetations and elevated acute phase reactants.

Postoperative endocarditis. Postoperative endocarditis is classified as early (<12 months) and late. Early endo­ carditis is usually due to pyogenic organisms such as staphylococcus, pseudomonas or gram negative bacilli introduced at the time of operation. These patients have highfeverwithchills andrigors and features of septicemia. Late endocarditis is more like native valve endocarditis and the commonest organisms are S. viridans and gram negative bacilli; these patients have a subacute course. Cardiac operations are an important predisposing factor for gram negative endocarditis. Prosthetic valve endo­ carditis may also be early or late and behaves as above.

Fungalendocarditis. With extensive use of broad-spectrum antibiotics, yeast and fungal infections occur more frequently than before specially following cardiac operations and in intensive care settings. Candida is by far the commonest fungus responsible; others include

and Mucor. Fungemia is high and the organism is easily cultured from the peripheral blood. Predisposing factors for fungal endocarditis include intravenous drug abuse, indwelling catheters, intensive antibiotic therapy, prolonged steroid administration, radiation, immuno­ suppressive therapy and prosthetic valves. Incidence of embolism is higher since the fungal vegetations tend to be very large. Despite intensive therapy, mortality is high.

Laboratory Diagnosis

Blood culture is essential for diagnosis. A positive blood culture in a patient with underlying heart disease, suspected to have endocarditisis confirmatory. Three sets of cultures, each containing adequate volumes of blood, taken every half-hour are appropriate and detect 95% cases. The commonest cause for negative cultures is prior antibiotic therapy or unsatisfactory culture technique. Infectionwithunusualorganisms, anerobic organisms and fungi require special mediums and incubation for 2-3 weeksbeforedeclaringthatthe cultureisnegative. Arterial

Disorders of Cardiovascular System -

sampling does not offer any advantage over venous samples. Other investigations, which provide supportive evidence for the diagnosis, include:

i.Normocytic normochromic anemia

ii.Moderately elevated total leukocyte count

iii.Reduced platelet count

iv.Elevated sedimentation rate and C-reactive protein

v.Microscopic hematuria and albuminuria in more than 95%.

Echocardiography

Echocardiographyis a valuable diagnostic tool, especially inpatientswithculturenegativeendocarditis. Theinvesti­ gation identifies complications like ruptured chordae, perforated cusps and flail cusps resulting from endo­ carditis. Vegetationsmore than 2 mmcan be identified on echocardiography, but its sensitivity is dependent on the site ofinvolvement.Foraorticandmitralvalves,thesensi­

tivityismorethan90%,whilefortricuspidandpulmonary I valves it is 70%. The presence of vegetations has high

negativeaswellaspositivepredictivevalueforconfirming the diagnosis of infective endocarditis. However, the procedure is highly operator dependent. Limitations of echocardiography can be overcome by transesophageal echocardiography, especially in patients with prosthetic valve endocarditis and if valve ring abscess is suspected.

Complications

Damage to valve cusps or perforation, rupture of chordae tendinae result in acute regurgitant lesions causing hemodynamic deterioration. Migration of vegetations may result in embolic neurological deficit, renal infarcts with hematuria, mesenteric infarct and melena, loss of fingers or toes due to obstruction of blood supply. Damage to the vasa vasorumof blood vessels dueto vasculitis may result in theformationofmycoticaneurysmsthatcanruptureand resultinmassivebleeding.Thekidneyssufferinmanyways in endocarditis. They may have embolic infarct with hematuria. There may be focal or diffuse membrano­ proliferative glomerulonephritis resulting in albuminuria and microscopic hematuria. The finding of IgG, IgM and complement deposits on the glomerular basement membrane indicate thatitisanimmune complexnephritis. Renal insufficiency tends to appear beyond three weeks of the onset of endocarditis and is progressive until the endocarditisis cured; hematuria can persist for three to six months. Evenadvancedrenal insufficiencytends toregress and renal function returns to normalafter the endocarditis has been cured. Hence, presence of mildto moderate renal insufficiency should not be viewed as a poor prognostic sign.

Treatment

The main principles in management consist of:

(i) identification of organism; (ii) finding out its antibiotic sensitivity; and (iii) prompt, appropriate and prolonged

antimicrobial treatment to cure and prevent relapse. If the bloodculture is positive the choice of antibiotics is dictated by the antibiotic sensitivity. If the culture is negative empirical therapy covering a wide range of organisms is necessary. Iftheculture is positive,theculture plate should not be discarded. After starting the antibiotic treatment, patient'sserum diluted to 1:8 parts or more should be used to determine if it inhibits the growth of the organism in subculture, to indicatethe efficacy of treatment.Common organisms causing endocarditis, antibiotic of choice and duration of treatment is shown in Table 15.18.

Fungal endocarditis. Fungal endocarditis is very resistant to treatment. The patient should recieve amphotericin B combined with 5-flucytosine if it is sensitive to both. After two to three weeks the patient should be operated to remove the fungal mass with the valve. The antifungal agents should be continued postoperatively for a minimum period of 6 weeks. The dose of amphotericin B is 1.0 mg/kg/day (maximum 1.5 mg/kg/day) intra­ venously and flucytosine 50 to 150 mg/kg/daygivenin 4 divided doses orally. Relapse following apparently successful treatment can occur even up to two years.

Culture negative endocarditis. Patients with culture negative endocarditis need to be treated empirically. The choice of treatment is dictated by circumstances anticipating the most likely organism. If the patient seeks help late and has significant renal insufficiency the treatment has to be modified.

Prophylaxsi

There have been major changes in the recommendations for prevention of endocarditis patients with congenital heart defects such as ventricular septal defect, bicommis­ sural aortic valve and valvar pulmonary stenosis, do not routinely require prophylaxis. According to the new guidelines of the American Heart Association, since the absolute lifetime risk of endocarditis is small, prophylaxis is only recommended for patients with conditions associated with increased risk of adverse outcome from endocarditis (Table 15.19).

The focus of prophylaxis has shifted from prophylactic antibiotics for a dental procedure to the prevention of dental caries, which reduces the incidence of bacteremia

Table 15.19: Conditions where antibiotic prophylaxis is definitely recommended

Prosthetic cardiac valve or use of prosthetic material for valve repair

Past history of infective endocarditis

Unrepaired cyanotic heart disease, including palliative shunts and conduits

During first 6 months following complete repair of congenital heart disease by surgery or catheter intervention using prosthetic material or device

Repaired congenital heart disease with residual defects at or adjacent to the site of repair

Cardiac transplantation recipients with cardiac valvulopathy

from daily activities and is therefore, more important. These guidelines need validation in developing countries where oral hygiene is unsatisfactory and regular dental health screening is not pursued avidly.

The antibiotic recommendations for those who need prophylaxis are as follows:

Dental treatment

a.Penicillin V 2 g given orally on an empty stomach 1 hr before dental treatment, followed by 0.5 g every 6 hr for 3 days, or

b.Crystalline penicillin G 1,000,000 U mixed with 600,000 U of procaine penicillin 30-60minbefore dental treatment, followed by oral penicillin as above, or

c.Single dose of amoxicillin 50 mg/kg orally 1 hr before the procedure.

d.Patients with prosthetic heart valves: Injectable penicillin with streptomycin or gentamicin IM 1 hr before the procedure

Genitourinary and gastrointestinal procedures

•Amoxicillin 25 mg/kg by mouth 1 hr before, with gentamicin 2mg/kg IM 30 min before procedure; both are repeated at least for 2 more doses after the procedure

•Gastrointestinal surgery: Add metronidazole

Infective endocarditis is a life threatening disease with significant mortality and morbidity. Thetreatingphysician should advise patients and parents regarding prevention of endocarditis. The maintenance of good oral hygiene is

encouraged. Careful attention to prophylaxis on the longterm is useful in preventing relapses.

Suggested Reading

Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective en­ docarditis. Guidelines from American Heart Association: A guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Car­ diovascular Surgery and Anesthesia. Circulation 2007;116(15): 1736-54

MYOCARDIAL DISEASES

Myocarditis

Myocarditis usually viral infections, including ECHO, Coxsackie B, rubella, herpes and influenza viruses. Diphtheritic myocarditis is occasionally noted in South Asia. Thepresentationmay be abrupt, with cardiovascular collapse, or insidious development of heart failure. Arrhythmiasandconductiondisturbancesmaybepresent. Examination shows cardiac enlargement, tachycardia, muffled heart sounds and features of congestive cardiac failure. The electrocardiogram shows low voltages, and nonspecific ST-T changes. Chest X-ray reveals cardiac enlargement with pulmonary venous congestion.

Treatment includes management of congestive failure. Digoxin should be used cautiously, preferably in half to three quarters of the standard dose. Steroids are of uncertain value and perhaps should be avoided in the

Disorders of Cardiovascular System -

acute phase of virernia. ACEinhibitors are a useful adjunct to therapy. The utility of IV immunoglobulin infusion is not proven.

Cardiomyopathies

The term cardiomyopathy is an intrinsic disease of the

myocardium which is not associated with a structural deformity of the heart. It is considered primary cardio­ myopathy when the etiology is unknown, and secondary,

ifthemyocardialdiseaseisattributedto asystemicdisease. Myocardial diseases are classified clinically as (i) dilated, (ii) restrictive, and (iii) hypertrophic type of cardio­ myopathy.

A significant proportion of patients have correctible causes of left ventricular dysfunction that mimics dilated cardiomyopathy (Table 15.20). A diagnosis of idiopathic dilated cardiomyopathy can only be made after these causes are excluded.

Dilated Cardiomyopathy (DCM)

Dilated cardiomyopathy is the commonest form of myocardial disease. The onset of cardiac failure may be acute or insidious. Cardiomegaly and S3 gallop are pre­ sent. Murmur of MR and uncommonly, that of tricuspid regurgitation, may be present. The patients are prone to embolic phenomena. The electrocardiogram may show non-specific ST and T changes with or without left ventri­ cular hypertrophy, conduction disturbances, arrhythmias or pseudo-infarction pattern. Chest X-ray shows cardio-

Patients with predominantleft sidedinvolvement have symptoms of dyspnea, orthopnea, hemoptysis and embolic phenomena. On examination, there is cardio­ megaly with or without findings of MR. Cardiac output is low and there are features of pulmonary venous and arterial hypertension. With predominant right-sided involvement, patients present with fatigue, pedal edema and ascites. There is cardiomegaly with prominentcardiac pulsations in the second, third and fourth left interspace from a dilated right ventricular outflow. S3 gallop and tricuspid regurgitation murmur may be present. The electrocardiogram and chest X-ray do not show-specific changes. Treatment consists of decongestive therapy. Decortication or stripping of the endocardiumwith mitral valve replacement has been tried with variable success.

Restrictive cardiomyopathy of other uncommon varieties is characterized by a combination of features of left and right-sided failure with a normal sized heart. Clinically, or evenfollowing cardiac catheterization, it may be difficult to distinguish it from constrictive pericarditis. However, children with restrictive cardiomyopathy tend to have dominant left sided involvement and dispropor­ tionate pulmonary hypertension. Echocardiogram can be useful in excluding constrictive pericarditis. Treatment consists in bed rest and anticongestive therapy.

Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy may occur (a) without outflow obstruction, or (b) with outflow obstruction. Obstructive cardiomyopathy is also known as idiopathic hypertrophic subaortic stenosis (IHSS) or asymmetrical septal hypertrophy (ASH) or hypertrophic obstructive cardiomyopathy (HOCM).

Hypertrophic cardiomyopathy with obstruction (HOCM) is uncommon in children. Pathologically there is asymmetrical hypertrophy of the ventricular septum. The free walls of the left and right ventricles are hypertrophied to a lesser extent. The ventricular septum bulges into the left ventricle, and the malaligned anterior mitral valve leaflet causes obstruction in the left ventricular outflow during systole. Uncommonly, there is right ventricular outflow obstruction as well. The abnormally oriented mitral valve may regurgitate.

Patients usually present with exertional dyspnea, anginal chest pain, palpitationandsyncope; sudden death can occur. The pulse has a sharp upstroke with a bisferiens character. The apex beat is forcible or heaving. The fourth sound may be palpable at the apex. Double or triple apical impulse may be present. The second sound may be normally split, single or paradoxically split, depending on the severity of the left ventricular outflow obstruction. An ejection systolic murmur of varying intensity is heard at left sternal edge. A pansystolic murmur or MR and a fourth sound may be heard at the apex.

The ejection systolic murmur increases in intensity with maneuvers which increase the myocardial contractility or decreasethevolumeoftheleftventricle.Themurmurdecrea­ sesinintensitywithproceduresthatincreaseleftventricular volume or decrease the myocardial contractility. Thus, sudden squatting tends to decrease the intensity of the murmurwhereasstandingupright fromsittingpositionby decreasing the venous return tends to decrease the left ventricular size and increases the intensity of the ejection systolic murmur. The electrocardiogram shows left ventricularhypertrophy,withorwithoutischemicchanges. Prominent initial R in right precordial leads and deep Q

wavesintheleftchestleadsmaybepresentwithorwithout a WPW pattern. Echocardiogram shows disproportionate hypertrophy of the ventricular septum, systolic anterior motion(SAM)of theanteriorleafletof themitralvalveand mid-systolic closure of the aortic valve.

Hypertrophic cardiomyopathy often has an autosomal dominant pattern of inheritance with a variable but high degree of penetrance. Mutations in beta-myosin, troponin T and alpha-tropomyosin gene are believed to be res­ ponsible. Magnetic resonance imaging may help identify myocardial fibrosis and indirectly help in identifying patients at risk of sudden cardiac death. Noonan syndrome is associated with myocardial hypertrophy and ASH.

Patients with hypertrophic obstructive cardiomyopathy should have a 24 hr Holter to document the presence of arrhythmias. The effect of exercise on the rhythm should be ascertained. These patients should avoid strenuous games and exercise. Digitalis and other inotropic drugs as well as diuretics and nitrates are contraindicated in these patients.

The prognosis is variable; young age of onset predicts poor prognosis. The disease may be progressive and sudden death may occur in spite of medical and/or surgical treatment. Beta-blockers decrease themyocardial contractility and thus decrease the obstruction.

PERICARDIAL DISEASES

Inflammatory diseases of the pericardium may present as acute dry pericarditis, pericarditis with effusion or chronic constrictive pericarditis (Table 15.21).

Acute Pericarditis

Acute pericardia! inflammation causes precordial pain, which may be dull, sharp or stabbing in character. Occasionally, the pain may be felt over the neck and shoulder and may worsen on lying down. The child becomes dyspneic and has cough. The pattern of fever and toxemia depends on the etiology. The bedside diagnostic physical sign is the presence of pericardia! friction rub, which is a rough scratchy sound, with three components, a systolic, diastolic and a presystolic scratch. It can be heard anywhere over the precordium, is unrela­ ted to the respiratory cycle and increases on pressing the

Table 15.21: Etiology of pericardia! diseases

chest piece of stethoscope over the precordium. The electrocardiogram shows generalized ST elevation in the initial stages. Later the ST segment becomes isoelectric and T waves become inverted. Still later, the ST segment may be depressed. The thoracic roentgenogram is unremarkable at this stage.

If effusion develops, the cardiac silhouette increases in size. The heart sounds become muffled and evidence of peripheral congestion in theform ofraisedjugular venous pressure, hepatomegaly and edema may develop. The pericardia! friction rub may persist or disappear. If the fluid accumulates rapidly, there is marked interference with cardiac filling resulting in features of cardiac tamponade such as: (i) rising jugular venous pressure;

(ii)paradoxical inspiratory filling of the neck veins;

(iii)increasing heart rate; (iv) falling pulse pressure; and

(v)appearanceofpulsusparadoxus. The electrocardiogram shows non-specific generalized ST and T changes with low voltagetracings. The chest X-ray shows cardiomegaly with smooth outline and blunting of the cardiohepatic angle. The lung fields are clear. Echocardiogram shows an echo-free space behind the posterior left ventricular wall.

Evidence of right atrial or right ventricular diastolic collapseindicatesa hemodynamically significant effusion. Pericardiocentesis should be done to determine the etiology aswellasto relieve cardiac tamponade if present. Treatment will depend on the etiology. Surgical drainage is indicated when pyopericardium is suspected.

Chronic Constrictive Pericarditis

Constrictivepericarditisis not uncommon in our country, tuberculousinfectionand, less commonly, often following a pyogenic pericarditis. Fibrous thickening of both layers of the pericardium encases the heart and restricts filling of both the ventricles equally; calcification is rare in childhood. The myocardium is not involvedinitially, but the fibrous process later infiltrates the myocardium, making surgical correction difficult. Dyspnea, fatigue and progressive enlargement of the abdomen are common.

Jugular venous pressure is always elevated with equally prominent 'a' and 'v' waves and a prominent 'y' descent. Inspiratory filling of neck veins (Kussmaul sign) is seen in about one-half. Liver is enlarged and pulsatile; ascites with unilateral or bilateral pleural effusion is common. Splenomegaly may also be present. Pulse is fast and of low volume and pulsus paradoxus may be present. The precordium is quiet with a normal sized heart. First and second sounds are normal. An early third heart sound (pericardia! knock) is commonly heard. The EKG shows low voltage in 75% patientsand non-specific ST-T changes in all cases. Normal electrocardiogram is against the diagnosis ofconstrictive pericarditis. Occasionally, there is right axis deviation or right ventricular hypertrophy pattern.

The chest X-ray shows normal sized heart with ragged or shaggy borders and prominent superior vena cava

shadow merging with the right atrial margin. The lungs may show pleural effusion and plate atelectasis. Fluoroscopy shows reduced cardiac pulsations and may help reveal pericardia! calcification. Hemodynamic studiesreveal elevation of right atrialmeanpressure, right ventricular end-diastolic pressure, pulmonary artery diastolic pressure and the pulmonary artery wedge pressures, which are identical. The right ventricular end­ diastolic pressure is more than one-third of the systolic pressure. The cardiac index may be normal or reduced, but the stroke volume is low. In some cases, acute digitalizationmayimprove the hemodynamics indicating presence of myocardial dysfunction.

Surgical decortication of the pericardium results in normalization of the hemodynamic abnormalities in most cases. Some casesof long-standingconstrictivepericarditis with myocardial dysfunction may improve slowly or have residual myocardial dysfunction. Except post-pyogenic pericarditis, most patients in India receive 6-weeks' therapy with antitubercular agents before surgery, since majority of cases are post-tuberculous. A full course of antitubercular treatment follows pericardiectomy.

SYSTEMIC HYPERTENSION

Essential(primary)hypertensionis themost commonform of hypertension in adults and is recognized more often in adolescents than in younger children. Systemic hypertension is rare in infants and young children, but when present, it is usually due to an underlying disease (secondary hypertension). With age, the prevalence of essential hypertension increases and becomes the leading cause of elevated blood pressure in adolescents. Approximately 4% of children and adolescents have hypertension and 10% have pre-hypertension.

Etiopathogenesis

The etiology of essential hypertension is multifactorial. Obesity,insulinresistance, activation of sympathetic ner­ vous system, disorders in sodium homeostasis and renin­ angiotensinsystem, vascularsmoothmusclestructure and reactivity, uric acid levels, genetic factors and fetal programminghavebeenimplicated.Primaryhypertension is often associated with a family history of hypertension.

Approximately 90% of secondary hypertension in children are due to renal or renovascular abnormalities. The majorrenalcausesincludechronic glomerulonephritis, reflux or obstructive nephropathy, polycystic or dysplastic renal diseases andrenovascular hypertension. Coarctation of the aorta and Takayasu aortoarteritis are leading vascular causes. Hyperthyroidism, hyperparathyroidism, congenital adrenal hyperplasia, Cushing syndrome, primary aldosteronism, pheochromocytoma and neuroblastoma are endocrine causes of secondary hypertension in children.

Certain conditions can result in transient or intermittent hypertension. Renal causes include postinfectious

Disorders of Cardiovascular System -

glomerulonephritis, rapidly progressive (crescentic) glomerulonephritis, Henoch-Schonlein purpura, hemo­ lytic uremic syndrome, acute tubular necrosis, and renal trauma. Raised intracranial pressure, Guillain-Barre syndrome, burns, Stevens-Johnson syndrome, porphyria, poliomyelitis, encephalitis, drugs (e.g. sympathomimetic agents, steroids, cyclosporine), heavymetalpoisoning (e.g. lead, mercury) and vitamin D intoxication result in elevations of blood pressure.

Definition and Staging

The Fourth Report on the diagnosis, evaluation and treatment of high blood pressure in children and adoles­ cents provided normative data on distribution of blood pressure in healthy children. Hypertension is defined as average systolic blood pressure (SBP) and/or diastolic bloodpressure (DBP) that is 95th percentile forage, sex and heighton 3 occasions. Prehypertension is defined as SBP or DBP thatare 90thpercentile but <95thpercentile. Adolescents having blood pressure between 120/80 mm Hg and the 95th percentile are also considered as having prehypertension. Children with blood pressure between the 95th percentile and 99th percentile plus 5 mm Hg are classified as stage I hypertension and children with blood pressureabovethe99thpercentileplus5mmHghavestage II hypertension. Figures 15.46 and 15.47A and B indicate bloodpressurecut off forstage Iandstage IIhypertension in girls and boys with stature at median for age.

Measurement of Blood Pressure

Blood pressure in children can be measured by auscul­ tation, palpation, oscillometry and Doppler ultrasound. Auscultation or oscillometric determination is preferred. Children and adolescents should be subjected to blood pressuremeasurementonly after a periodof adequate rest (5 to 10 min). Blood pressure should be measured at least twice on each occasion in a child's right arm in the seated position.Thestethoscopeis placedover the brachialartery pulse, proximal and medial to the cubital fossa and below the bottom edge of the cuff. An appropriate selection of cuffs is necessary (Table 15.22). Cuffs should have a

Table 15.22: Recommended dimensions for blood pressure cuff bladders

Maximum arm circumference is calculated such that the largest arm would still allow bladder to encircle arm by at least 80% (Adapted from Fourth Task Force report)