Cardiac Emergencies

Isabel Araujo Barata, MS, MD

KEYWORDS

� Cardiac emergencies � Pediatrics � Cardiac disease

KEY POINTS

� The diagnosis and management of pediatric cardiac emergencies can be challenging andcomplicated. Early presentations are usually the result of ductal-dependent lesions andappear with cyanosis and shock.

� Later presentations are the result of volume overload or pump failure and present withsigns of congestive heart failure (CHF).

� Acquired diseases also present as CHF or arrhythmias.

Cardiac disease is uncommon in childhood, but a delay in diagnosis may lead todevastating consequences. In addition, pediatric cardiology has expanded greatlyin the last decade, with new surgeries and procedures for many congenital cardiacconditions, which clinicians need to be familiar with to manage these children.Cardiac disease in infancy and childhood can be divided into structural disease,

conduction abnormalities, and acquired illnesses. Cardiac lesions can be a combina-tion of many defects; however, structural congenital heart disease (CHD) can be clin-ically divided into cyanotic and acyanotic categories. The surgical repair of CHDcontinues to progress, with some lesions now repaired in the neonatal period, andmost lesions repaired in the first couple of months of life. However, patients may stillappear in the emergency department before palliative surgery, or corrective surgery;these patients can be on multiple medications and require coordinated managementwith the pediatric cardiologist. Patients may also show postoperative complicationssuch as a dysrhythmia, postpericardiotomy syndrome, or shunt stenosis. Conductionabnormalities can be congenital, the result of a new-onset illness or after a cardiacprocedure. Acquired heart disease includes myocarditis, pericarditis, endocarditis,Kawasaki disease (KD), and cardiomyopathies. Timely identification, management,and stabilization of these patients are important goals. This article reviews the morecommon pediatric cardiac emergencies and their management.

CYANOTIC HEART DISEASE

There are 5 well-known cyanotic congenital heart lesions (also known as the TerribleTs). They are tetralogy of Fallot (TOF), transposition of the great arteries (TGA), total

Pediatric EmergencyMedicine,NorthShoreUniversityHospital, 300CommunityDrive,Manhasset,NY 11030, USAE-mail address: ibarata@aol.com

Emerg Med Clin N Am 31 (2013) 677–704http://dx.doi.org/10.1016/j.emc.2013.04.007 emed.theclinics.com0733-8627/13/$ – see front matter � 2013 Elsevier Inc. All rights reserved.

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anomalous pulmonary venous return (TAPVR), tricuspid atresia (TA), and truncusarteriosus.

TOF

IncidenceAbout 3% to 5% of all infants with a CHD have TOF, with males and females beingaffected equally.1

Anatomy/physiologyTOF consists of 4 basic lesions; a large ventricular septal defect (VSD), right ventricularoutflow obstruction (from pulmonic stenosis), an overriding aorta, and right ventricularhypertrophy (RVH). The range of physiology seen with TOF is diverse. The extent ofobstruction of the right ventricular outflow track determines the amount of cyanosispresent in the patient. Systolic pressures are equally balanced in the right and leftventricle because of the nonrestrictive VSD. There is a left-to-right shunt, a bidirec-tional shunt, or a right-to-left shunt, depending on the extent of the right ventricularoutflow tract obstruction. If the pulmonic stenosis is severe, there is a right-to-leftshunt, with subsequent cyanosis and decreased pulmonary blood flow. If there ismild pulmonic stenosis, a left-to-right shunt occurs, resulting in an acyanotic TOF.2

Clinical presentationPatients usually present as neonates with cyanosis, but typically without respiratorydistress. In addition to cyanosis, the physical examination may show a systolic thrillat the lower and middle left sternal border. A loud and single S2, an aortic ejectionclick, and a loud grade 3 to 5/6 systolic ejection murmur in the middle to lower left ster-nal border are also found. A continuous patent ductus arteriosus (PDA) murmur mayalso be present.2 Once the diagnosis is suspected, an electrocardiogram (ECG) andchest radiograph should be obtained. The classic ECG shows right axis deviation(RAD) and RVH with large R waves in the anterior precordial leads and large S wavesin the lateral leads.3 The chest radiograph, of an infant with a cyanotic TOF, shows aboot-shaped cardiac silhouette secondary to upward displacement of the right ven-tricular apex caused by RVH, and narrowing of the mediastinal shadow caused bythe hypoplastic pulmonary outflow tract. The heart size is normal, with decreased pul-monary vascular markings (Fig. 1). Infants with acyanotic TOF have a radiograph

Fig. 1. TOF. Boot-shaped cardiac silhouette secondary to upward displacement of the rightventricular apex caused by RVH, and narrowing of the mediastinal shadow caused by thehypoplastic pulmonary outflow tract. (Courtesy of Mark Bittman, MD, New Hyde Park, NY.)

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similar to that of moderate VSDs and show cardiomegaly as well as increased pulmo-nary vascular markings.2 Diagnosis is confirmed by echocardiography.

ManagementFirst, supplemental oxygen should be given through a humidified system by face maskor nasal cannula. Fluid resuscitation may be given initially, because the child may beintravascularly volumedepleted (cautious 5–10mL/kg aliquots assessing response aftereach bolus). However, neonates who present with ductal-dependent flow to the lungsneed intravenous (IV) prostaglandin E1 (PGE1) to maintain ductal patency until surgicalintervention. Decreasing pulmonary vascular resistance helps in left-to-right shuntingand increases pulmonary blood flow. The initial dose of PGE1 is 0.05 mg/kg/min. Apneaand hypotension are potential side effects of PGE1, so airway management is essential.If possible, consultation with pediatric cardiology as well as the critical (neonatal or pe-diatric) care staff is beneficial.Initial surgical intervention may be palliative, such as a Blalock-Taussig shunt for pa-

tients with significant comorbidities and contraindications to open heart surgery. Thisshunt creates a systemic-to-pulmonary arterial shunt between the subclavian arteryand the ipsilateral pulmonary artery. The modified Blalock-Taussig shunt uses aGore-Tex shunt and requires less dissection, is not dependent on the vessel length,and has decreased shunt failure. The Rastelli procedure is performed in older patients,and is used in severe TOF with significant right ventricular outflow tract obstruction.There is patch closure of the VSD, with the placement of a conduit from the rightventricle to the pulmonary artery.4,5 The trend is towards neonatal repair.6

Cyanotic or hypoxemic episodes (tet spells) are seen in patients with TOF; hyper-pnea, irritability, and increasing cyanosis along with a decreased intensity of the un-derlying heart murmur. A decrease in systemic vascular resistance or increasedresistance to the right ventricular outflow tract increases right-to-left shunting, causinghyperpnea and, then, increased systemic venous return causes increased right-to-leftshunting through the VSD. To manage a tet spell the patient should be placed in aknee-chest position and receive oxygen, volume expansion, sedation with morphineor ketamine, and, if needed, vasopressors, such as phenylephrine, to increase sys-temic vascular resistance and decrease the relative ratio between resistance to pul-monary and systemic output.2 Oxygen may or may not help because the problem isto improve pulmonary blood flow. Morphine sulfate (0.1–0.2 mg/kg subcutaneouslyor intramuscularly) stops the hyperpnea. Ketamine (1–3 mg/kg IV) can also increasesystemic vascular resistance and provide sedation. Propanolol (0.01–0.2 mg/kg IVover 5 minutes) can be beneficial. Phenylephrine (0.02 mg/kg IV) can help byincreasing systemic vascular resistance.

TGA

IncidenceTGA represents around 5% to 8% of CHD and is the most common cyanotic heartlesion in the newborn period.7

Anatomy/physiologyIn this anomaly, the aorta originates from the morphologic right ventricle, and the mainpulmonary artery arises in the morphologic left ventricle. Complete TGA is also knownas d-TGA; the d- refers to the dextroposition of the bulboventricular loop. The aortaalso tends to be on the right and anterior, and the great arteries are parallel ratherthan crossing as they do in the normal heart. Because the systemic and pulmonarycirculations run in parallel, presence of a VSD, atrial septal defect (ASD), or PDA isessential to survival, because the mixing of the circulations is the only way of providing

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oxygenated blood to the systemic system.8 Associated lesions are VSD found inapproximately 20% to 40% of patients, pulmonary outflow tract obstruction, and,less commonly, approximately 5% coarctation of the aorta.9

Clinical presentationIf the interventricular septum is intact, these patients are the critically ill. If circulatorymixing is occurring via a PDA, physiologic closure of the ductus causes abruptcyanosis and clinical deterioration. If there is a VSD or large PDA, the neonate is notso cyanotic but presents with dyspnea and feeding difficulties with congestive heartfailure (CHF) and obstructive pulmonary disease.8 On cardiac examination a loud, sin-gle S2 is present as well as a systolic murmur if there is a VSD. The ECG shows RADand RVH. In an infant with classic TGA, the chest radiograph shows an egg-shapedheart with a narrow mediastinum, in addition to cardiomegaly with increased pulmo-nary vascular markings (Fig. 2). The echocardiogram shows 2 circular structuresinstead of the circle and sausage pattern of normal great arteries.8

ManagementThe severe arterial hypoxemia does not respond to the administration of oxygen.These patients respond well to PGE1 infusion. Neonates with a VSD or large PDAare not so cyanotic but present with CHF and obstructive pulmonary disease. Earlyconsultation and involvement of both pediatric cardiology and the critical (neonatalor pediatric) care staff is beneficial. Initial surgical intervention for cyanotic babiesmay be a percutaneous Rashkind atrial balloon septostomy to create an ASD, whichmay dramatically improve oxygenation until definitive surgery can be performed.10

Definitive surgery is the arterial switch that corrects TGA at the great artery level.The aortic trunk is attached to the left ventricle and the pulmonic trunk is attachedto the right ventricle.11

Fig. 2. d-Transposition of great vessels with VSD. Cardiomegaly with a cardiac contour clas-sically described as appearing like an egg on a string. (Courtesy of Dr Hani Al Salam,Radiopaedia.org.)

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TAPVR

IncidenceTAPVR represents around 1.5% of CHD and has an incidence of 6.8/100,000 livebirths.12

Anatomy/physiologyTAPVR is a congenital lesion, in which the pulmonary veins that normally bring oxygen-ated blood from the lungs to the left atrium anomalously drain into another structurethan the left atrium. TAPVR is generally divided into 4 groups, depending on wherethe pulmonary veins drain. In the supracardiac type (50%), the common pulmonaryvein attaches to the superior vena cava. In the cardiac type (20%), the common pulmo-nary vein empties into the coronary sinus. In the infracardiac/subdiaphragmatic type(20%), the common pulmonary vein empties into the portal vein, ductus venosus, he-patic vein, or inferior vena cava. A mixed type is seen in 10% of the lesions, which is acombination of any of the types.13 Although this lesion represents a left-to-right shunt,a right-to-left intracardiac shunt must occur to provide mixing of blood. An ASD orpatent foramen ovale is necessary for mixing of the blood.14,15

Clinical presentationThe clinical course is dependent on the obstruction to the flow of the anomalous pul-monary venous return or not. If there is obstruction to pulmonary venous return, thereis significant cyanosis and respiratory distress. With the blood from both the pulmo-nary and systemic circulations pumped by the right ventricle, there can be volumeoverload, with subsequent right ventricular and atrial enlargement. There can be min-imal cardiac examination findings, aside from a loud and single S2 and gallop rhythm.A murmur is usually not found. The ECG typically shows RAD and RVH, and the chestradiograph has a normal heart silhouette, with lung fields consistent with pulmonaryedema.16 If there is no obstruction to pulmonary venous return, there is minimal desa-turation of the systemic blood; patients present with a history of frequent pneumoniasand growth difficulties. In addition to slight cyanosis, patients present with signs ofCHF, including tachypnea, tachycardia, and hepatomegaly.16 There is a hyperactiveright ventricular impulse, with a split and fixed S2. A grade 2 to 3/6 systolic ejectionmurmur is at the upper left sternal border, with a middiastolic rumble at the left lowersternal border. The ECG shows RAD, RVH, and right atrial enlargement. Chest radiog-raphy shows significant cardiomegaly, with increased pulmonary vascular markings.The characteristic snowman sign is found in infants older than 4 months (Fig. 3).16

Fig. 3. TAPVR (supracardiac total anomalous pulmonary venous connection). Snowman signsometimes also referred to as a figure-of-8 sign. (Courtesy of Dr Praveen Jha, Radiopaedia.org.)

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ManagementUnlike many cyanotic lesions in the newborn, management is not ductal dependentand PGE1 is not indicated. Surgical correction is the first line of treatment, and medicalmanagement is to ensure proper acid-base balance, and diuretics if there is CHF.Airway management should take precedence because mechanical ventilation canprevent further respiratory decompensation. Inotropic assistance is important. Dopa-mine can be started at a continuous infusion at 5 to 10 mg/kg/min. Dobutamine can bestarted at the same dosing. However, dobutamine should be used with caution in pa-tients younger than 1 year. Amrinone at 0.5 mg/kg IV over 3 minutes and milrinoneloading dose of 10 to 50 mg/kg IV over 10 minutes could be another adjunct secondaryto their inotropic and vasodilator properties.17 Pulmonary vasodilators are usually notindicated, because they could exacerbate CHF.

TA

IncidenceTA represents the third most common cause of cyanotic CHD (1%–2% in infancy).18

Anatomy/physiologyFor this congenital cardiac condition, there is no tricuspid valve and underdevelop-ment of the right ventricle and pulmonary artery,19 resulting in decreased pulmonaryblood flow. Because there is complete separation of the right atrium and ventricle,to empty, the right atrium needs a right-to-left shunt, so an ASD, VSD, or PDA isnecessary for survival. Usually patients are divided into groups: type I, those withoutTGA; type II, those with transposition; and type III, those with other complex anoma-lies. The great arteries are transposed in 30% of cases, with a VSD and no pulmonicstenosis. In 50% of cases, there is normal artery anatomy, with a small VSD and pul-monic stenosis. This is a serious lesion that has 50% mortality by 6 months of agewithout surgical intervention.20 There is right atrial dilatation and hypertrophy, becauseall systemic venous return is shunted from the right atrium to the left atrium. Enlarge-ment of the left atrium and ventricle occurs because of the work of handling both sys-temic and pulmonary returns.

Clinical presentationAll patients with TA have some degree of arterial hypoxemia. The amount ofcyanosis is inversely related to the amount of pulmonary blood flow. Severecyanosis, tachypnea, and poor feeding are common presentations. On cardiac ex-amination, there is a single S2 and the murmur is a grade 2 to 3/6 systolic regurgi-tant murmur from the VSD and is heard best at the left lower sternal border. Therecan also be a continuous murmur of a PDA. Hepatomegaly can be found with CHF.The ECG has a superior QRS axis, along with right atrial hypertrophy, left atrial hy-pertrophy (LAH), and left ventricular hypertrophy (LVH). The chest radiograph showsa normal to slight increase in heart size, along with decreased pulmonary vascularmarkings.18

ManagementAirway management should take precedence, because mechanical ventilationcan prevent further respiratory decompensation. The key to dealing with thisductal-dependent lesion is to start IV PGE1. The initial surgical intervention isusually a shunt procedure aimed at improving pulmonary blood flow so thatphysiologic correction by means of a Fontan-Kreutzer procedure may be performedlater.20

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Truncus Arteriosus

IncidenceTruncus arteriosus is an uncommon cardiac abnormality and is seen in less than 1% ofall CHD.21

Anatomy/physiologyIn truncus arteriosus, a single arterial trunk arises from the ventricle via a single arterialvalve to supply the systemic, pulmonary, and coronary circulations. It is also associ-ated with the presence of a VSD, and abnormalities of the coronary arteries.22,23

Clinical presentationThe clinical presentation is dependent on the amount of pulmonary blood flow, whichis in turn dependent on the presence or absence of pulmonary stenosis or the level ofpulmonary arteriolar resistance. With decreased pulmonary blood flow, cyanosis isprevalent. With increased pulmonary blood flow, cyanosis is minimal; however, CHFis more prevalent. The left ventricle has to deal with significant volume overloads. Usu-ally within the first weeks of life, the patient presents with CHF and cyanosis.24 There isa loud regurgitant 2 to 4/6 systolic murmur at the left sternal border, sometimes asso-ciated with a high-pitched diastolic decrescendo murmur or a diastolic rumble. The S2is single and accentuated. The ECG usually shows bilateral ventricular hypertrophy(Fig. 4), and the chest radiograph has cardiomegaly, with increased pulmonaryvascular markings.24

ManagementThe priorities are airway management and starting IV PGE1. Timing of truncus arterio-sus repair continues to be a point of discussion. Some surgeons advocate elective

Fig. 4. Truncus arteriosus. The axis of QRS is 90� (roughly isoelectric in I and positive in aVF).This is a rightward axis. The large QRSs in V1 to V6 meet the voltage criteria for both LVHand RVH. This electrocardiogram shows biventricular hypertrophy.

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repair of truncus arteriosus without major associated cardiac anomalies during the first3 months of life;25,26 others prefer primary neonatal correction.27–29

ACYANOTIC HEART DISEASE

Left-to-right shunt lesions include VSDs, ASDs, PDA, and endocardial cushion de-fects. This group comprises almost 50% of all CHD.30 Left-to-right shunt lesionshave blood shunted from the systemic system into the pulmonary system. CHF resultsfrom chamber enlargement, and increased pulmonary vascular pressures. In theneonate, high pulmonary vascular resistance controls the amounts shunted, butonce pulmonary vascular resistance starts to decrease in the first few weeks of life,pulmonary blood flow and pressures increase.

ASDs

IncidenceASD comprise up to 10% of all CHD.31

Anatomy/physiologyAny opening in the atrial septum is described as an atrial defect. There are manydifferent types of ASD, such as the typical secundum atrial defect, which is most com-mon and usually single; multiple fenestrations of the septum primum; and sinus veno-sus defects. The amount of shunting through a large atrial defect is determined by therelative right and left ventricular (LV) compliance. Early in infancy, the right ventricle isless compliant, and left-to-right shunting is minimal. As patients age, the right ventriclebecomes more compliant and there is increased left-to-right shunt.

Clinical presentationAbout 10% of infants with ASD present with feeding difficulties and failure to gainweight.32 However, most patients are diagnosed later in life, because patientshave nonspecific symptoms, including fatigue and breathlessness. The larger theleft-to-right shunt, the greater the risk of developing long-term complications suchas atrial fibrillation and pulmonary hypertension. Pulmonary hypertension affectsup to 15% of patients with ASD and if not corrected can result in Eisenmenger syn-drome (the pressures reverse and it becomes a right-to-left shunt, with decrease insystemic oxygenation). Another condition associated with ASD is stroke.33 The car-diac examination has a widely split and fixed S2, with a grade 2 to 3/6 systolic ejec-tion murmur at the upper left sternal border, sometimes associated with amiddiastolic rumble. ECG findings include RAD and RVH or right bundle branchblock (RBBB). Chest radiography shows cardiomegaly with increased pulmonaryvascular markings (Fig. 5).34

ManagementSome defects close spontaneously, but larger defects require surgical intervention.The timing of the surgical intervention seems to make a difference because closureafter age 40 years is associated with greater frequency of arrhythmias, in particularatrial fibrillation.35

VSDs

IncidenceVSDs are the most common type of CHD and present in approximately 25% of all CHDcases.36,37

Fig. 5. Atrial septal defect. Cardiomegaly. (Courtesy of Mark Bittman, MD, New Hyde Park,NY.)

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Anatomy/physiologyVentricular defects are single or multiple and are classified by their location in theseptum; the most common are either membranous or muscular. The extent of thedefect determines the degree of cardiac compromise. Large VSDs have volume andpressure overload in the right ventricle as well as volume overload in the left atriumand left ventricle.

Clinical presentationLarge VSDs commonly present with poor weight gain and CHF. Patients with smallVSDs are more likely to be asymptomatic; however, the smaller defects produce alouder systolic murmur. Typical examination shows a grade 2 to 5/6 systolic murmur(holosystolic), heard best at the left lower sternal border. A systolic thrill or diastolicrumble can also be present, with a narrowly split S2. ECG findings vary with thesize of the defect; moderate VSDs show LAH and LVH, larger VSDs have LVH,RVH, and LAH. The chest radiograph also varies based on the size of the defectand may show cardiomegaly as well as increased pulmonary vascular markings(Fig. 6).38

ManagementSurgical closure is recommended for any subpulmonary defects (except for smallones), perimembranous (subcristal) defects, obvious prolapse, and tricuspid valveinvolvement shortly after they are diagnosed, if aortic regurgitation is present butmild closure alone is sufficient. Valvuplasty is necessary if regurgitation is at leastmoderate. Valve replacement is rarely needed, except in older patients. Beyond age15 years, if regurgitation is mild at most, shunting minimal, and the patient stable,continued medical observation seems reasonable. Sometimes, the additional lesionsare the major indication for surgery in these patients.38

Fig. 6. VSD. Cardiomegaly and pulmonary vascular congestion. (Courtesy of MarkBittman, MD, New Hyde Park, NY.)

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PDA

IncidencePDA is seen in 10% of all CHD. It is the second most common congenital heart defectin adults, making up 10% to 15% of all CHD in adults. There is a female/male ratioof 2:1.30

Anatomy/physiologyIn patients with PDA, the ductus does not close as it ordinarily would. The ductus con-nects the descending aorta at the level of the subclavian artery to the left pulmonaryartery. In healthy patients, the ductus arteriosus functionally closes within hours afterbirth and then completely seals around 3 weeks of age, usually at the pulmonary end,often leaving behind a remnant on the aorta called ligamentum arteriosum. In prema-ture infants, the process of ductal closure is the same but is delayed, sometimes forweeks. The incidence of persistent patency of the ductus well past infancy in patientswho were premature is greater than it is in the normal population.39 The degree of theleft-to-right shunting is dependent on the lesion length and diameter and pulmonaryvascular resistance.

Clinical presentationCHF is present if the PDA is large. Physical examination is remarkable for a grade 1 to4/6 continuous machinery like murmur, heard best at the left upper sternal border. Adiastolic rumble can also be present as well as bounding peripheral pulses. The ECG isnormal when there is a small PDA; it can show LVH and RVH and pulmonary hyperten-sion in large PDAs. Chest radiography shows cardiomegaly and increased pulmonaryvascular markings.39

ManagementMost experts believe that it should be closed either surgically or percutaneously toprevent endarteritis as well as to remove excess flow to the pulmonary circulation.39

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Endocardial Cushion Defects

IncidenceEndocardial cushion defects represent around 3% of CHD, and almost two-thirdshave the complete form. Down syndrome is strongly associated with the completeform of endocardial cushion defects.30

Anatomy/physiologyWhen the endocardial cushion does not develop properly, there are defects to theatrial septum, the ventricular septum, and the atrioventricular (AV) valves. Completedefects involve the entire endocardial cushion and have atrial and ventricular septallesions and a common AV valve. Incomplete or partial defects have atrial involvement,with an intact ventricular septum. There can also be variations of both complete andincomplete lesions.40

Clinical presentationThe presentation for endocardial cushion defects is similar to ventricular or atrial de-fects or both, with the added possibility of AV valvular regurgitation. A history of failureto thrive and multiple respiratory tract infections is common. Left-to-right shunting isdirectly dependent on the extent of the defects, with complete lesions presenting withCHF early from volume overload in both the left and right ventricles. Cardiac examina-tion is remarkable for a hyperactive precordium, a systolic thrill, a loud holosystolicregurgitant murmur, and a loud and split S2. The ECG shows a superior QRS axis,with RVH, RBBB, and LVH, along with a prolonged PR interval.40

COARCTATION OF THE AORTAIncidence

Coarctation of the aorta represents 8% to 10% of CHD and is seen in males in a 2:1ratio.41

Anatomy/Physiology

There is congenital narrowing of the descending aorta, which occurs before, at thelevel of, or after the origin of the left subclavian artery. The extent of the symptomsis dependent on the degree of narrowing, the length of the narrowing, and the pres-ence of other cardiac defects. For a critical coarctation, the PDA is able to temporarilynegate the negative effects of the coarctation. When the PDA eventually closes, thedevelopment of pulmonary hypertension and subsequent pulmonary venous conges-tion leads to CHF.42

Clinical Presentation

Neonates with critical coarctation often present with shock and metabolic acidosis.The presence of decreased pulses in the lower extremities, compared with the upperextremities, is key in the diagnosis of a coarctation. Disparities between right upperextremity and lower extremity blood pressures and pulse oximeter readings aid inthe diagnosis. However, if the patient is in significant shock, pressures can bedecreased everywhere.42 When presenting in CHF, there is a loud gallop, a murmurmay or not be present, and pulses are weak. The ECG shows RVH or RBBB(Fig. 7). Chest radiography shows cardiomegaly as well as pulmonary edema (Figs.8 and 9). In older children, the appearance of notching of the first rib, also known asthe 3 sign, may be present.42

Fig. 7. Coarctation of the aorta ECG. Right axis; right atrial enlargement.

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Management

The main aim of initial management is to stabilize the infant’s condition so that a diag-nosis can be confirmed and a treatment plan can be made. Initial management is tosecure ductal patency with PGE1 infusion. The mainstay is surgical correction withresection and end-to-end anastomosis, prosthetic patch arthroplasty, and interposi-tion grafting.

HYPOPLASTIC LEFT HEART SYNDROMEIncidence

Hypoplastic left heart syndrome (HLHS) is rare, accounting only for 2% to 3% of allCHDs.43

Anatomy/Physiology

HLHS is a congenital defect in which the left ventricle, as well as the aortic arch, areunderdeveloped or atretic, and atresia of the aortic and mitral valves, or severe

Fig. 8. Coarctationof theaorta.Cardiomegalyandpulmonaryvascular congestion (patienthadpreductal coarctation in segment between innominate artery and left carotid and large VSD).

Fig. 9. Coarctation of aorta: Postoperative day 1. Same patient as in Fig. 8: Appreciate thedifference in heart size.

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stenosis, do not allow cardiac output from the left heart, resulting in minimal LVoutflow.44 The right ventricle, via right-to-left flow through the ductus, supports sys-temic circulation and so is a duct-dependent circulation. Similarly, pulmonary venousreturn can reach systemic circulation only by traversing the atrial septum (via a patentforamen ovale) to reach the right side of the heart.

Clinical Presentation

These patients typically present in the neonatal period listless, cyanotic, and tachyp-neic. As the duct closes, this leads to circulatory shock and metabolic acidosis.Increased pulmonary blood flow leads to an increase in left atrial pressure and subse-quent pulmonary edema. There is a single heart sound, with a systolic ejection murmurand diminished pulses. The ECG shows right atrial enlargement, RVH, and peaked Pwaves. The chest radiograph shows cardiomegaly.45

Management

The main aim of initial management is to stabilize the infant’s condition so that a diag-nosis can be confirmed and a treatment plan can be made. Intubation and ventilationare usually necessary to remove the work of breathing and allow for hemodynamicstabilization. Positive-pressure ventilation alleviates pulmonary edema, and permis-sive hypercapnia can be used to allow the pulmonary vascular resistance to increaseand to reduce pulmonary overcirculation. Ductal patency should be secured withPGE1 infusion. Congestive cardiac failure is treated with diuretics, but if there is wors-ening tachypnea and acidosis with peripheral constriction, inotropic support (typicallydobutamine 5–10 mg/kg/min) might be needed for the volume-loaded right ventricle.46

These measures stabilize most patients, enabling surgery to be planned over thefollowing days. Patients with restrictive or even intact atrial septum pose amore urgentsituation, depending on the severity of the obstruction and subsequent lung injury. Themost severe cases are not compatible with life, but those who remain profoundlycyanotic despite ventilatory support need urgent decompression of the left atriumwith either balloon atrial septostomy in the catheter laboratory or early surgery. Pa-tients need surgical intervention with initial palliative procedure such as a Norwoodoperation followed by a bidirectional Glenn procedure and Fontan procedure. TheNorwood operation, performed in the neonatal period, is a palliative procedure in

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HLHS. The hypoplastic aorta is reconstructed using an aortic or pulmonary artery allo-graft, the main pulmonary artery is divided, a Gore-Tex shunt is placed on the right toestablish pulmonary blood flow, and the atrial septum is excised to provide interatrialmixing. The bidirectional Glenn operation that anastomoses the superior vena cava tothe right pulmonary artery is usually performed at 6 months of age. During the Fontanoperation, systemic venous return is redirected to the pulmonary artery and is usuallyperformed by 1.5 years of age.47,48 After a series of operations, the right ventricle func-tions as the systemic ventricle pumping into a reconstructed aortic arch, and pulmo-nary blood flow is achieved passively through a Fontan-type circulation.

AORTIC STENOSISIncidence

Aortic stenosis is seen in 6% of CHD, with a 5:1 ratio in males.49

Anatomy/Physiology

The aortic stenosis can be at the valvular, supravalvular, or subvalvular level, with thedegree of obstruction determining the severity of disease in the patient. A congenitalbicuspid aortic valve occurs in 1.3% of the population and therefore is one of the mostcommon congenital heart malformations.43 The physiologic impact of aortic stenosisis obstruction of LV outflow, resulting in increased LV afterload.

Clinical Presentation

Approximately 10% to 15% of patients have severe obstruction presenting with CHFin infancy. The physical examination is remarkable for a systolic thrill in the region ofthe upper right sternal border, suprasternal notch, or carotid arteries. There can bean ejection click. The murmur is a rough or harsh systolic murmur grade 2 to 4/6 atthe right intercostal space or left intercostal space, with transmission to the neck. Incases of severe aortic stenosis, the ECG shows LVH. If there is resultant CHF, thechest radiograph shows cardiomegaly.45

Management

Balloon valvuloplasty has generally supplanted open surgical valvotomy as initialtreatment of congenital aortic valve stenosis in children and adolescents.50 Subse-quent progression of stenosis or valve regurgitation is expected, with valve replace-ment considered to be the definitive treatment.

ARRHYTHMIAS

Arrhythmias can be a result of various and often combined abnormalities, such as im-pulse formation, abnormalities in impulse propagation, and abnormalities in auto-nomic influence. Cardiac arrhythmias in children are often caused by an underlyingcongenital heart defect, especially after heart surgery. Certain types of CHD, TOF, cor-rected d-TGA, TAPVR, large ASDs, VSDs, endocardial cushion defects, aortic andsubaortic stenosis, and congenital mitral stenosis are associated with a higher inci-dence of postsurgical rhythm disturbances. The most common postoperative arrhyth-mias include supraventricular tachycardia, ventricular tachycardia, sick sinussyndrome, and complete heart block.51 Other causes of arrhythmias in childreninclude congenital complete heart block, Wolff-Parkinson-White (WPW) syndrome,and long Q-T syndrome. Acquired heart diseases with associated arrhythmias includeviral myocarditis, KD, cardiomyopathies, rheumatic carditis, and cardiac tumors.Arrhythmias also may be associated with myriad systemic disorders, including

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electrolyte derangements, neuromuscular disorders, endocrine disorders, inheriteddisorders of metabolism, and central nervous system diseases. When children presentwith new-onset arrhythmias, the possibility of drug and toxic substance ingestion alsomust be considered.

SUPRAVENTRICULAR TACHYCARDIAIncidence

Paroxysmal supraventricular tachycardia, previously called paroxysmal atrial tachy-cardia, is the most common pediatric arrhythmia and occurs in 1 in 250 to 1 in 1000children.52

Anatomy/Physiology

Electrophysiologic studies have shown that supraventricular tachycardia is several ar-rhythmias. In addition to being caused by abnormal impulse formation, supraventric-ular tachycardia may also be caused by reentry within the sinoatrial node, atrium, AVnodal approaches, and accessory pathways, including WPW syndrome. Most pa-tients with SVT have normal hearts, with 23% having CHD and 22% with WPW syn-drome.53 WPW is associated with CHD, such as TGA. WPW is a preexcitationsyndrome, with an accessory pathway between the atria and ventricles.

Clinical Presentation

Arrhythmias may manifest in several ways, including symptoms of CHF, decreasedcerebral perfusion (eg, syncope, dizziness, irritability, inappropriate behavior),decreased coronary perfusion (eg, anginal chest pain), or perception of the arrhythmia(ie, palpitations). Infants may present with a history of irritability, lethargy, or dyspnea,with decreased appetite and vomiting. In more severe cases, mottling and cyanosismay be present, with varying degrees of CHF. Infants with CHF have enlarged livers,but peripheral edema is rare. Older children may report a history of syncope, dizziness,restlessness, fatigue, and dyspnea, or sudden onset of chest pain or palpitations. Atypical ECG seen in a pediatric patient with supraventricular tachycardia shows a rapidrate and a narrow QRS complex. P waves can usually be seen, but may be obscuredby the ST segment. If P waves are absent, a narrow and regular QRS complex is morelikely to be of supraventricular rather than of ventricular origin. Supraventricular tachy-cardia is characterized by a regular heart rate, which does not fluctuate with agitation,in contrast to sinus tachycardia. The rate of tachycardia in infants ranges from 220 to320 beats per minute, whereas the rate in older children typically ranges from 150 to250 beats per minute.

Management

In stable patients, vagal maneuvers (eg, carotid massage, Valsalva maneuver, gag re-flex, abdominal compression, rectal stimulation in infants) and pharmacologic cardio-version are indicated as the first line of treatment. However, in hemodynamicallyunstable patients, synchronized cardioversion should be promptly used. The historyand clinical findings should be assessed quickly to determine the most appropriatecourse of action. Adenosine has become the first-line pharmacologic therapy for sup-raventricular tachycardia in pediatric patients who present to the emergency depart-ment.54 It has a rapid onset of action, usually within 10 seconds, and a half-life of onlyseveral seconds. Because of its short half-life, it is ineffective if administered tooslowly. In young patients, adenosine initially should be administered as a rapid IVbolus dose of 0.1 mg/kg, with subsequent dose of 0.2 mg/kg. Patients weighingmore than 50 kg may be given an initial dose of 6 mg, with a subsequent dose of

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12 mg given 1 to 2 minutes later, if required. If IV access is delayed or if adenosine isnot readily available or is unsuccessful in cardioverting a hemodynamically unstablepatient, immediate synchronized cardioversion with 0.5 to 1 J/kg should be instituted.If the initial attempt is unsuccessful, the current should be doubled successively untileffective or until a dose of 10 J/kg is reached.55 Because cardioversion may not besuccessful in the presence of hypoxia or acid-base imbalance, airway support andventilation may be required to help correct an underlying acidosis. Once the patient’srhythm is converted to sinus rhythm, a pediatric cardiologist should be consulted forfurther management and evaluation.

COMPLETE HEART BLOCKIncidence

Complete AV heart block may be congenital or acquired. Congenital complete AVheart block is seen in 1 in 22,000 live births.

Anatomy/Physiology

Congenital heart block may be associated with structural heart defects or withmaternal collagen vascular disease. It is speculated that maternal immunoglobinscross the placenta and damage the fetal cardiac conduction system.56 Acquired com-plete AV heart block may be secondary to nonsurgical causes, such as inflammatoryor infectious diseases,57 or iatrogenic after cardiac surgery (especially after VSDrepair). Postsurgical complete AV heart block may be transient or permanent.58

Improved knowledge of the location of the conduction system has helped decreasethe incidence of postsurgical heart block to less than 1%.

Clinical Presentation

The usual presentation in infancy is CHF. Older children with congenital complete AVheart block tend to present with syncope, diminished exercise tolerance, and fatigue.Congenital heart block presents with bradycardia. The ventricular rate is usually lessthan 75 beats per minute and rarely more than 100 beats per minute while at rest.Third-degree or complete heart blocks have independent atrial and ventricular activity.There are regular P waves at a normal heart rate for age. The QRS complexes are alsoregular, but at a slower rate than the P waves. Patients may be evaluated with 24-hourHolter monitoring and echocardiography to assess the possibility of an associatedcongenital heart lesion or inadequate surgical palliation.

Management

If the patient is symptomatic, isoproterenol, epinephrine, external pacer, or temporarytransvenous ventricular pacing are sometimes required. The emergency treatment ofcongenital or acquired nonsurgical heart block is similar. Priorities are adequateoxygenation and ventilation. Pharmacologic therapy may be tried if treatment ofacidosis does not help perfusion. An infusion of isoproterenol (0.02–0.5 mg/kg/min)or epinephrine (0.05–0.5 mg/kg/min) should be started to increase the junctional orventricular escape rate. Adequate intravascular volume should be maintained duringepinephrine infusion, because its vasodilatory effect may result in lowered BP. If car-diac output is inadequate despite pharmacologic measures, an external pacer shouldbe applied while awaiting temporary ventricular pacing.59

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OTHER HEART BLOCK

AV block is found when there is an interruption of the conduction of the normal sinusimpulse and the subsequent ventricular response. In addition to third-degree blocks(complete heart block), there are first-degree and second-degree blocks.The first-degree block has a prolonged PR interval because of delayed conduction

through the AV node. This block is the result of a cardiomyopathy, CHD, postcardiacsurgery, or digitalis toxicity or can be found in healthy patients.In a second-degree block, not all of the P waves are followed by QRS complexes.

The Mobitz type I Wenckebach phenomenon has a PR interval that gets progressivelylonger until the QRS complex is completely decreased. The block is at the AV nodelevel and can be attributed to myocarditis, cardiomyopathy, surgery, CHD, or digitalistoxicity. The Mobitz type II block has similar causes, but the block is at the bundle ofHis. AV conduction is either all or none. There is potential for a complete block todevelop. In 2-to-1 or 3-to-1 blocks, the block is at the level of the AV node, but canalso be at the bundle of His. Mobitz II block is rare in children.

Management

First-degree AV block is awell-tolerated condition. Management is aimed at identifyingany reversible underlying cause and following the patient closely to be sure that thecondition does not progress. Mobitz I block is well tolerated as well and does not al-ways require therapy. For acute symptoms, treatment with IV atropine or isoproterenolusually provides temporary improvement in conduction, but a pacemaker is the safestlong-term therapy in symptomatic patients if the underlying cause is not reversible.Mobitz II may have abrupt progression to complete block. When it occurs as the resultof surgical trauma, implantation of a pacemaker has been advised.60

ACQUIRED DISEASE

Inflammatory diseases of the heart are grouped under carditis. Included in this groupare myocarditis, pericarditis, and endocarditis (along with valvulitis).

Myocarditis

Clinical presentationThere are several different causes of myocarditis. Infectious-mediated andautoimmune-mediated, as well as toxin-mediated, processes can contribute to the in-flammatory response in the myocardium.61 Most cases of myocarditis in the UnitedStates and Western Europe result from viral infections such as coxsackievirus, influ-enza, cytomegalovirus, herpes simplex virus, hepatitis C, rubella, varicella, mumps,Epstein-Barr virus, human immunodeficiency virus, and respiratory syncytial virus.Nonviral causes such as protozoans (Chagas disease seen in South America) alsocause myocarditis. Less frequently, bacteria, rickettsia, fungal, mycobacteria, andother parasites can be causes; drugs (including antimicrobial medications), hypersen-sitivity, autoimmune, or collagen vascular diseases such as systemic lupus erythema-tosus, mixed connective tissue disease, rheumatic fever, rheumatoid arthritis, andscleroderma; or other disorders such as KD and sarcoidosis. In most cases, however,idiopathic myocarditis is encountered.62 Infants may present with vomiting, decreasedactivity, poor feeding, and CHF, with tachycardia, tachypnea, a gallop rhythm, anddecreased heart tones. There are no specific laboratory tests for myocarditis. Erythro-cyte sedimentation rate, white blood cell count, myocardial enzymes, and cardiactroponin are normal or increased. Troponin levels are believed to be more sensitivethan cardiac enzymes.63 ECG abnormalities are common but are nonspecific. There

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is tachycardia, low QRS voltages, flattened or inverted T waves with ST-T wavechanges, and prolongation of the QT interval (Fig. 10). Arrhythmias such as prematurecontractions are also seen. Chest radiography shows cardiomegaly and pulmonaryvenous congestion, depending on the extent of the disease (Fig. 11). Echocardiogramstudies show dilatation of the heart chambers and decreased LV function. The echo-cardiogram also helps to evaluate myocardial contractility and the presence of a peri-cardial effusion (Fig. 12). Radionuclide scanning and endomyocardial biopsies canhelp in confirming the disease. Mortality in symptomatic neonates with acute viralmyocarditis can be significant.64

ManagementManagement of myocarditis revolves around identifying a cause and, if identified,treating that suspected agent, treating the CHF, and controlling the arrhythmias. Sup-plemental oxygen, diuretics like furosemide, and inotropic agents such as dopamineand dobutamine are mainstays in treatment, along with the use of angiotensin-converting enzyme inhibitors like captopril. Digoxin is used cautiously because of itspotential to induce arrhythmias. In KD, high-dose immunoglobulin has been beneficial.Other treatment modalities, such as immunosuppressive agents and corticosteroids(except in severe rheumatic carditis), are not universally accepted. Acute fulminantmyocarditis resulting in rapid hemodynamic deterioration is 1 indication for mechan-ical support by using rapid-response extracorporeal membrane oxygenation.65

Pericarditis

Clinical presentationInflammation of the pericardium is the hallmark of pericarditis. The most commoncause in infancy is a viral cause such as coxsackie, echovirus, adenovirus, or influ-enza. Viral pericarditis is usually associated with a viral myocarditis, with the myocar-ditis being the more prominent entity. Acute pericarditis may occur secondary toinfectious agents such as Staphylococcus aureus, Streptococcus pneumoniae, Hae-mophilus influenzae, Neisseria meningitides, and streptococci as well as tuberculosis;collagen vascular disease; cardiac surgery; drug therapy; as a manifestation of

Fig. 10. Myocarditis. 7-year-old patient, tachycardia: heart rate, 143 beats/min; P-R, 57 ms;QRS 62 ms; QT/QTc, 282/435 ms. (Courtesy of Robert Bramante, MD and AnnabellaSalvador, MD, Manhasset, NY.)

Fig. 11. Myocarditis. Cardiomegaly (same patient as ECG in Fig. 10). (Courtesy of RobertBramante, MD and Annabella Salvador, MD, Manhasset, NY.)

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rheumatic fever; or in association with chronic renal failure and dialysis. Postpericar-diotomy syndrome is seen in patients who have had cardiac surgery involving interrup-tion of the pericardium.66 The predominant symptom of acute pericarditis is precordialchest pain in as many as 80% of children, exacerbated by breathing, coughing, or mo-tion. Patients are most comfortable in the upright position. In the absence of cardiactamponade or pneumonitis, respiratory distress is not a common clinical feature. Fe-ver, present in most cases of acute pericarditis, cannot reliably differentiate pericar-ditis caused by infectious agents, collagen vascular disease, or rheumatic fever.There is usually a predisposing illness in the history, with an upper respiratory infection

Fig. 12. Myocarditis. Point-of-care ultrasonography: parasternal long view, moderate-sizedeffusion, no collapse or tamponade; however, the heart showed decreased contractility(same patient as ECG in Fig. 10 and chest radiograph in Fig. 11). (Courtesy of RobertBramante, MD and Annabella Salvador, MD, Manhasset, NY.)

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or, in the case of a bacterial pericarditis, a pneumonia, empyema, osteomyelitis, py-elonephritis, or tonsillitis. A pericardial friction rub is diagnostic.67 A murmur maynot be found and the heart is hypodynamic.On ECG, there is a low-voltage QRS complex. Early in the disease, ST segments are

increased everywhere, except in V1 and aVR. Later in the disease, ST segments returnto normal and the T waves flatten or invert.68 A chest radiograph shows cardiomegaly,with the heart in a water-bottle shape. Echocardiogram is the key to establishing thepresence of an effusion. In addition, the echo can also evaluate for cardiac tampo-nade, because it shows the collapse of the right atrial wall or the right ventricularwall in diastole.66

ManagementIn milder cases, nonsteroidal antiinflammatory drugs can be used to treat thediscomfort. In more severe cases, especially if an infectious cause is suspected,pericardiocentesis is needed in addition to antibiotics, antivirals, or antifungals,depending on the suspected cause. Multiple blood cultures are also indicated, aswell as standard fluid studies. In postpericardiotomy syndrome, which can affectas many as 30% of pediatric patients who undergo cardiovascular surgery involvingthe pericardium, the patients present with fever, irritability, and a pericardial frictionrub from a month to a few months postoperatively.66

Endocarditis

IncidenceInfective endocarditis is an uncommon but life-threatening infection. CHD is a signif-icant risk factor in infective endocarditis. In infancy, endocarditis is rare and is asso-ciated with open heart surgery.69

Anatomy/physiologyIt is believed that turbulent flow from pressure gradients leads to endothelial damageand thrombus formation. Transient bacteremia then seeds the damaged areas. Withthe exception of a secundum ASD, all CHDs and valvular heart diseases are proneto endocarditis, especially if there is any artificial material within the heart (prostheticheart valve or graft). Common bacterial causes include Streptococcus viridans,enterococci, and Staphylococcus aureus as well as fungal and bacteria such asEikenella and Cardiobacterium.69

Clinical presentationThe usual presentation is with fulminant disease and a septic appearance. A heartmurmur and fever are always present. Adult patients tend to have more embolic phe-nomena. Using the Duke Criteria for Infective Endocarditis, a patient must have 2 ma-jor criteria or 1 major criterion with 3 minor criteria or 5 minor criteria. Major criteriainclude 2 separately obtained positive blood cultures growing the typical microorgan-isms and an echocardiogram with endocardial involvement such as an intracardiacmass on a valve, abscess, partial dehiscence of a prosthetic valve, or new valvularregurgitation. Minor criteria include predisposing conditions, fever, vascular phenom-ena (emboli, hemorrhages, Janeway lesions), and immunologic phenomena (glomer-ulonephritis, Osler nodes, Roth spots, rheumatoid factor), microbiological evidence(positive blood culture not meeting major criteria), and echocardiographic findings(not meeting major criteria).70 Although an echocardiogram identifying valvular vege-tation is helpful in the evaluation, the echocardiogram is not 100% sensitive or spe-cific. Because of this, a negative echocardiogram does not exclude endocarditis.Obtaining a positive blood culture makes a definitive diagnosis.

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ManagementThree or more blood cultures should be taken irrespective of body temperatureapproximately 1 hour apart. The isolation of a specific microorganism is critical fordetermining antibiotic therapy. In cases complicated by sepsis, severe valvulardysfunction, conduction disturbances, or embolic events, empirical antimicrobial ther-apy should be started after blood cultures are obtained. Empirical antibiotic therapywith vancomycin and gentamicin should be initiated in the emergency department.71

Treatment regimens may take place for weeks to be certain that the microorganismhas been eliminated. Prophylactic antibiotics are recommended before dental proce-dures for patients with prosthetic cardiac valve and previous history of infectiousendocarditis. In addition, it is also recommended for patients with CHD with unre-paired cyanotic CHD, including palliative shunts and conduits, or completely repairedcongenital heart defect with prosthetic material or device, whether placed by surgeryor by catheter intervention, during the first 6 months after the procedure, or repairedCHD with residual defects at the site or adjacent to the site of a prosthetic patch orprosthetic device (which inhibit endothelialization). Another group of patients whoneed prophylaxis are those who received cardiac transplantation and have developedcardiac valvulopathy.72

KDIncidence

With an annual incidence in the United States of 4 to 15 cases per 100,000 childrenyounger than 5 years, a male/female ratio of 1.5:1, and seasonal peaks in winterand spring, KD has become the leading cause of acquired heart disease in childrenin the developed world.73

Anatomy/Physiology

KD is a self-limiting generalized systemic vasculitis of indeterminate cause. Biochem-ical and immunologic evidence suggests endothelial cell activation and injury. Studiesof KD pathogenesis show a progression of arterial lesions accompanying KD vasculitisand several immunoregulatory changes, including a deficiency of circulating CD81suppressor/cytotoxic T cells; an abundance of circulating B cells spontaneously pro-ducing immunoglobulins; and circulating, activated monocytes.73 Stage I (0–9 days) ischaracterized by perivasculitis of small arteries. Pericarditis, myocarditis, inflamma-tion of the AV conduction system, and endocarditis with valvulitis are also present.Stage II (12–25 days) is characterized by panvasculitis of medium-sized, muscular ar-teries with aneurysm formation and thrombosis. Myocarditis, pericarditis, and endo-carditis with valvulitis may also be present. During stage III (28–31 days), myointimalproliferation in the coronary and other medium-sized arteries is prominent, and acuteinflammation disappears from the microvasculature. In stage IV (after 40 days), scar-ring of arteries with stenosis may occur.74,75

Clinical Presentation

KD primarily affects infants and younger children and can occur in endemic orcommunity-wide epidemic forms. The hallmarks of the disease are fever of at leastgreater than or equal to 5 days duration, and presence of 4 of these features: bilateralnonexudative conjunctivitis, erythema of the mucous membranes (lips, oral mucosa),rash, cervical adenopathy, and extremity changes. Bilateral conjunctival injectioninvolving the bulbar conjunctivae is seen around the time of the fever. There can beerythema; peeling, cracking, or bleeding from the lips andmouth; a strawberry tongue;and diffuse erythema of the mucosa of the oropharynx. The extremity changes include

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erythema to the palms and soles, with induration and desquamation to the fingers andtoes. Sometimes, early desquamation in the perianal region can occur. There can bean extensive erythematous rash, which is usually a nonspecific diffuse maculopapularrash. The cervical lymphadenopathy is generally unilateral, and usually 1 node isgreater than 1.5 cm in diameter.76,77 Although most cases fulfill the principal diag-nostic criteria, about 15% of cases have incomplete clinical presentations, with coro-nary artery complications.78 Therefore, any infant younger than 6 months with feverduration of 7 days or more, increase of C-reactive protein (CRP) and erythrocyte sedi-mentation rate (ESR), and no other explanation for the febrile illness should have anechocardiogram. In any child with unexplained fever lasting more than 5 to 7 dayswith some of these laboratory findings, incomplete KD should be considered andechocardiography should be obtained as well. Furthermore, KD can be diagnosedwhen 4 or more principal criteria are present on day 4 of illness.77 Coronary artery an-eurysms or ectasia have been found in 15% to 25% of untreated children with KD.79

Coronary artery aneurysms more than 8 mm in diameter (so-called giant aneurysms)can lead to acute myocardial infarction, which may result in hypotension, arrhythmia,or sudden death.80 In the acute phase of KD, there can be involvement of all parts ofthe heart: the pericardium, the myocardium, the endocardium, the valves, and the cor-onary arteries. The cardiac examination can show tachycardia, a gallop, and a flowmurmur or regurgitant pansystolic murmur. Depressed myocardial function can pre-sent as cardiogenic shock. The ECG shows nonspecific ST and T wave changes, aprolonged PR interval, or arrhythmia. Laboratory findings include leukocytosis, ane-mia, and thombocytosis (appears in second week, peaking in third week). Thrombo-cytopenia in active disease is a risk factor for coronary aneurysms. There isincrease of CRP levels or ESR. Serum transaminases can be moderately increased.g-glutamyl transpeptidase level is increased in most patients. Albumin synthesis de-clines in the acute phase, and hypoalbuminemia is common. Urinalysis shows so-called sterile pyuria, with white cells (often in the range of 10 to 50/high-power field)noted on microscopic evaluation but not by dipstick.77

Management

Any patient suspected of having KD needs to be admitted. The goal of initial manage-ment is to reduce inflammation and thus reduce the risk of coronary artery abnormal-ities. Pharmacologic management of the acute phase of KD includes aspirin and IVimmunoglobulin (IVIG). High-dose aspirin at 80 to 100 mg/kg per day is dosed 4 timesa day. Length of treatment with aspirin is variable.81 IVIG is believed to have a gener-alized antiinflammatory effect and is dosed at 2 g/kg in a single infusion, administeredslowly, over 8 to 12 hours, to minimize the chance of hypersensitivity or hyperpyrexiareaction and to prevent solute overloading. Best results are seen when IVIG is startedwithin the first 7 to 10 days of illness.82,83

CARDIOMYOPATHIES

Cardiomyopathies affect the heart muscle and are divided into 4 categories by theWorld Health Organization: hypertrophic, dilated, restrictive, and arrhythmogenicright ventricular cardiomyopathy.84 However, as a result of new developments in mo-lecular genetics in cardiology and the emergence of ion channelopathies as diseasespredisposing to potentially lethal ventricular tachyarrhythmias, a new classificationhas been proposed by a panel of experts under the auspices of the American HeartAssociation. This panel recommends that cardiomyopathies be classified as primary([a] genetic, [b] mixed [genetic and nongenetic], or [c] acquired), and secondary.

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Cardiomyopathies are defined as a heterogeneous group of diseases associated withfailure of myocardial performance, which may be mechanical (eg, diastolic or systolicdysfunction) or a primary electrical disease prone to life-threatening arrhythmias,associated with ventricular hypertrophy or dilatation from a variety of causes, whichare frequently genetic. Cardiomyopathies can be either confined to the heart or bepart of a generalized systemic disorder.85

Hypertrophic cardiomyopathy (HCM) would be in the primary genetic category, clin-ically heterogeneous but a common autosomal-dominant genetic heart disease86

(1:500 of the general population for the disease phenotype recognized by echocardi-ography), which is probably the most frequently occurring cardiomyopathy. HCM, inthe United States, is the most common cause of sudden cardiac death in the young,including trained athletes,87 and is an important substrate for heart failure disability atany age. There is significant ventricular muscular hypertrophy and increased ventric-ular contractility, but these factors limit or reduce ventricular filling. The left ventricle isstiff and affects diastolic ventricular filling. The physical examination is notable for asharp upstroke of the arterial pulse.88 There can be a systolic ejection murmur or hol-osystolic murmur. The ECG shows LVH, ST, and T wave changes, deep Q waves,and decreased R waves. The chest radiograph may show a globular heart orcardiomegaly.Dilated cardiomyopathies (DCM), a mixed form of cardiomyopathy, are a common

and largely irreversible form of heart muscle disease, with an estimated prevalence of1:2500; it is the third most common cause of heart failure and the most frequent causeof heart transplantation. It results from infectious or toxic causes. DCM may manifestclinically at a wide range of ages (most commonly in the third or fourth decade but alsoin young children) and usually is identified when associated with severe limiting symp-toms and disability. DCM has ventricular dilatation with systolic dysfunction. DCMleads to progressive heart failure and a decline in LV contractile function, ventricularand supraventricular arrhythmias, conduction system abnormalities, thromboembo-lism, and sudden or heart failure–related death.89 A significant S3 is found onexamination.Restrictive cardiomyopathies (RCM) limit diastolic filling of the ventricles. This is the

least common form and results from noncompliant ventricular walls. RCM has multiplecauses and may result from myocardial diseases, including noninfiltrative or infiltrativeprocesses, storage diseases, endomyocardial diseases, myocarditis, and after car-diac transplantation.Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an uncom-

mon form of inheritable heart muscle disease (estimated at 1:5000). Even although it isfrequently associated with myocarditis (enterovirus or adenovirus in some cases),ARVC/D is not considered an inflammatory cardiomyopathy, but rather a primary ge-netic cardiomyopathy. ARVC/D involves predominantly the right ventricle with pro-gressive loss of myocytes and fatty or fibrofatty tissue replacement, resulting inregional (segmental) or global abnormalities. In addition, evidence of LV involvementwith fibrofatty replacement, chamber enlargement, and myocarditis is reported inup to 75% of patients. It should be considered in individuals with exercise-induced ar-rhythmias or syncope, 1 or multiple left bundle branch QRS morphology tachycardias,or unexplained right ventricular enlargement on the echocardiogram.90 ECG showsabnormal repolarization with T wave inversion in leads V1 to V3 and small-amplitudepotentials at the end of the QRS complex (ε wave); Brugada syndrome–like RBBBand right precordial ST segment increase accompanied by polymorphic ventriculartachycardia have also been reported in a small subpopulation of patients withARVC/D.90

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SUMMARY

The diagnosis and management of pediatric cardiac emergencies can be challengingand complicated. Early presentations are usually the result of ductal-dependent le-sions and appear with cyanosis and shock. Later presentations are the result of vol-ume overload or pump failure and present with signs of CHF. Acquired diseasesalso present as CHF or arrhythmias.

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