01 Cardiovascular I

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Cardiovascular System

Cardiovascular System I 1

Cardiovascular System I

Objectives

Present the clinical features and emergency management of cardiovasculardisorders, including:

Recognize congenital and acquired heart disease. Outline management of ductal dependent lesions. Identify patients with myocarditis.

Case Study 1: Rapid Breathing

A 10-day-old infant is brought to the ED by his mother for rapid breathing and not eatingwell. The child was a product of normal spontaneous vaginal delivery, and spent twodays with mother in the hospital. He had an uneventful course, including circumcision.

Birth weight was 3.2 kg.

Instructor Information

Begin discussion of assessment and management of a patient with compensated shockand cardiopulmonary failure.

The child was slow to breastfeed since birth. He would gasp and cry after sucking for a

short time. Difficulty feeding. He had 3 to 4 wet diapers per day. There was nocongestion or fever. He had no vomiting with feedings. He had two yellow seedy stools

since passing meconium after birth.

The PAT is as follows: Appearance: Abnormal. Fussy, pale with central cyanosis, sweaty. Breathing: Abnormal. Weak cry, tachypnic, rales, grunting, nasal flaring. Circulation: Abnormal. Tachyardic, gallop rhythm, weak pulses.

The child is ill-appearing, in respiratory distress, fussy, and has a weak cry. Additionally,

there is nasal flaring and occasional grunting. The child is pale, cyanotic centrally and in

all extremities, and sweaty to touch.

The patients vital signs are as follows:

Heart rate: 170 bpm Respiratory rate: 70 breaths/min Blood pressure: 82/40 mm Hg Temperature: 37C (rectal)


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Weight: 3.4 kg Oxygen saturation: 90% on room air

Initial assessment:

A: No evidence of obstruction. B: Elevated respiratory rate and labored. C: Pale, diaphoretic, tachycardia, weak pulse, cyanosis. D: Glasgow Coma Scale (GCS) grossly normal but in distress and inconsolable. E: No signs of head injury, fractures, or bruising.

Lung sounds equal bilaterally with rales in both bases.Hyperactive precordium with a gallop rhythm.

Pulses weak in distal and lower extremities.

Distended abdomen with liver palpable 4 cm below right costal margin.

Key Questions

What is your general impression of this patient?

Core Knowledge PointsGeneral Impression

Categorize this patient into one of the following categories:

Stable Respiratory Distress

Respiratory Failure Shock Primary CNS Dysfunction Cardiopulmonary Failure/Arrest

The infant is in impending cardiopulmonary failure (compensated shock): Appearance,

work of breathing, and circulation are abnormal, indicating cardiopulmonary failure.

Key Questions

What are your initial management priorities?

Critical Actions

ABCs.Give 15L oxygen by nonrebreather mask or 100% oxygen by bag-mask ventilation

(BMV), or perform endotracheal intubation.Start an IV and obtain blood glucose.


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Perform an ECG and monitor rhythm on cardiac monitor.Get a chest radiograph.

Administer fluid challenge: 10 cc/kg NS to support circulation in shock.

Administer prostaglandin E1 (PGE1) at 0.05 to 0.1 mcg/kg/min.

Intubate to protect against apnea and relieve stress from work of breathing.Consider furosemide (0.5 to 1 mg/kg) if patient has not responded to initial therapy.

Do a sepsis work-up and then give antibiotics.Defer lumbar puncture if the infant continues to be in respiratory distress and is unstable

from cardiovascular compromise.

Consult Cardiology or transfer to pediatric cardiology center emergently.Perform an echocardiogram.

If blood pressure and perfusion do not improve, add an inotropic agent, such as:

Dobutamine: 2 to 20 mcg/kg/min Epinephrine: 0.1 to 1.5 mcg/kg/min

Case Development

This infant is in congestive heart failure (CHF):

Poor feeding and easy fatigability Gallop rhythm and enlarged liver Diminished pulses

The infant is in shock, showing altered mental status and compensated shock

(tachycardia, diaphoresis, respiratory distress, and normal blood pressure in upperextremities).

The infant has a possible ductal dependent lesion:

Right age for presentation of shock triggered by closure of the ductus arteriosus Measure blood pressure in four extremities. Assess oxygenation response to supplemental oxygen.

There are several possible etiologies of this infants condition.

Version 1:A blood pressure differential is noted in the lower extremities.

Oxygenation improves to 99% with supplemental oxygen.A chest radiograph shows cardiomegaly and pulmonary edema.

An echocardiogram demonstrates coarctation of the aorta.The infant improves with PGE1 infusion, diuretics, and inotropes.


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Version 2:

Oxygenation fails to improve with supplemental oxygen (remains 90%).Oxygenation declines further to


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Left axis: Hypoplastic right heart, tricuspid atresia, endocardial cushion defect(AV canal)

ST-T changes, strain, ischemia Dysrhythmia Prolonged QT Low voltage

Laboratory studies should include:

Glucose: Any child in distress needs to have hypoglycemia excluded CBC: Look for anemia, signs of sepsis Electrolytes: Congenital adrenal hyperplasia, salt-wasting form Arterial blood gas: Hyperoxia test

Core Knowledge PointsFetal Circulation

In the normal fetal circulation, oxygenated blood returns from the placenta via the ductus

venosus, mixing with some systemic venous return blood in the inferior vena cava.

Oxygenated blood preferentially shunts across the foramen ovale (FO) to the left atrium(LA).

The left ventricle ejects the most oxygenated blood to the carotids and coronaries.

Superior vena cava (SVC) returns deoxygenated blood to RA where it mixes withoxygenated blood from the placenta.

Preferentially enters RV.

RV ejects into PA. No pulmonary capillary flow, so PA is shunted into the descending aorta via the

ductus arteriosus.

The right ventricle (RV) pumps less oxygenated blood into the pulmonary artery (PA).

The pulmonary vascular bed is vasoconstricted, so most of the blood is shunted through

the ductus arterious to mix with the systemic arterial circulation in the descending aorta(distal to the coronary and carotid arteries), thus delivering less oxygenated blood to the

rest of the systemic arterial circulation.

Core Knowledge PointsTransposition of the Great Arteries

Transposition of the great arteries (TGA) is also known as transposition of the greatvessels (TGV). The right ventricle pumps deoxygenated blood into the aorta, while the

left ventricle pumps oxygenated blood into the pulmonary artery.


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A shunt between the left and right circulations is required to maintain sufficientoxygenation. In the diagram, a ventricular septal defect (VSD) permits mixing between

the left and right ventricles to permit some oxygenated blood from the lungs to reach thesystemic circulation.

Without a VSD, the ductus arteriosus must remain patent to maintain sufficient

oxygenation. Once the ductus closes, oxygenation will markedly decline. Ductus patencycan be maintained with a prostaglandin E1 infusion.

Differential diagnoses include:

Other cyanotic and acyanotic congenital structural heart disease Ductal dependent coarctation Hypothermia Sepsis TORCH Group of infections that can lead to birth defects including congenital

heart disease. Includes toxoplasmosis, rubella, cytomegalovirus (CMV) andherpes simplex.

CAH (congenital adrenal hyperplasia) Hypoglycemia Shaken baby syndrome/intracranial lesion Catastrophic gastrointestinal process, e.g., volvulus

Core Knowledge PointsNormal CV System Function

Normal cardiovascular system (CVS) function in pediatric patients is represented bynormal vital signs and oxygen saturation, as well as the overall appearance of the child. A

normal cardiac output is required to meet the bodys needs; it is defined as the amount ofblood that the heart pumps each minute and is calculated using a combination of heart

rate and ventricular stroke volume.

Many physiological parameters such as the heart rate, stroke volume, mean arterial bloodpressure, and vascular resistance affect the cardiac output. Stroke volume is the quantity

of blood ejected from the heart with each contraction and is a function of the pumpingaction of the ventricle, which is dependent on preload, afterload, and contractility of the

ventricle.

Infants and young children rely mainly on the heart rate to increase cardiac output, asthey have limited capacity to change stroke volume. Children older than 8 to 10 years of

age develop the capacity of adults to change the stroke volume and heart rate to improvecardiac output. Oxygen delivery is the amount of oxygen delivered to the entire body per

minute and is an essential component for adequate cardiac function. If the oxygendelivery falls for any reason, supplemental oxygen is required and/or the cardiac output


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must increase to maintain adequate oxygen delivery to the tissues. Oxygen delivery to thetissues is determined by the amount of blood flow through the lungs, the arterial oxygen

content (dependent on oxygenation and hemoglobin concentration), and the cardiacoutput. Without adequate delivery, the metabolic demand of tissues is not met and shock

(inadequate substrate delivery to meet metabolic demands) begins.

Normal vital signs for various ages are as follows:

HR RR BP (systolic)

Newborn 90-180 40-60 60-901 month 110-180 30-50 70-104

3 months 110-180 30-45 70-1046 months 110-180 25-35 72-110

1 year 80-160 20-30 72-110

2 years 80-140 20-28 74-1104 years 80-120 20-26 78-1126 years 75-115 18-24 82-115

8 years 70-110 18-22 86-118

10 years 70-110 16-20 90-121

12 years 60-110 16-20 90-12614 years 60-110 16-20 92-130

Core Knowledge PointsTransition from Fetal Circulation

The placental circulation is interrupted at birth, which increases the systemic arterial

blood pressure.

The newborn becomes hypoxic with the discontinuation of the placental flow that theyrelied on in utero. This causes an increase in blood pressure, heart rate, and the start of

spontaneous respirations. The respirations help decrease pulmonary vascular resistanceand increase the pulmonary blood flow.

The pulmonary artery pressure decreases and there is an increase in pulmonary venous

return and left atrial pressure, which closes the foramen ovale.

Finally, the increase in systemic arterial pressure and decrease in pulmonary arterypressure cause flow through the ductus arteriosus to reverse.

This initial rapid change slows down over the first 24 hours of life and pulmonary artery

pressures continue to decrease toward adult levels over the next 6 weeks of life. Some ofthis change in pressure is aided by the anatomic structure of pulmonary vessels in the

fetus and newborn, which have a thicker medial smooth muscle layer with increasedvasoreactivity.


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Core Knowledge PointsCyanotic Heart DiseaseCyanotic heart disease (CHD) results from structural and flow anomalies that developed

in utero.

In children with structural congenital heart disease, the changes that occur at birth and theinterruption of intrauterine flow place great stress on the infant's cardiovascular system.

Oxygenation is not possible for the infant who relied on the extraneous shunting (in

utero) that they received from the ductus arteriosus.

The normal oxygen saturation on the right side is from 70% to 75% and on the left side

from 95% to 98%.

The infant shunts deoxygenated blood into the systemic circulation; this is called "right-

to-left shunting." Some cyanotic heart disease conditions are highly dependent onshunting through the ductus arteriosus (e.g., transposition of great arteries [TGA]), in

which case complete closure of the ductus is a terminal event.

Cyanosis may present shortly after birth, when the ductus arteriosus begins to close.

The lesions most commonly seen that are cyanotic in presentation include the five Ts(truncus arteriosus, tetralogy of Fallot, transposition of the great vessels, tricuspid atresia,

and total anomalous pulmonary venous return), severe aortic stenosis, hypoplastic leftheart, and severe coarctation of the aorta.

Core Knowledge PointsTetralogy of Fallot (TOF)

Tetralogy of Fallot (TOF) consists of a VSD, an overriding aorta, right ventricular

hypertrophy, and pulmonic stenosis.

The degree of cyanosis and the severity of the TOF is largely dependent on the degree ofpulmonary blood flow achieved (and hence the severity of the pulmonic stenosis).

Severe pulmonary hypoperfusion results in more severe cyanosis.

Core Knowledge PointsTriscuspid Atresia

Tricuspid atresia is a form of hypoplastic right heart.

The right ventricle distal to the tricuspid valve is hypoplastic.


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Both right and left ventricles pump blood into a common outflow vessel (common trunk).

Right and left mixing occurs.

Core Knowledge PointsTotal Anomalous Pulmonary Venous Return (TAPVR)

The pulmonary veins drain into the right side of the heart.

Right-to-left shunting occurs through an atrial septal defect (ASD), VSD, or patent ductus

arteriosis (PDA).

Core Knowledge PointsCyanosisCyanosis as a presenting sign can be secondary to respiratory, cardiac, and hemoglobindisorders.

Normal newborns will have cyanosis of the hands and feet. This is called acrocyanosis

and is caused by cold stress and peripheral vasoconstriction.

Generalized, or central cyanosis, is more ominous and is exacerbated by crying. Therespiratory rate in children with cyanotic heart disease may not be as elevated as one

would expect to see as with cyanosis caused by respiratory disorders. The baby may alsohave signs of shock with poor distal perfusion, cool extremities, weak cry, and a fast

heart rate.

Core Knowledge PointsHyperoxia Test

To differentiate between the causes of cyanosis, apply 100% oxygen.

In infants with respiratory and hemoglobin disorders, the PaO2 will increase significantly.

The child with a cyanotic heart disease from a significant right to left shunt will have alow PaO2 to start, which will only increase slightly with 100% oxygen because

deoxygenated blood bypasses the lungs and goes directly to the left side of the heart. This

dilutes the fully oxygenated blood coming from the lungs with deoxygenated blood. Theoxygen saturation of the resultant mixture will never reach 100% (hence, PaO2 will never

rise significantly above 100 mm Hg despite 100% inspired oxygen).

This is called the hyperoxia test and may help to distinguish cyanotic heart disease fromrespiratory causes, although severe respiratory illness may also result in low oxygen

saturation despite the application of oxygen.


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Most of these patients present during the first 6 months of life when the shunt orobstruction overwhelms the cardiac compensation and function.

Clinical features include signs of congestive heart failure, such as tachypnea, tachycardia,

diaphoresis, decreased feeding, hepatomegaly, various systolic flow murmurs, and galloprhythms, depending on the specific lesion.

The child may present with decreased activity or poor sleeping with respiratory distress.

Diagnostic studies include chest radiograph, ECG, and echocardiogram.

The chest radiograph will show an abnormal cardiac shadow or increased pulmonary

vascular flow.

The ECG may show an abnormal axis, QRS changes, ST segment changes, and chamberenlargement.

The definitive testing is the two-dimensional echocardiogram that will define the

abnormality and the degree of congestive heart failure.

Critical Actions

Provide supplemental oxygen and assist ventilation as needed.Elevate the head and shoulders about 45 degrees.

Place cardiorespiratory and pulse oximetry monitoringObtain IV access.

Send laboratories (electrolytes, blood urea nitrogen [BUN], creatinine, complete bloodcount).

Obtain chest radiograph and ECG.Administer furosemide, nitroglycerin, and digoxin.

Administer inotropic agent for signs of shock.

Case Study 2: Chest Pain, Shortness of Breath

A 10-year-old boy presents with the chief complaint of chest pain and shortness ofbreath. Previously he had 5 days of cold and cough symptoms. He has been lying around

a lot and has missed 1 week of school. He is usually a very active child but complainsthat he is just too tired to play.


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Instructor InformationBegin discussion of a patient with respiratory distress and cardiogenic shock.

The PAT is as follows:

Appearance: Abnormal. Breathing: Abnormal. Circulation: Abnormal.

Vital signs include: Heart rate: 130 bpm Respiratory rate: 44 breaths/min Blood pressure: 90/65 mm Hg Temperature: 37.8C

Oxygen saturation: 90% on room air, increases to 100% on supplemental oxygen

Initial assessment:

A: Patent B: Intermittently shallow and deep; rapid respiratory rate C: Pale; pulse rapid, thready, and weak D: No focal deficits, GCS 15 E: No signs of injury O: Onset: Chest hurts for several days P: Pain: Provoked by cough and exertion; he has a hard time catching his breath

whenever he gets up and walks. Q: Quality: Burning, pressure R: Region: Substernal, some radiation to shoulders S: Severity: 3-8 out of 10 T: Time: Pressure and SOB last almost all day, exacerbations with exertion last 15

to 30 minutes

Detailed physical exam:

Neck: Jugular venous distention supine Lungs: Diminished breath sounds with occasional end expiratory wheeze with

deep breaths Cardiac: Distant heart sounds, no murmurs, S

3gallop rhythm

Abdomen: Distended with palpable spleen and liver Neurologic: No focal deficits

Key Questions

What is your general impression of this patient?


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Categorize this patient into one of the following categories:

Stable Respiratory Distress Respiratory Failure Shock Primary CNS Dysfunction Cardiopulmonary Failure/Arrest

What are your initial management priorities?

Immediate oxygen support Cardiac and oxygen saturation monitoring

Core Knowledge PointsGeneral ImpressionThe child is in respiratory distress and cardiogenic shock.

Patient appearance includes:

Thin, pleasant boy who seems tired but talks in complete sentences withoutdifficulty.

He is tachypneic with mild retractions. Slightly pale in color Dusky nail beds

Overall he demonstrates normal appearance, but increased work of breathing and signs of

shock.

Critical Actions

Check ABCs.Give oxygen by nonrebreather mask.

Obtain IV access.Check rhythm on cardiac monitor.

Obtain blood glucose, lab studies.Consider reducing preload and afterload with nitrates.

Consider diuretic therapy.He may need inotropic support.

Case Development

He may have an acquired cardiac problem due to a respiratory illness during winter

months causing secondary myocarditis.


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A second possibility is a congenital heart lesion that had been asymptomatic until thisillness, such as an anomalous coronary artery or valvular disease.

The child may have developed pericarditis.

Consider myocarditis in any child with:

Weakness SOB Chest pain Especially if associated with preceding prodromal viral illness Distant heart sounds: Silent Chest Enlarged heart on chest radiograph

Core Knowledge PointsDiagnostic Studies: Myocarditis

A chest radiograph will reveal cardiomegaly and prominent vasculature, perhaps even

pulmonary edema.

Laboratory studies may not add much and may be nonspecific.

Differential diagnoses include:

Pericarditis Hypertensive crisis Anomalous coronary artery and myocardial ischemia / infarction

Valvular disease Structural cardiac disease (e.g., VSD, ASD) Renal failure (e.g., glomerulonephritis) Rheumatic fever

Critical Actions

Management should include:

Gentle diuretic therapy Afterload reduction Possibly inotropic support Echocardiogram

Intrinsic cardiac lesion? Muscle hypertrophy? Pericardial effusion? Decreased contractility?


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Case Development

Myocarditis is a global infection/inflammation of the myocardium the degree to which

each child is affected is variable. Two potential courses of the disease are described.

Version 1:

A chest radiograph reveals cardiomegaly.

The echocardiogram reveals poor cardiac contractility.The diagnosis for this patient is myocarditis.

He is maintained on inotropes and pressor agents.He recovered to a point that he could be discharged 2 weeks later.

Will be followed closely for years to assess the degree to which he regains cardiacfunction

Version 2:A chest radiograph reveals cardiomegaly.The echocardiogram reveals poor cardiac contractility.

He is diagnosed with myocarditis.His condition deteriorated in the ED, and he suffered progressive shock.

He required inotropic support but developed ventricular tachycardia and ventricularfibrillation.

Talk students through the ventricular fibrillation algorithm. Discuss the AHA Guidelines

2000.

Extracorporeal membrane oxygenation (ECMO) is a last possibility to maintaincirculation until improvement or cardiac transplantation.

Core Knowledge PointsMyocarditis

Inflammatory disease of the myocardium includes:

Direct infection of the myocardium (e.g., viral myocarditis) Toxin production (e.g., diphtheria) Immune response as a delayed sequela of an infection (postviral or postinfectious

myocarditis)

A common type of myocarditis is acute rheumatic fever (ARF).

Core Knowledge PointsAcute Rheumatic Fever: Jones Criteria

A patient must have two of the major Jones criteria, or one major plus two minor criteriaof acute rheumatic fever plus documentation of an antecedent group A streptococcal

infection via serology or culture.


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Major criteria include:

Carditis: Most commonly valvulitis (mitral and aortic valve most common)diagnosed by auscultation (apical pansystolic murmur radiating to the axilla orsoft diastolic murmur at the base) or echocardiography.

Migratory polyarthritis Chorea Erythema marginatum Subcutaneous nodules

Minor criteria include fever, elevated CRP or ESR, prolonged PR interval, and arthralgia.

Core Knowledge PointsPericarditis

Pericarditis is an acute or chronic inflammation of the pericardial sac with an increase inthe pericardial fluid volume and pressure causing cardiac stroke volume reduction.

Between visceral and parietal pericardium is a fluid layer to help protect the heart and itscontractility. The usual fluid volume in the pericardial sac is 10 to 30 mL. When there is

a sudden increase in fluid, or constriction of the pericardial sac, chamber-filling volumeis restricted, which results in stroke volume reduction and hypotension (a process known

as tamponade). This increases the end-diastolic pressure in the ventricle, which impairsventricular filling and the ejection volume. Cardiac tamponade may require

pericardiocentesis.

The most common etiology is infectious, with approximately 30% resulting from abacterial cause. The most common viral etiology is Coxsackie virus. Other causes include

autoimmune disease, trauma, and neoplasms. The most common cause of constrictivepericarditis is tuberculosis. Other bacterial causes of pericarditis include pneumococci,

staphylococci, andHaemophilus influenzae pericarditis.

Clinical features:Clinically, the child may present with chest pain and respiratory distress.

If they have altered cardiac function from either an increase in pericardial fluid or

constriction of the pericardial sac, they will present with signs of congestive heart failureas well as a precordial knock or rub (like the sound of shoes walking on snow).

The classic signs include exercise intolerance, fatigue, jugular distension, lower extremity

edema, hepatomegaly, poor distal pulses, diminished heart tones, and pulsus paradoxus.


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Core Knowledge PointsEndocarditis

Endocarditis, although uncommon, is increasing in incidence, mostly because children

are surviving their congenital heart disease with artificial valves and patches, as well asan increased frequency of patients with central lines for various therapies.

Endocarditis is an infection of the endothelial surface of the heart, with a propensity for

the valves.

Endocarditis may be caused by many different organisms, although 90 percent of casesare caused by gram-positive cocci. Althoughstreptococcus (e.g., Streptococcus viridans)

is the most common organism involved, infections with Staphylococcus aureus,Streptococcus pneumoniae, or group A hemolytic streptococci can be more virulent.

Clinical features:Patients typically present with fever, tachycardia, and signs of cardiac failure ordysrhythmia with a history of recent cardiac surgery or indwelling vascular catheter.

Other signs include myalgias, heart murmur or petechiae, septic emboli, or splenomegaly.

They may present with signs indistinguishable from myocarditis with poor cardiac

contractility and inadequate perfusion with cool extremities, or symptoms similar topericarditis, with pain in addition to congestive heart failure.

Core Knowledge PointsKawasaki DiseaseKawasaki disease (mucocutaneous lymph node syndrome [MLNS]) was first described

by Kawasaki in 1967.

The etiology is unknown, but it is seen most often in children less than 5 years of age,during the winter and spring months, and with boys more susceptible than girls. There is

also a predilection for Asian and African children.

These patients may present with cardiac abnormalities that present in similar manner tochildren with decreased myocardial contractility, myocarditis, or coronary insufficiency.

The child may present or go on to develop congestive heart failure and shock with chestpain. Without treatment, 15% to 20% of children with Kawasaki disease will developcoronary artery aneurysms within 1 to 3 weeks from the onset of illness, which can

eventually lead to a myocardial infarction or ischemia-induced dysrhythmias.


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A child that presents with a myocardial infarction may have more nonspecific findingsthan an adult. They can present with nausea, vomiting, and abdominal pain. They may be

diaphoretic and crying, or asymptomatic.

Clinical features:Clinically, the child presents with a history of fever for 5 days or more. The diagnostic

criteria are the presence of conjunctivitis, cervical lymphadenopathy, gingivostomatitis,maculopapular exanthem (called polymorphous, which means that it can have many

different patterns), and swelling of the hands with erythema of the palms.

Polymorphous rash is often maculopapular, morbilliform, or erythema multiforme-like.

The Bottom Line Assessment of congenital heart disease can be challenging; however, applying

assessment skills with an understanding of normal physiology as well as

pathophysiology of cardiovascular disorders in children will assist the clinician inmanagement.

01 Cardiovascular I

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