Anesthesia for the Peds Patient with Congenital Heart Disease

Normal Parameters per age

Heart Rate ◦Infant relative bradycardia is <100/min ◦"Tachycardia" varies with age ◦120/ min in 18-month-old is NSR not ST Electrocardiogram ◦Rhythm not different than adult ◦Axis, t waves, r and s waves differ with age

Congenital Heart DiseasePhysiologic Classification of Defects

Several classification schemes have been proposed to characterize and categorize the various congenital cardiac defects, including: ◦categorizing structural defects into simple or complex lesions ◦considering the presence or absence of cyanosis ◦recognizing whether pulmonary blood flow is increased or decreased. A physiologic classification system can facilitate understanding of the basic hemodynamic abnormalities common to a group of congenital or acquired lesions and assist in patient management Cote suggests six broad categories according the underlying physiology or common features of the pathologies.

Genetic Diseases

Several relatively common chromosomal abnormalities can have cardiac manifestations. ◦Trisomy 18: 50% have congenital heart disease, 5% have atrioventricular canal defects ◦Trisomy 13: 80% have congenital heart disease ◦Trisomy 21: 50% have congenital heart disease; 50% of those have atrioventricular canal defects ◦Duchenne muscular dystrophy: 90% with abnormal EKG, cardiomyopathy, Heart failure and arrhythmias ◦DiGeorge syndrome → conotruncal abnormalities. ◦Williams syndrome → 80% have supravalvar aortic stenosis and peripheral pulmonary stenosis ◦Noonan syndrome → dysplastic pulmonary valve, hypertrophic obstructive cardiomyopathy Numerous metabolic diseases, can have cardiac involvement. ◦Cardiac involvement can manifest as cardiomyopathy, hypertrophic cardiomyopathy, storage of abnormal material in cardiac valves causing stenosis, or storage of material disrupting the normal conduction system. Prior to anesthetizing patients with genetic or metabolic disease-appropriate materials, literature and patient records should be reviewed preoperatively!!!!!

Inhalational Induction

Sevoflurane is the induction agent of choice for inhalational inductions in pediatric anesthesia. ◦It is associated with little myocardial depression or dysrhythmias, and there is a reduced likelihood of precipitating airway hyperreactivity than that observed with other inhalational agents. Little difference between volatile agents Nitrous oxide should be avoided for maintenance of anesthesia in children with CHD because of the risk of enlarging intravascular air emboli and the potential to increase the PVR.

Congenital Heart Diseases

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Incidence

-Congenital Heart Disease or CHD is the most common congenital anomaly ◦Incidence 1% or 10 per 1,000 live births ◦CHD is the leading cause of neonatal mortality ◦CHD is the most common congenital disease accounting for approximately 30% of all congenital diseases -S/S of CHD in infants and children often include dyspnea, poor feeding, poor growth, delayed physical development and the presence of a cardiac murmur -DX of CHD made during the first week of life in 50% of patients -Echo is the initial diagnostic step if CHD is suspected There are a seemingly bewildering number of nomenclature and classification systems used in congenital and pediatric cardiology.

Tetrology of Fallot

-VSD/ Overriding Aorta/ RVOT obstruction via RV muscle/ pulmonary valve/ RV hypertrophy -The R-L shunting across the VSD has both fixed and variable components. -The fixed component is determined by the severity of the RVOT obstruction -whereas the variable component depends on SVR and PVR »Early-can have left to right (pink TET) this is because ventricular hypertrophy has not yet developed. May not diagnose early d/t this. »Significant right to left occurs as they age, and the child become progressively more cyanotic »Dynamic shunting -The amount of obstruction they have varies like in an adult with hypertrophic cardiomyopathy. (ex give epi or ephedrine and worsen the outflow obstruction.) Tet spell- Cyanosis, shock -Loss of murmur

Demographics

62% not significant hemodynamic problems ©Defect: ©VSD-32% ©PDA-8% ©Pulm Stenosis (mod amount)-8% ©ASD-7% ANesthesia problem ©Coarctation-7% ©Transposition of the great arteries-3% ©Tetralogy of Fallot-3% ©Hypertrophic Left Heart-3%

Cardiac medications

Anticholinergics- atropine vs. glycopyrrolate ◦Child < 2 if they need something for HR use atropine. If you are reversing them glycopyrrolate is fine Inotropic Agents ◦Beta agonists- dopamine/ dobutamine/ epinephrine* ◦Dopamine & dobutamine do not work as well due to B-receptor downregulation. Epi or calcium works better ◦PDE inhibitors (Inodilators)- milrinone* Calcium infusion Vasopressors: vasopressin, (phenylephrine) ◦Most providers that work with children do not use phenylephrine under the teenage years. The reason for this is you're are dropping the child's cardiac output even if the B/P goes up this is not ideal! ◦One exception is tetralogy of Fallot Vasodilators: nitroprusside, (NTG) ◦Nitroprusside used when vasodilation is needed ◦Hardly ever use NTG. In an adult NTG in small doses will frequently cause hypotension. In children you can give very large doses without a noticeable response. In old days used to use it as a NO donor now have nitric oxide and it has fallen out of favor PGE A1 ◦Used to keep the ductus open when the CHD lesion is ductus dependent

CHARGE Syndrome

CHARGE syndrome is a genetic disorder characterized by congenital anomalies that include ◦Coloboma, ◦Heart defects, ◦choanal Atresia, ◦Retardation of growth and development, ◦Genitourinary problems, and ◦Ear abnormalities Cardiac defects occur in as many as 50% to 70% of children and commonly include conotruncal and aortic arch anomalies. Delayed growth and development usually results from cardiac disease, nutritional problems, and/or growth hormone deficiency.

Infective Endocarditis

CHD has become the primary risk factor for IE in children in developed countries. Risk is largely based on the nature of the cardiac condition. The infection results from deposition of bacteria or other pathogens on tissues in areas of abnormal or turbulent blood flow DX: Made with differing numbers of combinations of major & minor criteria. Major criteria: positive blood cultures & pathologic lesions on echo. Minor criteria include: -splinter hemorrhages, Janeway lesions (small painful nodule on the finger)s -Roth spots (retinal hemorrhages with clear centers) The presentation of the disease can be acute or subacute. S/S: new or changing murmurs and signs of systemic embolization ◦Acute: high fever, myalgias, fatigue lethargy and shock ◦Subacute: low grade fever, malaise, anemia, fatigue or weakness TEE: Routinely done to assess for vegetations or other abnormalities Treatment Parenteral antibiotics are initiated after blood cultures are collected. In some cases, children with IE require surgical intervention. Failure of medical therapy (i.e., inability to clear the bacteremia), abscess formation, refractory heart failure, large vegetation, and serious embolic phenomenon are indications for surgical intervention.

Pulmonary Hypertension

Cardiac ◦Long term increases in pulmonary blood flow ◦VSD/ AVSD/ PDA ◦Obstruction to pulmonary venous blood flow ◦Total anomalous pulmonary venous return Other: ex. Idiopathic (ex NICU babies with chronic lung disease), BPD/ pulmonary disease Right ventricular dysfunction, progressive cyanosis Þ inadequate oxygen delivery/ shock

Hypertrophic Cardiomyopathy

Characterized by ventricular hypertrophy without an identifiable hemodynamic cause that results in increased myocardial wall thickness ◦Heterogenous group of disorders. Examples include ◦Genetic defects (most common cause of sudden death in athlete) ◦Outflow tract obstruction Accounts for 40% of cardiomyopathies in children S/S: heart murmur, syncope, palpitations, or chest pain EKG: meets criteria for LVH in most children ECHO: a hypertrophied, nondilated LV is diagnostic Therapies range from longitudinal observation with medical management of heart failure and arrhythmias to cardiac transplantation Medical: Maintain adequate ventricular preload! (Esp in those with dynamic obstruction.) Diuretics are not indicated and can increase outflow tract obstruction. Inotropic agents and calcium infusions are not well tolerated. ◦β-Blockers and calcium channel blockers are the primary drugs for outpatient therapy. Surgical Cardioverter-defibrillators, surgical myotomy, transcatheter alcohol septal ablation and cardiac transplantation

Anesthesia Concerns : Right to Left Shunts

Chronic hypoxemia leads to compensatory polycythemia →↑ O2 carrying capacity HCT of greater than 65% are not uncommon. This leads to increased blood viscosity tissue hypoxia and increased SVR & PVR. Children may also develop venous thrombosis, strokes and cardiac ischemia (decreased plasma possible coagulopathy) Anesthetic goals ◦Maintain intravascular volume and SVR ◦Increases in PVR such as might occur from acidosis or excessive airway pressures should be avoided ◦Ketamine is a commonly used induction agent b/c it maintains or increases SVR and therefore does not aggravate the R-L shunting. ◦Oxygenation often improves after induction of anesthesia

Infant with Heart Murmur

Classification •Innocent murmurs •usually soft, systolic ejection type, and not holosystolic in duration •often resolve by changing the child's hemodynamic state with maneuvers such as lying down or sitting up •Hemodynamically Insignificant These suggest Oh Oh!!! Diastolic or continuous murmurs Holosystolic murmurs Gallop Cyanosis Murmurs accompanied by a palpable thrill are always pathologic. If you see these send child for cardiac consult

Congenital Heart Disease: Anatomical Classifications

Congenital heart diseases (CHD) consist of defects in the cardiac architecture that interfere with: ◦venous drainage ◦septation of cardiac segments and their sequences ◦ regular function of valve apparatuses The normal heart can be divided into three segments: ◦Veins and atria ◦Ventricles ◦Great arteries ◦ The segments are connected to each other by two connecting cardiac segments or junctions ◦atrioventricular connection ◦ventriculo-arterial connection -Establishing the sequence of cardiac segments and the anomalies present are the prerequisite for planning a surgical repair.

Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM), is characterized by thinning of the left ventricular myocardium, dilation of the ventricular cavity, and systolic functional impairment The broad number of etiologies range from genetic or familial forms to those caused by infections, metabolic derangements, toxic exposures, and degenerative disorders. S/S: Tachypnea, tachycardia, gallop rhythm, diminished pulses, hepatosplenomegaly CXR: Cardiomegaly, pulmonary vascular congestion EKG Rhythm disorders (most likely cause of this D/O), dilated left ventricle with decreased systolic function Treatment Medical: aim is to stabilize the patient using afterload reduction, inotropic support, and gentle diuresis.(know!) ◦The infusion of large fluid boluses is poorly tolerated and can result in hemodynamic decompensation and cardiovascular collapse. ◦Surgery: some children's disease state remains stable or improves others eventually require cardiac transplantation

Patients with R to L shunt

ETCO@ becomes useless they get a large gradient between ET CO2 and PAO2. ◦May be as high as 20-point difference may need to draw a sample. (draw ABG) ◦This gradient may change during the case based on shunt

Best Ways to Adjusting PVR

Increase #1 Hypoxemia Hypercapnia acidosis alpha agonists increased intrathroacic presure (PEEP) Decrease #1 hyperoxia hypocapnia alaklosis PGE1/PGI2 Inhaled NO

Kawasaki Disease

Kawasaki disease is a fairly common and potentially fatal form of systemic vasculitis of unknown origin.9 It's a condition seen predominantly in infants and young children. The disease can affect the coronary arteries resulting in dilation and aneurysmal formation The diagnosis relies on clinical features. To meet criteria, a child must have persistent fevers and at least four of the following findings: ◦Polymorphous exanthem ◦Peripheral extremity changes (e.g., erythema, desquamation, edema of the hands or feet) ◦Bilateral, nonexudative conjunctivitis ◦Cervical lymphadenopathy (often unilateral) ◦Oral changes (i.e., strawberry tongue; red, dry, or cracked lips) Intravenous gamma globulin (IVIG) and high-dose aspirin are recommended during the acute phase of the disease. In children with coronary artery aneurysms, low-dose aspirin therapy is administered, in some cases in combination with anticoagulants or antiplatelet drugs. Myocardial ischemia and infarction, although uncommon, are important potential complications. Anesthetic care in these children requires careful consideration regarding myocardial oxygen demand and supply; on rare occasions, coronary revascularization may be necessary.

Obstruction to Systemic Blood Flow

Left heart obstructive lesions lead to decreased systemic flow. ◦This condition is characterized by ductal-dependent systemic blood flow. ◦The PDA supplies systemic blood flow by shunting blood from the pulmonary artery to the aorta. ◦There is a Left-to-right intracardiac shunt with secondary pulmonary over-circulation. Several lesions are associated with systemic outflow tract obstruction. ◦critical aortic stenosis, severe aortic coarctation, aortic arch interruption, and hypoplastic left heart syndrome. Treatment ◦Medical: Prostaglandin E1 therapy maintains ductal patency and ensures adequate systemic blood flow until surgical or transcatheter intervention is performed in the first few days of life to relieve the systemic outflow obstruction. ◦Inotropic and/or mechanical ventilatory support are often necessary in the affected neonate/small infant ◦d/t increased pulmonary blood flow , frequently require diuretic therapy and manipulation of the systemic and pulmonary vascular resistances to control blood flows.

Fontan physiology

Management goals: ◦Preload: Provide systemic venous return ◦Prevent elevations in pulmonary artery pressure ◦Aggressively treat dysrhythmias to achieve AV synchrony Spontaneous ventilation is preferred ◦Improved venous return ◦Decreased pulmonary artery pressure

Cardiomyopathies

Most common types in children are ◦hypertrophic ◦Dilated or congestive ◦restrictive May also be classified as primary and secondary. ◦Primary: predominantly due to genetic mutation ◦Secondary: are those with systemic involvement in other organ systems Ex. Neuromuscular disorders such as Duchenne

Treatment: pulmonary hypertensive crisis

Oxygen!!! Oxygen!!! Oxygen!!! Treat acidosis (metabolic/ respiratory) Fluid bolus for left side of heart Determine cause of Pulmonary HTN ◦Decrease noxious stimuli, too light? Decrease catecholamine surge!! opioid ◦Pulmonary vasodilator-iNO, Prostacyclin ◦Support cardiac output- ? Milrinone (be careful d/t may cause hypotension) Persistent hypotension ◦Vasopressor = 2 edge sword. ?Vasopressin vs epi or norepi (d/t these meds cause the pulmonary vasculature to increase pressure even further.)

Parallel Circulation

Parallel circulation occurs in conditions such as transposition of the great arteries. A condition in which the aorta and pulmonary artery are reversed. ◦normal blood pattern: body-heart-lungs-heart-body. Blood flow cycle is split in two ◦body-heart -body (without being routed to the lungs for oxygen) or ◦lungs-heart-lungs (without delivering oxygen to the body) Mixing of blood in this setting can occur at the atrial, ventricular, or ductal levels Treatment Although prostaglandin E1 therapy maintains ductal patency and enhances intercirculatory mixing, balloon atrial septostomy to create or enlarge an existing restrictive interatrial communication, allowing for or augmenting mixing, is necessary in some infants. Mixing at the atrial level is considered much more effective than at the ventricular or ductal levels.

Heart Failure in Children

Pediatric heart failure results from markedly different etiologies from those reported in adults. The causes of heart failure in children vary with age. In the perinatal period, ◦cardiac dysfunction can be related to birth asphyxia, sepsis or constitute an early presentation of CHD. ◦The neonate with heart failure frequently presents with clinical signs of a low cardiac output state. First year of life ◦predominantly caused by structural heart disease (problem with heart tissue or valves. Many are congenital). Other causes include metabolic cardiomyopathies or acute events such as myocarditis. ◦In infants with heart failure, tachypnea, dyspnea, tachycardia, feeding difficulties, and failure to thrive are prominent features. ◦The physical examination can display grunting respirations, rales, intercostal retractions, a gallop rhythm, and hepatosplenomegaly. Frequently, a mitral regurgitant murmur is present. Beyond the first year of life ◦Consequence of previous surgical interventions, unrepaired CV disease, cardiomyopathies, myocarditis or chemotherapy ◦Older children with heart failure exhibit exercise intolerance, fatigue, and growth failure

Premedication

Premedication ◦Unnecessary if infant < 6mo or child with little anxiety ◦Necessary in older children especially if have a prior surgical history with associated fears ◦in children with severe congestive heart failure premeds are probably best used judiciously, if at all ◦children with dynamic obstruction to the left or right ventricular outflow tracts often benefit from sedative premedication because crying and struggling during induction may worsen obstruction. ◦ Cyanotic children (e.g., those with tetralogy of Fallot [TOF]), may develop increasing cyanosis if agitated during induction. ◦it is important to monitor cyanotic children after premedication and provide supplemental oxygen as needed because they exhibit a blunted ventilatory response to hypoxia Versed is most commonly used but numerous other meds including ketamine and precidex have been used.

Obstruction to Pulmonary Blood Flow

Right heart obstructive lesions lead to decrease pulmonary flow. ◦This condition is characterized by ductal-dependent pulmonary blood flow. ◦The PDA supplies pulmonary blood flow by shunting blood from the aorta to the pulmonary artery. ◦ There is a right-to-left intracardiac shunt. Critical pulmonary valve stenosis and pulmonary atresia with intact ventricular septum, are anomalies that rely on patency of the ductus arteriosus for pulmonary blood flow. Treatment Affected infants frequently require prostaglandin E1 infusions for management of their cyanosis until the pulmonary outflow obstruction is relieved or bypassed.

Congenital Heart DiseaseShunting Classification

Right to Left Shunt (Cyanotic) Lesions in this group (also called mixing lesions) often produce both ventricular outflow obstruction and shunting. The obstruction favors shunt flow towards the unobstructed side. When the obstruction is mild, the shunting is affected by the SVR to PVR ratio, but increasing degrees of obstruction "fix" the direction and magnitude of the shunt Tetralogy of Fallot (most common R-L shunt), includes RV outflow track obstruction, RV hypertrophy, VSD with an overriding aorta High resistance to pulmonary blood flow leads to a decrease in pulmonary blood flow. Children develop hypoxemia and cyanosis A right-to-left shunt allows deoxygenated systemic venous blood to bypass the lungs and return to the body. Resulting in decreased oxygen content of the systemic arterial blood

Single-Ventricle Lesions

Single ventricle heart defect is the general name for many types of heart defects that result in in having one functional ventricle. In some cases, one of the ventricles is hypoplastic. In other situations, one of the valves that lets blood enter into the ventricles is missing (atresia) or does not let much blood go across it (stenosis). Some of the specific types of single ventricle congenital heart defects include: tricuspid atresia with ventricular septal defect, double inlet left ventricle, unbalanced atrioventricular septal defect, hypoplastic left heart syndrome. A common features of these lesions: complete mixing of the systemic and pulmonary venous blood at the atrial or ventricular level. ◦Another frequent finding is aortic or pulmonary outflow tract obstruction. R→L shunt at ductal level: Ductal dependent systemic flow!!! An important goal in single-ventricle management involves optimization of the balance between the pulmonary and systemic circulations early in life. This is a critical issue because low pulmonary vascular resistance and limitation of the ventricular volume load are prerequisites for later palliative strategies and optimal outcomes in these children.

Why worry about murmurs? (Dr. Fried)

Some kids have shunts ◦Paradoxical air embolus (may cause air to go to coronaries and MI or go to brain) ◦Pulmonary edema ◦Hypoxemia Outflow obstruction/ myocardial dysfunction/ shock Unidentified coarctation of aorta place O2 on baby and cause closure of shunt with resulting shock SBE (sbacute bacterial endocarditis) prophylaxis

Rheumatic Fever and Rheumatic Heart Disease

Still occurs infrequently in US but is leading cause of death r/t acquired cardiac disease in developing countries. ◦Cause group A β-hemolytic Streptococcus or Streptococcus pyogenes Valvulitis is the most common cardiac problem but is often mild during the primary event. The mitral valve is most commonly affected, followed in incidence by the aortic valve, with tricuspid or pulmonary valve involvement much less common. Treatment of acute disease is with aspirin Following an initial episode of acute rheumatic fever, patients receive monthly long-acting penicillin intramuscularly, which has been shown to be more effective than oral prophylaxis.

Cavopulmonary Anastomosis Stage 2 (Glenn), Stage 3 (Fontan)

Takes place a 6 months In stage 2: Usually takes place at 6 months old. The shunt is removed, the SVC is then "plugged directly into the pulmonary artery. Now blood is coming from the svc directly to the pulmonary artery not the right atrium. The R. atrium is then closed off at the site of the SVC insertion In stage 3: Completed when the baby is 2-4 years old. The IVC is taken down from the atrium and plugged into the pulmonary artery. Now all of the venous drainage is going directly to the lungs , bypassing the whole right side of the heart. This heart now functions as a two-chamber heart and blood flow to the lungs is passive. Pulmonary blood flow& ventricular preload is passive circuit (PAP-CVP gradient) CVP monitor = PAP, not preload 3 big potential problems ◦Increased PVR (part of the reason for stage 1) ◦Atrial dysrhythmias ◦AV valve regurgitation

Stage 1: Norwood (BT)/ Sano (RV-PA)

The most pressing issue with hypoplastic L. Heart syndrome is an inability to pump blood to the body This procedure is performed in the neonatal period to establish both pulmonary and systemic blood flow ©Very high risk for sudden death ©The goal of the Norwood is to connect the RV to the systemic circulation by performing an aortic reconstruction, open the atrial septum to make a single common atria, then place a shunt to connect the RV to the pulmonary arteries ©Balance of PVR/SVR. Single pump with 2 faucets. Balance flows in each faucet to assure systemic CO and PBF. ©Use SPO2 to estimate PVR/SVR ratio ©SpO2 75-85 optimal ©SPO2 90's too high- low CO

Anesthesia for Children Undergoing Heart Surgery Preoperative Visit and Evaluation

These children require a thorough preoperative evaluation and an assessment of several perioperative challenges including ◦cyanosis ◦intracardiac shunting ◦impaired hemostasis Medical Assessment ◦Type of CHD and coexisting diseases ◦Review history from the medical record. Particular attention should be paid to the imaging (cardiac cath/echo, CXR), EKG and lab data (Hgb polycythemic?, K, Bun/Cr) ◦Need to know the Age (may manage the same lesion differently in newborn vs. Infant vs. child), lesion type, effects of CHD on other organs, associated anomalies, preoperative condition and procedure (lap chole vs spine procedure) ◦Must know the presence and degree of cardiac failure, cyanosis, or risk of pulmonary HTN. ◦Nutritional state of the child should be evaluated as poor growth and development may be a sign of sever CHD ◦Prior surgical interventions? (redo sternotomy) ◦Will the planned procedure impact where I can place my arterial live or IVs? ◦ROS: Cyanosis, respiratory, sweating, poor feeding, syncope, liver or renal dysfunction ◦Medications: Prostaglandin E1, Digoxin, ACE inhibitors, diuretics

Tetralogy of Fallot

Treatment If R side can not pump out blood d/t PVR or valve thickening it will lead to decreased volume on the left side. ◦Give O2 (which may or may not help) ◦Fluids- to increase CVP (b/c you want to drive volume into the L side of the heart) ◦Increase afterload (d/t if SVR goes up L ventricular pressure goes up forcing the R-L shunt to decrease) ◦Legs up/ squeeze legs (Increases SVR) ◦Phenylephrine (5 mcg/kg) (draw up for tet babies) ◦Reduce catecholamines !!! Sedation- opioid ◦Reduce contractility- esmolol ◦Both narcotics and esmolol can cause hypotension so be careful.

Single Ventricle Physiology

Unique physiologic abnormalities ◦A group of defects that are characterized by aortic valve atresia and marked under development of the left ventricle. ◦The right ventricle is the main pumping chamber for both systemic and pulmonary circulations ◦It ejects normally into the pulmonary artery and all (or nearly all blood flow entering the aorta is usually derived from a PDA)

Volume Overload Lesions

Volume Overload Lesions Typically caused by left-to-right shunting at the level of the atria, ventricles, or great arteries. ◦If the location of the shunt is proximal to the mitral valve right heart dilation occurs ◦Lesions distal to the mitral valve lead to left heart dilation The magnitude of the shunt and resultant pulmonary-to-systemic blood flow ratio (Q̇pulm/Q̇sys) ◦ dictate the presence and severity of the symptoms ◦guide medical and surgical therapies. Treatment Medical: Diuretic therapy and afterload reduction are beneficial in controlling pulmonary over circulation and ensuring adequate systemic cardiac output. Surgical: may be required to address the primary pathology

Restrictive Cardiomyopathy

least common of the major types of cardiomyopathies (5%) and portends a poor prognosis when it manifests during childhood characterized by diastolic dysfunction related to a marked increase in myocardial stiffness resulting in impaired ventricular filling; most cases are thought to be idiopathic S/S are usually nonspecific and primarily respiratory occasionally dx after syncopal or sudden near-death event ECHO: Severe atrial dilation and normal or small-sized ventricles. Secondary pulmonary hypertension Children with RCM are prone to thromboembolic complications and anticoagulation therapy is frequently recommended. Treatment Medical: Controversial b/c no specific agent or strategy has been shown to significantly alter outcomes ◦No diuretics as this robs the patient of needed preload. No inotropic agents b/c systolic function is preserved and the arrhythmogenic properties of inotropic agents can induce a terminal event Surgical: Cardiac transplant

Acquired Heart Disease

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Left Ventricular Outflow Lesions

©Coarctation, Aortic stenosis ©Treat like adults ©Don't want high heart rate, assure preload is ok ©The exception: Neonates with these disorders are living off their Ductus No 100% O2 you will close the Ductus!!! ©B/P's can be widely different in left (90) vs right (85) arm and legs (40) d/t coarctation near L subclavian ©So say you are measuring SBP in the legs and see a reading of 60 from your cuff and start vasopressors. SBP in brain may be 170 ©Balance!!! b/p needs to be high enough for the kidneys but not so high that you cause a brain bleed ©Neonate: PGE dependent- Watch PVR/SVR ratio ©Infant/ older Child ◦Coarctation: Hypertension to head, renal hypoperfusion ◦Maintain BP near patient's normal -measured in RUE ◦Aortic stenosis: really no different than adult

Pediatric Heart Failure(Dr. Fried)

©Elevated sympathetic tone in children with heart failure d/t CHD leads to Beta receptor down-regulation ©Do better with calcium and milrinone vs dopamine and dobutamine ©Kids can get Ischemia usually results from: ©Ventricular hypertrophy: with significant increase in wall thickness more O2 consumption ©Kids tend to be tachycardic ©Low diastolic pressure (due to shunts) ©Hypoxemia ©Hyperviscosity

Prostaglandin Dependent Lesions(Limited Pulmonary Blood Flow)Dr. Fried

©In children with CHD, blood flow has 2 choices can go systemic or lung (like a garden hose with 2 nozzles on it) ©How much flows where depends on vascular resistance ©Your job is to balance this ©This can be determined by your pulse ox. A balanced blood flow will have O2 Sats in the mid 80s approx 85% ©If Sats are 99% the child will develop heart failure d/t too much pulmonary flow ©If Sats are 60% cardiac output will be better, but child would be cyanotic ©You can manipulate this with what you do; manipulate PVR with © 1. O2 (best) may keep as low as 21% in some cases shoot for mid 80s sat © 2. Co2 (adjust acid base balance as needed) ©Precarious balancing act-pulmonary blood flow ©Minimize FiO2 to decrease risk of ductal closure and prevent pulmonary flooding

Anesthesia Concerns : Left to Right ShuntsDr Freid

©In the absence of heart failure, anesthetic responses to IV and inhalational agents are generally not significantly altered. M&M pg. 430 ©Volatile agent and positive pressure ventilation does what you need! ©Adjustment of PVR/ SVR ratio-low Fi02, PEEP, normocapnea or mild hypercapnea ©Note: large increases in SVR should be avoided b/c they may worsen the L-R shunt. ©Risk for CHF. Normal preload, watch fluid intake

Congenital Heart DiseaseShunting Classification

©Left to Right Shunts (Acyanotic) ©Simple shunts are isolated abnormal communications between the R & L sides of the heart. ©VSD, ASD, AV canal (AVSD), PDA ©Depending on the size and location of the communication, the right ventricle may also be subjected to the higher left-sided pressures resulting in both pressure and volume overload ©Too much pulmonary blood flow! ©Large increases in pulmonary blood flow produce pulmonary vascular congestion and increase extravascular water. The latter interferes with gas exchange, increases airway resistance, and decreases lung compliance ©Volume hypertrophy (LVH, LVH /RVH) ◦Dependent on lesion ©When a communication is small, shunt flow depends on the size of the communication. When the communication is large the shunt flow depends on the relative balance between PVR and SVR. An increase in SVR relative to PVR favors L - R shunting , whereas an increase in PVR relative to SVR favors R-L shunting. ©Pulmonary blood flow dependent on PVR/ SVR ratio ©Eventual pulmonary hypertension ◦Faster in trisomy 21

Agents

©Opioids have little effect on PVR/ SVR unless rigid chest causes hypoxemia ®Remifentanil theoretical advantage in some lesions/ procedures ©Ketamine may increase PVR in pulmonary hypertension ©Little difference between volatile agents

Effect of Shunt on Induction

©Right to left shunt ◦Theoretically, slows inhalation induction b/c the blood bypasses the lung with minimal concentrations in the blood ◦Affects least soluble agents: N2O/Sevo/ Des ◦Clinically- minimal slowing of anesthetic induction ◦The reason you don't always see this is because many of these kids have depressed Cardiac output, this results in an increased FA/FI (increased rate of rise) leading to a more concentrated level of agent in the lungs therefore leads to higher concentration in the blood which decreases induction time ◦Faster IV induction d/t fentanyl and propofol metabolized by the lung. If you bypass the lung it will slightly speed up induction ©Left to right shunt ◦Theoretically faster inhalation induction ◦No real clinical difference

Normal BP

• Easy to remember guides • Premature infant MAP (mm Hg) = GA+ age (weeks) • GA = gestational age (wks) •Ex: 31-week preemie 3 weeks old should have a mean pressure of 33-34 • Infant: systolic BP 60-70's under GA • • Lower limits SBP - over age 2-8 y/o: •70 mm Hg + 2 x age (years) •Ex. 3-year-old: 70 +2*3 = 76

Cyanosis

•Cyanosis •Prolonged preoperative fasting should be avoided in children who have cyanotic heart disease with increased erythrocytosis to avoid dehydration and further increase of already elevated hematocrit and blood viscosity. •Small infants with significant heart failure and failure to thrive can have inadequate glycogen reserves and are at risk for hypoglycemia if they fast for many hours. •Intracardiac Shunting •In CHD, much of the pathophysiology involves communications between chambers or vessels that are normally separate, resulting in shunting of blood between ventricles, atria, the great arteries, or a combination of these, depending on the nature of the lesion. •Management of shunting during anesthesia is a major concern that requires an understanding of the factors that control shunting.

Myocarditis

•Myocarditis is defined as inflammation of the myocardium, often associated with necrosis and myocyte degeneration. •In US, most common cause is viral infection •Myocarditis is highly suspected when a child presents with new-onset congestive heart failure or ventricular arrhythmias without evidence of structural heart disease. •ECG typically demonstrates low-voltage QRS complexes with tachycardia, which sometimes is ventricular in origin. •CXR: shows cardiomegaly with pulmonary vascular congestion. •ECHO: displays ventricular dilation with decreased systolic function, •Among children with heart failure, 1/3 will regain full ventricular function 1/3 will recover but continue to demonstrate impaired systolic function, and 1/3 will require cardiac transplantation. •Medical no specific therapies have been identified to directly treat myocardial injury. Current treatment includes diuresis and afterload reduction +/- immune modulation or suppression

Endocarditis Prophylaxis

•The risk for developing Infectious Endocarditis from transient bacteremia is extremely small in children with normal intracardiac anatomy •certain cardiac conditions are predisposed to acquiring endocarditis. •The American Heart Association guidelines do not recommend antibiotic prophylaxis based exclusively on an increased lifetime risk of endocarditis. •They propose that it should be restricted to those at greatest risk for an adverse outcome resulting from Infectious Endocarditis •The guidelines recommend the administration of antibiotic prophylaxis 30 to 60 minutes before the procedure to achieve adequate tissue concentrations of antibiotics before bacteremia occurs •The standard prophylactic regimen for children is for oral amoxicillin(know). For the child who is allergic to penicillin or ampicillin, oral alternatives include: cephalexin, clindamycin, azithromycin, clarithromycin.

Blalock-Taussig shunt(s)

◦Graft between the subclavian or innominate artery to pulmonary artery gortex shunt ◦This graft increases pulmonary blood flow for kids who do not have adequate flow ◦It's basically a Gortex PDA!! ◦BP measurements may be falsely low on shunt side, don't know? Use leg ◦Invasive, noninvasive BP monitoring should be avoided on that side