Cardiac emergencies and the Pediatrician

Thomas R. Burklow, MDAsst C., Pediatric CardiologyWalter Reed Army Medical CenterNational Capital Consortium

Cardiac emergencies

♥Congestive heart failure♥Hypercyanotic spells♥Tachyarrhythmias♥Hypertensive crisis

How do you know you are dealing with a cardiac

?emergency

Case Presentation #1

♥ 4 month old presents to ER with cc: “cold symptoms”

♥ 5 day history of increasing cough; afebrile, no rhinorrhea, no ill contacts.

♥ PMH: unremarkable. vigorous feeder (25-30oz/d) until the last couple of days.

♥ FHx: father had a “leaky valve” but was cleared to join the Marines

Physical Examination

♥ VS: HR 165, RR 60, normal BP throughout; RA O2 sat mid 80’s, increases to 97% on 1/4 L/ O2

♥ Small for age male, nondysmorphic, mild cyanosis, moderate increased work of breathing

♥ Left chest prominent♥ Prominent PMI, RRR, S2 obscured by murmur, gr III

pansystolic SRM over apex to left axilla♥ Liver edge 4 cm below RCM♥ 1+ pulses throughout

Electrocardiogram

Chest X ray

What is the pathological condition which is present in this infant?

What information supports this supposition?

What do you do?

Clinical manifestations

♥ Infant➣ feeding difficulties

➣ failure to thrive➣ diaphoresis➣ tachycardia➣ tachypnea

♥ Child➣ breathlessness➣ tachycardia➣ tachypnea➣ peripheral edema➣ cardiomegaly

What causes congestive heart failure?

♥Excessive work load: pressure or volume

♥Normal workload faced by a damaged myocardium

Etiologies

♥ Neonate➣ dysfunction➣ volume➣ pressure

♥ Infant➣ Volume➣ Dysfunction

♥ Child➣ Palliated congenital heart disease

➣ AV valve regurgitation

➣ Acute rheumatic fever➣ Myocarditis➣ Endocarditis

Neonatal congestive heart failure

♥ Dysfunction➣ Myocarditis➣ Cardiomyopathy—think inborn error of metabolism➣ Coronary artery anomaly➣ Arrhythmias

♥ Volume➣ Unrestrictive ventricular septal defect(s)➣ Truncus arteriosus

♥ Pressure—think ductal-dependent left-sided obstruction

➣ Hypoplastic left heart syndrome➣ Critical aortic stenosis➣ Critical coarctation of the aorta

CHF in infants and children

♥ Dysfunction➣ Myocarditis➣ Cardiomyopathy—think inborn error of metabolism➣ Coronary artery anomaly➣ Palliated congenital heart disease➣ Arrhythmias

♥ Volume➣ Unrestrictive ventricular septal defect(s)➣ Severe atrioventricular valve dysfunction➣ Truncus arteriosus➣ Palliated congenital heart disease

How do you know what entity you are dealing with?...

♥ Age➣ An apparently well neonate who develops CHF at 1-2

weeks...consider a ductal-dependent lesion➣ An apparently well child without known heart disease

develops CHF… consider myocarditis♥ Fetal history of “irregular heart beats”♥ Duration of symptoms♥ Prior history of surgery♥ Family history♥ Travel history

Assessment--physical examination

♥ Identify signs and symptoms of congestive heart failure

♥ Blood pressures♥ Pulse oximetry♥ Presence of murmur MAY be helpful

Treatment

♥ Digitalis➣ oral: 8-10 mcg/kg/day➣ I.V.: 80% of oral dose➣ Because of varying metabolism, appropriate dose varies

by age➣ Rapid digitalization

➣ May be performed over 12-24 hours, 6-12 hours in dire situations

➣ Calculate TDD (varies by age); administer 1/2 of TDD, followed by 1/4, then 1/4 of TDD

♥ Case example: patient weight is 5.5 kg

Case example

♥ 5.5 kg in a 4 month old♥ Oral TDD for 1 month-2 years is 30-50 mcg/kg

➣ TDD is 220 mcg➣ Administer 110 mcg now, then 55 mcg in 12 hours, then

55 mcg in 6 hours➣ IV dose is 80% of the above amounts

♥ Maintenance digoxin is approximately 1/4 of TDD, divided b.i.d., or at 50 mcg/cc, 0.1 cc/kg per dose b.i.d.

Digoxin toxicity

♥ Levels are helpful only in cases of suspected toxicity, not for management

♥ GI symptoms are common presenting symptoms: nausea, vomiting, anorexia

♥ Most common sign of cardiac toxicity is arrhythmia: bradycardia, AV block, PVCs

♥ Treatment includes holding doses for 1-2 half lives, atropine for sinus bradycardia, and “FAB” fragments in cases of significant toxicity

Other medications

♥ Diuretics➣ Furosemide (Lasix); 0.5-1.0 mg/kg/dose➣ Chlorothiazide (Diuril); 20-50 mg/kg/day➣ Spironolactone (Aldactone); 1-2 mg/kg/day

♥ Afterload reduction➣ Captopril (Capoten); 0.1-0.5 mg/kg/dose t.i.d. ➣ Enalapril (Vasotec); 0.1 mg/kg/day

♥ Beta-blocker ➣ Labetolol➣ Carvediolol

A couple words regarding critical left sided obstructive lesion…

Critical obstruction to cardiac output

♥ Hypoplastic left heart syndrome♥ Critical aortic stenosis♥ Critical coarctation of the aorta

The common endpoint for these three lesions is loss of systemic cardiac output when the ductus closes… .

Physiology of hypoplastic left heart

STOP

Prostaglandin

♥ PGE1

♥ Powerful ductal dilator♥ Mechanism of ductal closure

➣ High oxygen tension➣ Circulating prostaglandins➣ Genetic predetermination

Prostaglandin dosing

Starting dose: 0.1 mcg/kg/min

Or…➣ One ampule is 500 mcg/1 cc➣ Mix one amp in 82 cc of normal saline➣ Run resulting mixture at 1 cc/kg/hr, this will be

equivalent to 0.1 mcg/kg/min

Case presentation #2

♥ Two month old African-american infant presents to the 2 month well baby visit

♥ Mother has no concerns: feeding well, no tachypnea.

♥ Family history is unremarkable

Physical Examination

♥ VS: HR 180; RR 25, BP 85/45, room air oxygen saturations 84%

♥ Ht 25th percentile, Wt 25th percentile♥ General features: non-dysmorphic infant

female ♥ Abdomen: Liver edge palpable at RCM♥ Ext: 2+ radial and femoral pulses

Cardiovascular examination

♥ Prominent right ventricular impulse, subxiphoid ♥ Normal S1 with a single S2♥ Harsh systolic murmur noted at the left mid-upper

sternal border, with radiation to back and axilla ♥ Diastole: quiet♥ Extra cardiac sounds: none

Electrocardiogram

Chest radiograph

While discussing the most likely diagnosis with the parents, you are called away. However, you are urgently called back to the examination room by the clinic nurse. The parents state that while the infant was crying, her complexion became intensely dark (“she’s never done this before”) and becamely listless…

The pulse oximeter is reading a HR of 170 and an pulse oximetry reading of less than 70%. Upon auscultation, you note the murmur is diminished in intensity.

?

Hypercyanotic spell

♥ a.k.a. “Tet spell”, “paroxysmal hyperpnea”♥ Etiology uncertain

➣ “Infundibular spasm”➣ Decrease in systemic vascular resistance

♥ Goal of therapy is to increase pulmonary blood flow

PVRPVR

SVRSVR

Recognition of hypercyanotic spell

♥ Symptoms include: irritability, crying, loss of consciousness

♥ Physical examination may demonstrate tachypnea, deepening of cyanosis, and loss of systolic ejection murmur

♥ Laboratory data would reveal metabolic acidosis

Treatment

♥ Soothing♥ Knee-chest positioning♥ Morphine, 0.1-0.2 mg/kg IV or SC♥ Oxygen (perhaps limited value)♥ Intravenous volume expansion, 10 cc/kg isotonic♥ Sodium bicarbonate 1-2 mEq/kg/dose♥ Propanolol, 0.15-0.25 mg/kg IV over 2-5 minutes♥ Phenylephrine, 0.1 mg/kg IM or SC♥ General anesthesia

The End…for now