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Cardiac Emergencies in Infants
Michael Luceri, DO
October 7, 2017
I have no financial obligations or
conflicts of interest to disclose.
Objectives
Understand the scope of congenital heart disease
Recognize the presentation of a critically ill neonate
Categorize the disease to facilitate its treatment
Background
Congenital heart defect (CHD)
– “A gross structural abnormality of the heart or intrathoracic great vessels that is actually or potentially of functional significance” Mitchell, et al (Circulation, 1971)
– 8-10/1000 live births, ~1%
– About half require an intervention
Recent increased detection
Birth Prevalence of Congenital Heart Disease Worldwide: A Systematic Review and Meta-Analysis
J Am Coll Cardiol. 2011;58(21):2241-2247. doi:10.1016/j.jacc.2011.08.025
Time course of reported total congenital heart disease (CHD) birth prevalence from 1930 until 2010. The blue line shows the time trend, and the squares represent
the calculated birth prevalence values for each time period.
Total CHD Birth Prevalence Over Time
Congenital Heart Defects
Recent increased detection
– Improvements in echocardiography
Doppler
Fetal echocardiography
Transesophageal echocardiography
3D echocardiography
– Advanced non-invasive imaging
CT
MRI
No increase in disease severity!!!
Birth Prevalence of Congenital Heart Disease Worldwide: A Systematic Review and Meta-Analysis
J Am Coll Cardiol. 2011;58(21):2241-2247. doi:10.1016/j.jacc.2011.08.025
Time course of birth prevalence of the 8 most common CHD subtypes from 1945 until 2010. AoS = aortic stenosis; ASD = atrial septal defect; Coarc = coarctation;
PDA = patent ductus arteriosus; PS = pulmonary stenosis; TGA = transposition of the great arteries; TOF = tetralogy of Fallot; VSD = ventricular septal defect.
Birth Prevalence of CHD Subtypes Over Time
Birth Prevalence of Congenital Heart Disease Worldwide: A Systematic Review and Meta-Analysis
J Am Coll Cardiol. 2011;58(21):2241-2247. doi:10.1016/j.jacc.2011.08.025
Reported birth prevalence of the 8 most common CHD subtypes per continent. Distribution of subtypes within total CHD is mentioned as percentages above bars.
*Reported PS and TOF birth prevalence in Asia was significantly higher than in Europe (p < 0.001) and North America (p < 0.001). †Reported Coarc birth prevalence in Asia
was significantly lower than in Europe (p < 0.001). ‡Reported TGA and AoS birth prevalence in Asia was significantly lower than in Europe (p < 0.001), North America (p <
0.001) and Oceania (p < 0.001). §No data on TOF and AoS birth prevalence in Africa were available. Abbreviations as in Figure 4.
Birth Prevalence of CHD
Subtypes
Circulation
Fetal circulation
– Fetal lungs collapsed, alveoli filled with fluid
– High pulmonary vascular resistance (PVR), thus minimal pulmonary blood flow (Qp)
Ohm’s Law: V = I • R (Voltage = Flow • Resistance)
In hemodynamics: Pressure (gradient) = Flow • Resistance
– Flow = Pressure/Resistance
– Oxygenation from placenta via umbilical vein
– PFO & PDA shunt RL
Normal
Heart
Normal
Heart
w/PDA
Circulation
Neonatal circulation
– Hormones of labor cease production of lung liquid
i.e. Epinephrine, vasopressin, cortisol, etc.
– First breath and lung expansion
Remaining liquid absorbed
PVR decreases Qp increases
Functional closure of PFO & PDA
– Now pulmonary & systemic circulation in series!
Circulation
Certain lesions can interrupt serial blood flow:
– i.e. TOF, aortic stenosis, coarctation
– Transposition of the great arteries (TGA)
Newborn then depends on the presence of a shunt
– Balloon atrial septostomy
Balloon Atrial Septostomy
First interventional procedure: Rashkind Septostomy (1966)
No animal studies
Prone to material embolization
Circulation
Certain lesions can interrupt serial blood flow:
– i.e. TOF, aortic stenosis, coarctation
– Transposition of the great arteries (TGA)
Newborn then depends on the presence of a shunt
– Balloon atrial septostomy
– Prostagladins!!!
Very forgiving, almost foolproof!
When in doubt, try it out!
Usually 0.01 mcg/kg/min works, can go up to 0.1 mcg/kg/min
Watch for fever (14%), apnea (12%), and flushing (10%)
Presentation
Varies dependent upon cardiac lesion, though can include:
– Cyanosis
Peripheral/Acrocyanosis: common and benign
Central: always pathologic
– Incomplete oxygenation in the lung
– Abnormal hemoglobin
– Intracardiac shunting
Hyperoxia Test: – Measure pre-ductal (RUE) PAO2 in room air
– Measure again after 5-10 minutes of 100% FiO2
– Strongly consider cyanotic heart disease if PAO2 is <150 mmHg
– Caveat #1: PPHN may also have PAO2 <150 mmHg!
– Caveat #2: Hyperoxia can close a PDA that might be needed!
Presentation
Varies dependent upon cardiac lesion, though can include:
– Murmur
– Tachycardia
– Respiratory distress
Tachypnea, retractions
– Poor feeding and/or inadequate weight gain
Irritability or sweating with feeds
– Shock
Gallop, HSM, poor capillary refill, pallor, weak pulses
Classification
Transposition of the great arteries
Obstructed systemic perfusion
Obstructed pulmonary blood flow
Single ventricle lesions
Heart failure
Transposition of the Great Arteries (TGA)
5-7% of all CHD
Male/female ratio ~3:1
Blood must mix via ASD, VSD, or PDA
Transposition of the Great Arteries (TGA)
Presentation
– 1 day old term male infant with poor feeding & severe cyanosis
– PE: tachypneic, symmetric pulses, single S2, no murmur, no HSM
– “Reverse differential cyanosis”
– ECG: RVH (normal)
– CXR: normal cardiac size, increased pulmonary vascularity
– Hyperoxia Test: PAO2 = 42 mmHg on 100% FiO2
Treatment
– Cath: Emergent balloon atrial septostomy
– Surgical repair: Atrial vs Arterial Switch
Transposition of the Great Arteries (TGA)
Mustard (“Atrial Switch”)
Transposition of the Great Arteries (TGA)
Jatene Procedure (“Arterial Switch”)
Classification
Transposition of the great arteries
Obstructed systemic perfusion
Obstructed pulmonary blood flow
Single ventricle lesions
Heart failure
Obstructed systemic perfusion
Examples include:
– Coarctation of the aorta
Obstructed systemic perfusion
Examples include:
– Critical aortic stenosis
Obstructed systemic perfusion
Examples include:
– Interrupted aortic arch
Obstructed systemic perfusion
Systemic flow is critically compromised when PDA closes
If untreated, will lead to shock and eventually death
Ductal-dependent
– PDA will allow for right to left shunting
Obstructed systemic perfusion Presentation
– 3 day old term infant acutely develops feeding and breathing difficulties
– PE: tachypneic, tachycardic, murmur, gallop, HSM, poor capillary refill and pulses
– Dusky appearance
– ECG: RVH
– CXR: cardiomegaly, increased pulmonary vascularity
– Hyperoxia Test: PAO2 = 180 mmHg on 100% FiO2
Treatment
– Rx: PGE1 infusion; inotropic support; NO Afterload Reduction!
– Eventual catheter-based and/or surgical intervention
Classification
Transposition of the great arteries
Obstructed systemic perfusion
Obstructed pulmonary blood flow
Single ventricle lesions
Heart failure
Obstructed pulmonary blood flow
Examples include:
– Tetralogy of Fallot
Obstructed pulmonary blood flow
Examples include:
– Critical pulmonic stenosis
Obstructed pulmonary blood flow
Acute and marked cyanosis
May have adequate perfusion initially (especially if atrial level communication)
Severe cyanosis can induce shock due to limited systemic O2 delivery that alters myocardial function
Ductal-dependent
– PDA will allow for left to right shunting
Obstructed pulmonary blood flow Presentation
– 1 day old term infant initially feeds well and appears healthy, then acutely becomes cyanotic
– PE: tachypneic, increased work of breathing, tachycardic, murmur
– Severely cyanotic
– ECG: RVH
– CXR: decreased pulmonary vascularity
– Hyperoxia Test: PAO2 = 30 mmHg on 100% FiO2
Treatment
– Rx: PGE1 infusion; sedation, preload, B-blockers, phenylephrine, Avoid inotropes!
– Eventual catheter-based and/or surgical intervention
Classification
Transposition of the great arteries
Obstructed systemic perfusion
Obstructed pulmonary blood flow
Single ventricle lesions
Heart failure
Single ventricle lesions
Examples include:
– Tricuspid atresia
Single ventricle lesions
Examples include:
– Hypoplastic left heart syndrome
Single ventricle lesions
Initial presentation as glorified ductal-dependent lesions
– Tricuspid Atresia*: Ductal-dependent pulmonary circulation
– HLHS: Ductal-dependent systemic circulation
Small/underdeveloped ventricle cannot serve as a functional pumping chamber
Must undergo staged repair culminating in a Fontan circulation
* Assuming normally related great vessels
Single ventricle lesions Presentation
– Rapid onset with ductal closure
– Often no murmur!
– Ductal-dependent systemic circulation
Reduced cardiac output
Metabolic acidosis
Profound shock
Respiratory failure
– Ductal-dependent pulmonary circulation
Profound cyanosis
– ECG & CXR: Variable
– Hyperoxia Test: PAO2 < 150 mmHg on 100% FiO2
Single ventricle lesions Treatment
– Rx: PGE1 infusion!
Manipulate SVR with systemic vasodilators
– i.e. Milrinone and Nipride
Manipulate PVR with ventilatory strategies
– Hypoxic gas admixture (FiO2 18%)
– Controlled respiratory acidosis
Optimize hematocrit
– Eventual catheter-based and/or surgical intervention
Stage 1: Norwood Procedure with Blalock-
Taussig (BT) Shunt or Sano (RV-PA) Conduit
Stage 2: Glenn Procedure
SVC connected to pulmonary arteries
Stage 3: Fontan Procedure
IVC connected to pulmonary arteries
Classification
Transposition of the great arteries
Obstructed systemic perfusion
Obstructed pulmonary blood flow
Single ventricle lesions
Heart failure
– Volume overload
Heart failure: volume overload
Examples include:
– Ventricular septal defect
Heart failure: volume overload
Examples include:
– Atrioventricular septal defect
Heart failure: volume overload
Examples include:
– Patent ductus arteriosus
Heart failure: volume overload
Left to right shunting results in “pulmonary overcirculation”
– Wasted of ineffective blood flow
Degree of shunting depends on PVR/SVR ratio
Heart failure: volume overload Presentation
– 3 month old infant with chronic feeding difficulties, failure to thrive, history of respiratory difficulties/pneumonia
– PE: tachypneic, retractions, single loud S2, murmur, HSM, symmetric pulses
– ECG: Biventricular hypertrophy
– CXR: cardiomegaly, hyperinflation, congestion, increased pulmonary vascularity
Heart failure: volume overload
Heart failure: volume overload Treatment
– Diuretics
– Inotropic support
– Optimize O2 carrying capacity
– Manipulate PVR/SVR ratio
Systemic vasodilators (i.e. ACE-inhibitors)
Optimize hemoglobin to balance circulation
Ventilatory strategies to increase PVR
– Eventual catheter-based and/or surgical intervention
Ventilatory strategies to manipulate Qp/Qs ratio
Treatment PVR SVR Qp/Qs Ratio
Reduce FiO2 Increase Decrease Decrease
Increase CO2 Increase Decrease Decrease
Reduce pH Increase Decrease Decrease
PEEP Increase Decrease Decrease
Summary
Congenital heart disease is relatively common
Cardiac emergencies are rare
Recognize symptoms early and keep a high index of suspicion
Attempt to categorize the suspected lesion according to presentation and testing results
When in doubt, start PGE1 infusion!