DISORDERS OF THE CARDIOVASCULAR SYSTEM PART 2 (AB) Flashcards
What are the five basic questions to answer for congenital heart disease (CHD) diagnosis?
- Is it acyanotic or cyanotic? 2. Is the pulmonary blood flow (PBF) normal, increased, or decreased? 3. Does the malformation originate in the left or right side of the heart? 4. Which is the dominant ventricle? 5. Is pulmonary hypertension present (Eisenmenger Syndrome) or not?
What are the basic diagnostics to request for cyanotic congenital heart disease (CHD)?
Chest X-ray (CXR), ECG, 2D-Echocardiogram, Cardiac Catheterization.
Why is an AP view taken for CXR in infants and children under 2 years old?
Infants and young children cannot stand on their own, so an AP view is taken instead of a PA view.
What is the significance of PA vs. AP view in CXR?
PA view: The film is closer to the chest, and the X-ray beam is from the back, making the heart size radiographically accurate. AP view: The heart appears enlarged due to its distance from the film.
What is the role of ECG in congenital heart disease (CHD) diagnosis?
ECG helps determine heart sidedness, chamber enlargement (RV or LV), and signs of atrial enlargement.
What is the definitive diagnostic tool for cyanotic CHD?
2D-Echocardiogram.
When is cardiac catheterization used in CHD diagnosis?
When ECG or 2D-Echo cannot fully determine anatomy, or in complex CHD cases where pulmonary artery location or pulmonary hypertension needs further assessment.
What is the hyperoxia test used for?
To differentiate between cardiac and pulmonary causes of cyanosis.
What are the steps of the hyperoxia test?
- Patient breathes 100% oxygen for 10 minutes (via hood or ET tube). 2. Oxygen tension is measured in the right radial artery (ABG needed, not pulse oximeter).
What PaO2 values indicate a cardiac vs. pulmonary cause of cyanosis?
PaO2 > 150 mmHg = Pulmonary cause (e.g., pneumonia). PaO2 ≤ 150 mmHg = Cardiac cause or persistent pulmonary hypertension of the newborn (PPHN).
What PaO2 value is seen in truncus arteriosus or single ventricle with PDA?
50 – 150 mmHg.
What PaO2 value is seen in Tetralogy of Fallot, tricuspid atresia, or other CHD with decreased PBF?
<50 mmHg.
What is the purpose of complex congenital heart disease (CCHD) screening?
To detect duct-dependent lesions and other complex congenital heart defects in newborns using pulse oximetry.
When is CCHD screening performed?
At or beyond 24 hours of life, or shortly before discharge.
What are the criteria for failing a CCHD screen?
Oxygen saturation <90% in right hand or foot = immediate referral. 90-95% or >3% difference = repeat test; if still abnormal, refer.
What are the four main components of Tetralogy of Fallot (TOF)?
- Pulmonary stenosis 2. Ventricular septal defect (VSD) 3. Overriding aorta 4. Right ventricular hypertrophy (RVH).
What determines the severity of TOF symptoms?
The degree of right ventricular outflow tract obstruction (RVOTO).
How does TOF typically present in infancy?
Cyanosis may not be apparent at birth but can develop around 6 months with increased activity.
What are the common triggers for hypercyanotic (Tet) spells in TOF?
Crying, feeding, defecating, or stressful procedures like IV insertion.
What is the first-line management for a Tet spell?
Place the child in a knee-chest position to increase systemic vascular resistance (SVR) and reduce right-to-left shunting.
What medications can be used to treat a Tet spell?
Phenylephrine (to increase SVR), propranolol (to reduce RVOTO spasm), and morphine (for hyperpnea and irritability).
What are the classic CXR findings in TOF?
Boot-shaped heart, concave main pulmonary artery segment, right-sided aortic arch, and decreased pulmonary vascularity.
What are the characteristic ECG findings in TOF?
Right axis deviation (RAD) >105° and right ventricular hypertrophy (RVH) with tall R waves in V1/V2 and deep S waves in V5/V6.
What is the definitive treatment for TOF?
Corrective open-heart surgery, ideally between 4-6 months of age.