5. Cardiology Flashcards
Describe: Prenatal circulation (1)
Describe heart before birth (2)
- shunting deoxygenated blood
- ductus arteriosus: connection between pulmonary artery and aorta
- shunting oxygenated blood
- foramen ovale: connection between right and left atria
- ductus venosus: connection between umbilical vein and inferior vena cava
Describe heart before at birth (5)
- with first breath, lungs open up -> pulmonary resistance decreases -> pulmonic blood flow increases
- separation of low resistance placenta -> systemic circulation becomes a high resistance system -> ductus venosus closure
- increased pulmonic flow -> increased left atrial pressures -> foramen ovale closure
- increased oxygen concentration in blood after first breath -> decreased prostaglandins -> ductus arteriosus closure
- closure of fetal shunts and changes in vascular resistance -> infant circulation assumes normal adult flow
Fetal circulation is designed so that oxygenated blood is preferentially delivered where? (2)
to the brain and myocardium
Describe epidemiology: Congenital Heart Disease Cardiology (2)
- 8/1000 live births have congenital heart defect (CHD), which may present as a heart murmur, heart failure, or cyanosis;
- ventricular septal defect (VSD) is the most common lesion
Describe investigations: Congenital Heart Disease Cardiology (2)
- Echo, ECG, CXR
- pre and postductal oxygen saturations, 4 limb BPs, hyperoxia test
Compare CYANOTIC VS. ACYANOTIC CONGENITAL HEART DISEASE (3)
- cyanosis: blue mucous membranes, nail beds, and skin secondary to an absolute concentration of deoxygenated hemoglobin of at least 30 g/dL
- acyanotic heart disease (i.e. L to R shunt, obstruction occurring beyond lungs): blood passes through pulmonic circulation -> oxygenation takes place -> low levels of deoxygenated blood in systemic circulation -> no cyanosis
- cyanotic heart disease (i.e. R to L shunt): blood bypasses the lungs -> no oxygenation occurs -> high levels of deoxygenated hemoglobin enters the systemic circulation s cyanosis
Name Common congenital heart diseases (figure)
- ASD: atrial septal defect
- VSD: ventricular septal defect
- PDA: patent ductus arteriosus
- TGA: Transposition of the Great Arteries
Name: Characteristic CXR Findings in congenital heart defect (3)
- Boot-shaped heart: tetralogy of Fallot, tricuspid atresia
- Egg-shaped heart: transposition of great arteries
- “Snowman” heart: total anomalous pulmonary venous return
Describe: LEFT-TO-RIGHT SHUNT LESIONS (3)
- extra blood is displaced through a communication from the left to the right side of the heart -> increased pulmonary blood flow -> increased pulmonary pressures
- shunt volume is dependent upon three factors: (1) size of defect, (2) pressure gradient between chambers or vessels, and (3) peripheral outflow resistance
- untreated shunts can result in pulmonary vascular disease, left ventricular dilatation and dysfunction, right ventricular HTN and RVH, and ultimately R to L shunts
Name 3 types of atrial septal defect
- ostium primum (common in DS, defect located at mitral or tricuspid valves)
- ostium secundum (most common type, 50-70%, defect located at septum between left and right atria)
- sinus venosus (defect located at entry of superior vena cava into right atrium)
Describe natural history: Atrial Septal Defect (2)
- 80-100% spontaneous closure rate if atrial septal defect diameter <8 mm
- if remains patent, CHF and pulmonary HTN can develop in adult life
Describe clinical features Atrial Septal Defect (3)
- history: often asymptomatic in childhood
- physical exam: grade 2-3/6 pulmonic outflow murmur, widely split, and fixed S2
- children with large atrial septal defects may have signs of heart failure (tachypnea, FTT, hepatomegaly, pulmonary rales/retractions)
Describe investigations: Atrial Septal Defect (3)
- ECG: RAD, mild RVH, RBBB (normal ECG does not rule out)
- CXR: increased pulmonary vasculature, cardiac enlargement (normal ECG does not rule out)
- Echo: diagnostic
Describe management: Atrial Septal Defect (2)
- elective surgical or catheter closure between 2-5 yr of age, though majority require no surgery
- size <8 mm will likely spontaneously close
Name most common congenital heart defect
Ventricular Septal Defect (30-50%)
Describe: Small Ventricular Septal Defect (4)
- majority
- clinical feature
- history: asymptomatic, normal growth, and development
- physical exam: early systolic to holosystolic murmur, best heard at LLSB, thrill
- investigations: Echo to confirm diagnosis (ECG and CXR are normal)
- management: most close spontaneously
Describe: Large Ventricular Septal Defect (4)
- epidemiology: CHF by 2 mo; late secondary pulmonary HTN if left untreated
-
clinical feature
- history: delayed growth, decreased exercise tolerance, recurrent URTIs or “asthma” episodes
- physical exam: holosystolic murmur at LLSB, mid-diastolic rumble at apex, size of VSD is inversely related to intensity of murmur, loss of splitting of second heart sound and a loud P2 suggests pulmonary hypertension
-
investigations
- ECG: LVH, LAH, RVH (normal ECG does not rule out)
- CXR: increased pulmonary vasculature, cardiomegaly, CHF (normal CXR does not rule out)
- Echo: diagnostic
- management: treatment of CHF and surgical closure by 1 yr old, if surgery required
True or false
Moderate-to-Large VSD Size of VSD is inversely related to intensity of murmur
True
Describe: Patent Ductus Arteriosus (1)
- patent vessel between descending aorta and left pulmonary artery (normally, functional closure within first 15 h of life, anatomical closure within first days of life)
Describe epidemiology: Patent Ductus Arteriosus (2)
- 5-10% of all congenital heart defects
- delayed closure of ductus is common in premature infants (1/3 of infants <1750 g); this is different from PDA in term infants
Describe natural history: Patent Ductus Arteriosus (1)
- spontaneous closure common in premature infants, less common in term infants
Describe clinical features: Patent Ductus Arteriosus (2)
- history: asymptomatic, or have apneic or bradycardic spells, poor feeding, accessory muscle use, CHF
- physical exam: tachycardia, bounding pulses, hyperactive precordium, wide pulse pressure, continuous “machinery” murmur best heard at left infraclavicular area
Describe investigations: Patent Ductus Arteriosus (3)
- ECG: may show left atrial enlargement, LVH, RVH
- ECHO is diagnostic
- CXR: may show normal to mildly enlarged heart, increased pulmonary vasculature, prominent pulmonary artery
Describe management: Patent Ductus Arteriosus (2)
- indomethacin (Indocid®): antagonizes prostaglandin E2, which maintains ductus arteriosus patency; only effective in premature infants
- catheter or surgical closure if PDA causes respiratory compromise, FTT, or persists beyond 3rd mo of life
Define: Coarctation of the Aorta (1)
- narrowing of aorta (almost always at the level of the ductus arteriosus)
Describe epidemiology: Coarctation of the Aorta (1)
- commonly associated with bicuspid aortic valve (50%); Turner syndrome (35%)
Describe clinical features: Coarctation of the Aorta (5)
- history: often asymptomatic
- physical exam
- blood pressure discrepancy between upper and lower extremities (increased suspicion/severity if >20 mmHg difference)
- diminished or delayed femoral pulses relative to brachial (i.e. brachial-femoral delay)
- possible systolic murmur with late peak at apex, left axilla, and left back
- if severe, presents with shock in the neonatal period when the ductus arteriosis closes
Describe prognosis: Coarctation of the Aorta (1)
- can be complicated by HTN; if associated with other lesions (e.g. patent ductus arteriosus, ventricular septal defect) can lead to CHF
Describe management: Coarctation of the Aorta (2)
- give prostaglandins to keep ductus arteriosus patent for stabilization and perform surgical correction in neonates
- for older infants and children balloon arterioplasty may be an alternative to surgical correction
Name 4 types: Aortic Stenosis
- valvular (75%)
- subvalvular (20%)
- supravalvular
- idiopathic hypertrophic subaortic stenosis (5%)
Describe: Aortic Stenosis
- clinical feature
- investigations
- management
-
clinical feature
- history: often asymptomatic, but may be associated with CHF, exertional chest pain, syncope, or sudden death
- physical exam: SEM at RUSB with aortic ejection click at the apex (only for valvular stenosis)
- investigations: echo for diagnosis
- management: valvular stenosis is usually treated with balloon valvuloplasty, patients with subvalvular or supravalvular stenosis require surgical repair, exercise restriction required