RCCS flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Fetal umbilical vein saturation

The umbilical vein carries the most oxygenated fetal blood, with saturation near 80% and PO2 about 30–35 mm Hg.

Ductus arteriosus closure timing

Functional closure of the ductus arteriosus usually occurs within 24–72 hours after birth; anatomic closure follows in about 2–3 weeks.

Foramen ovale fetal shunt

The foramen ovale allows right-to-left atrial flow in utero because right atrial pressure exceeds left atrial pressure and pulmonary vascular resistance is high.

Newborn ventricular dominance

At birth the right ventricle is relatively dominant; left ventricular mass exceeds right ventricular mass by approximately 6 months of age.

Fetal heart rate normal range

Normal fetal heart rate is approximately 110–160 beats per minute; rates persistently below 100 or above 180 require further evaluation.

Cardiac output Fick principle

Cardiac output equals oxygen consumption divided by the arteriovenous oxygen content difference; indexed cardiac index divides output by body surface area.

Fetal great vessel crossing

In the normal fetus the pulmonary artery lies anterior and leftward to the aorta, and the ductal and aortic arches show characteristic hockey-stick and candy-cane shapes.

Tetralogy of Fallot components

Tetralogy of Fallot consists of ventricular septal defect, overriding aorta, right ventricular outflow tract obstruction, and right ventricular hypertrophy; degree of obstruction determines cyanosis.

Transposition great arteries physiology

In D-transposition, the aorta arises from the right ventricle and pulmonary artery from the left ventricle, creating parallel circulations that require mixing through an atrial septal defect, ventricular septal defect, or ductus arteriosus.

Hypoplastic left heart syndrome

Hypoplastic left heart syndrome includes underdevelopment of left-sided structures with systemic output dependent on the ductus arteriosus and obligatory atrial-level mixing.

Ductal-dependent systemic circulation

Lesions such as hypoplastic left heart, critical aortic stenosis, interrupted aortic arch, and severe coarctation require prostaglandin E1 to maintain systemic blood flow after ductal closure.

Eisenmenger syndrome

Long-standing left-to-right shunt causes pulmonary vascular disease and rising pulmonary vascular resistance, eventually reversing the shunt to right-to-left with cyanosis.

Qp/Qs shunt calculation

The pulmonary-to-systemic flow ratio compares pulmonary and systemic blood flow, commonly estimated from oxygen saturations; values above 1.5 suggest a significant left-to-right shunt.

Cyanotic decreased pulmonary flow

Tetralogy of Fallot, pulmonary atresia, and tricuspid atresia typically cause cyanosis with decreased pulmonary blood flow and may be ductal dependent.

Cyanotic increased pulmonary flow

Transposition of the great arteries, total anomalous pulmonary venous return, truncus arteriosus, and single ventricle without pulmonary stenosis cause cyanosis with increased pulmonary blood flow.

Ultrasound frequency tradeoff

Higher-frequency transducers improve spatial resolution but reduce penetration; choose the highest frequency that provides adequate depth for the structure being imaged.

Nyquist limit and aliasing

The Nyquist limit is half the pulse repetition frequency; Doppler velocities exceeding it alias, which can be corrected by adjusting scale, baseline, or transducer frequency.

Continuous versus pulsed Doppler

Continuous-wave Doppler measures high velocities without depth resolution, whereas pulsed-wave Doppler provides depth-specific sampling but is limited by the Nyquist limit.

Frame rate determinants

Frame rate equals pulse repetition frequency divided by the number of scan lines per frame; reducing depth, sector width, or line density increases frame rate.

Doppler angle correction

Doppler velocity is accurate when the beam is parallel to flow; an angle of 20 degrees or less keeps the cosine error under about 6%.

M-mode advantage

M-mode provides high temporal resolution along a single line, making it useful for timing valve motion and measuring chamber dimensions.

VSD gradient RV pressure

Peak ventricular septal defect velocity gives the systolic pressure difference by the simplified Bernoulli equation; right ventricular systolic pressure equals systolic blood pressure minus that gradient when no outflow obstruction exists.

Aortic stenosis gradient

Peak aortic stenosis gradient is estimated as four times the square of peak velocity; mean gradient and continuity-equation valve area provide additional severity assessment.

Tricuspid regurgitation jet

Right ventricular systolic pressure is estimated from the tricuspid regurgitation jet using four times the square of peak velocity plus right atrial pressure.

Vena contracta regurgitation

Vena contracta width on color Doppler reflects the narrowest regurgitant jet; larger widths indicate more severe regurgitation, though pediatric thresholds differ from adult values.

Coarctation Doppler pattern

Coarctation shows increased systolic velocity with persistent diastolic forward flow and a sawtooth pattern; the peak gradient is estimated by the Bernoulli equation.

Fractional shortening formula

Fractional shortening equals end-diastolic dimension minus end-systolic dimension, divided by end-diastolic dimension, and reflects left ventricular systolic function.

Norwood stage I palliation

Norwood stage I reconstructs the aorta from the pulmonary artery, performs an atrial septectomy, and provides pulmonary blood flow by a modified Blalock-Taussig shunt or right ventricle-to-pulmonary artery conduit.

Bidirectional Glenn shunt

The bidirectional Glenn anastomoses the superior vena cava to the pulmonary arteries, typically at 3–6 months, reducing ventricular volume load and requiring acceptable pulmonary artery pressures.

Fontan circulation

The Fontan operation directs inferior vena cava blood to the pulmonary arteries without a ventricular pump; fenestration may preserve cardiac output at the cost of mild cyanosis.

Prostaglandin E1 adverse effects

Prostaglandin E1 can cause apnea, hypotension, fever, and irritability; airway monitoring and readiness for ventilatory support are required during infusion.

Endocarditis prophylaxis indication

Antibiotic prophylaxis before dental procedures is generally recommended for prosthetic heart valves, previous endocarditis, and certain unrepaired or palliated congenital heart lesions.