Unit 3 Pathophysiology - Chapter 34 Alterations of Cardiovascular Function in Children Flashcards
How does heart develop?
- Starts from mesenchyme (stem cell)
- begins as an enlarged blood vessel w/ large lumen + muscular wall
- bulges then twists then ends come together and fuse
- By 7th week, all structures of fetal heart and vascular system are present
What is important in closing atrial spetum and dividing AV canals into right/left AV orifices + closing septum
Endocardial cushions
The endocardial cushions are two thicker areas that develop into the walls (septum) that divide the four chambers of the heart. They also form the mitral and tricuspid valves. These are the valves that separate the atria (top collecting chambers) from the ventricles (bottom pumping chambers).
In fetus, pulomonary + systemic circulatory systems are connected by?
- Foramen ovale, opening between the atria (rt to left atrium)
- ductus arterosus (connection between aortic trunk and pulmonary artery (artery that leaves from rt ventricle to lung)
- allowing for mixed oxygenated blood
Fetal circulation order?
- Blood arrives via umbillical vein
- Ductus venosus (shunt that allows oxygentated blood in umbillical vein to bypass liver)
- Inferior vena cava [oxygenated blood]
- rt atrium [mixed oxygenated] => foramen ovale => **left atrium **+ left ventricle => aorta
- Other pathway [mixed oxygenated] (**rt ventricle **=> pulmonary trunk => ductus arteriosis => aorta)
- Systemic circulation
- Umbillical arteries
- Placenta (restart)
Is myocardial thickness the same in rt and left heart in fetal state?
Yes because pulmonary ciruclation is higher than resistance in systemic circulation
After birth what happens to vascular resistance
Systemic vascular resistance (SVR) increases and pulmonary vascular resistance (decreases)
PVR drops d/t lungs expanding and pulmonary vessels dilating after birth; continues to gradually decrease during first 8 weeks after birth ===> causes right myocardium to become thinner!
What happens at birth when the umbilicord is severed removing the low resistance placenta from systemic circulation?
SVR (systemic vascular resistance) increases causing left myocardium to become dominant and thicken overtime!
What structures change when resistance changes occur after birth?
- Foramen ovalve closes functionally at birth (anatomically several months later) — 6 months to yr
- ductus arteriosus closes 12-24 hrs after birth functionally (2-3 wks anatomically)
- ductus venous closes within 1 week after birth
How does the shift of gas exchange change?
From placenta to lungs
Most congenital cardiovascular defects occur by?
Develop by 4th week of gestation d/t environmental and genetic
Environmental risk factors associated with CHD?
Typically maternal conditions
* viral
* diabetes
* drug intake
* alcohol intake
* metabolic disorders
* advanced maternal age
Trisomy 21 or down syndrome
caused by extra chromosome w/ 3 at position 21
* eyes slant upward, small ears fold over top, larger tounge w/ small mouth, short neck, small hands w/ short fingers, 2 palm creases, short height, loose joints, flat nose
* heart defects, instestinal problems, vision/hearing problems, thyroid issues, leukemia?, learning problems
- atrioventricular septal defect (AVSD)
- atrial septal defect
trisomy 13 (patau syndrome)
additonal copy of chromosome 13
* brain or spinal cord abnormalities
* micropthalmia (poorly developed eyes)
* extra fingers or toes
* cleft lip (opening in lip)
* cleft palate (opening in roof of the mouth)
* hypotonia (weak muscle tone)
* intellectual disability
* may infants w/ trisomy 13 die within their first days or weeks of life (only 5-10% survive after 1st year)
* Ventricular septal defect (VSD)
* Patent ductus arteriosus (PDA) — connection between aorta and pulmonary artery remains open (small one less symptoms, large one can l/t heart failure, HTN in lung arteries, infection of inner lining of heart)
* dextrocardia — heart points toward right side, instead of left (mirror of regular heart, usually no symptoms // some cases it can be dextrocardia w/ situs inversus (organs mirrored too — no sx)
trisomy 18 (edward’s syndrome)
3 copes of 18 chromosome, happens at conception
- low birth weight
- intrauterine growth retardation — slow growth
- small, abnormally shaped head
- small jaw + mouth
- clenched fist with overlapping fingers
- many die before birth or within their first month; 5-10% children live past their 1st year w/ severe intellectual disability
- Ventricular septal defect (VSD)
- Patent ductus arteriosus (PDA) — connection between aorta and pulmonary artery remains open (small one less symptoms, large one can l/t heart failure, HTN in lung arteries, infection of inner lining of heart)
- Pulmonary stenosis — narrowing of pulmonary valve
cri du chat syndrome (5p)
piece of chromosome 5 missing
* high-pitched cry that sounds like a cat
* intellectual disability and delayed development
* microcephaly (small head size)
* low birth weight + hyptonia (weak muscle tone)
* hypertelorism (widely set eyes)
* low-set ears
* small jaw, rounded face
* Ventricular septal defect (VSD)
* Patent ductus arteriosus (PDA)— connection between aorta and pulmonary artery remains open (small one less symptoms, large one can l/t heart failure, HTN in lung arteries, infection of inner lining of heart)
* Atrial septal defect (ASD)
Turner syndrome (XO)
When one of the X chromosomes (sex chromosome) is missing or partially missing (female)
* short stature by 5
* ovarian hypofunction or premature ovarian failure
* oocytes die prematurely and ovarian tissue breaks down before birth
* infertile, only hormone therapy can initiate puberty
* small % retain normal ovarian function through young adulthood
* webbed neck (extra folds), low hairline back of neck, lymphedema - puffiness of hands and feet, kidney/skeletal problems
* most have normal intelligence (some delays, learning disabilities, or BH problems)
* Coarctation of the aorta (COA) —– narrowing of aorta at one point [aortic arch] (brain aneurysm, hemorrhage, dissection [rupture], aneurysm in aorta wall, CAD, stroke)
* Aortic stenosis (AS) —- narrowing of aortic valve causing left ventricle to pump harder through it
Klinefelter variant (XXXXY)
- boys and men
- taller than average; infertile
- small testes w/ primary testicular insufficiency
- l/t incomplete puberty, gynecomastia, decreased muscle mass, decreased bone denisty, less body hair
- cryptochidism (undescended testes)
- hypospadias (opening of urethra on underside of penis)
- micropenis
- radioulnar synostosis – abnormal fusion of forearm bones
- clindoactyly (curved pinky)
- pes planus (flat feet)
- hypotonia (low muscle tone)
- learning disabilities, delays in speech + language + reading
- difficulty expressing themselves => better receptive language skills
- ADHD, emotional immaturity, 10% w/ autism spectrum disorder
- at risk for metabolic syndrome (type 2 DM, HTN, belly fay, lipids)
- tremors, breast cancer, systemic lupus erthematosus and rheumatoid arthritis
- Patent ductus arteriosus — connection between aorta and pulmonary artery remains open (small one less symptoms, large one can l/t heart failure, HTN in lung arteries, infection of inner lining of heart)
- Arterial septal defect
Acyanotic CHDs
increase pulmonary blood flow consist of abnormal openings
* PDA, ASD, VSD
* AVD or atrioventricular canal defect (can be partial involving only two upper chambers or ocmplete involving all four chambers)
* truncus arteriosus OR common arterial trunk — aorta and pulmonary artery does not separate (one large blood vessel means oxygen-poor and oxygen-rich blood mix) which increaes amount of blood flowing into lungs; heart adjusts to work harder [usually have a ventricular septal defect w/ aorta and pulmonary artery combined but both exit separately to pulmonary and systemic]
* FOR TRUNCUS ARTERIOSUS ==> needs surgery, generally successful if done before baby is 1 month old
These conditions permit blood to shut from left (systemic circulation) to right (pulmonary circulation)
Left-to-right shunt does not interfere with flow of circulating oxygenated blood through system
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Cyanotic congenital heart disease: Cyanotic heart disease involves heart defects that reduce the amount of oxygen delivered to the rest of the body. Acyanotic congenital heart disease: With this type of heart defect, blood contains enough oxygen, but it’s pumped throughout the body abnormally.
Cynanosis
Bluish discoloration of skin (not enough O2 to tissues)
1. reduced pulmonary blood flow
2. overloaded pulmonary circulation causing pulmonary HTN/edema or respiratory difficulty
3. large amounts of unoxygenated blood to shunt from pulmonary to systemic circulation
Abnormal connection between left and right circuit is large?
Volume and pressure overload in pulmonary circulation => Heart failure
Truncus arteriosus fails to divide longitudinaly into aorta and PA
All mixed blood enters the truncus l/t dual circulatory system delivery causing varying degrees of cyanosis and HF
Which conditions that cause decreased pulmonary blood flow? What are the consequences?
Teratology of fallot or critical congenital heart defect
1. ventricular septal defect
2. Narrowing of pulmonary valve and main pulmonary artery
3. aortic valve enlarged opening to both ventricles rather than just left, sitting right on top of the ventricular septal defect
4. muscualr wall of lower right chamber (rt ventricle) is thicker [ventricular hypertrophy]
Tricuspid atresia
* the valve that controls blood flow from rt upper chamber of heart to the right lower chamber of the heart doesn’t form at all (tricuspid is seal tissue)
* needs an atrial septal defect and ventricular septal defect to have blood exit right side into left atrium + ventricle
* since rt ventricle is sealed off, it not used, weakened, and underdeveloped; therefore left ventricle pushes mix blood into aorta and pulmonary artery => causing cyanosis
Flow to lungs decreases and cyanosis occurs
Obstruction of ventricular outflow commonly caused by?
- Pulmonary stenosis — narrowing of pulmonary valve
- Aortic stenosis — narrowing of aortic valve causing left ventricle to pump harder through it
- Coarctation of the aorta (COA) —– narrowing of aorta at one point [aortic arch] (brain aneurysm, hemorrhage, dissection [rupture], aneurysm in aorta wall, CAD, stroke)
- Interrupted aortic arch —-
* All IAA babies have an VSD or even ASD or truncus arteriosus
* In this case, aorta doesn’t develop correctly and is divided, such as only part of aorta functions correcty due while other sole aorta is joined to the pulmonary artery
Normally, it’s shaped like an arch or curve. In an interrupted aortic arch, part of the aorta is missing, leaving a gap.
* DiGeorge Syndrome chromosome 22
Despite ventricular obstruction, how does body compensate?
Ventricular output remains normal for long time d/t compensatory ventricular hypertrophy stimulated by afterload
* For postductal (adult) COA, collateral circulation develops around coarctation (alternate blood vessels in body takover when artery or vein becomes blocked or damaged)
