Cyanotic defects Notes


Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Cyanotic defects essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Cyanotic defects:

Hypoplastic left heart syndrome

Truncus arteriosus

Tetralogy of Fallot

Total anomalous pulmonary venous return

Transposition of the great vessels

NOTES NOTES CYANOTIC DEFECTS GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Heart defects with cyanotic presentation: blue discoloration of skin/mucous membranes, typically seen at fingertips, lips, extremities ▪ Develop in utero ▪ Persistent truncus arteriosus, hypoplastic left heart syndrome, transposition of great vessels can lead to heart failure ▪ Persistent truncus arteriosus, tetralogy of Fallot can lead to Eisenmenger syndrome SIGNS & SYMPTOMS ▪ Cyanosis ▪ See individual disorders DIAGNOSIS DIAGNOSTIC IMAGING ▪ Prenatal ultrasound ▪ Echocardiography ▪ Chest X-ray OTHER DIAGNOSTICS ▪ ECG TREATMENT MEDICATIONS ▪ See individual disorders SURGERY ▪ Definitive treatment OTHER INTERVENTIONS ▪ Lifestyle changes Figure 8.1 Illustration depicting blood flow in hypoplastic left heart syndrome. OSMOSIS.ORG 43
HYPOPLASTIC LEFT HEART SYNDROME PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ Congenital underdevelopment of left heart ▪ Respiratory distress, poor feeding/failure to thrive, left-sided heart failure CAUSES ▪ Unknown: primary congenital heart defect may reduce flow through left ventricle/ left outflow tract, affect other heart malformations ▪ Underdeveloped left ventricle, ascending aorta ▫ Aortic/mitral valves may also be affected, narrow, or absent (atresia) ▪ If untreated: left-sided heart failure → cardiogenic shock → death Atrial septal defect (ASD) and Patent ductus arteriosus (PDA) ▪ ASD/PDA required for post-natal survival in hypoplastic left heart syndrome ▪ With ASD, PDA: right heart function present but impaired; sometimes asymptomatic at birth ▫ Oxygenated blood in left atrium flows into right atrium through ASD → pulmonary artery → PDA → aorta → body ▫ Within one day: ductus arteriosus begins closing → cyanosis ▪ Without ASD, PDA: heart not capable of sustaining life outside womb ▫ Right heart functions normally → oxygenated blood enters left atrium → flow backs up due to small mitral valve, small left ventricle → high pressure in left atrium, blood circulated ineffectively by left ventricle 44 OSMOSIS.ORG DIAGNOSIS DIAGNOSTIC IMAGING Prenatal ultrasound Chest X-ray ▪ Cardiomegaly OTHER DIAGNOSTICS ECG ▪ Right ventricular hypertrophy ▪ After birth TREATMENT MEDICATIONS ▪ Prostaglandin E1 keeps ductus arteriosus open until surgery can be performed SURGERY ▪ Surgical repair/heart transplant based on complexity
Chapter 8 Cyanotic Defects PERSISTENT TRUNCUS ARTERIOSUS PATHOLOGY & CAUSES ▪ Truncus arteriosus fails to divide into aorta/ pulmonary artery ▪ Single giant artery branching off from right, left ventricles which splits into aorta, pulmonary artery ▪ Oxygenated, deoxygenated blood mix ▪ Deoxygenated blood mixes into systemic circulation → cyanosis CAUSES ▪ Associated with DiGeorge syndrome/22q11.2 deletion syndrome (abnormal tissue formation during development) ▪ Before birth, deoxygenated blood sent to mother, oxygenated blood arrives from mother ▫ Fetal heart sends blood through foramen ovale ▫ Oxygenated, deoxygenated blood mix in truncus arteriosus. Both circulations get same amount of oxygenated, deoxygenated blood ▫ Otherwise normal fetal development ▪ After birth, the baby relies on own lungs → foramen ovale closes ▫ Deoxygenated, oxygenated blood still mixed → cyanosis ▫ Excess blood shunted to pulmonary circuit, as pressure in pulmonary circuit is less than pressure of systemic circuit RISK FACTORS ▪ Combination of genes, maternal environment ▪ Smoking, excessive alcohol intake, teratogenic medications during pregnancy; gestational diabetes; viral illness during pregnancy (e.g. German measles); associated with genetic disorders (DiGeorge syndrome) COMPLICATIONS ▪ Cardiomegaly ▪ Pulmonary hypertension, can progress to permanent lung damage ▪ Respiratory problems ▪ Arrhythmia ▪ Valve regurgitation SIGNS & SYMPTOMS ▪ Difficulty breathing, pounding heart, weak pulse, poor feeding/failure to thrive, lethargy ▪ With physical exertion (severity varies) ▫ Dizziness, fatigue, palpitations, dyspnea ▪ Impaired growth ▪ Auscultation ▫ Loud systolic murmur along left sternal border due to increased flow through mitral valve ▫ Constant ejection click before S2 (closure of aortic, pulmonic valves) ▫ Diastolic flow murmur at apex when pulmonary blood flow increases DIAGNOSIS DIAGNOSTIC IMAGING X-ray ▪ Shows heart size, lung abnormalities, possible presence of excess fluid in lungs Echocardiogram ▪ Single large vessel arising from left, right ventricles ▪ Abnormalities of valves between large OSMOSIS.ORG 45
vessel and ventricle it arises from ▪ May show abnormal blood movement between right, left ventricle, and volume of blood flow to lungs OTHER DIAGNOSTICS ▪ Newborn pulse oximetry screening ▫ Low oxygen saturation ▫ Diagnose before symptoms develop ECG ▪ Atrial enlargement (notching of P waves/P mitrale) ▪ Ventricular hypertrophy ▪ Abnormal T waves ▪ Right axis deviation TREATMENT ▪ In rare cases, babies may survive into adulthood without surgical repair MEDICATIONS Diuretics ▪ Gets rid of excess fluid (e.g. chlorothiazide) Inotropic agents ▪ Strengthens cardiac contractions (e.g. Digoxin, treats congestive heart failure, slows down heart rate, increases force of contractions) Prophylaxis ▪ Antibiotics during dental/other surgical procedures to avoid infections SURGERY ▪ Goal: restore normal blood flow through heart ▪ Procedures vary depending on individual anatomy ▫ Close hole between right/left ventricles ▫ Separate large vessel into pulmonary artery, aorta ▫ Reconstruct single large vessel into new, complete aorta ▫ Implant new tube, valve to connect right ventricle with upper part of pulmonary artery, creating new, complete pulmonary artery OTHER INTERVENTIONS ▪ Lifestyle: possible limitation on intense physical activity ▪ Lifelong monitoring Figure 8.2 llustration depicting blood flow through the heart in persistent truncus arteriosus. 46 OSMOSIS.ORG
Chapter 8 Cyanotic Defects Figure 8.3 Gross pathology of a persistent truncus arteriosus. Both the left and right ventricles pump blood to both the aorta and pulmonary artery through a quadricuspid truncus valve. Figure 8.4 Gross pathology of a persistent truncus arteriosus. Both the left and right ventricles pump blood to both the aorta and pulmonary artery through a quadricuspid truncus valve. OSMOSIS.ORG 47
TETRALOGY OF FALLOT PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ Combination of four congenital heart abnormalities ▪ Right ventricular outflow tract stenosis (pulmonic stenosis): obstructs pulmonary circulation ▪ Right ventricular hypertrophy: compensates for right ventricular outflow tract stenosis ▪ Ventricular septal defect (VSD): hole in wall between ventricles. High pressure in right ventricle → blood shunts from right to left → deoxygenated blood to body ▪ Aorta overrides ventricular septal defect: aorta in abnormal position. Variable presentations ▪ Depend upon severity of stenosis ▪ Less severe right ventricular outflow obstruction often asymptomatic ▪ Cyanosis around lips, fingernails (“blue baby syndrome” ) ▪ Poor feeding/failure to thrive ▪ Harsh holosystolic murmur at left upper sternal border → sounds like pulmonary stenosis ▫ Right ventricular heave ▪ Older infants, children ▫ Clubbed fingers, toes after a few months ▫ Exertional dyspnea ▫ Hypercyanotic episode (tet spell): on exertion, infant’s oxygen demands increase → sudden decrease in oxygen saturation → cyanosis CAUSES ▪ Arises during cardiovascular development ▪ Most common cause of cyanotic congenital heart defects ▪ Four abnormalities together cause ▫ Mixing oxygenated, deoxygenated blood ▫ Narrowed vessels/valves that increase cardiac workload ▪ Severity of stenosis affects blood flow, changing pressure differentials ▫ Mild stenosis: left-right shunt → oxygenated blood simply goes through pulmonary circulation again ▫ Severe stenosis: right-left shunt → deoxygenated blood enters body circulation → less oxygen to tissues ▪ Leads to pulmonic regurgitation: blood flows backwards into RV, right heart overloads, can cause right-sided heart failure ▪ Associated with alcohol exposure in utero, maternal age 40+ years, poor nutrition or viral illness during pregnancy (e.g. rubella), Down syndrome or DiGeorge syndrome, positive family history of tetralogy of Fallot 48 OSMOSIS.ORG DIAGNOSIS DIAGNOSTIC IMAGING Echocardiography ▪ Pre/postnatal Chest X-ray ▪ “Boot-shaped” heart MNEMONIC: PROVe Components of tetralogy of Fallot Pulmonary infundibular stenosis Right ventricle hypertrophy Overriding aorta Ventricular septal defect
Chapter 8 Cyanotic Defects OTHER DIAGNOSTICS ECG ▪ Right ventricular hypertrophy, right atrial enlargement TREATMENT MEDICATIONS Prostaglandin E1 analogs (alprostadil) ▪ Severe cases ▪ Keep ductus arteriosus open → improve cyanosis until surgery Figure 8.5 Digital clubbing in an adult with tetralogy of Fallot. OTHER INTERVENTIONS ▪ Treat tet spell ▫ Infants squat to reduce cyanosis: kinks femoral arteries → increases vascular resistance → increases systemic pressure → increases pressure in left ventricle to greater than pressure in right ventricle → reverse shunt to leftright → resolve cyanosis SURGERY ▪ Cardiac repair surgery (first year of life) ▫ VSD patch closure (only oxygenated blood flows from left ventricle into aorta) ▫ Right ventricular outflow tract enlarged Figure 8.6 A chest radiograph of an infant demonstrating the classic boot-shaped heart seen in tetralogy of Fallot. Figure 8.7 Illustration depicting blood flow through a heart with Tetralogy of Fallot. OSMOSIS.ORG 49
TOTAL ANOMALOUS PULMONARY VENOUS RETURN PATHOLOGY & CAUSES ▪ Congenital heart defect characterized by anomalous connection of the pulmonary veins and the heart ▪ Occurs during first eight weeks of fetal development; cause unknown TYPES Supracardiac variant ▪ Most common ▪ Pulmonary veins open into brachiocephalic veins/superior vena cava (SVC) Cardiac variant ▪ Pulmonary veins open into coronary sinus/ right atrium Infradiaphragmatic variant ▪ Pulmonary veins open into portal/hepatic veins Mixed variant ▪ Oxygenated blood travels through pulmonary veins to right atrium/veins → blood does not leave pulmonary circulation → no systemic circulation ▪ Incompatible with life unless foramen ovale/patent ductus arteriosus present → oxygenated and deoxygenated blood mix → established connection between pulmonary and systemic circulation ▪ Anomalous connections often accompanied by pulmonary vein obstruction → pulmonary venous hypertension, severe cyanosis COMPLICATIONS ▪ Recurrent pulmonary vein stenosis 50 OSMOSIS.ORG SIGNS & SYMPTOMS ▪ Severity of symptoms depend upon presence/degree of obstruction ▪ Cyanosis, tachypnea, tachycardia, dyspnea, failure to thrive, recurrent respiratory infections ▪ In case of infradiaphragmatic variant: liver enlargement DIAGNOSIS DIAGNOSTIC IMAGING Chest X-ray ▫ Snowman sign (figure of 8): dilated SVC, pulmonary vein, brachiocephalic artery formshead; dilated right atrium forms snowman’s body Echocardiography ▪ Right ventricular and pulmonary artery volume loading ▪ Might show left atrium with no connecting veins LAB RESULTS ▪ Assess oxygenation and acid-base status: decreased values OTHER DIAGNOSTICS ECG ▪ Right ventricular hypertrophy Auscultation ▪ Systolic ejection murmur ▪ Increased pulmonary component of S2 ▪ Split S2 ▪ S3 gallop
Chapter 8 Cyanotic Defects TREATMENT SURGERY ▪ Surgery to establish blood flow from the right atrium to left atrium ▫ If present, pulmonary venous obstruction must be identified and treated promptly OTHER INTERVENTIONS ▪ Cardiac catheterization TRANSPOSITION OF THE GREAT VESSELS (TGA) PATHOLOGY & CAUSES ▪ Abnormal development causes aorta to arise from right ventricle, pulmonary artery to arise from left ventricle ▪ Transposition creates two small circuits of blood flow rather than one large ▫ Right side: right ventricle → aorta → body → right atrium → right ventricle (blood never oxygenated) ▫ Left side: left ventricle → pulmonary artery → lungs → pulmonary veins → left atrium → left ventricle (blood never deoxygenated) ▪ After birth → lungs used for oxygen → foramen ovale, ductus arteriosus close → no exchange between two circuits → cyanosis, death ▪ Sometimes, foramen ovale or ductus arteriosus stay open, or baby has ventricular septal defect (VSD); allows blood to circulate ▪ Different levels of severity of transposition of the great arteries (TGA) ▫ d-TGA: dextro-TGA/complete TGA (dextro = aorta on right) ▫ l-TGA: levo-TGA/congenitally corrected TGA (levo = aorta on left). Ventricles, valves switched. Great vessels in normal orientation, but connected to wrong ventricle. Normal blood flow circuits preserved RISK FACTORS ▪ During pregnancy: diabetes, rubella, poor nutrition, consumption of alcohol, > 40 years old SIGNS & SYMPTOMS ▪ In utero: asymptomatic ▪ d-TGA: ▫ Cyanosis, unchanged with supplemental oxygen (less severe if VSD present) ▫ Tachypnea ▫ Acidosis ▪ l-TGA: ▫ Asymptomatic DIAGNOSIS DIAGNOSTIC IMAGING Echocardiogram ▪ Evaluate heart function, structure Chest X-ray ▪ Classic triad ▫ Heart appears as egg on its side/“egg on a string” appearance ▫ Lung congestion ▫ Cardiomegaly Angiogram ▪ Pre-surgery OSMOSIS.ORG 51
TREATMENT MEDICATIONS ▪ Prostaglandin E: short-term solution. Keeps ductus arteriosus open SURGERY ▪ Balloon atrial septostomy: short-term solution. Hole created in atrial septum ▪ Surgically switch great vessels ▫ Five year survival rate > 80% ▫ No treatment: one year survival rate 10% Figure 8.8 Chest radiograph in both a lateral (L) and frontal (R) view, demonstrating the “egg on a string” sign of transposition of the great vessels. 52 OSMOSIS.ORG
Chapter 8 Cyanotic Defects Figure 8.9 Illustration depicting blood flow through a heart with dextro transposition of the great arteries. Figure 8.10 Illustration depicting blood flow through a heart with levo transposition of the great arteries. OSMOSIS.ORG 53

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