Pathophysiology of congenital heart disease
Chronic compensated HF
Chronic compensated HF: heart failure that is clinically compensated; the patient is asymptomatic or symptomatic and stable, with echocardiographic signs of HF
ductus arteriosus
the vessel that connects the pulmonary artery to the descending aorta during fetal life
Four anomalies that characterize tetralogy of fallot (TOF)
-4 anomalies arise that characterize this condition: ●VSD caused by anterior malalignment of the interventricular septum ●Subvalvular pulmonic stenosis b/c of obstruction from the displaced infundibular septum ●An overriding aorta that receives blood from both ventricles ●RV hypertrophy owing to the high pressure load placed on the RV due to pulmonic stenosis
Endothelin Receptor Antagonists
-Act as vasodilators -Main therapeutic use for treatment of pulmonary artery HTN (PAH) ●PAH associated with activation of ET- 1 system -Ex: ●Bosentan: Antagonizes both ETA and ETB ●Macitentan: Antagonizes both ETA and ETB ●Ambrisentan: Selectively inhibits ETA receptor -Reduce pulmonary vascular resistance and pulmonary artery Pressure -Improves dyspnea and expertional capacity -Side effects: ●Generally well tolerated ●Reversible elevation in hepatic transaminases ●Peripheral edema ●teratogenic!!
Treatment of VSD
-By age 2, 50% of small and moderate VSDs undergo sufficient spontaneous closure to make intervention unnecessary -Surgical correction of the defect is recommended in the first few months of life if heart failure/pulmonary vascular HTN is indicated -Moderate- sized defects w/o pHTN but with significant L to R shunting can be corrected later in childhood -Some patients can undergo less invasive catheterization
Association of coarctation with monosomy X (turner syndrome)
-Cardiovascular abnormalities are the most common cause of death in childhood for children with Turner syndrome
Diagnosis of ASD w/chest radiograph
-Chest radiograph: -Heart enlarged due to right atria and right ventricular dilation -pulmonary artery prominent with increased pulmonary vascular markings
symptoms of patent ductus arteriosus
-Children with small PDAs: asymptomatic -Large L to R shunts: -develop early CHF with tachycardia, poor feeding, slow growth, and recurrent lower respiratory tract infections -Moderate- sized lesions: -Fatigue, Dyspnea, and palpitations in adolescence and adult life -Afib can occur due to LA dilation -Turbulent blood flow defect can set the stage for endarteritis (endovascular infection)
Diagnosis of ASD w/ECG
-ECG: -shows right ventricular hypertrophy, often w/R. atrial enlargement and incomplete or complete R.BBB -in pts. with ostium primum: left axis deviation (LAD) is common and is thought to be a result of displacement and hypoplasia of left bundle branch's anterior fascicle
Transposition of the Great Arteries
-Each great vessel arises from the opposite ventricle ●Aorta: RV ●Pulmonary artery: LV -7% of congenital heart defects (40 per 100,000 live births) -Most common cause of cyanosis in the neonatal period -Precise cause is unknown, but one theory contends that failure of the aorticopulmonary septum to spiral in a normal fashion during fetal heart development -The process of infundibular reabsorption may be reversed
Diagnosis of ASD w/Echcardiography
-Echo: -Right atrial and ventricular enlargement -may see transatrial shunt on color doppler flow assessment
Eisenmenger syndrome
-Eisenmenger's syndrome is the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect (typically by a ventricular septal defect, atrial septal defect, or less commonly, patent ductus arteriosus) causes pulmonary hypertension and eventual reversal of the shunt into a cyanotic right-to-left shunt. -B/c of the advent of fetal screening with echo early in life, the incidence of heart defects progressing to Eisenmenger's has decreased.
PE findings in pts. with coarctation of the aorta
-Femoral pulses are weak and delayed -Elevated BP in upper body is most common finding -If coarctation occurs distal to the take off point of the L subclavian artery, the systolic pressure in the arm will be greater than in the legs -15- 20 mmHg BP higher in R arm compared to leg is sufficient to suspect coarctation -If coarctation occurs proximal to the takeoff point of the L subclavian artery, the systolic pressure in the R arm may exceed the pressure in the L arm -A turbulent murmur may be heard over the chest and/ or back -A prominent tortuous collateral arterial circulation may create continuous murmurs over the chest in adults
Heart failure
-Heart failure: results from when the heart is unable to pump blood forward at a sufficient rate to meet the metabolic demands of the body or is able to do so only if cardiac pressures are abnormally high -Clinical symptoms of heart failure: ●Fatigue ●Shortness of breath ●Volume overload -Most commonly results from the conditions of impaired LV functioning
Diagnostic studies for patent ductous arteriosus w/cardiac catheterization
-Increased O2 saturation in pulmonary artery compared to RV -Angiography shows abnormal blood flow through PDA
Diagnostic studies VSD w/cardiac cath
-Increased O2 saturation in the RV compared with RA -Result of shunting highly oxygenated blood from LV to RV
Diagnostic studies VSD w/ECG
-L atrial enlargment and L ventricular hypertrophy in those with a large shunt -R ventricular hypertrophy evident if pulmonary vascular disease has developed
Diagnosis of coarctation of the aorta w/ECG
-L ventricular hypertrophy resulting from pressure load put on chamber
Diagnostic studies for patent ductous arteriosus w/CXR
-LA and LV enlargement with prominent pulmonary vasculature markings -In adults, calcification of ductus can be seen
Diagnostic studies for patent ductous arteriosus w/ECG
-LA enlargement and LV hypertrophy when large shunt is present
PE findings in patent ductous arteriosus
-Most common finding in L to R shunt through PDA: continuous, machine-like murmur heard best in the subclavicular region -Murmur is present throughout cardiac cycle b/c a pressure gradient exists b/t the aorta and pulmonary artery in both systole and diastole -If pulmonary vascular disease develops, the gradient decreases = diminished flow through PDA and murmur becomes shorter -If Eisenmenger syndrome develops, lower extremity cyanosis and clubbing will be present
PE findings in VSD
-Most common finding is a harsh holosystolic murmur best heart at the L sternal boarder -Smallest defects= loudest murmurs bc of the great turbulence -Systolic thrill can commonly be palpated over the region of the murmur -A mid-diastolic murmur can be heard at the apex due to increased blood flow over mitral valve -If pulmonary vascular disease develops: -holosystolic murmur diminishes as the pressure gradient cross the defect decreases -RV heave, loud pulmonic closure sound (P2), and cyanosis becomes evident
symptoms of ASDs
-Most infants are asymptomatic -May be detected by presence of murmur on PE -25% undiagnosed until adulthood -Dyspnea on exertion, fatigue, and recurrent lower respiratory tract infection may be present -Adults: decreased stamina and palpitations due to atrial tachycardia resulting from RA enlargement
Diagnosis of coarctation of the aorta w/CXR
-Notching of the inferior surface of the posterior ribs due to enlargement of intercostal vessels supplying collateral circulation to descending aorta -May be able to see indention or aorta
fetal circulation
-Oxygenated blood comes from maternal circulation from the placenta via the umbilical vein -1/2 of the blood is shunted through the ductus venosus -the other half of blood is shunted through the portal vein to the liver and then into the IVC via the hepatic veins -Blood in the fetal IVC is a mixture of well oxygenated blood from umbilical venous blood and low oxygenated tension returning from the systemic veins of the fetus -Most IVC blood entering the RA is directed to the LA via the foramen ovale -In the RA, the shunted blood mixes with a small amt of poorly oxygenated blood returning to the LA through the fetal pulm v. -From the LA, blood flows into the LV and is pumped into the ascending aorta -Well-oxygenated blood is distributed preferentially to 3 areas: (9% enters coronary artery to perfuse myocardium; 62% travels to carotid and subclavian vessels to the upper body and brain; 29% passes through descending aorta to rest of fetal body) -The remaining well-oxygenated blood from the IVC mixes with low oxygenated blood from the SVC and enters the RV ("workhorse of the fetal heart") -From the descending aorta, blood distributed to the lower body and umbilical arteries leading back to placenta for gas exchange
Diagnosis of TOF w/CXR
-Prominence of RV and decreased size of main pulmonary artery segment -"boot shaped" heart
Diagnosis of TOF w/ECG
-RV hypertrophy with right axis deviation
Tetralogy of Fallot (TOF)
-Results from a single developmental defect: an abnormal anterior cephalad displacement of the infundibular (outflow tract) portion of the interventricular septum -most common cyanotic congenital cardiac disease occurring after infancy (5 in 10000 births) -often associated with cardiac defects (R sided aortic arch (25%), ASD (10%), less often L coronary a defect) -Microdeletion of chromosome 22 has been identified (22q11) in patients with the syndrome of tetralogy of fallot as one of the cardiovascular defects
VSD symptoms
-Small VSDs= asymptomatic -Infants with large VSD: early symptoms of heart failure (tachypnea, poor feeding, failure to thrive, frequent lower respiratory infections) -Patients with VSDs complicated by pulmonary vascular disease and reversed shunts present with dyspnea and cyanosis -Bacterial endocarditis can develop in both
Subaortic stenosis
-Subaortic stenosis is caused by a thickened ring or collar of dense endocardial fibrous tissue below the level of the cusps. -Subaortic stenosis is usually associated with a prominent systolic murmur and sometimes a thrill.
Left-sided heart failure (forward heart failure):
-There are two types of left-sided heart failure: -systolic failure: occurs when the contraction of the muscle wall of the left ventricle malfunctions, which compromises its pumping action. This causes a decrease in the ejection fraction below the normal range, and over time, enlargement of the ventricle. -Diastolic failure: occurs when the left ventricle muscle wall is unable to relax normally, because the muscle has become stiff. -When this happens, the heart does not fill properly, although the ejection fraction usually remains within the normal range, the stroke volume is reduced. -Regardless of the malfunction, left-sided heart failure leaves the heart unable to pump enough blood into the circulation to meet the body's demands, and increased pressure within the heart causes blood to backup in the pulmonary circulation, producing congestion in your lungs.
ventricular septal defects (VSD)
-abnormal opening in the interventricular septum -relatively common (1.5-3.5 per 1000 births) -most often located in the membranous (70%) and muscular (20%) portions of the septum -rare VSDs occur just below the aortic valve or adjacent to the AV valves
ostium secundum ASD
-atrial septal defect at the site of the foramen ovale -90% of cases of ASD -10-15% of all congenital heart defects -arises from inadequate formation of the septum secundum, excessive reabsorption of the septum primum, or a combination
Ostium primum ASD
-atrial septal defect in the inferior portion of the interatrial septum, adjacent to the AV valves -10% of cases of ASD -found in 25% of down syndrome cases -results from the failure of the septum primum to fuze with the endocardial cushions
Uncomplicated ASD
-blood is shunted from L to R atrium but is not reversed due to greater compliance of R ventricle compared to left ventricle -Volume overload can cause enlargement of RA and RV > compliance of RV diminishes > L to R shunt lessens -If severe pulmonary vascular disease develops (Eisenmenger syndrome), the direction of the flow can reverse resulting in R to L shunting and deoxygenated blood entering circulation > hypoxia and cyanosis
Diagnosis of ASD w/cardiac catheterization
-cardiac cath -rarely done to confirm ASD but may be used to assess pulmonary vascular resistance -O2 saturation in RA should be approximately the same as the SVC, but in ASD it is much higher
Aortic stenosis and atresia
-congenital narrowing and obstruction of the aortic valve -can occur at three locations (valvular, subvalvular, supravalvular) -congenital aortic stenosis is an isolated lesion in 80% of cases -In severe congenital aortic stenosis or atresia, obstruction of the left ventricular outflow tract leads to hypoplasia of the left ventricle and ascending aorta, sometimes accompanied by dense, porcelain-like left ventricular endocardial fibroelastosis. -The ductus must be open to allow blood flow to the aorta and coronary arteries, and the constellation of findings is called the hypoplastic left heart syndrome. -Pressure hypertrophy of the left ventricle develops as a consequence of the obstruction to blood flow, but congenital stenosis are well tolerated unless very severe. -Unless a palliative procedure is done to preserve PDA patency, duct closure in the first week of life is generally lethal -less severe congenital aortic stenosis can be compatible with long survival. -Although mild stenosis can often be managed conservatively with antibiotic prophylaxis (to prevent endocarditis) and avoidance of strenuous activity, the resulting left ventricular hypertrophy still carries a risk of sudden death with exertion.
Cyanosis in congenital defects
-discoloration of skin/mucous membranes caused by the presence of too much deoxy-hemoglobin (4g/dL= 80-85% S)2 in the neonate -in congenital defects, cyanosis results from defects that allow poorly oxygenated blood from the right side of the heart to be shunted to the left side (thereby bypassing the lungs)
Coarctation of the aorta (pre-ductal and post-ductal)
-discrete narrowing of the aortic lumen -1 in 6000 births -most commonly associated with cardiac abnormality of bicuspid aortic valve -also occurs in turner syndrome (XO) -preductal: infantile; postductal: adult type -due to location of narrowing in relation to the ductus arteriosis -not used anymore b/c most narrowing occurs next to the ductus (juxtaductal)
patent ductus arteriosus
-ductus arteriosus: the vessel that connects the pulmonary artery to the descending aorta during fetal life -PDA develops when the ductous fails to close after birth producing a persistent connection to the great vessels -1/2500-5000 births -risk factors: maternal rubella, prematurity, birth at high altitude
Endocardial cushion defects with trisomy 21
-endocardial cushion defect (ECD) or atrioventricular canal defect (AVCD) is an abnormal heart condition in which the walls separating all 4 chambers of the heart are poorly formed or absent -the valves separating the upper and lower chambers of the heart also have defects during formation -congenital heart disease seen in trisomy 21 -Endocardial cushions are two thicker areas that develop into the walls (septum) that divide the 4 chambers of the heart as well as the mitral and tricuspid valves -the most frequent type of congenital heart disease associated with trisomy 21 -70% of children with AVCD/ECD have trisomy 21 -usually complete and not associated with other cardiac anomalies
Treatment of ASD
-if the volume of blood shunted is hemodynamically significant, elective surgical repair can be done to prevent HF or chronic pulmonary vascular disease -directly suture closure or with pericardial or synthetic patch -percutaneous repair can be done with an IV cath
Pathophysiology of coarctation of the aorta
-increased afterload in the LV due to narrowing of the aorta -head and upper extremities are usually fine b/c the arteries branch proximal to where the narrowing occurs -areas supplied by the descending aorta (lower extremities) may be diminished -compensatory alterations: LV hypertrophy Dilation of collateral blood vessels from the intercostal artery that bypass the coarctation and provide blood to more distal descending aorta -can enlarge and erode the undersurface of the ribs
Diagnostic studies VSD w/chest radiography
-may be normal in patients with small defects -in pts. with large shunts cardiomegaly and prominent pulmonary artery with peripheral tapering may be evident
Pardoxical embolism with patent foramen ovale
-occurs when thrombus in systemic vein breaks off and travels to the RA, then passes through the PFO to the LA if heart pressure is transiently elevated (Cough/sneeze/valsalva) and then enter arterial circulation
patent foramen ovale
-persistence of normal fetal anatomy -present in 20% of the population -not considered a true ASD -foramen ovale normally closes w/in a few days after birth and is permanently sealed by 6 months (fusion of the atrial septa) -when fusion fails to occur a patent foramen ovale occurs -usually clinically silent (pressure is greater in the L atrium than right atrium causing the one way valve to be closed) -If Right atrial pressure becomes elevated (pHTN or R side HF) pathological right to left shunting can occur: causing deoxygenated blood to pass directly into arterial circulation
atrial septal defect (ASD)
-persistent opening of the interatrial septum after birth that allows direct communication b/t LA and RA -common (1 in 1500 births) -most common site foramen ovale (ostium secundum) -less common (ostium primum): inferior portion of ineratrial septum (adjacent to the AV valves)
Physical Exam Findings (patients with ASD)
-prominent systolic impulse may be palpated above the lower left sternal border (contraction on the dilated RV-RV heave) -S2 demonstrates a widened fixed splitting pattern (due to normal respiratory variation in systemic venous return being countered by reciprocal changes in the volume of blood shunted across the ASD) -increased volume of blood flowing across the pulmonic valve creates a systolic murmur at the upper left sternal border -murmur may also be present at the lower L sternal border due to increased blood flow across the tricuspid vale as well -no murmur will be heard across ASD itself since there is not a significant pressure gradient b/t atria
Sinus venosus defect
-similar to ASD but morphologically distinct -'unroofing' defect w/the absence of normal tissue b/t the Right pulmonary veins and right atrium -Technically NOT a defect with the atrial septum -Often large defects that results in flow from Right pulmonary veins and Left atrium into the Right atrium -pathophysiology similar to ASD
pathophysiology of patent ductous arteriosus
-sm. muscle of the ductus arteriosus usually constricts after birth due to a sudden rise in blood oxygen tension and reduction in the level of circulating prostaglandins -over the next few weeks intimal proliferation and fibrosis leads to permanent closure -failure to close = permanent shunt b/t descending aorta and pulmonary artery -extent of shunting depends on the size of ductus and on relative resistance b/t vasculature -prenatally: pulmonary vascular resistance is high as blood is diverted away from the immature lungs to the aorta -postnatally: pulmonary resistance drops and shunt reverses direction and blood flows from the aorta to the pulmonary circulation to flow instead -The L to R shunt caused by the PDA leads to LV dilation and L sided HF due to pulmonary circulation, LA and LV become volume overloaded -R heart remains normal unless pulmonary vascular disease ensues -Results in Eisenmenger syndrome causing shunt reversal = blood flows from the pulmonary artery, through the ductus, to the descending aorta -Results in deoxygenated blood flowing to lower extremities= blue feet -Upper extremities are not cyanotic bc they receive normally saturated blood from the aorta proximal to the ductus (ascending aorta)
Treatment of TOF
-surgical closure of VSD -enlargement of subpulmonary infundibulum via pericardial patch
Pathophysiology of VSD
-the hemodynamic change and magnitude of the shunt is dependent on the size of the defect and the relative resistance of the pulmonary and systemic vasculature -in small VSDs, the defect offers more resistance to flow than the pulmonary or systemic vasculature thereby preventing a significant left to right shunting -In large 'nonrestrictive' VSDs, the volume of the shunt is determined by the relative pulmonary and systemic resistances -in the prenatal period: the pulmonary and systemic resistance is approximately the same = no significant shunting -after birth: the pulmonary vascular resistance falls = increasing left to right shunting -when the defect is large the RV, LV, pulmonary circulation and LA experience a relative volume overload -initially increased return to the LV increases SV -over time progressive chamber dilation, systolic dysfunction and symptoms of HF can develop -can cause pulmonary vascular disease as early as 2 years old -may reverse to right-to-left shunt as pulmonary vascular resistance exceeds systematic
acyonotic lesions
-these lesions include: intracardiac or vascular stenosis, valvular regurgitation, and Left to Right shunting defects
Right-sided heart failure (backward heart failure)
-usually occurs as a result of left-sided heart failure. -When the left side of your heart fails, the pressure increases in the right side. -Over time, this damages and weakens the right side of your heart, which then also loses pumping power. -This causes blood to back up in circulatory system supplying the rest of your body causing fluid retention (edema) in your limbs (particularly your legs, ankles, and feet) within your abdomen, and around your liver.
symptoms of coarctation of the aorta
-usually present shortly after birth w/Sx of HF -infants may exhibit differential cyanosis if the ductus arteriosus fail to constrict as well (lower body appears cyanotic b/c of the R-to-L flow of deoxygenated blood from the pulmonary artery across the PDA and into the descending aorta beyond the coarctation) -less severe coarctation: mild weakness/pain in lower extremities after exercise (claudication) -small/asymptomatic coarctation may lead to upper extremity HTN later in life
Treatment for PDA
-w/o pulmonary vascular disease or cardiac abnormalities PDA should be therapeutically occluded -I.e. prostaglandin synthesis inhibitors (indomethacin) -Rarely spontaneous closures occur after birth -Surgical ligation or transcatheter occlusion device can also be done -Always closed due to high risk of endarteritis
Paradoxical embolism
-when a venous clot travels to the right heart chambers and is able to pass through an abnormal intracardiac communication, it then enters systemic circulation -a PFO is usually clinically silent b/c the one way valve, though not sealed remains functionally closed (b/c LA pressure is higher than in the RA) -PFO become significant if RA pressure becomes elevated (pHTN or right HF) > pathological R-to-L shunting -paradoxical embolism occurs when thrombus in a systemic vein breaks loose > travels to the RA > passes across the PFO to the LA (if Right heart pressure is elevated- at least transiently) > then to systemic arterial circulation
Acute decompensated HF
Acute decompensated HF: sudden deterioration of chronic HF or new onset of severe HF due to an acute cardiac condition (e.g., myocardial infarction)
Bosentan
Antagonizes both ETA and ETB endothelin receptors
Macitentan
Antagonizes both ETA and ETB endothelin receptors
Ambrisentan
Selectively inhibits ETA receptor
valvular aortic stenosis
With valvular aortic stenosis the cusps may be hypoplastic (small), dysplastic (thickened, nodular), or abnormal in number (usually acommissural or unicommissural).
Diagnostic studies for TGA
●Chest xray: Relatively normal ●ECG: RV hypertrophy ●Echo: Needed for definitive diagnosis
What are the two types of endocardial cushion defect?
●Complete ECD -This condition involves an atrial septal defect (ASD) and a ventricular septal defect (VSD). -People with a complete ECD have only one large heart valve (common AV valve) instead of two distinct valves (mitral and tricuspid). ●Partial (or incomplete) ECD -In this condition, only an ASD, or an ASD and VSD are present. -There are two distinct valves, but one of them (the mitral valve) is often abnormal with an opening ("cleft") in it. This defect can leak blood back through the valve
Symptoms of tetralogy of fallot
●Dyspnea on exertion -Exertion, feeding, crying when systemic vasodilation results in increased R-to-L shunt ●Manifestations: -Syncope -Convulsions -Irritability -Cyanosis -Hyperventilation ●Squatting down alleviates symptoms which is thought to increase systemic vascular resistance by "kinking" the femoral artery down= decreases R-to-L shunt and directing more blood from the RV to the lungs
Endothelin- 1 (ET-1)
●Endothelin- 1 (ET-1): vasoactive peptide that is synthesized and released by endothelial cells ●Binds 2 receptors: ETA and ETB (Both present on VSMCs) ●Binding results in vasoconstriction -ETB also found in endothelial cells ●Promotes vasodilation ●Cellular cascade: GPCR (Gq) → PLC → IP3 → Ca2+ release from intracellular stores → sm. muscle contraction → vasoconstriction ●Regulation: ETB in endothelial cells stimulation promotes vasodilation via release of NO ● In blood vessels, sm. muscle vasoconstriction by ET- 1 dominated over vasodilation in both systematic and pulmonary arteries
problems caused by endocardial cushion defect
●Increased blood flow to the lungs resulting in increased pressure in the lungs -In ECD, blood flows through the abnormal openings from the left to the right side of the heart, then to the lungs -More blood flow into the lungs makes the blood pressure in the lungs rise ●Heart failure -The extra effort needed to pump makes the heart work harder than normal. -The heart muscle may enlarge and weaken. -This can cause swelling in the baby, problems in breathing, and difficulty in feeding and growing. ●Cyanosis -As the BP increases in the lungs, blood starts to flow from the right side of the heart to the left. -The oxygen-poor blood mixes with the oxygen-rich blood.
pathophysiology of tetralogy of fallot
●Increased resistance by the subvalvular pulmonic stenosis causes deoxygenated blood returning from the systemic veins to be diverted from the RV through the VSD to the LV and into systemic circulation= hypoxia and cyanosis ●The severity of the shunt flow across the VSD is a result of the extent of the pulmonic stenosis but changes in pulmonary or systemic vascular resistance can affect it as well
PE findings in TGA
●Infants appear blue with generalized cyanosis that progresses as the ductus arteriosus closes ●Palpation of the chest reveals RV impulse at the lower sternal border as the RV faces systemic pressure ●Accentuated S2 due to ant placement of aortic valve
Treatment of TGA
●Initially: maintenance of ductus arteriosus via prostaglandin infusion and creation of intra-arterial communication via a balloon catheterization ●Surgical: arterial switch operation -Transection of the great vessels above the semilunar valves and origin of the coronary a. -Allows the great vessels to be reversed to correct position
Physical exam findings in tetralogy of fallot
●Mild cyanosis on the lips, mucous membranes, and digits ●Infants with severe pulmonic stenosis may have profound cyanosis in the first few days of life ●Severe hypoxia can lead to clubbing of fingers and toes ●RV hypertrophy may be appreciated as palpable heave along L sternal border ●A systolic ejection murmur can be heard at the upper L sternal border created by turbulent blood flow through the stenotic R ventricular outflow tract
Tx of coarctation of the aorta
●Neonates w/ severe obstruction: -Prostaglandin infusion administered to keep the ductus arteriosus patent= maintains blood flow to the descending aorta until surgery ●Children: -Surgery to prevent systemic HTN -Excision of the narrowed aortic segment with end- to- end reanastomosis or direct repair using a patch ●adults: -Transcatheter balloon dilation w/ or w/o stent
Theories of pathogenesis of coarctation of the aorta
●Reduced anterograde blood flow through the L side of the heart and ascending aorta during fetal life leads to hypoplastic development of the aorta -"No flow no go" ●Ectopic muscular ductus arteriosus tissue extends into the aorta during fetal life and constricts following birth at the same time the ductus closes ●Probably just one manifestation of diffuse aortic disease
Supravalvular aortic stenosis
●Supravalvular aortic stenosis is a congenital aortic dysplasia with thickening of ascending aortic wall and consequent luminal constriction. ●In some cases it is a component of a multiorgan developmental disorder resulting from deletions on chromosome 7 that include the gene for elastin. ●Other features of the syndrome include: -Hypercalcemia -cognitive abnormalities -characteristic facial anomalies (Williams-Beuren syndrome). ●Elastin gene mutations may cause supravalvular stenosis by disrupting elastin-smooth muscle cell interactions during aortic morphogenesis.
pathophysiology of transposition of the great arteries
●TGA separates the pulmonary and systemic circulations by placing the 2 circuits in parallel rather than in series -Forces desaturated blood from the systemic venous system to pass through the RV → return to systemic circulation through the aorta w/o undergoing normal oxygenation in the lungs -Oxygenated pulmonary venous return → LV → back through the pulmonary artery → to the lungs w/o giving oxygen to systemic circulation -Result: extremely cyanotic/ hypoxic neonate ●TGA is lethal without intervention ●Compatible with life in utero due to the flow through the ductus arteriosus and the foramen ovale -Fetal blood flow: Oxygenated fetal blood flows from the placenta → RA via the umbilical veins → LA via the foramen ovale → LV → pulm a. → aorta via the ductus arteriosus ●Maintaining these openings in TGA allows communication b/t parallel circuits
Compensation mechanisms to maintain cardiac output if stroke volume is reduced
●↑ Adrenergic activity → increase in heart rate, blood pressure, and ventricular contractility ●Increase of renin-angiotensin-aldosterone system activity (RAAS): activated following decrease in renal perfusion secondary to reduction of stroke volume and cardiac output ●↑ Angiotensin II secretion → vasoconstriction → ↑ systemic blood pressure → ↑ afterload ●Kidney: vasoconstriction of the efferent arterioles and, to a lesser degree, the afferent arterioles → ↓ net renal blood flow and ↑ intraglomerular pressure to maintain GFR ●↑ Aldosterone secretion → ↑ renal Na+ and H2O resorption → ↑ preload
