B4M1 Lecture 8: Congenital Heart Disease (Part 1 & 2) PDF
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These lecture notes detail the formation and development of the heart in utero, focusing on congenital heart disease. The document explains the process of cardiogenesis, highlighting the critical first trimester and the influence of factors like infections on cardiac structure.
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ARDIAC MORPHOGENESIS C here will be endocardial cells in the middle T Our heart starts with a simple tube....
ARDIAC MORPHOGENESIS C here will be endocardial cells in the middle T Our heart starts with a simple tube. which will help in the completion of the ○ There will be fusion of mesodermal ventricular septumof the valves. cells in the very beginning and it will form this simple tube. n the3rd week of gestation(in utero), the O ow this atrial septum, we call it the primum N simple tubes will start to contract like the septum, migrates downward leavingaspaceon contraction of an adult heart. the top. It evolves while contracting, so in probably the fourth weekof fetal life, thissimple tube undergoes certain “looping.” nother membrane develops to the right of this A primary membrane which we call thesecondary membraneleaving a space in between. ○ Which we eventually call thepatent foramen ovale. ○ or example, it moves to the right and F this will form the primitive great arteries, and the primitive pulmonary veins ○ This will form the primitive left ventricle and this will form the primitive right ventricle, so it keeps on contracting. And if we look inside this tube, one will appreciate development of the ventricular he completion of this evolution of structures T septumand theatrial septum willbetowardsthesecondtothethirdmonthof life. Any insult to the development of the heart will result in structural abnormalities. ○ The baby will be born with congenital heart disease. B4M1 Lecture 8: Congenital Heart Disease (Part 1) 1of 15 ○ or example, if the mother during the F our heart beats automatically and regularly Y first trimester contracts infection because the cells in the SA node are naturally (COVID, german measles), it will leaky to sodium. produceaninsulttothedevelopmentof ○ Recap of physiologyofactionpotential the structures so the heart will be in muscle: abnormal. When the baby is born, the The resting membrane baby is expected to have some potentialinthecardiacmuscle structural abnormalities. is negative so when the In other words, the first three months of sodium channel opens up, pregnancy is the most critical period of sodiumwillrushinsidethecell cardiogenesis. which raises the cell ○ Anything that disrupts the evolution of membrane potential from these structures will resultinstructural negative to positive. abnormalities in the heart. Oncethesodiumchannelgoes If the development of the heart proceeds inside the cell, it will become normally,thiswillbecomechambersoftheheart positiveandthereyouhavethe and connections of the pulmonary veins. electrical current. Primitive great arteries will also undergo ○ In the muscles in the heart, the action septation. potential is different. ○ It is originally a single tube andthenit The plasma membrane is produces septation: naturally leakytosodium,soit One will become the aorta , doesnotwaitforthesodiumto and open. One will become the Because of the natural pulmonary artery leakiness of the membrane, Theprimitivepulmonaryveinswillnowattachto there will be pumping of the the left atrium. heart — automatic beating of If there is an abnormalityinthedevelopmentof heart (automaticity). the great artery, some of these will have transpositions. ○ Sometimes there will be failure of septation - so instead of a normal pulmonary artery separate from the aorta, there will only be one like in truncus arteriosus. Sometimes, these connections going to the left atrium do not connect to the left atrium—they connect somewhere else like total anomalous Normal conduction : SA Node to AV Node to pulmonary venous return or partial anomalous undle of His (Left and Right). B pulmonary venous return. WhenthecellsintheSAnodebecomepositive,it Therearealotofcongenitalheartdiseasesthat will affectthejunctionsbetweenthecellswhich will result simply because of insult during the will make the other cells positive. development of the heart during the first ○ This process is calleddepolarization. trimester of pregnancy. When the muscles of the ventricularpartofthe The heart contracts even as early as 3 weeks. heart are depolarized then the heart contracts. ○ Because of action potential coming ○ Whenitcontracts,itejectsblood—this from theSA node. is thestroke volume. We have a normal pacemakeratthejunctionof Stroke volume x Heart Rate = the right atrium and the superior vena cava. Cardiac Output ThisSAnodeisthepartoftheheartthatserves After depolarization, it returns to arestingstate action potential ,electricalpotential,thattravels called repolarization and this electrical current to the right atriumtotheAVnodetotheBundle can be detected byelectrocardiogram. of His (right and left). B4M1 Lecture 8: Congenital Heart Disease (Part 1) 2of 15 P wave: The depolarization of atrial chamber Higher oxygen contentin utero:Left atrium ○ When the action potential reaches the ○ Travel of blood from the Left atrium: AV Node, the latter“stops”itanditwill Left atrium→Leftventricle→ release it in the Bundle of His, so you Aorta → Brain and Coronary have the QRS arteries QRS complex: Ventricular depolarization These organs receive more T wave: Ventricular repolarization; resting state oxygen in utero. Higher blood volume content in utero: Right ETAL CARDIAC FLOW F ventricle Gas exchange in adults:Lungs ○ WillreceivethebloodfromtheSVCand Gas exchange in fetus (in utero):Placenta a portion of the blood from the IVC. Fetal lungs do not participate in respiration. ○ Right ventricle has greater cardiac Placenta is connected to the fetus through the output and workload than the left umbilical cordwhich connects to the inferior ventricle. vena cava. ○ This is why the fetal right ventricle is more dominantinneonates and infancy This is detected by ECG. Infant and Neonates normal ECG finding: Right ventricular dominance orRightventricular hypertrophy. RV is thicker in utero thanthe leftbecauseithasmoreblood to inject. ○ BloodfromRV→Pulmonaryartery(but in utero it will not go to the Lungs) → Aortathrough a ductus arteriosus Important Structures for In Utero Circulation: ○ Ductus Venosus ○ Ductus Arteriosus ○ Patent Foramen Ovale Blood from placenta going to the fetus: When the baby is born, we clamp the cord and ○ Contains higher oxygen content cut the umbilical cord. (~35mmHg) ○ Cord cutting is sometimes delayed: ○ Mixes with blood from inferior vena If >3 min, more transfusion cava, which is desaturated (~28mmHg) from the mother to the baby ○ Mixes with blood from superior vena (~25 ml/kg) which can addto cava, which is also desaturated the iron store of the baby for (~12mmHg) thenext6months,sowedelay ○ 50% of blood will go to the liver theclampingforaslongasthe ○ 50% of blood go to the heart baby is vigorous. Patent foramen ovale ○ Prematurepatients:wecannotwait,we ○ Blood from the placenta will “milk” the cord so that there’s another preferentially flow to the left atrium source of blood for the baby. across the patent foramen ovale, but ○ Once we cut the umbilical cord, we therewillalsostillbebloodgoingtothe separate the placenta from the baby. right ventricle. Therefore,therewillbenoflowtogoto ○ ThereisstillbloodfromSVCthatwillgo the ductus venosus. to the right ventricle. Ductus venosus becomes a No blood from the lungs will go to the left atrium. ligament. ○ Only ~5-10% of blood from the Baby breathessotherewillbeasuddendropof pulmonary artery goes to the lungs. the Pulmonary Vascular Resistance. ○ Blood will now flow to the lungs. ○ IncreasebloodflowofbloodtotheLeft Atrium B4M1 Lecture 8: Congenital Heart Disease (Part 1) 3of 15 ○ Cause the closure of the foramen ovale When it flows to the lungs: InUterotheflowofbloodisfromthepulmonary ○ The air we breathe contains 21% O2 artery to the aorta via the ductus arteriosus. When we breathe this 21% will When the baby is born, when there is already go to the blood that reaches expansion of the lungs, when there is already the ductus decreaseofvascularresistance,thebloodwillno Causing now the blood to longer flow through the ductus arteriosus reach a higher O2 because the blood will flow from the left and concentration (~95%) right pulmonary artery. The oxygen saturation on the Left side is The pressure in the pulmonary artery decreases. normally always higher on the left side of the ○ Bloodfromtheaortawillnowgotothe heart compared to the right lungs ○ Rememberthatthebloodfromtheaorta is highly oxygenated because the child is breathing. The ductus arteriosus is highly sensitive to oxygen. ○ Contains circular muscles which when exposedtooxygenwillcontractcausing thesmoothmusclestoclosetheductus arteriosus. Within 10-15 hrs after birth the ductus arteriosus will close functionally. Therearesomeconditionsthatmaketheductus arteriosus patent as well as the foramen ovale patent, for survival. LOOD PRESSURES B REVIEW OF NORMAL CIRCULATION This pressure comes from theR. subclavian ORMAL ANATOMY N arterywhich is connected to the aorta. Aorta: Has 3 brachiocephalic branches Systolic & Diastolic pressure: L and R Atrium ○ That is read in the BP cuff is the same L and R Ventricle pressure that is in the aorta. Septum During systole the aortic valve opens, so the Pulmonary veins and arteries pressure in the L. Atrium and Ventricle should be the same. XYGEN SATURATION O During diastole, the aortic valve is closed and there is no communication between the aorta Gas exchange occurs in the lungs, the blood and the left ventricle, so the pressure will be there will go to the left atrium, so it is highly different from what is read on the BP cuff. saturated in oxygen ( > 95%) The BP of the L. Ventricle will be based on the L. ○ Normal flow: Atrium since during diastole the mitral valve Lungs → L. Artium → L. opens since this is the process of ventricle filling. Ventricle → Aorta → Systemic The closure of the Atrioventricular valves mark circulation the end of diastole In all places the oxygen saturation will be the The mean pressure of the L. Ventricle is the same. same as the mean pressure of the L. Atrium = The venous circulation has low oxygen 5-8mmHg. concentration. ○ This is emphasized, since oxygen and When blood arrives at the right atrium it is ~75% pressures will be discussed during in oxygen saturation. these abnormalities. ○ Normal Flow: On the right side of the heart, the Pulmonary R. Atrium → R. Ventricle → artery has20-25%of the pressure of the aorta. Pulmonary Artery Normally it is 25mmHg. ○ Above will all be 75% in O2 concentration B4M1 Lecture 8: Congenital Heart Disease (Part 1) 4of 15 ○ he systolic pressure in the R. ventricle T ain, we might suspect heart g will be the same (25 mmHg) because failure. So this is the postnatal during systole the pulmonary valve is development. open, making it one chamber. hysical exam P ○ The diastolic pressure will be different ECG because the pulmonic valve is CLOSED. Chest X-ray ○ The pressure will be similar to the mean 2D echocardiogram diastolic pressure of the R. atrium (3-5mmHg). CRITICAL CHD SCREENING Example there is a hole in the ventricular septum, e now have screening procedures in the W what would you expect of the blood flow? neonatal period to determine if we are dealing ○ Theblood flow will be dictated by the with critical congenital heart disease. pressures. Cyanotic babies without operation die during the ○ Thepressure is higher in the left first year of life. This example is critical. ventricle, therefore the blood will flow So what do we do? Routinely in all hospitals, we from the left to the right. dopulse oximetry screening. What will happen to the oxygen saturation of the ○ When a baby appears well after 24 left ventricle? hours of life, we do pulse oximetry ○ This is called shunting. screening on the right hand. ○ It will not decrease. ○ If the oxygen saturation is between ○ However, oxygen saturation will 90-94%, we immediately do increasein theright ventricle, echocardiographic evaluation. left-to-right shunt. ○ If the oxygen saturation is around 90%~, What will happen to the oxygen saturation in the you do not detect cyanosis. pulmonary artery? If there is pulmonary stenosis, ○ You can only detect cyanosis ofless what will happen to the blood flow? than 85%. ○ Because there is obstruction, the blood ○ You don’t have to do pulse oximeter will flow from theright to the left. Thus, screening if the baby is already cyanotic, the oxygen saturation will godownand instead directly do a workup. the patient will become cyanotic. For well appearing babies, asymptomatic, you have to do pulse oximeter screening on the right. REVIEW OF NORMAL CIRCULATION ○ if O2 saturation is less than 94% at hen we suspect the patient to have a W room air, we recommend evaluation. congenital heart defect, we will try to evaluate. Why is the right hand used? ○ The ductus arteriosus normally is TOOLS FOR EVALUATION connected to the left distal subclavian istory (especiallymaternalandpostnatal H and left pulmonary artery. history) ○ Hence, if we get the oxygen saturation ○ Ask the mother if they had infection from the left, it is potentially during the first 3 monthsof pregnancy. contaminated by the blood from the ○ Advise patients to receive MMR pulmonary artery. To remove that bias, immunization prior to pregnancy. then we go to the right. There’s a high possibility of the baby And not only the right, we compare it to the O2 developing many abnormalities (small saturation of the lower extremities. head, cataracts, congenital heart ○ If they’re the same with any of the lower disease) if the mother contracts limbs and within the range, then it is measles during the first 3 months of normal. pregnancy. If there is adifference of more than 3%, such as ○ During the feeding of a baby, sweating the upper right limbs are higher than the lower, on the forehead is a sign of heart failure they should undergo evaluation. because of increased catecholamine This is the rule of pulse oximetry screening in levels in the baby neonates. ○ Weight ○ We do not appreciate cyanosis unless Take a look at the weight at the O2 saturation is less than 85% at birth. If there is poor weight room air. B4M1 Lecture 8: Congenital Heart Disease (Part 1) 5of 15 ut if the mother complains that the baby seems B cyanotic, not all cyanosis is secondary to PHYSICAL EXAMINATION OF THE PATIENT congenital heart disease so we have to evaluate. When examining children 1 - 3 years old,start Postnatally, sometimes the presentation with the less disturbing or uncomfortableto the murmurs. baby. ○ One should remember, the majority of If the baby is asleep, directly do auscultation infants will have a murmur. But the because once the baby cries, you won’t be able to murmur in majority of the cases are auscultate clearly. functional or innocent murmur. We can Don’t separate them from their mother or hear vibrations of the structures of the caregiver, also do not force them to lie down. heart. Some mothers would let their children watch ○ And because of the proximity of the videos also. heart to the surface of the chest, we can Do not do percussionwhen evaluating the appreciate those vibrations that are cardiovascular system of a child. mostly described as murmurs. ○ If you percuss their chest, they might It would be difficult for general pediatricians to cry. detect functional murmur. Palpation-Auscultation-Inspectionwill give you ○ That's why we need the cardiologist information. available to evaluate. ○ These days there are a lot of 2D Inspection echocardiogram machines in many hen starting with inspection,observe the W hospitals so the tendency done by most overall facieof the child. cardio pediatricians is to refer to a 2D ○ Do they have dysmorphic features? echocardiogram procedure, but we are Such as the congenital absence of the in the better position to decide whether thumb. a 2D echo is necessary or not to avoid ○ Or absent radius or small shoulder, you unnecessary expenses. might be dealing with Holt-Oram ○ At the same time, if patients are referred syndrome. properly, pediatric cardiologists can ○ Associated congenital anomalies guide the evaluation of the include atrial septal defects. echocardiogram or what needs to be For example you see a baby girl withredundant identified. neck skin, it might mean that you are dealing ○ Not all patients need a 2D withTurner’s Syndrome echocardiogram as it is also expensive. You’ll then know what to look for such as The evaluation of a cardiologist is important, to coarctation of the aorta know whether it is a functional, innocent, or There are features that will help you identify what organic murmur. the association heart condition is. What needs to be identified is also accounted for Another example would be in individuals with so that the accuracy of the echocardiogram and Down Syndrome evaluation will be increased. This way the ○ Features: Flat bridge, upslanting patient’s family won’t have unnecessary palpebral fissure, large tongue expenses. ○ Take note: There are normal individuals Also we can advise, if a patient has a functional with simian crease murmur, some mothers will become worried and ○ Characteristic feature: If there’s only one won’t allow their children to cry or move around, crease in the fifth digit which are unnecessary. ○ May be associated with murmurs, ○ This is because there is a mentality tachypnea, endocardial cushion defect wherein if a child has heart disease, or atrioventricular septal defect they are not allowed to run or play ○ In the nursery, if you see a baby with around. features similar to Down Syndrome, do not label the patient immediately with Down syndrome You look at the parents first. B4M1 Lecture 8: Congenital Heart Disease (Part 1) 6of 15 male Down Syndrome A ○ ou should also know that you cannot Y cannot procreate and a female use the adult cuff for a pediatric patient Down Syndrome has a very low and vice versa fertility. ○ If you use an adult cuff to a pediatric ○ The only way we can confirm it is patient, there will be false decrease of throughkaryotyping= Trisomy 21 the blood pressure There are 3 chromosomes of Too wide BP cuff will produce pair 21 a reduce blood pressure Usually it comes from the Too narrow cuff will increase maternal side, there is no the blood pressure splitting of pair 21 or there is ○ How do you then determine the additional chromosome from appropriate size for the extremity? the father You take note of the width of ○ 50% of individuals with Down Syndrome the cuff and it must be able to have congenital anomalies of the heart cover 50% of the The most common: circumference of the extremity Atrioventricular Septal Defect (Bladder length/sizeof the BP These are just examples of Inspection where the cuff) dysmorphic features will help you conclude what This is the most recent associated congenital anomalies of the heart recommendation are. Too narrow, it will rise. Too Another thing we have to look for in the wide, blood pressure will go inspection is thenature of the chest down. It will not give you the ○ You can have Harrison’s groove (sulcus accurate reading of the blood in the diaphragm) pressure. When you see this, you are You can also palpate whether there is thrill or dealing with a left to right none in the chest. shunt ○ When you say thrill, it’s not the thrill of These are some of the features by inspection palpating the chest. It’s a palpable that can aid the diagnosis murmur. ○ You can only appreciate the thrill if the Palpation murmur is loud. In pediatric patients, we encourage you to Grading of murmurs: palpate the femoral, radial, and brachial arteries ○ Grade 1,2,3,4,5,6. and compare the volume of pulse ○ When there is thrill, it can not be grade If you have a weak femoral pulse with a strong 3. It is grade 4 and above brachial pulse ○ Grade 5, even if you turn your ○ Diagnosis:Coarctation of the Aorta stethoscope sideways you can still hear If there is a strong femoral pulse with a weak the murmur as long as the earpiece is in brachial pulse in an adult place ○ Diagnosis:Reverse Coarctation ○ Grade 6, when you lift the chest piece, When there is no pulse → dead you can still hear the murmur By justcomparing the volume of pulse in the ○ There is little relevance in the intensity upper and lower extremities, you can already of the murmur. What ismore relevant is form a conclusion as to what you are dealing where you hear the murmur. with. In adolescents, do not immediately palpate the Auscultation femoral artery so you may use other pulses In physical diagnosis, we were taught to (radial, brachial). auscultate in the 4 clinical valve areas of the ○ But in children, this must be palpated. chest. That is not the recommended way to One of the things we have to emphasize in auscultate for murmur. palpation is theblood pressure ○ The proper way to auscultate for ○ You should be taking the blood pressure murmur is toimagine a big figure 8and ideally in all upper and lower extremities then you follow that figure so that you won’t miss anything. B4M1 Lecture 8: Congenital Heart Disease (Part 1) 7of 15 ○ If you only concentrate on the 4 valve Duringsystole,Pulmonaryisopen,aorticisopen, areas, you might miss murmurs. itral is close, tricuspid is close. m During diastolic, Pulmonary is close, aortic is The heart sounds. close, mitral is open, tricuspid is open. ○ S1 and S2 are very important. ○ S1is due to theclosure of the ECG atrioventricular valve(the tricuspid and henECGare your guides on the physical exam. T mitral valve). Theright ventricleis dominant (more function ○ S2is due to theclosure of semilunar ”trabaho” than the left). valves( aortic and pulmonic) Comparing ECG of an adult and pediatric patient, When we say physiologic splitting of the S2 there are very noticeable differences. (there are 2 sounds in the S2: the closure of the ○ TheT waveon theright precordial leads aortic and pulmonic valve): innormal childrenisinverted. ○ The splitting widens during inspiration. Why do we emphasize this? ○ But during expiration, the splitting ○ We receive a lot of ECG traces that becomes single. concludeanterior wall ischemia ○ S1 is “lub”; S2 is “dulub” which is split. (kuyawan ang ginikanan). But inversion of the T wave is normal in this case. If you see anupright T wavein a very young patient that isright ventricular hypertrophy. We can see after 72 hours (3 days) of life the T wave ofV1andV2is upright , that means it’s not normal , that is right ventricular hypertrophy. ○ There is no other interpretation on that ECG with an upright T wave on the V1, V2, V3 after 72 hours except for right hen one of the semilunar valves is not W ventricular hypertrophy. functioning: This is a very noticeable finding in an adult and ○ Maybe it’s closed like in tetralogy of pediatric patient. fallotorpulmonaryvalveatresia.Thatis ○ And the other one is the presence of the significanceoflisteningcarefullyto dominance of the R wavein theQRSon the heart sounds. theright chest leadsin the pediatric The 3rd and 4th heart soundisusuallyheardin patients. heart failure. Murmur can be diastolic or systolic. Chest X-ray ○ You can differentiate systolic murmur ven if you have a basic lecture as we go along E from diastolic murmur because the the discussion of certain congenital duration or interval of s1 and s2 is abnormalities of the heart I will present to you shorter the typical findings like intetralogy of Fallotwith ○ The interval between s2 and s1 is wider a “boot-shaped heart”. Ifthemurmuriswithyourpulse,thatissystolic We will discuss again that if we touch a specific murmur. congenital disease, there are radiologic findings ○ If there is murmur that does not that have characteristics to each one of them so coincide withthepulse,that’sdiastolic it will also be included. murmur. And the other thing will be evaluation of patients Insystole,theaorticandpulmonicvalveisopen with heart disease is2D echo, we can see the and the atrioventricular valves are closed. anatomywith 2D echo. ○ In diastole, theaorticandpulmonicare It is a significant tool in the evaluation of patients closed and the mitral and tricuspidare with congenital heart disease. open. When the baby is born (delivered), it’s either the No sounds when opening ofthevalves,it’sonly heart is normal or the heart is abnormal. the closure of the valves where you can appreciate the sounds. B4M1 Lecture 8: Congenital Heart Disease (Part 1) 8of 15 Forexample: ○ Anemic patient with cyanotic congenital heart disease, you cannot detect cyanosis even if the oxygen saturation is less than 85 (Can only be detected when it is too low of saturation). ○ If polycythemic babies have high hematocrit, you can detect cyanosis even if the oxygen saturation is still high. ○ So the hemoglobin which carries the oxygen has a contribution when we detect cyanosis. You need3-5% of hemoglobinthat cannot carry hen the heart is abnormal at birth it is called W oxygen to develop cyanosis. congenitalheartdisease,sotheywerebornwith ○ When the hematocrit forexampleis 20% structuralabnormalitiesoftheheartorbornwith (3-5g of 20=15%) so 15% of the normalhearttheneventuallytheyhavedeveloped hemoglobin cannot carry oxygen and heart disease so they have acquired heart therefore in the patient with 20 disease. hematocrit and 20 hemoglobin at Examples of acquired heart disease: oxygen saturation of 85% or below you ○ Rheumatic heart disease will appreciate cyanosis but in patient ○ Complication of Kawasaki (Kawasaki with 6 hemoglobin, the 3% of the disease) reduced hemoglobin is 50%. ○ Complication of viral infection ○ You will only detect cyanosis when the (Myocarditis) oxygen saturation is less than 50%. We also have patients with congenital heart Inpolycythemia babieswhich have high disease, the prevalence with congenital heart hemoglobin and hematocrit we can detect disease is about 8-12 per 1000 live births or cyanosis even at a higher oxygen saturation. roughly 1 per 100 livebirthsandifwegivethis Inanemic babieswe can only detect cyanosis as the prevalence this does not include mitral when at its very low oxygen saturation valve prolapse, PDA and premature patients. Knowing thelevel of hemoglobin and hematocrit has a big impact in detecting patients with CATEGORIZATION OF CHD potential cardiac problems. ongenital heart disease can probably be C Where do you want to examine the patient for the categorized simply asAcyanoticandCyanotic. presence or signs of cyanosis? This is the general or genetic categorization of ○ Can be nails (but can be affected with congenital heart disease. environmental temp) ○ Acyanoticcan be volume overload or ○ Tolook for cyanosisyou have to look for pressure overload. warm and moist areas of the body Pressure loaded type which (Vocal mucosa) includes: That is the best location to Pulmonary valve detect cyanosis. stenosis Aortic valve stenosis imple S categorization of the Structural Coarctation of aorta Abnormalities of the Heart ○ Cyanoticcategories with increased cyanotic with volume overload and pressure A pulmonary blood flow and normal or overload decreased pulmonary blood flow. Volume overloadwould indicate aleft to right Before going with specific congenital heart shunt(an overload in pulmonary blood flow) diseases I’d like to emphasize that thelevel of ○ Volume overload can be at any level of hemoglobinwill contribute to detect whether you the heart; It can beatrial will have cyanosis or not. communication, ventricular-septal communication , great artery B4M1 Lecture 8: Congenital Heart Disease (Part 1) 9of 15 ommunicationor acombinationof any c Why are they asymptomatic early in life? of these. ight ventricle is thicker than the left ventricle at R Pressure overloadindicates an obstruction, they birth and it will take time before the left ventricle are not cyanotic. thickens. ○ It could be at the area of the pulmonary Due to the thickened right ventricle, it is not valve (PVS), aortic valve or beyond compliant (less compliance) therefore, the shunt (AVS), aorta (COA), or aortic arch (IAA) in the young is less. Again theydo nothave cyanosis because they Magnitude of shunt in ASD is governed by are predominantly left to right shunt. compliance of the right ventricle and the size of These patient will not be acyanotic forever, if they the hole. are not managed or operated, the pressure in the If compliance of the right ventricle increases as lungs, because of increased volume, will continue the patient grows older → there will be more left to increase until it becomes irreversible to right shunt → more blood will go to the lungs pulmonary hypertension (right to left shunt) and → more signs and symptoms will be detected. when that happens will lead to a reversal of the shunt and they will become cyanotic resulting in Signs and Symptoms a condition calledEisenmenger complex. achypnea T Other surgeries cannot be done aside from total Dyspnea heart and lung transplant (which is almost Failure to gain appropriate weight impossible). Increase frequency of lower respiratory tract infection (if there is volume overload) ACYANOTIC CONGENITAL HEART DISEASE ○ Normally, a baby growing up will have lower respiratory tract infection at least ATRIAL SEPTAL DEFECT every 2 months here are several types of atrial septal defects T ○ Baby with ASD will have an infection and the most common isventricular septal every month or more frequent than defect normal The incidence of ventricular septal defect is about30-40%in comparison to ASD (Atrial PE Findings septal defect) which is7-8%. Auscultatory This is the more common congenital heart ○ Fixed and wide splitting of S2 disease that is detected inadulthoodbecause (pathognomonic of a patient with ASD) they are asymptomatic. ○ Relative systolic murmur that may be ASD, in the area of thepatent foramen ovale, is heard is not because of the shunting of calledSecundum ASD blood but, because ofrelative If the ASD is in the area of theprimary membrane pulmonary stenosis we call itOstium primum ASD Electrocardiogram If the ASD isnear the origin or the attachment of ○ Right ventricle will have volume the superior vena cava, it is termedVenosus type overload → right ventricle hypertrophy of ASD (depending on the magnitude of shunt) ○ Secundum ASD, more common type of ○ There couldneverbe a left ventricular ASD, has a small chance (can reach as hypertrophy because there is no left high as 87% chance) of spontaneous volume overload closure during thefi
