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Heart Development and Congenital Heart Defects

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Differential Cyanosis

- Cyanosis of the lower extremities but not the upper body *********** http://www.usmle-forums.com/usmle-step-1-bits-pieces/805-differential-cyanosis.html

An 8-year-old African-American male is found to have a holosystolic, harsh-sounding murmur upon physical examination. The murmur is best appreciated at the left sternal border, and is found to be louder when the patient squats. Which of the following is the most likely diagnosis? 1. Ventricular septal defect 2. Patent ductus arteriosus 3. Atrial septal defect 4. Tricuspid atresia 5. Aortic stenosis

1. Ventricular septal defect The murmur of a ventricular septal defect (VSD) is holosystolic and best heard over the "tricuspid area", or the lower left sternal border, with radiation to the right lower sternal border because this is the area which overlies the defect.

An infant becomes cyanotic soon after birth. Emergent echocardiogram reveals the aorta originating from the right ventricle and the pulmonary artery originating from the left ventricle. Which of the following interventions can be done to improve the cyanosis until surgical correction is performed? A. Prostaglandin E2 B. Hyperbaric oxygen administration C. Indomethacin D. No intervention is needed

A. Prostaglandin E2 The initial treatment of TGA is starting PGE to keep the ductus open and then surgical repair

The aorta normally arises _________________ (anterior/posterior) and to the ____________ (left/right) of the pulmonary artery In Transposition of Great Arteries, the aorta arises _________________ (anterior/posterior) and to the ____________ (left/right) of the pulmonary artery

Normal: Aorta arises posterior and to the left TGA: Aorta arises anterior and to the right

Which type of atrial septal defect (ASD) is more commonly associated with other cardiac defects: ostium primum or ostium secundum?

Ostium secundum: most commonly occur as a isolated defect Ostium primum: often associated with other cardiac defects.

What conditions keep the ductus arteriosus open in utero? What conditions lead to its closure after birth?

In utero, low oxygen tension and high levels of PGE1 and PGE2 keep the ductus arteriosus open. PGE1 and PGE2 are produced by the placenta and oxygen tension is low due to nonfunctioning lungs After birth, PGE levels drop as placenta is removed and the functioning lungs are the main organ that metabolizes PGE. Furthermore, oxygen tension increases after first breath

L-R Shunts are associated with ____________ (early/later) cyanosis R-L Shunts are associated with ____________ (early/later) cyanosis

L-R: *L*ate*R* ("Blue Kids") R-L: ea*R**L*Y ("Blue babies")

Where can the murmur associated with a PDA be best auscultated?

Left Infraclavicular Region

Describe the clinical presentation of patients with PDA

* * * *

Patent Foramen Ovale

* * * * * * * *

Eisenmenger Syndrome

* * * * * * * * *

Describe the formation of the Atrial Septum during embryogenesis

* * * * * * * * * * *

Atrial Septal Defect

* * * *Classified by the location of the defect; the two most common locations are ostium secundum (most common) and ostium primum *Ostium secundum ASDs most commonly occur as a isolated defect, while ostium primum ASDs are often associated with other cardiac defects *Increased risk of stroke due to a paradoxical embolism *Typically asymptomatic in children. May present with exertional dyspnea. *Complications in adulthood include pulmonary arterial hypertension, eventual Eisenmenger Syndrome, atrial arrhythmias, RVH, and rarely right heart failure *Heart Sounds: Midsystolic ejection murmur, loud S1 with wide, fixed split S2 (ULSB) * * *

Match the feature with the Congenital Heart Disorder *"Snowman" Sign *Increased incidence with high altitude *Associated with Maternal Diabetes *Atrialization of Right Ventricle * *Most common Congenital Heart Disorder: * *Boot shaped heart * *Left ventricular hypertrophy plus Left Axis Deviation on ECG *"Egg-on-string" heart *Associated with Lithium exposure in utero

*"Snowman" Sign: TAPVR *Increased incidence with high altitude: PDA *Associated with Maternal Diabetes: Transposition *Atrialization of Right Ventricle: Ebstein Anomaly * *Most common Congenital Heart Disorder: VSD * *Boot shaped heart: TOF * *Left ventricular hypertrophy plus Left Axis Deviation on ECG: Tricuspid Atresia *"Egg-on-string" heart: Transposition *Associated with Lithium exposure in utero: Ebstein Anomaly

Patent Ductus Arteriosus

**More common in females* *Closure usually occurs within 24 to 48 hours of birth *Can be kept open by administering PGE2 *Can be caused to contract and close by administering prostaglandin synthesis inhibitors (i.e indomethacin) *Characterized by a continuous machine-like murmur (best heard over left infraclavicular region) **Loudest at S2* **May be associated with frequent respiratory infections* *Diagnosis: Echocardiography is gold standard

Ebstein Anomaly

*A large portion of the RV is "atrialized" so that the functional RV is very small *cardiomegaly? (due to increased size of RA) *tricuspid regurg? * *Intra-atrial communications such as PFO or ASD is usually present * *https://books.google.com/books?id=LyxNF2kpYqEC&pg=PA511&lpg=PA511&dq=quadruple+rhythm+ebstein+anomaly&source=bl&ots=23xoOT7iQx&sig=XtLIt7GQn1JMdsmOQ8Fb-t9BTrY&hl=en&sa=X&ved=0ahUKEwjs-Oi0opHSAhXh7YMKHVRCBQoQ6AEISTAJ#v=onepage&q=quadruple%20rhythm%20ebstein%20anomaly&f=false *http://mynotes4usmle.tumblr.com/post/76258123133/ebstein-anomaly *http://medicine.ucsf.edu/education/resed/Chiefs_cover_sheets/ebstein.pdf

Describe where the first increase in PO2 develops on the right side of the body, in the following *ASD *VSD *PDA

*ASD: RA *VSD: RV *PDA: PA

Tricuspid Atresia

*Absence of a tricuspid valve; Results in no direct connection between RA and RV *ASD must be present **Associated with Right Ventricular Hypoplasia and therefore decrease pulmonary blood flow *Often associated with TGA; Presence of TGA allows increased pulmonary blood flow and less cyanosis. Viceversa with absence of TGA *The presence and increased size of a VSD also can increase pulmonary blood flow **Presence of Left Ventricular Hypertrophy and Left Axis Deviation on ECG distinguish from other causes of cyanosis* * * * *

Ventricular Septal Defect

*Most common congenital cardiac defect. *Majority of VSDs occur in the membranous interventricular septum **Characterized by harsh holosystolic murmur that occurs at the left lower sternal border* *Smaller defects are associated with a louder murmur and more palpable thrill *Increased risk of stroke due to a paradoxical embolism *Acquired VSD can occur as a complication of acute MI **Small VSDs are typically asymptomatic at birth and spontaneously close* *Large VSDs are associated with LVH, Pulmonary hypertension, and eventual shunt reversal/Eisenmenger Syndrome

D-Transposition of Great Vessels

*The aorta is connected to the right ventricle and the pulmonary artery is connected to the left ventricle. *Due to failure of the aorticopulmonary septum to spiral *Essentially there are two independent and parallel (rather than normal series) blood circuits for systemic and pulmonary circulations *Not compatible with life unless a shunt is present to allow mixing of blood (eg, ASD, VSD, PDA, PFO *Associated with Maternal Diabetes **S2 usually single and loud* *Tx: Initial treatment is starting PGE-1 to keep the ductus open and then surgical repair

Persistent Truncus Arteriosus

*Truncus arteriosus fails to divide into pulmonary trunk and aorta due to lack of aorticopulmonary septum formation *Presents with early yet minimal cyanosis *Deoxygenated blood from right ventricle mixes with oxygenated blood from left ventricle before pulmonary and aortic circulations separate **Most patients have accompanying VSD* *CHF symptoms are commonly present in the infant *Associated with DiGeorge Syndrome *Tx: Treat heart failure and then surgery

A 32-year-old woman presents to the emergency department with 2 hours of left-sided weakness. Her husband reports that she had been complaining of pain and swelling in her right calf for several weeks prior to this event. The couple had recently returned from a vacation in Europe. What ausculatory finding would explain the mechanism by which her more recent complaint occurred? 1. Holosystolic murmur radiating to the axilla 2. Wide, fixed splitting of S2 3. Crescendo-decrescendo murmur heard loudest at the left second intercostal space 4. Holosystolic murmur that increases on inspiration 5. An S2 that splits during expiration

2. Wide, fixed splitting of S2 This woman has suffered a thromboembolic stroke from a deep vein thrombus (DVT). A wide, fixed splitting of S2 is consistent with an ASD, which would allow direct communication from the venous system to the arterial system without traversing the lungs, thereby causing her paradoxical embolism. The only mechanism by which a DVT can result in an embolic stroke is if there is a connection between the right heart and the left heart, such as an ASD or VSD. Signs of an ASD include a wide, fixed splitting of S2.

A 27-year-old woman with a history of a "heart murmur since childhood" presents following a series of syncopal episodes over the past several months. She also complains of worsening fatigue over this time period, and notes that her lips have begun to take on a bluish tinge, for which she has been using a brighter shade of lipstick. You do a careful examination, and detect a right ventricular heave, clubbing of the fingers, and 2+ pitting edema bilaterally to the shins. Despite your patient insisting that every doctor she has ever seen has commented on her murmur, you do not hear one. Transthoracic echocardiography would most likely detect which of the following? 1. Aortic stenosis 2. Mitral insufficiency 3. Positive bubble study 4. Ventricular aneurysm 5. Dynamic left ventricular outflow tract obstruction

3. Positive bubble study This young patient is exhibiting signs and symptoms of right heart failure in the setting of a longstanding cardiac murmur. This combination raises immediate concern for Eisenmenger syndrome, a feared sequela of congenital heart disease comprised of the triad of a right-to-left intracardiac shunt, cyanosis, and pulmonary arterial disease. A bubble study, in which agitated saline injected intravenously appears in the left atrium during echocardiography, is commonly used to diagnose a right-to-left shunt.

A 7-year-old girl is referred to a pediatric cardiologist after a heart murmur was auscultated during a routine school health examination. The patient has not experienced any symptoms of shortness of breath, fatigue, chest pain, or palpitations. She is healthy, does not have any significant medical history, and had an uneventful birth without any complications. Her vital signs are as follows: T 37.2 C, HR 92, BP 104/62, RR 24, SpO2 99%. Physical examination is significant for a midsystolic ejection murmur heard best at the 2nd intercostal space near the left sternal border, a loud S1 heart sound, a widely fixed split S2 heart sound, and no evidence of cyanosis or clubbing. An echocardiogram is conducted and reveals a left-to-right shunt across the interatrial septum. Surgical correction of this patient's condition will most likely prevent which of the following from developing later in life? 1. Arteriovenous fistula 2. Pulmonary stenosis 3. Coronary artery disease 4. Pulmonary hypertension 5. Aortic root dilation

4. Pulmonary hypertension This patient's presentation of a systolic murmur with a widely split, fixed S2 and the above echocardiogram findings is consistent with a diagnosis of atrial septal defect (ASD). Patients with ASD are at risk of developing pulmonary hypertension due to the chronic left-to-right intracardiac shunt. Whether or not a patient is symptomatic or develops complications from an ASD is often dependent on the size of the defect. In the many cases, initially the left-to-right shunting of the blood between the atria through the defect leads to an asymptomatic increase in blood flow to the pulmonary vasculature. Over time and with increasing blood flow, the pulmonary vessels begin to stiffen, resulting in pulmonary hypertension. The elevated pulmonary vasculature pressures lead to increased right-sided heart pressures and eventually reversal of the shunt to a right-to-left direction. Although rare, this shunt reversal, called Eisenmenger's syndrome, is a late and serious complication of an untreated ASD.

How might an ASD cause right sided heart failure?

A chronic left to right shunt increases flow volumes to the right side of the heart, leading to ventricular and atrial dilation, increased stroke work, decreasing pumping ability, and eventually right sided failure

A 46-year-old woman with a history of complex congenital heart disease and cyanosis is evaluated for fatigue and dyspnea on exertion. The patient has had previous palliative surgical intervention but remains cyanotic. She has been managed conservatively for many years, with recent regular phlebotomies. Physical examination demonstrates central cyanosis and digital clubbing. The apical impulse is laterally displaced. There is a parasternal impulse and brief systolic and diastolic murmurs are noted at the left sternal border. The lungs are clear. Laboratory testing demonstrates a hemoglobin of 17.5 g/dL (175 g/L) and a hematocrit of 60%. The platelet count is 150,000/Î¼L (150 Ã— 109/L) and the leukocyte count is normal. A blood smear shows a hypochromic, microcytic anemia. The electrocardiogram demonstrates right ventricular hypertrophy with strain, unchanged from the last evaluation. The chest radiograph demonstrates cardiomegaly primarily affecting the right side of the heart and reduced pulmonary vascularity. What is the most appropriate management of this patient at this point? A Phlebotomy B Short-course iron therapy C Institution of vasodilator therapy D Heart transplant evaluation E Lung transplant evaluation

B Short-course iron therapy This patient has features of relative iron deficiency. Her hemoglobin and hematocrit are low for a patient with palliated cyanotic congenital heart disease. A normal hemoglobin for a cyanotic patient is 18â€"21 g/dL (180â€"210 g/L), and a normal hematocrit is 61% to 65%. The blood smear also demonstrates a hypochromic, microcytic picture. Further evaluation of the cause for iron deficiency is reasonable, but in this case, the likely cause is recurrent phlebotomy. Short-course iron therapy is indicated while evaluation proceeds. Iron 325 mg daily should be administered for 7 to 10 days and stopped when the hemoglobin and hematocrit begin to increase. Prolonged iron therapy may cause erythrocytosis and increased viscosity. Cyanotic patients require higher hemoglobin and hematocrit than noncyanotic patients to allow adequate oxygenation of the tissues. Cyanotic patients should avoid iron deficiency, which can cause functional deterioration and is associated with an increased risk of stroke. Therapeutic phlebotomy may be required for some cyanotic patients but should be reserved for patients with a hemoglobin >22 g/dL (220 g/L) and a hematocrit >65% with symptoms of hyperviscosity (mental slowing, reduced concentration, headaches) and no evidence of iron deficiency or dehydration. Phlebotomy is not indicated for asymptomatic patients. The most common cause of reduced hemoglobin and hematocrit in a cyanotic patient is excessive phlebotomy. The only indication for prophylactic phlebotomy is in the preoperative patient when the hematocrit is higher than 65% to reduce the chances of perioperative bleeding. For symptomatic patients, phlebotomy should be performed with volume replacement. This patient has a relatively low hemoglobin level, and phlebotomy would be contraindicated in this case. Although vasodilator therapy for patients with severe pulmonary hypertension may be helpful, conservative measures should be considered first. Similarly, transplantation may be considered in the future for this patient if functional decline continues, but hematologic adjustment would be indicated initially.

A 6-hour-old female newborn has a harsh systolic murmur at the left upper sternal border. Findings on physical examination are otherwise unremarkable. Three hours later, the murmur has a diastolic component. Twelve hours later, there is no murmur, and ultrasonography discloses no cardiac abnormalities. Which of the following is the most likely cause of the murmur? A) Mitral regurgitation B) Patent ductus arteriosus C) Persistent truncus arteriosus D) Transient tricuspid insufficiency E) Ventricular septal defect with right-to-left shunt

B) Patent ductus arteriosus

A 9 year old boy is brought to the emergency room by his mother because he state " my heart seems really fast and is pounding". This has been occurring for the past 3 hours. He has never complained of this before. In fact, he has been healthy, having had only the typical acute childhood illnesses, and has not even seen a doctor for the past 2 years. Upon auscultation, his heart rate is about 200/min. he is easily converted into sinus rhythm after his face is submerged in ice saline for a few seconds. further examination shows a grade III holosystolic murmur heard over most of the anterior chest along with a gallop rhythm heard over the lower left sternal border. An electrocardiogram is then performed at his normal heart rate and shows a short PR interval with an upstroke of the QRS. Which of the following is the most likely diagnosis? a. Atrial septal defect b. Ebstein anomaly c. pulmonic stenosis d. tetralogy of fallot e. tricuspid atresia f. tricuspid regurgitation

B. Ebstein anomaly

What does the D in D-Transposition of Great Vessels stand for and what does it signify?

D for Dextrotransposition The aorta normally arises posterior and left of the pulmonary artery and ascends behind and right of it. In TGA, the aorta is anterior and right of the pulmonary artery

A 32-year-old woman is evaluated for exertional dyspnea that has developed within the last few months. She reports a lifelong history of a heart murmur, but has had no other cardiovascular symptoms and has not had prior cardiac testing. She recently moved to the United States from North Africa, and she did not receive regular health care prior to moving to the United States. She is not on any medications. On physical examination, her blood pressure is 130/40 mm Hg and her heart rate is 70/min and regular. The jugular venous pulse contour demonstrates prominent a waves and the carotid pulses are bounding. The cardiac apex is displaced to the anterior axillary line of the sixth intercostal space, and a parasternal impulse is present. There is a systolic and diastolic murmur palpable over the left chest. A continuous grade 4/6 systolic and diastolic murmur is noted over the left side of the chest and primarily over the second left intercostal space. There is no S3 or S4. No additional sounds are noted. There is no evidence of digital clubbing or cyanosis. Electrocardiogram demonstrates bi-atrial enlargement and features of left ventricular hypertrophy. Chest radiograph demonstrates cardiomegaly. Which of the following is the most likely diagnosis? A-Atrial septal defect with associated pulmonary valve stenosis B-Eisenmenger syndrome C-Mitral stenosis and regurgitation D-Patent ductus arteriosus E-Ventricular septal defect

D-Patent ductus arteriosus This patient most likely has a patent ductus arteriosus. The ductus arteriosus connects the aorta and pulmonary artery during fetal life. Persistence of the ductus arteriosus after birth is associated with maternal rubella infection. Patients with a moderately sized patent ductus arteriosus may present with symptoms of heart failure, with enlarged heart chambers on the left side. The patient has features of a large left-to-right shunt with associated left heart enlargement characterized by a displaced left apical impulse. These findings suggest that the shunt is beyond the atrial level and rules out an atrial septal defect. The systolic and diastolic (continuous) murmur is most consistent with a patent ductus arteriosus. It is uncommon to find someone with an unrepaired patent ductus arteriosus in the United States; however, this patient was born in North Africa, and she did not have access to health care. This patient would require hemodynamic cardiac catheterization assessment of pulmonary vascular resistance prior to considering intervention. Patent ductus arteriosus closure should be avoided in patients with irreversible pulmonary vascular disease. If the resistance is low, then percutaneous intervention could be considered and would result in reduction of the left ventricular size

A newborn infant is found to be cyanotic immediately after birth. A cardiology work-up reveals an abnormal heart. The newborn's heart has a ventral septal defect with a single, large outflow tract that becomes the aorta and pulmonary arteries. This condition most likely resulted from which of the following? A. Abnormal apoptosis B. Abnormal fusion of the superior and inferior endocardial cushions C. Abnormal fusion of the muscular and membranous ventricular septa D. Abnormal neural crest cell migration E. Maternal cocaine use F. Abnormal mesodermal differentiation

D. Abnormal neural crest cell migration The condition described is persistent truncus arteriosus, which is a congenital cyanotic heart condition. Persistent truncus arteriosus includes a large ventral septal defect and a single, large ventricular outflow tract that becomes the aorta and pulmonary arteries. The mixing of blood between the right and left ventricles results in right-to-left shunting and cyanosis. The condition is most likely caused by abnormal neural crest cell migration and malformation of the aorticopulmonary septum. If not treated surgically, infants usually die by the age of 2. The other choices are incorrect

The murmur associated with PDA is described as a continuous "machine-like murmur" that peaks at S1 T/F?

F! Peaks at S2

A 6-month-old girl is brought to the physician because of poor feeding and labored breathing for 2 months. She has had recurrent respiratory tract infections since birth. Examination shows a to-and-fro murmur in the second left intercostal space, a loud S2, bounding peripheral pulses, and a widened pulse pressure. Which of the following is the most likely diagnosis? A) Atrial septal defect (ostium primum type) B) Atrial septal defect (ostium secundum type) C) Atrioventricular canal D) Coarctation of the aorta E) Hypoplastic left heart syndrome F) Patent ductus arteriosus G) Tetralogy of Fallot H) Transposition of the great arteries I) Tricuspid atresia J) Ventricular septal defect

F) Patent ductus arteriosus

https://books.google.com/books?id=z2f9DAAAQBAJ&pg=PA123&lpg=PA123&dq=transposition+usmle&source=bl&ots=RCLphnepFx&sig=f0xz2-sDliJWsrY7VbMS5aTe5CY&hl=en&sa=X&ved=0ahUKEwiv-MzgjJHSAhVH6GMKHT8VAgo4ChDoAQgmMAM#v=onepage&q=transposition%20usmle&f=false

GOOD SOURCE

Remember that an ostium primum ASD has a right bundle branch block and left axis deviation on the ECG while an ostium secundum ASD has a right bundle branch block and right axis deviation on the ECG

IS THIS TRUE? Copied from Healio

What pharmacologic therapy can be administered to close a patent ductus arteriosus?

Indomethacin Patent ductus arteriosus can be treated pharmacologically with COX inhibitors, such as NSAIDs (e.g., indomethacin), or may require invasive procedures in refractory cases.

What type of shunt results from a patent ductus arteriosus

L->R Shunt (aorta to pulmonary artery)

What are the three congenital heart defects that create left-to-right shunts?

Left-to-right shunts: VSD: Holosystolic harsh murmur (LLSB) ASD: Midsystolic ejection murmur, loud S1 with wide, fixed split S2 (ULSB) PDA: Continuous machine like murmur (Left infraclavicular region)

Name 4 risk factors for Patent Ductus Arteriosus

Maternal Rubella Infection (during 1st trimester) Prematurity *High Altitude*

Why is Congestive Heart Failure a very common finding in infants with Persistent Truncus Arteriosus?

Persistent Truncus Arteriosus is associated with pulmonary blood flow that is about three times more than the systemic circulation and so the amount of blood flow to the lungs increases significantly, giving rise to pulmonary over circulation. The outcome of this would be a Congestive Heart Failure, thus, infants with PTA typically present with CHF (due to the excess amount of blood flowing to the lungs) and are usually in distress during their first few weeks of life

What type of shunt was the ductus arteriosus in utero?

R ->L Shunt (pulmonary artery to aorta; bypassing fetal lungs)

What congenital infection is associated with PDA?

Rubella infection during the first trimester of pregnancy, particularly in the first 4 weeks, is associated with a high incidence of PDA

Heart Development and Congenital Heart Defects

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