الجمعة، 19 أكتوبر 2012

MCQs In cardiology


Q 1:

An 8-month-old girl who has a history of cardiomyopathy following viral myocarditis presents
with poor weight gain. She is receiving a 20-kcal/oz milk-based formula and has no history of
vomiting or diarrhea. Her only medication is furosemide. Physical examination findings include a
heart rate of 130 beats/min, respiratory rate of 60 breaths/min, and blood pressure of 88/44 mm
Hg. Of the following, the MOST appropriate initial strategy to increase weight gain for this girl is to

A. change to a 24-kcal/oz formula
B. discontinue furosemide therapy
C. increase the volume of 20-kcal/oz formula
D. place a gastrostomy feeding tube
E. start parenteral nutrition

Answer :

A

Young infants who have cardiac dysfunction, such as the girl described in the vignette, often have difficulty ingesting sufficient calories for growth because they frequently have increased caloric expenditure with feeding.

 Increased caloric intake may place the infants at risk of fluid overload, necessitating the use of diuretics.

Because an increased volume of feedings with a 20- kcal/oz formula may place the infant at risk of fluid overload, use of a more concentrated formula is required. Accordingly, the infant described in the vignette should be changed to a 24-kcal/oz formula. 

Increasing the caloric density of feedings can meet the goals of increased calories and "relative" fluid restriction.


Discontinuation of furosemide likely would lead to weight gain from fluid retention, not a true
weight gain.

 A gastrostomy tube provides a conduit for feeding and probably plays a role in a child incapable of taking in sufficient calories (eg, chronic renal failure or severe developmental delay), but the child in the vignette deserves a trial of high-calorie feedings before subjecting her to this surgical procedure.

Finally, parenteral nutrition is not a suitable option because this child has a functional gastrointestinal tract and can tolerate enteral nutrition.


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Q 2:

Three weeks after birth, an infant weighs 1 lb (0.45 kg) less than his birthweight. His parents report that he sweats with feedings, which take more than 30 minutes. Cardiac examination reveals a gallop rhythm and systolic ejection murmur. Pulses are equal in the upper and lower extremities. Echocardiography reveals a normal cardiac anatomy, biventricular enlargement, normal to mildly decreased systolic performance, and an abnormally enlarged innominate vein.Which of the following is MOST likely to be present?

A. continuous abdominal bruit
B. continuous cranial bruit
C. systolic abdominal bruit
D. systolic costovertebral bruit
E. systolic cranial bruit

Answer :

B

Intracranial arteriovenous (AV) malformations are rare causes of fetal or neonatal congestive heart failure (CHF). The steal of systemic blood flow into the venous system results in increased volume work for both ventricles. 

A normal or near-normal cardiac output is delivered to the body to meet the regular metabolic demands of the tissues. An additional, often very large, output also is diverted to the AV malformation, which represents a low-resistance “sink” for arterial blood flow. 

Whether the signs and symptoms of congestive heart failure develop depends on the resistance within the AV malformation. Some AV malformations may divert only a small amount of systemic blood flow to the venous circulation; others that have larger communications and low resistance to flow allow torrential flow.

 In this situation, an audible bruit is likely to be found over the vascular malformation. The noise is continuous and resembles the murmur of a patent ductus arteriosus. 

AV malformations causing neonatal congestive heart failure are found most commonly in intracranial and intrahepatic locations. 

 The other physical findings associated with AV malformations are those of CHF from any cause. 

The large volume of blood returning to the right heart and then to the left heart after traversing the pulmonary vascular bed can be associated with a third heart sound or gallop and a nonspecific systolic cardiac flow murmur.

 Rales and tachypnea result from increased pulmonary blood flow and abnormal diastolic filling of the overloaded left ventricle. 

Distal pulses may seem collapsing due to low diastolic pressure in the arterial system from “run off” of the arterial flow.

 As CHF worsens, the pulses distal to the site at which flow is diverted to the AV malformation diminish. For this reason, a cerebral AV malformation can be confused with coarctation of the aorta. 

Symptoms are those of neonatal CHF, with poor feeding and respiratory distress being most prominent.

On echocardiography, the heart appears normal, except for the enlarged chambers. In the later or more florid stages of heart failure, systolic performance of the ventricles is diminished.

 When the AV malformation is supplied by one of the carotid arteries, this vessel appears enlarged, as does the ipsilateral jugular vein carrying the returning blood from the AV malformation.

If the AV malformation is left-sided and involves return to the vein of Galen, the abnormally enlarged innominate vein can be demonstrated easily on the aortic arch view during echocardiography, as described for the infant in the vignette, which helps to confirm the clinical diagnosis.

 Accordingly, a continuous cranial bruit is most expected for this infant. A continuous murmur or bruit over the liver is common in hepatic AV malformations, but it is accompanied by enlargement of the hepatic veins or the hepatic inferior vena cava on the echocardiogram, not enlargement of the innominate vein. 

Systolic cranial bruits often are heard bilaterally over the temporal bones, particularly in toddlers. These are due to normal systolic flow in the middle cerebral arteries and should not be mistaken for the abnormal continuous bruits of cerebral AV malformation. 

Systolic abdominal bruits also are not unusual in healthy children and adolescents; they are the noncardiac equivalents of innocent systolic murmurs.

 Systolic costovertebral bruits occasionally are found in older children who have renovascular hypertension due to renal artery stenosis. 

 CHF from large congenital AV malformations is similar pathophysiologically to CHF from severe anemia or thyrotoxicosis. 

In the case of profound anemia, however, a large volume of blood is delivered to all of the body’s tissues in an attempt to satisfy a normal metabolic demand with adequate oxygen supply. In the case of severe hyperthyroidism, the demands of the body’s tissues are greatly increased, and the cardiac output increases in response to this demand, with the potential result of high-output heart failure.

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Q 3:


A 2-week-old infant presents with tachypnea, poor perfusion, gallop rhythm, diminished pulses, and hepatomegaly. Arterial blood gas shows metabolic acidosis. Echocardiography reveals critical aortic stenosis
Of the following, the intervention MOST likely to stabilize the infant's condition is:

A. dobutamine
B. epinephrine
C. nitric oxide
D. 100% oxygen
E. prostaglandin E1


Answer :

E


The infant in the vignette presents with severe congestive heart failure and cardiogenic shock at a typical age for critically obstructive left heart lesions, such as hypoplastic left heart syndrome, critical neonatal coarctation of aorta, and critical congenital aortic stenosis. As the ductus arteriosus closes, the early compensatory right ventricular contribution to systemic blood flow and vital perfusion to the kidneys and other organs are lost. The result is rapidly developing severe metabolic acidosis that contributes to myocardial and other organ dysfunction.

            The presentation of affected infants often resembles that of septic shock. A high index of suspicion for congenital left heart obstructive lesions must be maintained for infants who have signs of shock in the first two months of life. These signs include gray color and poor capillary refill, thready or absent peripheral or central pulses, tachypnea and hyperpnea, hypotension, and obtundation.

            In the infant who has presumed septic shock, severe metabolic acidosis, and cardiomegaly on chest radiography, echocardiographic evaluation should be undertaken to exclude left heart obstructive lesions. Base deficit pH values greater than 25 on arterial blood gas measurement are common after ductal closure in these infants. Good clinical outcomes have been described even in infants who present with pH values less than 7.0.
            Essential to good resuscitation of the infant who has shock from obstructive left heart lesions is reopening of the ductus arteriosus. Presumably, once the ductus closes, the spiral of fatal deterioration develops rapidly. Accordingly, a trial of prostaglandin E1 (alprostadil) infusion should be administered even to an infant as old as 1 to 2 months of age to open the recently closed ductus arteriosus. The open ductus allows the right ventricle to provide systemic blood flow when the left ventricle cannot.

            Inotropic agents such as dobutamine or epinephrine may provide adjunctive and supportive therapy, but they will not be lifesaving if prostaglandin E1 is not employed to open the ductus.

              Nitric oxide also is a powerful pulmonary arterial vasodilator. Although it may be a lifesaving treatment for newborns who have severe pulmonary hypertension and inadequate pulmonary blood flow, it is contraindicated in the presence of obstructive left heart lesions.

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Q 4:


A term infant is born with a large ventricular septal defectAt what age is this infant MOST likely to first demonstrate clinical findings of congestive heart failure?:

A. 2 days
B. 2 weeks
C.  2 months
D. 6 months
E. 12 months

Answer :

C


 As pulmonary vascular resistance falls in the first months of life, a significantly higher portion of left ventricular output is shunted through the ventricular defect to the lungs where it returns to the left ventricle. According to Starling’s law of the heart, increased preload is associated with increased systolic ejection performance and enhanced stroke volume. 

Most infants who have large ventricular defects exhibit tachypnea, tachycardia, gallop rhythm, sweating with feedings, diminished volumes of feedings, hepatomegaly, and failure to thrive at about the second to third month of life. 

At this time, the pulmonary vascular resistance has fallen sufficiently to allow for a large shunt through the ventricular defect. It is rare for heart failure to occur in the newborn nursery.

 Neonatal severe myocardial dysfunction from myocarditis or cardiomyopathy may present at this time, but more frequently it presents as hydrops fetalis from intrauterine congestive heart failure. Ventricular defects do not present with congestive heart failure in the first days of life.

            One of the congenital obstructive left heart lesions should be suspected in an infant who presents with congestive failure outside of the newborn nursery but within the first month of life. Such lesions include the hypoplastic left heart syndrome, critical neonatal aortic coarctation, and critical aortic valve stenosis. When the ductus arteriosus closes, the right ventricular contribution to the systemic blood flow is lost. Shock and metabolic acidosis quickly follow the development of more typical heart failure signs such as tachypnea and poor feeding.
            A moderate-sized ventricular defect may have enough pulmonary overcirculation to result in failure to thrive in the second half of the first year of life. However, the development of signs of congestive heart failure would be expected earlier in an infant who has a large and unrestricted defect, typically from 2 to 4 months of life. The systolic murmur of left-to-right shunting across a large ventricular defect may be present in the first weeks of life. However, because of elevated pulmonary vascular resistance, this finding may be subtle or occasionally absent.

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Q 5


A 14-year-old girl has a history of primary amenorrhea and short stature.

Of the following, the MOST likely abnormality to be discovered on careful physical examination is:



A.  continuous murmur under the left scapula

B.  fixed splitting of the second heart sound

C.  isolated dextrocardia on precordial palpation

D.  loud single second heart sound

E.  low-pitched diastolic apical murmur with opening snap

Answer

A



At whatever age Turner syndrome is diagnosed, it is important to be aware of its association with aortic disease, particularly coarctation of the aorta. Bicuspid aortic valve with valvular stenosis or regurgitation also may be seen, but careful physical examination for the signs of coarctation is most important. This includes palpation of both radial and brachial pulses and measurement of blood pressure in both arms. The femoral pulses should be palpated simultaneous with the right brachial pulse (if the two arms have equal blood pressures) to ensure that the femoral pulse upstroke is as brisk as the brachial and that there is no delay in the femoral upstroke. The American Academy of Pediatrics Policy Statement on “Health Supervision of Children with Turner Syndrome” recommends echocardiographic follow-up of affected children to observe for aortic dilatation. Some controversy surrounds the likelihood of significant aortic complications developing in those who have Turner syndrome, although there are reports of aortic dissection during pregnancy (after in vitro fertilization with ovum donor embryo
.
            The auscultatory findings of coarctation may be subtle. There may be a slightly harsh but not loud murmur audible to the left of the spine over the back near the left scapular edge. It often extends throughout systole and past the second heart sound into early diastole. Traditionally, this continuous murmur is attributed to flow within enlarged intercostal arteries that are serving as collateral flow vessels in older patients who have coarctation. However, Doppler assessment of the descending aorta below aortic coarctation reveals a high-velocity jet through the coarctation that peaks during systole but continues during diastole. Therefore, although diastolic runoff in the distal descending thoracic aorta is increased because of arterial collaterals, the murmur of coarctation clearly originates in the descending aorta over which it is heard in the posterior hemithorax.

            In patients who have Turner syndrome, auscultation at the cardiac apex may reveal what sounds like a widely split first heart sound. In fact, this is the first heart sound followed by an aortic ejection click, a finding indicative of a bicuspid aortic valve with dilatation of the ascending aorta. Fixed splitting or fixed wide splitting of the second heart sound is the hallmark auscultatory finding of significant atrial septal defects, not aortic disease.


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Q 6



A 12-year-old boy had acute rheumatic fever with carditis 2 years ago. His mother has concerns about antibiotic resistance and asks about current recommendations regarding prophylaxis for her son. You recommend continuation of prophylaxis and prescribe:

A. amoxicillin-clavulanate daily
B. azithromycin daily
C. clindamycin daily
D.  penicillin G with procaine IM every 3 weeks
E.  penicillin V daily

Answer

E



Penicillin continues to be the antibiotic of choice for the treatment of group A streptococcal pharyngitis and prophylaxis of acute rheumatic fever. It frequently is used in the treatment of dental, oral, and group B streptococcal infections. The recommended treatment for all stages of syphilis also is penicillin.

            The antimicrobial activities of penicillin G and penicillin V are similar, although penicillin V is less active than penicillin G against Neisseria meningitidis. Both are available as oral formulations, with penicillin V being the preferred oral agent. Penicillin G is available as an intravenous formulation and intramuscular repositories with procaine and benzathine. Procaine penicillin G provides low penicillin concentrations for only l2 hours. Benzathine penicillin G is a long-acting repository providing low concentrations for up to 4 weeks

Both benzathine penicillin G and oral penicillin V are recommended for chemoprophylaxis of recurrences of rheumatic fever.

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Q 7



Five years after successful treatment with doxorubicin for leukemia, a 14-year-old boy develops effort intolerance, dyspnea, and mild ankle edema.

Of the following, the MOST appropriate initial treatment is:



A.  digoxin and oxygen by nasal cannula

B.  diuretic and angiotensin-converting enzyme inhibitor

C.  inhaled beta agonist and inhaled corticosteroid

D.  nocturnal continuous positive airway pressure and oxygen
E.   systemic corticosteroid and doxorubicin chemotherapy

Answer

B



Severe cardiac dysfunction may occur years after treatment of malignancies with anthracycline drugs, most commonly following treatment of childhood cancer with doxorubicin. Patients, who usually are adolescents, present with symptoms of heart failure, including dyspnea and fatigue, as described for the boy in the vignette. Signs on physical examination may include rales, a prominent third heart sound, lateral displacement of the cardiac apical impulse, and ankle edema. On echocardiography, a dilated left ventricle with poor systolic contractile performance is seen, often with mitral valve regurgitation.



            Primary treatment is directed at the signs and symptoms of heart failure. Diuretics are immediately beneficial to affected patients, and angiotensin-converting enzyme inhibition is crucial to long-term myocardial remodeling if such recovery is possible for patients who have cardiomyopathy due to anthracyclines. The angiotensin-converting enzyme inhibitor should be administered cautiously, with gradually increasing doses.



            Digoxin may have some benefit, particularly in its vagotonic effects to slow the elevated heart rate that occurs because of increased sympathetic tone in congestive heart failure. However, relying on digoxin with or without oxygen is inappropriate treatment of advanced congestive heart failure. Bronchodilator therapy with inhaled beta-agonist or corticosteroid class drugs is not a primary treatment for congestive heart failure, although wheezing may be a presenting sign in affected patients. Positive airway pressure is useful for severe sleep apnea, a condition that may lead to right heart failure, but that is not associated with prior childhood malignancy. A late relapse of leukemia requiring additional chemotherapy is unlikely to present with symptoms of congestive heart failure.

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Q 8



A newborn female has a cardiac murmur. Before the cardiologist arrives to evaluate her, she has a seizure. Results of laboratory testing include a serum calcium level of 5.0 mg/dL (1.25 mmol/L). Subsequently, echocardiography reveals an aortic arch anomaly.

Of the following, the MOST appropriate test to obtain now is:



A. brainstem auditory evoked responses

B. electroencephalography
C. fluorescent in situ hybridization analysis of chromosome 22
D. peripheral blood chromosome analysis
E. thyroid function testing

Answer

C


The infant described in the vignette has a number of features of DiGeorge syndrome. DiGeorge syndrome results from abnormal cervical neural crest migration into the derivatives of the third and fourth pharyngeal arches and pouches during early embryogenesis. The pattern of malformations includes hypoplasia or aplasia of the thymus and parathyroid glands and structural abnormalities of the great vessels. The defects lead to the classic clinical manifestations of deficient cellular immunity due to T-cell dysfunction, causing increased susceptibility to infection; hypocalcemia due to absent parathyroid hormone, resulting in hypocalcemic seizures; and aortic arch abnormalities. Some affected infants also have facial dysmorphic features, which can include hypertelorism, short palpebral fissures, short philtrum, micrognathia, and ear abnormalities.

            Most patients who have DiGeorge syndrome are found to have partial monosomy for the proximal long arm of chromosome 22 due to microdeletion of 22q11.2. This microdeletion can be detected by fluorescent in situ hybridization (FISH) using a molecular probe specific for the region. Although the deletion occasionally is evident on routine chromosome analysis, the FISH study is much more sensitive. 

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Q 9


A 12 year old  who has systemic lupus erythematosus develops pericardial tamponade.
In addition to muffled heart tones, the MOST likely finding would be decreased:

A. heart rate during expiration
B. heart rate during inspiration
C. jugular venous pulsation during expiration
D. systolic blood pressure during expiration
E. systolic blood pressure during inspiration

Answer

E


Abnormally decreased systolic blood pressure during inspiration is termed pulsus paradoxus. In fact, this is not a paradoxic response to respiratory changes in intrathoracic pressure. Normally, inspiration creates a more negative intrathoracic pressure, which results in enhanced right atrial and right ventricular filling at the minor expense of decreased left ventricular filling. A phasic increase in heart rate that is modulated by withdrawal of vagal tone compensates for the decrease in left ventricular preload during inspiration as the aortic baroreceptors signal the brainstem that left ventricular stoke volume has decreased by end inspiration.

            During exhalation, opposite changes occur. Left ventricular filling is increased modestly, resulting in a heart rate that slows slightly by end expiration. Normal sinus arrhythmia results from this phasic respiratory change in ventricular filling. These respiratory changes also are primarily responsible for the normal variation in the splitting of the second heart sound that occurs during the respiratory cycle.

            When there is cardiac tamponade from a large pericardial effusion, the normal decrease in left ventricular preload during inspiration is accentuated, and blood pressure falls. In severe tamponade, this inspiratory fall can be detected easily by the absence of a palpable pulse during inspiration and a return of the pulse during exhalation. More subtle degrees of abnormal pulsus paradoxus may be detected by careful auscultation of the blood pressure as the cuff is deflated slowly. The first Korotkoff sound (K1) is heard, but only intermittently at first. The difference between this systolic blood pressure and the pressure at which a constant audible Korotkoff sound appears is the measured pulsus paradoxus. Values greater than 10 torr are abnormal. A measurement greater than 20 torr is considered severe and indicates that cardiac filling is seriously impaired by the effusion around the heart. An abnormally large variation in intrathoracic pressure also can produce a pulsus paradoxus, as during a severe asthma exacerbation.

            Normal heart rate changes during the respiratory cycle generally are diminished because normal vagal tone is removed during expiration. Sympathetic tone predominates during all respiratory phases in the presence of tamponade. Accordingly, sinus tachycardia is one of the signs of cardiac tamponade.

            Jugular venous pulsations may increase inappropriately during inspiration when filling of the right heart is impeded by the large effusion in the pericardial space. This sign is subtle. Increased jugular venous distention is seen in cardiac tamponade without significant change during respiration.

            The systolic blood pressure does fall during both inspiration and expiration once full tamponade results in systemic hypotension. It suggests the imminence of death.

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Q 10



Of the following, the cardiac lesion that MOST requires endocarditis prophylaxis is:


A. ligated patent ductus arteriosus
B. repaired coarctation of aorta
C. repaired secundum atrial septal defect
D. repaired subaortic ventricular septal defect
E. unrepaired secundum atrial septal defect

Answer

B


. Certain congenital heart lesions are believed to have a low enough risk for developing endocarditis that the small risks associated with high-dose antibiotic prophylaxis prior to dental and other procedures seem unwarranted. Congenital lesions in this category include unrepaired secundum atrial septal defect, successfully repaired secundum atrial septal defect, ligated patent ductus arteriosus, and successfully repaired ventricular septal defect.

            In contrast, repaired coarctation of the aorta requires lifelong administration of antibiotic prophylaxis against endocarditis at the time of procedures that could cause bacteremia. Unlike the conditions described previously, there almost always is some residual turbulent jet of blood flow in the area of coarctation repair. Although isolated coarctation may not strictly be considered a cardiac lesion, bacterial endarteritis is possible in patients who have both repaired and unrepaired coarctation of the aorta. In addition, minor aortic valve abnormalities, especially bicuspid aortic valve, are common in the presence of coarctation of the aorta. Although such valvular abnormalities may have no hemodynamic importance, they do represent a risk for endocarditis.

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