السبت، 9 فبراير 2013

MCQs In cardiology- Part II

Q1:

A 12-year-old boy wishes to participate in competitive sports. His father died suddenly at age 28 years, and hypertrophic cardiomyopathy was found on autopsy.
Of the following, the MOST helpful test for assessing the boy's risk is:

A. echocardiography
B. electrocardiography
C. exercise myocardial perfusion scintigraphy
D. genetic testing for myosin chain mutations
E.  genetic testing for troponin mutations

Answer

A


The dominant inheritance of many forms of hypertrophic cardiomyopathy is the rationale for screening examinations of family members of patients who are diagnosed with these disorders. Furthermore, a positive family history of sudden death at a young age from hypertrophic cardiomyopathy, such as described for the boy in the vignette, is a significant risk factor for premature or sudden cardiac death in patients who have hypertrophic cardiomyopathy. Echocardiography is the most commonly employed screening tool for individuals who have such a positive history. 

Electrocardiography results may be very abnormal in adolescents or children who have hypertrophic cardiomyopathy, but electrocardiographic findings may be normal until echocardiography results are abnormal for a longer period of time.

            Exercise myocardial perfusion scanning may have a role in risk stratification for patients who have hypertrophic cardiomyopathy because exercise-related myocardial ischemia appears to be one of the mechanisms for syncope, chest pain, and sudden death in affected patients. However, perfusion scanning cannot be used to screen for the presence of hypertrophic cardiomyopathy

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Q 2


A 12-year-old boy had tetralogy of Fallot repaired at age 2 years. Right ventricular outflow obstruction was corrected with a patch across the pulmonary valve annulus. Now he complains of exercise intolerance and fatigue.
Of the following, the MOST likely echocardiographic finding in this patient is significant:

A. atrial left-to-right shunting
B. atrial right-to-left shunting
C. pericardial thickening
D. right ventricular diastolic volume elevation
E. right ventricular systolic pressure elevation

Answer

D


The functional status of cases years after successful repair of tetralogy of Fallot can be excellent. Nevertheless, significant problems with right ventricular function may occur, the most serious of which is the development of episodic rapid ventricular tachycardia arising from the right ventricle. In some instances, sudden death has been attributed to this complication. 

Repaired tetralogy of Fallot invariably results in some degree of either outflow obstruction to the right ventricle with right ventricular hypertension or abnormal pulmonary valve incompetence resulting in a volume overload to the right ventricle. During ventricular diastole, the normal right ventricular filling through the tricuspid valve is augmented by regurgitation of blood back into the right ventricle from the pulmonary arteries. Often there is some element of both right ventricular pressure and volume elevation.

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Q 3:


A 7-year-old girl presents with chorea and a new murmur of mild mitral valve regurgitation.
Of the following interventions, chronic disability is MOST likely to be prevented by:

A. intramuscular penicillin monthly
B. intravenous penicillin for 6 weeks
C. oral haloperidol for 6 weeks
D. oral prednisone for 4 weeks
E.  oral salicylates for 6 weeks

Answer

A


The most important therapeutic intervention for the patient who has rheumatic fever is chronic antibiotic prophylaxis to prevent group A streptococcal pharyngitis, which could lead to recurrence of acute rheumatic fever. Serious cardiac damage is unusual after an initial attack of acute rheumatic fever, but it becomes more likely with subsequent attacks. 

Administration of intramuscular benzathine penicillin every 21-28 days affords better protection against streptococcal infection than any oral regimen, perhaps largely due to the ability to monitor and ensure compliance with the regimen. Rheumatic fever prophylaxis must continue at least into adult life after rheumatic heart disease has occurred.

            Intravenous penicillin for 4 to 6 weeks is a potential regimen for the treatment of streptococcal bacterial endocarditis caused by the various Lancefield nontypeable strains of Streptococcus collectively termed S viridans.

            Haloperidol has been used in some cases of Sydenham chorea to treat the involuntary movements, but the neurologic sequelae of the chorea associated with rheumatic fever should resolve. Moreover, treatment of the movement disorder has not been shown to have any specific role in preventing permanent sequelae.
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Q4


You are seeing a 4-month-old male infant who has a history of Tetralogy of Fallot. The infant underwent palliation with a systemic-to-pulmonary shunt (Blalock-Taussig shunt) at 3 months of age because of persistent cyanosis. He is scheduled for complete repair at 8 months of age. His mother wants to know if he will have normal development after he undergoes complete repair and his oxygen saturation levels are normal.



Of the following, the MOST appropriate statement about this child’s neurodevelopmental prognosis is that the child is likely to have

A. delayed motor skills
B. normal intellectual functioning
C. profound hearing deficit
D. profound speech delay
E. significant behavioral difficulties

Answer

B

Although the large majority of patients who have Tetralogy of Fallot (TOF) have normal intellectual functioning, it has been reported that about 22% of patients score less than 80 on IQ testing, as compared with 2.8% of the general population. Potential risk factors include prolonged hypoxemia, congestive heart failure, and thromboembolic events. An additional important risk factor is the association of TOF and chromosome 22q11.2 microdeletion, which is found in over 15% of patients with TOF. 

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Q5 :


You are seeing a 10-year-old boy for a health supervision visit. His brother and sister accompany him and his mother to the visit. The mother reports that her husband recently underwent a heart transplant for a “thick heart.” As you explore the family history in more detail, you learn that the boy’s paternal uncle and grandfather both have been diagnosed with hypertrophic cardiomyopathy. The boy has never had chest pain, palpitation, shortness of breath, dizziness, or syncope. He participates in sports and activities without any problems. Findings on physical examination are within normal limits.
Of the following, the MOST appropriate next step is

A. cardiology referral for this patient
B. cardiology referral for this patient and all of his siblings
C. cardiology referral for this patient and his male siblings
D. electrocardiography and echocardiography, followed by cardiology referral if results of either are abnormal
E. genetic testing for the entire family

Answer

B


Hypertrophic cardiomyopathy (HCM). The latter typically is inherited via one of several autosomal dominant genes that encode for the constituents of the sarcomere.




The family described in the vignette carries the diagnosis of HCM, and the children each have a 50% chance of having inherited the HCM gene from their father. Current recommendations suggest regular evaluation (perhaps as often as yearly) of such children, ideally by a cardiologist, involving detailed history, physical examination, and diagnostic testing that includes electrocardiography and echocardiography. Because the HCM gene is inherited in an autosomal dominant pattern without gender preference, referring only the patient in the vignette or limiting evaluation to males in the family risks missing the diagnosis in some siblings.


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