NMS Q&A Family Medicine

52 NMS Q&A Family Medicine6. The answer is D. Atrial fibrillation is the most commoncause of acute peripheral arterial blockage. Acuteobstruction is virtually always embolic in origin. Thus,acute thrombosis as a cause of acute arterial obstructionis unusual, and when it occurs it implies pre-existing atheroscleroticdisease with superimposition of a thromboticprocess. All other choices are valid causes of peripheralarterial embolism but not in the incidence of embolismthat is due to atrial fibrillation. Myocardial infarction isthe second-ranking cause of acute occlusion. When thelatter occurs, it can be inferred that there is a significantportion of ventricular wall that is relatively flaccid, adjacentto which there is relative stagnation of blood flow.7. The answer is A. The patient had previously beenexperiencing claudication in one of his calves when hewalked two blocks. Patients with acute arterial thrombosistypically have some risk factors (including male gender)for the development of atherosclerosis and signs orsymptoms of chronic arterial occlusive disease such asclaudication.8. The answer is C. A decrease in the A/B systolic bloodpressure ratio is the earliest and most sensitive indicatorfor peripheral arterial occlusion. To obtain the A/B ratio,one obtains a systolic blood pressure reading on the posteriortibial artery and divides this by the systolic bloodpressure reading in the brachial artery. Cigarette smokingis the strongest risk factor for peripheral arterial occlusivedisease development but is not an indicator for it. Symptoms,bruits, and skin changes and loss of distal pulsesoccur later as the occlusive disease progresses.9. The answer is E, 0.4. A ratio of 1 is normal, as systolicblood pressure is normally slightly higher in the legsthan in the arms. A ratio 0.9 is consistent with somedegree of arterial occlusive disease and 0.4 would indicatesevere disease.10. The answer is A. Descending aortic aneurysms areusually caused by atherosclerosis, although some arecaused by trauma. Ascending aneurysms that are presentedhere are usually secondary to cystic medial necrosisor syphilis.11. The answer is C. As the diameter of an abdominalaortic aneurysm exceeds 5 cm, the chances of rupture risefrom 3% to 12% at 4 to 5 cm to 25% to 41% for over 5 cm.Coexisting coronary artery disease is a common coexistingpathology, as is claudication of the legs. However,these factors have no direct bearing on the chances ofrupture. Note that the abdominal aorta, being “downstream”in the blood distribution from the thoracic aorta,is normally of a smaller diameter and thus is a smallerdiameter tolerated in abdominal aneurysmal dilatation,as compared to thoracic aortic aneurysm.12. The answer is E. Coronary artery disease is the mostlikely cause of death within 5 years of a patient who hasundergone aortic aneurysm surgery. This is the reasonaggressive search for underlying coronary artery disease isindicated before elective abdominal aortic aneurysmrepair. If coronary artery bypass is indicated, it should bedone before repair of the aneurysm.13. The answer is C, chronic obstructive pulmonary disease.Rupture of an abdominal aortic aneurysm is associatedwith larger-diameter aneurysms, hypertension, andchronic obstructive pulmonary disease. Advanced age andpossibly diabetes mellitus correlate with an increase in theincidence of abdominal aortic aneurysm but are not identifiedrisk factors for rupture.14. The answer is A. The best choice among those listedfor medical management of claudication is Cilostazol(Pletal). Cilostazol’s (Pletal) most prominently mentionedeffect is its inhibition of cAMP phosphodiesterase TypeIII, but its clinical effects are not well understood. Thedrug improves walking distance statistically, in controlledstudies, from 28% to 100%. Although nitroglycerin isclinically applicable in coronary artery disease, it has notbeen applied in PVD; pentoxifylline has been in vogue inthe treatment of claudication in the distant past (i.e., 30 to40 years ago and again 5 to 10 years ago after a rebirth),but it has not proven out well in controlled studies. Lisinopril,perhaps the most popular angiotensin-convertingenzyme inhibitor, is useful in achieving relaxation of musculararterioles; thus, effecting after load reduction andprotection of kidney function in diabetes, it has not beenapplied in atherosclerotic PVD. Propranolol, a nonselectivebeta-adrenergic blocking agent, is relatively contraindicatedin PVD.15. The answer is A. D-dimer is quite sensitive for significantthrombus formation. However, it is not greatlyspecific because it may be elevated in the presence of softtissue injury. Complete blood count and sedimentationrate give no specific information regarding an inflammatoryprocess. A/B blood pressure readings are helpful indetermining the presence and severity of arterial insufficiency(see Question 6). Creatine kinase enzyme levels areelevated in myocardial infarction.16. The answer is C. For accuracy and speed, the spiralCT has become the community standard in most areas. Aplain film has nothing to offer in the acute phase, althoughit may show a recognizable infiltrate after a few days—toolate in many cases to prevent further embolism. An electrocardiogramshows nonspecific changes in 70% ofcases (e.g., sinus tachycardia and nonspecific T-wavechanges). Only 5% may show more specific right-sidedchanges such as the new appearance of right axis deviation,