NMS Q&A Family Medicine

Peripheral Vascular Disease 53right ventricular hypertrophy, or P pulmonale. Thus,these are found only in cases of large emboli. A V/Q scandepends on lack of uptake of macro-aggregates of radioactivealbumin in embolized areas of the lung, while theventilation is unaffected. In lung disease, wherein ventilationis obstructed to affected segments of the lung, parenchymaperfusion may or may not be affected. This testwas the standard diagnostic approach until the past 5 years.It is not specific enough, though quite sensitive in highriskcases. Arterial blood gases may show hypoxia andrespiratory alkalosis that is due to hyperventilation, whenpresent in severe cases. The gold standard is pulmonaryarteriography. It is 97% sensitive. Routine use of this studyis somewhat controversial but is indicated in the followingsituations: intermediate or high pre-test probabilitywhen other studies leave doubt of the diagnosis; nondiagnosticV/Q scans; and when diagnosis must beestablished with certainty, when there are relative contraindicationsto anticoagulation. V/Q scan is not lost tothe diagnostic armamentarium for PE as it is quite applicablewhen elevation of serum creatinine constitutes acontraindication for the use of contrast medium.17. The answer is D. Anticoagulation of the patient withDVT and without pulmonary embolus for 6 monthsreduces the risk of recurrence of DVT and PE by 80% to90%. The points of this question to be appreciated are thefollowing. First, LMWH (e.g., Lovenox, enoxaparin) is aseffective as intravenous therapy for this type of case andhas a therapeutic onset of action comparable thereto andrequires no monitoring of PTT. Second, warfarin therapyneeds several days to be brought into therapeutic levels asregulated according to PT values, and it must be startedvirtually concurrently with the LMWH; some believe thatwarfarin should be started 1 day later because of the possibilityof initial increase in coagulability caused by warfarinbefore its anticoagulation effect takes hold.18. The answer is D. The Raynaud’s phenomenon doesnot involve thrombosis principally; it is an arteriolar processinvolving vasospasm in the manual digits that resultsin color changes to white, bluish purple, and red, usuallycycling over a relatively short period in minutes. If it is anisolated phenomenon, it is called Raynaud’s disease. Otherwiseit is associated with vasospastic phenomena attendantto autoimmune diseases. DVT may be associatedwith occult (or overt) malignancy (20% of cases, of which25% are lung cancer) and deficiency of proteins C or Sand of antithrombin III. In addition, it may be associatedwith factor V Leiden mutation, homocystinuria, and paroxysmalnocturnal hemoglobinuria. Mutation in factor Vcauses a poor anticoagulant response to activated proteinC. This defect will not be detected in standard activatedPTT, PT, or protein C assays. Proven superficial thrombosis,after DVT and PE have been ruled out, may be treatedby surgical ligation or chemical ablation.19. The answer is D. The patient in this vignette has hada classic bout of amaurosis fugax (transient blindness),always in one eye. The vast majority of cases are due tosmall emboli from ipsilateral carotid artery stenosis,exceptions being in (usually) young people without vasculardisease. In those cases amaurosis may be caused bychoroidal or retinal artery vasospasm. The amaurosisassociated with carotid artery disease may be partial (e.g.,in the form of a quadrantanopsia), though often in medicalschool the syndrome is described as a complete loss ofvision in one eye. Examination of the carotid arteriesnearly always reveals auscultatory bruits. With or withouta bruit the carotids must be subjected to Doppler studiesor carotid artery angiography. Such examination shouldbe done on an urgent basis concurrently with vascularsurgery consultation. This syndrome is classified undertransient ischemic attack. Timely carotid endarterectomy(CEA) markedly reduces the chances of stroke. Funduscopywould be abnormal only in cases of retinal vasospasm.The remainder of the physical examination, albeitalways a worthy endeavor, is not particularly relevant tothe complaint.20. The answer is C. A carotid Doppler study should bedone. If the stenosis is 60%, then a firm indication forCEA exists. This case is different from that of Question 19in two main regards: Whereas the patient in Question 18was symptomatic, this patient is asymptomatic. Thesymptomatic patient with a transient ischemic attacksecondary to carotid disease, male or female, merits urgentCEA. However, as an asymptomatic man, this patientdeserves a more aggressive therapeutic approach thanwould an asymptomatic woman. The AsymptomaticCarotid Atherosclerosis Study (ACAS) and other subsequentresearch showed that for 60% stenosis, interdictiveCEA reduces the odds of stroke from roughly 11%over 10 years ( 2% per year) by roughly up to 53% ( 1%per year) for the population at large. It has been estimatedthat about 50% of strokes are due to extracranial pathology,accessible to the surgical knife. If men are consideredseparately, stroke reduction by pre-emptive CEA is animpressive 66%. However, if asymptomatic women areconsidered separately, the results are inconclusive. Carotidangiography is reserved for cases in which surgical indicationis less than clear. Daily aspirin is a normal part ofsecondary prevention (and primary prevention for disease-freeadults over the age of 50 or so), for the inhibitionof platelet aggregation. Before any vascular surgery isto be performed, studies of the coronary circulation are apart of preoperative evaluation but not a part of the specificdiagnosis of bruits or amaurosis.