Step 2 CK Review - Cardiology

USMLE STEP 2 CK REVIEW ~ CARDIOVASCULAR ISCHEMIC HEART DISEASE 

Coronary Artery Disease (CAD) o Accumulation of atheromatous plaques within walls of coronary arteries that supply O2 to myocardium   Blood flow causes ischemia of myocardial cells due to lack of oxygen  Effects of ischemia reversible if blood flow to heart improved  Complete occlusion of artery causes irreversible cell death called myocardial infarction o Risk Factors:  DM, HTN, tobacco, age >45, hyperlipidemia,  LDL,  HDL, homocysteine   FHx of premature CAD or MI in 1st-degree relative – men 1 flight of stairs  Class III  Marked limitation of ordinary activity – angina after 4, DM  Invasive  Early coronary angiography & revascularization o Indicated w/following high-risk indicators:  Recurrent or persistent pain refractory to medical therapy  LV dysfunction – EF 60secs  Embolectomy via Fogarty balloon catheter  Thrombectomy  graft  bypass  Amputation  If irreversible ischemia

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Deep Venous Thrombosis (DVT) o Thrombus formation & subsequent inflammatory response in superficial or deep vein o Thrombi propagate in direction of blood flow – MC in LE originating in calf veins 23

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Most important complications are PE (50% risk w/proximal DVT) & chronic venous insufficiency Virchow’s Triad:  1) Endothelial damage  Leads to  inhibition of coagulation & local fibrinolysis  Trauma, major surgery, pelvic procedures  2) Venous stasis  Immobilization inhibits clearance & dilution of coagulation factors  Prolonged bed rest, long flights, orthopedic casts, CHF  3) Hypercoagulability  Hereditary states, OCP, malignancy Clinical Presentation:  Asymptomatic – esp. if superficial venous system patent allowing blood drainage  Classic findings  Seen in 50% – but all have low sensitivity & specificity:  Unilateral LE pain, edema & erythema – improves w/rest or elevation  Homan’s sign – pain w/foot dorsiflexion  Palpable cord – due to thrombosed vein  Phlegmasia alba dolens  White leg w/no ischemia  Phlegmasia cerulea dolens  Cyanotic leg w/severe pain & ischemia  Post-phlebitic (post-thrombotic) syndrome  Pain, edema, hyperpigmentation & skin ulceration  MC complication in up to 2/3 of DVT cases – due to small obstructions still remaining Diagnosis:  vDuplex U/S  Initial test for DVT – high sensitivity & specificity  Only for detecting proximal thrombi (popliteal, femoral) – not distal (calf vein) thrombi   vDuplex  leg symptoms  Rules in proximal DVT   vDuplex w/o leg symptoms  Does not R/O DVT!  Venography  Best test for diagnosis of distal calf vein thrombi – but invasive & rarely used  Visualize deep & superficial venous systems – assesses patency & valvular competence  Impedance Plethysmography  Noninvasive alternative to doppler U/S  High sensitivity for proximal DVT only – but poor specificity due to  false positive rate  D-dimer  Low specificity – may be elevated in MI, CHF, pneumonia, post-operative state  Must be combined w/Doppler to R/O DVT Treatment:  Acute anticoagulation  Unfractionated Heparin or LMWH  IV Heparin  Bolus w/continuous infusion for 5-10d – goal is aPTT of 1.5–2.5x control  LMWH (Dalteparin, Enoxaparin)  No lab monitoring, better bioavailability & as effective  Chronic anticoagulation  Warfarin – continue for 3-6 months or more based on risk factors  Start w/Heparin & overlap for 5+ days until therapeutic INR of 2-3 reached  Thrombolytics  Streptokinase, Urokinase, TPA – indicated in massive PE or RHF  Speeds up lysis of clots – but no improvement in survival  IVC Filter  Indications for Greenfield filter placement:  Contraindication to anticoagulation in documented DVT or PE  Failure of adequate anticoagulation as reflected by recurrent DVT or PE  Low pulmonary reserve w/high risk of death from PE  Preventative  Leg elevation, pneumatic compression boots, compression stockings

Chronic Venous Insufficiency (CVI)  Post-Phlebitic Syndrome o Pathophysiology:  Superficial & deep venous systems connected by perforating veins  Valves allow flow from superficial to deep veins – but not vice versa  Prior DVT is underlying cause in many cases w/2 major effects:  Destruction of valves in deep venous system causing valvular incompetence  Valves in perforator veins also damaged 2O to chronically elevated deep venous pressure o Inhibits normal transmission of blood from superficial to deep system  Ambulatory venous HTN  Interstitial fluid accumulation resulting in edema  Extravasation of plasma proteins & RBCs into subcutaneous tissues o Results in brawny induration & dark pigmentation due to hemosiderin deposits  Eventual  capillary blood flow w/tissue hypoxia – mild trauma may cause ulcer formation  Venous ulcers MC at medial malleolus – overlying incompetent perforator vein o Ulcer formation directly proportional to amount of swelling present o Clinical Presentation: 24

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 Pain  Aching or tightness of involved leg – often worse at end of day  Edema  Lower leg & relieved by elevation – opposite is true in arterial insufficiency  Skin  Stasis dermatitis, pruritus, hyperpigmentation, venous ulcers Diagnosis:  Doppler U/S  Most commonly used imaging technique  Ambulatory Venous Pressure (AVP)  Gold standard – but invasive & rarely done  Plethysmography  Noninvasive Treatment:  Conservative  Elastic compression stockings, leg elevation, avoid prolonged sitting/standing  Surgery  If conservative measures fail or recurrent/large ulcers  Ligation of perforators – in region of ulcer  Greater saphenous vein stripping  Venous bypass – if short segment obstruction  Ulcers  Wet-to-dry saline dressings, zinc-oxide wraps, antibiotics, debridement, unna boot  Split-thickness skin grafts – if unna venous boot (external compression stocking) fails

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Superficial Thrombophlebitis o Erythema, induration & tenderness along superficial vein – MC in greater saphenous system  MC at sites of IV infusion in upper extremities & usually ass. w/varicose veins in lower extremities o Etiology:  Infectious  Suppurative phlebitis – due to complication of IV cannulation  Inflammatory  Varicose veins, Buerger’s disease, SLE, trauma  Other  Polycythemia, thrombocytosis, occult malignancy (esp. pancreatic) o Clinical Presentation:  Pain w/cord-like swelling along course of involved vein  Induration, erythema & tenderness – corresponds to dilated & often thrombosed veins o Diagnosis  R/O associated DVT w/non-invasive tests o Treatment:  Conservative  Bed rest, limb elevation, heat, compression bandages, ASA  Suppurative thrombophlebitis  IV Antibiotics + I&D of involved vein o Complications  Simultaneous DVT (