Explain how multiple wandering re-entrance circuits can result in atrial fibrillation. (SIGS 6.1a)
Wandering re-entrance circuits able to continuously find excitable tissue--> depolarization of atria--> fibrillatory contractions in atrial myocytes
15
Describe the mechanism(s) of action of diltiazem and its effect on cardiac conductivity (SIGS 6.1a)
MOA: inhibits inflow Ca2+ ions into cardiac smooth muscle (SM) during depolarization; Decr. intracellular Ca2+ --> incr. SM relaxation/vasodilation--> decr. BP
15
Describe the role of INR monitoring in anticoagulation therapy and explain the need for bridge therapy with warfarin. (SIGS 6.1a)
monitor coagulability (maintain optimal level- not too low or too high); Bridge therapy for warfarin due to taking several days to achieve therapeutic effects
15
Explain the effects of electrolyte imbalance on cardiac conduction and the impact erythromycin would have. (SIGS 6.1a)
alter depol/ pol/ repol; macrolide antibiotic w/ AE prolonged QT intv. d/t blockage of K+ channels--> delays phase 3 repolariz.--> more intracellular K+--> EADs
15
Identify the AV blocks, rhythm, and atrial and ventricular rates on the ECGs.(SIGS 6.1b)
1st: Prolonged PR; 2nd Type I: Prolong PR, drop P; 2nd Type II: Drop QRS w/out PR prolong; 3rd: No association between P and QRS constant R-R interval
15
Distinguish between cardiac conduction blocks (sinus block; bundle branch block; hemiblock) on an EKG. (SIGS 6.1b)
A: Sinus block; B: LBBB; C: RBBB; D: Hemi/fascicular (Left posterior hemiblock is associated with a frontal plane QRS axis more positive than +120°)
15
Explain how atropine alters conduction. (SIGS 6.1b)
Describe integrative approaches to atrial fibrillation. (SIGS 6.1b)
Med. diet, stress reduction, no alcohol or caffeine, diet high in magnesium, fish oil, CoQ10
15
Discuss the use of ACE-inhibitors and beta-blockers to slow or reverse cardiac remodeling. (Sigs Case 6.2a)
ACE-inh.: allows heart to get more blood flow & decrease LV filing & decreases peripheral resistance; BB: decreases demand on heart and lowers BP
15
What is the MOA of Colchicine and how does it relate to the management of pericarditis?(Sigs Case 6.2a)
used as a theoretical anti-inflamm. agent; inhibits IL-1 from cascading, interferes w/ NFK-B; binds to microtubular tubulin in neutrophils-> inhibits mitosis
15
Describe the pathogenesis of coxsackievirus type B and how it relates to viral myocarditis. (Sigs Case 6.2a)
GI tract (stable at low gI pH)→infects mucosal epithelial cells→viremia→infects + lyse heart/pleural surfaces
15
Define the characteristic histopathologic features of acute viral myocarditis.(Sigs Case 6.2a)
lymphohistocytic; infiltration of lymphocytes that bring about T lymphocytes; myocyte is elongated w/ nuclei
15
Discuss the effects of alcohol on the heart. How can alcoholism lead to thiamine deficiency and exacerbate DCM? (SIGS 6.2b)