IBHRE REVIEW EXAM ACTUAL 2025/2026 QUESTIONS AND 100% CORRECT ANSWERS

BHRE REVIEW EXAM ACTUAL 2025/2026 QUESTIONS AND 100% CORRECT ANSWERS AV Node Reentry Tachycardia (AVNRT) - Answer -- accounts for ~60% of arrhythmias presenting as SVT or paroxysmal atrial tachycardia (PAT) - affects all age groups and genders equally - no correlation with heart disease - heart rate 150-250 bpm, palpitations, light-headedness, near-syncope, narrow QRS complex rheobase - Answer -lowest point on a strength duration curve at an infinitely long pulse duration; for cardiac pacing, the rheobase is usually reached between 1-2ms chronaxie time - Answer -pulse width at twice the rheobase value approximates most efficient stimulation pulse duration action potential - Answer -the cellular characteristics of depolarization and repolarization 5 phases (0-4) phase 0 - Answer -depolarization, rapid Na+ channels open, resting potential (-90mV) to ~0mVphase 1 - Answer -early repolarization; peak of depolarization phase 2 - Answer -the "plateau phase", mediated by slow Ca2+ channels, disrupts and delays the repolarization started in phase 1 and prolongs refractory phase 3 - Answer -end of repolarization phase 4 - Answer -resting phase, leaking of K+ and Na+ silicone rubber insulation - Answer -pros: - can be easily repaired - flexible - proven performance history - easy to produce cons: - high friction coefficient - absorbs lipids - more thrombogenic & fibrotic - cuts & tears easily - large diameter (comparatively) polyurethane 80A (pellethane) - Answer -pros: - relatively nonthrombogenic- thinner walls, flexible - tougher, abrasion resistant - resists cutting - low friction coefficient cons: - adverse history - longevity 7 years - not repairable - very process-dependent recalled in 1995 by the FDA for inner insulation failure due to metal ion oxidation (MIO) polyurethane 55D (pellethane) - Answer -pros: - proven history - longevity 12 years - easy to process - very tear-resistant and tough - thinner walls