Cardiac Anatomy, Human Anatomy, USMLE Step 1 - Full Vignette with Extended Explanations скачать в хорошем качестве

Cardiac Anatomy, Human Anatomy, USMLE Step 1 - Full Vignette with Extended Explanations

A 75-year-old woman with known hypertrophic cardiomyopathy, genetic predisposition, and multiple comorbidities presents to a rural emergency department during a blackout with sudden palpitations, lightheadedness, and near-syncope. With limited resources and only battery-backed ultrasound and labs available, how should the care team determine if dynamic LV outflow tract obstruction plays a role in her current tachyarrhythmic episode? Which clinical clues and bedside tools will help guide urgent management decisions in this setting? VIDEO INFO Category: Cardiac Anatomy, Human Anatomy, USMLE Step 1 Difficulty: Hard - Advanced level - Challenges experienced practitioners Question Type: Diagnostic Step Case Type: Resource Limited Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h... QUESTION A 75-year-old woman with hypertrophic cardiomyopathy (genotype positive for a pathogenic MYH7 variant), cervical spondylotic myelopathy, and a history of deep venous thrombosis with antithrombin III deficiency presents to a critical-access emergency department during a regional power outage after sudden palpitations, lightheadedness, and near-syncope at home.... OPTIONS A. Acquire a focused bedside transthoracic echocardiogram (parasternal long-axis and apical views) with continuous-wave Doppler across the LVOT to document SAM and quantify a dynamic LVOT gradient-at rest and with Valsalva-to guide immediate physiology-tailored therapy. B. Perform a limited bedside transthoracic echocardiogram restricted to 2D imaging without Doppler because of the outage, using murmur intensity alone to infer dynamic LVOT obstruction severity before choosing vasoactive therapy. C. Arrange a transesophageal echocardiogram after transfer when services resume, because only TEE can definitively visualize mitral-septal contact and quantify obstruction accurately in obstructive hypertrophic cardiomyopathy. D. Rely solely on a 12-lead ECG when power returns to distinguish AV nodal reentry from atrial flutter and defer any imaging assessment of outflow anatomy until elective follow-up after rhythm control. CORRECT ANSWER A. Acquire a focused bedside transthoracic echocardiogram (parasternal long-axis and apical views) with continuous-wave Doppler across the LVOT to document SAM and quantify a dynamic LVOT gradient-at rest and with Valsalva-to guide immediate physiology-tailored therapy. EXPLANATION In obstructive hypertrophic cardiomyopathy, clinical decisions during tachyarrhythmia hinge on whether dynamic LV outflow tract obstruction is present and to what degree. With the power outage limiting advanced imaging but a continuous-wave Doppler-capable ultrasound cart at the bedside, the most informative next step is a focused transthoracic echocardiogram with continuous-wave Doppler aligned through the LVOT to document systolic anterior motion and quantify the instantaneous peak gradient at rest and during Valsalva. This directly answers the anatomy-dependent physiology question and guides immediate therapy, favoring preload and afterload augmentation and avoidance of inotropes or vasodilators if severe dynamic obstruction is confirmed. This approach is consistent with the 2020 AHA/ACC hypertrophic cardiomyopathy guideline prioritizing Doppler quantification to guide acute management decisions. The alternative strategies each miss the critical physiologic measurement.... --------------------------------------------------- Our cases and questions come from the https://EndlessMedical.Academy quiz engine - multi-model platform. Each question and explanation is forged by consensus between multiple top AI models (GPT, Claude, Grok, etc.), with automated web searches for the latest research and verified references. Calculations (e.g. eGFR, dosages) are checked via code execution to eliminate errors, and all references are reviewed by several AIs to minimize hallucinations. Important note: This material is entirely AI-generated and has not been verified by human experts; despite stringent consensus checks, perfect accuracy cannot be guaranteed. Exercise caution - always corroborate the content with trusted references or qualified professionals, and never apply information from this book to patient care or clinical decisions without independent verification. Clinicians already rely on AI and online tools - myself included - so treat this book as an additional focused aid, not a replacement for proper medical education. Visit https://endlessmedical.academy for more AI-supported resources and cases. This material can not be treated as medical advice. May contain errors. ---------------------------------------------------