Cardiovascular Pathology, Pathology, USMLE Step 1 - Full Vignette with Extended Explanations скачать в хорошем качестве

Cardiovascular Pathology, Pathology, USMLE Step 1 - Full Vignette with Extended Explanations

A 43-year-old man with a complex medical history including chronic lung disease, past stroke, and fainting spells presents with intermittent dizziness and two brief loss-of-consciousness episodes. He describes prodromal symptoms, normal orthostatic vitals, and reproducible symptoms on tilt table testing. How should you approach the diagnostic evaluation in patients with recurrent syncope and these provocative test findings? What clinical clues can guide your differential diagnosis? VIDEO INFO Category: Cardiovascular Pathology, Pathology, USMLE Step 1 Difficulty: Easy - Basic level - Suitable for medical students Question Type: Diagnosis - Identify conditions based on clinical presentation Case Type: Complicated Condition Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h... QUESTION A 43-year-old man reports several months of intermittent dizziness and two brief faints. He works in construction and quit smoking last year (15 pack-years). Past conditions include a remote stroke without deficit, idiopathic pulmonary fibrosis, COPD, and nonalcoholic steatohepatitis. Medications are tiotropium daily, albuterol as needed, pramipexole 0.125 mg nightly, and omeprazole; he also takes an over-the-counter probiotic.... OPTIONS A. Vasovagal (neurally mediated) syncope with a mixed cardioinhibitory and vasodepressor response provoked on tilt testing. B. Neurogenic orthostatic hypotension from autonomic failure after prior stroke causing a sustained blood pressure fall on standing without adequate heart rate compensation. C. Postural orthostatic tachycardia syndrome with exaggerated sinus tachycardia and preserved blood pressure on upright posture. D. Primary arrhythmic syncope from paroxysmal atrial fibrillation despite a normal baseline electrocardiogram. CORRECT ANSWER A. Vasovagal (neurally mediated) syncope with a mixed cardioinhibitory and vasodepressor response provoked on tilt testing. EXPLANATION The tilt-table result reproducing symptoms with a fall in blood pressure and a drop in heart rate after nitroglycerin strongly supports vasovagal (neurally mediated) syncope with a mixed cardioinhibitory and vasodepressor response. The patient s prodrome of nausea, warmth, and tunnel vision, normal resting ECG, normal orthostatic vitals in clinic, and absence of structural heart disease on exam further favor vasovagal syncope. Mixed responses show simultaneous vagally mediated bradycardia and sympathetic withdrawal-mediated vasodilation, which together cause transient cerebral hypoperfusion and syncope. Neurogenic orthostatic hypotension presents with a sustained blood pressure fall on standing without appropriate heart rate compensation, usually within 3 minutes of upright posture, and would show abnormal orthostatic vitals rather than a tilt-provoked mixed reflex response. Postural orthostatic tachycardia syndrome requires an exaggerated sinus tachycardia upon standing with relatively preserved blood pressure, not a bradycardic response. Primary arrhythmic syncope from paroxysmal atrial fibrillation is unlikely with a normal baseline ECG, prodromal autonomic symptoms, and tilt-provoked reflex physiology. In summary, the correct answer is vasovagal (neurally mediated) syncope with a mixed cardioinhibitory and vasodepressor response on tilt testing. Key teaching points: A typical prodrome plus tilt-provoked hypotension and bradycardia supports vasovagal syncope. Normal orthostatics and absence of excessive upright tachycardia argue against neurogenic orthostatic hypotension and POTS, respectively. --------------------------------------------------- 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. ---------------------------------------------------