Show Notes

Core EM Modular CME Course

Maximize your commute with the new Core EM Modular CME Course, featuring the most essential content distilled from our top-rated podcast episodes. This course offers 12 audio-based modules packed with pearls! Information and link below.

Course Highlights:

Credit: 12.5 AMA PRA Category 1 Credits™
Curriculum: Comprehensive coverage of Core Emergency Medicine, with 12 modules spanning from Critical Care to Pediatrics.
Cost:
- Free for NYU Learners
- $250 for Non-NYU Learners

Click Here to Register and Begin Module 1

1. Core Definition & Hemodynamic Profile

Clinical Paradox: Congestive symptoms (pulmonary edema, JVD, peripheral edema) in the setting of a hyperdynamic, supranormal cardiac function.
Hemodynamic Criteria:
- Cardiac Index (CI): $> 4.0\text{ L/min/m}^2$ .
- Cardiac Output (CO): $> 8\text{ L/min}$ .
- Systemic Vascular Resistance (SVR): Pathologically low (vasodilated or shunted state).
The “Warm” Phenotype: Unlike standard HFrEF/HFpEF (often “Cold and Wet”), HOHF presents as “Warm and Wet” due to low SVR and bounding pulses.

2. Pathophysiology: The Hemodynamic Paradox

Primary Insult: Decreased SVR (either via peripheral vasodilation or arteriovenous shunting).
Effective Arterial Blood Volume: Paradoxically low despite high total CO.
Neurohormonal Cascade:
- Activation of Renin-Angiotensin-Aldosterone System (RAAS).
- Increased Sympathetic Nervous System tone.
- Increased Antidiuretic Hormone (ADH) secretion.
Resultant State: Avid renal salt and water retention leading to massive plasma volume expansion.
Cardiac Response: Chronic volume overload $\rightarrow$ eccentric remodeling $\rightarrow$ chamber dilation $\rightarrow$ eventual secondary myocardial failure/dilated cardiomyopathy.

3. Differential Diagnosis: Etiological “Buckets”

Category A: Increased Metabolic Demand (Systemic)

Hyperthyroidism/Thyrotoxicosis:
- Direct T3 effects: increased chronotropy/inotropy.
- Indirect effects: metabolic byproduct accumulation causing peripheral vasodilation.
Myeloproliferative Disorders:
- High cell turnover and increased oxygen consumption drive compensatory CO increase.
Sepsis (Hyperdynamic Phase):
- Cytokine-mediated global vasodilation.
- Note: Often transient; may transition to sepsis-induced myocardial depression.

Category B: Peripheral Vascular Effects (Shunting/Vasodilation)

Arteriovenous Fistulas (AVF) / Malformations (AVM):
- Most Common Cause: Iatrogenic AVF for Hemodialysis (ESRD population).
- Bypasses high-resistance capillary beds, dumping arterial blood directly into venous circulation.
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