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.
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1. Core Definition & Hemodynamic Profile
Clinical Paradox: Congestive symptoms (pulmonary edema, JVD, peripheral edema) in the setting of a hyperdynamic, supranormal cardiac function.
Cardiac Index (CI): >4.0 L/min/m2.
Cardiac Output (CO): >8 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.
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 → eccentric remodeling → chamber dilation → 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.
Chronic Liver Disease (Cirrhosis):
Formation of “spider angiomata” and internal AV shunts.
Impaired clearance of endogenous vasodilators (e.g., Nitric Oxide).
Thiamine Deficiency (Wet Beriberi):
Accumulation of pyruvate/lactate → systemic vasodilation.
Histopathology: Vacuolation, myofiber hypertrophy, and interstitial edema.
Hypoxia/Hypercapnia-driven systemic vasodilation.
Concomitant pulmonary HTN (RV remodeling) but preserved/high LV output.
Others: Paget’s disease of bone (extensive micro-shunting), Carcinoid syndrome, Mitochondrial diseases, Acromegaly, Erythroderma.
4. Special Focus: Hemodialysis Access-Induced HOHF
Physiologic Phases of AVF Creation:
↑ Stroke volume and Heart Rate (SNS-mediated).
Endothelial shear stress → Nitric Oxide release → further arterial dilation.
Subacute Phase (Days to 2 Weeks):
RAAS-driven volume expansion.
↑ Right Atrial, Pulmonary Artery, and LV End-Diastolic Pressures (LVEDP).
Natriuretic peptide surge (BNP/ANP) peaks around Day 10.
Chronic Phase (Weeks to Months):
Decompensation occurs when dilation exceeds contractility limits.
5. Point-of-Care Physical Exam & Maneuvers
Nicoladoni-Branham Sign (Pathognomonic for Shunt-driven HOHF):
Maneuver: Manually compress the AVF (or inflate cuff to >50 mmHg above SBP) for 30 seconds.
Positive Result: Reflexive bradycardia or a transient rise in systemic BP.
Significance: Confirms the shunt is a major contributor to the cardiac workload.
Peripheral Pulse Assessment:
Water Hammer Pulses: Rapid upstroke and collapse.
Quincke’s Pulse: Visible capillary pulsations in the nail beds.
Traube’s Sign: “Pistol-shot” sounds auscultated over the femoral arteries.
Volume Status: Rales, S3 gallop, peripheral edema (standard HF signs).
6. Diagnostic Workup (Technical Targets)
POCUS / Echocardiography:
Left Ventricle: Hyperdynamic function; EF typically >60%.
Left Atrium: Significant dilation (Left Atrial Volume Index >34 mL/m2; Case study noted 72 mL/m2).
IVC: Plethoric with minimal respiratory variation.
Doppler: High flow velocities across the AV access if applicable.
Laboratory Evaluation:
BNP/NT-proBNP: Often markedly elevated (e.g., >70,000 in severe cases), though mean values in literature hover around 700–800 pg/mL.
Hematology: CBC to evaluate for severe anemia (trigger for HOHF if Hgb<7–8 g/dL) or myeloproliferative markers.
Endocrine/Metabolic: TSH (Thyrotoxicosis), Serum Thiamine (Beriberi), LFTs (Cirrhosis).
7. Management Strategy: A Stepwise Approach
Phase 1: Immediate Stabilization (Volume Offloading)
Diuresis: Aggressive IV loop diuretics (Bumetanide/Furosemide).
Ultrafiltration: Preferred in ESRD patients failing to respond to dialysis or with refractory congestion.
Vasodilator Caution: Avoid aggressive Nitroglycerin or ACE-inhibitors initially.
Rationale: Baseline SVR is already pathologically low; further reduction may precipitate profound hypotension/circulatory collapse.
Phase 2: Targeted Therapy (Etiology Specific)
Anemia: Transfuse to goal Hgb>7–8 g/dL to reduce demand.
Beriberi: High-dose IV Thiamine (100–500 mg).
Thyrotoxicosis: Beta-blockers (Propranolol) + Antithyroid meds (PTU/Methimazole).
Phase 3: Surgical/Interventional Salvage (Refractory AVF Cases)
Closure of Accessory Sites: If multiple fistulas exist, close the non-dominant/unused sites.
Flow Reduction (Banding): Surgical narrowing of the fistula to target flow <600 mL/min.
RUDI Procedure: Revision Using Distal Inflow (moving inflow to a smaller, more distal artery).
Ligation: Complete closure of the AVF.
Note: Requires bridge to Tunneled Dialysis Catheter or AV graft (higher resistance than fistulas).
8. Key Clinical Takeaways
The “Normal EF” Trap: Do not be reassured by an EF of 55–65%; in the context of pulmonary edema and high CO, this is potentially HOHF.
Pulse Pressure: Look for a wide pulse pressure (e.g., 180/60) as a marker of low SVR.
ESRD Logic: If an ESRD patient is “wet” immediately after HD, the problem is likely flow (AVF), not just fluid.
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