Core EM - Emergency Medicine Podcast podcast

Episode 221: High-Output Heart Failure

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We discuss the diagnosis and treatment of one of EM's paradoxes: High-Output Heart Failure.

Hosts:
Nicolas Gonzalez, MD
Brian Gilberti, MD

https://media.blubrry.com/coreem/content.blubrry.com/coreem/HOHF.mp3 Download Leave a Comment Tags: Cardiology

Show Notes

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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.

  • Hemodynamic Criteria:

    • 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.

  • 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 → 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.

  • Chronic Lung Disease:

    • 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:

  1. Acute Phase:

    1. Immediate ↓ SVR.

    2. ↑ Stroke volume and Heart Rate (SNS-mediated).

    3. Endothelial shear stress → Nitric Oxide release → further arterial dilation.

  2. Subacute Phase (Days to 2 Weeks):

    1. RAAS-driven volume expansion.

    2. ↑ Right Atrial, Pulmonary Artery, and LV End-Diastolic Pressures (LVEDP).

    3. Natriuretic peptide surge (BNP/ANP) peaks around Day 10.

  3. Chronic Phase (Weeks to Months):

    1. Adaptive hypertrophy.

    2. 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)

  1. Closure of Accessory Sites: If multiple fistulas exist, close the non-dominant/unused sites.

  2. Flow Reduction (Banding): Surgical narrowing of the fistula to target flow <600 mL/min.

  3. RUDI Procedure: Revision Using Distal Inflow (moving inflow to a smaller, more distal artery).

  4. 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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