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

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Course Highlights:

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.

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.

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.

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.

Acute Phase:

Immediate ↓ SVR.

↑ 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):

Adaptive hypertrophy.

Decompensation occurs when dilation exceeds contractility limits.

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).

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.

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).

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.

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).

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).

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.