Causes of High Output Heart Failure:
– Obesity (most common ~ 31%)
– Systemic AV shunts (22.5%)
– Hepatic disease (22.5%)
– Lung disease (i.e. COPD ~ 16%)
– Myeloproliferative disorders (multiple myeloma, myelofibrosis)
– Sepsis/Fever
– Hyperthyroidism
– Anemia

Hyperthyroidism
Presentation:
Increased thyroid hormone → increased metabolism → decreased SVR → increased cardiac output → increased contractility of heart muscle → increased myocardial oxygen demand/consumption

Physical Exam:
– tachycardia / atrial fibrillation
– hyperdynamic precordium
– systolic hypertension with widened pulse pressure
– brisk carotid/peripheral arterial pulsations
– loud first heart sound
– fine tremor
– warm moist skin
– exophatalmos (occurs in 20-25% of Graves patients)

– pretibial myxedema

Treatment:
– return patient to euthyroid state with antithyroid medication or RAI
– caution BB use – can reduce myocardial contractility in patients with impaired LVSF

Radioiondine Uptake Scan Interpretation:

Normal/Elevated Uptake:
[Autoimmune] – Graves disease, Hashimotos thyroiditis
[Autonomous Thyroid Tissue] – Toxic adenoma, toxic multinodular goiter
[TSH-mediated] – pituitary tumor

Low/Absent Uptake:
[Thyroiditis] – de Quervain’s thyroiditis, radiation thyroiditis, amiodarone thyroiditis
[Exogenous Thyroid Hormone] – excessive replacement, factitious hyperthyroidism
[Ectopic Hyperthyroidism] – Struma ovarii, metastatic follicular thyroid cancer