Cardiovascular Disease Fellow University of Texas Health Science Center at Houston Housotn, Texas, United States
Background: Myxedema coma (MC) is a rare and life-threatening manifestation of severe hypothyroidism. We report a case of severe undiagnosed hypothyroidism presenting with decompensated heart failure (HF) and refractory hypoxic respiratory failure. This case necessitated Extracorporeal Membrane Oxygenation (ECMO) with notable improvement.
Methods: A 38-year-old male with Class III obesity presented with progressive dyspnea, orthopnea, lower extremity swelling, and altered mental status. The patient had experienced HF symptoms for two years prior to presentation. On arrival, his vital signs were notable for hypothermia, bradycardia, bradypnea, and hypoxia. The patient underwent mechanical ventilation for acute respiratory failure; however, he remained persistently hypoxic.
Initial investigations revealed proBNP 623 pg/mL, lactate 1.5 mmol/L, normal liver function test, and an arterial blood gas showing pH 7.31 and pO2 41 mmHg. Transthoracic echocardiography (TTE) demonstrated preserved left ventricular ejection fraction (LVEF) of 55-60%, a mildly dilated right ventricle with reduced systolic function, and a large posterior pericardial effusion. Computed tomography (CT) showed diffuse consolidation, bilateral pleural effusion, and ascites. He was started on a diuretic drip, maximal ventilator support with sedation, paralytics, and inhaled nitric oxide. The patient’s thyroid-stimulating hormone (TSH) level was markedly elevated at 150 μIU/mL concerning for undiagnosed hypothyroidism. Endocrinology was consulted and clinical suspicion for myxedema coma prompted initiation of high-dose intravenous (IV) levothyroxine and stress-dose steroids.
Outcome: Despite these interventions, the patient remained severely hypoxic refractory to optimal mechanical ventilation and medical therapy. The ECMO team was activated, and a decision was made to proceed with veno-venous (VV) ECMO cannulation on day 1 of hospitalization. Bronchoalveolar lavage yielded normal respiratory flora with no bacterial or fungal pathogens. Transesophageal echocardiography (TEE) revealed a patent foramen ovale with a unidirectional (left-to-right) shunt. Right heart catheterization (RHC) revealed elevated biventricular filling pressures, post-capillary pulmonary hypertension and normal cardiac output/cardiac index. [CVP: 16 mmHg, RV: 39/16 mmHg, Mean PAP: 31 mmHg, PCWP: 24 mmHg, PVR: 0.84 Wood units, Cardiac index (CI): 2.9 L/min/m².] No evidence of shunt physiology. The patient was continued on IV levothyroxine and diuretics. Over subsequent days, the patient’s thyroid function and clinical status improved, allowing for ECMO weaning and decannulation on day 9, followed by successful extubation.
Conclusion: MC should be considered in patients presenting with unexplained cardiopulmonary failure. Early recognition and aggressive management of MC, including the potential use of advanced cardiopulmonary support such as ECMO, are critical in cases of refractory hypoxemia. This case underscores the importance of multidisciplinary care in managing the complexities of MC.
