Case Presentation: A 60-year-old male with cirrhosis secondary to metabolic and alcoholic-associated liver disease (MetALD) presented to the emergency department after a fall. At time of arrival, he was incidentally found to have an oxygen saturation of 70% on room air without dyspnea. Oxygen saturation improved to 91% on 8 L/min via nasal cannula but declined to 80% when supine, despite clinical euvolemia. Transthoracic echocardiogram (TTE) with agitated saline demonstrated normal cardiac function (EF 55–60%) and a right-to-left shunt consistent with an atrial septal defect or patent foramen ovale, indicated by left atrium bubble appearance within three cardiac cycles. Computed tomography angiography (CTA) of the chest was obtained and ruled out other etiologies of hypoxia. Comprehensive right and left heart catheterization with intracardiac echocardiography, including color doppler and bubble study, demonstrated no evidence of intracardiac shunt, elevated pulmonary pressures, or other cardiac etiology for hypoxia. Given strong clinical suspicion for hepatopulmonary syndrome (HPS), a 99mTc-MAA perfusion lung scan was obtained. This demonstrated 32.1% extrapulmonary activity, confirming a non-cardiac right-to-left shunt. A room air arterial blood gas displayed a PaO2 of 58 mmHg and an A-a gradient of 64.2 mmHg. HPS was officially diagnosed by outpatient pulmonology based on history of cirrhosis, elevated A-a gradient, and presence of a non-cardiac shunt on imaging. The patient continued to follow with hepatology for consideration of liver transplant.
Discussion: HPS is a potentially reversible cause of hypoxemia in chronic liver disease. Five-year survival is markedly reduced without liver transplantation (23% vs. 76% with transplant), highlighting the importance of early recognition and referral [1]. This is a high-mortality disease, and hospitalists should not stop at a presumed intracardiac shunt without corroborative testing if HPS is on the differential and other cardiac and pulmonary etiology have been ruled out. Typically, bubbles appearing in the left atrium before the fourth cardiac cycle are indicative of intracardiac shunting, whereas appearance after the third cardiac cycle suggests intrapulmonary shunting. Our case challenges this notion since the TTE revealed prompt arrival of bubbles before the third cardiac cycle, but the lung perfusion scan was consistent with intrapulmonary shunting. Studies have identified early left atrium bubble arrival in severe cases of HPS [2]. HPS remains frequently underrecognized in hospital settings, often due to asymptomatic presentations; however, prevalence studies estimate HPS to exist in one-fourth of cirrhotic patients [3]. Given the high morbidity and mortality of this disease, as well as its asymptomatic nature, as in our patient’s case, hospitalists should maintain a high index of suspicion for HPS in hypoxemic cirrhotic patients. Failure to consider further workup in patients with cirrhosis and otherwise unexplained hypoxemia may result in a detrimental missed diagnosis of HPS.
Conclusions: Oftentimes, hospitalists are the central providers able to encourage consultants to pursue definitive testing when misleading information is present. Further research is necessary to elucidate the prevalence of false positive intracardiac bubble studies in patients with HPS. Hospitalists play a crucial role in synthesizing conflicting data, advocating for diagnostic clarity, and ensuring high mortality-diseases are not missed.
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