Heart failure is a serious condition in which the heart cannot pump enough blood to meet the body’s needs, often causing dangerous fluid buildup and swelling. Although diuretics are the primary treatment to remove excess fluid, some patients show little or no improvement—a problem known as diuretic resistance. Understanding why some individuals respond well to treatment while others do not has remained an important clinical challenge. A new study now suggests that lymphatic flow in the legs could serve as a key indicator of treatment success in acute heart failure (AHF).

Researchers from Wroclaw Medical University (Wroclaw, Poland) and Duke University School of Medicine (Durham, NC, USA) conducted a clinical study to explore the role of the lymphatic system in fluid balance during heart failure treatment. The team used indocyanine green (ICG) lymphography, a near-infrared fluorescent imaging method, to visualize lymphatic flow in 65 hospitalized AHF patients. Three hours after standard administration of furosemide, a commonly used diuretic, imaging was performed to assess how quickly lymph fluid moved through the vessels in the lower limbs.

The study, published in the European Journal of Heart Failure, revealed a strong link between lymphatic efficiency and response to diuretic therapy. In 95% of patients who responded well, lymph flow extended above the ankle within 10 minutes, compared to just 73% of non-responders. Moreover, significant lymph flow of at least 10 cm was observed in 88% of responders versus only 45% of non-responders. The median lymph flow distance reached 50 cm in responders, but only 10 cm in those with poor outcomes, underscoring the predictive value of lymphatic performance.

The findings shed light on the lymphatic system’s overlooked role in maintaining fluid balance during heart failure therapy. When diuretics draw fluid from the bloodstream, the lymphatic system must replenish plasma volume by draining interstitial fluid back into circulation. If lymphatic transport is slow, the process stalls—similar to a pump running dry. The study also found that elevated aldosterone levels, a hormone promoting salt and water retention, correlated with slower lymph flow and weaker treatment responses.

According to the researchers, lymphatic flow could become a biomarker for tailoring diuretic therapy and optimizing decongestion strategies in acute heart failure. Future investigations will focus on developing non-invasive tools for real-time monitoring of lymphatic function. Such technologies could help clinicians assess fluid overload more precisely and adjust treatments for individual patients, improving outcomes and reducing hospitalization times.

“Our research shows a clear link between faster lymph flow and a stronger diuretic response in acute heart failure,” said Dr. Barbara Ponikowska, lead author of the study. “It suggests that lymphatic efficiency may be a missing component in understanding why some patients fail to respond to standard therapies.”

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