Researchers at Karolinska Institutet and KTH Royal Institute of Technology in Sweden have contributed to a recent discovery that the heart is filled with the aid of hydraulic forces, the same as those involved in hydraulic brakes in cars.

The findings, which were presented in the journal Scientific Reports, open avenues for completely new approaches to the treatment of heart failure.

Hydraulic forces that help the heart’s chambers to fill with blood arise as a natural consequence of the fact that the atrium is smaller than the ventricle.

Using cardiovascular magnetic resonance (CMR) imaging to measure the size of both chambers during diastole in healthy participants, the researchers found that the atrium is smaller effectively throughout the filling process.

“Although this might seem simple and obvious, the impact of the hydraulic force on the heart’s filling pattern has been overlooked,” says Dr. Martin Ugander, a physician and associate professor who heads a research group in clinical physiology at Karolinska Institutet. “Our observation is exciting since it can lead to new types of therapies for heart failure involving trying to reduce the size of the atrium.”

Many patients with heart failure have disorders of the filling phase, often in combination with an enlarged atrium. If the atrium gets larger in proportion to the ventricle, it reduces the hydraulic force and thus the heart’s ability to be filled with blood.

“Much of the focus has been on the ventricular function in heart failure patients,” says Dr. Elira Maksuti at KTH’s Medical Imaging Unit and recent PhD from KI’s and KTH’s joint doctoral programme in medical technology. “We think it can be an important part of diagnosis and treatment to measure both the atrium and ventricle to find out their relative dimensions.”

The study was the result of a multidisciplinary collaboration between Karolinska Institutet, KTH and Lund University in Sweden and Washington University in St. Louis, USA and was financed with grants from the Swedish Research Council, the Swedish Heart–Lung Foundation, Stockholm County Council and Karolinska Institutet.