The heart is not the only organ involved in blood propulsion. Researchers have long known that the aorta, the large vessel that exits the left heart ventricle and distributes oxygenated blood throughout the body, has elastic properties that cushion pressure variations. But a team of scientists has just demonstrated that its role is even more important. Using measurements taken with MRI scans on patients and laboratory experiments, they have demonstrated a pumping effect independent of the heart, produced by the stretching and relaxation of this large blood vessel.
Wave pumping
A study published in the Journal of the Royal Society Interface reveals that the aorta generates a pumping effect that could complement cardiac action through its successive stretching and relaxation. This phenomenon, called "wave pumping", is based on the aorta's ability to store energy during the contraction of the heart (systole) and to release it during its relaxation (diastole).
To test this hypothesis, the researchers were able to measure, with cardiac MRI, the longitudinal displacement of the aorta in 159 volunteers, and compare healthy individuals to patients suffering from heart failure. Their results suggest that this mechanism could play a role in the efficiency of blood circulation. In the laboratory, artificial models of the aorta were used to simulate this phenomenon, confirming that the stretching and relaxation of the aorta can generate a net blood flow, influenced by the frequency of the heartbeat and the rigidity of the aortic wall.
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A path to treat heart failure
While this aortic pumping naturally assists blood circulation, its effectiveness could be reduced in some patients, particularly those suffering from heart failure or aortic calcification. One avenue being considered would be to exploit this mechanism to lighten the load on the heart in people suffering fromheart failure, either by mechanical interventions or by drug treatments targeting the elasticity of the aorta. Currently, some antihypertensive drugs already modify arterial stiffness, but their effect on this wave pumping remains to be explored.
This phenomenon could also explain why some tired hearts manage to maintain sufficient blood circulation: the aorta would partly compensate for the loss of cardiac efficiency. Ultimately, a better understanding of this mechanism could pave the way for new therapeutic strategies to improve the management of cardiovascular diseases.
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