How Does a Heart-Lung Machine Work?

A heart-lung machine takes over the work of the heart and lungs during open cardiac surgery. It pumps oxygenated blood through the body while the surgeon operates on a stopped, motionless heart. Blood is drained from the patient, passes through an oxygenator that adds oxygen and removes carbon dioxide, then gets returned to the circulation. The machine is essential for procedures where the heart needs to be still and bloodless to operate on safely.

According to Dr. Vishal Khullar, a Mumbai-based specialist in cardiac surgery, The heart-lung machine is what makes complex cardiac surgery possible. It buys the surgeon a still, bloodless field, while keeping the rest of the body alive and oxygenated.

The patient gets connected through cannulas, which are tubes placed in the major blood vessels around the heart.

Venous drainage: A cannula is placed in the right atrium or vena cava. Blood that would normally enter the heart drains into the machine instead.

Oxygenation: The drained blood passes through the oxygenator, picking up oxygen and releasing carbon dioxide, just as the lungs would.

Arterial return: Oxygen-rich blood gets pumped back into the aorta through another cannula, supplying the body normally.

Cardioplegia: A potassium-rich solution is delivered to the heart to stop it from beating, so the surgeon can operate on a motionless target.

The heart-lung machine plays a central role in most open-heart procedures, particularly in complex cases where the heart needs to be still for an extended period.

Dr. Vishal Khullar is the Director of Cardiovascular and Thoracic Surgery, Heart & Lung Transplant at Fortis Hospital Mulund and Fortis S L Raheja Hospital, Mumbai. Over 30 years in the field. Training at Cleveland Clinic and Mayo Clinic in the USA. Thousands of cardiac procedures completed with the support of advanced perfusion teams and heart-lung machine setups.

His operating teams include experienced perfusionists who manage the heart-lung machine throughout surgery. Patients benefit from coordinated care between the surgeon, anaesthetist, and perfusion team, which keeps the procedure safe even when it runs long.

1. MedlinePlus (NIH) – Heart Bypass Surgery
2. American Heart Association – Heart Surgery and Recovery Resources