As heart patients survive ever more complex surgeries, they are often surprised by how tough it can be to bounce back after the operation.

While recovery can be a long slog after any major surgery, invasive procedures on the body’s most vital organ can be especially traumatic. During heart surgery, the body’s natural inflammatory response to injury can be dramatically amplified, leading to complications such as altered liver and kidney function. Patients may emerge not only physically frail, but also have trouble with brain function due to heavy anesthesia.

As much as 40 percent of patients suffer from depression after cardiac surgery, research shows. And in older patients, psychological and social issues such as isolation and a lack of a strong support network can also limit recovery after the stress of cardiac surgery, according to a study published in April in the journal Experimental Gerontology.

“Cardiac surgery is not just a physical thing, but a big stressor on cognitive function, psychological health, and overall health, and it distresses your social and personal environment as well,” says study co-author James L. Rudolph, associate professor at Brown University’s medical school and director of the Center of Innovation in Long-Term Services and Supports at the Providence VA Medical Center, in Rhode Island. “Medicine doesn’t do a good job of taking some of those things into account.”

Surgeons typically discuss with patients a detailed list of potential complications and recovery issues, including depression, but often patients and their families are so nervous they may not take it all in, says Robbin G. Cohen, associate professor of cardiothoracic surgery at University of Southern California Keck School of Medicine.