The heart is a machine that functions best when all its parts work together well. There are no stars on the cardiac team, but the light often shines most brightly on one.
The left ventricle, which pumps life-sustaining blood to the body, generally gets the greatest share of attention from cardiologists, said Dr. William Cornwell, an advanced heart failure and transplant cardiology specialist with the UCHealth Heart Failure Clinic – Anschutz Medical Campus.
“The left ventricle is the workhorse of the heart,” Cornwell said. “For that reason, there has been a great deal of interest in it.” That focus has spurred important medical advances, notably left ventricular assist devices (LVADs), which mechanically support the pumping power of weakened left ventricles in heart failure patients.
But the left ventricle doesn’t operate independently. It relies on receiving an adequate supply of oxygenated blood. That’s the responsibility of the right ventricle, which delivers blood to the lungs. A poorly functioning right ventricle makes it difficult for the left side of the heart to function appropriately, even among heart failure patients who are supported by an LVAD.
“We’ve traditionally been more concerned with what is happening on the left side of the heart, but what we have found is that the right side also affects outcomes significantly when it becomes dysfunctional,” Cornwell said. That recognition has led to “renewed interest” in the workings of the right ventricle, he added.
Heart failure research
Cornwell is among those who are interested. He leads a study at UCHealth – University of Colorado Hospital on the Anschutz Medical Campus that aims to increase understanding of how the right ventricle works among individuals across the spectrum of health and disease, from elite athletes to patients with advanced heart failure and those supported by LVADs. Using advanced technology, Cornwell and his colleagues view the right ventricle “from the inside” and measure its output, pressure and ability to contract during periods of exercise and rest.
The study divides heart failure participants into two groups based on their ejection fraction, a key measure of the left ventricle’s pumping power. Both stand at less than the healthy standard of at least 50%. The third group includes endurance athletes. They merit attention, Cornwell said, because evidence suggests that the stress of high-intensity sports may affect the right side of the heart more than the left.
The tools include conductance catheters, inserted into the right ventricle, that measure both pressure and volume in the chamber as participants exercise. Meanwhile, computers analyze information about how the organs, blood vessels and muscles function during the work. The real-time look is important, Cornwell said, because heart failure patients generally experience debilitating physical symptoms while they are upright and moving around, not when they are lying flat on a table, which is how providers often assess them.
Amping up the activity
For participants in the heart failure groups, the close view comes during periods of exercise of varying intensity. Cornwell and his colleagues want to use the data they gather to help people live more productively with their disease.
Patients come to the Heart Failure Clinic, Cornwell said, complaining of fatigue or shortness of breath during ordinary tasks, like cleaning the house or walking through the grocery store. That’s a major problem that needs to be addressed.
“We go to great lengths to understand what happens to the heart during routine activities of daily living,” Cornwell said. “To understand what is limiting them, you have to exercise people at different workloads that simulate those levels of intensity while the catheters are in place. A supine resting assessment does not adequately portray how the heart responds during activity.”
During the study session, researchers gradually increase the exercise workload to find a patient’s physical limits. The cumulative physiological findings could help patients find more effective ways to manage their condition and spur research into new treatments for the disease.
“There are also lessons to be learned that could help other patients,” Cornwell said. For example, new data could improve understanding of pulmonary hypertension, a disease that results from a dangerous increase in pressure inside of the lungs.
Assessing the athletes during heart failure study
Athlete participants go through a very different regimen. The 13-hour study includes a before-and-after cardiac MRI. With the catheter inserted in the heart, the athlete mounts an exercise bike and pedals 180 kilometers – the equivalent of a triathlon. (Restrictions imposed by the COVID-19 pandemic have thus far limited the number of enrolled athletes to just two, But Cornwell said he hopes to restart recruitment for his group soon.)
The portion of the trial for athletes is a first, Cornwell said, because previous studies were done non-invasively, with pictures of the heart taken before and after exercise. “No one has done it during endurance exercise,” he said.
Endurance athletes obviously have no problems handling a shopping jaunt or a garage-cleaning stint. Their hearts are larger and stronger than most, but prolonged exercise puts unusual pressure on the thin-walled right ventricle, which can make it harder to get blood to the lungs.
The study could help providers and athletes “understand the limits of human performance and how you can increase it,” Cornwell said. For example, athletes might alter their training schedules based on their knowledge of how exercise levels affect the right ventricle.
The next step along a research path
The current trial extends Cornwell’s ongoing quest to improve understanding of how the right side of the heart functions. He co-authored a February 2021 article in Journal of Heart and Lung Transplantation that examined right-side function in patients with LVADs. The study showed that even with lifesaving LVADs, patients still had severely diminished physical capacity, particularly during exercise. Many also had right-side heart problems.
Jim Walsh participated in and benefited from that study. Walsh, 72, of Denver, battled a bevy of heart problems over more than two decades. The trouble began in 1995 with congestive heart failure caused by an aneurysm in the main stem of his coronary artery. A pair of open-heart surgeries repaired the aneurysm, but over time his left ventricle steadily weakened.
The left-side deterioration weakened the right side of Walsh’s heart. He developed pulmonary hypertension, which made him too great a risk for a heart transplant. In 2016, cardiothoracic surgeon Dr. Joseph Cleveland implanted Walsh with an LVAD at University of Colorado Hospital.
The LVAD kept Walsh alive, but he continued to labor with physical exertion, and the device irritated the bottom of his heart. That caused frequent arrhythmias that required defibrillation. Walsh’s pulmonary hypertension also persisted.
Through the LVAD surgery and beyond, Cornwell helped to manage Walsh’s care, including his pulmonary hypertension and enrolled him in the now-published study. Walsh went to Cornwell’s exercise lab, where he had a catheter inserted through an artery in his wrist. The study team took measurements of his pulse, blood pressure and blood gases at rest, then he donned a facemask and exercised to his physical limit.
A clearer cardiac picture
The resulting data provided a more precise clinical picture of Walsh’s cardiac capacity. In addition, Walsh said, Cornwell “was kind enough to share with me what his findings were and how my individual measurements compared to the overall results.”
The trial also spurred him to increase his exercise. Data and determination “melded,” Walsh said, and helped Cornwell build the case for a transplant. Walsh received a new heart in 2019.
Now a survivor of four open-heart surgeries, Walsh is quick to credit improving medical technology and especially the people who use it in the service of patients.
The promise of research
“None of the incredible scientific advancements that saved my life on each of those occasions would have been possible without the talent of people like Dr. Cornwell,” Walsh said. He stressed the importance of Cornwell’s commitment to his care, through the LVAD implant, treatment for his pulmonary hypertension, the heart transplant and beyond.
“He fought like hell for me,” Walsh said.
The battle paid off for Walsh in a very personal way this year when he watched with his wife Basha as their daughter Shaina graduated from high school. Just four years earlier, Walsh wasn’t sure he would have the experience. Shaina is now a freshman at Fordham University in New York.
Walsh also stressed that medical advances rely on the willingness of people like himself to participate in clinical trials. He sees his contribution to Cornwell’s studies of the right ventricle in a greater context of service.
“I’m very happy to be alive and walking in the footsteps of others who participated in clinical trials before me,” Walsh said.
For more information on the study, contact Dr. William Cornwell: [email protected] or 303-724-2085.