by Lisa Spellman
At the American College of Cardiology meeting in March Tom Porter, M.D., presented conclusive findings that show diagnostic ultrasound-induced cavitation of microbubbles reduce the size of a heart attack significantly and restores the pumping function of the heart muscle in patients suffering from acute myocardial infarction.
The findings are the culmination of more than 10 years of research that started with a simple desire.
“We wanted to find a way to help patients that would be less costly, less invasive and be more readily available to people world-wide suffering from a heart attack,” Dr. Porter said.
Dr. Porter is the Theodore F. Hubbard Chair of Cardiology and a professor in the UNMC College of Medicine.
The solution Dr. Porter proposed was to use microbubbles that would be injected intravenously into the patient. These are routinely used during an ultrasound examination to improve the image of the heart. However, when exposed to a high intensity ultrasound, the microbubbles undergo a process called cavitation, which destroys the blood clot, Dr. Porter said.
When applied to the chest wall over the region of the heart in a patient having a heart attack, the cavitation process destroys any blood clots in both the large and very small blood vessels of the heart.
This process restores blood flow to the large blood vessel and the very tiny capillaries that supply nutrients to the heart, he said.
“The best part is this cavitation process can open up these smaller blood vessels that also might be clogged and clear those as well, preventing further damage to the heart muscle,” Dr. Porter said.
The findings came from a study of 100 patients that began in 2014 in San Paolo, Brazil in which half of the patients were treated with microbubbles and half were not.
In those who received the microbubble intervention, all of them had a smaller heart attack as measured 72 hours after the event with an MRI. This improved the pumping function of the heart at follow-up examination, so that the number of patients that needed to be treated with a defibrillator six months later was reduced from 16 percent to four percent.
“We have been waiting a long time to find a safe treatment that would reduce microvascular obstruction which can occur even with a successful stent procedure,” Dr. Porter said.
The next step of the research is deployment of the technique in an ambulance setting, which begins this month in Amsterdam. It would be done using a portable ultrasound device and commercially available microbubble infused into the patient experiencing the heart attack intravenously while the person is being transported to the hospital via ambulance.
“We chose Amsterdam because it has centralized all of the heart attack patients to go to one hospital using a network of ambulances, one or two of which we will designate to use a portable ultrasound machine,” Dr. Porter said.
“We are very hopeful that this process can be used in other areas of organ injury and help to restore blood flow quickly to reduce damage, like we know it does in acute myocarditis,” he said.
University of Nebraska Medical Center