Eastern New Mexico Medical Center serves as the receiving facility for patients having acute myocardial infarctions (MI) or “heart attacks,” both for patients in Roswell itself and for a large surrounding community. The normal standard of care is to take such patients immediately into the cardiac catheterization laboratory. In the cath lab they undergo an emergency diagnostic coronary angiogram which typically leads to opening the closed coronary artery which is causing the heart attack to occur. All this is accomplished using balloon angioplasty which initially opens the arterial blockage and sets the stage for inserting a coronary stent which generally provides the best long-term result.
Unfortunately, if the amount of heart muscle affected is large enough the patient may arrive in a state of shock, where the heart is so badly damaged that it cannot pump enough blood through the circulation.
Since approximately 1984, patients arriving in cardiogenic shock have been typically treated with insertion of a cardiac assist device called an Intra-Aortic Balloon Pump. A balloon pump catheter has a balloon at its tip which kind of resembles a hot dog casing. The catheter is connected up to a portable machine which pushes helium gas into the balloon when the heart is relaxing and the main aortic valve is closed. The expanding balloon pushes on the surrounding blood and raises the blood pressure and increases the amount of blood pushed down the coronary arteries. As the heart starts to pump blood out of the pumping chamber the machine literally sucks the gas out of the balloon making it easier for the heart to eject the blood into the circulation.
To put it more simply, the balloon pump acts as a device to take the energy from the wall current to help pump the blood around. Inserting a balloon pump often stabilizes a patient in cardiogenic shock and bridges them over the acute injury.
I first inserted an balloon pump in 1984, in the hospital where I trained, when it initially came on the market. Since then I have inserted thousands.
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Over the past 10 years a new, more advanced cardiac assist device has appeared. Called an “Impella,” this is literally a pump. The Impella sits across the aortic valve which separates the main pumping chamber, the ventricle, from the aorta, which is the giant central artery of the body. The Impella has intake openings inside the ventricle. When active the Impella literally sucks the blood out of the ventricle and ejects the blood above the valve into the aorta.
While running, the standard Impella catheter will pump 3.5 liters of blood, each minute, out of the heart and into the aorta. Normal flow at rest is about 5 liters per minute. The Impella pump can keep someone alive even when the left side of the heart is motionless due to a massive MI. Clinical studies have shown that using an Impella pump to help someone survive cardiogenic shock provides significantly better outcomes than using a intra-aortic balloon pump.
During the past year the cath lab team at ENMMC has undergone an extensive training program to be certified as competent in using the Impella device. We have been able to employ the device now in a number of patients with excellent clinical results. We have had several patients that we did not think were going to survive who we were able to successfully support with the Impella and transfer them to an outside hospital for emergency cardiac surgery. At this time we are the only Eastern New Mexico hospital facility routinely using the Impella and considered “Impella Ready.”
In addition to treating patient in cardiogenic shock, the Impella device also has a major role in supporting patients who are undergoing high-risk coronary stent procedures. It is not rare to have a patient who has been turned down for further bypass surgery but now has critical obstructions affecting a large part of the heart muscle. We now are able to routinely safely treat these patients with coronary intervention/stenting in the cardiac catheterization lab at ENMMC while supported by the Impella device, providing a much greater degree of procedural safety than using an intra-aortic balloon pump.
Ashley Rivers is a medical doctor for Heart, Vascular and Vein Specialists at Eastern New Mexico Medical Group. The advice offered in this column is that of the author.