The Impella heart pumps, produced by Abiomed (Johnson & Johnson group), were recently the subject of a safety “alert” from the Food and Drug Administration (FDA), the US regulatory body: the use of these devices is believed to be the cause of 129 cases of injury, including 49 deaths, in patients with acute cardiac symptoms. Yet over the years, Impella pumps have become widely used in clinical practice and continue to accumulate evidence of survival benefits. Interviewed by Salute, Claudio RussoDirector of the Cardiac Surgery and Heart Transplant Unit of the Niguarda Hospital in Milan (one of the hospitals of excellence for cardiology), clarifies.
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When the heart can’t pump
There are circumstances in which a heart needs help to perform its pumping function. It happens in the case of acute myocardial infarction, for example: “Ischemia sometimes involves so much heart muscle that it compromises the ability to pump oxygenated blood from the left ventricle beyond the aortic valve throughout the body – explains Russo – In the most serious, the patient can evolve towards a picture of cardiogenic shock: in this case, since not enough oxygenated blood arrives, peripheral tissues and organs (liver, kidneys, brain, muscles, intestine, and so on) can suffer: a extremely critical situation to avoid which it is necessary to support the heart until the possible recovery of cardiac function”.
In these scenarios, heart pumps such as Impella, in addition to conventional drug therapy, can play a crucial role. These are small turbine devices that, through the femoral or subclavian artery, are positioned beyond the aortic valve directly into the left ventricle. Once in place, the microturbine draws blood into the left ventricle to push it past the aortic valve into the peripheral circulation.
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The benefits of heart pumps
These cardiac micropumps are indicated in hospitalized patients in critical conditions of heart failure and are maintained for a variable period of time so that the heart can recover. “The mechanical support guarantees good peripheral perfusion on the one hand, and on the other the emptying of the left ventricle – specifies the cardiac surgeon – This is an important advantage because the ventricle, if it does not contract due to ischemia, dilates and consumes further more oxygen, further increasing the infarct damage to the heart muscle.”
“These systems work well: the data says so” – adds Russo, who recalls, as an example, a very recent publication in the New England Journal of Medicine in which the authors, analyzing the results of a multicenter randomized controlled study, conclude that the Impella pumps associated with conventional therapy significantly increase survival in the event of post-infarction cardiogenic shock compared to conventional therapy alone.
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On the market for some years now, Impella pumps are now widely used: there are currently over 66 thousand in the United States and around 26 thousand in the world. In over 10 years, Abiomed vice president Seth D. Bilazarian said in a statement, about 300,000 have been used. “More and more centers are using them. Obviously, adequate experience and expertise are needed, but they are easier to manage than other mechanical supports to the circulation – underlines the cardiac surgeon – ECMO, i.e. extracorporeal membrane oxygenation, for example, involves more complex installation and management”.
What are the risks?
As with any medical-surgical device, even with the choice to use an intraventricular heart pump (in patients who – it should be remembered – are already critical due to severe heart failure) there are associated risks. “Precisely because it must be positioned inside the left ventricle, the maneuver must be carried out with adequate technique to prevent the pump from tearing or even perforating the wall of the heart or damaging the aortic valve by crossing it. This risk was greater in patients such as the elderly or women, who have smaller hearts,” specifies Russo.
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The FDA warning (which is not the first that the agency has issued regarding Impella pumps) was necessary not only because of the reports of injuries and deaths (the statement mentions 129 cases of injuries, including 49 deaths) following the application of the devices, but also because the manufacturing company did not promptly report the adverse events to the FDA itself, limiting itself to communicating on its website an update of the risk of perforation and that of the instruction manual for the usage.
“There is no mention of the structural danger of the system, so much so that a withdrawal from the market of these devices is not foreseen – concludes Russo – As the FDA underlines in its communication, however, it is necessary to pay particular attention during the positioning maneuvers of the intraventricular pump, making use of adequate instrumental monitoring, especially in subjects most at risk or during resuscitation maneuvers”.