The heart beats between 60 and 100 times per minute when at rest. That frequency can speed up during physical activity, for example, or slow down when you sleep. A beat may even be skipped sporadically. The organ has some room for maneuver, but when the rhythm of the heartbeat is frequently irregular, it may mean that the heart is not pumping blood well. In medical jargon, this dysfunction is known as arrhythmia, an alteration of the heart rhythm due to going too fast (tachycardia) or too slow (bradycardia). And in either case, there is a vital danger: the heart can fail and cause sudden death.
David Andújar, 50, spent several weeks with his heart on edge. His body warned him for days: he could barely walk, his chest hurt and at his job, in construction, “he ended up kneeling and unable to breathe,” he says. At first, they blamed it on anxiety, but after a month of these symptoms, his heart gave out: he suffered a serious heart attack that left his cardiac function at 31% of his capacity. At the Hospital Clínic in Barcelona they operated on him to normalize blood circulation, but the organ was so damaged that the high risk of him suffering sudden death forced his doctors to take more forceful measures. Andújar needed a pacemaker to regulate the rhythm of his heart and an implantable automatic defibrillator (ICD) to always accompany him to resuscitate him if his heart stopped. The cardiologists at the health center analyzed his case and favorably assessed his profile to incorporate him into an international study to validate a new generation of devices, less invasive and wireless, that reduces the risk of complications associated with these devices, such as long-term infections. that these systems can cause within the body.
Some heart diseases can cause these dangerous irregular rhythms that put you at high risk of sudden death. There is no cure or treatment beyond preventive: that is, an implantable automatic defibrillator (ICD) that works, at the same time, as a pacemaker and defibrillator, controlling the rhythm of the heart and delivering an electrical whip that resuscitates the organ in the event of a possible stop. cardiac. In Spain, around 8,000 defibrillators are implanted every year and, although they are effective, they are not free of risks, such as infections and other complications derived from the graft of an external device in the heart.
The traditional ICD is a kind of little box with a battery placed under the skin and from which a cable comes out with electrodes that reach the heart. “The transvenous ICD, the conventional one, has the function of an ICD and a pacemaker because it has a cable that goes to the heart and can stimulate if the patient has bradycardia or, if he has tachycardia, treat it in two ways: depending on the tachycardia, you can stimulate [el ritmo] and do antitachycardia therapy, which allows you to stop the tachycardia in a painless way; or if not, what it does is a defibrillation, which is more painful and creates anxiety for the patient,” explains José María Tolosana, cardiologist at Hospital Clínic and researcher in the Pathophysiology and Treatment of Cardiac Arrhythmias group at IDIBAPS. It is an effective device, but in the long term it can be accompanied by adverse effects, due to the infections that these cables generate within the body, the breakage of some part of the device or the displacement of the electrodes. Recently, to combat these complications of the transvenous ICD, a subcutaneous one has begun to be used, which does not enter the heart—the entire device is placed at chest level, under the skin—but this is also imperfect: it does not allow pacing for slow heart rates or pacing for fast heart rates, which help stop tachycardia by preventing a shock electric.
An international investigation in which researchers from IDIBAPS-Hospital Clínic have participated has now gone one step further and has validated, in a trial involving Andújar and other 160 patients from several countries, a new less invasive device for people with ventricular arrhythmias. serious illnesses that are at serious risk of sudden death. It is a pacemaker in the heart and a subcutaneous defibrillator that, in some way, talk to each other to avoid or stop those heart rhythm dysfunctions that can lead to sudden deaths. With no cables involved, the study has shown that the two devices communicate perfectly with each other through radiofrequency waves, allowing all the traditional benefits of the pacemaker and implantable defibrillator inside the heart, but without the risks and long-term complications. term associated with the more invasive versions of these devices.
“The ICD is in charge,” says Tolosana, who participated in this study, published in the prestigious medical journal The New England Journal of Medicine. The subcutaneous defibrillator commands, orders and disposes. And the pacemaker, which is a small, wire-free cylinder placed in the heart, listens, notes, and executes the ICD’s instructions when it is called to do so. “The subcutaneous ICD is totally extravascular. It goes under the skin and acts like defibrillating paddles. But with the pacemaker that talks to him, allows us to do like a transvenous, allows us to do antitachycardia therapy and complements it, closing the circle. We open the door to a new technology,” summarizes Tolosana.
Lluís Mont, head of the Atrial Fibrillation Unit and the Pathobiology and Treatment of Cardiac Arrhythmias group at IDIBAPS, gives a practical example: “If we have a patient with a heart that fires and has a tachycardia at 200 beats per minute, The ICD sends that information to the pacemaker to perform antitachycardial stimulation. If you do not stop it, the defibrillator does the shock electric”. Mont points out that the great novelty is this communication system between the ICD and the pacemaker, a dialogue that, until now, could only be done “with devices with cables inside the heart”, with the risk that they may break or infect.
Andújar, one of the first patients with this new generation of chest devices, breathes easy. He has not had any scares since the major heart attack, but he feels safer knowing that these devices, whose effectiveness and safety have just been validated in the clinical trial, ensure his survival. “At first, you feel strange because you have a machine in your body that does the function of your organ and it is an anomaly. But it has improved my life. My heart is still damaged, but it has given me a better life,” he says.
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