Device Therapy for Cardiovascular Disease

Device Therapy for Cardiovascular Disease How to evaluate a device therapy: • Clinical need – (Mortality and Morbidity) • Device concepts • Device clinical trials (Efficacy, Safety, Placebo-controlled or comparative) – First in man, registries, case-control studies, randomised controlled trials TandemHeart device implantation • Clinical need: Short-term cardiac assistance, to lower the risk of death and improve hemodynamic performance and end-organ perfusion before implanting long-term assist devices in selected patients with signs of profound cardiogenic shock (which is a state of inadequate tissue perfusion due to cardiac dysfunction). • Device concept: The TandemHeart is a left atrial-to-femoral artery bypass system comprising a transeptal cannula, arterial cannulae, and a centrifugal blood pump. It is a type of Implantable mechanical circulatory support (MCS) systems that can be used to support patients in cardiogenic shock (until cardiac recovery occurs or as a bridge to definitive therapy) or as a temporary application. The Tandem Heart device comprises an extracorporeal circuit that directs blood from the left atrium to the femoral artery. A large catheter is placed across the interatrial septum, via the femoral vein, into the left atrium. Oxygenated blood from the left atrium is then continuously withdrawn into the catheter by the means of an external continuous flow centrifugal pump. • Clinical trials o Efficacy: no mortality difference o Safety: increased bleeding, limb ischaemia, disseminated intravascular coagulation (which produced thrombosis and haemorrhage) Ablation • Clinical need: used to treat some heart rhythm problem (e.g. tachyarrhythmia) and these problems may be dangerous if not treated • Device concept: procedure used to destroy small areas ion heart that may be causing heart rhythm problems o Catheter is inserted through a cut in one of the blood vessels in the area → small electrodes are placed in different areas of the heart and connected to monitors to display heart rhythm problems o Once the source of the problem has been found, one of the catheter lines is used to send electrical energy to problem area → destroys problem area, creating a small scar • Device clinical trials: o Efficacy: effectiveness (success rate) varies depending on area causing arrhythmia o Safety: Cardiac ablation is a relatively low-risk procedure (complication rate for ablation is ~1.6%). However, as with any procedure, there are risks that potentially include bleeding or bruising, swelling, blood clots, a slow heart rhythm, or perforation of the heart muscle, blood vessel, or lung. Complications from medicines used to manage arrhythmias can include fatigue, shortness of breath, dizziness, and drug toxicity. Balloon Angioplasty vs. Directional Atherectomy Clinical need • The blood flow in the carotid artery (to brain and face) can become partly or totally blocked by a fatty plaque. Partial blockage = carotid artery stenosis (narrowing). Blockage in the carotid artery can reduce blood supply to the brain and hence a stroke can occur. Device concept • Balloon angioplasty: an empty and collapsed balloon on a guide wire, known as balloon catheter, is passed into the narrowed locations and then inflated to fixed size using water pressures. Balloon crushes the fatty deposits, opening up the blood vessel for improved flow, and the balloon is then deflated and withdrawn. • Atherectomy: A procedure utilises catheter with sharp blade on the end to remove plaque from blood vessel. The catheter is inserted into the artery through a small puncture in the artery, and it is performed under local anaesthesia. The catheter is designed to collect removed plaque in a chamber in the tip, which allows removal of the plaque as the device is removed from the artery. Device clinical trials: • Atherectomy was associated with a higher incidence of death and myocardial infarction than balloon angioplasty. Furthermore, the rates of restenosis were high in both treatment groups. In a trial limited to patients with left anterior descending disease, it is demonstrated that a better initial angiographic outcome in the atherectomy group than in the angioplasty group but no difference in clinical outcome at 6 months of follow-up. Bare metal stents vs. Drug-Eluting stents Clinical need: • Usually surgery to widen or unblock a blood vessel is clinically long-lasting. However in some cases the procedure can cause a narrowing of the vessel (restenosis) → reoccurrence of stenosis restricts blood flow Device concept • Bare-metal stent is a vascular stent without a coating (as used in drug-eluting stents) → provide structural support to help keep the cleared artery open after angioplasty. Helps to prevent the artery from re-narrowing • Drug-eluting stent (DES) is a stent placed into a narrowed, peripheral or coronary artery that slowly released a drug to block cell proliferation. The stent itself is expandable. A coating, typically a polymer holds the elutes (releases) the drug into the arterial wall by contact transfer. The drug inhibits neointimal growth which causes restenosis. Device clinical trials • Drug-eluting stents were associated with an increased rate of death, as compared with bare-metal stents. This trend mainkly appeared after 6 months. Device clinical trials: • Drug-eluting stents were associated with an increased rate of death, as compared with bare-metal stents. This trend mainly appeared after 6 months.