Interventional Cardiology

  • Interventional Cardiology

    The subspecialty of interventional cardiology began with the invention of coronary angioplasty by Andreas Gruentzig, a Swiss cardiologist, in 1977. Prior to this, cardiologists were able to take pictures of the coronary arteries only. The only treatment cardiologists had to offer was medication. The only alternative treatment was coronary artery bypass surgery which is performed by surgeons who have specialised in cardiac surgery.

    Angioplasty had a significant late failure rate due to recurrent narrowings (restenosis) which formed when the lining layer of the artery overgrew in response to the procedure. Coronary stents were developed to manage this problem. The technical demands of angioplasty and stenting required additional training and experience, so the subspecialty of interventional cardiology developed. 

  • Coronary Angiography, Angioplasty and Stenting

    A coronary angiogram is a special x-ray procedure where moving images of the heart’s arteries (coronary arteries) are taken to see if they are narrowed or blocked. The coronary arteries are accessed via the femoral artery in the groin or the radial artery in the wrist, and following access, a fine plastic tube (or catheter) is inserted via X-Ray guidance into the opening of the coronary arteries and an X-Ray dye is injected into the artery. 

    In some circumstances, the narrowed or blocked artery may be treated at the time of angiography by a procedure called angioplasty. This involves guiding a tiny balloon through the coronary artery to the blockage, which is then inflated to widen the opening and increase blood flow to the heart. A stent (small steel mesh tube) is then placed during the procedure to keep the artery open after the balloon is deflated and removed.

    This is an angiogram of the right coronary artery during a heart attack. The X-Ray dye shows blood flow in the artery is stopped by a blood clot.

    A soft flexible guide wire has been passed through the catheter, down the artery and an angioplasty balloon inserted and inflated. A stent is deployed immediately after to keep the artery open.  


     

    After removing the guide wire and balloon and leaving the stent in the artery, the X-Ray dye shows the blood now fills the entire artery:

    The inner lining of the artery is disrupted which means it is very sticky or ‘thrombogenic’. Clotting at the site of angioplasty and stenting is prevented by the use of aspirin and other anti-platelet drugs such as clopidogrel (Iscover, Plavix). As the artery heals, overgrowth of the inner lining layer (endothelium) can be excessive, causing re-narrowing of the artery with tissue – ‘restenosis’. This is reduced by using stents coated with drugs which slow regrowth of endothelial tissue. Biodegradable stents which disappear when no longer needed are being studied in clinical trials but as yet unavailable.

    Download Patient Information Sheet for Coronary Angiogram, Angioplasty and Stenting here.

  • Emerging Technologies – Renal Artery Denervation

    Despite lifestyle measures and modern blood pressure lowering drugs, a proportion of patients with high blood pressure (hypertension) have persistently high BP despite multiple medications. Alternative approaches to treatment of high BP have been developed based on our understanding of the role that the nerves to the kidneys play in regulating blood pressure. 

    The nerves travel from and to the brain alongside the aorta and then pass alongside the kidney or renal artery. 

    Renal Nerves

    A new treatment has been developed which allows us to obliterate the kidney’s nerve supply using high frequency electrical energy without affecting kidney function.

     

    Renal Denervation Procedure

    The procedure involves passing a catheter into the femoral artery in the groin, in the same way we do when doing a coronary angiogram, under X-ray guidance, threading the specially designed catheter into the kidney arteries. An electrical current is then administered at several points along the artery which destroys the renal nerves.

    In recent published studies a significant reduction in BP was seen within a few weeks of the treatment. This allows patients to achieve better BP control although they continue to need treatment – just less of it for more benefit.