Diagnostic Cardiac Procedures

Cardiac Angiogram:

Angiograms are performed under local anaesthetic.

You may be given a light sedative before the procedure to help you relax. This procedure is performed in a Cath Lab which is a specialised Hospital theatre.

The procedure involves inserting a fine plastic tube called a catheter into an accessible artery, usually in your wrist but sometimes the groin is used if we cannot use your radial artery. Your cardiologist will decide when examining you, which is the best approach for you.

The procedure is performed under x-ray control; the catheter is threaded up to the heart where a special dye (contrast Media) is injected and a series of x-ray pictures are taken from different angles. At the end of the procedure a small tube (sheath) is left in the artery in your wrist/groin. This is usually removed a few minutes later, depending on the amount of medication given during the procedure.

The outcome of this test will determine your treatment.

You may require Coronary Angioplasty, which involves insertion of a stent into an artery, you may require cardiac surgery, or you may need medication to assist with your symptoms.

To determine the need for a stent (angioplasty) often a pressure wire or FFR (fractional Flow Reserve) measure will be done see FFR

Atherosclerosis

Pressure wire study or FFR (Fractional Flow Reserve) measure.

A pressure wire study is a tool to assess the flow pressure (fractional Flow Reserve) through a coronary artery. It is used to determine whether the narrowing observed on a coronary angiogram limits flow and therefore is producing ischaemia (lack of blood flow to muscle). The operator can then decide whether to proceed to angioplasty of that narrowing, if the patient requires surgery, or if actually the lesion does not need treatment, or can be medically managed. It can therefore reduce the risk of further treatment, or assess the need for surgery.

The pressure wire is a specialised wire with a tiny microchip that measures pressure flows in a coronary artery. A drug called adenosine is given intravenously while doing the study.

‘Full’ Heart Study

This is a procedure done using a specialised catheter and is done to determine the pressures in the right and left heart chambers of the heart and pulmonary artery bed.

It is a diagnostic tool for evaluating the effects of valve disease on the heart. It can also give a measurement of cardiac output – how much blood your heart is able to pump out at each heart beat.
A full heart study can also help diagnose atrial septal defects’s and patent foramen ovale’s by taking multiple blood gas samples in the heart chambers, large veins and arteries to determine oxygenated and deoxygenated blood flow/mix in the heart.

The ‘right’ heart study is done first and access is through the femoral vein. A coronary angiogram follows and access is through the femoral artery.

A left ventriculogram may be done . This involves injecting dye or contrast into the left ventricle of the heart. It can assess the pumping action of the heart and how well the Aortic and Mitral valves are working.

Transthoracic Echocardiogram -TTE

This the most common type of echocardiogram, which is a still or moving image of the internal parts of the heart using ultrasound. In this case, the probe (or ultrasonic transducer) is placed on the chest or abdomen of the subject to get various views of the heart. It is used for a non-invasive assessment of the overall health of the heart, including a patient’s heart valves and degree of heart muscle contraction (an indicator of the ejection fraction). The images are displayed on a monitor for real-time viewing and are also recorded.

An echocardiogram can be used to evaluate all four chambers of the heart. It can determine strength of the heart, the condition of the heart valves, the lining of the heart (the endocardium), and the aorta. It can be used to detect any weaknesses or abnormalities of structure or function of your heart.

“Bubble contrast TTE” involves the injection of agitated saline into a vein, followed by an echocardiographic study. The bubbles are initially detected in the right atrium and right ventricle. If bubbles appear in the left heart, this may indicate a shunt – a movement of blood from the right side of the heart straight through to the left side , such as a patent foramen ovale, atrial septal defect, ventricular septal defect or arteriovenous malformations in the lungs.

Trans Oesophageal Echo – T.O.E

T.O.E is an alternative way to perform an echocardiogram. A specialized ultrasound probe containing an ultrasound transducer at its tip is passed into the oesphagus. This allows the echo to image and Doppler evaluation the heart as close as possible. This gives a very clear picture of structures within the heart and also enables accurate recording of flow in the heart and through the heart valves.

It is performed to diagnose valve disease, patent foramen ovale, atrial and ventricular septal defects, tumors and presence or absence of clot in the Atrial appendage.

To be able to tolerate the procedure you will be given sedation and your throat will be sprayed with local anaesthetic and you will usually be asked to gargle it.

It is important to note that you cannot drive for 24 hours following the sedation given and that you should have someone stay with you overnight.

Your ability to swallow afterwards will be tested and you should not have very hot food or beverages to swallow in case of burning.

Interventional Cardiac Procedures

Angioplasty

Coronary angioplasty is a non-surgical means for opening blocked coronary arteries using fine tubes called catheters introduced usually from the wrist or sometimes the groin is used. Most narrowings are best treated with balloons and stents (fine mesh tubes). Stents reduce the chance of renarrowing.

Angioplasty is carried out in an angiography suite (theatre) called a “cath lab”.

Under local anaesthesia, a specialised tube (sheath) will be placed in your wrist or groin through which a guiding catheter is passed up to the coronary arteries.

Your interventional cardiologist uses the X-ray screen to track the path of the catheter.

Through the guiding catheter, a wire about the thickness of a hair is passed across the narrowing.

A stent (a fine mesh tube, which comes squashed down on a balloon) is directed across the narrowing over a wire. The balloon is inflated to expand the stent and artery. The stent is pushed into the artery wall holding the artery open.

The balloon is deflated and removed leaving the expanded stent in place. Once expanded the stent cannot move. For some patients the artery is widened by a balloon alone.

Following coronary angioplasty you will need to take an antiplatelet drug for usually up to a year.

Clopidogrel (Plavix) https://www.healthnavigator.org.nz/medicines/c/clopidogrel/
https://www.heartfoundation.org.nz/your-heart/heart-treatments/medications/antiplatelet-agents/

Restenosis (renarrowing)

Although stents reduce the chance of renarrowing of the angioplasty site, it can still occur. It is due to the healing of cells growing through the mesh of the stent. It is most common between 6 weeks and 6 months after stenting . It is more likely to occur in small diameter arteries, long narrowings and in diabetic patients. If it does occur, it is usually possible to treat the artery again.

Types of Stents:

Bare metal stents – these are a fine mash tube with no drug coating. They may be used in patients that require surgery or cannot take anticoagulants.

Drug Eluting Stents (DES) – These are bare metal stents covered with a drug with is then ‘eluted’ or released over a period of time. The drug reduces the inflammetry responce from the endothelial cells in the artery. It reduces the possible production of clot or thrombus which may block off the stent and also reduces the possible extra production of cells which may migrate into the stent and artery lumen, narrowing and blocking the artery.

Scaffolds:
These are resorbable stents (scaffolds) that will hold the artery open but will reabsorb into the body within a given amount of time. This is new technology and the implanting is limited to specific criteria such as where the narrowing is in the coronary artery system, how large the vessel is and how long the narrowing is.
See video

Structural Heart

BAV – Balloon Aortic Valvuloplasty- a procedure to treat Aortic Stenosis(AS)

AS can be due to degenerative/calcified, bicuspid valves or rheumatic disease.

Aortic stenosis, also called aortic valve stenosis is a condition where the aortic valve has become narrowed or constricted (stenotic) and doesn’t open or close properly.

When the aortic valve become stenotic the ability of the left ventricle to pump blood out of the heart into the aorta and other arteries is impaired, and the organs receive an insufficient supply of oxygen rich blood. This impairment results in blood “back flowing” into the lungs and causing shortness of breath.

Valvuloplasty is done to relieve the stenoses and improve the symptoms of AS.

BMV – Balloon Mitral Valvuloplasty

TAVI – Trans Aortic Valve Implantation or TAVR -Trans Aortic Valve Replacement

Trans Aortic Valve Implantation or TAVR -Trans Aortic Valve Replacement

TAVI or TAVR, is the replacement of the aortic valve of the heart through the blood vessels (as opposed to valve replacement by open heart surgery).

The use of a multidisciplinary team of cardiologists, cardiovascular surgeon, and supporting group (for example, imaging specialists, geriatrician, cardiac anaesthesiologist) , benefits patients and has enabled TAVI to become the standard of care for inoperable, high risk and intermediate risk patients with severe aortic stenosis.

The catheter procedure was developed in France, initially performed in 2002 on April 16 by Prof Alain Cribier in Hospital Charles Nicolle, at the University of Rouen. It is now approved in more than 50 countries.

TAVI offers:

  • A minimally invasive procedure.
  • No heart lung machine.
  • A decrease in patient morbidity.
  • Early ambulation and patient comfort and improved quality of life .
  • It saves lives for high and intermediate risk patients.

Mitral Clip – Clipping of the Mitral Valve

The Mitra Clip (trademark Abbott) procedure is a percutaneous repair of the Mitral Valve. It involves passing a specialised sheath and delivery catheter system through the femoral vein, into the right atrium and accessing the left atrium of the heart by crossing the atrial septum. The ‘clip’ is then manoeuvred into place using guidance from 3D T.O.E and fluoroscopy. The Clip is released from the delivery system when it has ‘captured’ the cusps of the valve and it can be seen on Echo that it is placed central to the regurgitant jet. The procedure may require two clips to adequately clip the valve.

The procedure has a positive safety profile. It causes a reduction in mitral regurgitation. It has favourable left ventricular remodelling and improvement in patient symptoms, therefore producing a reduction in hospitalizations for heart failure.

https://www.vascular.abbott/us/products/structural-heart/mitraclip-mitral-valve-repair.html

ASD / VSD/ PFO closure – Atrial septal defect / Ventricular Septal defect / Patent Foramen Ovale

LAA closure – Left Atrial Appendage Closure

Other diagnostic procedures not done at MCVS. These are done at other facilities.

  • CT angiogram- computed tomography angiography
  • Perfusion scan
  • ETT (excercise tolerance test)
  • Neuclear Med scan
  • Holter monitor
  • MRI
  • Plain film Xray