OUR TREATMENTS

Cardiology

PTCA and stents

PTCA stands for Percutaneous Transluminal Coronary Angioplasty. PTCA is carried out to reopen a blocked artery in the heart. A special tube called a catheter is placed in an artery, commonly the femoral artery. This catheter has a deflated balloon at the tip. Under X-ray guidance, the cardiologist advances this catheter into the blocked artery of the heart. When it is in position, the cardiologist inflates the balloon, thereby opening up the blocked artery and blood can then flow through the artery again. At this time, a small reinforced tube called a stent may be inserted to the blocked area via the catheter. This works by helping to stop the artery from becoming blocked again. The balloon is then deflated, leaving the stent in place. Occasionally the artery can block again over time to cause a condition called restenosis. If this happens, the cardiologist may have to repeat the procedure. Stents used to be made from bare metal. Unfortunately, these had a high probability of restenosis. Recent advances in stent technology are having an impact on restenosis. These new stents are called drug eluting stents. As the name suggests, they have a drug impregnated into them that helps stop the restenosing process.

Patients come in for the procedure and go home the next day. For any coronary invasive intervention, there are associated risks. During the procedure, the artery can completely block. Depending on the importance of this artery, it may be necessary to undergo an immediate bypass graft operation. This is a rare event, with approximately one out of every two hundred people undergoing PTCA converting to coronary artery bypass graft surgery (CABG). A detailed discussion of the risks versus benefits with the cardiologist will provide an individual guide prior to the procedure.

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Radiofrequency ablation

The heart beats as a result of coordinated message activity between its electrical generator, the sinoatrial and atrioventricular node, and its pump, the left ventricle. This is known as cardiac conduction. Some people experience extra beats or palpitations due to abnormal conduction messages reaching the ventricles. There are different types of abnormal conductions, and depending on the type, the cardiologist may choose to treat this condition with radio frequency ablation (RFA). This can be carried out at the same time as an electrophysiology study.

RFA involves a procedure similar to that of a cardiac angiogram. A tube is inserted into a vein or artery and an electrode is passed through this tube, up the body and into the area of the heart that is responsible for the extra beats. A small amount of energy is then delivered from the electrode tip to the precise point in the heart. This energy kills the cells responsible for the aberrant conduction rhythm. This is an extremely effective form of treatment for SVT, with long term studies showing successful RFA treatment is persistent over time, and that late recurrence of aberrant conduction is a rare event.

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Pacemaker

Despite the different types of pacemaker, essentially they all have the same function – to detect and act as the hearts pacemaker if an abnormality in rhythm is detected. There are specific abnormal heart rhythms that will require a pacemaker to be inserted - if the heart beat is too slow (bradycardia) or too fast (tachycardia), if there is a irregular heart rate, heart failure, or when the heart does not receive the normal signals sent out by the sinoatrial node. This is termed heart block. Sometimes electrical impulses generated by the heart’s normal pacemaker are not transmitted to the ventricles quickly enough. This is often referred to as a conduction abnormality. Heart failure can cause this, as well as some drugs and cardiac surgery. Heart block has various well defined stages with the last stage resulting in complete heart block. In this stage, no information from the heart’s normal pacemaker reaches the ventricles. Luckily, the ventricles have their own built in pacemaker, though this is insufficient in providing the amount of blood the body needs to function adequately. As a result, fainting is a common problem with this form of heart disease. Pacemakers therefore provide an adequate pulse rate when the heart’s rate is abnormal.

There are 3 different types of pacemaker – single chamber, dual chamber and biventricular chamber. For the single chamber pacemaker, a very small electrode wire is inserted into a large vein, normally a vein near the shoulder. This wire is the guided under X-ray by a cardiologist into the right atria or ventricle of the heart. The wire at the skin is then “tunnelled” away from the insertion point, and a small pocket is made under the skin where it is attached to the actual pacemaker box. For a dual chamber pacemaker, the same technique is used but there are 2 leads. One lead is guided to the right atria and the other to the right ventricle. A biventricular pacemaker has 3 leads or electrodes that are guided into the right atria and right and left ventricle. Depending on the type of rhythm or severity of heart disease, the cardiologist will choose the most appropriate one.

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Percutaneous atrial septal defect closure (ASD)

An ASD is a hole in the atrial septum that allows a portion of blood returning to the left atrium to flow back to the right atrium, right ventricle and pulmonary arteries, thereby placing additional work on these heart structures as well as the lungs. Depending on the size of the hole and the amount of blood that passes between the two atria via the defect, a heart murmur is produced that is usually identified as an abnormal finding when the person is still a child. Occasionally people reach adulthood without knowing that they have an atrial septal defect. Left untreated, atrial septal defects may lead to right heart failure, atrial arrhythmias, ventricular dysfunction, and pulmonary hypertension. Although an ASD may produce no symptoms for many years, eventually the excess flow of blood through the defect in the atrial wall, produces an extra burden on the heart and pulmonary arteries. Patients usually develop symptoms of fatigue or shortness of breath in their 20's or 30's. Occasionally patients only present years later with their first symptoms. The symptoms are due to stretching of the heart chambers, increased pressures within the heart, and eventual weakening of the heart muscle on the right side of the heart. When this occurs, the patient may also develop abnormal heart rhythms such as atrial fibrillation or atrial flutter with rapid heart beats which exacerbate the feelings of weakness and shortness of breath.

The standard recommendation for patients who are found to have an atrial septal defect is to have the ASD closed. In the past the only option for the patient was to have an open heart surgical operation. Over the past 15 years, new techniques have been developed to close these ASD’s using a catheter guided system.

The most common treatment for ASD is to have Percutaneous ASD closure. This involves a small tube placed into the femoral vein. A catheter is then passed into the vein and advanced up to the heart under X-ray guidance. An ultrasound may be used to measure the defect size and to visualize the heart and blood flow. Once the defect has been identified and measured, a small closure device is placed via the catheter into the heart to close the hole between the two chambers, thereby restoring adequate blood flow.

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Implantable cardioverter defibrillators

The heart is a complex pump which relies on a specific rhythm with which it can work normally. There are many types of heart rhythm; some can be tolerated by the body reasonably and others cannot. 2 types of rhythm which are not well tolerated are Ventricular tachycardia (VT) and Ventricular fibrillation (VF).

VT is a rhythm whose origin is initiated somewhere in the ventricles, instead of the atria. This causes the heart to beat very rapidly. The heart cannot fill adequately in this rhythm, making the patient feel light headed and weak. This can lead to fainting if not corrected promptly. It can also lead to death if not treated at all.

VF is more serious than VT. In VF, the heart has no coordinated activity. There are a multitude of signals sent out in all directions across the heart. Due to the chaotic activity, the pumping mechanism is totally ineffective. This is a medical emergency, and if not treated promptly, results in death.

ICD’s are extremely effective at treating these 2 potentially lethal rhythm abnormalities (Arrhythmias). A wire electrode is inserted in a vein near the shoulder, in a similar way to a pacemaker wire. This is introduced into the correct position in the heart by a cardiologist. A small pocket is then made underneath the muscle high up on the chest, commonly the pectoris muscle. The ICD is placed here and the electrode tunnelled from its insertion point and attached.

When fully operational, ICD’s monitor the heart rate and rhythm. When it detects an abnormality, it will initiate pacing if the rhythm is VT, or it will deliver a small electric shock if the rhythm is VF. This is because in VF, the heart is completely chaotic. The shock delivered will temporarily stop the chaotic activity and allow the hearts normal pacing system to assume control.

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ECP

ECP stands for External Counter Pulsation. It is an effective treatment for a form of angina called Chronic Refractory angina. This means that despite optimum medication and surgical intervention, a patient may still suffer from angina pain.

ECP works in a number of different ways. It reduces the resistance that the heart has to overcome before being able to pump blood to the body. This is known as afterload. It increases the amount of blood flowing through the coronary arteries during its resting phase (diastole), and increases the amount of blood returning to the right side of the heart. ECP appears to exert its coronary artery effects by increasing the amount of pressure in a narrowed artery, thereby opening up collateral channels around a blockage such as atheroma in heart disease. It also has a mild exercise effect on the heart. Athletes have well established collaterals, due to the amount of exercise that they have to undertake and their general level of fitness.

Inflatable cuffs are placed around the calfs, thighs and buttocks. A continuous ECG is taken of the heart and analysed. Inflation and deflation of the cuffs is rapid and timed precisely to the ECG or heart rhythm. Treatment consists of 35 one hour sessions. Research conducted at a leading American university hospital has established that 35 hours is the optimum treatment time for this therapy. During its inception at the Wellington hospital, a research study was undertaken which also corroborated the previous findings. Most patients find that following completion of ECP, the amount of medication they need to take to control the angina pain is reduced significantly, with some able to cease nitrate spray completely. Exercise tolerance is also increased, with many patients reporting being able to resume activities that they previously had been unable to participate in.

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