Understand Cardiology procedures

Author : Bhadresh Bundela

Cardiology procedures

What is Coronary Angiography?
Coronary Angiography is a diagnostic procedure to detect abnormalities of coronary arteries. During this procedure, the cardiologist inserts a thin tube called catheter into an artery in the arm or the groin. From here this catheter is guided towards the heart. The coronary arteries arise from the root of a great vessel called aorta. The catheter is placed at the mouth of the coronary arteries & a radio-opaque dye is injected into it. X-rays taken during the passage of the dye through the coronary arteries reveal any abnormality including blocks or narrowings in the arteries.

What Is Coronary Angioplasty?
Localized narrowings (“lesions”) in the coronary artery can be treated without resorting to surgery. This procedure known as coronary angioplasty entails placing a balloon at the site of the lesion & inflating it thus widening the passage. This procedure improves blood flow to the heart.
Coronary Angioplasty is a commonly performed procedure. It is usually done in the following situations:
• To improve symptoms of coronary artery disease, namely angina and shortness of breath caused by coronary blocks.
• During a heart attack to reduce damage to the heart muscle. In a heart attack blood flow through a coronary artery is completely blocked. Angioplasty is performed to clear the blocked vessel & restore blood flow to the affected heart muscle. This prevents or minimizes permanent damage to the heart muscle
What is coronary stenting?
A stent is a mesh-like metallic tube somewhat like a spring in a ball-point pen. It is used to hold an artery open after balloon angioplasty. In its collapsed form, a stent is usually less than a millimeter in diameter & is mounted over a balloon catheter. Just like an angioplasty balloon, the stent is passed into the coronary artery via the forearm or leg artery. It is then placed at the site of coronary block & expanded using high inflation pressure of the balloon. The stent remains permanently at the lesion site & acts as a scaffold to keep the artery from collapsing back to narrow size. In addition, stent placement helps to reduce the chance of recurrence of coronary blocks at the site of implantation
What are medicated stents?
When a coronary block is cleared using plain balloon angioplasty, there is a 30-40% chance that the block will recur. This process is called as restenosis. Stent placement at the lesion site reduces the chances of restenosis to about 15-20%. Medicated stents or drug-eluting stents are latest form of technology to combat this problem of recurrence. In a DES, an ordinary stent is coated with a special medication. After stent placement, the medication is leached slowly into the surrounding blood vessel & this prevents restenosis. With DES, restenosis rates are generally about 5-6% in most cases.

Peripheral Artery Disease
Similar to the blocks that develop in the coronary arteries, the lipid deposition in other arteries of the body can cause blocks. Commonly, such blocks are noted in the arteries of the thigh & legs, the aorta, the arteries of the kidneys & the arteries of the brain.
The symptoms for blocks at non-cardiac arteries can be varied. Blocks in the leg arteries lead to calf or leg pain on walking, Blocks in the kidney arteries cause high blood pressure & poor functioning of kidneys, blocks in the brain arteries cause minor or major strokes.

Detection of Peripheral Vascular Disease:
Based on the symptoms, appropriate noninvasive tests are performed to detect peripheral vascular diseases. Commonly, Doppler ultrasound is the first test to be ordered by the doctors. Subsequently a CT angiography or an MR angiography can confirm the existence & the severity of the blocks. The latter two tests also enable the doctors to plan appropriate treatment for the blocks. Treatment may be in the form of medication alone, angioplasty or surgery, either alone or in combination.

Peripheral Angiography & Angioplasty:
Sometimes if the non-invasive tests are inadequate doctors may advise peripheral angiography to be performed. The principles of the test are similar to that of coronary angiography. The main difference is that, since unlike the heart, the legs, brain etc are not constantly mobile, a special technique of angiography termed as Digital Subtraction Angiography can be employed which enables better visualization of the blocks with lesser quantities of dye injected.
If the blocks are amenable to treatment by angioplasty, the procedure is similar to the coronary angioplasty. Peripheral angioplasty is performed using a catheter to access the concerned artery. A guidewire is passed across the narrowed segment and a balloon is threaded over this wire to the site of narrowing. Then the balloon is expanded to widen the passage for blood. Stents are sometimes used to keep the artery open. The procedure is performed under local anesthesia.

What is Arrhythmia?
Human heart beats rhythmically all the time to maintain life. While the rate at which the heart beats may vary from sleep to activity, the rhythm is nearly constant. Any variation from this regularity in rhythm is termed as an arrhythmia. Many rhythm abnormalities are associated with variation in heart rates also. Heart arrhythmias with faster heart rates are known as tachyarrhythmias
Some tachyarrhythmias such as ventricular tachycardia or ventricular fibrillation are life immediately threatening. Other arrhythmias like supraventricular tachycardia or atrial fibrillation may not be immediately life threatening but may affect the quality of life of the patient & may cause shortening of overall life-span due to complications

Diagnosis of arrhythmias
An electrocardiogram (ECG) taken during an episode of arrhythmia usually gives the doctor as to the nature of the arrhythmia. In addition, the doctor can also know the region from where the arrhythmia has originated in the heart & plan appropriate treatment.
Sometimes because the arrhythmia is a short episode, the patient may not be able to reach the hospital in time for an ECG record. In such cases Holter monitoring is advised. In this test electrodes attached to the patients body under his or her clothes monitor the heart rhythm and every beat of the heart is recorded in a pocket recorder through these electrodes for a 24 or 48 hour period. The recorded data is analyzed later & if an arrhythmia has occurred during this recording period, the diagnosis can be confirmed.

Further testing: electrophysiology study
Sometimes the symptoms of an arrhythmia are very typical but due to the unpredictability of the timing of the arrhythmia, neither an ECG nor a Holter record is able to capture the episode. In such a case, an electrophysiology (EP) study is advised. In this procedure, the doctors stimulate the heart to produce the arrhythmia in the Electrophysiology Lab so that the nature & origin of the arrhythmia can be identified. The specialist cardiologist who performs this procedure is known as an Electrophysiologist.
Once the test is completed and a diagnosis is obtained, the electrophysiologist can advise an appropriate treatment for the arrhythmia, which may be: medications, radiofrequency ablation for the arrhythmia, pacemaker or an implantable cardioverter defibrillator (ICD).

Radiofrequency ablation
In many cases of arrhythmia, radiofrequency ablation maybe advised as a continuation of EP study. Here, high-frequency sound waves are applied at localized regions in the heart to destroy abnormal tissue that causes the arrhythmia. The application of these waves will be through catheters inserted into the heart via a vein in the groin & so this form of treatment is called ‘Catheter ablation’ & is performed in the cardiac catheterization lab.
During heart surgery, the abnormal tissues which cause arrhythmias can be eliminated either by catheters applied directly over the heart or by cutting them up using a surgical knife. This type of ‘surgical ablation’ is usually performed in patients who undergo concomitant heart surgery (e.g. coronary bypass grafting or heart valve surgeries) & is performed in the it cardiac operation theatre.

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