Coronary Artery Disease
What is coronary artery disease?
In coronary artery disease, the vessels (arteries) are affected, which supply myocardium on the surface of the heart with the required oxygen and nutrients. Old-age and many other factors cause stiffness of these vessels that are soft and flexible. They grow into the vessel over time and are called “plaque”. These plaques grown enough and eventually prevent coronary artery blood flow. Also, the plaques affect the surface of the vessel, which is smooth and not rough, and make it rough. These rough surfaces may lead to formation of clot, and these clots may completely prevent blood flow in time and result in sudden atherosclerosis.
What are the effects of coronary artery disease?
In coronary artery disease, the volume of the blood to myocardium is decreased in narrowed coronary arteries. The complaints such as tiredness, tightness of chest, feeling of heaviness, burn, pain that is usually felt in the left arm, and pain that radiates to the jaw are the symptoms of decreased blood flow. Exercises and stress that increase the heart’s need for blood can initiate such complaints which usually disappear when resting.
If coronary artery becomes blocked instantaneously, the blood flow to that area of the heart is immediately stopped. In this case, some myocardium becomes permanently damaged. This usually occurs with a chest pain that does not go of and remains for a long time, and is called myocardial infarction or heart attack. In an infarction, myocardium recovers as a tissue that is called scar tissue and incapable of contracting. If the scar tissue is small, recovery will be quick; if it is large then ability of heart to pump the blood is affected and the working capacity of the heart is decreased.
What needs to be done to remove the coronary artery stenosis?
The plaques causing coronary artery stenosis are usually located in certain part of artery. Diameter of the vessel is often normal up from the narrowed portion. If coronary artery disease involves one or two vessels, the stenosis can be enlarged without the need of a surgical procedure. This procedure can be performed by a small balloon and is called balloon angioplasty (PTCA). If coronary disease involves more than one vessel and is complicated, coronary artery by-pass surgery will be required. New vessels are attached that supply blood to narrowed vessels in this surgery.
The heart has 4 valves. Problem can occur in one or more valves depending on various causes in any time of life. The cause can be either congenital or hereditary. The most affected valves are aortic and mitral valves. Thirdly however the tricuspid valve can also become affected and cause problems. The disease of the valve is that the blood flow is decreased as result of narrowed valve, or the blood retrogrades as a result of failure. Stenosis or failure can occur individually or in combination of the two.
Since this disease of the cardiac valves will further increase the load of the heart, it may lead to irreversible disorders of cardiac structure when prolonged.
Aneurysm refers to ballooning of major vessels and is life-threatening. This ballooning can occur at very outlet of the heart (in the chest cavity), or in the abdominal cavity. If it is larger than 4 cm then it must be operated.
Carotid disease refers to stenosis of neck vessels supplying the brain and is quite common in cardiac patients. These vessels may result in numbness of hands, dizziness, stroke, or even death. Each patient who will undergo a cardiac surgery is therefore checked before the operation and will be operated if necessary.
Atherosclerosis (Blockage of saphenous veins)
Atherosclerosis, a systemic disease, may affect coronary vessels as well as saphenous veins, resulting in complaints such as pain and difficulty in walking. If the patient is unable to walk more than 50 meters, surgical intervention called peripheral by-pass must be performed.
Rhythm Disturbances (Atrial Fibrillation)
Our heart is divided into four chambers. From upper to lower division, the chambers in each half of our heart are upper (atrium – auricle) and lower chambers (ventricle) and form two adjacent pumps. The pumps operate in a two-stage cycle at one beat of the heart. Initially, smaller atria (auricles) contract and fill the relaxed ventricles with blood. In half second, strong ventricles contract and pump the blood to body circulation when atria are relax and filled. For an effective blood circulation, this contracting and pumping system needs to function in a rhythmic harmony. Additionally, for an effective blood circulation, a normal heart needs a control for proper heart rate, which varies between 60 and 100 beats per minute, when body is relaxing. Regulation of these two factors is performed by electrical system of the heart. Normally, each heart beat is caused by a group of specialized cells called sinoatrial node. Sinoatrial node in the upper atrium is the natural pacemaker of your heart. It has ability to spontaneously produce electrical stimulus initiating heart beats. Normal cardiac rhythm is called “sinus rhythm”.
Cardiac arrhythmias can occur at any stages of formation of defects in the heart’s electrical system. Arrhythmias are classified according to origin of cause (atria or ventricles), or heart rate they cause. Tachycardia – more than 100 beats per minute – refers to speed heart rate. Bradycardia – less than 60 beats per minute in resting – refers to slow heart rate. Each tachycardia or bradycardia does not necessarily indicate a disease. For example, sinus tachycardia is normal during an exercise when the heart accelerates to supply tissues with oxygen-rich blood. The resting heart rate of athletes is under 60 beats per minute since their heart function highly efficiently.
Atrial fibrillation refers to fast and disorganized beat of atrium chambers and is the most common arrhythmia. The risk of atrial fibrillation primarily occurs after 65 years old and is increased with age and depending on normal abrasion and wear that may affect functions of your heart. Electrical activities of atria become inharmonic during atrial fibrillation. Atria beat so fast (up to 300 to 400 beats per minute) that they begin to vibrate (fibrillation). Electrical waves have the same disorganized activity resembling when you throw a handful of pebbles in a calm pond. Electrical complexity of heart atria causes disorganized function of ventricles. The pulse is therefore sometimes fast and sometimes slow, and vibrant in some beats and weak in some beats.
Atrial fibrillation is the most common clinical rhythm disturbance. Structural heart diseases, e.g. rheumatic heart disease, hypertension, cardiac failure, are important risk factors for development of atrial fibrillation. In addition to symptoms reducing the quality of life, atrial fibrillation leads to complications such as systemic emboli, hemodynamic disturbance, and myopathy associated with tachycardia.
There are three ways to ensure sinus rhythm in patients with atrial fibrillation:
1. By medication; A group of drugs is successful in restoring sinus rhythm in patients who have recently experienced atrial fibrillation (AF). The success rate is decreased by duration of AF period and presence of a concomitant heart disease.
2. By angiographic methods can be attempted by inactivating specific transmission ways of the heart through a method called “catheter ablation” in angio, and if there is not any other concomitant heart diseases in AF cases that have caught early.
3. Transmission system of the heart causing arrhythmia is disabled by a surgery to constitute normal sinus rhythm.