Angina or chest pain is a typical symptom associated with coronary artery disease. Angina is a sign that the heart is not getting sufficient blood flow. This is usually due to narrowing of the arteries (atherosclerosis. It can also be the result of extreme hypertension, hypertrophic Cardiomyopathy or valvular heart disease. Stable angina is a pain that occurs when there is extra load on the heart and occurs in a regular pattern. This type of angina pain can be tackled with medication and rest. On the other hand, unstable angina can be dangerous as it may the precursor to a heart attack. The pain in such a case is more prolonged and severe. Prinzmetal's angina or variant angina pectoris occurs due to transient spasm of the coronary artery. This does not get triggered due to physical exertion.
The pain associated with angina is uncomfortable pressure and squeezing on the chest. There is pain or discomfort in the neck, shoulder and arms. But not all chest pains are signs of angina. ECG (electrocardiograph) helps in tracing heart activity. Exercise-ECG assesses your heart condition when you are on a treadmill. Beta-blocker drugs help prevent angina pain. Potassium channel blockers and calcium channel blockers aid in improving blood flow to the coronary arteries. Glyceryl Trinitrate or GTN tablets work instantaneously by relaxing blood vessels and easing the blood flow to the heart muscles. Aspirin is prescribed to reduce the probability of blood clots and reducing blood viscosity. Statin medicines are prescribed to reduce cholesterol levels. Angioplasty involves passing a tiny balloon into a large artery and then blowing it up inside to widen the artery. Bypass surgery is done to bypass the narrowed section of arteries and provide the heart with blood vessels that are not obstructed. Angina can be controlled with medication and lifestyle changes in diet and exercise.
Cardiac catheterization is a test which is performed to obtain certain diagnostic information about the heart. Patients may require this medical therapy rather than undergo angioplasty or bypass surgery when they suffer from rare or easily controlled episodes of angina. Alternatively, cardiac catheterization is not performed in patients who have infrequent episodes of angina and in whom angina can be easily controlled. When a patient has heart failure due to suspected coronary artery disease or there is suspected coronary artery disease, cardiac catheterization is conducted. Cardiac catheterization can help:
The patient is asked not to drink or eat anything, except a small amount of water, for at least 6 to 12 hours before the test. The patient is tested for allergy to iodine or other medications. Patients suffering from kidney disease or diabetes or bleeding disorders must keep the cardiologist informed. The cardiac catheterization test is performed in a cath lab by a cardiologist. The actual catheterization procedure takes about 15 - 30 minutes. The patient's electrocardiogram that continuously records the electrical activity of the heart is taken.
A pulse oximeter device that measures the oxygen levels of the patients' blood is monitored. An intravenous needle is inserted into the patients' vein to give fluids or medicine during the catheterization procedure. A sedative is also given through this IV line which helps the patient to relax.
Cardiac catheterization procedure involves passing a catheter, a thin flexible tube, into the right or left side of the heart. The doctor inserts this thin plastic tube into the groin - femoral artery. Other places where in the catheter may be inserted are the elbow- brachial artery or the wrist - radial artery. From there it is slowly advanced into the chambers of the heart or into the coronary arteries. The doctor watches the progress of the catheter into the heart's vessels and chambers on the imaging screen. Pressures within the heart chambers are measured and the blood and tissue samples are also removed through the catheter. A small amount of dye is also injected through the catheter into the heart chamber or into one of the coronary arteries.
Therapeutic catheterization: Certain types of heart defects can be repaired using catheterization. For instance, if the coronary arteries are blocked, the cardiologist can use a catheter, guide wire and balloon to open and improve blood flow to the heart. This is termed as percutaneous coronary intervention (PCI).
Normal result indicate that there is no significant narrowing or blockage in the coronary arteries. Abnormal results may suggest that the heart does not pump blood normally or the valves in the heart may be weak. There may be leakage between heart chambers. There is a possibility of aortic aneurysm. Some complications with cardiac catheterization include heart attack or stroke, hematoma, puncture of the heart or arrhythmia.
Calcium Channel Blockers
Calcium channel blockers are one of the key drugs administered in cardiovascular conditions. In most cases they are used in case of hypertension and angina.They are classified depending upon their mode of action and their chemical composition. These chemicals when induced in the body block the calcium channels in the cell membrane.
They are selected for vascular sites rather than the myocardial region. These drugs facilitate good vasodilator effects with limited electro physiological effect on the cardiac conduction system pertaining to the AV and SA nodes. Thus the negative inotropic effects do not occur in these drugs.These drugs are more selective to the cerebral arteries than the systemic arteries. Eg: Nifedepine, Amlodipine, nimodipine.
These drugs cause peripheral vasodilation with a moderate inotropic effect. Subsequently they increase the coronary vasodilation. Cardiac rate may or may not increase as it causes a slight depression in the SA or AV nodal conduction route. Eg: Verapamil.
These drugs are also associated with peripheral vasodilation causing mild inotropic effect and minimum depression in the SA / AV node conduction. They increase coronary vasodilation. They also exhibit intermediate vaso-selectivity. Eg: Diltiazem.
The elimination route for most of these drugs is through the liver. In most cases the recommended dosage is twice a day for sustained release in the body. The limitation of calcium channel blockers administration for hypertension is often related to their functionality such as vasodilation. However, because of their mechanism of action and efficacy, they do not cause conditions such as reflex tachycardia.
Calcium channel blockers are given to children who have low renin levels. The drug is given with other drugs such as beta-blockers and diuretics to attain desired results of cardiac physiology. In most cases, calcium blocker administration requires investigative tests such as blood vessel abnormalities, liver and kidney function tests.
Side effects and precautions
Calcium channel blockers are known to have some side effects since they are closely associated with vascular physiology and cardiac conduction system. Syncope and presyncope episodes followed by dizziness are commonly-noticed side effects. This happens because of the decrease in blood pressure due to reduced heart rate. Arrhythmia is another potential side effect along with gastro-esophageal reflux and nausea.
Lower extremity swelling or edema is a complication of treatment with calcium channel blockers (especially with Felodipine and Amlodipine), Thioglitazones and Minoxidil. Transient Incontinence is another symptom noticed with Calcium Channel Blocker drugs.
The most common side effects of calcium channel blockers are peripheral edema, Bradycardia, headache and constipation in some cases. The dihydropyridine agents such as Nifedipine, Nicardipine, Isradipine, Felodipine, Nisoldipine and Amlodipine, can produce symptoms of vasodilation - specifically headaches, palpitations, flushing and peripheral edema or swelling in lower extremities.
Some studies indicate that juices such as grapefruit should be avoided during the administration of calcium channel blockers as they hinder with the drug absorption and breakdown in the system. Alcohol consumption must also be avoided as it may cause damage because of hepatic involvement in the respective drug.
Calcium channel blockers are taken as second line cardiac drugs with respect to anti-hypertensive drugs and beta-blockers. However careful examination of the patient drug history is performed before recommending these drugs because some studies also imply that prolonged usage of all three drugs may increase the incidence of diabetes and the risks associated with it. Drug evaluation is essential because recent studies indicate the involvement of clarithromycin along with calcium channel blockers causing kidney damage and prolonged usage of these drugs can also cause breast cancer in women.
Bibliography / Reference
Collection of Pages - Last revised Date: September 19, 2018