There is some test to diagnose disease, injury, congenital and acquired abnormalities of the heart. This article is useful for nurses to prepare and understanding cardiac diagnostic tests. Here we provide some of the test detail to diagnose heart and blood vessel disease. The Tests Type and description are given below. Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease
A. Cardiac enzymes
1. CK-MB (creatine kinase, myocardial muscle)
An elevation in value indicates myocardial damage. An elevation occurs within hours and peaks at 18 hours following an acute ischemic attack. Normal value is 0% to 5% of total; total CK is 26 to 174 units/L.
2. Lactate dehydrogenase (LDH)
Elevations in LDH levels occur 24 hours flowing myocardial infarction and peak in 48 to 72 hours. Normally, LDH1 is lower than LDH2; when the serum concentration of LDH1 is higher than LDH2, the pattern is indicated as “flipped,” signifying myocardial necrosis.
The normal value of LDH in conventional units is 140 to 280 international units/L.
Troponin is composed of three proteins—troponin C, cardiac troponin I, and cardiac troponin T. Troponin I especially has a high affinity for myocardial injury; it rises within 3 hours and persists for up to 7 to 10 days. Normal values are low, with troponin I being lower than 0.6 ng/ml and troponin I normally ranging from 0 to 0.2 ng/ml; thus any rise can indicate myocardial cell damage. Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease
myoglobin is an oxygen-binding protein found in cardiac and skeletal muscle. the level rises within two hours after cell death, with a rapid decline in the level after 7 hours.
Complete blood count
The red blood cell count decreases in rheumatic heart disease and infective endocarditis and increases in conditions characterized by inadequate tissue oxygenation. The white blood cell count increase in infectious and inflammatory diseases of the heart and after
myocardial infarction (MI) because large numbers of white blood cells are needed to dispose of the necrotic tissue resulting from the infarction. An elevated hematocrit level can result from vascular volume depletion. Decreases in hemoglobin and hematocrit levels can indicate anemia. Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease
Blood coagulation factors
An increase in coagulation factor can occur during and after MI, which places the client at greater risk for thrombophlebitis and extension of clots in the coronary arteries.
1. The lipids profile measures serum cholesterol, triglyceride, and lipoprotein levels.
2. The lipid profile is used to assess the risk of developing coronary artery disease.
3. The desirable range for serum cholesterol is lower than 200mg/dl, with low-density lipoprotein cholesterol
lower than 130mg/dl and high-density lipoprotein cholesterol at 30 to 70 mg/dl.
4. Lipoprotein – aorLp(a), a modified form of LDL, increases atherosclerotic plaques and increases clots;
the value should be less than 30mg/dl.
E.Homocysteine: elevated levels may increase the risk of cardiovascular disease; the level should be less than 14 mmol/dl.
F. Highly sensitive C-reactive protein (hsCRP): Detects an inflammatory process such as that associated with the
development of atherothrombosis; a level less than 1 mg/dl is considered low risk and level over 3mg/dl place the
client at high risk for heart disease.
G. Microalbuminuria: A Small amount of protein in the urine has been a marker for endothelial dysfunction in cardiovascular disease. Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease
- Hypokalemia causes increased cardiac electrical instability, ventricular dysrhythmias, and increased risk of digoxin toxicity.
- In hypokalemia, the electrocardiogram shows flattening and inversion of the T wave, the appearance of a U wave, and ST depression.
- Hyperkalemia causes asystole and ventricular dysrhythmias.
- In hyperkalemia, the electrocardiogram may show tall peaked T waves, widened QRS complexes, prolonged PR intervals, or flat P waves.
- The serum sodium level decreases with the use of diuretics.
- The serum sodium level decreases in heart failure; including water excess.
Hypocalcemia can cause ventricular dysrhythmias, prolonged ST and QT intervals, and cardiac arrest. Hypercalcemia can cause a shortened ST segment and sidelined I wave, atrioventricular block tachycardia or bradycardia, digitalis hypersensitivity, and cardiac arrest.
Phosphorus levels should be interpreted with calcium level because the kidneys retain or excrete one electrolyte in an inverse relationship to the other.
A low magnesium level can cause ventricular tachycardia and fibrillation. Electrocardiographic changes that may be observed with hypomagnesemia include tall T waves a depressed ST segment. A high magnesium level can cause muscle weakness, hypotension, and bradycardia. Electrocardiographic changes that may be observed with hypermagnesemia include a prolonged PR interval and widened QRS complex Electrolyte and mineral imbalance can cause cardiac electrical instability that can result in life-threatening dysrhythmias.
Blood urea nitrogen
The blood urea nitrogen level is evlevated in heart disorders that adversely affect renal circulation, such as heart failure and cardiogenic shock.
An acute cardiac episode can elevate the blood glucose level. Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease
B-type natriuretic peptide (BNP)
BNP is released in response to atrial and ventricular stretch; it serves as a marker for congestive heart failure (CHF). BNP levels should be lower than 100 pg/mL; the higher the level, the more severe the CHF/
Radiography of the chest is done to determine the size, silhouette, and position of the heart. Specific pathological changes are difficult to determine on x-rays, but anatomical changes can be seen.
This common noninvasive diagnostic test records the electrical activity of the great and is useful for detecting cardiac dysrhythmias, location and extent of MI, and cardiac hypertrophy and for evaluation of the effectiveness of cardiac medications.
In this noninvasive test, the client wears a Holter monitor and an electrocardiographic tracing is recorded continuously over a period of 24 hours or more while the client performs his or her activities of daily living. The Holter monitor identifies dysrhythmias if they occur and evaluates the effectiveness of antidysrhythmics or pacemaker therapy.
This non-invasive procedure is based on the principles of ultrasound and evaluates structural and functional changes in the heart. Heart chamber size is measured, ejection fraction is calculated, and the flow gradient across the valves is determined.
Transesophageal echocardiography may be performed in which the echocardiogram is done through the esophagus; this is an invasive exam and requires pre- and post-procedure preparation and care similar to endoscopy procedures.
Exercise electrocardiography testing (stress test)
- This noninvasive test studies the heart during activity and detects and evaluates coronary artery disease.
- Treadmill testing is the most commonly used mode of stress testing.
- Stress testing may be used with myocardial radionuclide testing, at which point the procedure becomes invasive because a radionuclide must be injected.
- If the client is unable to tolerate the exercise, an intravenous (IV) infusion of dipyridamole, dobutamine hydrochloride, or adenosine is given to dilate the coronary arteries and simulate the effect of exercise.
- Informed consent is required if a radionuclide is injected.
- Obtain informed consent if required.
- Provide adequate rest the night before the procedure.
- client to eat a light meal 1 to 2 hours before the procedure.
- Instruct the client to avoid smoking, alcohol, and caffeine before the procedure.
- Instruct the client to ask the physician about taking prescribed medication on the day of the procedure; theophylline products are usually withheld 12 hours before the test and calcium channel blockers and b-blockers are usually held for 24 hours.
- Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease pdf
Digital subtraction angiography
This test combines x-ray techniques and a computerized subtraction technique with fluoroscopy for visualization of the cardiovascular system. A contrast medium (dye) is injected.
Myocardial nuclear perfusion imaging (MNPI)
Nuclear cardiology is the use of radionuclide techniques and scanning for cardiovascular assessment. The most common tests include technetium pyrophosphate scanning, thallium imaging, and multi gated cardiac blood pool imaging; can evaluate cardiac motion and calculate the ejection fraction. Cardiac Diagnostic Tests and Procedures To Diagnose Heart Disease
Magnetic resonance imaging (MRI)
This is a noninvasive diagnostic test that produces an image of the heart or great vessels through the interaction of magnetic fields, radio waves, and atomic nuclei. It provides information on chamber size and thickness valve and ventricular function and blood flow through the great vessels and coronary arteries.
An invasive test involving the insertion of a catheter into the heart and surrounding vessels. Obtains information about the structure and performance of the heart chambers and valves and the coronary circulation.
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