cardiac catheterization (redirected from Left-sided cardiac catheterization)

Cardiac Catheterization 

Definition

Cardiac catheterization (also called heart catheterization) is a diagnostic procedure which does a comprehensive examination of how the heart and its blood vessels function. One or more catheters is inserted through a peripheral blood vessel in the arm (antecubital artery or vein) or leg (femoral artery or vein) with x-ray guidance. This procedure gathers information such as adequacy of blood supply through the coronary arteries, blood pressures, blood flow throughout chambers of the heart, collection of blood samples, and x rays of the heart's ventricles or arteries.

A test that can be performed on either side of the heart, cardiac catheterization checks for different functions in both the left and right sides. When testing the heart's right side, tricuspid and pulmonary valve function are evaluated, in addition to measuring pressures of and collecting blood samples from the right atrium, ventricle, and pulmonary artery. Left-sided heart catheterization is performed by way of a catheter through an artery which tests the blood flow of the coronary arteries, function of the mitral and aortic valves, and left ventricle.

Purpose

The primary reason for conducting a cardiac catheterization is to diagnose and manage persons known or suspected to have heart disease, a frequently fatal condition that leads to 1.5 million heart attacks annually in the United States.

Symptoms and diagnoses that may lead to performing this procedure include:

• chest pain, characterized by prolonged heavy pressure or a squeezing pain
• abnormal treadmill stress test
• myocardial infarction, also known as a heart attack
• congenital heart defects, or heart problems that originated from birth
• a diagnosis of valvular-heart disease
• a need to measure the heart muscle's ability to pump blood

Typically performed along with angiography, a technique of injecting a dye into the vascular system to outline the heart and blood vessels, a catheterization can aid in the visualization of any blockages, narrowing, or abnormalities in the coronary arteries. If these signs are visible, the cardiologist may assess the patient's need and readiness for coronary bypass surgery, or perhaps a less invasive approach, such as dilation of a narrowed blood vessel either surgically or with the use of a balloon (angioplasty).

When looking at the left side of the heart, fluoroscopic guidance also allows the following diagnoses to be assessed:

• enlargement of the left ventricle
• ventricular aneurysms (abnormal dilation of a blood vessel)
• narrowing of the aortic valve
• insufficiency of the aortic or mitral valve
• the detour of blood from one side of the heart to the other due to septal defects (also known as shunting)

Precautions

Cardiac catheterization is categorized as an "invasive" procedure which involves the heart, its valves, and coronary arteries, in addition to a large artery in the arm or leg. Due to the nature of the test, it is important to evaluate for the following conditions before considering this procedure:

• A diagnosis of a bleeding disorder, poor kidney function, or debilitation. Any of these pre-existing conditions typically raises the risk of the catheterization procedure and may be reason to cancel the procedure.
• A diagnosis of heart valve disease. If this is detected, antibiotics may be given before the test to prevent inflammation of the membrane which lines the heart (endocarditis).

Description

To understand how a cardiac catheterization is able to diagnose and manage heart disease, the basic workings of the heart muscle must also be understood. Just as the body relies on a constant supply of blood to aid in its everyday functions, so does the heart. The heart is made up of an intricate web of blood vessels (coronary arteries) that ensure an adequate supply of blood rich in oxygen and nutrients. It is easy to see how an abnormality in any of these arteries can be detrimental to the heart's function. These abnormalities cause the heart's blood flow to decrease and result in the condition known as coronary artery disease or coronary insufficiency.

Catheterization is a valuable tool in detecting and treating abnormalities of the heart. Through the use of fluoroscopic (x ray) guidance, a catheter, which may resemble a balloon-tipped tube, is strung through the veins or arteries into the heart, so the cardiologist can monitor a body's various functions at each moment.

Generally a test that lasts two to three hours, a patient should expect the following prior to and during the catheterization procedure:

• A mild sedative may be given that will allow the patient to relax but remain conscious during the test.
• An intravenous needle will be inserted in the arm to administer medication. Electrodes will be attached to the chest to enable the painless procedure known as an electrocardiograph.
• Prior to inserting a catheter into an artery or vein in the arm or leg, the incision site will be made numb by injecting a local anesthetic. When the anesthetic is injected it may feel like a pin-prick followed by a quick stinging sensation. Pressure may also be experienced as the catheter travels through the blood vessel.
• After the catheter is guided into the coronary-artery system, a dye (also called a radiocontrast material) is injected to aid in the identification of any abnormalities of the heart. During this time, the patient may experience a hot, flushed feeling or a quickly passing nausea. Coughing or breathing deeply aids in any discomfort.
• Medication may be given during the procedure if chest pain is experienced, and nitroglycerin may also be administered to allow expansion of the heart's blood vessels.
• When the test is complete, the physician will remove the catheter and close the skin with several sutures or tape.

Preparation

Prior to the cardiac catheterization procedure, it is important to relay information to the physician or nurse regarding allergies to shellfish (such as shrimp or scallops) which contain iodine, iodine itself, or the dyes that are commonly used in other diagnostic tests.

Because this procedure is categorized as a surgery, the patient will be instructed not to eat or drink anything for at least six hours prior to the test. Just before the test begins, the patient will urinate and change into a hospital gown, then lie flat on a padded table that may also be tilted in order for the heart to be examined from a variety of angles.

Aftercare

While cardiac catheterization may be performed on an out-patient basis, a patient may require close monitoring following the procedure while remaining in the hospital for at least 24 hours. The patient will be instructed to rest in bed for at least eight hours immediately after the test. If the catheter was inserted into a vein or artery in the leg or groin area, the leg will be kept extended for four to six hours. If a vein or artery in the arm was used to insert the catheter, the arm will need to remain extended for a minimum of three hours.

The patient should expect a hard ridge to form over the incision site that diminishes as the site heals. Bluish discoloration under the skin at the point of insertion should also be expected but fades in two weeks. It is also not uncommon for the incision site to bleed during the first 24 hours following surgery. If this should happen, the patient should apply pressure to the site with a clean tissue or cloth for 10-15 minutes.

Aftercare

(Illustration by Argosy Inc.)

Risks

Similar to all surgical procedures, the cardiac catheterization test does involve some risks. Complications that may occur during the procedure include

• cardiac arrhythmias (an irregular heart beat)
• pericardial tamponade (a condition that causes excess pressure in the pericardium which affects the heart due to accumulation of excess fluid)
• the rare occurrence of myocardial infarction (heart attack) or stroke may also develop due to clotting or plaque rupture of one or more of the coronary or brain arteries.

Before left-side catheterization is performed, the anticoagulant medication heparin may be administered. This drug helps decrease the risk of the development of a blood clot in an artery (thrombosis) and blood clots traveling throughout the body (embolization).

The risks of the catheterization procedure increase in patients over the age of 60, those who have severe heart failure, or persons with serious valvular heart disease.

Normal results

Normal findings from a cardiac catheterization will indicate no abnormalities of heart chamber size or configuration, wall motion or thickness, the direction of blood flow, or motion of the valves. Smooth and regular outlines on the x ray indicate normal coronary arteries.

An essential part of the catheterization is measuring intracardiac pressures, or the pressure in the heart's chambers and vessels. Pressure readings that are higher than normal are significant for a patient's overall diagnosis. The pressure readings that are lower, other than those which are produced as a result of shock, typically are not significant.

An ejection fraction, or a comparison of how much blood is ejected from the heart's left ventricle during its contraction phase with a measurement of blood remaining at the end of the left ventricle's relaxation phase, is also determined by performing a catheterization. The cardiologist will look for a normal ejection fraction reading of 60-70%.

Abnormal results

Cardiac catheterization provides valuable still and motion x-ray pictures of the coronary arteries that help in diagnosing coronary artery disease, poor heart function, disease of the heart valves, and septal defects (a defect in the septum, the wall that separates two heart chambers).

The most prominent sign of coronary artery disease is the narrowing or blockage in the coronary arteries, with narrowing that is greater than 70% considered significant. A clear indication for intervention (by angioplasty or surgery) is a finding of significant narrowing of the left main coronary artery and/or blockage or severe narrowing in the high, left anterior descending coronary artery.

A finding of impaired wall motion is an additional indicator of coronary artery disease, aneurysm, an enlarged heart, or a congenital heart problem. Using the findings from an ejection fraction test which measures wall motion, cardiologists look at an ejection fraction reading under 35% as increasing the risk of complications while also decreasing a successful long term or short term outcome with surgery.

Detecting the difference in pressure above and below the heart valve can verify heart valve disease. The greater narrowing correlates with the higher pressure difference.

To confirm septal defects, a catheterization measures oxygen content on both the left and right sides of the heart. The right heart pumps unoxygenated blood to the lungs, and the left heart pumps blood that contains oxygen from the lungs to the rest of the body. Right side elevated oxygen levels indicate left-to-right atrial or ventricular shunt. A left side that experiences decreased oxygen indicates a right-to-left shunt.

Resources

Organizations

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.

National Heart, Lung and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov.

Key terms

Aneurysm — An abnormal dilatation of a blood vessel, usually an artery. It can be caused by a congenital defect or weakness in the vessel's wall.

Angiography — In cardiac catheterization, a picture of the heart and coronary arteries is seen after injecting a radiopaque substance (often referred to as a dye) throughout the veins and arteries.

Angioplasty — An alternative to vascular surgery, a balloon catheter is used to mechanically dilate the affected area of the artery and enlarge the constricted or narrowed segment.

Aortic valve — The valve between the heart's left ventricle and ascending aorta that prevents regurgitation of blood back into the left ventricle.

Catheter — A tube made of elastic, elastic web, rubber, glass, metal, or plastic used to evacuate or inject fluids into the body. In cardiac catheterization, a long, fine catheter is used for passage through a blood vessel into the chambers of the heart.

Coronary bypass surgery — A surgical procedure which places a shunt to allow blood to travel from the aorta to a branch of the coronary artery at a point past an obstruction.

Left anterior descending coronary artery (LAD) — One of the heart's coronary artery branches from the left main coronary artery which supplies blood to the left ventricle.

Mitral valve — The bicuspid valve which is between the left atrium and left ventricle of the heart.

Pulmonary valve — The heart valve which is positioned between the right ventricle and the opening into the pulmonary artery.

Shunt — A passageway (or an artificially created passageway) that diverts blood flow from one main route to another.

Tricuspid valve — The right atrioventricular valve of the heart.

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catheterization /cath·e·ter·iza·tion/ (kath″ĕ-ter-ĭ-za´shun) passage of a catheter into a body channel or cavity.

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cardiac catheterization  passage of a small catheter through a vein in an arm or leg or the neck and into the heart, permitting the securing of blood samples, determination of intracardiac pressure, detection of cardiac anomalies, planning of operative approaches, and determination, implementation, or evaluation of appropriate therapy.

retrograde catheterization  passage of a cardiac catheter against the direction of blood flow and into the heart.

transseptal catheterization  passage of a cardiac catheter through the right atrium into the left atrium, performed to relieve valve obstruction and in techniques such as balloon mitral valvuloplasty.

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cardiac catheterization,

a diagnostic procedure in which a catheter is introduced through an incision into a large vein, usually of an arm or a leg, and threaded through the circulatory system to the heart.

method The sterile radiopaque catheter 100 to 125 cm in length ultimately reaches the superior vena cava, and then into the right atrium (or through an artery leading to the left ventricle) and other structures to be studied. The course of the catheter is followed with fluoroscopy, and radiographs may be taken. An electrocardiogram is monitored on an oscilloscope. As the catheter tip passes through the chambers and vessels of the heart, blood pressure is monitored, and blood samples are taken to study the oxygen content.

nursing intervention An antibiotic is often given the day before the procedure. Cardiac catheterization takes from 1 to 3 hours: the patient has to lie still but may be asked to cough or breathe deeply during the procedure. It is anxiety producing, and the patient needs explanation and emotional support. A young child may need a sedative. The pulse on the operative side and the blood pressure on the other side of the body are monitored at least every 15 minutes for 1 hour and every half hour thereafter. During left heart catheterization, peripheral pulses are also monitored. The temperature may be elevated for several hours, and there may be pain at the incision site. The patient is prevented from bending the hip on the operative side after the study. A sand bag or other counterpressure dressing is applied to the site to prevent bleeding at the insertion site. The nurse observes the site for bleeding and for signs of infection, thrombophlebitis, and cardiac arrhythmia. Cardiac catheterization is typically performed by a special team in a special laboratory. By offering information and counseling, a member of the team may be of great help to the patient before and after the procedure.

outcome criteria Many conditions may be accurately identified and assessed by using cardiac catheterization, including congenital heart disease, coronary artery disease, tricuspid stenosis, and valvular incompetence. Among the risks of the procedure are local infection, cardiac arrhythmia, and thrombophlebitis.

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cardiac

1. pertaining to the heart. See also heart.

2. pertaining to the gastric cardia.

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cardiac afterload

the impedance to ventricular emptying presented by aortic pressure.

cardiac area

see precordium.

cardiac biopsy

an uncommon clinical procedure. May be performed via thoracotomy or with a biopsy catheter introduced intravenously.

cardiac catheterization

the insertion of a catheter into a vein or artery and guiding it into the interior of the heart for purposes of measuring cardiac output, determining the oxygen content of blood in the heart chambers, and evaluating the structural components of the heart.

cardiac compensation

in cardiac disease the compensation for the inefficiency of the heart's pump action by enlisting the various reserves of the heart such as hypertrophy, enlargement, increase in rate, so as to maintain circulatory equilibrium and prevent the appearance of signs of congestive heart failure.

cardiac compression

an emergency measure to empty the ventricles of the heart in an effort to circulate the blood, and also to stimulate the heart so that it will resume its pumping action. Involves the application of pressure through the thoracic wall. More commonly used in animals than other forms of cardiac massage.

cardiac conducting cells

specialized cardiac fibers modified to conduct impulses from the A-V node via the septum to the ventricles. Called also Purkinje fibers.

cardiac conducting system

the cardiac tissue responsible for electrical conduction, made up of the sinoatrial node, the atrioventricular node, and the atrioventricular bundle and cardiac conducting fibers.

cardiac depressor nerve

a branch of the vagus nerve composed of afferent nerve fibers which arise around the base of the heart; called also aortic nerve.

cardiac dilatation

the heart volume is increased but the effective mass of cardiac muscle is not. A dilated heart has lost some of its reserve.

cardiac dullness

the area of the chest wall over which a dull sound, indicating the position of the heart, can be elicited by percussion.

cardiac failure

see heart failure.

cardiac fibrillation

see ventricular fibrillation.

cardiac fibrosis

see cardiac cirrhosis.

cardiac flow load

the work required of the heart can be increased by a need for an increased flow rate of blood, e.g. when there is an anastomosis, congenital arteriovenous defect, portosystemic shunt.

cardiac function curves

statistical curves used in modeling the cardiovascular functions, relating e.g. venous return to cardiac output.

cardiac glands

in the cardiac region of the gastric wall; branched, tubular, coiled, mucus-secreting.

cardiac glycosides

the glycosides of Digitalis purpurea (digitoxin, gitalin and gitoxin) and digoxin (from D. lanata). Strophanthin and ouabain are glycosides found in Strophanthus spp. Other cardiac glycosides are present in the skin of toads (Bufo maritimus, B. vulgaris), but are of toxicological rather than therapeutic interest.

cardiac horse sickness

see african horse sickness.

cardiac hypertrophy

enlargement of the heart coincident with an increase in muscle mass; an indication of response to an increase in load which may or may not be associated with disease. It is an expression of cardiac compensation but some of the cardiac reserve has been lost.

cardiac impulse

see cardiac impulse. Called also apex beat.

cardiac index

cardiac output divided by the animal's body surface area in m². The normal range for dogs is 1.8-3.5 l/m².

left-sided cardiac enlargement

may involve either the left ventricle or atrium, or both, and can be demonstrated on radiographs and electrocardiography. Seen most commonly in mitral valvular disease in dogs.

cardiac massage

manual massage of the heart or stimulation with an electrical current through an open thoracic wall. The term is sometimes used interchangeably with cardiac compression.

cardiac mucosa

the most cranial of the gastric mucosae; secretes only mucus, except in pigs, in which the area covered by this mucosa is much larger than in the other species and bicarbonate is also secreted.

cardiac murmur

see heart murmur.

cardiac output

the volume of blood pumped per unit of time. May be calculated by oxygen consumption measurement or determined by dilution of indocyanine green or cold saline, using catheters with thermistors placed intravenously (thermodilution method). It can be estimated clinically by measuring heart rate, pulse quality or pressure, and assessment of tissue perfusion, e.g. capillary refill time.

cardiac pacing

employing cardiac pacemakers to control heart rate.

cardiac preload

ventricular end-diastolic volume.

cardiac pressure load

the stress of working against an elevated blood pressure in the arterial circuit; one of the two major groups of causes of heart disease; the other is flow load.

cardiac racing syndrome

a disease of companion birds manifested by a sudden increase in heart rate, up to 1000/min, in the period immediately after being restrained. Death occurs within a few seconds.

cardiac reserve

the reserve mechanisms in the heart to compensate for defects which could make the heart's pumping action ineffective. The reserve mechanisms include hypertrophy, enlargement, increase in heart rate and an increase in stroke volume, a result of the increase in muscle mass and the enlargement of the ventricles.

right-sided cardiac enlargement

may involve either the right ventricle or atrium. Occurs in heartworm disease in dogs.

cardiac rupture

penetration of the myocardium by a reticular foreign body in cows, or rupture of a patch of chronic fibrotic myocarditis in horses, causes cardiac tamponade and sudden death.

cardiac size

may increase as a result of hypertrophy, dilatation or a combination of the two. A common belief with some scientific support is that performance of horses in sprint races is closely related to heart size.

cardiac stroke volume

the amount of blood ejected with each systole.

cardiac thrill

see thrill.

cardiac valve fenestration

the valve surface is incomplete, creating a lattice effect; mostly congenital defects in foals.

cardiac valve hematocysts

congenital, blood-filled cysts on the atrioventricular valves considered to be of no pathogenic significance.

cardiac valve laceration

tearing of the valve tissue or attachment to myocardium may occur spontaneously or as a sequel to endocarditis; adds a significant additional flow load to the heart.

cardiac valve rupture

see cardiac valve laceration (above).

cardiac valves

heart valves formed by evaginations of the cardiac and vascular endothelium supported by connective tissue; includes atrioventricular and semilunar valves on both sides of the heart.

cardiac valvular disease

see valvular disease.

cardiac vascular shunts

includes patent foramen ovale, ventricular septal defect, tetralogy of Fallot, patent ductus arteriosus.

cardiac work

includes effective work—that needed for the onward propulsion of blood through the correct channels against arterial pressure, total work—includes all of the work performed by the heart including some involved in moving blood in the wrong direction.

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cardiac catheterization

Cardiology A procedure in which a flexible catheter is inserted in a peripheral blood vessel, usually a leg–femoral or arm—antecubital vein, passed through the inferior vena cava and, under fluoroscopic guidance, placed in the region(s) of interest Complications Arrhythmias, embolism–cerebral, pulmonary, MI, pericardial tamponade. See Doppler echocardiography

Cardiac catheterization indications

Evaluate heart valves and detect stenosis and regurgitation Determine regional BP and detect pulmonary HTN Obtain blood samples to evaluate oxygenation of blood Inject dye and evaluate heart function in 'real time'–cardiac angiography and assess patency of the coronary arteries–coronary angiography.

Right-sided cardiac catheterization

Evaluate tricuspid and pulmonary valve function, and measure pressures of and take blood samples from the right atrium and ventricle, and pulmonary artery Abnormalities, right side: Pulmonary HTN, pulmonary valve stenosis, tricuspid valve stenosis, atrial and ventricular septal defects

Left-sided cardiac catheterization

Evaluate function of mitral and aortic valves, and coronary arteries Abnormalities, left side Aortic valve regurgitation, CAD–stenosis or occlusion, mitral valve stenosis or regurgitation, ventricular hypertrophy or aneurysm