Coronary catheterization - AbsoluteAstronomy.com

A coronary catheterization is a minimally invasive procedure to access the coronary circulation

Coronary circulation

Coronary circulation is the circulation of blood in the blood vessels of the heart muscle . The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries...

and blood filled chambers of the heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

using a catheter

Catheter

In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...

. It is performed for both diagnostic and interventional (treatment) purposes.

Coronary catheterization is one of the several cardiology diagnostic tests and procedures

Cardiology diagnostic tests and procedures

The diagnostic tests in cardiology are methods of identifying heart conditions associated with healthy vs. unhealthy, pathologic, heart function.-History:...

. Specifically, coronary catheterization is a visually interpreted test performed to recognize occlusion

Vascular occlusion

Vascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...

, stenosis

Stenosis

A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....

, restenosis

Restenosis

Restenosis literally means the reoccurrence of stenosis, a narrowing of a blood vessel, leading to restricted blood flow. Restenosis usually pertains to an artery or other large blood vessel that has become narrowed, received treatment to clear the blockage and subsequently become renarrowed...

, thrombosis

Thrombosis

Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...

or aneurysm

Aneurysm

An aneurysm or aneurism is a localized, blood-filled balloon-like bulge in the wall of a blood vessel. Aneurysms can commonly occur in arteries at the base of the brain and an aortic aneurysm occurs in the main artery carrying blood from the left ventricle of the heart...

al enlargement of the coronary artery lumen

Lumen (anatomy)

A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...

s; heart chamber

Heart chamber

aHeart chamber is a general term used to refer to any chambers of the mammalian heart. The heart consists of four chambers: the right and left atrium and the right and left ventricle. The top chambers are connected to the bottom chambers by valves and are separated by the coronary sulcus...

size; heart muscle contraction performance; and some aspects of heart valve

Heart valve

A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...

function. Important internal heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

and lung

Lung

The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

blood pressure

Blood pressure

Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

s, not measurable from outside the body, can be accurately measured during the test. The relevant problems that the test deals with most commonly occur as a result of advanced atherosclerosis

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

– atheroma

Atheroma

In pathology, an atheroma is an accumulation and swelling in artery walls that is made up of macrophage cells, or debris, that contain lipids , calcium and a variable amount of fibrous connective tissue...

activity within the wall of the coronary arteries

Artery

Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....

. Less frequently, valvular

Heart valve

A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...

, heart muscle, or arrhythmia issues are the primary focus of the test.

Coronary artery luminal narrowing

Stenosis

A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....

reduces the flow reserve for oxygenated blood to the heart, typically producing intermittent angina. Very advanced luminal occlusion

Vascular occlusion

usually produces a heart attack

Myocardial infarction

Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

. However, it has been increasingly recognized, since the late 1980s, that coronary catheterization does not allow the recognition of the presence or absence of coronary atherosclerosis

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

itself, only significant luminal changes which have occurred as a result of end stage complications of the atherosclerotic

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

process. See IVUS and atheroma

Atheroma

for a better understanding of this issue.

History

The technique of angiography was first developed in 1927 by the Portuguese physician Egas Moniz

Egas Moniz

António Caetano de Abreu Freire Egas Moniz , known as Egas Moniz , was a Portuguese neurologist and the developer of cerebral angiography...

at the University of Lisbon to provide contrasted x-ray in order to diagnose nervous diseases, such as tumors, coronary heart disease and arteriovenous malformations. He is recognized as one of the pioneers in this field.

Coronary catheterization was further explored in 1929 when the German physician Werner Forssmann

Werner Forssmann

Werner Theodor Otto Forßmann, was a physician from Germany who shared the 1956 Nobel Prize in Medicine for developing a procedure that allowed for cardiac catheterization. In 1929, he put himself under local anesthetic and inserted a catheter into his own arm...

inserted a plastic tube in his cubital vein and guided it to the right chamber of the heart. He took an x-ray to prove his success and published it on November 5 1929 with the title "Über die Sondierung des rechten Herzens" (About probing of the right heart).
The coronarography of the left heart was introduced in 1953 with the report by a Portuguese group, published in Cardiologia, International Archives of Cardiology volume 22, pages 45–61, by E. Coelho et al., entitled "Arteriografia das coronárias no homem vivo/L'artériograpie des coronaires chez l'homme vivant" (arteriography of the coronaries in the living man). They were the first to non-selectively inject radiocontrast

Radiocontrast

Radiocontrast agents are a type of medical contrast medium used to improve the visibility of internal bodily structures in an X-ray based imaging techniques such as computed tomography or radiography...

in the coronary arteries.

In 1960 F. Mason Sones, a pediatric cardiologist at the Cleveland Clinic

Cleveland Clinic

The Cleveland Clinic is a multispecialty academic medical center located in Cleveland, Ohio, United States. The Cleveland Clinic is currently regarded as one of the top 4 hospitals in the United States as rated by U.S. News & World Report...

, accidentally injected radiocontrast in a coronary artery instead of the left ventricle. Although the patient had a reversible cardiac arrest, Sones and Shirey developed the procedure further, and are credited with the discovery (Connolly 2002); they published a series of 1,000 patents in 1966 (Proudfit et al.).

Since the late 1970s, building on the pioneering work of Charles Dotter in 1964 and especially Andreas Gruentzig

Andreas Gruentzig

Andreas Roland Grüntzig was a German cardiologist who first developed successful balloon angioplasty for expanding lumens of narrowed arteries.-Angioplasties:...

starting in 1977, coronary catheterization has been extended to therapeutic uses: (a) the performance of less invasive physical treatment for angina and some of the complications of severe atherosclerosis

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

, (b) treating heart attack

Myocardial infarction

Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

s before complete damage has occurred and (c) research for better understanding of the pathology of coronary artery disease and atherosclerosis

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

.

In the early 1960s, cardiac catheterization frequently took several hours and involved significant complications for as many as 2–3% of patients. With multiple incremental improvements over time, simple coronary catheterization examinations are now commonly done more rapidly and with significantly improved outcomes.

Patient participation

The patient

Patient

A patient is any recipient of healthcare services. The patient is most often ill or injured and in need of treatment by a physician, advanced practice registered nurse, veterinarian, or other health care provider....

being examined or treated is usually awake during coronary catheterization, ideally with only local anaesthesia such as lidocaine

Lidocaine

Lidocaine , Xylocaine, or lignocaine is a common local anesthetic and antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic or as a local anesthetic for minor surgery.- History :Lidocaine, the first amino...

and minimal general sedation

Sedation

Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...

, throughout the procedure. Performing the procedure with the patient awake is safer as the patient can immediately report any discomfort or problems and thereby facilitate rapid correction of any undesirable events. Medical monitors fail to give a comprehensive view of the patient's immediate well-being; how the patient feels is often a most reliable indicator of procedural safety.

Death, myocardial infarction

Myocardial infarction

Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

, stroke

Stroke

A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

, serious ventricular arrhythmia, and major vascular complications each occur in less than 1% of patients undergoing catheterization. However, though the imaging portion of the examination is often brief, because of setup and safety issues the patient is often in the lab for 20–45 minutes. Any of multiple technical difficulties, while not endangering the patient (indeed added to protect the patient's interests) can significantly increase the examination time.

Equipment

Coronary catheterization is performed in a cardiac catheterization lab, usually located within a hospital. With current designs, the patient must lie relatively flat on a narrow, minimally padded, radiolucent

Radiodensity

Radiodensity refers to the relative inability of electromagnetic radiation, particularly X-rays, to pass through a particular material. Radiolucency indicates greater transparency or "transradiancy" to X-ray photons...

(transparent to X-ray

X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

) table. The X-Ray source and imaging camera equipment are on opposite sides of the patient's chest and freely move, under motorized control, around the patient's chest so images can be taken quickly from multiple angles. More advanced equipment, termed a bi-plane cath lab, uses two sets of X-Ray source and imaging cameras, each free to move independently, which allows two sets of images to be taken with each injection of radiocontrast agent. The equipment and installation setup to perform such testing typically represents a capital expenditure of US$2–5 million (2004), sometimes more, partially repeated every few years.

Diagnostic procedures

During coronary catheterization (often referred to as a cath by physicians), blood pressure

Blood pressure

s are recorded and X-Ray

X-ray

motion picture shadow-grams of the blood inside the coronary arteries are recorded. In order to create the X-ray pictures, a physician

Physician

A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...

guides a small tube-like device called a catheter, typically ~2.0 mm (6-French) in diameter, through the large arteries of the body until the tip is just within the opening of one of the coronary arteries. By design, the catheter is smaller than the lumen of the artery

Artery

Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....

it is placed in; internal/intraarterial blood pressures are monitored through the catheter

Catheter

to verify that the catheter does not block blood flow.

The catheter is itself designed to be radiodense

Radiodensity

for visibility and it allows a clear, watery, blood compatible radiocontrast agent, commonly called an X-ray dye, to be selectively injected and mixed with the blood flowing within the artery. Typically 3–8 cc of the radiocontrast agent is injected for each image to make the blood flow

Blood flow

Blood flow is the continuous running of blood in the cardiovascular system.The human body is made up of several processes all carrying out various functions. We have the gastrointestinal system which aids the digestion and the absorption of food...

visible for about 3–5 seconds as the radiocontrast agent is rapidly washed away into the coronary capillaries and then coronary vein

Vein

In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

s. Without the X-ray dye injection, the blood and surrounding heart tissues

Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

appear, on X-ray, as only a mildly-shape-changing, otherwise uniform water density mass; no details of the blood and internal organ structure are discernible. The radiocontrast within the blood allows visualization of the blood flow within the arteries or heart chambers, depending on where it is injected.

If atheroma

Atheroma

, or clots, are protruding into the lumen, producing narrowing

Stenosis

A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....

, the narrowing may be seen instead as increased haziness within the X-ray shadow images of the blood/dye column within that portion of the artery; this is as compared to adjacent, presumed healthier, less stenotic

Stenosis

A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....

areas. See the single frame illustration of a coronary angiogram image on the angioplasty

Angioplasty

Angioplasty is the technique of mechanically widening a narrowed or obstructed blood vessel, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated to a fixed size...

page.

For guidance regarding catheter positions during the examination, the physician mostly relies on detailed knowledge of internal anatomy, guide wire and catheter behavior and intermittently, briefly uses fluoroscopy

Fluoroscopy

Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an X-ray source and fluorescent screen between which a patient is placed...

and a low X-ray dose to visualize when needed. This is done without saving recordings of these brief looks. When the physician is ready to record diagnostic views, which are saved and can be more carefully scrutinized later, he activates the equipment to apply a significantly higher X-ray dose, termed cine

Çine

Çine is a town and a district of Aydın Province, in the Aegean region of Turkey, from the city of Aydın, on the road to Muğla.- Geography :Formerly known as Kıroba, Çine is an attractive rural district in the southern part of the valley of the Büyük Menderes River, on the southern flank of Madran...

, in order to create better quality motion picture images, having sharper radiodensity contrast, typically at 30 frames per second. The physician controls both the contrast injection, fluoroscopy

Fluoroscopy

and cine application timing so as to minimize the total amount of radiocontrast injected and times the X-Ray to the injection so as to minimize the total amount of X-ray used. Doses of radiocontrast agents and X-ray exposure times are routinely recorded in an effort to maximize safety.

Though not the focus of the test, calcification

Calcification

Calcification is the process in which calcium salts build up in soft tissue, causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification.-Causes:...

within the artery

Artery

Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....

walls, located in the outer edges of atheroma

Atheroma

within the artery walls, is sometimes recognizable on fluoroscopy (without contrast injection) as radiodense halo rings partially encircling, and separated from the blood filled lumen by the interceding radiolucent atheroma tissue and endothelial

Endothelium

The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...

lining. Calcification, even though usually present, is usually only visible when quite advanced and calcified sections of the artery wall happen to be viewed on end tangent

Tangent

In geometry, the tangent line to a plane curve at a given point is the straight line that "just touches" the curve at that point. More precisely, a straight line is said to be a tangent of a curve at a point on the curve if the line passes through the point on the curve and has slope where f...

ially through multiple rings of calcification, so as to create enough radiodensity to be visible on fluoroscopy.

Therapeutic procedures

By changing the diagnostic catheter to a guiding catheter, physicians can also pass a variety of instruments through the catheter and into the artery

Artery

Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....

to a lesion

Lesion

A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

site. The most commonly used are 0.014 inch (0.3556 mm) guide wires and the balloon dilation catheters.

By injecting radiocontrast agent through a tiny passage extending down the balloon catheter

Balloon catheter

A balloon catheter is a type of "soft" catheter with an inflatable "balloon" at its tip which is used during a catheterization procedure to enlarge a narrow opening or passage within the body...

and into the balloon, the balloon is progressively expanded. The hydraulic pressures are chosen and applied by the physician, according to how the balloon within the stenosis

Stenosis

A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....

responds. The radiocontrast filled balloon is watched under fluoroscopy (it typically assumes a "dog bone" shape imposed on the outside of the balloon by the stenosis as the balloon is expanded), as it opens. As much hydraulic brute force is applied as judged needed and visualized to be effective to make the stenosis of the artery lumen visibly enlarge.

Typical normal coronary artery pressures are in the <200 mmHg range (27 kPa). The hydraulic pressures applied within the balloon may extend to as high as 19000 mmHg (2,500 kPa). Prevention of over-enlargement is achieved by choosing balloons manufactured out of high tensile strength clear plastic membranes. The balloon is initially folded around the catheter, near the tip, to create a small cross-sectional profile to facilitate passage though luminal stenotic areas and designed to inflate to a specific pre-designed diameter. If over inflated, the balloon material simply tears and allows the inflating radiocontrast agent to simply escape into the blood.

Additionally, several other devices can be advanced into the artery via a guiding catheter. These include laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

catheters, stent

Stent

In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...

catheters, IVUS catheters, Doppler

Doppler echocardiography

Doppler echocardiography is a procedure which uses ultrasound technology to examine the heart. An echocardiogram uses high frequency sound waves to create an image of the heart while the use of Doppler technology allows determination the speed and direction of blood flow by utilizing the Doppler...

catheter, pressure or temperature measurement catheter and various clot and grinding or removal devices. Most of these devices have turned out to be niche devices, only useful in a small percentage of situations or for research.

Stents, which are specially manufactured expandable stainless steel mesh tubes, mounted on a balloon catheter, are the most commonly used device beyond the balloon catheter. When the stent/balloon device positioned within the stenosis, the balloon is inflated which, in turn, expands the stent and the artery. The balloon is removed and the stent remains in place, supporting the inner artery walls in the more open, dilated position. Current stents generally cost around $1,000 to 3,000 each (US 2004 dollars), the drug coated ones being the more expensive.

Advances in catheter based physical treatments

Interventional procedures have been plagued by restenosis due to the formation of endothelial

Endothelium

tissue

Biological tissue

overgrowth at the lesion site. Restenosis

Restenosis

is the body's response to the injury of the vessel wall from angioplasty

Angioplasty

and to the stent

Stent

as a foreign body

Foreign body

A foreign body is any object originating outside the body. In machinery, it can mean any unwanted intruding object.Most references to foreign bodies involve propulsion through natural orifices into hollow organs....

. As assessed in clinical trials during the late 1980 and 1990s, using only balloon angioplasty (POBA, plain old balloon angioplasty), up to 50% of patients suffered significant restenosis but that percentage has dropped to the single to lower two digit range with the introduction of drug-eluting stents. Sirolimus

Sirolimus

Sirolimus , also known as rapamycin, is an immunosuppressant drug used to prevent rejection in organ transplantation; it is especially useful in kidney transplants. A macrolide, sirolimus was first discovered as a product of the bacterium Streptomyces hygroscopicus in a soil sample from Easter...

, paclitaxel

Paclitaxel

Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. It was discovered in a U.S. National Cancer Institute program at the Research Triangle Institute in 1967 when Monroe E. Wall and Mansukh C. Wani isolated it from the bark of the Pacific yew tree, Taxus brevifolia and named it taxol...

and everolimus

Everolimus

Everolimus is the 40-O- derivative of sirolimus and works similarly to sirolimus as an mTOR inhibitor....

are the three drugs used in coatings which are currently FDA approved in the United States. As opposed to bare metal, drug eluting stents are covered with a medicine that is slowly dispersed with the goal of suppressing the restenosis reaction. The key to the success of drug coating has been (a) choosing effective agents, (b) developing ways of adequately binding the drugs to the stainless surface of the stent

Stent

struts (the coating must stay bound despite marked handling and stent deformation stresses) and (c) developing coating controlled release mechanisms that release the drug slowly over about 30 days. One of the newest innovations in coronary stents is the development of a dissolving stent. Abbott laboratories has used a dissolvable material, polylactic acid, that will completely absorb within 2 years of being implanted.

General

Connolly JE. The development of coronary artery surgery: personal recollections. Tex Heart Inst J 2002;29:10-4. PMID 11995842.
Proudfit WL, Shirey EK, Sones FM Jr. Selective cine coronary arteriography. Correlation with clinical findings in 1,000 patients. Circulation 1966;33:901-10. PMID 5942973.
Sones FM, Shirey EK. Cine coronary arteriography. Mod Concepts Cardiovasc Dis 1962;31:735-8. PMID 13915182.
http://emedicine.medscape.com/article/1603072-overview Coronary CT angiography by Eugene Lin
http://www.businessweek.com/news/2010-09-09/abbott-dissolving-stent-may-be-next-revolution-.html Abbott Dissolving Stent May Be ‘Next Revolution’ by Michelle Fay Cortez

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