Cardiac catheterization

Cardiac catheterization (heart cath) is the insertion

of a catheter into a chamber or vessel of the heart. This Cardiac catheterization
is done both for diagnostic and interventional
purposes.

A common example of cardiac catheterization is

coronary catheterization that involves catheterization
of the coronary arteries for coronary artery disease and
myocardial infarctions ("heart attacks").
Catheterization is most often performed in special
laboratories with fluoroscopy and highly maneuverable
tables. These "cath labs" are often equipped with
cabinets of catheters, stents, balloons, etc. of various Cardiac catheterization lab
sizes to increase efficiency. Monitors show the Other names Cath, heart cath
fluoroscopy imaging, electrocardiogram (ECG),
Specialty Cardiology
pressure waves, and more.

Uses
Coronary angiography is a diagnostic procedure that
allows visualization of the coronary vessels.
Fluoroscopy is used to visualize the lumens of the
arteries as a 2-D projection. Should these arteries
show narrowing or blockage, then techniques exist to
open these arteries. Percutaneous coronary
intervention is a blanket term that involves the use of
mechanical stents, balloons, etc. to increase blood
flow to previously blocked (or occluded) vessels.

Measuring pressures in the heart is also an important A person undergoing a procedure where an 8 F
aspect of catheterization. The catheters are fluid filled introducer was placed in the right jugular vein
conduits that can transmit pressures to outside the using a 5F MAK access kit. A 7 F balloon tipped
body to pressure transducers. This allows measuring catheter was introduced via the venous sheath,
the balloon was inflated and the catheter was
pressure in any part of the heart that a catheter can be
advanced through the right heart chambers into
maneuvered into.
the pulmonary capillary wedge position. Right
sided pressures were obtained and cardiac output
Measuring blood flow is also possible through several
was measured using thermodilution.
methods. Most commonly, flows are estimated using
the Fick principle and thermodilution. These methods
have drawbacks, but give invasive estimations of the cardiac output, which can be used to make clinical
decisions (e.g., cardiogenic shock, heart failure) to improve the person's condition.
Cardiac catheterization can be used as part of a therapeutic regimen to improve outcomes for survivors of
out-of-hospital cardiac arrest.[1]

Cardiac catheterization often requires the use of fluoroscopy to visualize the path of the catheter as it
enters the heart or as it enters the coronary arteries. The coronary arteries are known as "epicardial
vessels" as they are located in the epicardium, the outermost layer of the heart.[2] The use of fluoroscopy
requires radiopaque contrast, which in rare cases can lead to contrast-induced kidney injury (see Contrast-
induced nephropathy). People are constantly exposed to low doses of ionizing radiation during
procedures.[3] Ideal table positioning between the x-ray source and receiver, and radiation monitoring via
thermoluminescent dosimetry, are two main ways of reducing a person's exposure to radiation.[3] People
with certain comorbidities (people who have more than one condition at the same time) have a higher risk
of adverse events during the cardiac catheterization procedure.[3] These comorbidity conditions include
aortic aneurysm, aortic stenosis, extensive three-vessel coronary artery disease, diabetes, uncontrolled
hypertension, obesity, chronic kidney disease, and unstable angina.[4]

Left heart catheterization (LHC)

Left heart catheterization (LHC) is an ambiguous term and
sometime clarification is required:

LHC can mean measuring the pressures of the left

side of the heart.
LHC can be synonymous with coronary
angiography.
technique is also used to assess the amount of occlusion (or
blockage) in a coronary artery, often described as a
percentage of occlusion. A thin, flexible wire is inserted into
either the femoral artery or the radial artery and threaded
toward the heart until it is in the ascending aorta. Radial
access is not associated with an increased risk of stroke over
femoral access.[5] At this point, a catheter is guided over the
wire into the ascending aorta, where it can be maneuvered
into the coronary arteries through the coronary ostia.[4] In this
position, the interventional cardiologist can inject contrast
and visualize the flow through the vessel. If necessary, the
physician can utilize percutaneous coronary intervention techniques, including the use of a stent (either
bare-metal or drug-eluting) to open the blocked vessel and restore appropriate blood flow. In general,
occlusions greater than 70% of the width of the vessel lumen are thought to require intervention.
However, in cases where multiple vessels are blocked (so-called "three-vessel disease"), the
interventional cardiologist may opt instead to refer the patient to a cardiothoracic surgeon for coronary
artery bypass graft (CABG; see Coronary artery bypass surgery) surgery.

Right heart catheterization (RHC)

Right heart catheterization (RHC) allows the physician to determine the pressures within the heart
(intracardiac pressures). The heart is most often accessed via the internal jugular or femoral vein; arteries
are not used. Values are commonly obtained for the right atrium, right ventricle, pulmonary artery, and
pulmonary capillary "wedge" pressures. Right heart
catheterizations also allow the physician to estimate
the cardiac output, the amount of blood that flows
from the heart each minute, and the cardiac index, a
hemodynamic parameter that relates the cardiac
output to a patient's body size. Determination of
cardiac output can be done by releasing a small
amount of saline solution (either chilled or at room
temperature) in one area of the heart and measuring
the change in blood temperature over time in another
area of the heart.

Right heart catheterization is often done for

pulmonary hypertension, heart failure, and
cardiogenic shock. The pulmonary artery catheter can
be placed, used, and removed, or it can be placed and
left in place for continuous monitoring. The latter can Right heart cath using a Swan-Ganz pulmonary
be done an intensive care unit (ICU) to permit artery catheter
frequent measurement of the hemodynamic
parameters in response to interventions.

Parameters obtainable from a right heart catheterization:

Right atrial pressure

Right ventricular pressure
Pulmonary artery pressure
Pulmonary capillary wedge pressure
Systemic vascular resistance
Pulmonary vascular resistance
Cardiac output
Blood oxygenation

Coronary catheterization
Coronary catheterization is an invasive process and comes with risks that include stroke, heart attack, and
death. Like any procedure, the benefits should outweigh the risks and so this procedure is reserved for
those with symptoms of serious heart diseases and is never used for screening purposes. Other, non-
invasive tests are better used when the diagnosis or certainty of the diagnosis is not as clear.

Indications for cardiac catheterization include the following:[6]

Acute coronary syndromes: ST elevation MI (STEMI), non-ST Elevation MI (NSTEMI), and

unstable angina
Evaluation of coronary artery disease as indicated by
Abnormal stress test
As part of the pre-op evaluation for other cardiac procedures (e.g., valve replacement)
as coronary artery bypass grafting may be done at the same time
 Risk stratification for high cardiac risk surgeries (e.g., endovascular aneurysm repair)
Persistent chest pain despite medical therapy thought to be cardiac in origin
New-onset unexplained heart failure
Survival of sudden cardiac death or dangerous cardiac arrhythmias
Workup of suspected Prinzmetal angina (coronary vasospasm)
Right heart catheterization, along with pulmonary function testing and other testing should be done to
confirm pulmonary hypertension prior to having vasoactive pharmacologic treatments approved and
initiated.[7]

to measure intracardiac and intravascular blood pressures

to take tissue samples for biopsy
to inject various agents for measuring blood flow in the heart; also to detect and quantify the
presence of an intracardiac shunt
to inject contrast agents in order to study the shape of the heart vessels and chambers and
how they change as the heart beats

Pacemakers and defibrillators

Placement of internal pacemakers and
defibrillators are done through catheterization
as well. An exception to this is placement of
electrodes on the outer surface of the heart
(called epicardial electrodes). Otherwise,
electrodes are placed through the venous
system into the heart and left there
permanently. Typically, these devices are
placed in the left upper chest and enter the left
Posteroanterior and lateral chest radiographs of a
subclavian vein and electrodes are placed in
pacemaker with normally located leads in the right atrium
the right atrium, right ventricle, and coronary (white arrow) and right ventricle (black arrowhead),
sinus (for the left ventricle stimulation). respectively.

Valve assessment
Echocardiography is a non-invasive method to evaluate the heart valves. However, sometimes the valve
pressure gradients need to be measured directly because echo is equivocal for the severity of valve
disease. Invasive assessment of the valve can be done with catheterization by placing a catheter across the
valve and measuring the pressures simultaneously on each side of the valve to obtain the pressure
gradient.[8] In conjunction with a right heart catheterization, the valve area can be estimated. For
example, in aortic valve area calculation the Gorlin equation can be used to calculate the area if the
cardiac output, pressure gradient, systolic period, and heart rate are known.

Pulmonary angiography
Evaluation of the blood flow to the lungs can be done invasively through catheterization. Contrast is
injected into the pulmonary trunk, left or right pulmonary artery, or segment of the pulmonary artery.

Shunt evaluation
Cardiac shunts can be evaluated through catheterization. Using
oxygen as a marker, the oxygen saturation of blood can be
sampled at various locations in and around the heart. For example,
a left-to-right atrial septal defect will show a marked increase in
oxygen saturation in the right atrium, ventricle, and pulmonary
artery as compared to the mixed venous oxygen saturation from
the oxygenated blood from the lungs mixing into the venous return
to the heart. Utilizing the Fick principle, the ratio of blood flow in
the lungs (Qp) and system circulations (Qs) can calculate the Atrial septal defect with left-to-right
Qp:Qs ratio. Elevation of the Qp:Qs ratio above 1.5 to 2.0 shunt
suggests that there is a hemodynamically significant left-to-right
shunt (such that the blood flow through the lungs is 1.5 to 2.0
times more than the systemic circulation). This ratio can be evaluated non-invasively with
echocardiography too, however.

A "shunt run" is often done when evaluating for a shunt by taking blood samples from superior vena cava
(SVC), inferior vena cava (IVC), right atrium, right ventricle, pulmonary artery, and system arterial.
Abrupt increases in oxygen saturation support a left-to-right shunt and lower than normal systemic
arterial oxygen saturation supports a right-to-left shunt. Samples from the SVC & IVC are used to
calculate mixed venous oxygen saturation.

Ventriculography
By injecting contrast into the left ventricle, the outline of the
ventricle can be measured in both systole and diastole to estimate
the ejection fraction (a marker of heart function). Due to the high
contrast volumes and injection pressures, this is often not
performed unless other, non-invasive methods are not acceptable,
not possible, or conflicting.

Percutaneous or transcutaneous aortic valve

replacement (TAVR)
Advancements in cardiac catheterization have permitted
replacement of heart valves by means of blood vessels. This
method allows valve replacement without open heart surgery and can be performed on people who are
high-risk for such a surgery.

Balloon septostomy
Catheterization can also be used to perform balloon septostomy, which is the widening of a foramen
ovale, patent foramen ovale (PFO), or atrial septal defect (ASD) using a balloon catheter. This can be
done in certain congenital heart diseases in which the mechanical shunting is required to sustain life such
as in transposition of the great vessels.

Alcohol septal ablation (ASA)

Hypertrophic cardiomyopathy is a disease in which the myocardium is thickened and can cause blood
flow obstruction. If hemodynamically significant, this excess muscle can be removed to improve blood
flow. Surgically, this can be done with septal myectomy. However, it can be done through catheterization
and by injecting ethanol to destroy the tissue in an alcohol septal ablation. This is done by selected an
appropriate septal artery supplying the intended area and, essentially, causing a localized, controlled
myocardial infarction of the area with ethanol.

Complications
Complications of cardiac catheterization and tools used during catheterization include, but not limited to:

Death
Stroke
Heart attack
Ventricular ectopy and ventricular arrhythmias
Pericardial effusion
Bleeding: internal and external
Infection
Radiation burn
Contrast-induced nephropathy from contrast use
The likelihood of these risks depends on many factors that include the procedure being performed, the
overall health state of the patient, situational (elective vs emergent), medications (e.g., anticoagulation),
and more.

Procedure
"Cardiac catheterization" is a general term for a group of procedures. Access to the heart is obtained
through a peripheral artery or vein. Commonly, this includes the radial artery, internal jugular vein, and
femoral artery/vein. Each blood vessel has its advantages and disadvantages. Once access is obtained,
plastic catheters (tiny hollow tubes) and flexible wires are used to navigate to and around the heart.
Catheters come in numerous shapes, lengths, diameters, number of lumens, and other special features
such as electrodes and balloons. Once in place, they are used to measure or intervene. Imaging is an
important aspect to catheterization and commonly includes fluoroscopy but can also include forms of
echocardiography (TTE, TEE, ICE) and ultrasound (IVUS).

Obtaining access uses the Seldinger technique by puncturing the vessel with a needle, placing a wire
through the needle into the lumen of the vessel, and then exchanging the needle for a larger plastic sheath.
Finding the vessel with a needle can be challenging and both ultrasound and fluoroscopy can be used to
aid in finding and confirming access. Sheaths typically have a side port that can be used to withdraw
blood or injection fluids/medications, and they also have an end hole that permits introducing the
catheters, wires, etc. coaxially into the blood vessel.

Once access is obtained, what is introduced into the vessel depends on the procedure being performed.
Some catheters are formed to a particular shape and can really only be manipulated by
inserting/withdrawing the catheter in the sheath and rotating the catheter. Others may include internal
structures that permit internal manipulation (e.g., intracardiac echocardiography).

Finally, when the procedure is completed, the catheters are removed and the sheath is removed. With
time, the hole made in the blood vessel will heal. Vascular closure devices can be used to speed along
hemostasis.

Equipment
Much equipment is required for a facility to perform the numerous possible procedures for cardiac
catheterization.

General:

Catheters
Film or Digital Camera
Electrocardiography monitors
External defibrillator
Fluoroscopy
Pressure transducers
Sheaths
Percutaneous coronary intervention:

Coronary stents: bare-metal stent (BMS) and drug-eluting stent (DES)

Angioplasty balloons
Atherectomy lasers and rotational devices
Left atrial appendage occlusion devices
Electrophysiology:

Ablation catheters: radiofrequency (RF) and cryo

Pacemakers
Defibrillators

History
The history of cardiac catheterization dates back to Stephen Hales (1677-1761) and Claude Bernard
(1813-1878), who both used it on animal models. Clinical application of cardiac catheterization begins
with Dr. Werner Forssmann in 1929, who inserted a catheter into the vein of his own forearm, guided it
fluoroscopically into his right atrium, and took an X-ray picture of it.[9] However, even after this
achievement, hospital administrators removed Forssmann from his position owing to his unorthodox
methods.[9] During World War II, André Frédéric Cournand, a physician at NewYork-
Presbyterian/Columbia, then Columbia-Bellevue, opened the first catheterization lab. In 1956, Forssmann
and Cournand were co-recipients of the Nobel Prize in Physiology or Medicine for the development of
cardiac catheterization. Dr. Eugene A. Stead performed research in the 1940s, which paved the way for
cardiac catheterization in the USA.

References
1. Camuglia, Anthony C.; Randhawa, Varinder K.; Lavi, Shahar; Walters, Darren L. (November
2014). "Cardiac catheterization is associated with superior outcomes for survivors of out of
hospital cardiac arrest: review and meta-analysis". Resuscitation. 85 (11): 1533–1540.
doi:10.1016/j.resuscitation.2014.08.025 (https://doi.org/10.1016%2Fj.resuscitation.2014.08.
025). ISSN 1873-1570 (https://search.worldcat.org/issn/1873-1570). PMID 25195073 (http
s://pubmed.ncbi.nlm.nih.gov/25195073).
2. Malouf JF, Edwards WD, Tajik A, Seward JB. Chapter 4. Functional Anatomy of the Heart.
In: Fuster V, Walsh RA, Harrington RA. eds. Hurst's The Heart, 13e. New York, NY:
McGraw-Hill; 2011. http://accessmedicine.mhmedical.com/content.aspx?
bookid=376&Sectionid=40279729 Archived (https://web.archive.org/web/20150519072349/h
ttp://accessmedicine.mhmedical.com/content.aspx?bookid=376&Sectionid=40279729)
2015-05-19 at the Wayback Machine. Accessed May 09, 2015.
3. Christopoulos, Georgios; Makke, Lorenza; Christakopoulos, Georgios; Kotsia, Anna;
Rangan, Bavana V.; Roesle, Michele; Haagen, Donald; Kumbhani, Dharam J.; Chambers,
Charles E. (2016-02-01). "Optimizing Radiation Safety in the Cardiac Catheterization
Laboratory: A Practical Approach". Catheterization and Cardiovascular Interventions. 87 (2):
291–301. doi:10.1002/ccd.25959 (https://doi.org/10.1002%2Fccd.25959). ISSN 1522-726X
(https://search.worldcat.org/issn/1522-726X). PMID 26526181 (https://pubmed.ncbi.nlm.nih.
gov/26526181). S2CID 12502220 (https://api.semanticscholar.org/CorpusID:12502220).
4. Kern, Morton J.; Sorajja, Paul; Lim, Michael J. (2015-06-01). The cardiac catheterization
handbook. Kern, Morton J.,, Sorajja, Paul,, Lim, Michael J. (Sixth ed.). Philadelphia, PA.
ISBN 9780323341554. OCLC 910964299 (https://search.worldcat.org/oclc/910964299).
5. Sirker, Alex; Kwok, Chun Shing; Kotronias, Rafail; Bagur, Rodrigo; Bertrand, Olivier; Butler,
Robert; Berry, Colin; Nolan, James; Oldroyd, Keith (November 2016). "Influence of access
site choice for cardiac catheterization on risk of adverse neurological events: A systematic
review and meta-analysis" (http://eprints.keele.ac.uk/1987/1/Manuscript%20Am%20Heart%
20J%2015June2016.doc). American Heart Journal. 181: 107–119.
doi:10.1016/j.ahj.2016.06.027 (https://doi.org/10.1016%2Fj.ahj.2016.06.027). ISSN 1097-
6744 (https://search.worldcat.org/issn/1097-6744). PMID 27823682 (https://pubmed.ncbi.nl
m.nih.gov/27823682).
6. Sabatine, Marc S., ed. (2011). Pocket medicine (4th ed.). Philadelphia: Wolters Kluwer
Health/Lippincott Williams & Wilkins. ISBN 978-1608319053.
7. American College of Chest Physicians; American Thoracic Society (September 2013), "Five
Things Physicians and Patients Should Question" (http://www.choosingwisely.org/doctor-pati
ent-lists/american-college-of-chest-physicians-and-american-thoracic-society/), Choosing
Wisely: an initiative of the ABIM Foundation, American College of Chest Physicians and
American Thoracic Society, retrieved 6 January 2013
8. Grossman & Baim's cardiac catheterization, angiography, and intervention. Moscucci,
Mauro, (Eighth edition). Philadelphia. p. 272. ISBN 9781451127409. OCLC 829739969.
9. West, JB (1 October 2017). "The beginnings of cardiac catheterization and the resulting
impact on pulmonary medicine" (https://doi.org/10.1152%2Fajplung.00133.2017). American
Journal of Physiology. Lung Cellular and Molecular Physiology. 313 (4): L651 – L658.
 doi:10.1152/ajplung.00133.2017 (https://doi.org/10.1152%2Fajplung.00133.2017).
PMID 28839102 (https://pubmed.ncbi.nlm.nih.gov/28839102).

External links
MedlinePlus Medical Encyclopedia: Cardiac catheterization (https://www.nlm.nih.gov/medlin
eplus/ency/article/003419.htm)
eMedicine: Cardiac Catheterization (Left Heart) (http://www.emedicine.com/med/topic2958.h
tm)

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