Cardiac catheterization (heart cath) is the insertion of a catheter into a chamber or vessel of the heart. This 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 sizes to increase efficiency. Monitors show the fluoroscopy imaging, electrocardiogram (ECG), pressure waves, and more.
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.[citation needed]
Measuring pressures in the heart is also an important aspect of catheterization. The catheters are fluid filled conduits that can transmit pressures to outside the body to pressure transducers. This allows measuring pressure in any part of the heart that a catheter can be maneuvered into.[citation needed]
Measuring blood flow is also possible through several 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.[citation needed]
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
Left heart catheterization (LHC) is an ambiguous term and sometime clarification is required:[citation needed]
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.[citation needed]
Right heart catheterization
Right heart cath using a Swan-Ganz pulmonary artery catheter
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.[citation needed]
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 be done an intensive care unit (ICU) to permit frequent measurement of the hemodynamic parameters in response to interventions.[citation needed]
Parameters obtainable from a right heart catheterization:[citation needed]
Right atrial pressure
Right ventricular pressure
Pulmonary artery pressure
Pulmonary capillary wedge pressure
Systemic vascular resistance
Pulmonary vascular resistance
Cardiac output
Blood oxygenation
Implantation of a CardioMEMS is done during a right heart catheterization. This device is implanted into the pulmonary artery to permit real-time measurement of the pulmonary artery pressure over time.[citation needed]
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.[citation needed]
Indications for cardiac catheterization include the following:[6]
Acute coronary syndromes: ST elevation MI (STEMI), non-ST Elevation MI (NSTEMI), and unstable angina
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
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
Posteroanterior and lateral chest radiographs of a pacemaker with normally located leads in the right atrium (white arrow) and right ventricle (black arrowhead), respectively.
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 subclavian vein and electrodes are placed in the right atrium, right ventricle, and coronary sinus (for the left ventricle stimulation).[citation needed]
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.[citation needed]
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.[citation needed]
Shunt evaluation
Atrial septal defect with left-to-right shunt
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 Qp:Qs ratio. Elevation of the Qp:Qs ratio above 1.5 to 2.0 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.[citation needed]
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.[citation needed]
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.[citation needed]
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.[citation needed]
Complications
Complications of cardiac catheterization and tools used during catheterization include, but not limited to:[citation needed]
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.[citation needed]
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).[citation needed]
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.[citation needed]
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).[citation needed]
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.
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.[citation needed]
Related Research Articles
Cardiology is the study of the heart. Cardiology is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease, and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists, a specialty of internal medicine. Pediatric cardiologists are pediatricians who specialize in cardiology. Physicians who specialize in cardiac surgery are called cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery.
A coronary catheterization is a minimally invasive procedure to access the coronary circulation and blood filled chambers of the heart using a catheter. It is performed for both diagnostic and interventional (treatment) purposes.
dextro-Transposition of the great arteries is a potentially life-threatening birth defect in the large arteries of the heart. The primary arteries are transposed.
Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this does not naturally close after birth it is referred to as a patent (open) foramen ovale (PFO). It is common in patients with a congenital atrial septal aneurysm (ASA).
Interventional cardiology is a branch of cardiology that deals specifically with the catheter based treatment of structural heart diseases. Andreas Gruentzig is considered the father of interventional cardiology after the development of angioplasty by interventional radiologist Charles Dotter.
The Fontan procedure or Fontan–Kreutzer procedure is a palliative surgical procedure used in children with univentricular hearts. It involves diverting the venous blood from the inferior vena cava (IVC) and superior vena cava (SVC) to the pulmonary arteries. The procedure varies for differing congenital heart pathologies. For example in tricuspid atresia, the procedure can be done where the blood does not pass through the morphologic right ventricle; i.e., the systemic and pulmonary circulations are placed in series with the functional single ventricle. Whereas in hypoplastic left heart syndrome, the heart is more reliant on the more functional right ventricle to provide blood flow to the systemic circulation. The procedure was initially performed in 1968 by Francis Fontan and Eugene Baudet from Bordeaux, France, published in 1971, simultaneously described in 1971 by Guillermo Kreutzer from Buenos Aires, Argentina, and finally published in 1973.
A pulmonary artery catheter (PAC), also known as a Swan-Ganz catheter or right heart catheter, is a balloon-tipped catheter that is inserted into a pulmonary artery in a procedure known as pulmonary artery catheterization or right heart catheterization. Pulmonary artery catheterization is a useful measure of the overall function of the heart particularly in those with complications from heart failure, heart attack, arrythmias or pulmonary embolism. It is also a good measure for those needing intravenous fluid therapy, for instance post heart surgery, shock, and severe burns. The procedure can also be used to measure pressures in the heart chambers.
Transposition of the great vessels (TGV) is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels: superior and/or inferior venae cavae, pulmonary artery, pulmonary veins, and aorta. Congenital heart diseases involving only the primary arteries belong to a sub-group called transposition of the great arteries (TGA), which is considered the most common congenital heart lesion that presents in neonates.
Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located on the right side of the heart between the right ventricle and pulmonary artery. In a normal functioning heart, the opening to the pulmonary valve has three flaps that open and close.
Levo-Transposition of the great arteries is an acyanotic congenital heart defect in which the primary arteries are transposed, with the aorta anterior and to the left of the pulmonary artery; the morphological left and right ventricles with their corresponding atrioventricular valves are also transposed.
An embolus, is described as a free-floating mass, located inside blood vessels that can travel from one site in the blood stream to another. An embolus can be made up of solid, liquid, or gas. Once these masses get "stuck" in a different blood vessel, it is then known as an "embolism." An embolism can cause ischemia—damage to an organ from lack of oxygen. A paradoxical embolism is a specific type of embolism in which the embolus travels from the right side of the heart to the left side of the heart and lodges itself in a blood vessel known as an artery. Thus, it is termed "paradoxical" because the embolus lands in an artery, rather than a vein.
A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles.
Arterial switch operation (ASO) or arterial switch, is an open heart surgical procedure used to correct dextro-transposition of the great arteries (d-TGA).
A cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. The direction may be controlled by left and/or right heart pressure, a biological or artificial heart valve or both. The presence of a shunt may also affect left and/or right heart pressure either beneficially or detrimentally.
Lutembacher's syndrome is a very rare form of congenital heart disease that affects one of the chambers of the heart as well as a valve. It is commonly known as both congenital atrial septal defect (ASD) and acquired mitral stenosis (MS). Congenital atrial septal defect refers to a hole being in the septum or wall that separates the two atria; this condition is usually seen in fetuses and infants. Mitral stenosis refers to mitral valve leaflets sticking to each other making the opening for blood to pass from the atrium to the ventricles very small. With the valve being so small, blood has difficulty passing from the left atrium into the left ventricle. Septal defects that may occur with Lutembacher's syndrome include: Ostium primum atrial septal defect or ostium secundum which is more prevalent.
Atrial septostomy is a surgical procedure in which a small hole is created between the upper two chambers of the heart, the atria. This procedure is primarily used to palliate dextro-Transposition of the great arteries or d-TGA, a life-threatening cyanotic congenital heart defect seen in infants. It is performed prior to an arterial switch operation. Atrial septostomy has also seen limited use as a surgical treatment for pulmonary hypertension. The first atrial septostomy was developed by Vivien Thomas in a canine model and performed in humans by Alfred Blalock. The Rashkind balloon procedure, a common atrial septostomy technique, was developed in 1966 by American cardiologist William Rashkind at the Children's Hospital of Philadelphia.
The following outline is provided as an overview of and topical guide to cardiology, the branch of medicine dealing with disorders of the human heart. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians who specialize in cardiology are called cardiologists.
A hybrid cardiac surgical procedure in a narrow sense is defined as a procedure that combines a conventional, more invasive surgical part with an interventional part, using some sort of catheter-based procedure guided by fluoroscopy imaging in a hybrid operating room (OR) without interruption. The hybrid technique has a reduced risk of surgical complications and has shown decreased recovery time. It can be used to treat numerous heart diseases and conditions and with the increasing complexity of each case, the hybrid surgical technique is becoming more common.
The Senning procedure is an atrial switch heart operation performed to treat transposition of the great arteries. It is named after its inventor, the Swedish cardiac surgeon Åke Senning (1915–2000), also known for implanting the first permanent cardiac pacemaker in 1958.
Percutaneous pulmonary valve implantation (PPVI), also known as transcatheter pulmonary valve replacement (TPVR), is the replacement of the pulmonary valve via catheterization through a vein. It is a significantly less invasive procedure in comparison to open heart surgery and is commonly used to treat conditions such as pulmonary atresia.
References
↑ 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. ISSN1873-1570. PMID25195073.
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