Cardiac Catheterization

Left heart catheterization is most commonly used to assess

Left heart catheterization is also used to assess

The procedure is done via femoral, subclavian, radial, or brachial artery puncture, with a catheter passed into the coronary artery ostia and/or across the aortic valve into the left ventricle (LV).

Catheterization of the left atrium (LA) and LV is occasionally done using transseptal perforation during right heart catheterization.

Right heart catheterization is commonly used to measure

The most frequent indications for right heart catheterization are to assess hemodynamics, diagnose pulmonary hypertension, guide therapy, and assess need for cardiac transplantation or mechanical cardiac support (eg, a ventricular assist device).

PAOP approximates left atrial and left ventricular end-diastolic pressure. In seriously ill patients, PAOP helps assess volume status and, with simultaneous measurements of cardiac output, can help guide therapy.

Right heart catheterization is also useful for assessing cardiac filling pressures, pulmonary vascular resistance, tricuspid or pulmonic valve function, intracardiac shunts, and right ventricular pressure.

Right heart pressure measurements may help in the diagnosis of cardiomyopathy Overview of Cardiomyopathies A cardiomyopathy is a primary disorder of the heart muscle. It is distinct from structural cardiac disorders such as coronary artery disease, valvular disorders, and congenital heart disorders... read more , constrictive pericarditis Constrictive pericarditis Pericarditis is inflammation of the pericardium, often with fluid accumulation in the pericardial space. Pericarditis may be caused by many disorders (eg, infection, myocardial infarction, trauma... read more , and cardiac tamponade Cardiac Tamponade Cardiac tamponade is accumulation of blood in the pericardial sac of sufficient volume and pressure to impair cardiac filling. Patients typically have hypotension, muffled heart tones, and distended... read more . when noninvasive testing is nondiagnostic, and it is an essential part of the assessment for cardiac transplantation or mechanical cardiac support (eg, use of a ventricular assist device).

The procedure Procedure Some monitoring of critical care patients depends on direct observation and physical examination and is intermittent, with the frequency depending on the patient’s illness. Other monitoring... read more is done via femoral, subclavian, internal jugular, or antecubital vein puncture. A catheter is passed into the right atrium, through the tricuspid valve, into the right ventricle, and across the pulmonary valve into the pulmonary artery.

Selective catheterization of the coronary sinus can also be done.

Hemodynamic assessment via right heart catheterization during exercise is increasingly being done as part of the workup for dyspnea of uncertain etiology. The test can be done at the same time as cardiopulmonary exercise testing, called invasive cardiopulmonary exercise testing. This is considered the standard for diagnosis of cardiac limitation to exercise but is currently available at relatively few centers. An exercise right heart catheterization should be considered in patients at intermediate pretest probability for heart failure with preserved ejection fraction Classification Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more if the diagnosis is uncertain after an initial evaluation. An increase in the PAOP > 25 mm Hg confirms the diagnosis when patients have signs and symptoms of heart failure and a normal ejection fraction.

Injection of radiopaque contrast agent into coronary or pulmonary arteries, the aorta, and cardiac chambers is useful in certain circumstances. Digital subtraction angiography is used for nonmoving arteries and for chamber cineangiography.

Coronary angiography via left heart catheterization is used to evaluate coronary artery anatomy in various clinical situations, as in patients with suspected coronary atherosclerotic or congenital disease, valvular disorders Overview of Cardiac Valvular Disorders Any heart valve can become stenotic or insufficient (also termed regurgitant or incompetent), causing hemodynamic changes long before symptoms. Most often, valvular stenosis or insufficiency... read more before valvular replacement, or unexplained heart failure Heart Failure (HF) Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more .

Pulmonary angiography via right heart catheterization can be used to diagnose pulmonary embolism Diagnosis Pulmonary embolism (PE) is the occlusion of pulmonary arteries by thrombi that originate elsewhere, typically in the large veins of the legs or pelvis. Risk factors for pulmonary embolism are... read more . Intraluminal filling defects or arterial cutoffs are diagnostic. Radiopaque contrast agent is usually selectively injected into one or both pulmonary arteries and their segments. Computed tomographic pulmonary angiography (CTPA) has largely replaced right heart catheterization for diagnosis of acute pulmonary embolism. Pulmonary angiography via right heart catheterization remains commonly used to determine a management plan for suspected chronic thromboembolic disease.

Aortic angiography via left heart catheterization is used to assess aortic regurgitation Aortic Regurgitation Aortic regurgitation (AR) is incompetency of the aortic valve causing backflow from the aorta into the left ventricle during diastole. Causes include valvular degeneration and aortic root dilation... read more , coarctation Coarctation of the Aorta Coarctation of the aorta is a localized narrowing of the aortic lumen that results in upper-extremity hypertension, left ventricular hypertrophy, and malperfusion of the abdominal organs and... read more , patent ductus arteriosus Patent Ductus Arteriosus (PDA) Patent ductus arteriosus (PDA) is a persistence of the fetal connection (ductus arteriosus) between the aorta and pulmonary artery after birth. In the absence of other structural heart abnormalities... read more , and dissection Aortic Dissection Aortic dissection is the surging of blood through a tear in the aortic intima with separation of the intima and media and creation of a false lumen (channel). The intimal tear may be a primary... read more .

Ventriculography is used to visualize ventricular wall motion and ventricular outflow tracts, including subvalvular, valvular, and supravalvular regions. It is also used to estimate severity of mitral valve regurgitation Mitral Regurgitation Mitral regurgitation (MR) is incompetency of the mitral valve causing flow from the left ventricle (LV) into the left atrium during ventricular systole. MR can be primary (common causes are... read more and determine its pathophysiology. After left ventricular mass and volume are determined from single planar or biplanar ventricular angiograms, end-systolic and end-diastolic volumes and ejection fraction can be calculated.

Coronary angiography shows the presence and degree of stenosis but not the functional significance of the lesion (ie, how much blood flows across the stenosis) or whether a specific lesion is likely to be the cause of symptoms.

Extremely thin guidewires with pressure sensors or Doppler flow sensors are available. Data from these sensors can be used to estimate coronary artery blood flow, which is expressed as fractional flow reserve (FFR). FFR is the ratio of maximal flow through the stenotic area to normal maximal flow obtained during hyperemia (most commonly with adenosine); an FFR of < 0.75 to 0.8 is considered abnormal. Newer techniques of measuring coronary blood flow, including instantaneous wave-free ratio (iFR) and diastolic hyperemia-free ratio (DFR), have been developed. These techniques have the advantage of not requiring hyperemia. Both iFR and DFR measure gradients across a stenosis during a period in diastole; an iFR or DFR of ≤ 0.89 is considered abnormal (1, 2 Tests during cardiac catheterization reference Cardiac catheterization is the passage of a catheter through peripheral arteries or veins into cardiac chambers, the pulmonary artery, and coronary arteries and veins. Cardiac catheterization... read more ).

These flow estimates correlate well with the need for intervention and long-term outcome; patients with lesions with FFR > 0.8, iFR > 0.89, or DFR > 0.89 do not seem to benefit from placement of a stent. These flow measurements are most useful with intermediate lesions (40 to 70% stenosis) and with multiple lesions (to identify those that are clinically most significant).

Miniature ultrasound transducers on the end of coronary artery catheters can produce images of coronary vessel lumina and walls and delineate blood flow. Intravascular ultrasonography is being increasingly used at the same time as coronary angiography.

Optical coherence tomography is an optical analog of intracoronary ultrasound imaging that measures the amplitude of backscattered light to determine the temperature of coronary plaques and can help determine whether lesions are at high risk of future rupture (leading to acute coronary syndromes Overview of Acute Coronary Syndromes (ACS) Acute coronary syndromes result from acute obstruction of a coronary artery. Consequences depend on degree and location of obstruction and range from unstable angina to non–ST-segment elevation... read more ). The indications and appropriate use for OCT are currently uncertain.

Measuring blood oxygen content at successive levels in the heart and great vessels can help determine the presence, direction, and volume of central shunts. The maximal normal difference in oxygen content between structures is as follows:

If the blood oxygen content in a chamber exceeds that of the more proximal chamber by more than these values, a left-to-right shunt at that level is probable. Right-to-left shunts are strongly suspected when LA, LV, or arterial oxygen saturation is low (≤ 92%) and does not improve when pure oxygen (fractional inspirational O2 = 1.0) is given. Left heart or arterial desaturation plus increased oxygen content in blood samples drawn beyond the shunt site on the right side of circulation suggests a bidirectional shunt.

Cardiac output (CO) is the volume of blood ejected by the heart per minute (normal at rest: 4 to 8 L/minute). Techniques (see table Cardiac Output Equations Cardiac Output Equations ) used to calculate CO include

With the Fick technique, CO is proportional to oxygen consumption divided by arteriovenous oxygen difference.

Dilution techniques rely on the assumption that after an indicator is injected into the circulation, it appears and disappears proportionately to CO.

Usually, CO is expressed in relation to body surface area (BSA) as the cardiac index (CI) in L/minute/m² (ie, CI = CO/BSA—see table Normal Values for Cardiac Index and Related Measures Normal Values for Cardiac Index and Related Measurements ). BSA is calculated using DuBois height (ht)–weight (wt) equation:

Endomyocardial biopsy helps assess transplant rejection and myocardial disorders due to infection or infiltrative diseases. The biopsy catheter (bioptome) can be passed into either ventricle, usually the right. Three to 5 samples of myocardial tissue are removed from the septal endocardium. The main complication of endomyocardial biopsy, cardiac perforation, occurs in 0.3 to 0.5% of patients; it may cause hemopericardium leading to cardiac tamponade Cardiac Tamponade Cardiac tamponade is accumulation of blood in the pericardial sac of sufficient volume and pressure to impair cardiac filling. Patients typically have hypotension, muffled heart tones, and distended... read more . Injury to the tricuspid valve and supporting chordae may also occur and can lead to tricuspid regurgitation Tricuspid Regurgitation Tricuspid regurgitation (TR) is insufficiency of the tricuspid valve causing blood flow from the right ventricle to the right atrium during systole. The most common cause is dilation of the... read more .

Injection of radiopaque contrast agent produces a transient sense of warmth throughout the body in many patients. Tachycardia, a slight fall in systemic pressure, an increase in cardiac output, nausea, vomiting, and coughing may occur. Rarely, bradycardia occurs when a large amount of a contrast agent is injected; asking the patient to cough often restores normal rhythm.

More serious reactions (see also Radiographic Contrast Agents and Contrast Reactions Radiographic Contrast Agents and Contrast Reactions Radiopaque contrast agents are often used in radiography and fluoroscopy to help delineate borders between tissues with similar radiodensity. Most contrast agents are iodine based. Iodinated... read more ) include

Allergic reactions to radiographic contrast may include urticaria and conjunctivitis, which usually respond to diphenhydramine 50 mg IV. Anaphylaxis Anaphylaxis Anaphylaxis is an acute, potentially life-threatening, IgE-mediated allergic reaction that occurs in previously sensitized people when they are reexposed to the sensitizing antigen. Symptoms... read more , with bronchospasm, laryngeal edema, and dyspnea are rare reactions with an approximate frequency of about 1/5000 tests (1 Complications reference Cardiac catheterization is the passage of a catheter through peripheral arteries or veins into cardiac chambers, the pulmonary artery, and coronary arteries and veins. Cardiac catheterization... read more ); they are treated with inhaled albuterol or subcutaneous 1:1000 epinephrine 0.3 to 0.4 mL. Treatment of anaphylaxis Treatment Anaphylaxis is an acute, potentially life-threatening, IgE-mediated allergic reaction that occurs in previously sensitized people when they are reexposed to the sensitizing antigen. Symptoms... read more is with epinephrine and other supportive measures. Patients with a history of allergic reaction to contrast may be premedicated with prednisone (50 mg orally 13 hours, 7 hours, and 1 hour before injection of contrast) and diphenhydramine (50 mg orally or IM 1 hour before the injection). If patients require imaging immediately, they can be given diphenhydramine 50 mg orally or IM 1 hour before injection of contrast and hydrocortisone 200 mg IV every 4 hours until imaging is completed.

Contrast-induced kidney injury Contrast Nephropathy Contrast nephropathy is worsening of renal function after IV administration of radiocontrast and is usually temporary. Diagnosis is based on a progressive rise in serum creatinine 24 to 48 hours... read more is defined as impairment of renal function (either a 25% increase in serum creatinine from baseline or a 0.5 mg/dL [44 micromole/L] increase in absolute value) within 48 to 72 hours of IV contrast administration. For patients at risk, use of lowest possible dose of low-osmolar or iso-osmolar contrast, avoidance of multiple contrast studies within a short period of time, and infusion of a total 10 to 15 mL/kg normal saline IV beginning 4 to 6 hours before angiography and 6 to 12 hours afterward reduces this risk substantially. In patients at risk of impaired renal function, assess serum creatinine 48 hours after injection of contrast.

If the catheter tip contacts the ventricular endocardium, ventricular arrhythmias commonly occur, but ventricular fibrillation is rare. If it occurs, direct current cardioversion Defibrillation Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more (DC cardioversion) is administered immediately.

Disruption of an atherosclerotic plaque by the catheter can release a shower of atheroemboli. Emboli from the aorta may cause stroke Overview of Stroke Strokes are a heterogeneous group of disorders involving sudden, focal interruption of cerebral blood flow that causes neurologic deficit. Strokes can be Ischemic (80%), typically resulting... read more or nephropathy Renal Atheroembolism Renal atheroembolism is occlusion of renal arterioles by atherosclerotic emboli, causing progressive chronic kidney disease. It results from rupture of atheromatous plaques. Symptoms are those... read more . Emboli from proximal to distal coronary arteries may cause myocardial infarction Acute Myocardial Infarction (MI) Acute myocardial infarction is myocardial necrosis resulting from acute obstruction of a coronary artery. Symptoms include chest discomfort with or without dyspnea, nausea, and/or diaphoresis... read more .

Coronary artery dissection is also possible.

Access site complications include

Bleeding from the access site may occur and usually resolves with compression. Mild bruises and small hematomas are common and do not require specific investigation or treatment.

A large or enlarging lump should be investigated using ultrasonography to distinguish hematoma from pseudoaneurysm. A bruit at the site (with or without pain) suggests an AV fistula, which can be diagnosed using ultrasonography. Hematomas usually resolve with time and do not require specific therapy. Pseudoaneurysms and AV fistulas usually resolve with compression; those that persist may require surgical repair.

Radial artery access is in general more comfortable for the patient and carries a much lower risk of hematoma or pseudoaneurysm or AV fistula formation when compared with femoral artery access.