Coronary catheterization: Difference between revisions
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[[Coronary artery]] [[lumen|luminal]] [[stenosis|narrowing]] reduces the flow reserve for oxygenated blood to the heart, typically producing intermittent [[Angina pectoris|angina]] if very advanced; [[lumen|luminal]] occlusion usually produces a [[myocardial infarction|heart attack]]. 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]] itself, only significant [[lumen|luminal]] changes which have occurred as a result of end stage complications of the [[atherosclerosis|atherosclerotic]] process. See [[IVUS]] and [[atheroma]] for a better understanding of this issue. | [[Coronary artery]] [[lumen|luminal]] [[stenosis|narrowing]] reduces the flow reserve for oxygenated blood to the heart, typically producing intermittent [[Angina pectoris|angina]] if very advanced; [[lumen|luminal]] occlusion usually produces a [[myocardial infarction|heart attack]]. 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]] itself, only significant [[lumen|luminal]] changes which have occurred as a result of end stage complications of the [[atherosclerosis|atherosclerotic]] process. See [[IVUS]] and [[atheroma]] for a better understanding of this issue. | ||
==Risk Assessment Using Specific Lesion Morphologic Criteria== | ==Risk Assessment Using Specific Lesion Morphologic Criteria== | ||
Revision as of 17:17, 22 August 2013
| Coronary catheterization | |
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| Coronary catheterization:Left coronary artery injection |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Coronary Anatomy
Standard Angiographic Views
How to Assess Epicardial Coronary Blood Flow
How to Assess Myocardial Perfusion
- TIMI myocardial perfusion grade 0
- TIMI myocardial perfusion grade 1
- TIMI myocardial perfusion grade 2
- TIMI myocardial perfusion grade 3
How to Assess Thrombus or Clot
- Complications during and following cardiac catheterization
- Angiogram
- Suggested angiographic projections
- Congenital anomalies of the coronary circulation
- Anomalous origins of coronary arteries
- ST Elevation Myocardial Infarction Coronary Angiography
Coronary catheterization is an 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. Coronary catheterization is one of the several cardiology diagnostic tests and procedures. Specifically, coronary catheterization is a visually interpreted test performed to recognize occlusion, stenosis, restenosis, thrombosis or aneurysmal enlargement the coronary artery lumens, heart chamber size, heart muscle contraction performance and some aspects of heart valve function. Important internal heart and lung blood pressures, 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, atheroma activity within the wall of the coronary arteries. Less frequently, other issues, valvular, heart muscle or arrhythmia issues are the primary focus of the test.[1] [2] [3] [4]
Coronary artery luminal narrowing reduces the flow reserve for oxygenated blood to the heart, typically producing intermittent angina if very advanced; luminal occlusion usually produces a heart attack. 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 itself, only significant luminal changes which have occurred as a result of end stage complications of the atherosclerotic process. See IVUS and atheroma for a better understanding of this issue.
Risk Assessment Using Specific Lesion Morphologic Criteria
Despite the value of risk scores in estimating aggregate procedural risk, there are several limitations of these criteria as applied to individual patients. Identification of lesion characteristics, such as eccentricity, irregularity, angulation, and tortousity, is limited by substantial inter-observer variability. Agreement with ACC/AHA classification was noted in only 58% of lesions in one series, with disagreement by two classification grades noted in nearly 10% of lesions.
Accordingly, rather than a composite score, description of individual morphologic features may be more predictive of early and late outcome following PCI. Some ACC/AHA morphologic features are associated with a complicated procedure (e.g., thrombus, saphenous vein graft [SVG] degeneration, and angulated segments), whereas others are associated with an unsuccessful but uncomplicated procedure (e.g., chronic total occlusions or diffuse disease). As an alternative to providing a composite lesion complexity score, estimation of procedural risk based on the presence of one or more specific adverse morphologic features may be more useful.
Definitions of Preprocedural Lesion Morphology
Feature: Definition
- Eccentricity: Stenosis that is noted to have one of its luminal edges in the outer one quarter of the apparently normal lumen
- Irregularity: Characterized by lesion ulceration, intimal flap, aneurysm, or “sawtooth” pattern
- Ulceration: Lesion with a small crater consisting of a discrete luminal widening in the area of the stenosis is noted, provided it does not extend beyond the normal arterial lumen
- Intimal flap: A mobile, radiolucent extension of the vessel wall into the arterial lumen
- Aneurysmal dilation: Segment of arterial dilation larger than the dimensions of the normal arterial segment
- “Sawtooth pattern”: Multiple, sequential stenosis irregularities
- Lesion length: Measured “shoulder-to-shoulder” in an unforeshortened view
- Discrete Lesion length < 10 mm
- Tubular Lesion length 10–20 mm
- Diffuse Lesion length ≥ 20 mm
- Ostial location: Origin of the lesion within 3 mm of the vessel origin
- Lesion angulation: Vessel angle formed by the centerline through the lumen proximal to the stenosis and extending beyond it and a second centerline in the straight portion of the artery distal to the stenosis
- Moderate: Lesion angulation ≥ 45 degrees
- Severe: Lesion angulation ≥ 90 degrees
- Bifurcation stenosis: Present if a medium or large branch (>1.5 mm) originates within the stenosis and if the side branch is completely surrounded by stenotic portions of the lesion to be dilated
- Lesion accessibility (proximal tortuosity)
- Moderate tortuosity: Lesion is distal to two bends ≥ 75 degrees
- Severe tortuosity: Lesion is distal to three bends ≥ 75 degrees
- Degenerated saphenous vein graft: Graft characterized by luminal irregularities or ectasia comprising > 50% of the graft length
- Calcification: Readily apparent densities noted within the apparent vascular wall at the site of the stenosis
- Moderate: Densities noted only with cardiac motion prior to contrast injection
- Severe: Radiopacities noted without cardiac motion prior to contrast injection
- Total occlusion: TIMI 0 or 1 flow
- Thrombus: Discrete, intraluminal filling defect is noted with defined borders and is largely separated from the adjacent wall; contrast staining may or may not be present
Quantitative Angiography
While “on-line” quantitative angiographic is somewhat cumbersome to use in the catheterization laboratory, “off-line” quantitative angiography has proven invaluable for research investigation in determining the effect of new drugs and devices on lumen dimensions early and late after percutaneous coronary interventions.
Notably, for clinical decision making in intermediate lesions, neither trained visual estimates or on-line quanitative angiography are substitutes for precise physiologic measurements of stenosis severity, such as fractional flow reserve or coronary Doppler measurements.
Computer-Assisted Quantitative Angiography
Quantitative coronary angiography was initiated nearly 30 years ago by Brown and colleagues who magnified 35-mm cineangiograms obtained from orthogonal projections and hand traced the arterial edges on a large screen. After computer-assisted correction for pincushion distortion, the tracings were digitized and the orthogonal projections were combined to form a three-dimensional representation of the arterial segment, assuming an elliptical geometry. While the accuracy and precision were enhanced compared with visual methods, the time needed for image processing limited its clinical use.
Several automated edge-detection algorithms were then developed and applied to directly acquired digital images or to 35-mm cinefilm digitized using a cine-video converter. Subsequent interations of these first degeneration devices have utilized enhanced microprocessing speed and digital image acquisition to render the end-user interface more flexible and substantially shortened the time required for image analysis.
Quantitative coronary angiography is divided into several distinct processes, including film digitization (when applicable), image calibration, and arterial contour detection. For processing 35-mm cinefilm, a cine-video converter is used to digitize images into a 512 × 512 (or larger) × 8-bit pixel matrix. Optical, or less preferred digital, magnification results in an effective pixel matrix up to 2458 × 2458.
Image Calibration
For estimation of absolute coronary dimensions, the diagnostic or guiding catheter is generally used as the scaling device. In general, a nontapered segment of the catheter is selected, and a centerline through the catheter is drawn. Linear density profiles are then constructed perpendicular to the catheter centerline, and a weighted average of the first and second derivative function is used to define the catheter edge points. Individual edge points are then connected using an automated algorithm, outliers are discarded, and the edges are smoothed. The diameter of the catheter is then used to obtain a calibration factor, expressed in millimeters per pixel. The injection catheter dimensions may be influenced by whether contrast or saline is imaged within the catheter tip, and by the type of material used in catheter construction. As the high-flow injection catheters have been developed, more quantitative angiographic systems using contrast-filled injection catheters for image calibration.
Quantitative Coronary Analysis
The automated algorithm is then applied to a selected arterial segment, and absolute coronary dimensions are obtained from the minimal lumen diameter (MLD) reference diameter, and from these, the percent diameter stenoses are derived. For most angiographic systems, interobserver variabilities are 3.1% for diameter stenosis and 0.10 to 0.18 mm for MLD for cineangiographic readings; variabilities are slightly higher (< 0.25 mm) for repeated analyses of the digital angiograms due the the slightly lower resolution compared with cineangiography. The two most commonly used quantitative angiographic systems are described below:
- CARDIOVASCULAR ANGIOGRAPHY ANALYSIS SYSTEM. CAAS (Pie Data Medical B.V., Maastricht, The Netherlands) is a quantitative angiographic system developed for off-line cineangiographic analysis. The edge-detection algorithm incorporates an optional correction for pincushion distortion; its edge detection uses a weighted (50%) sum of the first and second derivatives of the mean pixel density; and it applies minimal cost criteria for smoothing of the arterial edge contours. In addition to reporting a interpolated reference diameter and a minimal lumen diameter (MLD), a subsegment analysis provides mean, minimum, and maximum subsegment diameters. Specific reporting algorithms have been developed for drug-eluting stents, patients undergoing radiation brachytherapy, and in those undergoing peripheral intervention.
- CORONARY MEASUREMENT SYSTEM. (CMS) (MEDIS, Leiden, The Netherlands). Specific features of the CMS include two-point user-defined centerline identification, arterial edge detection using a weighted (50%) sum of the first and second derivatives of the mean pixel density, arterial contour detection using a minimal cost matrix algorithm, and an “interpolated” reference vessel diameter. One limitation of the minimal cost algorithm used with the first-generation CMS (and CAAS-II) system has been its inability to precisely quantify arterial lumen contours characterized by abrupt changes. The CMS-GFT is an algorithm that is not restricted in its search directions, incorporating multidirectional information about the arterial boundaries for construction of the arterial edge that is suitable for the analysis of complex coronary artery lesions. Specific reporting algorithms have been developed for bifurcation lesions, drug-eluting stents, patients undergoing radiation brachytherapy, and in those undergoing peripheral intervention.
Factors Contributing to Variability Using QCA
Variability associated with measurements of the MLD and reference diameter is affected by a number of factors:
- The biologic differences among lumen diameters (e.g., reference vessel size, vasomotor tone, thrombus).
- Inconsistencies in radiographic image acquisition parameters (e.g., quantum mottling, out-of-plane magnification, foreshortening).
- Angiographic measurement variability (e.g., frame selection, factors affecting the edge-detection algorithm). These factors should be controlled in order to improve on the overall diagnostic accuracy of quantitative angiography
Quantitative Angiographic Indices
- Angiographic Success
- Binary Angiographic Restenosis
- Late Lumen Loss
Essentials of Optimal Coronary Angiographic Projections
It is very important that the injection of contrast is delayed until fluoroscopy commences in order to identify calcification or staining of contrast. The acquisition should continue until the contrast has cleared from the arterial tree. Slightly longer acquisition times are needed for evaluation of TIMI Frame Count and TIMI Myocardial Perfusion Grade before and after treatment in percutaneous coronary interventions. Also, an important determinant of the length of injection is the need to visualise collaterals for occluded vessels.
Suggested Angiographic Projections
Congenital Anomalies of the Coronary Circulation
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 to a lesion site. The most commonly used are 0.014 inch diameter guide wires and the balloon dilation catheters, see angioplasty.
By injecting radiocontrast agent through a tiny passage extending down the balloon catheter 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 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 catheters, stent catheters, IVUS catheters, 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 U.S. 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 tissue overgrowth at the lesion site. Restenosis is the body's response to the injury of the vessel wall from angioplasty and to the stent as a foreign body. 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 and paclitaxel are the two 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;
- choosing effective agents,
- developing ways of adequately binding the drugs to the stainless surface of the stent struts (the coating must stay bound despite marked handling and stent deformation stresses) and
- developing coating controlled release mechanisms that release the drug slowly over about 30 days.
Postmortem Angiogram of Coronary Arteries
-
Myocardial Infarction: Postmortem angiogram of coronary arteries -
Angiogram: X-ray, horizontal sections of ventricle showing penetrating artery distribution (a quite good example) -
Angiogram: X-ray, postmortem coronary arteries with multiple lesions -
Angiogram: X-ray postmortem normal coronaries -
Angiogram: Postmortem angiogram with apparent lesions in proximal right coronary artery -
Angiogram: X-ray, postmortem injection horizontal slice of left ventricle showing very well penetrating arteries -
Angiogram Saphenous Vein Bypass Graft: X-ray shows rather close-up large vein anastomosing to much smaller artery -
Angiogram Saphenous Vein Bypass Graft: X-ray postmortem injection showing vein anastomosis very well and the vasculature of the right and left ventricles -
Coronary artery: Atherosclerosis: X-ray postmortem extensive lesions in this x-ray of whole heart -
X-Ray Intramyocardial Arteries: X-ray three horizontal slices of ventricles showing quite well the penetrating arteries -
X-Ray Intramyocardial Arteries: X-ray three horizontal slices of ventricles showing quite well the penetrating arteries -
Coronary Artery Anomalous Origin; Left From Pulmonary Artery: Angiogram, postmortem, after switch of left coronary artery to aorta -
Coronary artery: Atherosclerosis: X-ray, postmortem, dissected arteries and extensive lesions -
Coronary artery: Atherosclerosis: X-ray, postmortem, close-up view of artery with extensive lesions (very good example) -
Coronary artery: Atherosclerosis: X-ray, postmortem, dissected artery, lesions in small branches
Related Chapters
- Interventional cardiology
- Cardiology
- TIMI flow grade 0
- TIMI flow grade 1
- TIMI flow grade 2
- TIMI flow grade 3
- TIMI frame count (TFC)
- TIMI myocardial perfusion grade 0
- TIMI myocardial perfusion grade 1
- TIMI myocardial perfusion grade 2
- TIMI myocardial perfusion grade 3
- Thrombus Grading
- Complications during and following cardiac catheterization
- Access site complications
- Angiogram
- Suggested angiographic projections
- Congenital anomalies of the coronary circulation
- Anomalous origins of coronary arteries
- ST Elevation Myocardial Infarction Coronary Angiography
References
- ↑ 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.
- ↑ Smith SC Jr, Feldman TE, Hirshfeld JW Jr, Jacobs AK, Kern MJ, King SB 3rd, Morrison DA, O'neill WW, Schaff HV, Whitlow PL, Williams DO, Antman EM, Smith SC Jr, Adams CD, Anderson JL, Faxon DP, Fuster V, Halperin JL, Hiratzka LF, Hunt SA, Jacobs AK, Nishimura R, Ornato JP, Page RL, Riegel B; American College of Cardiology/American Heart Association Task Force on Practice Guidelines; ACC/AHA/SCAI Writing Committee to Update the 2001 Guidelines for Percutaneous Coronary Intervention. ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention-Summary Article: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/SCAI Writing Committee to Update the 2001 Guidelines for Percutaneous Coronary Intervention). J Am Coll Cardiol. 2006 Jan 3;47(1):216-35. PMID 16386696
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