Angiographic Data

4 Angiographic Data

Angiograms are the most important product of cardiac catheterization and often the most important tests that patients with cardiac disease will undergo. The risks of angiography are serious but fortunately rare. Nonetheless, operators must take special care in the performance of coronary, ventricular, and peripheral vascular angiography. The expert angiographer must be concerned, competent, and experienced. The radiographic images are the visual representation of the vascular network connected to internal structures (organs) and, at times, predict the function of the circulation. Experienced operators obtain good-quality images without increasing the ordinary procedural radiation exposure to either the patient or the catheterization laboratory personnel.

Optimal angiographic data collection is a process of linked steps. Failure of any link breaks the chain and may cause loss of all or part of the data. The chain begins with the nurse’s positioning the patient on the table, followed by catheter placement and correct imaging views, the display of the image for review, and finally the recording and storing of the digital image for the archives. The major causes of poor angiograms include factors specific to the patient (size, hardware), angiographic technique, equipment-related problems, and optical and digital imaging system issues (Table 4-1).

Table 4-1 Causes for Poor Angiograms

Patient Factors
Hardware (pacemaker, Harrison rods, multiple surgery with clips, silicone prosthesis)
Anatomic conditions (scoliosis, scarred lungs, large heart [fluid])
Angiographer Factors
Poor catheter seating (wrong catheter shape, size, anomalous origin, subselective cannulation)
Poor contrast opacification (weak injection, volume too small, diluted contrast material)
Equipment Factors
X-ray generator problems (high heat, quantum mottle, too high kilovoltage, too short pulse width, too long pulse width)
X-ray tube problems (anode pitting, wrong focal spot, beam geometry, proximity to image intensifier, poor collimation)
Digital imaging program malfunction

Coronary Angiography

The goal of coronary angiography is to visualize the coronary arteries, branches, collaterals, and anomalies with enough detail to make a precise diagnosis of and plan the treatment strategy for coronary artery disease. With percutaneous coronary interventions (PCIs, e.g., stents), the coronary angiographer is expected to document not only the presence of disease but also its precise location relative to major and minor side branches, thrombi, and areas of calcification in detail. For PCI, visualization of vessel bifurcations, origin of side branches, the portion of the vessel proximal to a significant lesion, and specific lesion characteristics (e.g., length, eccentricity, calcium) is crucial. In the case of a total vessel occlusion, the distal vessel should be visualized as clearly as possible. This is achieved by opacifying the coronary arteries, supply collaterals, which with radiographic contrast medium and taking cineangiograms (that are long enough while panning across the heart) to visualize late collateral vessel filling and length of the occluded segment. Visualizing the collateral supply vessels helps determine the revascularization strategy.

The routine coronary angiographic views should include visualization of the origin and course of the three major vessels and their branches in at least two different planes. Coronary anatomy varies widely, and appropriately modified views must be individualized.

Contrast Media Injection Techniques—Power Versus Hand Injection

Contrast medium, a viscous, iodinated solution used to opacify the coronary arteries, can be injected by hand through a multivalve manifold. The tip of the syringe is kept pointed down (handle raised up) so that any small bubbles float up and are not injected into the circulatory system (Fig. 4-1). Flow rates are usually 2 to 4 ml/sec with volumes of 2 to 6 ml in the right coronary artery (RCA) and 7 to 10 ml in the left coronary artery (LCA). Hand injection has been used successfully for many years. The use of disposable manifolds, syringes, and tubing is cost effective and safe.

Power injection of the coronary arteries has been used in thousands of cases in many laboratories and is as safe as hand injection. A power injector at a fixed setting might require several injections to find the optimal contrast delivery flow rate. Power injectors now incorporate hand controls, permitting precise operator touch-sensitive variable volume injectors (Acist; Bracco Diagnostics, Med-Rad, etc.), and a computer touch screen for precise contrast delivery settings (Fig. 4-2). The system is highly effective at opacification of arteries through small diameter catheters (<5 F). In addition it is also highly cost affective with the contrast reservoir. Typical settings for power injections are as follows:

Angiographic View Setup Keys

“The best panning is no panning.” Panning motion often overshoots the image targets and information is lost. One key to accurate, optimal coronary cineangiography, obtaining the most information for the least amount of movement, is the initial setup of the catheter on the fluoroscope screen. Figure 4-3 shows the catheter–left main artery setup keys for left anterior oblique (LAO) views in the straight (anteroposterior [AP]), cranial, and caudally angled projections. When the patient is positioned correctly and the setup key followed, only minimal panning is necessary to obtain the information. In the LAO view the operator pans down the left anterior descending (LAD) artery then rightward to identify collaterals going to the right coronary artery (RCA). If the circumflex (CFX) is occluded, then leftward panning will include collaterals going to the distal CFX artery. For the RCA, in the LAO position, the operator pans downward and to the left toward the LAD artery. This will visualize late filling collaterals from the right coronary system to the LAD artery. These motions are diagrammed in Figure 4-3.

In the right anterior oblique (RAO) projections for the LCA and RCA, the operator pans downward to the apex to identify late filling, left-to-left or right-to-left collaterals. The initial setup keys for catheter tip position on the fluoroscope are summarized in Table 4-2, help the operator include all crucial information for coronary angiography.

Table 4-2 Setup Key Locations for Angiographic Views

Artery View Setup Region on Angulation Grid (below) (No.) Comment
LAD LAO cranial 2 Set up on screen
  LAO caudal 5 Top, mid line
  RAO cranial 1 Top, left upper coronary
  RAO caudal 4 Middle, left side
RCA LAO cranial/caudal 1, 2 Left upper coronary
  RAO cranial/caudal 1, 4 Left upper coronary
LAD/RCA AP Cranial 2  

AP, Anteroposterior; LAD, left anterior descending; LAO, left anterior oblique; RAO, right anterior oblique; RCA, right coronary artery.

Fluroscreen grid.

1 2 3
4 5 6
7 8 9

Nomenclature of Angiographic Imaging Views

To obtain optimal information from coronary cineangiography, the operator must use various angulations, unveiling overlapped vessel segments. These views or projections highlight specific and distinct segments of the coronary anatomy and permit discrete visualization of underlying pathologic conditions. Understanding of the usefulness of various radiographic views (and nomenclature) is essential.

For all catheterization laboratories the x-ray source is under the table, and the image intensifier is directly above the patient. The source and image intensifier (also known as a flat panel detector in fully digital laboratories) are moving in opposite directions in an imaginary circle around the patient positioned in the center. The body surface of the patient which faces the observer, determines the specific view. This relationship holds true whether the patient is supine, standing, or rotated (Fig. 4-4).

Cranial and caudal views are used to “open” overlapped coronary segments that are foreshortened or obscured in regular views. Note: Cranial views are best for the LAD artery; caudal views are best for the CFX arteries.

The rationale for these routine angiographic views is as follows. Tables 4-3 and 4-4 suggest best setup for visualizing the specific coronary artery.

Table 4-3 Recommended “Key” Angiographic Views for Specific Coronary Artery Segments

Coronary Segment Origin and Bifurcation Course Through Body
Left main AP AP
  LAO cranial LAO cranial
  LAO caudal  
Proximal LAD LAO cranial LAO cranial
  RAO caudal RAO caudal
Mid LAD LAO cranial  
  RAO cranial  
Distal LAD AP  
  RAO cranial  
Diagonal LAO cranial RAO cranial, caudal, or straight
Proximal circumflex RAO cranial  
  RAO caudal LAO caudal
  LAO caudal  
Intermediate RAO caudal RAO caudal
  LAO caudal Lateral
Obtuse marginal RAO caudal RAO caudal
  LAO caudal  
  RAO cranial (distal marginals)  
Proximal RCA LAO  
  Lateral Lateral
Distal RCA LAO cranial LAO cranial
  Lateral Lateral
PDA LAO cranial RAO
Posterolateral LAO cranial RAO
  RAO cranial RAO cranial

AP, Anteroposterior; LAD, left anterior descending artery; LAO, left anterior oblique; PDA, posterior descending artery (from RCA); RAO, right anterior oblique; RCA, right coronary artery.

Horizontal hearts.

Table 4-4 Routine Coronary Angiographic Views

Left Coronary Artery For Concentration on Vessel Segment
Straight AP or 5 degrees to 10 degrees RAO with caudal Left main
30 degrees to 45 degrees LAO and 20 degrees to 30 degrees cranial LAD-circumflex bifurcation
30 degrees to 40 degrees RAO and 20 degrees to 30 degrees caudal Circumflex + marginal branches
5 degrees to 30 degrees RAO and 20 degrees to 45 degrees cranial LAD + diagonals
50 degrees to 60 degrees LAO and 10 degrees to 20 degrees caudal (spider view) LAD-circumflex bifurcation, circumflex, marginals
Lateral (optional) Bypass conduits to LAD
Right Coronary Artery For Concentration on Vessel Segment
30 degrees to 45 degrees LAO and 15 degrees to 20 degrees cranial Proximal, mid, PDA
30 degrees to 45 degrees RAO Proximal, mid, PDA
Lateral (optional)  

AP, Anteroposterior; LAD, left anterior descending artery; LAO, left anterior oblique; PDA, posterior descending artery (from right coronary artery); RAO, right anterior oblique.

Note: The lateral view is a useful addition to these views for both coronary arteries. In addition, the four most common views for the left coronary artery when performed LAO cranial, RAO cranial, RAO caudal, and LAO caudal form a box around the patient. Look first at the LAD (cranial views) and then at the circumflex (caudal views). This box should be on every study with rare exceptions.

Left Coronary Artery

1. The AP caudal or shallow RAO view displays the left main coronary artery (LMCA) in its entire perpendicular length (Figs. 4-5, 4-6, 4-7, and 4-8). In this view, the proximal segments of the LAD and left CFX arteries are displayed, but the branches are overlapped. After the left main segment, slight RAO or LAO angulation may be necessary to clear the density of the vertebrae and the catheter shaft in the thoracic descending aorta from covering the artery.

Usefulness of Biplane Coronary Angiography

Simultaneous biplane cineangiography, although uncommonly used, provides accurate images from two different simultaneous points of view and is advantageous in performing complete coronary or ventriculography with reduced contrast volumes and radiation exposure. Biplane angiography helps to unravel complex coronary or structural cardiac anatomy (Table 4-5). Biplane angiography is most useful in the pediatric population and those patients with renal failure. Biplane is advocated in some adult interventional procedures like complex electrophysiologic mapping or novel structural heart disease implant device placements (e.g., ventricular septal defect (VSD) occluders).

Table 4-5 Biplane Coronary Angiography


Disadvantages (depending on experience)

Major limitations or objections by operators:

Method to overcome these objections:

The value of biplane information must be balanced against cost and difficulty of use. The traditional set up for biplane coronary angiography required the patient’s heart to be in the exact center of the two planes (the isocenter) and then the AP and lateral planes were angled in orthogonal projections (e.g., LAO-cranial and RAO-caudal, Fig. 4-9) This setup often resulted in more difficulties than it solved. Depending on the team, operator frustration increased with the perceived additional set up and procedure time needed to center the patient and repeat images that were lost when panning in one plane and out of the other. The potential savings of contrast media and radiation exposure were also lost when the two orthogonal planes were not perfectly positioned.

A novel setup makes biplane angiography simple, quick, and effective. The method uses concordant cranial or caudal imaging views such as cranially angled LAO/RAO projections and then moving both C-arms to caudally angled LAO/RAO projections (see Fig. 4-9). In this way, angiographic information is not lost when panning because the heart moves in a similar direction albeit from the opposite side (but not cranial versus caudal). With the concordant biplane setup, contrast use was halved, the radiation dose reduced, and the procedure time shortened.

Biplane coronary angiography has not been generally considered critical for routine studies. However, if the laboratory has biplane capability, it should consider improving procedure times, contrast use, and information quality. Some initial orientation is necessary to start biplane imaging. One should spend a minute finding true isocenter in two simple steps: (1) center the heart under the AP tube and (2) bring in the lateral tube and center the heart by raising or lowering the table. Next, the operator should position the planes LAO/RAO and then angle both tubes cranially. This can then proceed to moving both tubes to caudal projections (concordance of cranial/caudal angulations).

Biplane angiography may provide additional information documenting the true path of anomalous coronary arteries beyond single plane imaging. For example, Wang et al (Cathet Cardiovasc Intervent 42; 73-78, 1997) used the biplane images and confidently demonstrated the several potential courses of the anomalous Left main artery (the retroaortic course, intraarterial, and anterior looping or intraseptal courses). The levophase of the ascending aorta also provides a good view of the posterior aortic wall further assisting in determining the course of the coronary artery. Biplane was helpful to obtain the “dot and eye” assessment of the anomalous left main (LM) from the right sinus of Valsalva with fewer views required (see Serota et al).

Assessment of Coronary Stenoses

Assessment of the Degree of Narrowing

The degree of an angiographic narrowing (stenosis) is reported as the estimated percentage lumen reduction of the most severely narrowed segment compared with the adjacent angiographically normal vessel segment, seen in the worst x-ray projection. Because the operator uses visual estimations, an exact evaluation is impossible. There is a ± 20% variation between readings of two or more experienced angiographers. Stenosis severity alone should not always be assumed to be associated with abnormal physiology (flow) and ischemia. Moreover, coronary artery disease is a diffuse process and thus minimal luminal irregularities on angiography may represent significant albeit nonobstructive CAD at the time of angiography. The stenotic segment lumen is compared with a nearby lumen that does not appear to be obstructed but that may have diffuse atherosclerotic disease (Fig. 4-10). This explains why postmortem examinations and intravascular ultrasound imaging (IVUS) describe much more plaque than is seen on angiography. The percent diameter is estimated from the angiographically normally adjacent segment. Because coronary arteries normal taper as they travel to the apex, proximal segments are always larger than distal segments, often explaining the large disparity among several observers’ estimates of stenosis severity. Area stenosis is greater than diameter stenosis and assumes the lumen is circular, whereas the lumen is usually eccentric. In general, four categories of lesion severity can be assigned:

Technical note: Stenosis anatomy should not be confused with abnormal physiology (flow) and ischemia, especially for lesions 40% to 70% narrowed. For nonquantitative reports, the length of a stenosis is simply mentioned (e.g., LAD proximal segment stenosis diameter 25%, long or short). Other features of the coronary lesion may not be appreciated by angiography and require IVUS (Fig. 4-11).

Classification of Angiographic Blood Flow (TIMI Grades)

Angiographic blood flow has been qualitatively assessed by observing the distal runoff and is classified into four grades (also known as TIMI flow grades). The TIMI grade was developed from the Thrombolysis in Myocardial Infarction Studies in the late 1980s.

The four grades of flow are described as follows:

In acute myocardial infarction trials, TIMI grade 3 flows have been associated with improved clinical outcomes. The quantitative method of TIMI flow uses cineangiography with 6 F catheters and filming at 30 frames per second. The number of cine frames from the introduction of dye in the coronary artery to a predetermined distal landmark is counted. The TIMI frame count for each major vessel is thus standardized according to specific distal landmarks. The first frame used for TIMI frame counting is that in which the dye fully opacifies the artery origin and in which the dye extends across the width of the artery touching both borders with antegrade motion of the dye. The last frame counted is when dye enters the first distal landmark branch. Full opacification of the distal branch segment is not required. Distal landmarks used commonly in analysis are (1) for the LAD, the distal bifurcation of the LAD artery; (2) for the CFX system, the distal bifurcation of the branch segments with the longest total distance; and (3) for the right coronary artery, the first branch of the posterolateral artery. The TIMI frame count can further be quantitated for the length of the LAD coronary artery for comparison the two other major arteries; this is called the corrected TIMI frame count (CTFC). The average LAD coronary artery is 14.7 cm long, the right 9.8 cm, and the CFX 9.3 cm, according to Gibson and colleagues. CTFC accounts for the distance the dye has to travel in the LAD relative to the other arteries. CTFC divides the absolute frame count in the LAD by 1.7 to standardize the distance of dye travel in all three arteries. Normal TIMI frame count (TFC) for LAD is 36 ± 3 and CTFC 21 ± 2; for the CFX, TFC = 22 ± 4; for the RCA, TFC = 20 ± 3. Neither TIMI flow grades nor CTFC correspond to measured Doppler flow velocity. High TFC may be associated with microvascular dysfunction despite an open artery. CTFC of <20 frames was associated with low risk for adverse events in patients following myocardial infarction. A contrast injection rate increase of ≥1 mL/sec by hand injection can decrease the TIMI frame count by two frames. The TIMI frame count method provides valuable information relative to clinical responses after coronary interventions.

Myocardial tissue perfusion by angiography has been estimated by a perfusion blush score, which has been proposed by Gibson et al (see references).

Problems and Solutions in the Interpretation of Coronary Angiograms

Special Problems

Left Main Coronary Artery Stenosis

A commonly encountered and potentially critical problem is safe coronary angiography of patients who have LMCA stenosis (Fig. 4-12). The approach to the patient with LMCA stenosis is one of the few situations in which the operator and team may directly affect the life and death of the patient. The LM stenosis may occur at the ostium, mid-body, or distal bifurcation of LAD/CFX and has implications for coronary artery bypass graft (CABG) and PCI decisions.

LMCA stenosis is commonly associated with two clinical presentations:

Technical notes for the angiography of the LMCA stenosis:

5. After catheter engagement the operator should look for aortic pressure wave deformation (damping). If pressure damping occurs, a limited contrast flush (1 to 2 ml) and rapid catheter withdrawal (“hit and run”) during cineangiography should be performed to obtain a first look (Fig. 4-13). Rarely, aortic pressure damping occurs without LMCA narrowing because the coronary catheter is seated deeply and subselectively into the LAD artery. Gradual withdrawal and repositioning of the catheter may eliminate pressure damping. The absence of reflux of contrast media into the aortic root on coronary injection is associated with an ostial LMCA stenosis.

Left Ventriculography in Patients with Left Main Coronary Artery Stenosis

In patients with LMCA stenosis, noninvasive imaging techniques (two-dimensional and Doppler echocardiography, radionuclide angiography) to determine left ventricular (LV) function and mitral regurgitation may replace LV angiography. Safe contrast ventriculography can be performed with the use of low-volume (<30 ml) nonionic, low-osmolar contrast medium, facilitating a rapid “one-test (coronary angiogram and left ventriculogram)” surgical decision. Careful LV catheter manipulation, including the pigtail catheter (especially in patients with LMCA stenosis and unstable angina), will prevent a benign, transient arrhythmia from becoming a catastrophe. Left ventriculography should be considered only for patients who have a low risk/benefit ratio.

Important points for postcatheterization care of the patient with LMCA stenosis:

Angiography of Common Coronary Anomalies

Misdiagnosis of an unsuspected anomalous origin of the coronary arteries is a potential problem for a busy angiographer. Because the natural history of a patient with an anomalous origin of a coronary artery may depend on the initial course of the anomalous vessel, it is the angiographer’s responsibility to define accurately the origin and course of the vessel. It is an error to assume that a vessel is occluded when it has not been visualized because of an anomalous origin. Even experienced angiographers have difficulty delineating the true course of the anomalous vessel. Although computerized tomographic angiography (CTA) is a superior technique to angiography, the diagnosis often is still required in the catheterization laboratory.

For the most critical anomaly, the left main anomalous origin from the right cusp, a simple “dot and eye” method for determining the proximal course of the anomalous artery from RAO ventriculogram, RAO aortogram, or selective RAO injection is proposed. The RAO view best separates the normally positioned aorta and pulmonary artery (PA). Placement of right-sided catheters or injection of contrast material into the PA is unnecessary and often misleading.

Anomalous Origin of the Left Main Coronary Artery from the Right Sinus of Valsalva

When the LMCA arises from the right sinus of Valsalva or the proximal RCA, it may follow one of four pathways:

1. Septal course. The LMCA runs an intramuscular course through the septum along the floor of the right ventricular (RV) outflow tract (Fig. 4-14). It then surfaces in the mid septum, at which point it branches into the LAD artery and left CFX artery. Because the artery divides in the mid-septum, the initial portion of the CFX artery courses toward the aorta (the normal position of the proximal LAD), and the LAD artery is relatively short (i.e., only mid and distal LAD are present). During RAO ventriculography, aortography, or coronary angiography the LMCA and the CFX coronary artery form an ellipse (similar to the shape of an eye) to the left of the aorta. The LMCA forms the inferior portion and the CFX artery forms the superior portion. Septal perforating arteries are evident branching from the LMCA.

2. Anterior free wall course. The LMCA crosses the anterior free wall of the right ventricle, and then divides at the mid-septum into the LAD and CFX arteries (Fig. 4-15). Because the artery divides at the mid septum, the initial portion of the CFX artery courses toward the aorta (the normal position of the proximal LAD), and the LAD artery is relatively short (i.e., only mid and distal LAD are present). During RAO ventriculography, aortography, or coronary angiography, the LMCA and the CFX artery form an ellipse (“eye”) to the left of the aorta with the LMCA forming the superior portion and the CFX forming the inferior portion.

3. Retroaortic course. The LMCA passes posteriorly around the aortic root to its normal position on the anterior surface of the heart (Fig. 4-16). It divides into the LAD and CFX arteries at the normal point and gives rise to LAD and CFX coronary arteries of normal length and course. During RAO ventriculography, aortography, or coronary angiography, the LMCA is seen “on end,” posterior to the aorta, and appears as a radio-opaque dot. This retroaortic dot signifies a posteriorly coursing anomalous vessel. (It is also seen with anomalous origin of CFX from right sinus.)

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Jun 4, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Angiographic Data

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