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The Role and Impact of Thrombus in Formation and Revascularization of Chronic Total Occlusions Chapter | 21 315
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amenable to thrombolysis [12,13]. In the absence of bleeding complications, low-dose thrombolytic therapy can be
continued until complete thrombus removal occurs and then consideration must be given to completion of the revascularization, usually by means of stenting.
REVASCULARIZATION TOOLS FOR CHRONIC TOTAL OCCLUSION
Revascularization of a CTO first requires engagement with a supporting guiding catheter. Then the CTO can be crossed
with a dedicated guidewire either via the antegrade approach (from the ascending aorta onto the coronary artery), i.e.,
aiming to directly cross the proximal cap [8] of the CTO, or via the retrograde contralateral approach [14] through collaterals that retrogradely perfuse the distal vessel that contains the CTO. In this scenario the distal cap is first traversed by
the guidewire, which is advanced retrogradely along the native vessel toward the proximal cap and then crosses beyond
onto the ascending aorta. For this task operators use specially designed guidewires with the unique capability to penetrate a
CTO. In many instances wire escalation techniques are required. Hence, the thrombus within a CTO offers an improved
route of crossing through its microchannels. Consequently, as the thrombus yields to manipulations of the guidewire tip it
permits guidewire traversing.
For the removal process of atherosclerotic and thrombotic content within CTOs, multiple dedicated and innovative
technologies are available. These include standard, coated, and fortified cutting balloons; balloon-mounted radio frequency
combined with thermal energy; acoustic ultrasound energy catheters; vibrational energy; magnetic navigation; blunt
microdissection catheters; and collagenase infusion. Two of the most prominent debulking and thrombus removal tools are
rheolytic atherectomy (AngioJet, Boston Scientific, Boston, MA, USA) and the excimer laser (Spectranetics, Colorado
Springs, CO, USA). Both technologies utilize direct thrombus engagement for removal of its constituents.
AngioJet
The principle of activation for rheolytic thrombectomy is based on the creation of saline jets inside the catheter, which
travel backward from the tip at very high speed, creating a negative pressure zone from the Venturi effect. Side holes along
the catheter’s tip optimize fluid flow and draw the thrombus into the catheter for fragmentation and removal by suction into
a collecting container [15]. The rheolytic thrombectomy contains a special mechanical function termed “power spray,”
which infuses tissue plasminogen activator (tPA) or other thrombolytic agents from the tip of the device directly onto the
targeted thrombus during activation. This offers a combined pharmacologic thrombolytic effect with powerful mechanical
extraction, a synergistic strategy aptly termed “power thrombectomy” [16]. Totally occluded saphenous vein grafts (SVGs)
accountable for ischemic myocardium can be approached as well. For this task we introduced a unique revascularization
technique, which incorporates thrombectomy devices termed “SVG sculpturing” [17] (Fig. 21.5). Other power-based
thrombus removal technologies such as the laser can conveniently be incorporated with rheolytic thrombectomy along
with the SVG sculpturing strategy.
Excimer Laser
The pulsed, “cold,” ultraviolet wavelength (308 nm) laser is an optimal device for CTO revascularization, due to unique
photoablative effects on atherosclerotic plaques. The excimer laser is capable of debulking both the atherosclerotic substrate and the thrombotic material within a CTO [18]. Clinically, the excimer laser has been found a useful interventional
tool for targeted thrombus removal strategy [19]. The physical process caused by the laser activation is the creation of
acoustic shock waves that propagate along the irradiated vessel. These waves carry a dynamic pressure front, which
collides with the fibrin mesh within the thrombus. The process disrupts and breaks the fibrin fibers, resulting in fibrinolysis
and decreased thrombus size [20]. This laser also alters the aggregation kinetics of platelets, causing a reduction of platelet
force development and inhibition of the platelet activity. This phenomenon of platelet stunning is dose dependent and most
pronounced at high levels of energy fluence, such as 60 mJ/mm
the CTO lesions and facilitate adjunct balloon and stenting [22]. High success rates of 86%e90% for the excimer have
been reported in these occlusions [23]. Total occlusions are mostly long-standing lesions that contain layers of old, wellorganized thrombus within calcified and fibrotic plaques. The setting of acute myoca rdial infarction attributed to a CTO
can present a specific challenge because of a large, fresh thrombus burden imposed on an underlying CTO plaque. In such
instances the laser can be used successfully for recanalization of the target [24].
2
[21]. Either a laser catheter or a laser wire can penetrate
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(A)
(C)
(B)
(D)
FIGURE 21.5 The sculpturing percutaneous intervention technique for revascularization of chronic total occlusion of a saphenous vein graft (SVG). The
patient underwent coronary artery bypass surgery twice in the past. He presented with several weeks’ duration of unstable angina pectoris. Significant
inferiorelateral ischemia was noted. A third-degree atrioventricular block developed, accompanied by hypotension and worsening chronic renal failure. A
year earlier both the right coronary artery and its corresponding saphenous vein bypass graft angiographically demonstrated complete occlusion. (A) An 8Fr multipurpose guide with side holes positioned firmly at the ostium of the occluded SVG (arrow). (B) Advancement of a Whisper guidewire (Abbott
Vascular, Temecula, CA, USA) into the proximal portion of the graft met resistance. The guidewire support was then enhanced with a dedicated catheter
(QuickCross, Spectranetics, Colorado Springs, CO, USA). (C) Guidewire reaching the distal anastomosis site (arrow). This guidewire was exchanged with
a sturdy Platinum Plus supporting guidewire (Boston Scientific, Boston, MA, USA). (D) Rheolytic thrombectomy catheter (arrow) slowly activated in an
antegrade and retrograde thrombus removal movement along the occluded graft. The AngioJet retrieved a large thrombotic content. (E) Angiogram of the
recanalization after initial thrombectomy. (F) Selective administration of 20 mg (TPA) into the SVG through a dedicated ClearWay perfusion catheter
(arrow). (G) Angiogram after 20 min of tissue plasminogen activator dwelling time in the SVG. (H) Final angiogram after stenting of the SVG’s body and
the distal anastomosis site. TIMI 3 flow was restored, accompanied by alleviation of chest pain and ischemia, achievement of hemodynamic stability, and
restoration of a baseline rhythm of first-degree arteriovenous block. Following the SVG sculpturing procedure the renal function improved from creatinine
of 3.1 to the chronic baseline of 2.0. TIMI, thrombolysis in myocardial infarction.
Stents
Most procedures of PCI or endovascular peripheral interventions for CTOs include a final step of stenting. The preferable
stent for this task is the drug-eluting type. In select patients with markedly long coronary CTOs the intervention may
require implantation of a “full metal jacket,” i.e., final stent length of 60 mm or longer without a gap, to provide complete
lesion coverage [25].
The Role and Impact of Thrombus in Formation and Revascularization of Chronic Total Occlusions Chapter | 21 317
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(E)
(G)
(F)
(H)
FIGURE 21.5 cont’d
CHRONIC TOTAL OCCLUSION IN PERIPHERAL ARTERIAL DISEASE
Critical limb ischemia (CLI) is frequently associated with severe atherosclerotic disease of the aortoiliac vasculature and
beyond to include the infragenicular arteries. The disease is represented by long total occlusions containing a large
thrombus content [11].
Shammas and colleagues have gained a large experience with several technologies for revascularization of peripheral
CTOs. These investigators utilized the AngioJet rheolytic thrombectomy device in CTOs, combining its dual capability of
power-pulse tPA spray and mechanical thrombus extraction. This revascularization approach was utilized in the DETHROMBOSIS registry, which aimed at thrombus removal in the lower extremity arteries in patients with recent-onset limb
ischemia due to total occlusion of at least one infrainguinal vessel (less than 6 months old) [26]. The interventionalists also
successfully applied the excimer laser for treatment of chronic and subacute thrombotic occlusions of the lower extremity
peripheral arteries [27]. A beneficial experience with the laser was reported as well by other interventionalists [28e31].A
strategy incorporating the excimer laser in the peripheral arterial clinical scenario is beneficial for reasons similar to those
regarding revascularization of CTO in coronary arteries (Fig. 21.6). Advantages of the laser incl ude facilitation of lesion
crossing, removal of the occlusive or resistant atherosclerotic plaque burden, vaporization of underlying thrombus, and
creation of a “pilot channel,” i.e., an intraplaque tunnel-like recanalization channel, which enables easy delivery and
accurate positioning of a balloon for adjunct dilatations [30]. A substantial reduction in distal embolization from the total
occlusion site and a reduced need for stenting in the infrapopliteal arteries are observed. A subset of patients with CTOs
refractory to guidewire canalization was selected for analysis from the LACI 2, the LACI CIS, and the LACI Belgium trials
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(A)
(B)
FIGURE 21.6 Percutaneous intervention incorporating excimer laser debulking and adjunct stenting for a symptomatic patient with chronic total oc-
clusion (CTO) of the superficial femoral artery (SFA). (A) Total occlusion of the vessel by a CTO with typical distal reconstitution of the circulation at the
popliteal artery through collaterals. (B) Complete patency of the SFA following the CTO revascularization with the excimer laser and adjunct stent.
Excellent flow fills the entire target vessel. Corresponding clinical improvement was noted. With permission from Singh GD, Armstrong EJ, Laird JR.
Laser revascularization for critical limb ischemia. In: Topaz O, editor. Lasers in cardiovascular interventions. London, UK: Springer; 2015, pp
141e156.
[32]. Altogether, 46 patients who experienced CLI with Rutherford category 4e6, in 47 limbs and with 205 lesions (67%
in the superficial femoral artery, 11% in the popliteal artery, and 20% in infrapopliteal arteries) averaging 73.4 7.3 mm in
length (mean 4.4 lesions per limb), were treated with excimer laser angioplasty. The step-by-step lasing technique was
utilized during attempts to cross the occlusions with a guidewire. Procedural success was 72%, a straight-line flow to the
foot was established in 79%. Limb salvage was achieved in 95% of 42 surviving patients. The operators stressed the fact
that this high rate of limb salvage was achieved in a group of patients with complex medical issues who otherwise would
have had required limb amputation.
SUMMARY
Thrombus plays a major role in the formation and histopathologic structure of CTO lesions in arteries and old SVGs. A
nonocclusive thrombus can be formed by silent plaque rupture or erosion. As the thrombus increases in size to become
flow occlusive, a process of healing forms the CTO. Consequently, the provisional matrix at healed lesions is an organized
thrombus, which may contain fibrin and be infiltrated by smooth muscle cell granulation tissue with proteoglycans and type
III collagen. Then the thrombus proximal and distal to the site of plaque rupture is replaced by fibrous plaque. For
revascularization, the presence of microchannels within the thrombus enables guidewire crossing which, in turn, promotes
delivery of mechanical tools for plaque removal and stenting. Altogether, thrombus layers within the CTO lesions
The Role and Impact of Thrombus in Formation and Revascularization of Chronic Total Occlusions Chapter | 21 319
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constitute an anatomic morphologic route for targeted percutaneous treatment and serve as a strong predictor of success in
revascularization of coronary and peripheral arterial CTOs.
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[2] Strivatsa SS, Edwards WD, Boos CM, et al. Histologic correlates of angiographic chronic total coronary artery occlusions: influence of occlusion
duration on neovascular channel patterns and intimal plaque composition. J Am Coll Cardiol 1997;29:955e63.
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lization. 2nd ed. Chichester, UK: Wiley-Blackwell; 2013. p. 3e9.
[4] PUMA A, Sketch Jr MH, Tcheng JE, et al. Percutaneous revascularization of chronic coronary occlusions :an over-view. J Am Coll Cardiol
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[5] Grantham JA, Marso SP, Spertus J, et al. Chronic total occlusion angioplasty in the United States. JACC Cardiovasc Interv 2009;2:479e86.
[6] Christofferson RD, Lehmann KG, Martin GV, et al. Effect of chronic total coronary occlusion on treatment strategy. Am J Cardiol
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[7] Edwards JE. Atherosclerotic lesions: their distribution and histopathology. In: Budinger TF, editor. Noninvasive techniques for assessment of
atherosclerosis in peripheral, carotid and coronary arteries. New York: Raven Press; 1982. p. 1e13.
[8] Topaz O. Revascularization of the impenetrable CTO-in support of the enhanced antegrade approach. Cath Cardiovasc Interv 2009;73:276e7.
[9] Suzuki Y, Tsuchikane E, Katoh O, Muramatsu T, Muto M, Kishi K, Hamazaki Y, Oikawa Y, Kawasaki T, Okamura A. Outcomes of percutaneous
coronary interventions for chronic total occlusion performed by highly experienced Japanese specialists: the first report from the Japanese CTO-PCI
Expert Registry. JACC Cardiovasc Interv 2017;10:2144e54.
[10] Abbott JD, Vlachos HA, Sawhney N, et al. Recent trends in the percutaneous treatment of chronic total coronary occlusions. Am J Cardiol
2006;97:1691e6.
[11] Murarka S, Heuser R. Recanalizing total occlusion in the periphery: utilization of radio frequency and other technology. In: Waksman R, Saito S,
editors. Chronic total oclusions-a guide to recanalization. 2nd ed. Chichester, West Sussex, UK: Wiley-Blackwell; 2013. p. 209e29.
[12] Wholey MH, Maynor MA, Wholey Jr MH, et al. Comparison of thrombolytic therapy of lower acute, subacute and chronic arterial occlusions.
Cathet Cardiovasc Diagn 1998;44:159e69.
[13] Motarjeme A. Thrombolytic therapy in arterial occlusion and graft thrombosis. Semin Vasc Surg 1989;2:155e78.
[14] Azzalini L, Candilio L, Carlino M, Colombo A. Intracoronary snaring of the retrograde guidewire: how to overcome extreme takeoff angles in
chronic total occlusion percutaneous coronary intervention. Cathet Cardiovasc Interv September 25, 2017. https://doi.org/10.1002/ccd.27324 [Epub
ahead of print].
[15] Topaz O, Topaz A, Polkampally PR. Thrombectomy in acute myocardial infarction. Intervent Cardiol 2009;4:86e91.
[16] Topaz O, Perin EC, Jesse RL, Mohanty PK, Carr ME, Rosenschein U. Power thrombectomy in acute coronary syndromes. Angiology
2003;54:457e68.
[17] Topaz O. The thrombus containing lesion. In: Topol EJ, Tierstein P, editors. Textbook of interventional cardiology. 7th ed. Philadelphia: Elsevier;
2015. p. 439e63.
[18] Topaz O. Editorial. CTO revascularization:obstacles and options in balloon nonpenetrable lesions. Cathet Cardiovasc Interv 2017;90:21e2.
[19] Dahm JB, Topaz O, Woenckhaus C, et al. Laser-facilitated thrombectomy: a new therapeutic option for treatment of thrombus e laden coronary
lesions. Cathet Cardiovasc Interv 2002;56:365e72.
[20] Topaz O, Minisi AJ, Morris C, Mohanty PK, Carr Jr ME. Photoacoustic fibrinolysis: pulsed-wave, mid infrared laser-clot interaction. J Thromb
Thrombolysis 1996;3:209e14.
[21] Topaz O, Minisi AJ, Bernardo NL, McPherson RA, Martin E, Carr SL, Carr Jr ME. Alterations of platelet aggregation kinetics with ultraviolet laser
emission: the “stunned platelet” phenomenon. Thromb Haemost 2001;86:1087e93.
[22] Topaz O. Laser for total occlusion recanalization. In: Waksman R, Saito S, editors. Chronic total occlusions: a guide to recanalization. 2nd ed.
Hoboken, NJ: Blackwell Publishing; 2013. p. 251e6.
[23] Holmes Jr DR, Forrester JS, Litvack F, et al. Chronic total obstructions and short term outcome :the excimer laser angioplasty registry experience.
Mayo Clin Proc 1993;68:5
[24] Dahm JB, Ebersole D, Das T, et al. Prevention of distal embolization and no-reflow in patients with acute myocardial infarction and total occlusion
in the infarct-related vessels. Cathet Cardiovasc Interv 2005;64:67e74.
[25] Lee PH, Lee SW, Yun SC, Ahn JM, Park DW, Kang SJ, et al. Full metal jacket with drug-eluting stents for coronary chronic total occlusion. JACC
Cardiovasc Interv 2017;10:1405e12.
[26] Shammas NW, Dippel EJ, Shammas G, Gayton L, Coiner D, Jerin M. Dethrombosis of the lower extremity arteries using the power -pulse spray
technique in patients with recent onset thrombotic occlusions: results of the DETHRMBOSIS registry. J Endovasc Ther 2008;15:570e9.
[27] Shammas NW. Treatment of subacute and chronic thrombotic occlusions of the lower extremity peripheral arteries: the role of excimer laser. In:
Topaz O, editor. Lasers in cardiovascular interventions. London, UK: Springer; 2016. p. 157e66.
[28] Laird JR, Reiser C, Biamino G, Zeller T. Excimer laser assisted angioplasty for the treatment of Chronic total occlusions that cause critical limb
ischemia such as complex tibial disease can be recanalized successfully as well critical limb ischemia. J Cardiovasc Surg 2004;45:239e45.
[29] Zeller T, Scheinert D. Laser angioplasty for critical limb ischemia. Endovasc Today 2004;2:63e5.
e10.
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[30] Das TS. Percutaneous peripheral revascularization with excimer laser: equipment, technique and results. Lasers Med Sci 2001;16:101e7.
[31] Boccalandro F, Muench A, Sdringola S, Rosales OR. Wireless laser assisted angioplasty of the superficial femoral artery in patients with critical limb
ischemia who have failed conventional percutaneous revascularization. Cathet Cardiovasc Interv 2004;63:7e12.
[32] Bosiers M, Peeters P, Elst FV, et al. Excimer laser assisted angioplasty for critical limb ischemia; results of the LACI Belgium study. Eur J Vasc
Endovasc Surg 2005;29:613e9.
Chapter 22
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Encounters With Thrombus and
Thrombosis in a Major Academic Center:
Cases as “Pictures at an Exhibit ion”
Jurgen Ligthart1, Claire Ren1, Evelyn Regar2and Peter de Jaegere
1
Erasmus University Rotterdam, Rotterdam, The Netherlands;2University Hospital Zurich, Zürich, Switzerland
1
SUMMARY
Thrombus plays a major role in the pathology and physiology of acute coronary ischemic syndromes. This chapter
highlights the diagnosis and management of challenging cases, which illustrates the prevalence and impact of cardiovascular thrombus as encountered through the experience of a major academic center. The benefits and limitations of
imaging modalities such as angiography, intracoronary ultrasound, optical coherence tomography, and echocardiography are reviewed and discussed. Contemporary cardiovascular imaging allows thrombus to be directly visualized for
diagnostic and therapeuti c purposes. The acoustic homogeneity of thrombus allows the achievement o f precise interpretation regarding the composition and age of the targ eted thrombus. Among these tools, the optical coherence
tomographye and ultrasound-based technologies are often superior to the commonly utilized angiography. As illustrated
by multiple cases throughout this chapte r, the incorporation of multiple imaging modalities affords practitioners a
comprehensive assessment of cardiovascular thrombus. This approach enables the tailoring of specific thrombus eradication therapies.
INTRODUCTION
The care and treatment of patients with cardiovascular atherosclerosis involve walking a fine line of protecting the patient
from the sequelae of intracardiac or intravascular thrombi: such thrombi are spontaneous, pathologic in the event of acute
coronary syndrome, or iatrogenic due to intracardiac and vascular interventions. There is also a concurrent need to
reduce the risk of pharmacotherapy-i nduced bleeding caused by antiplatelet therapy with or without adjunct anticoagulant
drugs [1].
The objective of this chapter is to offer the reader a spectrum of clinical situations encountered in a major academic
medical center, in which intracardiac or intracoronary thrombosis resulted from underlying cardiovascular disease or
catheter-based interventions. Similar to Pictures at an Exhibition by the famous Russian composer Mussorgsky, the
chapter is formatted as a promenade in which the reader is invited to look at the pictures in the spirit of the composer,
namely “allegro giust o. ” For that reason, the text has been kept to a minimum so that the pictures speak for themselves.
The content of this chapter is as follows:
1. Intracoronary thrombosis: distinction between acute, subacute, and organized thrombus
2. Intracardiac thrombosis: clinical situations and detection
3. Thrombosis following catheter-based structural heart interventions
Cardiovascular Thrombus. https://doi.org/10.1016/B978-0-12-812615-8.00022-3
Copyright © 2018 Elsevier Inc. All rights reserved.
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INTRACORONARY THROMBUS: DISTINCTION BETWEEN ACUTE, SUBACUTE, AND
ORGANIZED THROMBUS
Intravascular ultrasound (IVUS) and optical coherence tomography are intravascular imaging modalities that create crosssectional images of the coronary artery and associated pathology, such as the presence of thrombi, with higher diagnostic
accuracy than conventional angiography or noninvasive computed tomography imaging [2].
By IVUS, thrombus can be directly visualized, which is often superior to angiography. Thrombus appears as a
sonolucent, irre gular mass. Thrombus recognition can be challenging when there is only limited contrast between the
thrombus and the surrounding blood speckles. Diagnostic accuracy can be improved by assessing a moving image as
opposed to a single still frame. This allows moving blood speckles to be distinguished from stationary thrombi. Alternatively, injection of saline during IVUS image acquisition can augment the contrast and allow for a clear diagnosis.
Moreover, the acoustic homogeneity of a thrombus might allow one to draw conclusions regarding the composition and
age, as an ultrasound image is based upon the differences in acoustic impedance within and between tissues.
The acoustic impedance of a tissue is defined by the product of its density and acoustic velocity (Table 22.1). Sound
waves that travel through a homogeneous tissue will be less reflected, thus creating a darker image, while a sound traveling
through a tissue with a heterogeneous architecture will yield a brighter picture due to a more pronounced difference in
acoustic impedance. Therefore, we speculate that in certain instances IVUS might allow the detection of the various phases
of thrombus formation (Fig. 22.1). One needs to recognize that the limitations of a diagnostic modality (sensitivity,
specificity) necessitate a critical assessment and the formulation of a differential diagnosis. Proper interpretation of the
image must be supported by relevant clinical information and procedures as illustrated in the following cases
(Figs. 22.2e22.12).
Thrombus and Optical Coherence Tomography
Optical coherence tomography (OCT) is a novel invasive imaging method that creates, similar to IVUS, a cross-sectional
image of the artery. However, light at approximately 1400-nm wavelength is used to generate the image and not sound,
which carries major implications. First, the image resolution is about a factor of 10 higher than IVUS, currently in the range
of 15 mm. This is, however, at the expense of a limited penetration depth into the tissue (approximately 1e2 mm). Second,
blood has to be removed from the field of view, as light is scattered by erythrocytes. During OCT imaging, the lumen is
being flushed. This results in a high contrast between the lumen (which appears signal-poor or “black”) and the vessel wall.
Therefore, it is simple to identify additional structures, such as intraluminal or mural thrombi. Thrombi appear as signalrich structures with irregular surface [5].
OCT can distinguish two types of thrombi, namely a red or a white thrombus [6]. Postmortem studies analyzing
thrombi reveal that white thrombus consists mainly of platelets and white blood cells, while red thrombus mainly contains
red blood cells. OCT also has better penetration through white thrombus than through red thrombus (Figs. 22.13 and
22.14).
TABLE 22.1 Density, Sound Velocity and Acoustic Impedance of different media
Sound
Medium Density (kg/m3)
Air 1.20 330 0.0004
Water 1.00 10
Blood 1.03 10
Muscle 1.07 10
Fat 0.93 10
Bone (calcium) 1.91 10
PZT (transducer) 7.3 10
3
3
3
3
3
3
Velocity (m/s)
1480 1.47
1570 1.62
1585 1.67
1450 1.38
4080 7.80
4100 30
Acoustic
Impedance (Mrayl)
PZT, Piezoelectric Ultrasonic Transducercorrecr.
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FIGURE 22.1 Histology of different stages of thrombus. Top: Platelet aggregation that is acoustically inhomogeneous. On intravascular ultrasound
(IVUS) this would appear as “spontaneous contrast” [3]. Middle: A later phase of the process of thrombosis during which the so-called lines of Zahn
develop [4]. They are acoustically more homogeneous than the phase of platelet aggregation. On IVUS this would translate into a darker area. Bottom: The
process of granulation (G) that starts from the vessel wall (W) and results in an acoustically homogeneous area that appears as dark or even black on IVUS.
Er, erythrocyte; F, fibrin; Pl, platelet; R, red blood cell.
FIGURE 22.2 Suspicion of thrombus surrounding an intravascular ultrasound (IVUS) catheter. Acute thrombus (platelet aggregation) on the
IVUS catheter as a result of insufficient heparin and antiplatelet treatment prior to the vessel interrogation. The thrombus appears as an inhomogeneous
area around the catheter with preserved lumen (arrows in the right image).
The difference between postmortem and antemortem thrombi needs to be recognized (Table 22.2), implying that the
composition of the thrombus as seen on OCT may differ from the composition seen during a postmortem exam [7].
INTRACARDIAC THROMBUS: CLINICAL SITUATIONS AND DETECTION
Transesophageal echocardiography is routinely used in the preprocedural screening for detecting the presence of left-atrial
appendage thrombus in candidates for catheter-based procedures such as ablation, septal defect occluding, and MitraClip
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FIGURE 22.3 Deciphering obstructive plaque from spasm. Suspicion of an obstructive plaque (top left, c) with obstruction of the coronary artery (top
left, d). Yet, spasm was suspected, with stasis of blood proximal to the spasm leading to a scattered or inhomogeneous mass mimicking an atherosclerotic
plaque. Arrowhead indicates the proximal border of the spasm, occluding the vessel. The asterisks indicate a sidebranch. After administration of
intracoronary nitroglycerin the spasm was relieved allowing proper interpretation of the images (absence of disease) (right). B, C, and D correspond to b, c,
and d.
(A)
(C)
(B)
(D)
FIGURE 22.4 Iatrogenic thrombosis. A patient with out-of-hospital cardiac arrest underwent coronary angiography. Procedure was started without the
administration of heparin nor antiplatelet therapy because of an international normalized ratio (INR) of 2.5. (A and B) Angiogram and intravascular
ultrasound (IVUS) assessment, respectively, of the left main and proximal left anterior descending artery. (C) Repeat angiogram revealed angiographic
evidence of a large thrombus (arrow). (D) Despite evidence of thrombus, IVUS was repeated, revealing a large mass with a scattered appearance that is
typical of an acute thrombus (platelet aggregation and, therefore, acoustically inhomogeneous). Arrowheads indicate this thrombus in the ostial left
anterior descending artery and the ostial circumflex artery (cx). The thrombus was successfully extracted with an aspiration catheter.
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