JACC Vol. 25, No. 7 1681 June 1995:1681-4

INTERVENTIONAL CARDIOLOGY

Coronary Angioscopy of Abrupt Occlusion After Angioplasty C H R I S T O P H E R J. W H I T E , MD, FACC, S T E P H E N R. R A M E E , MD, FACC,*

T Y R O N E J. COLLINS, MD, FACC,* S U R E S H P. JAIN, MD,* A L V A R O E S C O B A R , MD*

Clydebank, Scotland, United Kingdom and New Orleans, Louisiana

Objectives. This study used angioscopy to determine the specific cause of vessel occlusion after percutaneous transluminal coro- nary angioplasty and compared the angiographic and angioscopic lesion morphologies in this setting.

Background. Occlusion of a dilated coronary artery is the major • cause of morbidity and mortality after coronary angioplasty.

Attempts to reopen occluded vessels are either empirically guided or directed by angiography, which has inherent limitations. Angioscopy, the in vivo direct visualization of the endovascular surface, is potentially a more accurate means of identifying the cause of vessel occlusion after angioplasty.

Methods. Percutaneous coronary angioscopy was performed in 17 patients (17 vessels) after angiographic confirmation of post- angioplasty vessel occlusion.

Results. Angioscopy demonstrated the primary cause of the postangioplasty occlusion to be dissection in 14 patients (82%)

and intracoronary thrombi in 3 (18%). Compared with angios- copy, angiography was significantly less accurate in identifying the specific cause of the occlusion and correctly identified the cause of vessel occlusion in only 5 (29%) of 17 patients (p < 0.001), including 4 (29%) of 14 deep dissections and 1 (33%) of 3 occlusive thrombi.

Conclusions. Angioseopy specifically identified the cause of occlusion in every patient, with coronary dissection the predomi- nant cause of abrupt occlusion after coronary angioplasty. How- ever, angiography was unable to identify a specific cause for vessel occlusion in the majority of our patients. Angioscopy may there- fore prove useful in selecting specific treatment strategies for patients with abrupt occlusion after angioplasty, such as stent placement, atherectomy, repeat dilation or thrombolysis.

(J Am CoU Cardio11995;25:1681-4)

Abrupt occlusion, the sudden closure of a coronary artery after attempted angioplasty, is the major cause of in-hospital mor- bidity and mortality associated with percutaneous transluminal coronary angioplasty (1-5). Prompt restoration of blood flow is necessary to avoid myocardial infarction. Available therapies include repeat (long) balloon dilation, intracoronary thrombol- ysis, directional atherectomy, stent implantation, emergency coronary bypass surgery and administration of intracoronary nitroglycerin. Treatment of abrupt occlusion may either be empirically determined or guided by the angiographic appear- ance of the lesion. However, angiography has inherent limita- tions for specifically identifying intraluminal morphologies, such as intracoronary thrombus and plaque rupture (6-8). Angiography has also demonstrated a lack of precision in determining the presence of intracoronary thrombus or dissec- tion in patients undergoing coronary angioplasty (9-11).

Coronary angioscopy, the direct visualization of the endolu- minal surface, is more sensitive than angiography for the

From the Department of Invasive Cardiology, HCI International Medical Center, Clydebank, Scotland, United Kingdom; and *Department of Internal Medicine, Section of Cardiology, Ochsner Clinic and Alton Ochsner Medical Foundation, New Orleans, Louisiana.

Manuscript received January 3, 1994; revised manuscript received January 26, 1995, accepted February 14, 1995.

Address for correspondence: Dr. Christopher J. White, Director, Invasive Cardiology, HCI International Medical Center, Ctydebank, Scotland G81 4HX, United Kingdom.

identification of complex atherosclerotic plaque and intracoro- nary thrombi in native coronary arteries and bypass grafts during angioplasty (12-14). Angioscopy also provides specific information regarding intraluminal morphology, such as the presence of tissue fragments or "flaps" obstructing the lumen of the vessel (15).

The purpose of this study was to use angioscopy to deter- mine the specific cause of vessel occlusion after angioplasty and to compare the angiographic and angioscopic lesion morphologies in this setting.

M e t h o d s

Patients. The 17 patients included in this study (14 men, 3 women; mean age 6.14 years, range 50 to 80) had clinical (chest pain and electrocardiographic changes) and angiographic evi- dence of a critical reduction in coronary flow after successful angioplasty but do not represent a consecutive series of patients with abrupt occlusion. Patients were not considered candidates for angioscopy if the lesion to be imaged was judged too proximal in the coronary artery to allow room for inflation of the occlusion balloon (<2 cm from the ostium of the vessel) or if they were in hemodynamically unstable condition (systolic pressure <100 mm Hg).

Abrupt occlusion, defined as the sudden occurrence of coronary isehemia within 4 h of coronary angioplasty, was documented with angiographic evidence of total or subtotal

©1995 by the American College of Cardiology 0735-1097/95/$9.50 0735-1097(95)00112-H

1682 WHITE ET AL. JACC Vol. 25, No. 7 ANGIOSCOPY OF ABRUPT OCCLUSION June 1995:1681-4

Figure 1. Angioscope (Baxter Imagecath) with occlusion balloon inflated. Bottom, the image bundle has been extended in monorail fashion over the angioplasty guide wire.

occlusion of the dilated vessel in all 17 patients, 11 of whom had abrupt occlusion before, and 6 after, leaving the catheter- ization laboratory. Written informed consent was obtained from each patient, and the protocol was approved by the hospital Institutional Review Board.

Two of 17 patients had stable angina refractory to medical therapy. Fifteen patients had unstable angina: four had recur- rent angina after a myocardial infarction, five rest angina and six crescendo angina. Abrupt occlusion after angioplasty oc- curred in 2 saphenous vein grafts and 15 native coronary arteries.

Angioseopy. Percutaneous coronary angioscopy was per- formed with a 4.5 F rapid exchange angioscope (Imagecath, Baxter Healthcare), shown in Figure 1. The angioscopic system consisted of an imaging catheter, light source, color television camera and monitor and a 0.75-in. videotape recorder. The angioscope has an image bundle containing 3,000 optical fibers within the central lumen of the angioscope. The scope is composed of two elements, both guided in a monorail fashion by a single 0.014-in. angioplasty guide wire. The inner element (image bundle) is concentrically contained within the outer catheter and consists of 3,000 optical fibers with a microlens at its distal tip. This image bundle may be independently ad- vanced - 6 cm from the tip of the outer delivery catheter. A compliant occlusion balloon is located at the distal tip of the outer delivery catheter. The occlusion balloon may be hand inflated with a 1.0-ml syringe filled with 1:1 mix of saline solution and radiographic contrast agent to interrupt antero- grade coronary blood flow. An optically clear solution can then be infused through the lumen of the outer catheter and distal to the occlusion balloon to create a blood-free field of view in the segment of the coronary artery to be examined.

The coronary artery of interest was cannulated with a conventional 8F angioplasty guiding catheter, and 10,000 U of heparin were administered. After the target lesion had been crossed with the angioplasty guide wire, the angioscope was advanced into the proximal portion of the coronary artery. Warmed saline solution was infused through the outer catheter at a rate of 0.5 to 1.0 ml/s, and the occlusion balloon was gently and gradually hand inflated as the live angioscope image was viewed on the television monitor. After the angioscopic field of view was flushed clear of blood, inflation of the occlusion balloon was held constant, and the image bundle was advanced over the guide wire to examine the surface of the vessel. Each image acquisition took from 15 to 45 s, after which the

occlusion balloon was deflated to allow anterograde blood flow to resume distal to the angioscope.

Preparation of the angioscope entails connecting three umbilicals from the image bundle, light source and saline infusion, as well as balancing color and focusing the scope, which may take 3 to 5 rain. Very little time (<1 min) is needed to exchange the angioscope for a balloon dilation catheter because of its rapid exchange design. Intravascular images can be obtained within minutes of introducing the scope into the vessel.

Image analysis. Angioscopic images were recorded on videotape for later review and comparison with the cineangio- graphic film images. Angioscopic images were interpreted without knowledge of the patient's clinical or angiographic data. Dissection was defined as a tear or disruption of the surface of the plaque or vessel wall. Superficial dissections (nonocclusive) consisted of shallow tears in the vessel surface, without exposure of the deeper muscle layers of the media, and dissections appeared as flimsy white surface disruptions that were not massive enough to embarrass lumen patency. Occlu- sive, deep dissections were identified as bulky tissue fragments within the vessel lumen large enough to cause obstruction of flow. Intracoronary thrombi were classified as either red patches lying flat against the vessel wall (nonoeelusive thrombus) or as globular, intraluminal red masses (occlusive thrombus),

Angiographic images were interpreted in blinded manner, without knowledge of the patient's clinical or angiographic data. Dissection was defined as contrast staining of the vessel wall, a curvilinear filling defect parallel to the vessel lumen or a spiral defect partially occluding the vessel lumen. Anglo- graphic thrombus was defined as discrete or mobile filling defects at the site of the occlusion. Lesions not meeting specific criteria for a thrombus or dissection were labeled indetermi- nate.

Statistical methods. The Fisher exact test was used to compare angioscopic versus angiographic results in the detec- tion of both dissections and thrombus and in the determination of the underlying causes of abrupt occlusion after balloon angioplasty. Angioscopy was assumed to be the reference standard, and p _< 0.05 was accepted as statistically significant.

Resul t s

Angioscopy versus angiography. Compared with direct vi- sualization (angioscopy) of the lesion, considered the refer- ence standard in the present study, angiography correctly identified the cause of abrupt occlusion in only 5 (29%) of 17 patients (p < 0.001) (Table 1). Diagnostic angioscopic images were obtained in each patient without complications attribut- able to the angioscopy procedure. Dissections (nonocclusive and occlusive) were visualized by angioscopy in all 17 patients (100%) whereas angiography identified dissections in only 4 (24%) (p = 0.0005) (Fig. 2). Occlusive dissection with bulky tissue fragments obstructing the lumen of the vessel was the primary cause of the occlusion in 14 patients (82%). Incidental superficial dissections were identified by angioscopy in the

JACC Vol. 25, No. 7 WHITE ET A L 1683 June 1995:1681-4 ANGIOSCOPY OF ABRUPT OCCLUSION

Table 1. Angioscopic Versus Angiographic Identification of Cause of Occlusion

Thrombus Dissection Indeterminate

Angioscopy 3 14 0 Angiography 2* 4 11

*One angiographic thrombuswas a false positive finding.

remaining three patients. Angiography detected none of the 3 superficial dissections and correctly identified only 4 (29%) of 14 occlusive dissections visualized with the angioscope (p = 0.003).

Intracoronary red thrombi were identified by angioscopy in 13 (77%) of 17 vessels (Fig. 3). Nonobstructive thrombi were present in 10 vessels (59%) and in each case were associated

• with deep dissections. In three vessels (18%), occlusive intralu- minal thrombi were seen. In each of these thrombotic occlu- sions, superficial plaque disruptions (nonocclusive dissections) were also observed but did not contribute to the lumen obstruction. All three patients with occlusive intraluminal thrombi had unstable angina (two patients with postmyocardial infarction angina and one with a crescendo pattern of angina).

Two vessels were identified by angiography as containing intraluminal (occlusive) thrombi. In one case, angiography correctly identified one of the three vessels seen with angios- copy to have occlusive intraluminal thrombi. In the second case, angiography mistakenly identified thrombus in a vessel in which angioscopy revealed a deep dissection and an obstruc- tive tissue flap. None of the nonocclusive thrombi (n = 10) seen with angioscopy were detected by angiography (p < 0.0001).

Procedural outcomes• The angioscopic findings guided our therapeutic strategy. The three patients with occlusive thrombi were treated with a selective infusion of 250,000 U of intra- coronary urokinase (Abbokinase, Abbot Laboratories) over 30 rain. Urokinase was used alone in one of these three patients (Fig. 4) and as an adjunct to repeat balloon dilation in

Figure 2. Angiogram of abrupt occlusion (arrow). Angioscopy reveals the lumen to be obstructed with a tissue flap secondary to dissection. W = guide wire within the vessel lumen.

Figure 3• Angiogram of abrupt occlusion after angioplasty. Angios- copy reveals intraluminal red thrombus (T) occluding the lumen. W = guide wire within the vessel lumen.

the other two. Repeat balloon dilation successfully salvaged the occluded vessels without infarction in these two patients. However, vessel patency could not be sustained in one of these patients, and he underwent emergency bypass surgery with a perfusion balloon across the lesion to maintain flow.

Of the 14 patients with occlusive dissections, vessel salvage with long balloon inflations was unsuccessful in 2, and they underwent emergency coronary bypass surgery. One of these patients had a non-Q wave infarction. Of the remaining 12 patients with tissue flaps (occlusive dissections) obstructing the lumen, repeat balloon dilation was successful in 8, recanaliza- tion with directional coronary atherectomy and repeat balloon inflation was successful in 3, and 1 underwent coronary stent- ing to restore patency. Two of the 12 patients with successfully reopened vessels developed a Q wave infarction.

Complications• There were no complications related to the angioscopic procedure. The occlusion balloon was inflated proximal to the dilated lesion, and the abrupt occlusions occurred at the site of the dilated lesion in every case. There were no deaths, strokes, sustained ventricular arrhythmias or episodes of hemodynamic collapse in any of the patients. Three patients required emergency coronary bypass surgery

Figure 4. Angioscopic images showing occlusive intraluminal throm- bus (T) (left) before treatment with 250,000 U of intracoronary urokinase and (right) dissolution of the thrombus after therapy. L = vessel lumen.

1684 WHITE ET AL. JACC Vol. 25, No. 7 ANGIOSCOPY OF ABRUPT OCCLUSION June 1995:1681-4

because of inability to maintain patency of the occluded artery. Three patients (18%) had a myocardial infarction (one non-Q wave and two Q wave infarctions). Both Q wave infarctions occurred in patients with abrupt occlusion occurring outside the catheterization laboratory, which unavoidably delayed at- tempts at reopening the vessel.

Discuss ion We demonstrated the safety and feasibility of performing

diagnostic coronary angioscopy in patients with abrupt occlu- sion after coronary angioplasty. The endovascular morphology that we observed in these patients clearly demonstrated the primary cause of the vascular obstruction. Although the ma- jority of the patients (88%) had unstable angina, a condition that has been associated with a high incidence of intracoronary thrombi (7,8), the majority of occlusions after angioplasty were due to dissection and obstructive tissue flaps, not thrombi.

As has been demonstrated in elective comparative studies (6-10), angioscopy was superior to angiography for identifying specific lesion morphologies, such as intracoronary dissection and thrombus. Additionally, we were able to determine a primary cause of the abrupt occlusion with the angioscope when both thrombi and dissections were present. Angioscopic information was used in these patients to select specific treatment modalities directed at the underlying cause of the failed angioplasty attempt (i.e., thrombolytic therapy for thrombus and repeat balloon dilation, directional atherectomy or stent placement for occlusive dissections).

The present study was not a randomized one; therefore, no statement can be made regarding improved outcome in our patients with therapy guided by angioscopic information. How- ever, we believe that specific information regarding the cause of the occlusion allows the operator to more efficiently select an appropriate treatment strategy. This knowledge, if it can be gained rapidly and safely, should expedite the reestablishment of coronary flow and avoid inappropriate (thrombolysis for tissue obstruction ) or unattractive (stents in thrombus-filled arteries) therapies.

The disadvantages of angioscopy, such as the additional procedure time, potential for angioscope-related complica- tions and additional cost, will need to be balanced against the clinical benefits. In our experience, diagnostic images can be obtained rapidly, and complications due to angioscopy, such as dissection secondary to overinflation of the occlusion balloon, are extremely rare. The additional cost of the device will need to be evaluated with regard to the use of multiple therapeutic devices during empirically or angiographically guided salvage angioplasty attempts and with regard to its potential to mini- mize complications by more rapidly and effectively reestablish- ing coronary patency, and thus avoiding emergency coronary bypass surgery.

Summary. We demonstrated the feasibility of performing diagnostic angioscopy in the setting of abrupt occlusion after

coronary angioplasty. Angioscopy allows the operator to spe- cifically identify the cause of the obstruction reliably and quickly and is superior to angiography. The primary cause of abrupt occlusion in our patients with unstable angina was, surprisingly, dissection with lumen obstruction secondary to tissue flaps. Whether the lesion-specific information provided by angioscopy will both be cost-effective and result in improved clinical outcomes will require a comparative trial.

We express our appreciation to Angela Lorio, BA for editorial assistance and to James O'Meara, BSM for technical assistance in reproducing the angioscopic images.

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