Thromboembolic complications of coronary angioplasty

In vivo distribution of particulate matter from coated angioplasty balloon catheters

Most catheter-based vascular medical devices today have hydrophilic lubricious coatings. This study was designed to perform a territory-based downstream analysis of end organs subsequent to angioplasty with coated balloon catheters to better understand the potential in vivo physiological consequence of coating wear materials. Coronary angioplasty was performed on swine using balloon catheters modified with two polyvinylpyrrolidone (PVP)-based coatings of similar lubricity, but different levels of particulates (5-fold) when tested in a tortuous path model. Myocardial tissues examined 28 days post-angioplasty revealed no visible particulates in the animals treated with the lower particulate catheters while 3 of 40 sections from higher particulate catheters contained amorphous foreign material, and 1 of 40 sections from tissue treated with uncoated catheters had amorphous foreign material. Non-target organs and downstream muscle revealed no particulates for any of the treatments. Histological analysis showed that the overall number of vessels with embolic foreign material was low and evidence of myocyte necrosis was rare with either of the coatings investigated in this study.

Prediction of distal embolization during percutaneous coronary intervention for unstable plaques with grayscale and integrated backscatter intravascular ultrasound

OBJECTIVES

We performed microscopic examination of the debris collected by a distal protection device and investigated the usefulness of grayscale and integrated backscatter intravascular ultrasound (IB-IVUS) for the prediction of distal embolization during percutaneous coronary intervention (PCI) in cases of unstable angina.

BACKGROUND

The prediction of distal embolization during PCI has not been studied in depth because assessment of distal embolization is difficult.

METHODS

We prospectively studied 39 consecutive patients with unstable angina who underwent PCI with a filter distal protection device. The preprocedural plaque volume at target lesions was measured with grayscale IVUS and plaque characteristics were assessed with IB-IVUS. We performed microscopic examination of the particles collected by the distal protection device.

RESULTS

There was a significant correlation between the plaque volume and the number of the collected particles >100 μm in diameter (r = 0.48, P = 0.0034). Filter no-reflow (FNR) phenomenon was found in nine patients. The plaque volume was significantly greater (355 ± 133 mm(3) vs. 199 ± 90 mm(3) , P = 0.0004), and the lipid ratio was significantly higher (29.3 ± 4.3% vs. 26.1 ± 4.3 P = 0.045) in the FNR group compared with the non-FNR group. Multivariate logistic regression analysis showed that the plaque volume was an independent predictor of FNR phenomenon.

CONCLUSIONS

Although tissue characterization of IB-IVUS may provide additional information for distal embolization, plaque volume is the only significant predictor of distal embolization during PCI.

Distal protection device protects microvascular integrity during primary percutaneous intervention in acute myocardial infarction: A prospective, randomized, multicenter trial

BACKGROUND

Distal protection during primary angioplasty in acute myocardial infarction (AMI) is the subject of recent controversy. The present study was designed to determine whether the distal embolic protection preserves myocardial microvascular integrity and improves clinical outcomes in patients with AMI.

METHODS

A total of 116 AMI patients presenting within 12 h of onset of symptoms were enrolled at 7 angioplasty centers. They were randomly assigned to either primary angioplasty with distal protection group (DP; n=60) or angioplasty alone group (Controls; n=56).

RESULTS

After primary angioplasty, achievement of final Thrombolysis In Myocardial Infarction (TIMI) grade 3 and TIMI Myocardial Perfusion (TMP) grade 3 were more frequent in the DP group than in the control group [58/60 (96%) vs. 43/56 (81%), p=0.016; and 39/60 (65%) vs. 20/56 (38%), p=0.001, respectively]. After primary angioplasty, the baseline and hyperemic averaged peak velocities were significantly higher (23.2+/-11.5 vs. 18.0+/-6.9 cm/s, p=0.029; and 39.2+/-16.7 vs. 30.6+/-10.8 cm/s, p=0.014, respectively) and the baseline and hyperemic microvascular resistance indices were significantly lower (4.18+/-2.22 vs. 5.34+/-2.25 mm Hg cm(-1) s, p=0.036; and 2.38+/-1.39 vs. 3.11+/-1.32 mm Hg cm(-1) s, p=0.030, respectively) in the DP group. Patients in the DP group showed more favorable phasic coronary flow pattern in diastolic deceleration time (679+/-262 vs. 519+/-289 ms, p=0.035; and 751+/-246 vs. 616+/-269 ms, p=0.035, respectively). Major adverse cardiac events at 6 months occurred with similar frequency in both groups (8.7% vs. 11.1%, p=0.400).

CONCLUSIONS

Distal protection device effectively preserves microvascular integrity during primary angioplasty in AMI. Distal protection, however, did not improve clinical outcomes.

Thrombosuction utilizing an export aspiration catheter during primary percutaneous coronary intervention in acute myocardial infarction

PURPOSE

Effective myocardial reperfusion after primary PCI for an AMI in lesions with a thrombus is limited by distal embolization and the slow/no reflow phenomenon. We evaluated the efficacy of a thrombus reduction technique using an export aspiration catheter for thrombosuction during primary PCI.

MATERIALS AND METHODS

We analyzed 62 patients with AMIs who underwent primary PCI and had a thrombi burden during thrombosuction using an EAC (EAC group; n=31) or without thrombosuction (control group; n=31).

RESULTS

Thrombosuction with an EAC was performed safely in all the patients in EAC group without any complications. After the PCI, restoration to a TIMI flow grade 3 was significantly more frequent in the EAC group (26/31 vs. 20/31, p < 0.05). However, the TIMI perfusion grade did not differ between the two groups. Further, the corrected TIMI frame counts were lower in the EAC group (23.9 +/- 15.1 vs. 34.8 +/- 22.5, p < 0.05). Although there was no statistical significance, a greater incidence of distal embolization was observed in the control group (16.1%, 5/31) as compared to the EAC group (0/31) (p= 0.056). However, the incidence of major adverse cardiac events at 1 and 6 months did not differ between the two groups.

CONCLUSION

For AMIs, thrombosuction with an EAC before or during PCI is a safe and potentially effective method for restoration of the coronary flow.

Thrombus aspiration before primary angioplasty improves myocardial reperfusion in acute myocardial infarction: the DEAR-MI (Dethrombosis to Enhance Acute Reperfusion in Myocardial Infarction) study

OBJECTIVES

This study sought to test the hypothesis that thrombus removal, with a new manual thrombus-aspirating device, before primary percutaneous coronary intervention (PPCI) may improve myocardial reperfusion compared with standard PPCI in patients with ST-segment elevation acute myocardial infarction (STEMI).

BACKGROUND

In STEMI patients, PPCI may cause thrombus dislodgment and impaired microcirculatory reperfusion. Controversial results have been reported with different systems of distal protection or thrombus removal.

METHODS

One-hundred forty-eight consecutive STEMI patients, admitted within 12 h of symptom onset and scheduled for PPCI, were randomly assigned to PPCI (group 1) or manual thrombus aspiration before standard PPCI (group 2). Patients with cardiogenic shock, previous infarction, or thrombolytic therapy were excluded. Primary end points were complete (>70%) ST-segment resolution (STR) and myocardial blush grade (MBG) 3.

RESULTS

Baseline clinical and angiographic characteristics were similar in the 2 groups. Comparing groups 1 and 2: complete STR 50% versus 68% (p < 0.05); MBG-3 44% versus 88% (p < 0.0001); coronary Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 78% versus 89% (p = NS); corrected TIMI frame count 21.5 +/- 12 versus 17.3 +/- 6 (p < 0.01); no reflow 15% versus 3% (p < 0.05); angiographic embolization 19% versus 5% (p < 0.05); direct stenting 24% versus 70% (p < 0.0001); and peak creatine kinase-mass band fraction 910 +/- 128 mug/l versus 790 +/- 132 mug/l (p < 0001). In-hospital clinical events were similar in the 2 groups. After adjusting for confounding factors, multivariate analysis showed thrombus aspiration to be an independent predictor of complete STR and MBG-3.

CONCLUSIONS

Manual thrombus aspiration before PPCI leads to better myocardial reperfusion and is associated with lower creatine kinase mass band fraction release, lower risk of distal embolization, and no reflow compared with standard PPCI. (Thrombus Aspiration Before Standard Primary Angioplasty Improves Myocardial Reperfusion in Acute Myocardial Infarction; http://clinicaltrials.gov/ct/show/NCT00257153).

Distal protection of bifurcating vessels: a novel approach

Distal protection devices protect only a single distal vessel. We describe a novel technique to protect both branches following a thrombus-containing bifurcation lesion. The combination of an occlusive balloon and an arterial filter system provides an attractive solution to the challenging environment of a lesion at high risk for distal embolization supplying more than a single major branch.

Distal protection in native coronary arteries during primary angioplasty in acute myocardial infarction: Single-center experience

Distal embolization of plaque or thrombotic debris is one of the mechanisms involved in the ischemia/reperfusion injury during primary percutaneous intervention for acute occlusion of a native coronary artery. We tested the clinical application of maximal antiplatelet therapy with abciximab combined with one of two different systems of mechanical distal protection: balloon occlusion and aspiration (PercuSurge) in 24 cases and a distal filter (FilterWire Ex) in 10 cases. Feasibility, technical limitations, and pitfalls are described.

Predicting angiographic distal embolization following percutaneous coronary intervention in patients with acute myocardial infarction

The aim of this study was to investigate the relation between lesion morphology identified by intravascular ultrasound (IVUS) before intervention and angiographic distal embolization after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). PCI for AMI has already been established as beneficial therapy, although some complications remain unresolved. Distal embolization is 1 of the important complications of PCI. Recently, some new devices have been developed for the prevention of distal embolization. However, few studies exist that look into the relation between lesion morphology and distal embolization. IVUS was performed safely in 140 consecutive patients with AMI before coronary intervention. No patient received thrombolytic therapy. From the incidence of angiographic distal embolization, patients were divided into 2 groups--an embolization group and a nonembolization group--and clinical background, IVUS, and angiographic information were evaluated. Distal embolization was observed in 12 patients (9%). Peak creatine kinase levels (3,877 +/- 2,285 vs 2,293 +/- 1,792 IU/L, p <0.05) and the incidence of angiographic thrombus (25% vs 5%, p <0.05) and intracoronary mobile mass detected by IVUS (75% vs 16%, p <0.001) were higher for patients in the embolization group. From the multivariate logistic regression analysis, only an intracoronary mobile mass detected by IVUS emerged as a predictor of distal embolization (odds ratio 53, 95% confidence interval 2.7 to 1,040, p <0.01). Patients with an intracoronary mobile mass detected by IVUS are prone to distal embolization after PCI and larger infarction. IVUS imaging before PCI may be useful for determining which patients need a distal protection device.

Prevention of distal embolization during coronary angioplasty in saphenous vein grafts and native vessels using porous filter protection

BACKGROUND

Although distal embolization and the "no-reflow" phenomenon are well described in saphenous vein graft (SVG) interventions, the frequency, magnitude, and characterization of embolized debris have not been evaluated in routine coronary interventions. A unique embolus protection device described herein provides a means of containing and retrieving plaque material dislodged during percutaneous coronary interventions. This report details the first clinical experience of the effectiveness and safety of an emboli protection system in 11 SVG lesions and 15 native coronary artery lesions.

METHODS AND RESULTS

The AngioGuard Emboli Capture Guidewire (Cordis) consists of a PTCA wire with an expandable filter at the distal tip. The porous membrane permits normal distal blood flow, while trapping potential emboli by filtration. After crossing the lesion, the filter is expanded, and routine angioplasty is performed over the same wire. Emboli retrieval is achieved by collapsing the filter and retracting the emboli capture wire (ECW). In 26 patients, standard angioplasty was performed over the ECW; 20 of these 26 patients received a stent. Collected debris was sent for histopathological analysis. Plaque debris was retrieved after native coronary and SVG interventions in all cases. The ECW was positioned and retrieved without complications. No major adverse events occurred. Myocardial infarctions and no-reflow were not observed.

CONCLUSIONS

The embolization of plaque fragments frequently occurs during coronary and SVG intervention. Distal embolization leading to microvascular obstruction and no-reflow could be successfully minimized by using the ECW.

Adjunctive thrombus aspiration and mechanical protection from distal embolization in primary percutaneous intervention for acute myocardial infarction

Primary percutaneous intervention for acute occlusion of a native coronary artery may be complicated by distal embolization of plaque or thrombotic debris, with infarct extension. We tested the clinical application of a new therapeutic strategy combining maximal antiplatelet therapy, with glycoprotein IIb/IIIa inhibition, and adjunctive mechanical protection from distal embolization and direct aspiration of thrombus with a new balloon and catheter system (PercuSurgetrade mark). Successful aspiration of thrombus could be obtained in 7 out of 8 attempted procedures, with inability to negotiate the angulated take-off of the circumflex coronary artery in one patient. The current mechanical characteristics of the device, primarily developed for use in larger saphenous vein grafts, and certain caveats and limitations are discussed. New dedicated systems should be available in the near future for the native coronary circulation. Excellent immediate angiographic results were obtained in all treated patients, without evidence of loss of distal branches and no intraprocedural complications.

Potential embolization by atherosclerotic debris dislodged from aortic wall during cardiac catheterization:: histological and clinical findings in 7,621 patients

Embolic events during cardiac catheterization have been attributed to atherosclerotic aortic debris dislodged by catheter manipulation. We evaluated the frequency and the histologic morphology of atherothrombotic material retrieved during placement of coronary catheters in patients undergoing diagnostic or interventional cardiac procedures. Over a 4-year period, macroscopically visible aortic debris from coronary catheters, if present after advancement to the ascending aorta, was obtained for histologic examination. In 41 of 7,621 patients (0.54%), visible atherothrombotic material was present in the backflow of catheters. Debris occurred most frequently with 8 Fr guiding catheters (98%). Histologic examination showed foam cells, cholesterol crystals, and amorphic lipoid substance as markers of atheromatous material from atherosclerotic plaques in 38/41 patients (93%) with former plaque hemorrhage in 55% of them. In three patients, fresh thrombus material was observed (7%). None of these patients showed in-hospital ischemic complications. Although visible atheromatous material is a rare phenomenon in cardiac catheterization, an increased risk of scraping debris is associated with large-lumen guiding catheters. In order to avoid vascular embolization, the use of smaller guiding catheters and sufficient free backflow of catheters after advancement are recommended.

Impact of embolization during coronary artery bypass grafting on outcome and length of stay

BACKGROUND

Transcranial Doppler ultrasonography detects emboli in most patients during coronary artery bypass grafting. However, the significance of these emboli has not yet been established.

METHODS

We monitored 82 patients during coronary artery bypass grafting with this technique and related the numbers of emboli to the outcomes and length of hospital stay.

RESULTS

We detected cerebral emboli in all patients. Patients with stroke (n = 4; 4.9%) had a mean of 449 emboli, as compared with 169 emboli in patients without stroke (n = 78) (p = 0.005). Patients with major cardiac complications (n = 7) had a mean of 392 emboli, as compared with 163 in patients without such complications (n = 75) (p = 0.003). The mean hospital stay of survivors was 8.6 days in patients with fewer than 100 emboli (n = 40), 13.5 days in patients with 101 to 300 emboli (n = 23), 16.3 days in those with 301 to 500 emboli (n = 16), and 55.8 days in patients with more than 500 emboli (n = 6) (p = 0.0007). This relation was unchanged when patients with complications were excluded. The correlation between embolization and outcome was independent of the extent of aortic atheroma or age.

CONCLUSIONS

Emboli detected during coronary artery bypass grafting are significantly related to major cardiac and neurologic complications and affect length of stay in all patients, even in the absence of such specific complications.

Coronary artery and saphenous vein graft remodeling: a review of histologic findings after various interventional procedures--Part IV

Catheter balloon angioplasty is a well accepted form of nonsurgical treatment of acutely and chronically obstructed coronary artery vessels. It is also the centerpiece for various new intervention techniques. Their morphologic effects on the site of obstruction has been termed "remodeling." Part IV of this six-part series focuses on morphologic correlates of coronary angiographic patterns of remodeling after balloon angioplasty and discusses effects of angioplasty on adjacent, nondilated vessels.

Early and late quantitative angiographic results of vein graft lesions treated by excimer laser with adjunctive balloon angioplasty

BACKGROUND

Percutaneous excimer laser coronary angioplasty (PELCA) has been approved for treatment of diseased saphenous vein bypass grafts. However, detailed and complete quantitative angiographic analysis of immediate procedural and late follow-up results has not been performed.

METHODS AND RESULTS

PELCA using the CVX-300 excimer laser system was performed in 125 bypass lesions (mean graft age, 96 +/- 53 months; range, 2 to 240 months) in 106 consecutive patients at eight centers. Quantitative analyses of the procedural and follow-up angiograms were done with the Cardiac Measurement System. Stand-alone PELCA was done in 21 lesions (17%). Lesions were located at the ostium (20%), body (67%), or distal anastomosis (13%). The graft reference diameter was 3.26 +/- 0.79 mm (mean +/- SD). Minimal lumen diameter increased from 1.09 +/- 0.52 mm before treatment to 1.61 +/- 0.69 mm after laser and 2.18 +/- 0.63 mm after adjunctive balloon dilation (P < .001) but had declined at follow-up to 1.40 +/- 1.17 mm. Dissections were evident in 45% of lesions after laser treatment (types A and B, 27%; types C through F, 18%), including 7% occlusions. Angiographic success (< or = 50% diameter stenosis [% DS]) was 54% after laser and 91% after adjunctive PTCA, with an overall clinical success rate of 89%. In-hospital complications were death, 0.9%; myocardial infarction (Q-wave and non-Q-wave), 4.5%; and bypass surgery, 0.9%. Independent predictors of % DS after laser were reference diameter, lesion length, and minimal lumen diameter before laser. At angiographic follow-up in 83% of eligible patients, the restenosis rate per lesion (DS > 50%) was 52%, including 23 occlusions (24%). The only independent predictor of increased % DS at follow-up was lesion symmetry. Logistic regression indicated that smaller reference diameter was an independent predictor of late occlusion. Overall 1-year mortality was 8.6%. Actuarial event-free survival (freedom from death, myocardial infarction, bypass surgery, or target vessel percutaneous transluminal coronary angioplasty) was 48.2% at 1 year.

CONCLUSIONS

Excimer laser angioplasty with adjunctive balloon angioplasty can be safely and successfully performed in diseased, old saphenous vein bypass graft lesions considered at high risk for reintervention. The extent of laser ablation remains limited by the diameter and effectiveness of the catheters. Late restenosis and, in particular, total occlusion mitigate the early benefits of the procedure. Other approaches such as the routine use of additional anticoagulation (eg, warfarin) should be considered to reduce the risk of late occlusions and restenosis after laser angioplasty of bypass grafts.

Angioscopic versus angiographic detection of thrombus during coronary interventional procedures

The purpose of this study was to compare angiography and angioscopy for the detection of thrombus during coronary interventional procedures. The diagnosis of coronary thrombus has important clinical implications. Angioscopy can directly visualize the coronary luminal surface and may be more accurate than angiography in the diagnosis of thrombus. Angiography and angioscopy were sequentially performed in 75 patients undergoing a variety of interventional cardiology procedures during 117 distinct procedural time points. The angiographic presence of thrombus was defined as a noncalcified filling defect outlined on at least 3 sides by contrast media. The angioscopic presence of thrombus was defined as red material protruding into the lumen (intraluminal thrombus) or adherent to the luminal wall (mural thrombus) that persisted despite flushing. Thrombus was detected on 14 occasions (12.0%) by angiography compared with 48 (41.0%) by angioscopy (p < 0.05). In 4 of the 14 episodes (28.6%) of angiographic filling defects, angioscopy found no evidence of thrombus and provided an alternative explanation for the angiographic filling defect. When angioscopy was used as a reference standard, the sensitivity of thrombus detection by angiography was 20.8%, with a specificity of 94.2% and a predictive value of 71.4%. The sensitivity of angiography for the detection of intraluminal (protruding into the lumen) thrombus was 100% compared with only 10% for mural (adherent to the luminal wall) thrombus (p < 0.05). Angioscopy was significantly more accurate than angiography for detecting coronary thrombus and may be considered an improved reference standard for this diagnosis.

Distal embolization is common after directional atherectomy in coronary arteries and saphenous vein grafts

Coronary embolization is a complication of coronary intervention procedures. The incidence, predictors, and clinical significance of this phenomenon during directional atherectomy were examined in 111 consecutive patients who underwent directional atherectomy to 120 lesions. Distal embolization occurred in 31 (28%) of the patients. It was noted mainly in the saphenous vein graft group of patients (12 [48%] of 25) versus the native coronary group (19 [22% of 86]; p = 0.01). Clinical predictors were age and de novo lesions. Morphologic predictors were larger artery size, larger postprocedure minimal luminal diameter, calcific lesions, and type C lesions. The only difference in clinical outcome was a longer hospitalization in the distal embolization group with 3.9 +/- 3.7 days versus the rest of the patients 2.4 +/- 2.4 days (p = 0.01). In the majority of patients there was no significant adverse clinical outcome.

Coronary embolization after balloon angioplasty or thrombolytic therapy: an autopsy study of 32 cases

OBJECTIVES

This study was undertaken to examine the nature, extent and clinical relevance of coronary embolism after balloon angioplasty or thrombolytic therapy, or both.

BACKGROUND

Histopathologic documentation of postinterventional coronary embolization has been reported in only 10 patients from five studies.

METHODS

This retrospective autopsy-based study included 32 patients, treated with balloon angioplasty or thrombolysis, or both, who died within 3 weeks of the procedure and underwent autopsy at the Mayo Clinic. Clinical variables included patient age and gender, artery treated, site and type of obstruction, type of intervention, success of the procedure, and postprocedural changes in the electrocardiogram (ECG), cardiac enzymes and hemodynamic status. Histopathologic variables included characteristics of treated plaques, acutely infarcted myocardium and coronary microemboli. Associations between microemboli and clinical and microscopic factors were evaluated by t tests and simple and multiple linear regression.

RESULTS

Emboli were observed in 26 (81%) of the 32 patients. Among 83 emboli, 95% were thrombotic or atheromatous. The presence of microemboli was associated statistically with the development of postprocedural infarct extension, new myocardial infarction or new ECG abnormalities. Moreover, the greatest number of microemboli were associated with intervention in the left anterior descending coronary artery, multiple interventional sites, postprocedural medial dissection and plaque rupture or extrusion.

CONCLUSIONS

Among patients undergoing balloon angioplasty or thrombolytic therapy who die and undergo autopsy, coronary microemboli occur in a substantial percent. The frequency in survivors is unknown. However, in living patients who develop acute myocardial ischemia or new ECG abnormalities after these interventions, coronary microembolization should be considered a potential cause.

Angiographic predictors of a rise in serum creatine kinase (distal embolization) after balloon angioplasty of saphenous vein coronary artery bypass grafts

Distal coronary embolization is thought to be increased in the balloon angioplasty of coronary by-pass vein grafts. One hundred fifty-five procedures of balloon angioplasty involving single vein graft dilatation were successfully performed. Distal coronary embolization was defined as an elevation of creatine phosphokinase greater than twice the preangioplasty value and positive MB fraction. Twenty procedures were found to have embolism by this definition. Forty preangioplasty angiograms were randomly selected from the remaining procedures and analyzed as a control group. Eight angiographic features were evaluated as possible risk factors for distal coronary embolization, i.e., diffusely diseased vein graft, presence of thrombus, ulcerated lesion surface, marked eccentricity, large plaque volume, lesion angulation, abrupt proximal face and ectasia. A diffusely diseased vein graft (p = 0.002), presence of thrombus (p = 0.006), irregular or ulcerated lesion surface (p = 0.007), large plaque volume (p = 0.02) and marked eccentricity (p = 0.03) were found to be important predictors by univariate analysis. A diffusely diseased vein graft and a large plaque volume were found to be important independent predictors by multivariate analysis. The presence of thrombus and an irregular or ulcerated lesion surface frequently coexist with a diffusely diseased vein graft. It is concluded that a diffusely diseased vein graft and a large plaque volume are important independent predictors of distal embolization, and thrombus and an ulcerated lesion surface are also important.

Catastrophic thrombus development despite systemic heparinization during coronary angioplasty: possible relationship to nonionic contrast

Two cases of catastrophic thrombus formation during coronary angioplasty occurred shortly after the operators began using nonionic contrast. This occurred despite systemic heparinization, the adequacy of which was documented by activated clotting times (ACT). Both cases were resistant to balloon inflation and one was refractory to intracoronary thrombolysis. There is a considerable body of evidence documenting that low-osmolality contrast media, especially those that are nonionic, have less anticoagulant effect than standard contrast media. Several reports have also been published suggesting possible relationships between nonionic contrast and intravascular thrombus formation during coronary angiography and angioplasty. These data are reviewed and recommendations made for utilization of these contrast media.

A serial observation of coronary thrombi in vivo by a new percutaneous transluminal coronary angioscope

This study was undertaken to observe coronary thrombus formation serially from an antegrade perspective by means of a new thin flexible angioscope that has an inflatable balloon at the distal tip and an angulation mechanism. To test its capabilities, thrombi were induced in the left anterior descending coronary artery of 11 dogs by copper coils, and the thrombi were then observed through this angioscope, which had been introduced into the coronary artery by a guide catheter. Five minutes after insertion of the copper coil, fibrin-like material and white components of the thrombi were seen massing around the copper coil. Then, thin, mixed thrombotic white and red components formed around the copper coil. At fifteen minutes after the copper coil insertion, the thrombi grew in size. Ten minutes later, the thrombi finally obstructed the coronary lumen in most dogs. The red and white appearance of these thrombi was confirmed macroscopically, and the microscopic findings of these occluding thrombi revealed a fibrinous network with platelet aggregates and blood cell coagulation. Though ordinary angiography cannot reveal the precise features of the various coronary thrombi, this new angioscope was able to discern them from the antegrade perspective. The capabilities of this angioscope, which enabled these findings, should prove helpful in evaluating the stages of human coronary thrombosis. Of additional benefit, this angioscope can be used clinically for cardiac catheterization.

Percutaneous transluminal coronary angioplasty for unstable angina

Coronary angioplasty is an effective treatment for patients with angina at rest, either refractory or initially stabilized but returning despite pharmacologic treatment, and with early postinfarction angina. The procedure has a high initial success rate, but there is an increased risk of major complications resulting from a higher incidence of acute closure, which may be related to preexisting thrombus. Resolution of this problem may be achieved by the use of more potent antiplatelet treatment, pretreatment with thrombolytic agents, or treatment that can be applied locally (e.g., laser energy, atherectomy) at the site of the unstable plaque. Results in this study have been obtained from selected groups of patients: those with predominantly single-vessel disease and well-preserved left ventricular function. It remains to be determined whether the same benefits can be achieved in patients with multivessel disease or in those who have severely reduced left ventricular function.

Stenting of coronary arteries: has a modern Pandora's box been opened?

Interventional cardiology has recently witnessed the growth of several alternatives to percutaneous transluminal angioplasty, including coronary stenting. Although stenting appears to be useful in treating abrupt closure after coronary angioplasty, its effectiveness in limiting the complex processes responsible for late restenosis is much less certain. Pathologic examination of stented human saphenous bypass grafts shows extensive deposits of platelets, fibrin and leukocytes along the stent wires within the 1st week and formation of a neointima of variable thickness after 3 months without evidence of foreign body reaction. The long-term effects of continuous barotrauma induced by the expanded stent remain unknown. It is difficult to assess the relative merits of the new devices, but stenting has several theoretic advantages. It seems less disruptive to the underlying architecture of the vessel wall and enjoys favorable theoretic and effective expansion ratios. Wide-spread clinical acceptance for stenting will depend on demonstrating that its safety, efficacy and cost efficiency are superior to those of balloon angioplasty.

Distal embolization during mechanical thrombolysis: rotational thrombectomy vs. balloon angioplasty

To determine the incidence and extent of distal embolization during percutaneous transluminal balloon angioplasty (PTA) and rotational thrombectomy (PRT), we collected, filtered, and weighed the distal effluent of acute thrombotically occluded canine arteries following mechanical thrombolysis. PRT (n = 11) and PTA (n = 10) were equally effective in recanalizing occluded vessels (91% vs. 90%) and reduced percent diameter stenosis to a similar degree (97 +/- 6% to 8 +/- 11% and 100 +/- 0% to 17 +/- 23%, respectively). Distal embolization following mechanical intervention was observed in 10 of 10 and 8 of 9 arteries recanalized with PRT and PTA, respectively. The mean weights of collected emboli were similar between the two groups (18 +/- 24 mg vs. 37 +/- 79 mg, PRT vs. PTA, P = NS), although the range of size and weight of thromboemboli was larger in the PTA group (0-206 mg vs. 2-51 mg, PRT). Angiographically defined residual thrombus was significantly less frequent in arteries recanalized with PRT as compared with PTA (10% vs. 55%, P = 0.03). In summary, PRT and PTA are equally effective in recanalizing acutely occluded canine arteries and result in similar reductions in percent diameter stenosis. Each intervention results in distal embolization of thrombi. PRT is associated with a reduced incidence of angiographically evident residual thrombus at the site of arterial injury and may avoid embolization of large fragments occasionally produced by PTA. Thus PRT may serve as a useful alternative to coronary angioplasty during acute myocardial infarction.

Management of complicated coronary angioplasty by intracoronary urokinase and immediate re-angioplasty

Percutaneous transluminal coronary angioplasty was complicated by acute coronary occlusion, dissection of the arterial wall, or angiographic evidence of intraluminal thrombosis in 33 high-risk patients from 153 consecutive angioplasty procedures (21.5%). Ten patients (group I) were managed with nitroglycerin (0.2 to 0.4 mg i.c.) and repeated attempts at mechanical guide wire recanalization or dilation, but they did not receive thrombolytic therapy. In the remaining 23 patients (group II), intracoronary urokinase (100,000 to 360,000 U.I.) was administered over 15-20 min after onset of coronary occlusion or thrombosis and continued during attempts at repeated dilation of the stenosis. The incidence of sudden coronary artery occlusion was 70% in group I patients and 52% in group II. The angiographic evidence of thrombus formation was observed in a higher, but not significant, proportion of group II patients (65%) as compared with group I (30%). The incidence of intimal tearing or dissection was similar in the two groups of patients (40 vs. 34.7%). The overall final success rate of the complicated angioplasty series was 48% (6/33). However, the success rate was lower (10%) in group I than in group II patients (10 vs. 65%; P less than 0.005), and the frequency of emergency coronary artery bypass grafting was lower in group II patients (13 vs. 60%; P = 0.01), suggesting that thrombolytic therapy with urokinase may be effective in the management of acute coronary occlusion and thromboembolic complications of coronary angioplasty.

Catheter reperfusion for failed emergency coronary angioplasty without subsequent bypass surgery

A transluminal intracoronary reperfusion catheter was used in eight patients, seven with acute myocardial infarction and one with unstable angina after failed emergency coronary angioplasty. After placement of the reperfusion catheter across the occlusion, symptoms of ischemia resolved in each patient. Chest pain recurred 3 hr later in a single patient who underwent successful repeat angioplasty. The catheter was withdrawn within 6 hr after introduction. Control coronary angiography showed a patent vessel in all but one. Repeat angioplasty or bypass surgery was unnecessary. During 1 year mean follow-up time all patients remained free of symptoms. The reperfusion catheter is a safe and effective means of perfusing a coronary artery after failure of thrombolytic therapy and coronary angioplasty in cases where emergency bypass surgery is not performed because operative morbidity is expected to outweigh the benefit of myocardial salvage, or when it cannot be immediately organized.

Rotational thrombectomy in acute canine coronary thrombosis

We have developed a mechanical thrombolytic catheter which defibrinates a fresh intra-arterial thrombus by wrapping fibrin about its rotating shaft. Defibrination results in liquification of the thrombus and reperfusion of the thrombotically occluded vessel. In this study, we employed this catheter-based approach in dogs with coronary thrombosis to simulate possible clinical use in acute myocardial infarction. Total coronary thrombosis was generated in 11 dogs. Spontaneous reperfusion did not occur over a 30-minute control period. All vessels studied were initially totally thrombosed. After mechanical thrombolysis, there was a significant improvement in percent diameter stenosis from 100% to 28 +/- 26% (P less than 0.001). After thrombolysis, angiographically graded blood flow was normal in 9 of 11 arteries and was mildly delayed in 2 of 11. Complications included perforation of 2 vessels. We conclude that mechanical thrombolysis, with a rotating catheter, results in prompt reperfusion of the infarct vessel and significant improvement in distal blood flow. This approach, unlike angioplasty, removes the thrombus and might serve as an alternative to or supplemental form of mechanical thrombolysis.

Balloon angioplasty of aortocoronary saphenous vein bypass grafts: a histopathologic study of six grafts from five patients, with emphasis on restenosis and embolic complications

Among 103 patients undergoing percutaneous transluminal balloon angioplasty of obstructed aortocoronary saphenous vein bypass grafts at the Mayo Clinic, six grafts from 5 patients were available for histopathologic examination. The interval from graft insertion to angioplasty ranged from 5 to 105 months and that from angioplasty to graft excision ranged from 6 h to 24 months. Angioplasty produced intimal fissures in three grafts initially obstructed by intimal fibromuscular proliferation. Healing and restenosis resulted from filling of lacerations with fibrocellular tissue and apparently also from restitution of muscular tone. In two of three grafts initially narrowed by atherosclerosis, balloon angioplasty cause extensive plaque rupture and restenosis resulted from extrusion of plaque debris and secondary luminal thrombosis. In the third graft, angioplasty produced no distinct lesions and late restenosis was due to progressive atherosclerosis of the vein graft. Atheroembolization was observed in both patients with plaque rupture and was associated with reoperation in one and death in the other. In conclusion, the results derived from six saphenous vein bypass grafts subjected to balloon angioplasty indicate that restenosis may result from intimal fibrocellular proliferation, thrombosis, restitution of muscular tone and progressive atherosclerosis. Symptomatic atheroembolization may occur in grafts greater than 1 year old.

Coronary angioplasty for unstable angina: immediate and late results in 200 consecutive patients with identification of risk factors for unfavorable early and late outcome

Two hundred patients (mean age 56 years, range 36 to 74) with unstable angina (chest pain at rest, associated with ST-T changes) underwent coronary angioplasty. In 65 patients with multivessel disease, only the "culprit" lesion was dilated. The initial success rate was 89.5% (179 of 200 patients). At least one major procedure-related complication occurred in 21 patients (10.5%): (death in 1, myocardial infarction in 16 and urgent surgery in 18). All patients were followed up for 2 years. Five patients died late; 8 had a late nonfatal myocardial infarction and 52 had recurrence of angina pectoris. The restenosis rate was 32% (51 of 158) in the patients with initial successful angioplasty who had repeat angiography. At the 2 year follow-up, after attempted coronary angioplasty in all 200 patients, the total incidence rate of death was 3% (one procedure related; five late deaths), of nonfatal myocardial infarction 12% (16 procedure related and 8 late after angioplasty), and 13% (26 patients) were still symptomatic although they had improved in functional class. Multivariate analysis showed that variables indicating an increased risk 1) for major procedure-related complications were: ST segment elevation, persistent negative T wave and stenosis greater than or equal to 65% (odds ratio 3.7, 3.7 and 3.3, respectively); 2) for angiographic restenosis were: presence of collateral vessels, ST segment depression, multivessel disease, left anterior descending coronary artery stenosis and history of recent onset of symptoms (odds ratio: 2.2, 2.0, 1.9, 1.9 and 0.54, respectively); and 3) for late coronary events (recurrence of angina, late myocardial infarction or late death) were: multivessel disease, total occluded vessel and ST segment elevation (odds ratio 3.7, 2.8 and 0.44, respectively). Thus, coronary angioplasty for unstable angina can be performed with a high initial success rate, but at an increased risk of major complications. The prognosis is favorable after initial successful coronary angioplasty.

Transluminal intracoronary reperfusion catheter: a device to maintain coronary perfusion between failed coronary angioplasty and emergency coronary bypass surgery

The reperfusion catheter is a 4.3F catheter with 30 holes over its distal 10 cm. It is used to maintain coronary blood flow in patients awaiting emergency coronary bypass surgery after failed coronary angioplasty. The insertion of the reperfusion catheter was attempted in 20 patients (14 with total occlusion and 6 with severe residual stenosis judged to be in jeopardy of reclosure before operation). The reperfusion catheter was successfully placed across the obstruction in 18 patients (90%). After successful insertion of the reperfusion catheter, 16 patients had good anterograde flow (Thrombolysis in Myocardial Infaction [TIMI] trial grade II or III); angiographic improvement was associated with significant lessening of ST segment elevation as well as a decrease in chest pain in most patients. Two patients had poor or absent anterograde flow (TIMI grade O or I) because of extensive preexisting intracoronary thrombosis; one died from refractory ventricular fibrillation. In each of the remaining patients emergency coronary bypass surgery was performed with no deaths or significant cardiac complications. The reperfusion catheter is a safe and effective method to reestablish and maintain coronary blood flow before coronary bypass surgery after failed coronary angioplasty. Because there is the potential risk of serious complications, particularly thrombus formation within this catheter, the reperfusion catheter should be used cautiously and the patient should undergo immediate bypass surgery.

Entrapment of an angioplasty balloon catheter: a case report

This report presents a case in which an angioplasty balloon catheter became entrapped within the lumen of a coronary artery after rupture during percutaneous transluminal coronary angioplasty (PTCA). Prior to this report, balloon rupture had been considered a relatively benign occurrence. However, this case demonstrates that balloon rupture may lead to serious complications.

Pathological changes induced by repeated percutaneous transluminal coronary angioplasty

The histopathological appearances of seven coronary arteries obtained from four patients after repeated percutaneous transluminal coronary angioplasty were analysed. A complex picture was found; typically there were ruptured atherosclerotic plaques, plaque dissection, and a fibrous tissue response. The histopathological appearance of older and more recent fibrous lesions was different. Older lesions contained more collagen and elastin fibres, whereas recent ones had more loosely arranged connective tissue containing abundant glycosaminoglycan and readily identifiable cells. The fibrous tissues tended to be damaged at the sites of previous injury and where the vessel wall was thinnest. In five of the seven arteries there was evidence of a repeated fibrous response to injury with partial or total rupture of the original media. In one instance a repair response within a pre-existing atherosclerotic plaque had caused restenosis. The results indicate that restenosis after repeated percutaneous transluminal coronary angioplasty, like restenosis after a first procedure, is mainly the result of fibrocellular tissue response to injury of the wall tissues. Because older (that is more mature) repair tissue contains fewer cells and more connective elements than younger repair tissue (that is the loosely arranged connective tissue found soon after angioplasty), when it is disrupted by a further angioplasty procedure it is less capable of producing tissue that will obstruct the lumen. This may explain why in the majority of patients with restenosis repeated percutaneous transluminal coronary angioplasty is successful. The present study also showed that occasionally plaque haemorrhages may become organised and incorporated into the pre-existing atherosclerotic lesion.

Mechanical thrombectomy: a comparison of two rotational devices and balloon angioplasty in subacute canine femoral thrombosis

In this study, two prototype rotational devices were compared to balloon angioplasty in a canine model of subacute arterial thrombosis. Radiographic 2- to 8-day-old total thrombotic occlusions were produced in 30 canine femoral arteries. A high-speed rotating device with a cutting tip was used in 18 arteries. Successful opening occurred in every case, with a residual percent diameter stenosis at 45 +/- 25%. Vessel perforation was seen in 6 of the 18 arteries. A noncutting rotational thrombectomy catheter was used in six arteries. Radiographic patency was established in two of six (residual stenosis 86 +/- 28%), with one perforation with the use of the noncutting thrombectomy catheter. Balloon angioplasty reestablished radiographic patency in three of six arteries (residual stenosis 77 +/- 2%). No perforations were seen with balloon dilation, but radiographic distal emboli were always observed. No radiographic emboli were observed with either of the rotational devices. We conclude that subacute arterial thromboses are easily opened with an abrasive-tipped rotating angioplasty device. Although perforations are relatively common with this prototype equipment, design changes may produce a clinically useful angioplasty device.

Aspirin and dipyridamole in the prevention of acute coronary thrombosis complicating coronary angioplasty

To test the hypothesis that pretreatment with adequate antiplatelet therapy reduces the likelihood of acute coronary thrombosis during routine percutaneous transluminal coronary angioplasty (PTCA), we reviewed, blinded to treatment group, the films and records of 300 consecutive initially successful PTCAs. Films before PTCA, immediately after, and at least 30 min after the last balloon inflation were assessed for the presence of any thrombus at the PTCA site. We excluded 37 patients who received streptokinase before PTCA or who had 100% occlusion or thrombus on pre-PTCA films. New thrombi were classified as clinically significant (defined as causing 100% occlusion or requiring emergency surgery or streptokinase therapy) or as not significant (not causing an acute problem or requiring intervention). Patients were classified into three groups, based on the type and extent of antiplatelet therapy received. Group 1 (no aspirin, n = 121) consisted of patients who did not receive aspirin either before admission or in hospital before PTCA (with or without dipyridamole). Group 2 (standard treatment, n = 110) received aspirin with or without dipyridamole but did not receive both drugs before admission and in hospital before PTCA. Group 3 (maximal treatment, n = 32) received both aspirin and dipyridamole before admission and in hospital before PTCA. New thrombi were detected at 39 (14.8%) PTCA sites, of which 15 (5.7% of all PTCA sites) were considered clinically significant. Group 1 had the highest incidence of both thrombus (21.5%) and clinically significant thrombus (10.7%). A reduction was seen in group 2 in thrombus (11.8%; p = .07) and in clinically significant thrombus (1.8%; p = .005). Group 3 had no thrombus (p = .001) and no clinically significant thrombus (p = .04). In addition to inadequate pretreatment with antiplatelet therapy, univariate analyses demonstrated several other risk factors for thrombus: higher percent diameter stenosis before PTCA (p less than .008), higher platelet count (p = .013), and current smoking (p = .03). Only higher platelet count (p less than .001) and inadequate pretreatment (p = .001) were associated with clinically significant thrombus. Stepwise logistic regression analysis demonstrated that for thrombus, the lack of effective antiplatelet therapy was the most discriminatory variable, followed by current smoking, higher percent diameter stenosis, and dissection. For clinically significant thrombus, once the lack of pretreatment with effective antiplatelet therapy was considered, no other factors added significant discriminatory information.(ABSTRACT TRUNCATED AT 400 WORDS)

The spectrum of pathology associated with percutaneous transluminal coronary angioplasty during acute myocardial infarction

The purpose of this study was to determine at necropsy the morphologic consequences of percutaneous transluminal coronary angioplasty performed during acute myocardial infarction. The heart was examined in four patients who died between 6 hours and 4 days after coronary angioplasty. The patients had angioplasty of the left main coronary artery (one patient), left anterior descending coronary artery (two patients) and left circumflex coronary artery (one patient). Necropsy revealed residual stenosis, intimal hemorrhage and plaque disruption in all four patients. Also noted were distal embolization of plaque elements (two patients) and thrombotic occlusion of the coronary artery (one patient). In conclusion, the morphologic changes after angioplasty are varied. These changes illustrate the mechanisms of angioplasty and some of the complications that can be expected in a small number of cases. The morphologic changes associated with coronary angioplasty are similar in patients undergoing elective or emergency angioplasty although medial dissection was not observed in these patients with an evolving myocardial infarction.

Embolization complicating coronary angioplasty in the presence of an intracoronary thrombus

Two cases of coronary occlusion and subsequent embolization during percutaneous coronary angioplasty (PTCA) are described. Prior to PTCA, angiographic evidence of intracoronary thrombus was present. Abrupt reclosure after dilation was treated by successful redilation. However, coronary embolization of thrombus debris occurred downstream in one patient and into an adjacent coronary branch in the second patient.