Thrombus Aspiration With Microcatheter for Distal Embolization During Primary Angioplasty for Acute Myocardial Infarction: Technical Notes

Abstract: We describe a new technique for removing distal emboli that became visible on angiography during percutaneous coronary intervention for acute myocardial infarction. Three patients presented with distal embolization as a filling defect with an abrupt cut-off in 1 of the peripheral coronary vessels of the infarct-related coronary artery. After a failed attempt to retrieve the thrombus with a conventional aspiration catheter, the thrombus was trapped at the tip of a microcatheter by aspiration and was successfully retrieved. This procedure can achieve prompt restoration of distal coronary flow.

J INVASIVE CARDIOL 2012;24(11):618-621

Key words: microcatheter, aspiration, distal embolism

__________________________________________________________

Early revascularization with percutaneous coronary intervention (PCI) and adjunctive pharmacologic therapy has improved the outcome of patients with acute myocardial infarction (AMI). However, even after conventional primary PCI with stent placement and glycoprotein IIb/IIIa blockade, two-thirds of such patients show impaired myocardial perfusion.¹ One of the main causes of impaired reperfusion is distal embolization that develops during the PCI procedure. This distal embolization occurs in either the microvasculature of the myocardium or the epicardial coronary arteries located distally to the culprit lesion, which can be visualized by coronary angiography (CAG). To prevent the development of a distal embolism in the microvasculature, thrombus aspiration before predilatation and distal protection are usually performed; to prevent the development of a distal embolism in the epicardial coronary arteries, additional aspiration or pharmacologic treatment is usually performed. However, for embolisms in the epicardial arteries, aspiration with a conventional aspiration catheter often fails due to a lack of deliverability of the catheter. Thrombolysis may be an effective alternative; however, this treatment option is associated with problems related to its credibility and promptness. In this paper, we present a novel technique for the removal of a thrombus occluding the distal coronary artery branch, as seen during primary angioplasty, by using a microcatheter.

Technique Description

When a conventional thrombectomy catheter fails to access the occlusion site of the distal embolism, this novel procedure may be applied. After a floppy guidewire is crossed through the distal embolism (Figure 1A), a Rapid Transit microcatheter (Codman & Shurtieff, Inc) is advanced, whereafter the guidewire is retrieved. A VacLock vacuum syringe (Merit Medical Systems, Inc) is connected to the microcatheter and aspiration is initiated (Figure 1B). Aspiration becoming blocked is indicative that the thrombus has been caught by the tip of the microcatheter. The microcatheter is moved backward slowly (Figures 1C and 1D), and finally, the thrombus caught at the tip of the microcatheter is removed outside.

Case 1

A 77-year-old man was admitted to our hospital with sudden chest pain. He had hypertension as a coronary risk factor. The electrocardiogram (ECG) showed ST-segment elevation in the inferior leads. One month before admission, he had undergone elective PCI because of unstable angina with severe stenosis in the right coronary artery (RCA). At that time, 2 Endeavor stents (Medtronic) were placed in segments #2 and #3. Emergency CAG upon hospitalization revealed total occlusion in the proximal Endeavor stent, which was placed in segment #2. A 6 Fr Launcher SAL 1.0 (Medtronic) was engaged in the RCA. The thrombus was aspirated with an Eliminate aspiration catheter (Terumo) after the lesion was crossed with a Runthrough guidewire (Terumo). Next, the lesion was well dilated with a 3.5 x 14 mm balloon catheter; however, the posterior descending artery showed occlusion in its mid-portion (Figure 2A). We therefore advanced the guidewire to the posterior descending artery, followed by a Rapid Transit microcatheter (Figure 2B). After retrieving the wire, we connected a VacLock syringe and drew the plunger. After confirming that aspiration was blocked, we slowly pulled back the microcatheter. We successfully removed the thrombus attached to the tip of the Rapid Transit microcatheter (Figure 2C). The final angiogram showed thrombolysis in myocardial infarction trial (TIMI) grade 3 flow without residual stenosis or dissection in the occluded artery (Figure 2D).

Case 2

A 66-year-old man was admitted to our hospital with occasional chest pain that had persisted for 1 week. He had hypertension as a coronary risk factor. ECG showed significant ST-segment depression in V4-6. Emergency CAG revealed total occlusion in the mid-portion of the left circumflex artery. After thrombus aspiration with an Eliminate aspiration catheter, the lesion was predilated with a 2.5 x 15 mm balloon catheter, and then a 3.0 x 18 mm Driver stent (Medtronic) was deployed. The lesion was well dilated; however, occlusion with an embolism was observed in the distal part of 1 branch (Figure 3A). The thrombus was successfully aspirated with a Rapid Transit microcatheter using the same procedure as that described for Case 1 (Figure 3B). The final angiogram showed TIMI grade 3 flow without residual stenosis or dissection in the occluded lesion (Figure 3C).

Case 3

An 82-year-old woman presented with sudden chest pain and was admitted to our hospital by ambulance. Before arriving at the hospital, she developed ventricular fibrillation and underwent successful resuscitation. ECG showed ST-segment elevation in V2-6. Emergency CAG revealed subtotal occlusion in the proximal part of the left anterior descending artery (LAD). After crossing a Runthrough guidewire, we attempted to advance an Eliminate aspiration catheter; however, the catheter became stuck before reaching the lesion because of calcification. After balloon dilatation with an AngioSculpt catheter (Medtronic) with 14 atm, a 3.0 x 15 mm Driver stent was deployed. The lesion was well dilated, but the LAD showed the presence of a distal embolism (Figure 4A). The previously used Eliminate aspiration catheter was again advanced; however, the tip of the catheter could not reach the distal embolism (Figure 4B). The thrombus was aspirated successfully with a Rapid Transit microcatheter, as in the previous 2 cases. The final angiogram showed TIMI grade 3 flow with no significant stenosis in the occluded lesion (Figure 4C).

All 3 patients were successfully managed after primary PCI and discharged without sequelae.

Discussion

In this paper, we describe the efficacy of aspiration with a microcatheter for the removal of a distal embolism after primary PCI in 3 patients. The embolism, visualized by CAG with contrast medium as an abrupt cut-off filling defect, occurred in a distal branch of the infarct-related artery in all 3 patients. Although the Rapid Transit microcatheter does not have a sufficiently large inner lumen to aspirate a thrombus in the coronary artery (0.021˝), it can be advanced deep into the distal part of an infarct-related artery with its small profile (0.75 mm) and trap a thrombus using the vacuum effect. Thus, this technique can retrieve a thrombus far distal to the culprit lesion. Distal embolisms have been reported to be a major complication of primary PCI and are considered the main cause of inadequate myocardial perfusion despite restoration of epicardial flow in the infarct-related artery. This complication occurs in a peripheral part of the infarct-related artery, such as the distal artery, side branch, or microcirculation, depending on the size of the embolic material. The use of thrombectomy catheters before balloon dilatation reduces the incidence of distal embolization, with the largest thrombectomy trial reporting improved outcomes with regard to cardiac death and major cardiac adverse events.^2,3 However, thrombectomy catheters currently available are designed for culprit lesions in the proximal coronary artery and are not suitable for distal emboli such as those described in this report. Accordingly, if a distal embolism occurs in the infarct-related artery, conventional thrombectomy catheters often fail to remove the thrombus.

When embolization occurring in the distal part of the coronary vascular tree is left untreated, the consequences are severe. Henriques et al⁴ reported the clinical significance of distal embolization during primary PCI. They studied 178 patients with AMI treated with PCI. Of these patients, 27 (15.2%) presented with an embolism in the distal artery, showing a distal filling defect with an abrupt cut-off in one of the peripheral coronary arteries; these patients showed significantly worse outcomes in terms of enzyme leakage, left ventricular ejection fraction, and long-term mortality compared with patients without a distal embolism.

Treating a distal embolism is cumbersome. Several therapeutic options may be considered, including additional pharmacotherapeutic measures^5,6 or thrombectomy with a laser catheter⁷ or ultrasound catheter.^8,9 However, in contrast with these therapeutic options, the novel technique described here is performed easily, safely, and cost-effectively, and most importantly, provides instant recovery of coronary blood flow. Thus, this technique should be considered a valuable option for the treatment of a distal embolism during primary angioplasty.

Conclusion

Thrombectomy for a distal embolism in the coronary artery with a microcatheter is feasible and effective in patients with acute myocardial infarction after failed thrombectomy with a conventional aspiration catheter. This novel technique may contribute to a better clinical outcome in patients with a distal embolism observed during primary angioplasty.

References

1. Stone GW, Peterson MA, Lansky AJ, et al. Impact of normalized myocardial perfusion after successful angioplasty in acute myocardial infarction. J Am Coll Cardiol. 2002;39(4):591-597.
2. Svilaas T, Vlaar PJ, van der Horst IC, et al. Thrombus aspiration during primary percutaneous coronary intervention. N Engl J Med. 2008;358(6):557-567.
3. Vlaar PJ, Svilaas T, van der Horst IC, et al. Cardiac death and reinfarction after 1 year in the thrombus aspiration during percutaneous coronary intervention in acute myocardial infarction study (TAPAS): a 1-year follow-up study. Lancet. 2008;371(9628):1915-1920.
4. Henriques J, Zijlstra F, Ottervanger J, et al. Incidence and clinical significance of distal embolization during primary angioplasty for acute myocardial infarction. Eur Heart J. 2002;23(14):1112.
5. Neumann FJ, Kastrati A, Schmitt C, et al. Effect of glycoprotein IIb/IIIa receptor blockade with abciximab on clinical and angiographic restenosis rate after the placement of coronary stents following acute myocardial infarction. J Am Coll Cardiol. 2000;35(4):915-921.
6. Ito H, Taniyama Y, Iwakura K, et al. Intravenous nicorandil can preserve microvascular integrity and myocardial viability in patients with reperfused anterior wall myocardial infarction. J Am Coll Cardiol. 1999;33(3):654-660.
7. Topaz O, Bernardo NL, Shah R, et al. Effectiveness of excimer laser coronary angioplasty in acute myocardial infarction or in unstable angina pectoris. Am J Cardiol. 2001;87(7):849-855.
8. Rosenschein U, Furman V, Kerner E, et al. Ultrasound imaging-guided non-invasive ultrasound thrombolysis: preclinical results. Circulation. 2000;102(2):238-245.
9. Brosh D, Bartorelli AL, Cribier A, et al. Percutaneous transluminal therapeutic ultrasound for high-risk thrombus-containing lesions in native coronary arteries. Cathet Cardiovasc Interv. 2002;55(1):43-49.

__________________________________________________________

From the Department of Cardiology, Sakurakai Takahashi Hospital, Kobe, Hyogo, Japan.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Manuscript submitted February 28, 2012 and accepted March 20, 2012.
Address for correspondence: Akihiko Takahashi, MD, PhD, Department of Cardiology, Sakurakai Takahashi Hospital, 5-18-1, Oikecho, Suma-ku, Kobe, Hyogo 654-0026, Japan. Email: a-takahashi@wine.ocn.ne.jp