High frequency rotational ablation: an alternative in treating coronary artery stenoses and occlusions

Analysis of Location and Pattern of Target Vessel Failure in Chronic Total Occlusions after Stent Implantation and Its Potential for the Efficient Use of Drug-Eluting Stents

OBJECTIVES

The recanalization of chronic total occlusions (CTOs) is a complex procedure with high rates of target vessel failure (TVF), i.e., restenosis or reocclusion. Little is known about the localization of lesion recurrence, and whether extensive stenting should be performed. In this prospective analysis, the area at high risk for restenoses after recanalization of CTO was localized.

METHODS

Angiograms of 97 consecutive patients and control angiograms after a mean period of 5 +/- 1.3 months were analyzed for location and length of the CTO and the sites of recurrences.

RESULTS

In total, 158 stents were implanted (1.6 +/- 0.9 per lesion). Restenoses occurred in 39% and reocclusions in 17% of the patients. Patients with a TVF had a longer CTO than patients without TVF (17.9 +/- 10.2 vs 13.9 +/- 8.6 mm; P = 0.023). The TVF rate increased with the number of implanted stents. The stent diameter was smaller in lesions with subsequent reocclusions than in restenotic and nonrestenotic lesions (2.8 +/- 0.5 vs 3.0 +/- 0.4 and 3.2 +/- 0.4 mm resp.; P = 0.007). Analyzing the localization of the 38 restenoses, we only found 45% restricted to the area of the former CTO, while 82% were located in the area of the former CTO plus 10 mm in proximal and distal direction.

CONCLUSIONS

Stents should not only cover the site of the CTO, but should enclose the high-risk area of recurrence within 10 mm proximal and distal of the former CTO. This may guide the rational use of drug-eluting stents.

High Prevalence of Occult Coronary Artery Stenosis in Patients with Chronic Kidney Disease at the Initiation of Renal Replacement Therapy: An Angiographic Examination

The prevalence of coronary artery stenosis (CAS) at the initiation of renal replacement therapy (RRT) in patients with chronic kidney disease (CKD) and no previous history of angina and/or myocardial infarction (MI) has not been fully elucidated. The prevalence of significant CAS was evaluated in 30 asymptomatic stage 5 CKD patients without a history of angina and/or MI by coronary angiography at the initiation of RRT. The correlations of various parameters with the prevalence of CAS were also examined. Atherosclerotic surrogate markers, including intima-media thickness of carotid artery and ankle-brachial BP index (ABI), were also evaluated. Significant CAS (>50% stenosis) was seen in 16 (53.3%) of 30 asymptomatic CKD patients on coronary angiography at the start of RRT. Stress cardiac scintigraphy was not effective for detecting hidden cardiac ischemia among the CKD patients. Univariate analysis showed that diabetes (P = 0.01), left ventricular mass index (P = 0.04), hyperlipidemia (P = 0.04), total cholesterol (P = 0.02), LDL cholesterol (P < 0.01), intima-media thickness (P = 0.04), and fibrinogen (P = 0.01) were positively correlated with the presence of CAS, whereas ABI (P < 0.01) showed a negative correlation with CAS. Stepwise logistic regression analysis revealed that diabetes and fibrinogen were significant and independent risk factors for CAS in asymptomatic CKD patients who started RRT. The results clearly demonstrated that despite the absence of cardiac events, stage 5 CKD patients are already in a very high risk group for CAS at the initiation of RRT, which was also closely associated with a significant decrease in ABI.

Coronary microembolization--its role in acute coronary syndromes and interventions

The diagnosis coronary artery disease is classically based on patient's symptoms and morphology, as analyzed by angiography. The importance of risk factors for the development of coronary atherosclerosis and disturbance of coronary vasomotion is clearly established. However, microembolization of the coronary circulation has also to be taken into account. Microembolization may occur as a single or as multiple, repetitive events, and it may induce inflammatory responses. Spontaneous microembolization may occur, when the fibrous cap of an atheroma or fibroatheroma (Stary i.v. and Va) ruptures and the lipid pool with or without additional thrombus formation is washed out of the atheroma into the microcirculation. Such events with progressive thrombus formation are known as cyclic flow variations. Plaque rupture occurs more frequently than previously assumed, i.e. in 9% of patients without known heart disease suffering a traffic accident and in 22% of patients with hypertension and diabetes. Also, in patients dying from sudden death microembolization is frequently found. Patients with stable and unstable angina show not only signs of coronary plaque rupture and thrombus formation, but also microemboli and microinfarcts, the only difference between those with stable and unstable angina being the number of events. Appreciation of microembolization may help to better understand the pathogenesis of ischemic cardiomyopathy, diabetic cardiomyopathy and acute coronary syndromes, in particular in patients with normal coronary angiograms, but plaque rupture detected by intravascular ultrasound. Also, the benefit from glycoprotein IIb/IIIa receptor antagonist is better understood, when not only the prevention of thrombus formation in the epicardial atherosclerotic plaque, but also that of microemboli is taken into account. Microembolization also occurs during PTCA, inducing elevations of troponin T and I and elevations of the ST segment in the EKG. Elevated baseline coronary blood flow velocity, as a potential consequence of reactive hyperemia in myocardium surrounding areas of microembolization, is more frequent in patients with high frequency rotablation than in patients with stenting and in patients with PTCA. The hypothesis of iafrogenic microembolization during coronary interventions is now supported by the use of aspiration and filtration devices, where particles with a size of up to 700 microns have been retrieved. In the experiment, microembolization is characterized by perfusion-contraction mismatch, as the proportionate reduction of flow and function seen with an epicardial stenosis is lost and replaced by contractile dysfunction in the absence of reduced flow. The analysis of the coronary microcirculation, in addition to that of the morphology and function of epicardial coronary arteries, and in particular appreciation of the concept of microembolization will further improve the understanding of the pathophysiology and clinical symptoms of coronary artery disease.

A new thrombectomy catheter device (AngioJet) for the disruption of thrombi: An in vitro study

In this study we examined a new thrombectomy catheter device. Different kinds of in vitro generated thrombi and cadaver thrombi were disrupted in test tubes. The mean disruption rate (and disruption time for 1 g of thrombus) was 225 +/- 65 mg/sec (5 +/- 2 sec) for whole-blood, 117 +/- 60 mg/sec (12 +/- 9 sec) for fibrin, 41 +/- 18 mg/sec (30 +/- 18 sec) for mixed, 70 +/- 42 mg/sec (17 +/- 5 sec) for unorganized, 45 +/- 8 mg/sec (22 +/- 4 sec) for partly, and 5 +/- 1 mg/sec (216 +/- 29 sec) for completely organized cadaver thrombi (P < 0.05). More than 99% of fragmented particles of whole-blood thrombi were 0-12 microm in diameter. The particle size of fibrin, mixed, and cadaver thrombi was similar, with 25%-40% of particles between 0-12 microm, 55%-71% >12-24 microm, and 2%-7% >24 microm. The device may be effectively used in the therapy of massive pulmonary embolism or acute peripheral and coronary artery syndromes when medical thrombolysis is contraindicated and organization of thrombus is absent. Further studies need to be performed to investigate the potential effects of particle microembolization. Cathet. Cardiovasc. Intervent. 47:381-389, 1999.

[Rotational atherectomy: technique, indications, results]

Rotational atherectomy (Rotablation) represents one of the alternative devices to treat complex coronary artery stenoses. Rather than increasing luminal diameter by arterial stretching and plaque fracture as with balloon angioplasty, rotablation debulks atherosclerotic plaque with an abrasive diamond coated burr. The basic physical principle is differential cutting. It allows the advancing burr to selectively cut inelastic material while elastic tissue deflects away from the burr. 95% of the particles generated by the Rotablator are less than 5 microns. They are removed by the body's reticuloendothelial system. There are different strategies to perform a rotablation, regarding the number of burrs used and the final burr-to-artery ratio. An adjunctive PTCA is recommended without proof by randomized studies so far. The best indication for the Rotablator is the undilatable lesion. Lesion modification (debulking) as a method of improving vessel compliance seems to be also usefull in diffusely diseased and calcified vessels, as well as in aorto-ostial and angulated stenoses. The instent restenoses is a new indication. Randomized studies will have to proof if there is an advantage for rotablation compared to PTCA. Restenosis rates appear comparable to balloon angioplasty.

Effect of Rotablator atherectomy and adjunctive balloon angioplasty on coronary blood flow

BACKGROUND

The purpose of this study was to assess serial changes in coronary blood flow velocity before and after Rotablator atherectomy and after adjunctive percutaneous transluminal coronary angioplasty (PTCA). Since Rotablator atherectomy results in luminal enlargement by plaque pulverization and distal embolization, improvement in coronary blood flow could be attenuated despite luminal enlargement.

METHODS AND RESULTS

Intracoronary Doppler blood flow velocity measurements were obtained with a Doppler Flowire. Basal average peak velocity (bAPV), hyperemic APV (hAPV), diastolic/systolic velocity ratio (DSVR), and coronary flow reserve (CFR) were assessed before intervention, after Rotablator, and after adjunctive PTCA. Complete clinical, angiographic, and Doppler data were obtained in 22 patients. There was a small but significant difference (P = .02) in resting heart rate and mean arterial pressure before and after Rotablator and after adjunctive PTCA. Minimum lumen diameter increased from 0.8 +/- 0.1 to 1.5 +/- 0.2 to 2.0 +/- 0.1 mm (P < .001), corresponding to decreases in diameter stenosis from 72 +/- 3% to 41 +/- 4% to 36 +/- 3% (P < .001). Although bAPV, hAPV, and DSVR increased significantly (P < .001), CFR remained abnormally low in 19 of 22 patients (despite an increase from baseline to post-PTCA). hAPV > 30 cm/s was the best Doppler correlate of angiographic success.

CONCLUSIONS

Rotablator atherectomy and adjunctive PTCA significantly improve distal coronary blood flow velocity and DSVR but not CFR. Failure to normalize CFR could be secondary to parallel increases in bAPV and hAPV, "acquired" microvascular disease due to distal microembolization or spasm, and/or angiographically inapparent dissection or residual stenosis. Adjunctive PTCA contributes significantly to the overall physiological benefit of a combined procedure.

Outcome of narrowing related side branches after high-speed rotational atherectomy

High-speed rotational atherectomy (HSRA) is advocated for calcified and diffusely narrowed coronary arteries. There are often side branches involving these kinds of lesions. The presence of significant lesion-related side branches has been considered a relative contraindication to rotational atherectomy. This study was performed to determine the rate, predictors, and outcome of side branch occlusion after HSRA. The angiograms of 418 patients were examined with 320 side branches in 240 target vessels of > or = 1 mm in diameter being identified. Vessels were scored as either perfused (Thrombolysis In Myocardial Infarction 2 or 3 flow) or occluded (Thrombolysis In Myocardial Infarction 0 or 1 flow before and after the procedure. A detailed quantitative angiographic analysis was performed on a total of 108 side branches including all cases of branch occlusion. Clinical outcomes were determined in all cases with side branch loss. There were 24 occlusions in 21 patients after the procedure, giving a rate of branch loss of 7.5%. Follow-up angiography of > or = 24 hours was available for 13 of the occluded branches and 12 were found to be patent. In the 21 patients with branch occlusion, 6 sustained a myocardial infarct (of which 5 were non-Q-wave), 2 underwent coronary artery bypass grafting, and 2 died. There are frequently lesion-associated side branches in the types of vessels to undergo HSRA. These branches remained patent 92.5% of the time, with occlusion occurring infrequently and usually being transient. When occlusion did occur, there was a 29% incidence of myocardial infarction.

Mechanism of high-speed rotational atherectomy and adjunctive balloon angioplasty revisited by quantitative coronary angiography: edge detection versus videodensitometry

High-speed rotational coronary atherectomy (RA) is primarily used to treat complex lesions. Quantitative angiographic analysis of such complex lesions by edge detection is often unsuitable, whereas videodensitometry, measuring vessel dimensions independently of the target stenosis contours, may offer potential advantages. To gain insight into the operative mechanism of RA and to study the agreement between the two quantitative angiographic methods in measuring the minimal luminal cross-sectional area, the edge detection and videodensitometry techniques were applied to coronary angiograms of 21 lesions in 19 patients with symptoms who underwent successful RA and balloon angioplasty (BA). Obstruction diameter as determined by edge detection increased from 1.00 +/- 0.31 mm before intervention to 1.35 +/- 0.29 mm after RA (p < 0.001) and further increased to 1.74 +/- 0.33 mm after adjunctive BA (p > 0.001). The mean between-method difference (edge detection minus videodensitometry) was 0.34 mm2 before intervention, 0.13 mm2 after RA, and 0.09 mm2 after adjunctive BA (not significant). The standard deviation of the differences decreased from +/- 0.87 mm2 before intervention to +/- 0.80 mm2 after RA (not significant) and increased after BA significantly to +/- 1.21 mm2 (p < 0.05). Thus edge detection and videodensitometry provided equivalent immediate angiographic results after RA and adjunctive BA. The good agreement after RA may reflect the operative mechanism of RA, which by ablation of noncompliant plaque material yields a circular symmetric lumen with smooth surface. The increased dispersion of the between-method differences observed after adjunctive BA presumably results from dissections, plaque ruptures, and loss of luminal smoothness after balloon dilatation.

Coronary artery morphologic features after coronary rotational atherectomy: insights into mechanisms of lumen enlargement and embolization

The coronary arteries and myocardium from two patients who died after coronary rotational atherectomy were analyzed to gain insights into the mechanisms of lumen enlargement and to document embolization of calcified plaque. Rotational atherectomy resulted in sharp cuts in plaque, producing a relatively smooth luminal surface. When extensive nodular calcific atherosclerosis was present, the luminal surface was focally uneven with exposure of jagged calcified plaque to blood flow. Deep plaque fissures and medial dissections were also seen. These fissures may have been created by the rotoblator or by adjunctive balloon angioplasty. Multiple calcific atheroemboli were present after rotoblator use in plaques containing extensive nodular calcification; in moderately calcified plaque only one small atheroembolus was found. Thus embolization of calcified plaque can occur after rotational atherectomy and may correlate with the severity of plaque calcification. Rotational atherectomy produces a focally smooth, sharp-edged, luminal surface, a lumen enlargement mechanism different from balloon angioplasty.

Case report: A new guidewire for coronary rotational ablation

We report three cases using a new guidewire designed for coronary rotational ablation. The tips are .014 in diameter and available in different degrees of flexibility. The improved torquability of these guidewires may improve the success rate of coronary rotablation in select cases.

High-frequency rotational ablation following failed percutaneous transluminal coronary angioplasty

Percutaneous transluminal coronary angioplasty (PTCA) failed in 29 of 1,150 patients (2.5%) after successful passage of the guide wire. The reasons for failure were inability to pass the lesion with a balloon in 28 patients and inability to dilate the lesion in 1 patient. In these patients (15 stenoses and 14 chronic occlusions) rotational ablation was performed. We were able to pass the burr through the lesion in all of them, resulting in a reduction of diameter stenosis from 87 +/- 15 to 51 +/- 18%. Rotational ablation alone was initially successful (stenoses reduction > 20% and residual stenoses < 50%) in 15 of 29 (52%) patients. Additional PTCA was performed in 21 of 29 (72%) patients, in 8 to optimize the initially successful result and in 13 because the outcome was unsatisfactory. After dilatation the diameter stenosis was reduced to 41 +/- 14% immediately after the procedure and to 36 +/- 13% at 24 hr control. Overall success was achieved in 21 of 29 (72%) patients immediately after the procedure and in 26 of 29 (90%) patients at 24 hr control. No acute major complications occurred. We conclude that rotational ablation can be used as a safe and effective alternative when PTCA is not successful.