Feasibility and diagnostic accuracy of a low radiation exposure protocol for prospective ECG-triggering coronary MDCT angiography.

AIM: To compare the feasibility, accuracy, and effective radiation dose (ED) of multidetector computed tomography (MDCT) in the detection of coronary artery disease using a combined ED-saving strategy including prospective electrocardiogram (ECG) triggering with a short x-ray window and a body mass index (BMI)-adapted imaging protocol using adaptive statistical iterative reconstruction (ASIR; group 1), in comparison with a prospective ECG triggering strategy alone (group 2). MATERIALS AND METHODS: One hundred and seventy patients scheduled for invasive coronary angiography (ICA) were evaluated. Fourteen patients were not eligible for MDCT. The remaining 156 patients were randomized to group 1 (78 patients) and group 2 (78 patients). Eight and 11 patients in groups 1 and 2, respectively, were excluded after randomization because the patients' heart rates were >65 beats/min. MDCT images were assessed for feasibility, signal-to-noise ration (SNR), and contrast-to-noise ratio (CNR), accuracy in detection of coronary stenoses >50% versus ICA and for ED. RESULTS: The feasibility, SNR, CNR, accuracy in a segment-based and patient-based model were similar in both groups (97 versus 95%, 14.5 ± 3.9 versus 14.2 ± 4.1, 16 ± 4.6 versus 16.5 ± 4.4, 95 versus 94% and 97 versus 99%, respectively). The ED in group 1 was 72% lower than in group 2 (2.1 ± 1.2 versus 7.5 ± 1.8 mSv, respectively; p<0.01). CONCLUSIONS: The use of a multi-parametric ED saving protocol results in a significant reduction in ED without a negative impact on accuracy.

Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy.

BACKGROUND: Percutaneous coronary interventions (PCI) in calcified coronary artery lesions are associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using calcium modifying techniques such as Rotational Atherectomy (RA) or Intravascular Lithotripsy (IVL) has been advocated. Studies comparing these technologies are lacking. We aimed to compare in-stent pressure gradients, evaluated by vessel fractional flow reserve (vFFR), in calcific lesions treated using either RA or IVL. METHODS: Patients undergoing either RA- or IVL-assisted PCI from two European centers were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post-PCI in-stent pressure gradients calculated by vFFR (vFFRgrad). Secondary outcomes included the proportion of patients with complete functional revascularization defined as distal vFFR post-PCI (vFFRpost) ≥ 0.90. RESULTS: From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0.65 ± 0.13 RA and 0.67 ± 0.11 IVL). After PCI, in-stent pressure gradients were significantly lower in the IVL group (0.032 ± 0.026 vs 0.043 ± 0.026 in the RA group, p = 0.024). The proportions of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; p = 0.669). CONCLUSIONS: Calcific lesions preparation with IVL is effective and resulted in lower in-stent pressure gradients compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL.

Quantification of calcium burden by coronary CT angiography compared to optical coherence tomography.

Coronary artery calcifications (CAC) are frequently observed in patients referred for coronary CT angiography (CTA). Calcification volume (in mm3) can accurately be assessed during catheterization by optical coherence tomography (OCT). The aim of the present study was to investigate the accuracy of CTA-derived assessment of calcification volume as compared with OCT. 66 calcified plaques (32 vessels) from 31 patients undergoing OCT-guided PCI with coronary CT acquired as a standard of care were included. Coronary CT and OCT images were matched using fiduciary points. Calcified plaques were reconstructed in three dimensions to calculate calcium volume. A Passing-Bablok regression analysis and the Bland-Altman method were used to assess the agreement between imaging modalities. Twenty-seven left anterior descending arteries and 5 right coronary arteries were analyzed. Median calcium volume by CTA and OCT were 18.23 mm3 [IQR 8.09, 36.48] and 10.03 mm3 [IQR 3.6, 22.88] respectively; the Passing-Bablok analysis showed a proportional without a systematic difference (Coefficient A 0.08, 95% CI - 1.37 to 1.21, Coefficient B 1.61, 95% CI 1.45 to 1.84) and the mean difference was 9.69 mm3 (LOA - 10.2 to 29.6 mm3). No differences were observed for minimal lumen area (Coefficient A 0.07, 95% CI - 0.46 to 0.15, Coefficient B 0.85, 95% CI 0.64 to 1.2). CTA volumetric calcium evaluation overestimates calcium volume by 60% compared to OCT. This may allow for an appropriate interpretation of calcific burden in the non-invasive setting. Even in presence of calcific plaques, a good agreement in the MLA assessment was found. Coronary CT may emerge as a tool to quantify calcium burden for invasive procedural planning.

In vivo human atherosclerotic plaque recognition by laser-excited fluorescence spectroscopy.

Arterial wall perforation and chronic restenosis represent important factors limiting the clinical application of laser angioplasty. Discrimination of normal and atherosclerotic vessels by laser-excited fluorescence spectroscopy may offer a means of targeting plaque ablation, thereby reducing the frequency of restenosis and transmural perforation. In this study, with use of a 325 nm low power helium-cadmium laser, in vivo endogenous surface fluorescence was excited through a flexible 200 microns optical fiber within a 0.018 in. (0.046 cm) guide wire in contact with the intima of 268 vascular interrogation sites from 48 patients either during open heart surgery or during percutaneous catheterization procedures. Fluorescence spectra could be recorded in all patients in bloodless and blood-filled arteries. Endogenous surface fluorescence was analyzed measuring peak intensity, peak position and shape index of the spectra. Compared with normal wall, noncalcified and calcified coronary atheroma showed a 42% (p less than 0.001) and a 58% (p less than 0.001) decrease of peak intensity, and higher shape index (p less than 0.001 and p less than 0.01, respectively). In addition, peak position was shifted to longer wavelengths for noncalcified coronary atheroma (p less than 0.001). Compared with normal aorta sites, aortic plaques demonstrated a 46% decrease of peak intensity, longer peak position wavelengths (p less than 0.05) and a higher shape index (p less than 0.001). Using an atheroma detection algorithm, prospective analysis of aorta and coronary spectra showed a specificity of 100% for identifying normal sites and a sensitivity of 73% for recognizing atherosclerotic sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon expandable stent implantation in stenotic right heart valved conduits.

Although valved conduits have been used successfully in severe forms of right ventricular-pulmonary artery discontinuity, progressive valved conduit stenosis is an important clinical problem. To determine the feasibility of reducing right heart valved conduit stenosis with a balloon expandable stent, a baboon model was used, in which the pulmonary artery was ligated and a right ventricular to pulmonary artery 14 mm bioprosthetic Dacron valved conduit implanted. In five baboons, at an average of 40 months after valved conduit implantation, fibrointimal stenosis at the valve site resulted in narrowing and a mean transconduit pressure gradient of 49 mm Hg (range 33 to 65). A tubular slotted steel stent (1.2 cm long) was deployed within the valved conduit after inflation of an 8 to 15 mm diameter balloon catheter that was introduced through the femoral vein. A stent was delivered to all valved conduits; however, in two baboons, balloon undersizing resulted in stent dislodgment. In the remaining three baboons, the transconduit gradient was reduced by 59% (49 to 20 mm Hg) and right ventricular systolic pressure decreased acutely by 35% (77 to 50 mm Hg). It is concluded that stent deployment is feasible in right ventricular to pulmonary artery stenotic valved conduits and may result in significant hemodynamic improvement. However, successful stent delivery is critically dependent on the proper selection of stent length and balloon diameter.

Ultra-low-dose CT for left atrium and pulmonary veins imaging using new model-based iterative reconstruction algorithm.

AIMS: To evaluate the feasibility of ultra-low-dose CT for left atrium and pulmonary veins using new model-based iterative reconstruction (MBIR) algorithm. METHODS AND RESULTS: Two hundred patients scheduled for catheter ablation were randomized into two groups: Group 1 (100 patients, Multidetector row CT (MDCT) with MBIR, no ECG triggering, tube voltage and tube current of 100 kV and 60 mA, respectively) and Group 2 [100 patients, MDCT with adaptive statistical iterative reconstruction algorithm (ASIR), no ECG triggering, and kV and mA tailored on patient BMI]. Image quality, CT attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) of left atrium (LA) and pulmonary veins, and effective dose (ED) were evaluated for each exam and compared between two groups.No significant differences between groups in terms of population characteristics, cardiovascular risk factors, anatomical features, prevalence of persistent atrial fibrillation and image quality score. Statistically significant differences were found between Group 1 and Group 2 in mean attenuation, SNR, and CNR of LA. Significantly, lower values of noise were found in Group 1 versus Group 2. Group 1 showed a significantly lower mean ED in comparison with Group 2 (0.41 ± 0.04 versus 4.17 ± 2.7 mSv). CONCLUSION: The CT for LA and pulmonary veins imaging using MBIR is feasible and allows examinations with very low-radiation exposure without loss of image quality.

Extent and distribution of in-stent intimal hyperplasia and edge effect in a non-radiation stent population.

Intimal hyperplasia within the body of the stent is the primary mechanism for in-stent restenosis; however, stent edge restenosis has been described after brachytherapy. Our current understanding about the magnitude of in vivo intimal hyperplasia and edge restenosis is limited to data obtained primarily from select, symptomatic patients requiring repeat angiography. The purpose of this study was to determine the extent and distribution of intimal hyperplasia both within the stent and along the stent edge in relatively nonselect, asymptomatic patients scheduled for 6-month intravascular ultrasound (IVUS) as part of a multicenter trial: Heparin Infusion Prior to Stenting. Planar IVUS measurements 1 mm apart were obtained throughout the stent and over a length of 10 mm proximal and distal to the stent at index and follow-up. Of the 179 patients enrolled, 140 returned for repeat angiography and IVUS at 6.4 +/- 1.9 months and had IVUS images adequate for analysis. Patients had 1.2 +/- 0.6 Palmaz-Schatz stents per vessel. There was a wide individual variation of intimal hyperplasia distribution within the stent and no mean predilection for any location. At 6 months, intimal hyperplasia occupied 29.3 +/- 16.2% of the stent volume on average. Lumen loss within 2 mm of the stent edge was due primarily to intimal proliferation. Beyond 2 mm, negative remodeling contributed more to lumen loss. Gender, age, vessel location, index plaque burden, hypercholesterolemia, diabetes, and tobacco did not predict luminal narrowing at the stent edges, but diabetes, unstable angina at presentation, and lesion length were predictive of in-stent intimal hyperplasia. In a non-radiation stent population, 29% of the stent volume is filled with intimal hyperplasia at 6 months. Lumen loss at the stent edge is due primarily to intimal proliferation.

Vascular stent deployment in vein bypass grafts: observations in an animal model.

BACKGROUND: An important cause of vein graft failure is anastomotic stenosis caused by myointimal hyperplasia. Intravascular stents may allow balloon dilation of these hyperplastic lesions, thereby increasing secondary graft patency. METHODS: To evaluate intravascular stent deployment in vein grafts, we implanted 26 stents across the anastomotic sites of reversed vein grafts in 13 sheep. Stent deployment was evaluated immediately and at 3, 8, and 24 weeks by arteriography, light microscopy, and scanning electron microscopy. In a second animal cohort, stent-arterial wall contact after deployment was evaluated with intravascular ultrasonography (IVUS). Stents were imaged with IVUS after partial (n = 5) and complete (n = 5) expansion in 10 sheep carotid arteries. RESULTS: Stents were deployed across vascular anastomoses without immediate thrombosis. Partial neointimal coverage occurred after 3 and 8 weeks, with complete coverage by 24 weeks. Complications included distal migration (n = 3), arteriographic stenosis (n = 2), and late graft occlusion (n = 2). Incomplete stent-vessel wall contact at deployment was observed in the stents with complications. IVUS accurately showed stent expansion and the degree of stent-vessel wall contact. CONCLUSIONS: Stents can be deployed in vein grafts with the expectation of neointimal coverage and maintenance of graft patency. IVUS may prove important in guiding optimal stent deployment by providing an assessment of stent-vessel wall contact.

"Thinning-down phenomenon" and vasomotor adaptability of the inferior epigastric artery graft.

We report a case of diffuse thinning of an inferior epigastric artery early after its implantation as a coronary free graft. This phenomenon showed reversibility at the 20-month angiographic follow-up in response to progression of the proximal lesion in the recipient coronary artery. Graft vasodilation in response to atrial pacing and nitroglycerin infusion at late angiography confirmed the vasomotor adaptability of this arterial conduit.

An in vivo feasibility study of intravascular ultrasound imaging.

Increasingly complex vascular reconstructions and emerging endovascular therapeutic modalities have stimulated the need for improved vascular imaging. To determine the feasibility of in vivo intravascular ultrasound, a miniature probe 1 mm in diameter with a 25 MHz center frequency was used to obtain two-dimensional, 360-degree cross-sectional images. In sheep, 14 superficial femoral arteries were imaged at different sites, and a portion of each vessel was resected for immediate in vitro imaging and histologic examination. In vivo images clearly showed the intima, media, and adventitia of the vessel wall as well as the lumen-intima and media-adventitia interfaces. There was a significant correlation in measured lumen area between resected artery ultrasound images and histologic sections. We conclude that intravascular ultrasound can produce high-resolution dynamic images that demonstrate vessel wall architecture and allow precise calculation of lumen area.

Anomalous origin of the left anterior descending and circumflex coronary arteries by two separate ostia from the right sinus of Valsalva.

We report a case of absence of the left main coronary artery with the left anterior descending and circumflex coronary arteries arising by two separate ostia from the right sinus of Valsalva in a patient without other congenital cardiovascular malformations. The clinical and angiographic features of this exceedingly rare anomaly are described with a brief review of previously documented cases.

Emergency stenting of totally occluded left main coronary artery in acute myocardial infarction.

We report a case of emergency stenting for acute occlusion of the left main coronary artery in the setting of acute myocardial infarction. Although stent implantation allowed prompt revascularization and successful immediate management of this life-threatening condition, subacute stent thrombosis occurred, requiring re-PTCA followed by surgical revascularization. This case suggests that stenting of an acutely occluded left main coronary artery may be a life-saving procedure but should only be used as a bridge to surgery rather than a definitive treatment modality.

Contemporary antithrombotic strategies in patients undergoing coronary stent implantation.

The number of annual stenting procedures has been increasing at a rapid pace since coronary stents were first used in clinical practice just over a decade ago. Subacute stent thrombosis, which usually has serious clinical consequences, plagued the stent early experience despite intense anticoagulation therapy. The reduction of stent thrombosis was among the factors that contributed to stent growth and widespread acceptance in recent years. This was the result of improved implantation techniques, advances in adjunctive pharmacotherapy and evolution in stent designs, delivery systems and non-thrombogenic coatings. However, novel designs and materials customized for particular lesion types and newer anti-restenotic treatments could influence stent thrombogenicity. Intravascular brachytherapy and drug-eluting stents have been shown to reduce the incidence of in-stent restenosis preventing cellular proliferation. However, by interfering with the re-endothelization process they may also increase the risk of stent thrombosis. To prevent a recrudescence of this feared complication, future research direction must focus on the hemocompatibility aspects of new technologies, along with further refinement of stent-deployment techniques and antithrombotic strategies.

Patent ductus arteriosus closure using the new Amplatzer Duct Occluder. Preliminary results and review of the literature.

BACKGROUND: Patent ductus arteriosus (PDA) is the second most common congenital heart disease. A large number of surgical and transcatheter techniques for the interruption or closure of PDA has been reported. The aim of this study was to assess the immediate and short-term results of transcatheter closure of PDA using the new, self-expandable, self-centering, and repositionable Amplatzer Duct Occluder device. METHODS: We attempted occlusion of PDA with the Amplatzer Duct Occluder in seven consecutive patients, one child and six adults, four females and three males, between September 1999 and January 30th 2000. All PDAs but one were approached from the femoral venous site; the Amplatzer Duct Occluder size was selected in order to be 2 mm larger than the duct's diameter at its narrowest site and the mean PDA diameter was 5.4+/-2.5 mm (range 3-9). All patients underwent physical examination, chest X-ray and echocardiography within 48 hours and on first and third month after PDA occlusion. RESULTS: Four patients had a megaphone type (type A), and three had an elongated, conical type (type E) PDA. Four patients had immediate, complete angiographic closure of the ductus 10 minutes after the procedure, one had a trace shunt and two had small shunts which all disappeared within 48 hours. The average fluoroscopy time and procedural time were 34.4+/-10.6 min (range 21-50) and 105+/-38.9 min (range 75-190) respectively. There were no complications at follow-up. CONCLUSIONS: Transcatheter closure of PDA using the new Amplatzer Duct Occluder is an easy and effective technique. Moreover it is safe even in the presence of wide PDAs.

[Recurrent ventricular fibrillation in acute myocardial infarct treated successfully by coronary angioplasty: a clinical case in favor of the hypothesis of the arrhythmogenicity of the coronary thrombus?]. / Fibrillazione ventricolare recidivante nell'infarto miocardico acuto trattata con successo mediante angioplastica coronarica: un caso clinico a favore dell'ipotesi di aritmogenicità del trombo coronarico?

We describe a patient with acute myocardial infarction due to thrombotic occlusion of the left anterior descending coronary artery. Following thrombolytic therapy, five episodes of ventricular fibrillation recurred despite the absence of profibrillatory factors other than myocardial ischemia. Because of thrombolysis failure, rescue angioplasty associated with coronary stent implantation was performed. After successful mechanical artery recanalization, no recurrences of the malignant arrhythmia were observed. This case supports the concept, recently demonstrated in animals, that the process of intracoronary thrombosis itself may have arrhythmogenic effects above and beyond the impact of myocardial ischemia induced by coronary occlusion per se.

Hemofiltration in the prevention of radiocontrast agent induced nephropathy.

AIM: The aim of the study was to investigate the role of hemofiltration in preventing contrast nephropathy in patients with renal failure. METHODS: We randomized 114 renal failure patients undergoing percutaneous coronary interventions (PCI) to either peri-procedural hemofiltration or saline hydration. RESULTS: Contrast nephropathy occurred in 5% of hemofiltration-treated patients and in 50% in controls (P<0.01). In-hospital event rate as well as in-hospital and 1-year mortality rates were lower in patients treated with hemofiltration. CONCLUSION: In patients with renal failure undergoing PCI, peri-procedural hemofiltration is effective for the prevention of contrast nephropathy, and is associated with improved in-hospital and long-term outcome.

[Recurrent restenosis after angioplasty of anomalous right coronary artery]. / Ristenosi recidivante dopo angioplastica di una coronaria destra anomala.

An anomalous right coronary artery underwent successful percutaneous transluminal coronary angioplasty (PTCA) but exercise-induced myocardial ischemia persisted. Moreover, recurrent restenosis were angiographically documented and treated by repeat PTCA. Post-PTCA large atheroma burden not appreciable by angiography, high take-off, and tangential origin of the vessel from the aorta may be some of the mechanisms involved in myocardial ischemia persistence and restenosis of the vessel.

Cinefluoroscopic identification of Björk-Shiley prosthetic heart valves.

Numerous mechanical prostheses are currently utilized for heart valve replacement. Fluoroscopy is a useful technique to identify prosthetic valves, to evaluate their function and to follow-up the patients' condition. Scattered and contrasting data, however, have been reported about the radiographic appearance of Björk-Shiley heart valves. This study shows that each Björk-Shiley valve model has characteristic radiographic features that can be readily determined by fluoroscopic evaluation, leading to easy and accurate non-invasive identification.

[Intravenous ultrasonography as a method for imaging the morphoanatomical effects of coronary angioplasty]. / L'ultrasonografia intravascolare quale metodica di indagine degli effetti morfoanatomici dell'angioplastica coronarica.

Despite the therapeutic success of percutaneous transluminal coronary angioplasty (PTCA), the mechanisms by which PTCA increase vessel luminal size remain uncertain. To better understand the transmural morphologic changes associated with PTCA of stenosed coronary arteries, we studied with a high-frequency intravascular ultrasound catheter 18 coronary artery segments in 18 patients following balloon angioplasty. High-quality cross-sectional images were obtained from 15 coronary sites without complications in all patients. Two distinctive morphologic features following balloon angioplasty were appreciated by intravascular ultrasound imaging. The first pattern, observed in 10 cases (67%), consisted of a stretched plaque without any evidence of dissection. The second pattern, found in 5 cases (33%), demonstrated a dissection of the plaque ranging from a radial tear with separation of the 2 ends of the plaque to an extensive dissection which, in 1 case, encompassed the entire circumference of the artery. Although angiography showed a good post-angioplasty result in all cases, intravascular ultrasound evidenced a large amount of residual atheroma occupying the artery cross-sectional area. In addition, this imaging modality revealed more often than angiography the presence of calcification and dissection. These data demonstrate that PTCA creates different morphologic patterns which are related to the mechanisms of lumen enlargement and that the coronary artery anatomy after dilatation is much more complex than that observed with angiography. This study confirms that intravascular ultrasound is a feasible and safe imaging modality which provides new valuable insight into the mechanisms by which angioplasty improves vessel patency.