Biomedical subjects

John C Messenger

Publications and source records attributed to John C Messenger.

10 recordsLinked to original sources

PubMed2006

Rotational angiography (RA) and three-dimensional imaging (3-DRA): an available clinical tool.

Being able to accurately choose an optimal view for stent positioning, non foreshortened length and to avoid side branches is imperative during therapeutic procedures. Traditional imaging limitations may include the selection of an incorrectly sized stent, inaccurate placement, and/or the need for additional stents. With the use of newer acquisition techniques and three-dimensional (3-D) modeling/reconstructions this can be minimized. We present a case in which with the assistance of 3-D and its computer derived optimal view, and optimal length, a significant amount of vessel foreshortening was eliminated therefore improving the procedural outcome.

Angioplasty, Balloon, Coronary↗

PubMed2006

Prevalence, predictors, and outcomes of premature discontinuation of thienopyridine therapy after drug-eluting stent placement: results from the PREMIER registry.

BACKGROUND: Although drug-eluting stents (DES) significantly reduce restenosis, they require 3 to 6 months of thienopyridine therapy to prevent stent thrombosis. The rate and consequences of prematurely discontinuing thienopyridine therapy after DES placement for acute myocardial infarction (MI) are unknown. METHODS AND RESULTS: We used prospectively collected data from a 19-center study of MI patients to examine the prevalence and predictors of thienopyridine discontinuation 30 days after DES treatment. We then compared the mortality and cardiac hospitalization rates for the next 11 months between those who stopped and those who continued thienopyridine therapy. Among 500 DES-treated MI patients who were discharged on thienopyridine therapy, 68 (13.6%) stopped therapy within 30 days. Those who stopped were older, less likely to have completed high school or be married, more likely to avoid health care because of cost, and more likely to have had preexisting cardiovascular disease or anemia at presentation. They were also less likely to have received discharge instructions about their medications or a cardiac rehabilitation referral. Patients who stopped thienopyridine therapy by 30 days were more likely to die during the next 11 months (7.5% versus 0.7%, P<0.0001; adjusted hazard ratio=9.0; 95% confidence interval=1.3 to 60.6) and to be rehospitalized (23% versus 14%, P=0.08; adjusted hazard ratio=1.5; 95% confidence interval=0.78 to 3.0). CONCLUSIONS: Almost 1 in 7 MI patients who received a DES were no longer taking thienopyridines by 30 days. Prematurely stopping thienopyridine therapy was strongly associated with subsequent mortality. Strategies to improve the use of thienopyridines are needed to optimize the outcomes of MI patients treated with DES.

Aged↗

PubMed2005

Angiographic views used for percutaneous coronary interventions: a three-dimensional analysis of physician-determined vs. computer-generated views.

The goal of this study was to determine the severity of vessel foreshortening in standard angiographic views used during percutaneous coronary intervention (PCI). Coronary angiography is limited by its two-dimensional (2D) representation of three-dimensional (3D) structures. Vessel foreshortening in angiographic images may cause errors in the assessment of lesions or the selection and placement of stents. To date, no technique has existed to quantify these 2D limitations or the performance of physicians in selecting angiographic views. Stent deployment was performed in 156 vessel segments in 149 patients. Using 3D reconstruction models of each patient's coronary tree, vessel foreshortening was measured in the actual working view used for stent deployment. A computer-generated optimal view was then identified for each vessel segment and compared to the working view. Vessel foreshortening ranged from 0 to 50% in the 156 working views used for stent deployment and varied by coronary artery and by vessel segment within each artery. In general, views of the mid circumflex artery were the most foreshortened and views of the right coronary artery were the least foreshortened. Expert-recommended views frequently resulted in more foreshortening than computer-generated optimal views, which had only 0.5% +/- 1.2% foreshortening with < 2% overlap for the same 156 segments. Optimal views differed from the operator-selected working views by > or = 10 degrees in over 90% of vessels and frequently occurred in entirely different imaging quadrants. Vessel foreshortening occurs frequently in standard angiographic projections during stent deployment. If unrecognized by the operator, vessel foreshortening may result in suboptimal clinical results. Modifications to expert-recommended views using 3D reconstruction may improve visualization and the accuracy of stent deployment. These results highlight the limitations of 2D angiography and support the development of real-time 3D techniques to improve visualization during PCI.

Adult↗

PubMed2005

Coronary sinus lead extraction in the era of cardiac resynchronization therapy: single center experience.

As the number of coronary sinus (CS) lead implantations for cardiac resynchronization therapy increases so will the need for extraction of these leads. The safety of extraction of leads from the branches of the CS has not been reported. We reviewed our database of patients undergoing pacemaker lead extraction from January 2002 through February 2004 at our institution. Of 149 patients referred for lead extraction, 14 (9%) had a biventricular device. The indications for lead extraction were infection, lead malfunction, and exit block. The duration of CS lead implants ranged between 2 and 43 months (mean 17 months). All 14 CS leads were removed successfully using nonsurgical lead extraction techniques. Three leads that were in place the longest (> or =27 months) were removed via the femoral vein approach due to fibrous attachment of the CS lead body to the other pacemaker leads. The leads were structurally intact and without any significant fibrosis of their tips upon visual inspection. There were no major complications of CS laceration, hypotension, pericardial effusion, or excessive blood loss associated with any of the extraction procedures. CS leads were removed safely, successfully and with relative ease based on our experience in this small cohort of patients.

Aged↗

PubMed2004

Randomized study of the safety and clinical utility of rotational angiography versus standard angiography in the diagnosis of coronary artery disease.

This study evaluates the safety and clinical utility of rotational angiography in the diagnosis of coronary artery disease. High-speed rotational angiography is a newly available angiographic modality that gives a dynamic multiple-angle perspective of the coronary tree during a single contrast injection. We prospectively randomized 56 patients referred for diagnostic coronary angiography to either standard or rotational angiography. Contrast and radiation utilization were compared between the two groups. The number of additional cine acquisitions needed was used to determine adequacy of the diagnostic study protocol. Rotational angiography was successfully completed in all subjects. There was a 33% reduction in contrast utilization in the rotational group as compared to the standard group (35.6 +/- 12.6 vs. 52.8 +/- 10.7 ml, respectively; P < 0.0001). Additionally, there was a 28% reduction in total radiation exposure in the rotational group as compared to the standard group (39.0 +/- 18.5 vs. 53.9 +/- 23.4 Gycm(2), respectively; P = 0.01). Total whole-body radiation exposure to the primary operator was 144 mrem with rotational angiography and 170 mrem with standard angiography. Procedure time tended to be shorter for rotational angiography (353.9 +/- 146.7 vs. 396.8 +/- 165.8 s; P = 0.3). Rotational coronary angiography can be rapidly performed in any patient and provides a significant reduction in contrast and radiation utilization while at the same time providing adequate angiographic data to complement or replace standard coronary angiography in the evaluation of coronary artery disease.

Adult↗

PubMed2004

Three-dimensional vascular angiography.

Traditional angiography of the vasculature is limited by its 2-dimensional projection of complex 3-dimensional structures and the consequent imaging artifacts that interfere with visualization. During the last 10 years, technologies capable of minimizing the shortcomings of traditional angiography have been developed and are now in clinical use. Rotational angiography and 3-dimensional imaging are 2 of these powerful tools and, together, represent a major advance in the angiographic diagnosis and treatment of patients with coronary, cerebral, and peripheral vascular disease.

Cardiovascular Diseases↗

PubMed2004

Three-dimensional analysis of in vivo coronary stent--coronary artery interactions.

Stent implantation results in important three-dimensional (3D) changes in arterial geometry which may be associated with adverse events. Previous attempts to quantify these 3D changes have been limited by two-dimensional techniques. Using a 3D reconstruction technique, vessel curvatures at end-diastole (ED) and end-systole (ES) were measured before and after stent placement of 100 stents (3 stent cell designs, 6 stent types). After stenting, the mean curvature at ED and ES decreased by 22 and 21%, respectively, and represents a straightening effect on the treated vessel. This effect was proportional to the amount of baseline curvature as high vessel curvature predicted more profound vessel straightening. When analyzed by stent cell design, closed-cell stents resulted in more vessel straightening than other designs (open cell or modified slotted tubes). Stent implantation resulted in the transmission of shape changes to stent ends and generated hinge points or buckling. Stent implantation creates 3D changes in arterial geometry which can be quantified using a 3D reconstruction technique.

Blood Vessel Prosthesis Implantation↗

PubMed2002

Four-dimensional analysis of cyclic changes in coronary artery shape.

The objective of this study was to derive a method for quantifying the dynamic geometry of coronary arteries. Coronary artery geometry plays an important role in atherosclerosis. Coronary artery geometry also influences the performance of coronary interventions. Conversely, implantation of stents may alter coronary artery geometry. Clinical tools to define vessel shape have not been readily available. Using a Frenet-Serret curvature analysis applied to 3D reconstruction data derived from standard coronary angiograms, 21 coronary arteries were analyzed at end-diastole (ED) and end-systole (ES). Vessels were divided anatomically: type 1 consisted of vessels lying in the AV groove (left circumflex, right coronary) and type 2 consisted of vessels overlying actively contracting myocardium (left anterior descending, diagonal, obtuse marginal, right ventricular marginal, posterior descending, posterolateral). Vessel segments were analyzed by assessing the changes in curvature, torsion, and discrete flexion points (FPs), areas of systolic bending in the arterial contour. The curvature from ED to ES of type 1 vessels was unchanged (-0.02 +/- 0.03 cm(-1)), while the curvature change of type 2 vessels showed a 38% increase (0.33 +/- 0.04 cm(-1); P < 0.001). Type 1 vessels had fewer FPs per vessel than type 2 vessels (0.38 +/- 0.18 and 2.40 +/- 0.23 FP/vessel, respectively; P < 0.001). FPs were more common in distal segments and branch vessels. A method to quantify cyclic changes in coronary artery shape was applied to 3D data sets derived from standard coronary angiograms. Coronary arteries undergo a cyclic change in shape resulting in changes in overall curvature as well as formation of discrete flexion points. These changes in vessel shape are asymmetrically distributed in coronary arteries.

Coronary Angiography↗

PubMed2002

Optimal deployment of third-generation stents: an intravascular ultrasound assessment.

Third-generation intracoronary stents allow deployment at higher pressures, possibly obviating the need for high-pressure postdilations and also possibly reducing restenosis. This study evaluated the ability of the Tristar Coronary Stent System to produce optimal stent deployment as measured by intravascular ultrasound (IVUS) and quantitative coronary angiography in 46 patients. Optimal stent deployment was defined as minimal luminal area > 80% of the average of the proximal and distal reference luminal areas. After initial deployment, 74.5% of stents met criteria for optimal stent deployment by IVUS, with an average stent expansion ratio of 89.6%. Ten stents (18.2%) were postdilated. Four patients (8.7%) had a major adverse cardiac event, one patient died, one patient had a myocardial infarction, and two patients had target vessel revascularization at 6 months. The Tristar stent system produces optimal deployment without the need for routine postdilation and results in optimal clinical outcomes.

Adult↗

PubMed2002

Quantitative analysis of reconstructed 3-D coronary arterial tree and intracoronary devices.

Traditional quantitative coronary angiography is performed on two-dimensional (2-D) projection views. These views are chosen by the angiographer to minimize vessel overlap and foreshortening. With 2-D projection views that are acquired in this nonstandardized fashion, however, there is no way to know or estimate how much error occurs in the QCA process. Furthermore, coronary arteries possess a curvilinear shape and undergo a cyclical deformation due to their attachment to the myocardium. Therefore, it is necessary to obtain three-dimensional (3-D) information to best describe and quantify the dynamic curvilinear nature of the human coronary artery. Using a patient-specific 3-D coronary reconstruction algorithm and routine angiographic images, a new technique is proposed to describe: 1) the curvilinear nature of 3-D coronary arteries and intracoronary devices; 2) the magnitude of the arterial deformation caused by intracoronary devices and due to heart motion; and 3) optimal view(s) with respect to the desired "pathway" for delivering intracoronary devices.

Algorithms↗