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ABSTRACT: A method for prospective motion correction of X-ray imaging of the heart is presented. A 3D+t coronary model is reconstructed from a biplane coronary angiogram obtained during free breathing. The deformation field is parameterized by cardiac and respiratory phase, which enables the estimation of the state of the arteries at any phase of the cardiac-respiratory cycle. The motion of the three-dimensional (3-D) coronary model is projected onto the image planes and used to compute a dewarping function for motion correcting the images. The use of a 3-D coronary model facilitates motion correction of images acquired with the X-ray system at arbitrary orientations. The performance of the algorithm was measured by tracking the motion of selected left coronary landmarks using a template matching cross-correlation. In three patients, we motion corrected the same images used to construct their 3D+t coronary model. In this best case scenario, the algorithm reduced the motion of the landmarks by 84%-85%, from mean RMS displacements of 12.8-14.6 pixels to 2.1-2.2 pixels. Prospective motion correction was tested in five patients by building the coronary model from one dataset, and correcting a second dataset. The patient's cardiac and respiratory phase are monitored and used to calculate the appropriate correction parameters. The results showed a 48%-63% reduction in the motion of the landmarks, from a mean RMS displacement of 11.5-13.6 pixels to 4.4-7.1 pixels.
IEEE Transactions on Medical Imaging 05/2005; · 3.64 Impact Factor
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E Nikolsky,
L Gruberg,
E Rosenblatt,
E Grenadier,
M Boulos,
Z Bernstein,
A Huber,
R Gitman,
R Bar-Deroma,
W Markiewicz, R Beyar
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ABSTRACT: Percutaneous coronary intervention of chronic total occlusions (CTO) is associated with a significantly higher incidence of reocclusion and restenosis compared with non-total occlusions. Randomized and observational trials have demonstrated the effectiveness of intracoronary brachytherapy (ICBT) for the prevention of recurrent in-stent restenosis. However, limited data are available on the effectiveness of ICBT in patients with totally occluded in-stent restenosis. The authors assessed the long-term outcome of patients treated with intracoronary gamma radiation for totally occluded in-stent restenotic lesions. Percutaneous coronary intervention and subsequent catheter-based irradiation with iridium-192 was performed in 100 patients (103 vessels) with diffuse in-stent restenosis. At baseline, CTO of the target vessel at the site of the stent was present in 15 vessels (14.5%). Follow-up data were collected during follow-up visits and from telephone interviews. Repeat coronary angiography was performed in symptomatic patients with clinical restenosis. Clinical and angiographic characteristics were similar between the two groups, although there was a trend towards more unstable angina at the index procedure in CTO patients (66.7% versus 41.4%; p = 0.12) compared with patients without non-total occlusions. A higher percentage of patients (53.3%) with CTO required longer radiation sources (14 seeds, covering a length of 55 mm), compared with 23.9% of patients with non-total occlusion (p = 0.04). With a mean follow-up period of 47.5 +/- 24.0 months, major adverse cardiac events (MACE) were observed in 10 of 15 patients (66.7%) with CTO compared with 25 out of 88 patients (28.4%) without CTO (p = 0.009). According to multivariate analysis, total occlusion of the target vessel at baseline was the single independent predictor of MACE at one-year follow-up (relative risk 16.2, 95% confidence interval 4.2-62.9; p < 0.0001). This study shows that the use of gamma radiation for the prevention of recurrence of in-stent restenosis in patients with CTO does not seem to be as effective as in patients with non-total occlusions. Furthermore, CTO was an independent predictor of worse outcome at long-term follow-up in this study.
International Journal of Cardiovascular Interventions 01/2004; 6(1):33-8.
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European Heart Journal 12/2001; 22(22):2054-7. · 10.48 Impact Factor
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The Journal of invasive cardiology 09/2001; 13(8):582-3. · 1.84 Impact Factor
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European Heart Journal 08/2001; 22(14):1183-97. · 10.48 Impact Factor
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ABSTRACT: To determine whether pericardial liquid pressure accurately measures pericardial constraint, we developed a technique in which a catheter was positioned perpendicular to the epicardial surface. This device, which occupies little or no pericardial space, couples the thin film of liquid to a transducer. In six open-chest dogs, we also measured left ventricular (LV) end-diastolic pressure (LVEDP) and anteroposterior and septum-to-free wall diameters. LVEDP was raised incrementally to approximately 25 mmHg by saline infusion. With the use of the product of the two diameters as an index of area (A(LV)), LVEDP-A(LV) relationships were obtained with the pericardium closed and again after the pericardium had been widely opened to obtain the isovolumic difference in LVEDP (DeltaLVEDP). In all dogs, the technique yielded values of pericardial pressure equal to DeltaLVEDP as well as equal to that measured using a previously placed balloon transducer in the same location and at the same A(LV). We conclude that, when the pressure of the pericardial liquid is appropriately measured, it (in addition to the balloon-measured contact stress) defines the diastolic constraining effect of the pericardium. Furthermore, we suggest that earlier measurements of pericardial "liquid pressure" were low, due to an artifact of measurement.
AJP Heart and Circulatory Physiology 07/2001; 280(6):H2815-22. · 3.71 Impact Factor
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The Journal of invasive cardiology 07/2001; 13(6):453-5. · 1.84 Impact Factor
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ABSTRACT: We have demonstrated that a genetic polymorphism in the antioxidant protein haptoglobin is important in determining which patients develop restenosis after percutaneous transluminal coronary angioplasty. Knowledge of the haptoglobin phenotype may be useful in the assessment and utilization of new therapies to reduce restenosis, particularly in patients who are homozygous for the haptoglobin 2 allele.
The American Journal of Cardiology 03/2001; 87(3):330-2, A9. · 3.37 Impact Factor
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The Journal of invasive cardiology 02/2001; 13(1):9-11. · 1.84 Impact Factor
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European Heart Journal 12/2000; 21(21):1732-4. · 10.48 Impact Factor
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The Journal of invasive cardiology 08/2000; 12(7):351-3. · 1.84 Impact Factor
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ABSTRACT: Intravascular ultrasound (IVUS) has established itself as a useful tool for coronary assessment. The vast amount of data obtained by a single IVUS study renders manual analysis impractical for clinical use. A computerized method is needed to accelerate the process and eliminate user-dependency. In this study, a new algorithm is used to identify the lumen border and the media-adventitia border (the external elastic membrane). Setting an initial surface on the IVUS catheter perimeter and using active contour principles, the surface inflates until virtual force equilibrium defined by the surface geometry and image features is reached. The method extracts these features in three dimensions (3-D). Eight IVUS procedures were performed using an automatic pullback device. Using the ECG signal for synchronization, sets of images covering the entire studied region and corresponding to the same cardiac phase were sampled. Lumen and media-adventitia border contours were traced manually and compared to the automatic results obtained by the suggested method. Linear regression results for vessel area enclosed by the lumen and media-adventitia border indicate high correlation between manual vs. automatic tracings (y = 1.07 x -0.38; r = 0.98; SD = 0.112 mm(2); n = 88). These results indicate that the suggested algorithm may potentially provide a clinical tool for accurate lumen and plaque assessment.
Ultrasound in Medicine & Biology 06/2000; 26(4):527-37. · 2.29 Impact Factor
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ABSTRACT: A previous report demonstrated transient myocardial echocardiographic contrast (MEC) enhancement following high-speed rotational atherectomy (HSRA). This phenomenon was found to be correlated to the speed and duration of rotation and related to creation of cavitations. To determine other correlations and the significance of MEC, continuous echocardiographic recording was performed in 10 patients undergoing HSRA. Images were digitized and videointensity-time curves generated. Curve parameters were calculated and correlated with procedural variables, plaque mass, and side effects. Twenty-nine ablation passes in 10 patients were analyzed. Videointensity peaked 9-44 sec from initiation of ablation and decayed to a higher baseline level after each consecutive ablation. Increase in peak contrast intensity (PCI) from baseline and the percentage of the left ventricle undergoing enhancement were highest (33 +/- 31 gray level/pixel and 32% +/- 8%, mean +/- SD, respectively) after the second rotation and were not influenced by the duration of rotation. PCI, side effects, and transient left ventricular wall motion abnormalities were positively correlated with plaque mass, defined by the product of lesion length, diameter, and percent stenosis. HSRA resulted in significant myocardial echocardiographic contrast. PCI is related to ablation sequence and plaque mass. Plaque debris embolization is probably responsible for myocardial echocardiographic contrast and transient wall motion abnormalities. Cathet. Cardiovasc. Intervent. 49:39-44, 2000.
Catheterization and Cardiovascular Interventions 02/2000; 49(1):39-44. · 2.29 Impact Factor
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ABSTRACT: The three dimensional (3D) conformational changes in three patients with large anterior aneurysm in the left ventricle (LV) were examined before and two years after aneurysmectomy by using 3D Cine-computerized tomography (CT). Endocardial and epicardial tracings of 6-9 short axis images encompassing the entire LV were used to reconstruct the LV in 3D. Thickness and percent thickening were calculated using our 3D-volume element approach. A regional wall stress index (stress/pressure) was calculated from regional curvature and thickness. The analysis showed that following resection of the aneurysm the end-diastolic volume was reduced from 257+/-39 to 183+/-39 ml, end-systolic volume from 172+/-39 to 92+/-46 ml and, ejection fraction increased from 34+/-7 to 51+/-13%. The endocardial aneurysm area decreased from 19.7+/-15.9 to 10.1+/-6.5 cm2, whereas the normal zone area was minimally reduced from 87.4+/-17.6 to 79.8+/-10.8 cm2. The percent thickening of the normal zone increased significantly. It is documented here for the first time by detailed 3D analysis that the resection of the LV aneurysm reduces the aneurysmal area and LV size and improves the global and regional function of the remote normal zone. Therefore, the 3D approach can help to design better surgical technique for this complex operation.
Medical Engineering & Physics 11/1999; 21(8):547-54. · 1.62 Impact Factor
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ABSTRACT: The current explosion in coronary stent use for the treatment of coronary artery disease has helped to better define who really benefits from coronary stenting. It is clear that plain old balloon angioplasty can be at least as efficacious as stenting in certain patient groups. Patients with reference vessel diameter of < 2.5 mm, a small post-stent minimal lumen diameter, lesion length > 30 mm, diabetes mellitus and end-stage renal failure--all associated with a high incidence of diffuse in-stent restenosis--should not be stented routinely. The judicious use of stents in percutaneous revascularization will improve patient outcomes and decrease cost. The progress that has been achieved in coronary stent designs has led to many new questions, such as which patients benefit the most from stenting and whether adjunctive therapies or stent coatings will effectively prevent restenosis. Despite the advances in stent/balloon technology, antiplatelet agents, and interventional operator skill, the problems of in-stent restenosis remain. Novel therapeutic strategies for the management of severe coronary artery disease are evolving rapidly. Radiation therapy shows promise on this front. This therapy may reduce rates of restenosis by inhibiting smooth muscle proliferation and migration. However, important issues regarding the type of radiation and the matter of edge-restenosis are yet to be resolved, and the results of ongoing prospective randomized trials should provide valuable information on the efficacy of this modality. Patients with severe, non-revascularizable coronary artery disease and debilitating symptoms represent another frustrating clinical problem. PMR performed in the cardiac catheterization laboratory may improve symptoms of angina in patients with end-stage coronary artery disease. The early results are propitious. Among patients who have undergone this procedure 80-90% have improved from class IV (the most severe chest pain) to class I or II, enabling them to live relatively normal lives. Most investigators believe that PMR may be used only for those who are unsuitable candidates for percutaneous or surgical revascularization. Finally, gene therapy, by stimulating angiogenesis and improving coronary collateral development, may prove to be the most optimal treatment. Each of these strategies is currently under active investigation to confirm the results of the pilot studies, identify patient subgroups likely to respond to therapy, and determine long-term safety. Together with its challenges, the future of interventional cardiology is indeed bright.
The Israel Medical Association journal: IMAJ 10/1999; 1(2):104-11. · 1.02 Impact Factor
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ABSTRACT: We recently reported a high technical and 30-day clinical success rate among the first 100 patients treated with the tubular, serpentine design, stainless steel, balloon-expandable stent (beStent) in Israel. The present study examined the clinical results in these patients after the first year.
Seventy-eight men and 22 women were included in the study. Previous myocardial infarction, bypass surgery and percutaneous transluminal coronary angioplasty had occurred in 52%, 12% and 26% of the patients, respectively. Diabetes mellitus was present in 30 patients and hypertension in 34 patients. One hundred and forty-eight stents of 15, 25, and 35 mm lengths were used. The indications for stenting were suboptimal results (n = 85), bailout conditions (n = 10) or for the prevention of restenosis (n = 8), and lesion types were A (n = 10), B1 (n = 29), B2 (n = 20), and C (n = 44). All patients were clinically monitored with regular visits at 1, 3, 6, 9 and 12 months.
Overall, the 12-month event-free survival rate was 82%. Subacute thrombosis occurred in two patients. There were two non-cardiac deaths, one O-wave myocardial infarction, six elective bypass surgeries and 12 target lesion revascularizations. Event-free survival was significantly higher for those with lesions shorter than 15 mm than for those with lesions longer than 15 mm (90% versus 67%, P = 0.003), and for women compared with men (96% versus 78%, P = 0.02).
The initial experience with the beStent shows favorable long-term results with an overall event rate of 18% for this subset of relatively complex lesions; higher event rates were observed for longer lesions.
Coronary Artery Disease 10/1999; 10(6):421-5. · 1.24 Impact Factor
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ABSTRACT: We aimed to characterize regional geometry in relation to load in two groups of patients with hypertrophic cardiomyopathy (HCM) and right ventricular pressure overload (RVPO) in relation to a group of subjects with normal left ventricular (LV) function.
Both these diseases are associated with marked changes in LV shape and function, which have not been studied with detailed three dimensional tools.
Three dimensional (3D) tagged magnetic resonance imaging (MRI) was used to characterize the 3D geometry and regional stresses of the left ventricles in patients with HCM and RVPO. Curvatures, stresses, wall thickness, and endocardial motion were calculated from surface and volume elements.
Hearts with RVPO exhibited more circumferential and meridional flattening of the septum than normal and HCM hearts. The stress indices were lowest in the HCM hearts, compared to normal and RVPO hearts, due to the larger thicknesses. There was a more significant difference between lateral wall motion and other regional wall motions in the HCM and RVPO hearts as compared to normal hearts.
It is suggested that curvature and stress mapping by 3D tagged MRI can be used as an important clinical tool for characterizing and distinguishing between healthy and diseased hearts. The results provided here validated previous knowledge on HCM and RVPO known from planary imaging methods.
International Journal of Cardiac Imaging 09/1999; 15(4):309-21.
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ABSTRACT: This study sought to report the first-year clinical outcome with the nitinol self-expanding coil stent and to provide angiographic data on the effect of self-expansion during implantation and follow-up. Self-expanding stents do not reach their nominal diameter at implantation. The long-term effects may therefore depend, in part, on continued expansion after initial implantation.
Between January 1995 and January 1996, 86 stents were deployed in 64 patients for indication of suboptimal results. All patients were clinically followed up for 1 year, and 72% had follow-up angiography.
The majority (55%) of the lesions were class B2 or C. Balloon angioplasty increased the minimal lumen diameter from 1.07 +/- 0.73 mm to 2.24 +/- 0.57 mm; stent deployment further increased the diameter to 2.63 +/- 0.48 mm, and within-stent balloon dilatation to 2.96 +/- 0.62 mm. Angiographic follow-up performed at 7.8 +/- 1.1 months (range 7-9 months) showed that the minimal lumen diameter was 2.15 +/- 0.80 mm (late lumen loss of 0.81 +/- 0.69 mm), and the mean stent diameter expanded to 3.58 +/- 0.48 mm (self-expanding late stent gain of 0.62 +/- 0.55 mm). The extent of this expansion was inversely related to the late lumen loss (r = 0.67, slope 0.81, P <.01). At 1 year 51 (80%) of 64 patients were event free; 3 had undergone coronary artery bypass grafting, 2 had had a myocardial infarction, and 9 had repeat angioplasty. In the subgroup of a simple lesion (<15 mm) covered by 1 stent, 18 (86%) of 21 patients were event free.
The self-expanding nitinol stent exerts its acute effect on minimal lumen diameter through its intrinsic radial force aided by balloon expansion. The stent continues to expand until it reaches its nominal diameter over the follow-up period. The extent of this expansion is inversely related to the late lumen loss, leading to an acceptable rate of long-term clinical events in this first cohort of patients with complex disease morphology.
American Heart Journal 09/1999; 138(2 Pt 1):326-33. · 4.65 Impact Factor
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ABSTRACT: The coronary artery collateral circulation may be beneficial in protecting against myocardial ischemia and necrosis. However, there is a tremendous interindividual variability in the degree of new collateral formation in patients with coronary artery disease. The basis for this interindividual heterogeneity is not understood. In this study we test the hypothesis that failure to generate collateral vessels is associated with a failure to appropriately induce with hypoxia or ischemia the angiogenic factor, vascular endothelial growth factor (VEGF).
We correlated the VEGF response to hypoxia in the monocytes harvested from patients with coronary artery disease with the presence of collaterals visualized during routine angiography. We found that there was a highly significant difference in the hypoxic induction of VEGF in patients with no collaterals compared with patients with some collaterals (mean fold induction 1.9+/-0.2 versus 3.2+/-0.3, P<0.0001). After subjecting the data to ANCOVA, using as covariates a number of factors that might influence the amount of collateral formation (ie, age, sex, diabetes, smoking, hypercholesterolemia), patients with no collaterals still have a significantly lower hypoxic induction of VEGF than patients with collaterals.
This study provides evidence in support of the hypothesis that the ability to respond to progressive coronary artery stenosis is strongly associated with the ability to induce VEGF in response to hypoxia. The observed interindividual heterogeneity in this response may be due to environmental, epigenetic, or genetic causes. This interindividual heterogeneity may also help to explain the variable angiogenic responses seen in other conditions such as diabetic retinopathy and solid tumors.
Circulation 09/1999; 100(5):547-52. · 14.74 Impact Factor
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ABSTRACT: The geometry of the heart plays a major role in cardiac function. The purpose of this study was to characterize analytically the geometric properties of the left ventricular (LV) three-dimensional (3D) shape, while excluding the effects of aspect ratio and size. Two groups of human hearts were studied by Cine-CT. The first group was composed of 10 healthy volunteers and the second of 9 pathological hearts. The hearts were scanned from apex to base. The endocardial borders of each LV scan were traced and used to reconstruct the 3D LV at end-diastole (ED) and end-systole (ES). Using a special normalized helical shape descriptor, denoted "geometrical cardiogram" (GCG), the typical 3D normal ED and ES shapes were determined. These typical shapes were then analytically approximated via a discrete cosine transform (DCT). The shape of each LV was then investigated for its correspondence to five analytically defined shapes: (i) a cone, (ii) a sphere, including all ellipsoidal shapes, (iii) a cylinder, (iv) a truncated ellipsoid, and (v) the DCT approximation of the normal LV shape. The results indicate that the normal LV shape can be well approximated by using only seven coefficients of the DCT. Conicity was the only geometrical feature which did not change from ED to ES in the normal group of hearts. The most prominent shape difference between normal and abnormal hearts was the significantly reduced conicity of the latter. Conicity is an important feature of LV geometry. The possible contribution of the conical shape to LV ejection efficiency is also discussed.
Computers and Biomedical Research 07/1999; 32(3):264-82.
