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Biomedical subjects

D A Conetta

Publications and source records attributed to D A Conetta.

At least 19 recordsLinked to original sources
PubMed1998

Autonomous epicardial and endocardial boundary detection in echocardiographic short-axis images.

An autonomous endocardial and epicardial boundary detection (ABD) method is reported. One hundred ten cycles from 55 clinical studies were selected retrospectively. Image sequences were digitized at 512 x 480 pixel resolution. The point-by-point boundary positions of the ABD and the areas enclosed were compared with positions and enclosed areas drawn by three independent observers. Correlation coefficients for epicardial end-diastolic (ED) and end-systolic (ES) areas, endocardial ED and ES areas, muscle area, and fractional area change were 0.970, 0.976, 0.951, 0.985, 0.887, and 0.878, respectively. Bland-Altman analysis showed negligible biases with standard deviations comparable to those of the observers. The mean difference between the ABD border and the consensus observer border positions in 64 directions falls within the mean range of interobserver border positions, suggesting that shape is also well defined by the ABD.

Echocardiography↗
PubMed1996

Automatic identification of papillary muscles in left-ventricular short-axis echocardiographic images.

An automatic method for identifying the location of the papillary muscles in two-dimensional (2-D) short-axis echocardiographic images is described. The technique uses both spatial and temporal information to identify the presence and track the location of the muscles in the left ventricle from end-diastole to end-systole. The three main steps of the method are spatial preprocessing, spatial processing, and temporal processing. The spatial preprocessing step includes a region of search estimation. The spatial processing step includes a papillary muscle existence test and an initial approximation of the papillary muscle points. The temporal processing includes motion-pattern evaluation and final papillary muscle location. The estimates of existence and position for the automatic method were compared with estimates made by an independent expert observer. Two hundred and ten frames, three taken from each of 70 image sequences, were evaluated. Since two regions of search were processed for each frame (one for the posterior-inferior and one for the anterior-lateral papillary muscle), a total of 420 approximations were made. Of this total, 340 automatic estimates were judged to be in close agreement with estimates made by the expert. Of the remaining 80 approximations, 54 estimates were made by the expert when the computer determined that no papillary muscle was present, 17 estimates provided poor results, and nine estimates were made by the computer when the observer concluded that no papillary muscle was present.

Algorithms↗
PubMed1993

Single site experience with high-speed coronary rotational atherectomy.

This report describes a single site experience as part of a multicenter clinical trial with high-speed rotational atherectomy in human coronary arteries. A total of 108 patients with 143 lesions had interventions, were grouped by success or failure, and were analyzed by patient, lesion, and procedural variables. Satisfactory results were achieved in 131 of 143 lesions (92%) and 99 of 108 (92%) patients. Neither patient-related variables (age, gender, diabetes, hypertension, cigarette use, restenosis, previous myocardial infarction, and left ventricular function) nor lesion characteristics (length, ostial or bifurcation location, calcification, lesion classification, and coronary location) were predictive of poor outcome. Tears, acute closure, percentage stenosis after rotational atherectomy and after adjunctive balloon angioplasty were the procedural variables that were statistically associated with outcome by univariate methods. Multivariate analysis isolated postintervention residual stenosis as the only variable that was statistically different between groups. Serious complications included one death in the catheterization laboratory, one Q-wave myocardial infarction, three non-Q myocardial infarctions, and three emergency coronary bypass operations for sustained vessel closure. One patient required emergency surgery for a pacing wire perforation not related to the use of the device. The potential benefits of high-speed rotational atherectomy include increased safety in complex lesions, the ability to address lesions not amenable to balloon techniques, and the possibility of reducing the incidence of restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1993

Usefulness of left ventricular wall stress at rest and after exercise for outcome prediction in asymptomatic aortic regurgitation.

Sensitive indexes for detection of left ventricular (LV) systolic performance are necessary for optimal clinical management of asymptomatic patients with aortic regurgitation (AR). To investigate the prognostic value of noninvasively determined baseline LV wall stress, we studied 10 asymptomatic patients with AR who had normal LV systolic function on two-dimensional directed M-mode echocardiography at rest and after maximal treadmill exercise. At follow-up (mean 3.6 years) three patients (group A) had progressed to decompensated LV volume overload or death related to aortic valve disease (one cardiac death and two aortic valve replacements), and seven patients (group B) remained unchanged clinically and on serial echocardiographic study. Although baseline LV chamber dimensions and systolic performance at rest were similar in the two groups of patients, LV fractional shortening after exercise and LV wall stress at rest and after exercise were significantly different (p = 0.02). Noninvasively determined baseline LV wall stress at rest and after exercise may be useful indexes for determining prognosis in asymptomatic AR.

Adult↗
PubMed1990

Echocardiographic assessment of the left ventricle of endurance athletes just before and after exercise.

Fourteen normal subjects and 10 marathon runners were studied using postexercise echocardiography to assess left ventricular (LV) wall thickness, afterload and systolic performance. Cuff systolic blood pressures and M-mode echocardiographic recordings were obtained in the supine position before and within 2 minutes of termination of maximal treadmill exercise. Both groups had increased LV dimensional shortening (% fractional shortening) and stroke volume after exercise, although runners had larger increases compared to untrained normal subjects (p less than 0.05). Preload, as estimated by LV end-diastolic dimension, was greater in runners compared to normal subjects at rest (52 vs 48 mm, p less than 0.05). However, preload did not change after exercise in either group. Afterload, estimated by LV end-systolic wall stress, decreased after exercise in both groups; however, runners had lower afterload at rest and immediately after exercise compared to normal subjects (p less than 0.05). The runners' greater LV end-systolic wall thickness appears to account for their lower afterload. Data indicate that marathon runners have lower afterload at rest and greater decrease in afterload after maximal exercise, compared to untrained normal subjects.

Adult↗
PubMed1989

Separation of afterload reduction and a direct beneficial cardiac effect of nifedipine in congestive cardiomyopathy.

To assess whether the calcium antagonist nifedipine has a specific, direct effect on left ventricular diastolic function separate from its vasodilatory action, we studied 10 patients with idiopathic congestive cardiomyopathy (ages 28-69, New York Heart Association Class III or IV) at 30 min, 2 h, and 6 h after administration of 10 mg of sublingual nifedipine. Hemodynamic parameters were assessed with Swan-Ganz catheter and two-dimensional echo images were processed with computer-assisted analysis (Quantic 1200) to obtain left ventricular chamber areas and an index of rapid diastolic filling. Indices of left ventricular systolic performance (cardiac index and left ventricular area change fraction) improved during the early (30 min and 2 h) observation periods as afterload (estimated by systolic blood pressure and systemic vascular resistance) was reduced (p less than .05 vs. baseline). Pulmonary capillary wedge pressure fell from 17 mmHg to 11 mmHg and rapid diastolic filling index increased from .28 (% area change/ms) to .37 (% area change/ms) (p less than .05 vs. baseline) during the early observation periods. Indices of left ventricular systolic performance and afterload had returned to baseline at the late (6 h) observation period. However, pulmonary capillary wedge pressure remained reduced significantly at 10 mmHg after 6 h (p less than .05 vs. baseline). Preload (estimated by left ventricular end-diastolic chamber area) did not vary throughout the study period. Reduction of pulmonary capillary wedge pressure at 6 h, despite return of afterload reduction to baseline and no change in preload, suggests improved left ventricular chamber compliance after sublingual nifedipine, not related to alteration of left ventricular loading conditions.

Adult↗
PubMed1985

Reproducibility of left ventricular area and volume measurements using a computer endocardial edge-detection algorithm in normal subjects.

The variability of serially recorded 2-dimensional echocardiograms in normal subjects was determined. During a 2-week period, 10 normal subjects underwent echocardiography 5 times, in 2 laboratories, with use of different ultrasonographs. The video recordings were analyzed using a computer image analysis system (Quantic 1200) to provide standardized left ventricular short-axis areas and area ejection fraction (EF). Left ventricular volumes and volume EF were calculated. The 95% confidence limits of the percent difference for end-diastolic area and volume between 2 samples in a given subject were +/- 16.8 and +/- 16.7%, respectively. The limits for end-systolic area and volume were +/- 15.8 and +/- 17.0%, respectively. The 95% confidence limits for differences of area and volume EF between 2 recordings were +/- 12.8 and +/- 9.7%, respectively. No correlation was found between clinical grade (image quality) and the variability of area measurements. A good correlation (r = 0.98) was found between area and volume EF for any given subject over the 5 observations. These confidence limits are narrower than those previously recorded.

Adult↗
PubMed1985

Sublingual nifedipine: acute effects in severe chronic congestive heart failure secondary to idiopathic dilated cardiomyopathy.

Nine patients with chronic, severe (New York Heart Association class III to IV) congestive heart failure were studied to determine the acute effects of 10 mg of sublingual nifedipine on left ventricular (LV) function. Hemodynamic and echocardiographic data were obtained at rest and 30 minutes, 1, 2, 4 and 6 hours after nifedipine. Measurements at rest reflected LV dysfunction with elevation of end-diastolic volume index (102 +/- 46 ml/m2), pulmonary capillary wedge pressure (17 +/- 8 mm Hg), systemic vascular resistance (1,547 +/- 439 dynes s cm-5) and reduction of cardiac index (2.8 +/- 0.5 liters/min/m2). There were no adverse effects noted with administration of sublingual nifedipine. Initial changes through 1 hour reflected an unloading effect of nifedipine with reduction in pulmonary capillary wedge pressure (11 +/- 5 mm Hg) (p less than 0.05), systemic vascular resistance (1,179 +/- 289 dynes s cm-5) (p less than 0.01), end-diastolic volume index (91 +/- 37 ml/m2 [difference not significant]) and an increase in cardiac index (3.6 +/- 0.7 ml liters/min/m2) (p less than 0.01). Subsequently the cardiac index, systemic vascular resistance and end-diastolic volume index returned toward baseline. Only the pulmonary capillary wedge and pulmonary artery pressures demonstrated a sustained reduction through the 6-hour study period suggesting an effect of nifedipine on LV relaxation. Thus, sublingual nifedipine administered acutely to patients with clinical congestive heart failure is a safe and efficacious vasodilator.

Administration, Oral↗
PubMed1984

Evaluation of a three-dimensional reconstruction to compute left ventricular volume and mass.

This study tests the accuracy of a model to calculate left ventricular volume (LVV) and muscle volume (MV) when optimal data were used. These volumes were calculated using endocardial and epicardial borders traced from photos of cross sections of 20 animal (dog, goat and pig) hearts. A pyramid summation algorithm was used to perform a 3-dimensional (3-D) reconstruction based on 5 short-axis views, thus providing computer volume estimates. These were compared with the true (T) ventricular volumes determined by water filling of the cavity and the true MV based on weight. Because each heart was sliced in 5 planes, the appropriateness of the algorithm for MV could be tested for 6 regions. The pyramid summation algorithm consistently underestimated MV at the base and apex, but was accurate from the midmitral valve to the inferior papillary muscle region. Consequently, the total MV was computed as the midventricular MV, plus base and apex volumes computed from regression equations. Results showed that 3-D reconstruction resulted in a regression of LVVT = 1.02LVV3D + 10.30 ml with r = 0.987 for the chamber of MVT = 1.05 MV3D - 9.78 ml, with r = 0.967. It is concluded that the pyramid summation algorithm can accurately estimate volumes from spatially registered short-axis data with 95% prediction limits about the mean of the data of +/- 10 ml for left ventricular chamber volume and +/- 17.6 ml for MV.

Animals↗
PubMed1984

In vitro analysis of boundary identification techniques used in quantification of two-dimensional echocardiograms.

Echocardiographic cross-sectional areas of 10 formalin-fixed animal left ventricles were determined by 5 independent observers using black-white (B-W) and mid-spot (M-S) endocardial boundary identification techniques. The echocardiographic cross-sectional areas were compared with the true anatomic cross-sectional areas of the same 10 hearts to determine the accuracy, variability and reliability of each technique. The results of these comparisons revealed that the M-S technique was more accurate than the B-W technique (3.3 +/- 7.2 vs 34.9 +/- 8.6% error). However, the B-W technique was more reliable in that it had a smaller interobserver and estimated intraobserver variability. The M-S technique had a 6% greater intraobserver variability.

Animals↗
PubMed1984

Computer-assisted edge detection in two-dimensional echocardiography: comparison with anatomic data.

Four methods of computer-based edge detection were evaluated for identification of endocardial and epicardial borders on 2-dimensional echocardiograms of excised hearts. A method was also evaluated for observer identification of cardiac borders in the same hearts. The accuracy of computer-derived borders and of observer-derived borders were determined by comparison to anatomic borders measured from photographs of slices of the excised hearts. Echocardiographic borders were compared with anatomic borders by calculation of segmental cavity areas and wall thickness. Each of the methods tested (computer and observer) identified endocardial borders accurately, resulting in cavity segment areas that correlated well with the corresponding anatomic data (r = 0.90 to 0.92). Regional wall thicknesses correlated less well with anatomic data (r = 0.74 to 0.80), suggesting that endocardial borders were identified more accurately than were epicardial borders. Thus, the methods of computer-assisted echocardiographic border detection tested identified the endocardium and epicardium as accurately as a trained observer evaluating unprocessed echocardiograms. Computer-based methods of border detection may be useful in the automated analysis of clinical echocardiograms.

Animals↗
PubMed1984

Echocardiographic evaluation of responses to left ventricular volume loading by principal components and nomographic analysis.

Changes in performance of left ventricles (LV) with volume overloads are difficult to determine by conventional clinical methods. This information, however, is important for the proper timing of therapeutic interventions to preserve LV function. Seven size-adjusted (by regression with end-diastolic diameter, EDD) LV performance parameters from 100 normal echocardiograms (echos) were entered into a principal component analysis (PCA). Two factors (linear combination of the 7 parameters) were obtained from the analysis. Prediction limits (95%) about these two factors used in combination, correctly classified 92% of the normal echos. More detailed analysis of the two PCA factors revealed that the majority of the variability within the factors was explained by size-adjusted parameters resultant from the EDD posterior wall (factor 1) and EDD septal excursion (factor 2) regressions, respectively. Plots of the 95% prediction limits about these two regression lines provided nomograms. These nomograms used in combination, correctly classified 95% of the normal echos. When the performance parameters of 64 volume loaded ventricles were evaluated by PCA, four groups were identified. Ten ventricles (16%) were hypokinetic, 29 (45%) were hyperkinetic, 23 (36%) were nomokinetic, and 2 (3%) could not be classified. These classifications were supported by significant between group differences of shortening fraction, velocity of circumferential shortening, and velocity of circumferential expansion. Nomographic classification of the same volume loaded hearts was in excellent (94%) agreement with PCA classification. Nomographic analysis (derived from the PCA) is offered as a less complex, more clinically applicable echo method for evaluating LV performance of volume loaded hearts.

Adolescent↗
PubMed1984

Esophageal compression of the heart presenting as an extracardiac mass on echocardiography.

Echocardiography is helpful in the identification of extracardiac masses. The role of echocardiography in evaluating the effects of the masses on the heart is not well established. The case presented details the identification of and the evaluation by echocardiography of structural and functional effects of a massively dilated esophagus on the heart. Two-dimensional echocardiography revealed anatomic distortion due to a mass effect of the dilated esophagus on the left heart chambers. M-mode echo recordings demonstrated decreased left atrial and ventricular dimensions with increased atrial and ventricular fractional shortening. These findings normalized after Heller myotomy, without a change of estimated stroke volume.

Adult↗
PubMed1982

A mechanical arm for spatial registration of two-dimensional echocardiographic sections.

The accurate calculation of left ventricular (LV) wall motion from two-dimensional echocardiographs will require the accurate registration of the position from which each two-dimensional (2-D) view was obtained. This paper describes a mechanical arm with five degrees of freedom that was developed so that the position and orientation of 2-D echo sections could be calculated in three-dimensional space. High precision potentiometers, direct or gear driven, permit calibration and measurement of each of the five movements. Using the length of the arm and the angles measured by these potentiometers, the position of a 2-D section can be calculated with respect to a fixed reference point outside the body. The measurement arm was extensively retested after six months of clinical use. In patient studies, 95% confidence interval for positioning a cross-section of the long axis is +/- 6 mm. This error is similar to the cross-plane resolution to most contemporary two-dimensional transducers. On the basis of an extensive analysis of variance, recommendations are made to improve the accuracy of the arm.

Echocardiography↗