Automatic Boundary Detection Research Articles

Quantification of left ventricular function with contrast-enhanced harmonic colour Doppler and a semiautomated boundary detection algorithm in technically difficult patients: feasibility, accuracy, and inter-observer variability.

Patients with poor quality echocardiograms impede the application of available automatic boundary detection technologies. Tissue harmonic imaging and contrast media can allow optimal differentiation of left ventricular blood pool and tissue, making it possible to utilize automatic boundary detection software for automatic non-operator-dependent computation of left ventricular volumes. We integrated contrast-enhanced harmonic colour Doppler with a semiautomated boundary detection algorithm to explore the feasibility, accuracy and inter-observer variability for left ventricular volume assessment in technically difficult patients. Twenty-six patients with more than two segments not clearly visualized in tissue harmonic imaging were studied with contrast-enhanced harmonic colour Doppler using Levovist. Twenty patients (77%) achieved full left ventricular contrast filling without apparent blooming artefacts. Contrast-enhanced harmonic colour Doppler-automatic boundary detection was successfully implemented in these 20 patients, despite three (15%) in which it was not possible to acquire more than three cardiac cycles' values. Contrast-enhanced harmonic colour Doppler-automatic boundary detection measurements agreed closely with the manually drawn data. Among the three independent readers in the three techniques, the best correlation, lowest SEE, smallest limits of agreement and inter-observer variability were obtained in contrast-enhanced harmonic colour Doppler-automatic boundary detection. Contrast-enhanced harmonic colour Doppler-automatic boundary detection was feasible and accurate in estimation of left ventricular volume and function in patients with poor acoustic windows. This technique significantly reduced inter-observer variability, thus improving reliability and confidence of investigators in left ventricular function assessment. Contrast-enhanced harmonic colour Doppler-automatic boundary detection may have great potential in clinical evaluation of left ventricular volume and function, especially when on-line software is available.

Knowledge Based Automated Boundary Detection for Qualifying of LV Function in Low Contrast Angiographic Images

A Cardiac function is evaluated quantitatively by analyzing a shape change of the heart wall boundaries in angiographic images. To begin with, a boundary detection of end systolic left ventricle (ESLV) and end diastolic left ventricle (EDLV) is essential for the quantitative analysis of the cardiac function. Conventional methods for the boundary detection are almost semi-automatic, and a knowledgeable human operator’s intervention is still required. Manual tracing of the boundaries is currently used for subsequent analysis and diagnosis. However, these methods do not cut excessive time, labor, and subjectivity associated with manual intervention by a human operator. Generally, EDLV images have noncontiguous and ambiguous edge signal on some boundary regions. In this paper, we propose a new method for an automated detection of left ventricle (LV) boundaries in noncontiguous and ambiguous EDLV images. The proposed boundary detection scheme is based on a priori knowledge information and is divided into two steps. The first step is to detect EDLV boundary using ESLV boundary. The second step is to correct the detected EDLV boundary using the left ventricle (LV) shape information. We compared the proposed method with the manual method to detect the EDLV boundary. And through the experiments of the proposed method, we verified the usefulness of this method.

Effects of pacing-induced and balloon coronary occlusion ischemia on left atrial function in patients with coronary artery disease

OBJECTIVESThe aim of this study was to compare left atrial (LA) function in 16 patients with distal left anterior descending (LAD) and in 16 patients with proximal left circumflex (LCx) coronary artery stenosis at rest and immediately after pacing-induced tachycardia (LAD-pacing [P] and LCx-P) or coronary occlusion (LAD-CO and LCx-CO).BACKGROUNDDuring left ventricular (LV) ischemia, compensatory augmentation of LA contraction enhances LV filling and performance. The left atrium is supplied predominantly by branches arising from the LCx. Therefore, we hypothesized that one mechanism for the loss of atrial contraction may be ischemic LA dysfunction.METHODSLeft ventricular and LA pressure–area relations were derived from simultaneous double-tip micromanometer pressure recordings and automatic boundary detection echocardiograms.RESULTSImmediately after pacing or after coronary occlusion, LV end-diastolic pressure, LV relaxation, LA mean pressure and LV stiffness significantly increased in all patients. However, the area of the A loop of the LA pressure–area relation, representing the LA pump function, significantly decreased in groups LCx-P and LCx-CO (from 14 ± 3 to 9 ± 2, and from 16 ± 4 to 9 ± 2 mm Hg·cm2, respectively, p < 0.05), whereas it increased in groups LAD-P and LAD-CO (from 12 ± 3 to 54 ± 10, and from 16 ± 3 to 49 ± 8 mm Hg·cm2, respectively, p < 0.001).CONCLUSIONSIn patients with LAD stenosis, LV supply or demand ischemia is associated with enhanced LA pump function. However, in patients with proximal LCx stenosis who develop the same type and degree of ischemia, LA branches might have been affected, rendering the LA ischemic and unable to increase its booster pump function.

Electrocardiogram signal preprocessing for automatic detection of QRS boundaries

Automatic detection of QRS onset and offset points with reasonable accuracy has been a difficult task, approached since the first attempts at computerised electrocardiogram interpretation. The problem is additionally complicated by the usual presence of power-line interference, electromyogram artefacts and baseline fluctuation in the original signal, especially in multiphase complexes with small q, r, r′, or s′ waves. We propose a preprocessing method guaranteeing accurate preservation of the QRS boundaries, even in the existence of strong power-line or electromyogram noise. Examples of detection of QRS onset and offset points and a comparison with observer markings are presented for the assessment of preprocessing efficiency and detection consistency.

Real Time Determination of Left Atrial Volume by Automatic Boundary Detection: Comparison with Two-dimensional Echocardiographic Measurement

Real Time Determination of Left Atrial Volume by Automatic Boundary Detection: Comparison with Two-dimensional Echocardiographic Measurement

Assessment of Left Atrial Pressure–Area Relation in Humans by Means of Retrograde Left Atrial Catheterization and Echocardiographic Automatic Boundary Detection: Effects of Dobutamine

Objectives. This study sought to validate and apply a new method for obtaining the left atrial (LA) pressure–area relation.Background. In physiologic investigations, the pressure–area relation is the most accurate and representative index of LA hemodynamic status.Methods. We applied real-time two-dimensional echocardiographic imaging with automatic boundary detection to estimate LA area changes. To obtain LA pressure, a catheter-tipped micromanometer was introduced retrogradely into the left atrium using a steerable cardiac catheter developed at our institution. Twenty-five patients (11 normal subjects, 7 patients with an enlarged left atrium due to heart failure, 7 patients with atrial fibrillation) were studied before and after dobutamine administration. From the LA pressure–area relation, the area of the A loop (the first counterclockwise loop) and the V loop (the second clockwise loop), the pressure–minimal area relation and the LA passive elastic chamber stiffness constant were measured.Results. Normalized pressure–minimal area relation was highly linear and sensitive to changes in inotropic state (normal subjects: from 0.96 to 1.27 mm Hg/cm2, p < 0.01; patients with heart failure: from 0.59 to 0.68 mm Hg/cm2, p = NS; patients with atrial fibrillation: from 0.80 to 1.06 mm Hg/cm2, p < 0.05). The LA stroke work index was accurately calculated, and a very good correlation was found with LA preload. LA stroke work index was lower in patients with heart failure (3.9 ± 0.8 cm2·mm Hg, p < 0.001), whereas the LA stiffness constant was increased in patients with heart failure (0.801 ± 0.097 cm−2, p < 0.01) and atrial fibrillation (0.796 ± 0.091 cm−2, p < 0.01) compared with normal subjects (stroke work index 7.3 ± 1.9 cm2·mm Hg, stiffness constant 0.623 ± 0.107 cm−2, respectively). In addition, increased inotropic state after dobutamine administration resulted in improved LA pump function (stroke work index) in normal subjects (from 10.2 ± 0.9 to 13.8 ± 1.9 cm2·mm Hg, p < 0.001) and patients with heart failure (from 4.3 ± 0.4 to 7.6 ± 0.4 cm2·mm Hg, p < 0.001), as well as in decreased stiffness constant in all groups of patients (normal subjects: from 0.712 ± 0.141 to 0.473 ± 0.089 cm−2; patients with heart failure: from 0.896 ± 0.181 to 0.494 ± 0.093 cm−2; patients with atrial fibrillation: from 0.779 ± 0.145 to 0.467 ± 0.086 cm−2, p < 0.001).Conclusions. The method described here is both safe and reproducible for obtaining the LA pressure–area relation. LA function is impaired in patients with heart failure and in those with atrial fibrillation and may be acutely improved with inotropic agents in both normal and diseased atria.

Assessment of Left Atrial Function Using Instantaneous Pressure-Volume Relations in Mitral Stenosis before and after Percutaneous Mitral Balloon Valvuloplasty

Background:The left atrium functions as a reservoir for blood stored during ventricular systole, a conduit for pulmonary venous flow during ventricular diastole, and as a pump augmenting left ventricular filling during atrial systole. Cardiac angiography and Doppler echocardiography have been used in the assessment of atrial function. These measurements are, however, quite sensitive to ventricular and atrial loading conditions. Instantaneous pressure-volume relations of the left atrium have been described by a time-varying elastance model in the isolated left atrium and intact circulation in animal models. The mitral stenosis can be characterized hemodynamically as increased afterload of the left atrium. Percutaneous mitral balloon valvuloplasty, which results in a dramatic increase in the mitral orifice area in patients with mitral stenosis, is a well-suited clinical model for physiological assessment of the left atrial function in response to acute change of the left atrial afterload. The purpose of this study was 1) to evaluate the feasibility of the left atrial pressurevolume loop using automatic boundary detection method, 2) to obtain the left atrial pressure-volume loop in patients with mitral stenosis and to compare with that of normal controls, and 3) to assess the changes of the left atrial wall tesion and stroke work after percutaneous mitral balloon valvuloplasty in patients with mitral stenosis using the left atrial pressure-volume relations. Methods:Twelve patients had simultaneous measurements of left atrial pressure and left atrial volume using trasseptal catheterization and twodimensional echocardiography with automatic boundary detection technology. The left atrial pressure-volume was constructed by a computer workstation interfaced with an ultrasound system. Left atrial volumetric parameters, areas of A and V loops, and peak wall tension were measured and compared before and after 논문접수일:1998년 2월 6일 심사완료일:1998년 4월 27일 교신저자:하종원, 120-140 서울 서대문구 신촌동 134번 연세대학교 의과대학 심장혈관센터 심장내과학교실 전화:(02) 361-7071·전송:(02) 393-2041 E-mail:jwha@yumc.yonsei.ac.kr

Impact of presence of abnormal wall motion on echocardiographic determination of left ventricular function with automated boundary detection technique: re-evaluation.

It is still unclear whether echocardiography with an automated boundary detection technique (ABD) can accurately determine the left ventricular (LV) volume and function particularly in the presence of LV wall asynergy. We intended to re-evaluate the reliability and application of the ABD, which was based on the acoustic quantification technique (Sonos 2500, Hewlett Packard) for the LV volume measurement in patients without or with LV wall asynergy. A total of 80 patients (mean age 56 years) who underwent left ventriculography (LVG) were divided into two groups. The group A consisted of 29 patients with normal LV wall motion and the group B consisted of 51 patients with generalized or regional LV wall motion abnormality. In group A patients, the LV end-diastolic volume (LVEDV) was 96 +/- 25 ml by ABD and 112 +/- 33 ml by LVG and those of LV end-systolic volume (LVESV) were 44 +/- 14 ml by ABD and 48 +/- 17 ml by LVG, thus resulting in the underestimation of LV volume by 12% in average. Under these conditions, the LV ejection fraction (LVEF) by ABD, 54 +/- 8%, correlated well with that by LVG, 58 +/- 7%. Although underestimation of LV volume by 17% in average also occurred in groups B (N.S.), LVEF was found to correlate well with that by LVG; 27 +/- 8% vs 30 +/- 11% (r = 0.87, SEE = 3.1%) for 21 patients with the generalized LV asynergy; 39 +/- 10% vs 39 +/- 12% (r = 0.86. SEE = 3.3%) for 30 patients with the regional LV asynergy. These results demonstrate the feasibility of the ABD in determining the LVEF, although underestimation can occur in measuring the absolute LV volume in patients with or without LV asynergy.

Computerized quantification analysis of left ventricular wall motion from echocardiograms.

Two-dimensional echocardiography (2-D echo) imaging is a more attractive clinical tool than other modalities that either involve radiation exposure or are too slow to image heart motion in real-time. Computer-aided analysis of left ventricular(LV) wall motion provides quantitative parameters for diagnosis. This study presents a computerized model for quantitative analysis of left ventricular wall motion from two-dimensional echocardiography by the application of image processing algorithms, including automatic threshold estimation, contrast stretching, boundary detection and border smoothing. The wall motion measurements rely primarily on sequential changes from end-diastolic to end-systolic frames in the left ventricular contours of apical four-chamber view echocardiograms. Left ventricular wall motion was analyzed on the 30 segments of 5 patients with acute myocardial infarction. The results from the computerized model were compared to those obtained from qualitative analysis of echocardiograms by an experienced clinical cardiologist who was unaware of the results of quantitative data.

Echocardiography values in the halothane uptake phase--measurement by acoustic quantification and manual evaluation

In 35 ASA group I and II patients we investigated the influence of haemodynamic changes induced by increasing concentrations of halothane (from 0.0 to 0.6% halothane in 70% N20) on parameters of transesophageal echocardiography (TEE). Measurements by TEE were taken in manual and automatic boundary detection mode. In manual mode the left ventricular endsystolic area (ESA) increased significantly (+16.3%) and the fractional area change (FAC) decreased significantly (-14.9%). There was no significant change of left ventricular end diastolic area (EDA). In the automatic mode there was a significant increase of ESA and EDA (+13.8%; +6.0%) and a significant decrease of FAC (-10.9%). Peak ejection rate (PER) and peak filling rate (PFR) which were also assessed in automated mode decreased significantly (-10.0%; -5.7%) under halothane. No change occurred with manually determined left ventricular endsystolic wall stress (LVEWS). The endsystolic quotient decreased significantly both in manual and automated mode during halothane (-28.3%; -29.9%). No significant difference existed between TEE measurements under apnoea versus under controlled ventilation (except for EDA in automated mode). We conclude that there is no need for apnoea conditions for TEE measurements. In conclusion, TEE proves a useful monitoring system in anesthesia which enables the investigator to assess the negative inotropic effect of halothane. Problems in its practical usage are due to the wide variation of TEE measurements.

Assessment of right ventricular function in patients with congestive heart failure by echocardiographic automated boundary detection

In conclusion, our findings demonstrate that right ventricular function in patients with chronic heart failure due to dilated cardiomyopathy can be reliably assessed by an echocardiographic ABD technique, which is superior to conventional manual echocardiographic methods. This technique, providing a real-time display of right ventricular function without exposure to radiation, offers important advantages when compared with radionuclide ventriculography. For these reasons, we believe that in patients with heart failure, the ABD technique will have an expanding role in noninvasively assessing right ventricular function.

Improvement of left ventricular diastolic dysfunction in hypertensive patients 1 month after ACE inhibition therapy: evaluation by ultrasonic automated boundary detection.

The purpose of this study was to detect any improvement in left ventricular diastolic dysfunction in hypertensive patients 1 month after cilazapril therapy. Twenty-three patients, 5 men and 18 women (mean age, 53.52 +/- 9.10 years), with mild or moderate hypertension (160 +/- 13/98 +/- 10 mm Hg), and free of other cardiac or systemic diseases, were studied using ultrasonic automated boundary detection (ABD) and pulsed Doppler echocardiography, before and 1 month after a daily dose of 2.5 mg of cilazapril. The following new ABD diastolic indices were determined: the time rate of area change in early diastole (dA/dt)E, that in late diastole (dA/dt)A, and their ratio (dA/dt)E/(dA/dt)A, while Doppler transmitral flow measurements of left ventricular diastolic filling were also simultaneously recorded. The ABD results showed left ventricular diastolic dysfunction (LVDD) in 9 of 23 patients (39%) compared with the ABD values of 12 normal volunteers. Neither method revealed any significant difference before and after treatment in the patient group as a whole. However, in the group of 9 patients with diastolic dysfunction, the ABD ratio (dA/dt)E/(dA/dt)A was significantly improved after cilazapril therapy (1.20 +/- 0.21 versus 1.41 +/- 0.17; P < 0.05). We concluded that a large percentage (39%) of patients with mild or moderate hypertension had reduced diastolic performance of the left ventricle at a stage of the disease when systolic dysfunction and/or hypertrophy were not evident. Significant improvement of diastolic dysfunction in hypertensive patients could be detected by the proposed ABD new diastolic indices 1 month after cilazapril therapy. In conclusion, automatic boundary detection should be a useful non-invasive modality for the early diagnosis of left ventricular diastolic dysfunction, as well as early recognition of its improvement.

Automatic detection of accentual phrase boundaries using prosodic features and phoneme boundaries

There are two approaches for constructing an appropriate fundamental frequency (F0) control method for speech synthesis: statistical and rule-based. The statistical approach has the advantage of automatic training, but it requires a large corpora of speech that is annotated with prosodic boundaries. Recently, a method is proposed for high-accuracy detection of these boundaries [Ostendorf and Ross (1996)], given a set of prosodic boundary candidates in which almost all the correct boundaries are included. This paper proposes a detection method to generate these boundary candidates, specifically for accentual phrases which represent one of the smallest prosodic units. The detection algorithm uses local maximums and minimums of the F0 contour and low-energy regions of the speech waveform for finding candidate regions that correspond to accentual phrases and pauses in speech. The candidate phrase boundaries are then aligned to the nearest phoneme boundaries, which are detected automatically using forced alignment with a speaker-independent speech recognition system given a phoneme transcription. This method was applied to 250 read Japanese sentences. High-detection accuracy (97%) was obtained, with almost all the missed detections having valid candidates within ±3 phonemes. The insertion error rate was less than double the number of correct boundaries.

On line assessment of right ventricular function in patients with chronic congestive heart failure by echocardiographic automated boundary detection — Comparison with tricuspid annular plane systolic excursion and gated blood pool ventriculography

On line assessment of right ventricular function in patients with chronic congestive heart failure by echocardiographic automated boundary detection — Comparison with tricuspid annular plane systolic excursion and gated blood pool ventriculography

Real-time determination of left ventricular ejection fraction by automatic boundary detection in patients with dilated cardiomyopathy: a comparison with radionuclide ventriculography.

Echocardiographic automatic boundary detection (ABD) is a new on-line technique which automatically outlines the left ventricular endocardial border and instantly calculates the left ventricular area and volume from two dimensional echocardiographic images. To determine if left ventricular ejection fraction (LVEF) can be derived using the ABD method, 25 consecutive patients with dilated cardiomyopathy, aged 52.1 +/- 15.2 (range 14 approximately 75), underwent complete echocardiographic examination with both the ABD method and radionuclide ventriculography (RVG). End-diastolic and end-systolic left ventricular areas were obtained on-line from the apical four chamber view. Left ventricular length was also measured from an apical view. Left ventricular volumes and ejection fraction were calculated using the single plane area-length method. ABD measurements could be obtained in all patients. Linear regression analysis compared ejection fraction derived by ABD and RVG. The mean radionuclide LVEF was 20.9 +/- 6.8% and mean ABD-derived LVEF was 22.7 +/- 5.8%. Linear regression analysis revealed that the ABD-derived LVEF is closely correlated with the RVG-derived LVEF (r = 0.87, p < 0.001). In conclusion, ABD echocardiography is a new on-line technique which may be used to accurately calculate LVEF in patients with dilated cardiomyopathy.

Left atrial size and function: assessment using echocardiographic automatic boundary detection.

To evaluate the waveforms of left atrial area changes obtained by automated boundary detection with newly developed acoustic quantification technology. All subjects had measurements of left atrial areas taken in the apical four chamber, parasternal long axis, and parasternal short axis views using both conventional echocardiographic methods and automatic boundary detection on two occasions separated by at least a week. On the second visit measurements were also repeated in healthy volunteers after acute intravenous volume loading with 1 litre of saline over 2-5 minutes. A university medical school echocardiographic laboratory. 12 healthy male volunteers and 8 patients with cardiac disease (5 with congestive heart failure, 1 with mitral stenosis, and 2 with hypertensive left ventricular hypertrophy, and dilated left atria). There was close correlation between conventionally derived left atrial areas and those obtained by automatic boundary detection, particularly in the apical four chamber view (r = 0.98). Both inter and intra observer variabilities (coefficient of variation) for left atrial areas measured by automatic boundary detection were good (4.7-14.2% and 8.1-18.6% respectively). The reproducibility (coefficient of variation) for derived indices of left atrial function, however, was much poorer (10.4-104.8% and 12.5-88% respectively). After acute volume loading significant increases in left atrial area were observed at all stages in the cardiac cycle. These data demonstrate that although the reproducibility of left atrial functional indices is poor, instantaneous left atrial cavity measurements with automatic boundary detection are reproducible. This suggests that automatic boundary detection may assist in serial non-invasive measurement of left atrial size to assess disease states and treatments.

The clinical utility of automatic boundary detection for the determination of left ventricular volume: A comparison with conventional off-line echocardiographic quantification

The aim of this study was to compare measurements of echocardiographic volume with an on-line automatic boundary detection imaging system with those of a conventional off-line method for routine clinical studies. Automatic boundary detection imaging shows promise as a rapid, on-line method for quantitating left ventricular volumes by echocardiography. However, there is little information about the role of automatic boundary detection for routine clinical studies. Ninety-seven patients with a variety of clinical diseases who were referred for clinical transthoracic echocardiographic evaluation were studied in apical four-chamber and two-chamber imaging planes. End-diastolic volume, end-systolic volume, and ejection fraction obtained with automatic boundary detection images were compared with those of conventional off-line analysis. Segmental endocardial definition and border tracking were evaluated on all automatic boundary detection images. Left ventricular end-diastolic volumes obtained by automatic boundary detection correlated well but were systematically under-estimated compared with off-line analysis for the apical two-chamber (r = 0.83; underestimation = 42 +/- 33 ml; p < 0.05) and four-chamber views (r = 0.83; underestimation = 43 +/- 31 ml; p < 0.05). Left ventricular end-systolic volumes also correlated well but were underestimated by automatic boundary detection for the apical two-chamber (r = 0.83; underestimation = 14 +/- 26 ml; p < 0.05) and four-chamber views (r = 0.83; underestimation = 18 +/- 24 ml; p < 0.05). Ejection fraction was not predicted accurately for the entire study population (n = 97). However, for patients with complete endocardial definition (n = 32), automatic boundary detection accurately predicted ejection fraction with no systematic error compared with manually traced images for both the apical two-chamber (r = 0.86; p < 0.05) and four-chamber (r = 0.82; p < 0.05) views. Segmental analysis of endocardial tracking revealed significantly better tracking of the septal and lateral walls compared with other regions (p < 0.05). End-diastolic and end-systolic volumes determined by automatic boundary detection correlate well but underestimate volume compared with conventional off-line analysis. However, ejection fraction compares favorably for the two methods when there is complete endocardial definition.

Echocardiographic assessment of systolic and diastolic left ventricular function using an automatic boundary detection system. Correlation with established invasive and non invasive parameters.

Systolic and diastolic left ventricular function was assessed using an echocardiographic automatic boundary detection system (ABD) in 50 unselected patients undergoing left cardiac catheterisation. Automatic boundary detection system derived parameters (fractional area change [FAC], peak positive rate of area change [+dA/dt] and peak negative rate of area change [-dA/dt]) were compared with invasively (left ventricular angiography and pressures) and non invasively (Doppler mitral filling velocities and isovolumic relaxation time) acquired conventional indices of ventricular function. Adequate detection of endocardial boundaries and subsequent measurements using the ABD system were achieved in 40/50 (80%) patients in the short axis parasternal view, in 41/50 (82%) in the apical four chamber view and in 34/50 (68%) in both views. For the whole group of patients the FAC (maximal left ventricular diastolic area--minimal left ventricular systolic area/maximal left ventricular diastolic area) estimated in the short axis view correlated with the angiographic ejection fraction (EF) measured in the right oblique projection (r = 0.51, p < 0.001). There was only a weak correlation of the FAC estimated in the apical four chamber view with the EF (r = 0.36, p < 0.01). The mean FAC (mean value of the FAC in the short axis and apical four chamber views) correlated reasonably with the EF (r = 0.62, p < 0.0001). There was no correlation between ABD derived parameters and left ventricular end diastolic pressure (LVEDP) in these patients. In a subgroup of patients with normal coronary arteries and left ventricular function (n = 17), although there was no correlation between EF and FAC, there was a strong positive correlation between FAC (apical four chamber and mean) and LVEDP (r = 0.77, p < 0.01 and r = 0.87, p < 0.01 respectively). No correlation was found in these patients between EF and LVEDP. In a further subgroup of patients with angiographically abnormal left ventricular function (EF < 45%), there was a positive correlation between FAC (short axis, apical four chamber and mean) and EF (r = 0.52, p < 0.05, r = 0.83, p < 0.0001 and r = 0.80, p < 0.001 respectively) and a negative correlation between FAC (short axis and mean) and LVEDP (r = -0.52, p < 0.05 and r = -0.60, p < 0.01 respectively). There was also a negative correlation between LVEDP and EF in the same subgroup of patients (r = -0.65, p < 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Echocardiographic automatic boundary detection to measure left atrial function after the maze procedure

Automatic boundary detection (ABD) is a new echocardiographic modality providing continuous on-line measurements of cavitary area throughout the cardiac cycle. The maze procedure is a new surgical intervention designed to restore sinus rhythm and mechanical atrial contraction as a definitive treatment for patients with atrial fibrillations for whom medical therapy has failed. To evaluate whether ABD may define left atrial function in patients after the maze procedure, we obtained pulsed Doppler recordings of mitral inflow velocity and echocardiographic ABD in 25 patients, 6 +/- 2 months after the maze procedure. We measured the left atrial end-systolic cavitary area, mid-diastolic area before atrial contraction, and end-diastolic area (in square centimeters). Left atrial contraction by Doppler was compared with that derived by ABD in patients who underwent the maze procedure and control subjects (n = 13), both qualitatively and quantitatively (atrial filling fraction vs active atrial contraction [ABD] where atrial contraction (in percent) = (mid-diastolic area - end-diastolic area) x 100/(end-systolic area - end-diastolic area in percent]). Restoration of atrial contraction after the maze procedure was detected by Doppler in 19 patients (76%) and by ABD in 21 patients (84%). The atrial filling fraction was 19 +/- 4% in patients compared with values of 34% +/- 8% in control subjects (p < 0.001). By ABD atrial contraction was 20% +/- 6% in patients whereas control subjects exhibited values of 41% +/- 14% p < 0.001). The Doppler-derived atrial filling fraction and ABD-derived atrial contraction were closely correlated (r = 0.91; p < 0.001; y = 0.59x + 8.6). Thus Doppler techniques complemented by ABD provide direct quantitative indexes of left atrial function throughout the cardiac cycle. Although left atrial contraction and filling are reduced after the maze procedure, left atrial function is restored in most patients with a history of atrial fibrillation, and echocardiographic ABD is a sensitive technique for its detection.

785-2 Clinical Feasibility of Echocardiographic Automated Boundary Detection in Monitoring Left Ventricular Response to Acute Changes of Preload in Normal Subjects

Automated Boundary Detection (ABD), recently incorporated into standard echocardiographic system, provides an on-line instantaneous measurement of left ventricular (LV) volume and its derivative as a function of time (dV/dt). The aim of our study was to test the clinical feasibility of ABD in monitoring acute LV changes. We evaluated the LV response to acute changes in preload in 15 normal males (mean age 32 ± 6 years), examined 5 times: in the supine position (A). with legs elevated 45° to 60° (B), back in the supine position (C), 5’ after the simultaneous inflation of blood pressure cuffs at the root of the 4 limbs (D) (pressure of the cuffs set at 10 mmHg below the basal diastolic pressure of each subject) and back in the supine position (E). Real time LV volumes by ABD were obtained in the 4 chamber view, with gains optimized to detect the most continuous ABD. We evaluated: systolic (SBP) and diastolic blood pressure (DB PI, heart rate (HR), LV end-diastolic (EDV) and end-systolic volume (ESV). ejection fraction (EF). normalized peak filling rate (PFR), defined as maximal positive dVldt, and normalized peak ejection rate (PER), defined as maximal negative dVldt, both standardized for EDV. A B C D E SBP (mmHg) 119 ± 12 122 ± 11 120 ± 10 117 ± 10 121 ± 11 DBPlmmHg) 77 ± 6 79 ± 6 76 ± 8 77 ± 5 78 ± 5 HR (bimini 66 ± 4 68 ± 6 65 ± 5 66 ± 5 67 ± 6 EDV(ml) 91 ± 22 102 ± 30 * 89 ± 20 75 ± 21 ** 87 ± 19 ESV(mll) 33 ± 10 43 ± 11 * 35 ± 13 26 ± 11 * 32 ± 9 EF % 61 ± 10 57 ± 9 60 ± 8 64 ± 10 59 ± 7 PFR (mllsec) 448 ± 0.7 4.49 ± 06 4.45 ± 0.7 5.03 ± 0.7 * 451 ± 08 PER (mllsec) 4.20 ± 0.5 4.00 ± 04 4 0.14 ± 0.5 4.77 ± 0.5 ** 4.23 ± 06 * p &lt; 0.005; ** P &lt; 0.001 Bvs A, D vs C Measurements in A, C and Ewere practically identical, thus demonstrating a good reproducibility of the ABD technique. Our results demonstrate that ABO can be used in clinical practice when acute changes in LV volume and its rate of change are to be monitored.