Regional Wall Motion Analysis Research Articles

Is There a Long-Term Predictive Value of Intraoperative Low-Dose Dobutamine Echocardiography in Patients Who Have Coronary Artery Bypass Graft Surgery with Cardiopulmonary Bypass?

In patients with coronary artery disease, chronic regional left ventricular systolic dysfunction at rest may be caused by hibernating or by infarcted myocardium. Intraoperative low-dose dobutamine (LDD) echocardiography reliably predicts the immediate recovery of regional myocardial function after coronary artery bypass graft (CABG) surgery. We sought to determine whether intraoperative LDD echocardiography would also predict recovery of regional function after 1 yr. Twenty-five patients with coronary artery disease who underwent CABG surgery with intraoperative LDD echocardiography were evaluated 1 yr later with a follow-up transthoracic echocardiogram. The covariates of left ventricular ejection fraction, old myocardial infarction, and diabetes mellitus were considered in an analysis of regional wall motion (RWM). A 16-segment model and a 1–5-point scoring system were used to evaluate 350 myocardial segments. Multiple logistic regression analysis was performed to determine whether response to intraoperative LDD echocardiography (5 μg · kg−1 · min−1) predicted changes in regional function at 1 yr. A segment was defined as stunned if the RWM score obtained during LDD infusion deteriorated after cardiopulmonary bypass but recovered in the 1-yr follow-up echocardiogram. A response to intraoperative LDD predicted changes in regional function at 1 yr. The overall odds of improvement in regional function were 2.22 times greater (95% confidence interval = 1.29, 3.82;P = 0.0039) with a positive response to intraoperative LDD. The positive predictive value of intraoperative LDD echocardiography for improvement in myocardial function was 0.81 and the negative predictive value was 0.34. The predictive values did not vary with the examined covariates. Of segments with unexpected deterioration of RWM immediately after cardiopulmonary bypass, 87% recovered at the time of the 1-yr follow-up echocardiogram. Contractile reserve demonstrated by intraoperative LDD echocardiography predicts regional function at 1 yr; however, the test cannot predict which segment will not recover. Most of unexpected regional ventricular systolic dysfunction immediately after CABG surgery can be attributed to myocardial stunning.

A rapid stress-testing protocol for the detection of coronary artery disease: Comparison of two-stage transesophageal atrial pacing stress echocardiography with dobutamine stress echocardiography

OBJECTIVESWe compared a new two-stage transesophageal atrial pacing stress echocardiography (TAPSE) protocol with a standard dobutamine stress echocardiography (DSE) protocol.BACKGROUNDTransesophageal atrial pacing stress echocardiography has been proposed as an efficient alternative to DSE.METHODSTwo-stage TAPSE (85% and 100% of age-predicted maximum heart rate) and DSE (5 to 40 μg/kg/min at 3-min stages with or without atropine) were both performed, in random sequence, in each patient of a study group of 36 patients. Regional wall-motion analysis, patient acceptance (1 = low, 5 = high), hemodynamics and duration for performing and interpreting tests were compared.RESULTSTransesophageal atrial pacing stress echocardiography was successful in 35 of the 36 patients (feasibility 97%). More TAPSE than DSE studies were called “ischemic” (37% vs. 14%; p = 0.005). Peak heart rate was higher with TAPSE (144 ± 18 vs. 129 ± 15 beats/min, p = 0.0001). Peak cardiac index (4.6 ± 2.1 vs. 5.1 ± 1.9 liters/min/m2, p = 0.14), patient acceptance score (4.2 ± 0.7 vs. 3.8 ± 1.3, p = 0.17) and study duration (14.2 ± 9.3 vs. 13.3 ± 3.3 min, p = 0.59) were similar. Recovery time (7.1 ± 7.6 vs. 16.2 ± 15.9 min, p = 0.0003) and interpretation time (9.1 ± 2.8 vs. 13.5 ± 4.4 min, p = 0.0001) were shorter for TAPSE than for DSE.CONCLUSIONSTwo-stage TAPSE permits rapid evaluation of cardiac patients. Peak cardiac index and patient acceptance scores were similar for TAPSE and DSE. Ischemia was detected more often with TAPSE; this result was attributed to the higher peak heart rate obtained with this protocol.

Room 302, 10/18/2000 2: 00 PM - 3: 30 PM (PD) Reproducibility of Regional Wall Motion Analysis during Intraoperative Low Dose Dobutamine Stress Echocardiography (DSE) in CABG Surgery

<b>Room 302, 10/18/2000 2: 00 PM - 3: 30 PM (PD) Reproducibility of Regional Wall Motion Analysis during Intraoperative Low Dose Dobutamine Stress Echocardiography (DSE) in CABG Surgery</b>

Intraoperative detection of segmental wall motion abnormalities with transesophageal echocardiography

To compare two methods of analysis of regional wall-motion (RWM) using transesophageal echocardiography (TEE). Thirty patients undergoing coronary artery bypass surgery were studied. The transgastric short axis view at the mid-papillary level was recorded before and after cardiopulmonary bypass. All images were reviewed by an anesthesiologist trained in TEE and an echocardiographer. Regional wall motion was graded: 1 normal, 2 hypokinetic, 3 akinetic, and 4 dyskinetic. The left ventricle was evaluated according to the guidelines of the American Society of Echocardiography using 6-segment, and 4-segment models. Agreement between observers (interobservers), and for one observer at two different moments (intraobservers), for grading each segment was defined as RWM abnormality scores within 1 grade. A wall-motion score index (WMSI), which is the sum of individual scores divided by the number of segments visualized, was calculated. A Bland Altman analysis was used to assess interobserver variability. Agreement between observers occurred in 96% and 94% of the examined segments, using 4- and 6-segment models respectively. Intraobserver agreement was 99% and 97% for the 4- and 6-segment models. The mean differences (bias) of the interobserver variability in grading the segments were 0.04 +/- 0.79 and 0 +/- 0.72 using a 4- or 6-segment model. The mean difference of the interobserver variability in WMSI were -0.05 +/- 0.42 and 0.05 +/- 0.37 using a 4- or a 6-segment model. Both methods, using either a 4- or a 6-segment model, result in a high intraobserver and interobserver agreement, and a low interobserver variability.

Diagnostic criteria for detection of postinfarction ischemia by quantitative analysis of stepwise dobutamine radionuclide ventriculography

Background: Application of the traditional diagnostic criteria validated for exercise testing may be inappropriate when dobutamine infusion is associated with radionuclide ventriculography (RNV). The objective of this study was to establish appropriate diagnostic criteria for evaluation of dobutamine stress testing with RNV for the detection of early postinfarction ischemia. Methods: RNV was performed at baseline and during dobutamine infusion in 10 control subjects and in 30 patients who were studied within 1 week after uncomplicated myocardial infarction. Several quantitative parameters including left ventricular ejection fraction (EF), regional EF, and absolute change in global and regional EF were tested. In addition, regional wall-motion changes were scored by visual analysis. The limit of normal response for each quantitative parameter was defined as the 95th percentile of the distribution observed in control subjects. On the basis of predischarge clinical evaluation and exercise stress testing, patients were grouped as having evidence of residual ischemia (group 1, 15 patients) or no evidence of ischemia (group 2, 15 patients). Sensitivity, specificity, and accuracy in the detection of postinfarction ischemia were calculated for each parameter, and empiric receiver-operating characteristic curves were generated. Results: The limits of the normal response to dobutamine infusion in the control subjects were found to be a 7.5% and a 12.5% increase in global EF at low and high dose, respectively. Median baseline EF was significantly lower in patients than in control subjects (Mann-Whitney U test: P < .001). There were no differences in resting EF between group 1 and group 2 patients. However, median high-dose EF and increase in EF were significantly lower in group 1 as compared with group 2 patients (56% vs 72% and 5% vs 17%, respectively; Mann-Whitney U test: P < .0001 for both). A biphasic (up-and-down) response with initial increase at low dose followed by decrease or no change in EF at high dose was observed in 66% of group 1 patients and only in 13% of group 2 subjects. The best criterion for detection of postinfarction ischemia was a change of <12.5% in global EF at high-dose dobutamine infusion, with 80% predictive accuracy. The traditional criterion, a change of <5% or a decrease in EF, yielded an accuracy of only 63%. The association of a change of <12.5% with a biphasic response increased accuracy to 87%, with a sensitivity of 93% and a specificity of 80%. Quantitative regional wall motion analysis showed greater diagnostic accuracy than visual wall motion scoring (83% vs 70%). Conclusions: Application of appropriate criteria and stepwise quantitative analysis of RNV during dobutamine infusion may increase accuracy in the detection of early postinfarction ischemia.

Myocardial Velocity Gradient Assessed by a Tissue Doppler Imaging Technique.

Although tissue Doppler imaging (TDI) is a promising technique for quantitative regional left ventricular wall motion analysis, Doppler angle of incidence and translational motion of the heart influence the velocity measurement by TDI because, in principle, TDI detects the velocity against the transducer. Myocardial velocity gradient (MVG) is derived from TDI as the slope of the regression line for a transmural velocity profile across the myocardial wall, which reflects regional wall thickening and thinning dynamics. Thus, regional diastolic and systolic function may be quantified by using MVG. MVG is also validated to be independent of the translational motion both theoretically and clinically. MVG may therefore be used as an indicator of regional wall motion even under such a condition that the translational motion of the heart cannot be neglected. Our preliminary experience suggests that the quantitative and objective nature of MVG enhances the diagnostic power of stress echocardiography. Further development of the automated, real time processing system and the algorithm for the apical approaches should be awaited for the practical approaches of MVG to be applied to daily clinical practice.

Usefulness of color kinesis imaging for evaluation of regional right ventricular wall motion in patients with surgically repaired tetralogy of Fallot

We evaluated regional right ventricular wall motion during systole in patients with surgically repaired tetralogy of Fallot (TOF) using color kinesis imaging. Color kinesis images were obtained in a subcostal sagittal view from 19 patients with repaired TOF (TOF group), aged 3 to 5 years, and 20 age-matched normal subjects (control group). For regional wall motion analysis, the endocardial motion distance and the fractional area change (FAC) were calculated for 6 segments obtained from color kinesis images. The endocardial inward excursion distances and the FACs in the upper, middle, and lower posterior segments of the TOF group were significantly greater than those of the control group (p < 0.01 for each segment). The upper anterior segment showed significantly reduced inward excursion distance and FAC in the TOF group than in the control group (p < 0.01, both). The dyskinetic outward excursion distances of the middle and lower posterior segments were significantly lower in the TOF group than in the control group (p < 0.01, both). In the upper and middle anterior segments, the endocardial outward excursion distances were significantly higher in the TOF group than in the control group (p < 0.01 and 0.05). Correlation between right ventriculographic and color kinesis measurements was excellent (y = 1.14x − 1.30, r = 0.87 for the endocardial inward excursion, and y = 1.03x + 0.56, r = 0.91 for the FAC). In conclusion, color kinesis is a useful method for assessing regional right ventricular wall motion. Segmental analysis of color kinesis images provides accurate, automated, and quantitative diagnosis of regional right ventricular wall motion abnormalities in patients with surgically repaired TOF.

Myocardial tagging for the analysis left ventricular function.

Based on our measurements following observations were made: Myocardial tagging makes an accurate regional wall motion analysis and the assessment of cardiac rotation possible and, thus, allow new insight into the mechanical function of the heart.

Does Positive End-Expiratory Pressure Ventilation Improve Left Ventricular Function?: A Comparative Study by Transesophageal Echocardiography in Cardiac and Noncardiac Patients

Positive end-expiratory pressure (PEEP) has been proposed to improve cardiac output in patients with left ventricular (LV) dysfunction. This study was designed to compare quantitative global and regional LV performance in response to PEEP in patients with normal and poor LV function. A prospective clinical trial. Adult medical ICU in a university hospital. Twelve critically ill patients requiring respiratory support and divided into two groups according to baseline transesophageal echocardiographic (TEE) measurements: normal LV dimensions and fractional area of contraction (FAC=61+/-5%) (n=7) and dilated cardiomyopathy with reduced FAC (21+/-1%) (n=5). All patients were studied when two successive levels of PEEP (best PEEP as the highest value of respiratory compliance and high PEEP as best PEEP+10 cm H2O) were applied. Global systolic LV performance and quantitative regional wall motion analysis performed by the centerline method were assessed on the TEE transgastric short-axis view. End-systolic wall stress (ESWS) was used as a reliable indication of LV afterload. PEEP reduced LV dimensions asymmetrically in both groups of patients and septolateral diameter significantly decreased without affecting global LV systolic performance. Additionally, high PEEP produced a significant impairment in septal kinetics as evidenced by the centerline method. High PEEP also decreased ESWS for all patients (-27% in normal group and -23% in cardiac group, p<0.05) without significant improvement in global systolic LV performance (FAC: +2% in normal group and +0% in cardiac group; not significant). PEEP cannot be recommended routinely to improve LV performance in patients with severe dilated cardiomyopathy.

Intraoperative Evaluation of Segmental Wall Motion Abnormalities According to the Guidelines of the American Society of Echocardiography

Intro.: The most commonly used imaging plane for ischemia monitoring with transesophageal echocardiography (TEE) is the transgastric short axis view at the level of the mid-papillary muscles. While the majority of studies evaluating intraoperative regional wall motion abnormalities (RWMA) used a four segments model [1] at the mid papillary level, the American Society of Echocardiographer (ASE) has published guidelines describing a 16 segments model of the left ventricle, including 6 segments at the mid papillary level [2]. These guidelines should be used to properly define the segments of the myocardium of interest. The goal of this study was to compare 2 methods of analysis of regional wall motion (RWM) [1,2] when used by an anesthesiologist trained in TEE and an echocardiographer. Methods: The transgastric short axis view using TEE at the mid-papillary level was monitored during coronary artery bypass grafting in 30 patients, before and after the cardiopulmonary bypass. All images were recorded on VHS tape and reviewed independently by an anesthesiologist trained in TEE and an echocardiographer. RWM was graded as follow: 1-normal, 2-hypokinetic, 3-akinetic, and 4-dyskinetic. The left ventricle at the mid-papillary level was first evaluated according to a 6 segments model: inferior, infero-lateral, antero-lateral, anterior, antero-septal, and infero-septal [2]. We also evaluated the left ventricle according to a 4 segments model: inferior, lateral, anterior, and septal [1]. Agreement between observers for each segment was defined as RWMAs score within 1 grade. We also calculated a wall motion score index (WMSI) which is the sum of individual scores divided by the number of segments visualized. A Bland-Altmann analysis was used to assess interobserver variability (bias). Results: A total of 480 segments were analyzed. Using a 4 segments model, agreement between the anesthesiologist and the echocardiographer concurred in 96 % of the examined segments (score within 1 grade). When using the 6 segments model, agreement reached 94%. Using bias analysis (Bland-Altman), the mean differences (bias) of the interobserver variability in grading the segments were 0.04 +/- 0.79 and 0 +/- 0.72 using a four or a six segments model. The mean differences of the observer variability in Wall Motion Score Index (WMSI) were -0.05 +/- 0.42 and 0.05 +/- 0.37 using a four or a six segments model. Discussion: The use of the guidelines of the ASE [2] to assess RWMAs has the advantage of uniformity between anesthesiologists and other echocardiographers. Using these guidelines, we found a high degree of agreement between an anesthesiologist trained in TEE and an echocardiographer using either a four or a six segments model. The precision between the observers was better (smaller standard deviations) when using the WMSI than the RWMAs. This could be secondary to interobserver variation in segment location which will be minimized by calculating WMSI compared with the score obtained using RWMAs.

Prolonged Myocardial Hibernation Exacerbates Cardiomyocyte Degeneration and Impairs Recovery of Function After Revascularization

Objectives. We sought to define the effects of time on contractile function, morphology and functional recovery after coronary revascularization in patients with dysfunctional but viable (hibernating) myocardium.Background. Functional recovery after coronary artery bypass graft surgery in patients with chronic myocardial hibernation is incomplete or delayed. The proposed cause is a progressive temporal degeneration of cardiomyocytes.Methods. In 32 patients with multivessel coronary disease, regional wall motion analysis was performed in hypoperfused but metabolically active areas before and 6 months after bypass surgery. During bypass surgery, transmural biopsy samples were obtained from the center of the hypokinetic zone for light and electron microscopic analyses. The proposed duration of myocardial hibernation was retrospectively assessed.Results. Patients with a subacute hibernating condition (<50 days) demonstrated a higher preoperative ejection fraction (EF, 50 ± 8%), and a better preserved wall motion (WM) in the supraapical wall (−1.4 ± 0.4) than did patients with intermediate-term (>50 days, EF 37 ± 9%, p < 0.05; WM −2.4 ± 1.5, p = 0.08) or chronic (>6 months, EF 40 ± 14%, WM −2.7 ± 0.9, p < 0.005) ischemia. Structural degeneration correlated with the duration of ischemia (r = 0.56, p < 0.05). Postoperative recovery of function was enhanced in patients with a short history of hibernation compared with patients with an intermediate-term or chronic condition (EF 60 ± 10% vs. 40 ± 10%, p < 0.001, and vs. 47 ± 14%, p < 0.05).Conclusions. Hibernating myocardium exhibits time-dependent deterioration due to progressive structural degeneration with enhanced fibrosis. Early revascularization should be attempted to salvage the jeopardized tissue and improve postoperative outcome.

Comparison of Exercise Electron Beam Computed Tomography and Sestamibi in the Evaluation of Coronary Artery Disease

This blinded, single center study prospectively compares exercise electron beam computed tomography (EBCT) with stress technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) in 33 patients undergoing coronary angiography for evaluation of chest pain. Patients undergoing routine cardiac catheterization for the diagnosis of chest pain were imaged at rest using EBCT. Patients exercised on a semi-supine ergometer, and exercise EBCT was immediately followed by injection of Tc-99m sestamibi for assessment of myocardial ischemia. At peak exercise, Tc-99m SPECT, followed immediately by nonionic contrast material, was injected intravenously to directly compare these 2 imaging techniques. Patients were reimaged with Tc-99m SPECT at rest 24 to 48 hours after stress. Exercise EBCT, which was analyzed using a global ejection fraction measure, had a sensitivity of 81% and a specificity of 76%, compared with angiography. Using the development of a new regional wall motion abnormality as evidence of obstructive coronary artery disease (CAD), EBCT yielded a specificity of 100% and a sensitivity of 88%. Reversible perfusion defects identified by SPECT, as evidence of obstructive CAD, revealed a sensitivity of 75% and a specificity of 71%. The specificity of regional wall motion analysis by EBCT was significantly better than SPECT (p <0.01) in this population. This study demonstrates regional wall motion assessed by EBCT to be as sensitive and more specific than SPECT myocardial perfusion imaging in identifying obstructive CAD as defined by angiography.

New method for on-line quantitative analysis of regional wall motion using color kinesis

New method for on-line quantitative analysis of regional wall motion using color kinesis

Pediatric stress echocardiography

In investigating cardiovascular dynamics, echocardiography performed during stress is superior to resting echocardiography because it provides information which more accurately mimics a child's typical active state and it is often capable of detecting disease states earlier. Specifically, it is useful in the evaluation for ischemia in children with coronary artery disease (e.g. Kawasaki disease, cardiac transplant vasculopathy, and congenital anomalies) and how hemodynamics in congenital heart disease (e.g. aortic stenosis, hypertrophic cardiomyopathy) change during an active cardiovascular state. Dobutamine is the ideal stressing agent because it does not share some of the limitations of exercise and the other pharmacologic agents. For an evaluation of ischemia, dobutamine is administered in increasing doses at 5-min intervals until a heart rate of 85% of age-related maximal heart rate is attained. Echocardiography is performed throughout the test but particular emphasis is placed on four conditions (rest, low dose dobutamine, peak heart rate, and recovery). Ischemia is identified by a new or worsening regional wall motion abnormality. The site of a regional wall motion abnormality localizes the diseased coronary artery. Analysis of regional wall motion is particularly difficult and requires additional training beyond that of a traditional pediatric cardiologist. For a stress evaluation investigating hemodynamics other than ischemia (e.g. aortic stenosis), dobutamine is administered in increasing doses until symptoms develop or hemodynamics become severe (e.g. severe aortic stenosis gradient). Usually less dobutamine is required before these conditions are met. Stress echocardiography is a valuable adjunct to the pediatric echocardiographic examination. Since children are rarely sedentary, stress echocardiography provides an opportunity to view the pediatric heart through a more physiologic window.

Regional wall motion during pacing for hypertrophic obstructive cardiomyopathy.

In order to assess the influence of right ventricular stimulation on LV contraction sequence in hypertrophic obstructive cardiomyopathy (HOCM), we performed a regional wall-motion analysis of the left ventricle by comparing normal His-Purkinje activation to pacing from the right ventricular apex. In 9 patients (5 males and 4 females, mean age 61 +/- 9 years) assessed after a mean pacing period of 12 weeks (range 7-24 weeks), AV sequential pacing induced a 52% reduction in maximal pressure gradient from 76 +/- 36 to 40 +/- 28 mmHg (P < 0.01) as determined by Doppler examination. Regional wall-motion analysis of the left ventricle was computed from digitized two-dimensional echocardiographic images by means of the area shrinking method. Pacing induced a significant reduction of total septal area shrinking from 25% +/- 17% to 12% +/- 17% (P < 0.005). A tendency toward paradoxical septal motion was observed in one patient only. The apex showed no significant variation. A 6% increase in area shrinking was observed at the posterior wall and lateral free wall, from 38% +/- 13% to 43% +/- 10% (P < 0.05). Pacing did not significantly alter the global ejection fraction. A direct correlation between the magnitude of subaortic pressure gradient reduction and that of septal motion changes was found in a majority of patients. In conclusion, dual chamber pacing reduces septal wall motion in patients with HOCM obstructive cardiomyopathy. This might be one of the mechanisms involved in the reduction of LV outflow tract obstruction.

Regional wall motion analysis by dobutamine stress echocardiography to distinguish between ischemic and nonischemic dilated cardiomyopathy: C. Vigna, A. Russo, V. De Rito, G.P. Perna, M. Testa, A. Lombardo, P. Lanna, T. Langialonga, H.P. Salvatori, R. Fanelli, F. Loperfido. Policlinico A. Gemelli, Istituto di Cardiologia, Universita Cattolica “Sacra Cuore,” Rome, Italy. Am Heart J 1996;131: 537–43

Regional wall motion analysis by dobutamine stress echocardiography to distinguish between ischemic and nonischemic dilated cardiomyopathy: C. Vigna, A. Russo, V. De Rito, G.P. Perna, M. Testa, A. Lombardo, P. Lanna, T. Langialonga, H.P. Salvatori, R. Fanelli, F. Loperfido. Policlinico A. Gemelli, Istituto di Cardiologia, Universita Cattolica “Sacra Cuore,” Rome, Italy. Am Heart J 1996;131: 537–43

Transposition of the great arteries

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Right and left ventricular function assessed by regional wall motion analysis in patients with tetralogy of Fallot

We studied pre- and postoperative regional right and left ventricular wall motion and global ejection fraction in 18 patients with tetralogy of Fallot who had successful repair, and compared these values to those of patients with a history of Kawasaki disease as controls. Right ventricular ejection fraction was significantly lower in the preoperative group (52±4%) than that in the control group (57±4%), and that in the postoperative state (49±4%) was significantly lower than those in the control and preoperative groups. Left ventricular ejection fraction was significantly lower in the preoperative group (56±7%) than that in the control group (61±5%), while that in the postoperative state (64±6%) was significantly higher than those in the control and preoperative groups. Regional ventricular wall motion analysis revealed that shortening fractions in the tricuspid valve region were reduced in the preoperative patients and were persistent even after successful repair; those in the right ventricular outflow tract region were decreased after the correction. Regional left ventricular wall motion showed that shortening fractions in the anterolateral region were improved after the correction. We conclude that right ventricular dysfunction was present in the preoperative patients with tetralogy of Fallot and was persistent even after total correction.

Binary reconstruction of the heart chambers from biplane angiographic image sequences

The aim of this work is the three-dimensional (3-D) reconstruction of the left or right heart chamber from digital biplane angiograms. The approach used, the binary reconstruction, exploits the density information of subtracted ventriculograms from two orthogonal views in addition to the ventricular contours. The ambiguity of the problem is largely reduced by incorporating a priori knowledge of human ventricles. A model-based reconstruction program is described that is applicable to routinely acquired biplane ventriculographic studies. Prior to reconstruction, several geometric and densitometric imaging errors are corrected. The finding of corresponding density profiles and anatomical landmarks is supported by a biplane image pairing procedure that takes the movement of the gantry system into account. Absolute measurements are based on geometric isocenter calibration and a slice-wise density calibration technique. The reconstructed ventricles allow 3-D visualization and regional wall motion analysis independently of the gantry setting. The method is applied to clinical angiograms and tested in left- and right-ventricular phantoms yielding a well shape conformity even with few model information. The results indicate that volumes of binary reconstructed ventricles are less projection-dependent compared to volume data derived by purely contour-based methods. A limitation is that the heart chamber must not be superimposed by other dye-filled structures in both projections.

Myocardial dysfunction after resuscitation from cardiac arrest: An example of global myocardial stunning

Objectives. This study investigated the effect of prolonged cardiac arrest and subsequent cardiopulmonary resuscitation on left ventricular systolic and diastolic function.Background. Cardiac arrest from ventricular fibrillation results in cessation of forward blood flow, including myocardial blood flow. During cardiopulmonary resuscitation, myocardial blood flow remains suboptimal. Once the heart is defibrillated and successful resuscitation achieved, reversible myocardial dysfunction, or “stunning,” may occur. The magnitude and time course of myocardial stunning from cardiac arrest is unknown.Methods. Twenty-eight domestic swine (26 ± 1 kg) were studied with both invasive and noninvasive measurements of ventricular function before and after 10 or 15 min of untreated cardiac arrest. Contrast left ventriculograms, ventricular pressures, cardiac output, isovolumetric relaxation time (tau) and transthoracic Doppler-echocardiographic studies were obtained.Results. Twenty-three of 28 animals were successfully resuscitated and postresuscitation data obtained. Left ventricular ejection fraction showed a significant reduction 30 min after resuscitation (p < 0.05). Regional wall motion analysis revealed diffuse, global left ventricular systolic dysfunction. Left ventricular end-diastolic pressure increased significantly in the postresuscitation period (p < 0.05). Isovolumetric relaxation time (tau) was significantly increased over baseline by 2 h after resuscitation (p < 0.05). Similar findings were noted with the Doppler-echocardiographic analysis, including a reduction in fractional shortening (p <0.05), a reduction in mitral valve deceleration time (p < 0.05) and an increase in left ventricular isovolumetric relaxation time in 5 h after resuscitation (p < 0.05). By 24 h, these invasive and noninvasive variables of systolic and diastolic left ventricular function had begun to improve. At 48 h, all measures of left ventricular function had returned to baseline levels.Conclusions. Myocardial systolic and diastolic dysfunction is severe after 10 to 15 min of untreated cardiac arrest and successful resuscitation. Full recovery of this postresuscitation myocardial stunning is seen by 48 h in this experimental model of ventricular fibrillation cardiac arrest.