Cardiac Wall Motion Research Articles

Heart injury in head-injured adolescents.

Of 19 adolescents (ages 10-18) admitted consecutively because of major blunt-impact trauma, 15 had head injuries (Glasgow coma scales 4-15). Eight had cardiac injury (42%), as demonstrated by cardiac wall-motion studies utilizing ECG-gated radionuclide angiography. Of the head-injured patients, 7 had cardiac injury (47%), and of these, one died in cardiac shock. Significant cardiac injury is known both experimentally and clinically to escape detection by conventional methods and a compromised cardiac output may bode ill for a damaged brain if cerebral perfusion pressure is in jeopardy.

Cardiac evaluation following heart injury.

Both penetrating and blunt cardiac injuries require urgent management. Delayed sequelae and complications have been reported to occur in 4 to 56% of survivors and frequently required secondary surgical corrections. Between January 1980 and June 1984, 204 patients presented with heart injuries. One hundred twenty-eight of these patients survived. Of the 90 undergoing cardiorrhaphy in the operating room, 78 survived. Two-dimensional (2-D) and pulsed-Doppler echocardiography (echo) and/or cardiac catheterization were performed in 40 patients for suspected significant residual injury. Eight of the 40 required secondary cardiac operations. Two-dimensional echo demonstrated pericardial effusion, abnormal chamber enlargement, abnormal cardiac wall motion, intracardiac missile, and intracardiac and pleural thrombus. Pulsed-Doppler findings included ventricular septal defect, tricuspid insufficiency and right ventricular turbulence secondary to arteriovenous fistulae. Cardiac catheterization detected lesions undetected by 2-D echo in one patient with a gunshot wound. It is concluded that in the absence of cardiac bullets seen on routine chest X-ray, 2-D with pulsed-Doppler echo is an excellent screening technique. With a positive echo study or a residual bullet overlying the cardiac silhouette, cardiac catheterization is indicated in selected patients.

Computed Tomography of the Heart and Great Vessels: Present and Future

Computed tomography (CT) has emerged as a new imaging method for the diagnosis and evaluation of cardiovascular disease. With CT body scanners and contrast enhancement, evaluation of aortic dissections and aneurysms, coronary bypass graft patency, cardiovascular thrombus, cardiac tumors, and pericardial disease is possible. On occasion, this technique provides clinically useful information that is not available with other imaging methods. Electrocardiographic gating retrospectively or prospectively improves the image resolution of CT scans, but a new ultrafast CT scanner with a scan time of 30 to 50 milliseconds offers the greatest promise for expanding the application of the technology for cardiovascular diagnosis. Accurate measurement of cardiac chamber volume, mass, wall motion, and wall thickening will be feasible. Ultrafast CT scanning also shows great promise for the measurement of myocardial infarct size and regional myocardial blood flow.

Coronary Artery Bypass Graft Surgery: Relative Efficacy of Initial Proximal versus Distal Anastomoses

Controversy exists concerning the most appropriate sequence of anastomoses in coronary artery bypass grafting (CABG) procedures. While the more commonly employed method of distal coronary anastomoses first has withstood a long clinical experience, a recent study and several cardiac surgical groups have suggested that construction of the proximal anastomoses first offers certain advantages. In 30 patients undergoing CABG, we performed a prospective, randomized trial comparing both techniques. Relative efficacy was assessed by hemodynamic, radionuclide, electrocardiographic, enzymatic, thermographic, and clinical evaluation. The length of cardiopulmonary bypass was longer in the group having the distal anastomoses done first. Myocardial temperature mapping was similar between groups. Hemodynamic changes, including cardiac output, ejection fraction, and regional wall motion, were nearly identical between the groups. The incidence of myocardial damage reflected by levels of myocardial-specific isoenzymes (serum CK-MB) and electrocardiographic changes was also similar. In conclusion, the sequence of anastomoses is not critical in routine CABG operations. However, we speculate that each technique may have certain advantages under different clinical circumstances found on occasion. Ideally, each method should be part of the coronary surgeon's armamentarium.

Techniques, Diagnostics, and Advances in Nuclear Cardiology

More than two thirds of this book is directed to the novice and provides a clear, detailed presentation of the technical aspects and diagnostic uses of the various studies available to investigate cardiac functions and myocardial perfusion. Unfortunately, the later chapters are uneven in the quality of their descriptions of advances in nuclear cardiology. For example, the book does not give adequate coverage to parametric images in the evaluation of cardiac wall motion and makes no mention of the current clinical use of Fourier analysis imaging, although software for this is now available through most computer companies. In the discussion on myocardial perfusion, only a bare mention is given to seven-pinhole tomography, rotating slant-hole tomography, or single-photon-emission computed tomography. An interesting chapter on positron emission transaxial tomographic imaging is followed by a superficial discussion of nuclear magnetic resonance, which does not include cardiac imaging. These shortcomings do not take away

Sequence of occurrence of abnormal regional cardiac function, global pump function and electrocardiogram after brief ligation and reperfusion of a coronary artery.

The following results were obtained. During brief ligation of the coronary artery, a change in the cardiac wall motion appeared as the first abnormality of the CMG. Succeedingly, epicardial ECG changes were recognized, and lastly, changes of dP/dt appeared. After reperfusion of the coronary artery, dP/dt was quickly normalized, followed by restoration of ST elevation. Cardiac motion, measured by CMG, was the last abnormality to improve.

Left ventricular wall motion: Its dynamic transmural characteristics

Cardiac wall motion has been studied extensively. It is usually determined by indirect two-dimensional measurements for the true three-dimensional (3D) motion with its specific speed and direction. Errors are also introduced by using internally fixed reference systems and by the inability to identify precise points on the heart wall during the cardiac cycle. Because of these limitations, the endocardial and epicardial wall motion and their relationship are still unclear. This study was designed to assess endocardial and epicardial wall motion by measuring the direction and speed of implanted markers in an externally fixed 3D coordinate system. Fifty-seven pairs of endocardial and epicardial metallic markers were placed at anterior, lateral, posterior, basal, and apical regions of the left ventricles of 14 normal mongrel dogs. Biplane cineradiographs were performed at 50 frames/sec, and the 3D motions of the markers were analyzed using a specially designed computer system. It was found that the speeds, directions, displacements, and phases of the movements of corresponding endocardial and epicardial points were highly correlated. The correlation coefficients were 0.77 to 0.95 for the mean directions, 0.61 to 0.96 for the mean speeds, and 0.59 to 0.96 for the mean displacements at various regions of the heart, and the periodic movements of the endocardium and epicardium were always in phase. The mean epicardial speeds and displacements are fixed proportions (approximately 70%) of the mean endocardial speeds and displacements despite the differences in absolute values between regions in the same dog and the same regions in different dogs. The correlation coefficients for endocardial and epicardial instantaneous speeds, directions, and velocities ranged from 0.68 to 0.83, 0.81 to 0.88, and 0.77 to 0.86, respectively, for different regions of the heart. The correlation coefficients were significant for both the mean values and the instantaneous values. Thus, when only fixed epicardial points are accessible for wall motion measurements in clinical situations, it is possible to infer the endocardial motion from the epicardial motion.

Dual Gated Nuclear Cardiac Images

A data acquisition system has been developed to collect camera events simultaneously with continually digitized electrocardiograph signals and respiratory flow measurements. Software processing of the list mode data creates more precisely gated cardiac frames. Additionally, motion blur due to heart movement during breathing is reduced by selecting events within a specific respiratory phase. Thallium myocardium images of a healthy volunteer show increased definition. This technique of combined cardiac and respiratory gating has the potential of improving the detectability of small lesions, and the characterization of cardiac wall motion.

Collateral function in early acute myocardial infarction

The role of the collateral circulation < 6 hours after the onset of acute myocardial infarction (MI) was evaluated in 34 consecutive patients without previous MI. There were 19 patients with and 15 without collaterals. The group was subdivided into those with nonjeopardized collaterals (group A, 14 patients) and those with jeopardized collaterals (group B, 5 patients), and the group without collaterals into those with partially obstructed coronary arteries (group C, 5 patients) and those with totally obstructed coronary arteries (group D, 10 patients). These groups had similar sites of coronary stenoses and MI. Eleven of 14 collaterals in group A were poor, but MI mass measured by peak creatine kinase (CK) was smaller in group A than in group B (p < 0.01) or group D (p < 0.01), and cardiac function was significantly better in group A than in group D (cardiac index, p < 0.05; stroke index, p < 0.01; ejection fraction, p < 0.01; regional wall motion, p < 0.01). Group C was not statistically different from group A in myocardial function and CK. Group B was similar to group D in MI mass and cardiac function (cardiac index, stroke index, ejection fraction and regional wall motion). Thus, patients with nonjeopardized collaterals and those with partially obstructed coronary arteries had less myocardial damage and better cardiac function than did those with jeopardized collaterals and those with totally obstructed coronary arteries. A nonjeopardized collateral circulation may play a role in limiting MI mass and preserving myocardial function in the early stages of acute MI.

Methods for evaluating cardiac wall motion in three dimensions using bifurcation points of the coronary arterial tree.

An accurate three-dimensional (3D) representation of heart wall motion would be an important means of evaluating cardiac function. To accomplish this, we have developed an interactive computer graphics system designed to enter the time-dependent 3D positions of bifurcations of the coronary arterial tree. These bifurcations are precise markers of the epicardial surface, and their motions accurately represent the motion of the underlying heart wall. We demonstrate techniques for calculating local wall motion, including displacement and velocity, for determining a time-dependent center-of-contraction point towards which the epicardium tends to move and for tracking the mechanical contraction wave using cross-correlation methods. We have applied these techniques to study seven patients with normal left ventriculograms and coronary arteriograms. We have found these methods to be generally applicable and to provide information not obtainable without 3D analysis.

Graphics methods for tracking three-dimensional heart wall motion

An analysis of heart wall motion requires that specific points on the wall be identified and their movements tracked in three dimensions over several heart beats. A method to reconstruct time-dependent 3D coordinates from any two or more perspective views has been developed. We have used this method to determine accurately the 3D dynamics of bifurcation points of the coronary arteries or surgically implanted markers by tracking their projections in both views of a biplane coronary cineangiogram. The tracking operation is aided by a sophisticated interactive computer system which superimposes an animated graphics display onto the film image. This allows entries to be checked and corrected immediately. The most powerful tool provided by the graphics system is the ability to display the backprojections of positions from one view as auxiliary lines across the other view on which the projection of the point of interest must lie. We provide some examples of cardiac wall motion measures we have made using this system.

Assessment of cardiac wall motion with the ejection fraction image: a comparison with contrast left ventriculography.

Twenty patients with ischemic heart disease were studied with biplane contrast left ventriculography and gated bloob pool scans. An ejection fraction (EF) image was calculated from each gated blood pool scan. The EF image and contrast ventriculograms were divided into three regions and seven segments respectively. The sites of asynergy observed in each study were compared. Segments two, three and six of the contrast ventriculogram corresponded to the anteroseptal and inferoapical regions of the EF image, but it was difficult to differentiate between these segments on the EF image. Segments three and four corresponded to the inferoapical region and segments five and seven corresponded to the posterolateral region. Diffuse asynergy with a low EF (less than 30%) causes a large defect on the EF image. The mean regional EF obtained from the EF image correlated well with the EF calculated from the left ventricular volume curve (n = 50, r = 0.94).

Digital Boundary Detection Techniques For The Analysis Of Gated Cardiac Scintigrams

Boundary detection in conventional nuclear medicine scintigrams is often difficult for several reasons. First, scintigrams generally have a low signal-to-noise ratio. Second, edge structures are poorly defined because of the low resolution of gamma ray cameras; and finally, edge contrast is usually reduced by foreground and background activity. In this paper we report on heuristic approaches we have taken to solve these problems and to develop programs for the display of cardiac wall motion and for the automatic determination of left ventricular ejection fraction. Our approach to processing cardiac scintigrams entails several steps: smoothing, edge enhancement, and contour extraction. We discuss each of these steps in light of the goal of producing cardiac boundaries which are spatially and temporally smooth and continuous. Boundary detection results are presented for some selected clinical images.

Factors determining the waveform of cardiokymography.

The mechanism of detecting the cardiac wall motion by Cardiokymography (CKG) using a sensing coil was studied by the following experiments. 1) The precordial maps of CKG were recorded on 3 subjects. When the surface movement of the chest was eliminated by a piece of acrylic board in each subject, the amplitude of CKG was reduced to average of 22.7±2.5% of the initial amplitude (p<0.01). 2) As the content of salt was increased in water and blood above the probe, the oscillation frequency dropped slightly at first, then it went up beyond the initial value. 3) When an artificial pneumothorax was made in a dog, the amplitude was reduced. Then, by the application of an acrylic board, the wave form became flat. 4) CKG could not detect the movement of the resected canine heart containing blood in a normal saline solution. These data indicate that the capacitance was the main determinant of oscillation frequency in man and that the most significant factor of the wave form was the surface movement of the chest.

Detection of regional cardiac wall motion abnormalities in myocardial infarction by cardiac wall kymography.

The new system of cardiac wall kymography was proposed based on the results with our modified device. The cardiac wall motion kymography taken from a portion of the precordial area was examined for its ability to detect wall motion abnormalities. Furthermore, the 3 dimensional graphic display of the cardiac wall kymogram map was attempted by computer. This new approach looks promising because of the enhanced ability to recognize cardiac wall motion abnormalities in myocardial infarction.

Differentiation of posterior myocardial infarction from right ventricular hypertrophy and normal anterior loop by echocardiography.

The differentiation of posterobasal myocardial infarction (PMI) from either right ventricular hypertrophy (RVH) or normal subjects displaying an anterior loop (AL) by electrocardiography (ECG) or vectorcardiography (VCG) is difficult. M-mode echocardiography (echo) via the anterior and subxiphoid methods has been helpful in defining cardiac chamber size and wall motion abnormalities. We tested whether this relatively more direct method would better separate these entities compared with the other two techniques. ECG and VCG using established criteria failed to distinguish the three conditions effectively. By echo, distinguishing characteristics were observed in each of the groups. Thus, right ventricular diastolic dimension and wall thickness were significantly increased only in the RVH group, echo dimensions and wall motion were normal in the AL group and the posterior left ventricular systolic thickening response and ejection phase indices were significantly reduced only by the subxiphoid method in the PMI group. To test the specificity of the latter finding, posterior wall motion in three infarction groups (posterior, combined posteroinferior and inferior) were examined and suggested that the target of the subxiphoid beam focuses on a more superior posterobasal left ventricular segment than the anteriorly placed transducer. Echocardiography can differentiate PMI from either RVH or AL more directly than ECG or VCG, and may be of practical clinical importance.

Methylprednisolone treatment in acute myocardial infarction: Effect on regional and global myocardial function

The effects of methylprednisolone treatment on acute myocardial ischemia were studied in nine closed chest dogs. After 1 hour of proximal occlusion of the left anterior descending coronary artery, an intravenous bolus injection (50 mg/kg body weight) of methylprednisolone was administered and its effects studied during an additional 2 hours of occlusion. After 2 hours of treatment the following significant mean alterations from levels after 1 hour of occlusion were noted: an increase of 16.7 percent in heart rate and decreases of 23 percent in left ventricular end-diastolic pressure, 32 percent in stroke volume, 14 percent in cardiac output and 37 percent in stroke work. Peak systolic pressure, maximal rate of rise of left ventricular pressure (dP/dt), left ventricular end-diastolic volume, systemic vascular resistance and coronary sinus blood flow changed less than 10 percent. Ejection fraction and regional cardiac wall motion were not improved. Metabolic dysfunction of the coronary-occluded myocardium, revealed by regional lactate as well as potassium derangements, persisted throughout the 2 hour treatment period. Comparison of these results with equivalent data from an untreated series of nine dogs with 3 hours of occlusion demonstrated no improvement in the treated series. Methylprednisolone failed to restore regional cardiac metabolic and mechanical function, and treatment was associated with a further rise in S-T segment elevations. Administration of methylprednisolone after 1 hour of proximal left anterior descending coronary occlusion apparently does not reverse cardiac dysfunction in the first 2 hours of treatment.

Echocardiographic assessment of “compensatory hyperactivity” of opposing cardiac wall motion in acute experimental myocardial ischemia

Echocardiographic assessment of “compensatory hyperactivity” of opposing cardiac wall motion in acute experimental myocardial ischemia

Correlation between echocardiographically demonstrated segmental dyskinesis and regional myocardial perfusion.

In order to evaluate the relationship between regional myocardial perfusion and segmental dyskinesis, 22 open chest dogs were studied using ultrasound to register cardiac wall motion and radioactive labeled microspheres to determine myocardial perfusion. In six dogs, motion and perfusion were correlated at two levels of partial circumflex coronary artery occlusion followed by complete occlusion. A good correlation between declining myocardial perfusion of all the ischemic segments and development of aneurysmal bulging (during isometric contraction) was seen: r = minus 0.80. A similar correlation between myocardial perfusion and endocardial wall velocity (during systolic ejection) was observed: r = 0.92. In nine dogs, the effect of 45 minutes of complete coronary occlusion followed by 30 minutes of reperfusion was evaluated with respect to perfusion and motion. After coronary reperfusion myocardial perfusion of the ischemic area returned to control levels (from 32.6 +/- 3.5 to 130.3 +/- 13.3 ml/100 g/min), but aneurysmal bulging during isometric contraction persisted. Endocardial wall velocity during systolic ejection showed a variable response to reperfusion, achieving values ranging from 32% to 162% of the preocclusion levels. In seven dogs the ultrasound beam was reflected off nonischemic myocardium adjacent to areas of ischemia resulting from coronary occlusion. Despite preservation of normal myocardial perfusion in these nonischemic areas wall motion abnormalities were evident: endocardial wall velocity declined from 25.8 +/- 5.8 to 14.0 +/- 4.9 mm/sec (P less than 0.01), and aneurysmal bulging in three animals. These changes may be due to transient undetected ischemia in the segments struck by the ultrasound beam, or to passive alteration of the motion of the normally perfused areas by the severe dyskinesis of the adjacent ischemic myocardium.

Myocardial Wall Motion Evaluation Using Amplitude Frequency Spectral Analysis

Frequency spectral analysis of cardiac wall motion as calculated from the recorded video kymogram are demonstrated. Characteristic harmonics following the fundamental frequency of the cardiac rate have been demonstrated to have an alternating sequential energy distribution as measured from the free margin of the left ventricle of humans. The characteristic patterns occur in approximately 80% of the 50 patients evaluated. The correlation of these harmonics with physiologic events is not yet complete. Amplitude frequency spectral analysis offers an objective method for analysis of cardiac kymography not otherwise possible.