Jules Fast

Mean transit time for the assessment of myocardial perfusion by videodensitometry.

The intrinsic limitations of coronary arteriography to predict the physiological effects of coronary obstructions are well known. Therefore, more direct assessments of the functional significance of coronary stenoses are becoming increasingly important. Study of contrast passage by electrocardiogram-triggered digital radiography has been proposed as a way of assessing changes in myocardial perfusion. The main problems in this approach are the limited time for motionless image acquisition, the potential alteration of vascular volume between different states, and the changing flow pattern induced by contrast agents. This has led to empiric substitution of mean transit time (Tmn) by other time parameters and to representation of vascular volume by maximal contrast intensity (Dmax). To avoid these problems, intact dogs were studied during almost motionless image acquisition of 20-25 consecutive paced heart beats obtained with synchronous radiographic pulses. In this way, unequivocal and reproducible determination of Tmn was possible. Constant and maximal vascular volume was created by continuous infusion of dipyridamole, and it was proved that coronary flow in this model was not influenced by contrast injections. Flow in the circumflex artery was measured by a ring mounted and calibrated Doppler probe. In each dog, flow in the circumflex artery was varied by a balloon occluder in 12 small steps (range, 0-174 +/- 42 ml/min). Inverse appearance time (1/Tapp), Dmax, Dmax/Tapp, inverse time of maximal intensity (1/Tmax), and 1/Tmn were calculated and the relations of these parameters to measured flow were investigated. Tmn proved to be the most reliable parameter for this purpose (r = 0.97 +/- 0.02; mean +/- SD), followed by Tmax (r = 0.93 +/- 0.04). Dmax failed to represent vascular volume but, in fact, showed a moderate correlation with flow (r = 0.78 +/- 0.22), as did Tapp (r = 0.64 +/- 0.18, 0.75 +/- 0.27, and 0.59 +/- 0.26 for the three definitions of Tapp used in this study). Dmax/Tapp correlated better with flow than either component separately. Our results indicate that the mean transit time calculated by videodensitometry can be used to accurately assess changes in myocardial perfusion strictly according to the original principles of indicator dilution theory.

Abnormal wall movements of the right ventricle and both atria in patients with pericardial effusion as indicators of cardiac tamponade

A retrospective study on 126 patients with pericardial effusion showed cardiac tamponade to be present in 39 patients and absent in 87. We evaluated the distribution of the pericardial effusion as well as the effect of hydrodynamic compression on the different heart chambers. Small to large volumes of pericardial fluid were found in both groups of patients. Abnormal wall movements were only present if pericardial effusion was adjacent. Hydrodynamic compression signs consisted of abnormal wall movements of both atria at end-diastole continuing into systole, and of the right ventricle in early- and mid-diastole. Most of the patients with cardiac tamponade showed an abnormal motion pattern of both right atrium and ventricle (13 patients) or of the right atrial wall alone (12 patients). Abnormal motion of the right ventricle alone was seen in 6 patients, of both atria and right ventricle in 4 and of the left atrium alone in 1 patient. False-negative diagnoses of cardiac tamponade occurred in 3 of the 39 patients and false-positives in 2 of the 87 (sensitivity 92%, specificity 98%). Measurements of the duration of the inversion of both atria increased the specificity of these abnormal wall movements to 100%. Echocardiography can help to identify those patients who are clinically at risk and need pericardial drainage.

Limits of reproducibility of cross-sectional echocardiographic measurement of left ventricular ejection fraction

The total intrinsic variability of echocardiographically determined ejection fraction was evaluated in this study. Cross-sectional left ventricular echocardiograms were made in 14 normal volunteers (9 men, 5 women), ages 31 to 41 years (mean 36 years) with an interval period of about 11 months. We used the parasternal long-axis view, the short-axis view at the papillary muscle level and the four-chamber view from the apex. M-mode recordings were made from the parasternal long-axis view. Simpsons rule and area-length formulas were used to calculate left ventricular volumes and the ejection fraction. From the methods under investigation, the Teichholz technique and the bullet method showed the best reproducibility of the ejection fraction with a coefficient of variation of 4 +/- 3% and 6 +/- 4%, respectively (mean +/- SD). The methods of Baran, and the approach using slices, showed rather large coefficients of variation, 14 +/- 11% and 9 +/- 6%, respectively.

Mean transit time for videodensitometric assessment of myocardial perfusion and the concept of maximal flow ratio: A validation study in the intact dog and a pilot study in man

SummaryOver the last decade it has become more and more obvious that besides anatomical information about the severity of coronary artery stenoses, information about coronary and myocardial blood flow is necessary to understand the functional significance of these obstructions and to evaluate the result of an intervention. Several methods have been proposed for this purpose, each of these having their particular limitations.In this study a new method is shortly described which allows the accurate calculation of relative maximal myocardial perfusion by ECG-triggered digital radiography (videodensitometry), using mean transit time (Tmn) as time parameter; this technique is based on the original physiologic principles of indicator dilution theory. This method was validated in 8 instrumented dogs in which an excellent linear relation was present between 1/Tmn and flow (r=0.96 ± 0.03). Although this method does not allow assessment of resting flow and therefore coronary flow reserve (CFR), it provides a means for the reliable comparison of maximal myocardial flow in different situations and it is independent of most factors affecting coronary flow reserve.The ratio between maximal flow after and before an intervention is called maximal flow ratio (MFR) and this concept was applied in a pilot study in man to evaluate PTCA results in 10 patients undergoing elective angioplasty. MFR was compared with the result of exercise testing 24 hours before and 10 days after the angioplasty. MFR ≥ 1.5 was always accompanied by reversal of exercise test result from positive to negative.We conclude that the accurate calculation of relative maximal perfusion of the myocardium is possible by videodensitometry and suggest that comparison of maximal flow after and before an intervention can be valuable in man for functional evaluation of the result of the intervention.

Determination of cardiac output by single gated pulsed Doppler echocardiography

The aim of the study was to evaluate the use of single gated pulsed Doppler cross-sectional echocardiography for measurement of the cardiac output. Pulsed Doppler echocardiography was used to assess both area and blood velocity at the aortic orifice. Stroke volume estimates were determined by multiplying area by systolic time velocity integral as measured from the parasternal and apical approach, respectively. We investigated a group of 17 healthy individuals and a group of 20 patients with coronary artery disease. In the first group no change was found in aortic area during systole (P less than 0.01). During a follow-up of two weeks no change in aortic area was observed either (P less than 0.01). Intraobserver, interobserver and day-to-day variability of the aortic area, expressed as the coefficient of variation was 3.6 +- 5.2%, 4.6 +- 5.7% and 7.8 +- 3.8% (mean +- 1 SD), respectively. The interobserver variability of the time velocity integrals was 6.0 +- 6.2%. In the second group the cardiac output as measured with the thermodilution method ranged from 3.8 to 8.0 l/min. Comparison of the Doppler and thermodilution technique for measurement of cardiac output showed a correlation coefficient of r = 0.76 (P less than 0.001) and the following regression equation: CO (Doppler) = 1.0 x CO (thermodilution)-700 ml. The Doppler method underestimated cardiac output relative to the thermodilution method.

Limits of reproducibility of mitral pulsed Doppler spectra

The total intrinsic variability of pulsed Doppler spectra of mitral blood flow was evaluated in this study. Doppler examinations were performed in 10 normal volunteers (7 men, 3 women), ages 29 to 57 years (mean 41) with an interval period of 3 months. The recordings were made in the apical 4-chamber view, using a 2.25-MHz transducer. The sample was placed approximately 1 cm proximal (left atrium) and 1 cm distal (left ventricle) from the middle of the anulus of the mitral valve at the onset of diastole. Processing of the raw Doppler spectra was done in a way that avoided subjective manipulation by the investigators. Mitral peak velocities, accelerations and spectral widths were measured in early diastole and late diastole. From the parameters under investigation, maximal velocities showed the best reproducibility with a range of coefficients of variation of 9 to 13%. Peak acceleration in early diastole and spectral widths showed rather large coefficients of variation, ranging from 19 to 30 and 14 to 24%, respectively. Mitral pulsed Doppler spectra in the left atrium were more reproducible than in the left ventricle.

The usefulness of an endomyocardial biopsy in heart disease of unknown etiology

Light-, electron microscopic and enzyme histochemical examinations (phosphorylase, LDH, NADH:TR, SDH and 3-HBDH) were performed on endomyocardial biopsies of 26 patients with heart diseases of unknown etiology. On the basis of the clinical findings the patients were grouped into hypertrophic cardiomyopathy patients), dilated-congestive cardiomyopathy (8 patients), latent cardiomyopathy and small vessel disease (11 patients) and myocarditis (4 patients). Morphologic changes which might characterize the pathogenesis, were found in 7 patients: small vessel disease in 3 patients, nonspecific myocarditis in 1, iron storage disease in 1, adriamycin cardiomyopathy in 1 and cardiomyopathy with inclusions typical of Fabrys disease in 1 patient. In the other patients the morphologic changes were not sufficiently characteristic to be indicative of an etiopathogenesis. Several pathologic alterations did, nonetheless, appear to have a certain prognostic value such as endocardial and interstitial fibrosis, myofibrillolysis, myolysis, mitochondrial degeneration and increased lipid content in the muscle fibers. The frequency of these changes was evaluated partly semiquantitatively, partly by means of the point-counting method and graded with 1-3 points. Three patients with congestive cardiomyopathy scored at least 7 points. Two of them died within 8 weeks, 1 patient with adriamycin cardiomyopathy recovered after discontinuation of the therapy but he died 4 years after the biopsy. Six to 50 months after the biopsy (mean 31.5, median 6.5) the score was less than 7 in the other patients and all these patients were still alive. The histochemical changes manifested as an increase and/or a decrease of the enzymatic activities, involving scattered muscle fibers or their segments. A decrease of the activities of all dehydrogenases examined appeared to be prognostically ominous, correlating with a score of 7 or higher. A decrease of SDH activity in 7 cases, in combination with a decrease of the HBDH activity in 4 of them, was indicative of a disturbance in the Krebs cycle and lipid metabolism in the absence of ischemic damage. The alterations in the phosphorylase activity did not, however, appear to have a prognostic significance. Normal activity of the phosphorylase seemed to be prognostically favorable.

Limits of reproducibility of cross-sectional echocardiographic measurements of left ventricular muscle mass

The total intrinsic variability of echocardiographically determined left ventricular muscle mass was evaluated in this study. Cross-sectional left ventricular echocardiograms were made in 13 normal volunteers (8 men, 5 women), ages 31 to 41 years (mean 36) with an interval period of about eleven months. We used the parasternal long axis view, the short axis view at the papillary muscle level and the four-chamber view from the apex. M-mode recordings were made from the parasternal long-axis view. Left ventricular muscle mass from M-mode recordings was calculated using a simple cube formula and from cross-sectional echo cardiography with an area-length formula. The reproducibility of the left ventricular muscle mass for the methods was respectively 10 +/- 6% and 5 +/- 3% (mean +/- SD). From both methods cross-sectional echo is the method of choice for determining left ventricular muscle mass in man in sequential studies.

Echo diagnosis of ruptured aortic valve leaflet.

artery, and it has been suggested that these patients should be treated by bypass surgery. The mechanism for sudden death is not known. Theories include kinking of the anomalous artery2 and occlusion by a flap-like closure of the ostium as the aorta expands.3 However, sudden death, infarction, and ischemia may occur without regard to the course of the anomalous left coronary artery.4 In the past six years there have been nine cases of an anomalous left coronary artery from the right sinus of Valsalva or right coronary artery out of 7,893 adult cardiac catheterizations performed at Emory University Hospital and Grady Memorial Hospital. The course of the anomalous artery varied posterior to the aorta, anterior to the aorta, and anterior to the pulmonary artery. In only