Use of the systolic time intervals in clinical pharmacology.
Explore the source record for details and available documents.
Electrocardiography↗
Biomedical subjects
D G Gibson
Publications and source records attributed to D G Gibson.
Regional left ventricular wall movement in hypertrophic cardiomyopathy.
Left ventriculograms of 20 patients with hypertrophic cardiomyopathy were digitised frame by frame and analysed using a contour display. Abnormalities of regional wall movement were present in 17, and included an abnormal sequence of inward movement during systole (13), regional delay in the onset of inward movement (10), and an abnormal dispersion of peak velocities (5). Diastolic wall movement was disturbed in 13, because of abnormal peak velocities in 7 and regional asynchrony in 6. Abnormal wall movement during the two isovolumic periods was rare in hypertrophic cardiomyopathy, unlike ischaemic heart disease. These disturbances may reflect underlying structural abnormalities.
Cardiomyopathy, Hypertrophic↗
Analysis of regional left ventricular wall movement by phased array echocardiography.
Images from standard two-dimensional echocardiographs do not lend themselves to the study of regional left ventricular wall movement because of poor definition of endocardium. An alternative method, based on a wide-angle phased array sector scanner has, therefore, been devised. Once the appropriate region of the heart has been identified, the scan rate is increased, and an array of 41 M-mode scans is produced, resulting in improved frequency response and endocardial definition. Each scan is digitised separately, and since their spatial orientation is known, the left ventricular image can be reconstituted by computer, and isometric or contour displays produced. Preliminary results, based on 40 patients, are presented showing examples of left ventricular wall movement. Regional abnormalities of amplitude or timing can be displayed with results similar to those of angiography, while disturbances of septal motion or wall thickness can be observed in greater detail than with other methods.
Computers↗
Study of left ventricular wall thickness and dimension changes using echocardiography.
Explore the source record for details and available documents.
Adolescent↗
Detection of abnormal left ventricular wall movement during isovolumic contraction and early relaxation. Comparison of echo- and angiocardiography.
Abnormal left ventricular wall movement during isovolumic contraction and early relaxation was assessed from simultaneous apex and echocardiograms in 50 patients with ischaemic heart disease, and compared with estimates from the corresponding digitised left ventriculograms. During isovolumic contraction, a normal angiogram was accompanied by normal apex-dimension relations in 13 out of 14 cases. In 19 cases, there was angiographic evidence of discrete outward wall movement during isovolumic contraction which was associated with abnormal apex-dimension relations in 15. During isovolumic relaxation, of 14 cases who were normal angiographically, apex-dimension relations were normal also in 11, which in 36 patients with abnormal wall movement on angiogram, apex-dimension relations were abnormal in 30. Correlation was less good between echocardiographic and angiographic estimates of left ventricular minor dimension (r = 0.75), and was absent between those of peak rates of dimension change during systole and diastole. Asynchronous onset of inward wall movement and the distribution of regional abnormalities of overall wall movement amplitude were unrelated to apex-dimension relations. The apex-dimension relation is thus a sensitive and specific means of detecting abnormalities of left ventricular wall movement during isovolumic contraction and early relaxation, unaffected by other manifestation
Angiocardiography↗
Left ventricular relaxation and filling in hypertrophic cardiomyopathy. An echocardiographic study.
Echocardiograms showing left ventricular cavity and mitral valve cusps simultaneously were recorded in 36 patients, apex cardiograms being obtained in 26 of them. These were digitised and continuous plots made of left ventricular dimension, its rate of change, and anterior mitral leaflet velocity, and were compared with those in 20 normal subjects. Peak mitral diastolic closure rate was reduced to 120 +/- 80 mm/s, compared with normal (250 +/- 60 mm/s). Peak rate of increase of dimension was normal (13.4 cm/s), though the pattern of filling was disturbed, with the duration of rapid filling prolonged in 5, and shortened in 15, suggesting restriction. Mitral valve opening, normally synchronous with minimum dimension, was delayed by a mean of 76 ms, and during this period there was an abnormal increase in dimension. Dimension also increased by 50 +/- 25 per cent of the total diastolic excursion before the 'O' point of the apex cardiogram compared with 21 +/- 7 per cent in normals, and the timing of peak rate of increase of dimension was delayed by 50 +/- 20 ms instead of being synchronous with the 'O' point as normal. None of these findings correlated with the reduction in peak mitral diastolic closure rate. Noninvasive methods thus show that relaxation may be abnormal in hypertrophic cardiomyopathy. Delay in mitral valve opening and disturbances in the rate, duration, and co-ordination of wall movement during filling suggest the presence of segmental abnormalities of left ventricular function.
Adolescent↗
Abnormal left ventricular wall movement during early systole in patients with angina pectoris.
Explore the source record for details and available documents.
Angina Pectoris↗
Echocardiographic assessment of left ventricular filling and septal and posterior wall dynamics in idiopathic hypertrophic subaortic stenosis.
In order to study left ventricular function in idiopathic hypertrophic subaortic stenosis (IHSS), left ventricular echograms were analyzed by computer and compared with results in normal subjects. Systolic function was consistently normal or above normal even in the presence of severe diastolic abnormalities. Wide variation in diastolic function in IHSS allowed separation of patients into three groups on the basis of the left ventricular peak filling rate. Because of the severe septal hypertrophy and hypokinesia, peak left ventricular filling rate is predominantly determined by the rate of free wall thinning. Patients in group 1 had rapid left ventricular filling rates, those in group 2 had normal filling rates, and those in group 3 had slow filling rates. With reduction in left ventricular peak filling rate caused by impaired free wall thinning, there was progressive increase in 1) duration of the rapid filling phase, 2) delay of mitral valve opening, 3) asynchrony between septum and posterior wall, 4) incidence of angina, and 5) incidence of atrial fibrillation.
Adolescent↗
Diastolic changes in left ventricular wall thickness studied by echocardiography.
In order to study factors influencing posterior wall thickness during diastole, echocardiograms showing the septum, mitral valve and posterior wall endocardium and epicardium in 15 normal subjects and 49 patients with heart disease were digitized. Maximum wall thickness, minimum cavity dimension and the onset of mitral valve opening are normally synchronous, and an early period of rapid wall thinning, at a peak rate of 10.7 +/- 1.7 cm/sec corresponds closely to rapid filling. In patients with ischaemic heart disease the peak rate and duration of rapid thinning were normal, but thinning preceded mitral valve opening (mean 50 msec). In 11 of 17 patients with hypertrophic cardiomyopathy the peak rate of thinning was reduced and in 2 it was increased. There was a close correlation between the peak thinning rate in this group and the peak rate of increase in dimension. In mitral stenosis peak thinning rate was frequently reduced but in some patients was normal, with the reduced rate of increase in cavity dimension maintained by reversal of septal movement. We conclude that rapid thinning is an intrinsic property of the ventricular wall which is normally associated with rapid filling, but which may be dissociated from filling by asynchronous relaxation or inflow obstruction, or may be modified by myocardial disease.
Cardiomyopathy, Hypertrophic↗
Regional abnormalities of left ventricular wall movement during isovolumic relaxation in patients with ischemic heart disease.
In order to study events during isovolumic relaxation, left ventricular angiograms of 120 patients with ischemic heart disease were digitized frame by frame, and compared with those of 15 normal subjects. In patients with ischemic heart disease, abnormal inward movement of endocardium occurred in areas supplied by narrowed coronary arteries. When these involved the free wall, they were due to abnormal wall thickening rather than to inward movement of epicardium. Since the volume of the ventricle was constant, they were accompanied by compensatory outward movement of endocardium elsewhere, due to premature thinning. Identical abnormalities were demonstrated in 80 patients by M-mode echocardiography, and in individual patients, agreement with angiography was good. These abnormalities were aggravated by TNT administration, and were unaffected by isometric stress. In approximately half, they were associated with abnormalities of isovolumic contraction. They appear to represent the behavior of regions of the left ventricle with partial loss of function due to previous ischemic injury.
Cineangiography↗
Measurement of postoperative pericardial pressure in man.
Pericardial pressure was measured in 18 patients undergoing cardiopulmonary bypass for up to 10 days using a solid state transducer. Mean and phasic pericardial pressure wave forms were similar to those reported in animals. A wide range of mean pressure from 0 to 30 mmHg was recorded, and values of up to 20 mmHg were observed in patients whose postoperative clinical course was uncomplicated. Fluctuations in pericardial pressure during spontaneous and artificial respiration were small, suggesting that concomitant left ventricular diastolic pressure changes were mainly the result of alterations in diastolic filling. Relative ventricular and pericardial distensibilities were estimated from the ratio of the slopes of diastolic pressure with time, which showed that up to 25 per cent of left ventricular diastolic pressure was supported by the pericardium and 75 per cent by the myocardium. Measurement of pericardial pressure had clinical value in 2 patients in confirming and excluding the presence of pericardial tamponade.
Adolescent↗
Echocardiographic assessment of left ventricular filling after mitral valve surgery.
In order to investigate the functional effects of mitral valve surgery, echocardiograms showing left ventricular dimension were recorded and digitised in 14 normal subjects and 129 patients after mitral valve surgery. Measurements were made of peak rate of increase of dimension (dD/dt) and duration of rapid filling, studies on left ventriculograms in 36 patients having shown close correlation between these values and changes in cavity volume. In 14 patients with mitral stenosis, peak dD/dt was reduced to 7-2 +/ 1-5 cm/s, and filling period prolonged to 330 +/- 65 ms, compared with normal (16-0 +/- 3-2 cm/s, and 160 +/- 50 ms, respectively), and after mitral valvotomy, these values improved significantly (10-4 +/- 2-7 cm/s and 245 +/- 55 ms). Characteristic abnormalities were found in 67 patients with mitral prostheses. Values for the Björk-Shiley (10-5 +/- 4-2 cm/s and 180 +/- 80 ms) and Hancock (10-3 +/- 3-7 cm/s, 245 +/- 80 ms) values were similar, and both superior to the Starr-Edwards (7-4 +/- 3-0 cm/s, 295 +/- 105 ms). Results after mitral valve repair in 30 cases were not significantly different from normal (14-4 +/- 5-0 cm/s, 170 +/- 50 ms). Values outside the 95 per cent confidence limits for the valve in question allowed diagnosis of value malfunction in 18 cases. The method is value in comparing different operative procedures and in following up patients after mitral valve surgery.
Adolescent↗
Changes in left ventricular free wall thickness in patients with ischaemic heart disease.
Explore the source record for details and available documents.
Angiocardiography↗
Relation between apex cardiogram and changes in left ventricular pressure and dimension.
The relation between the apex cardiogram and changes in left ventricular pressure measured by micromanometer, and dimension measured by echocardiography, was studied in 12 normal subjects and 64 patients with heart disease. In 12 patients, the apex cardiogram was delayed with respect to simultaneous left ventricular pressure by 17 +/- 18 ms during the upstroke and 28 +/- 16 ms during the downstroke. In the normal subjects, changes in left ventricular dimension during the upstroke and downstroke of the apex cardiogram were small, amounting to 6 +/- 5 and 21 +/- 7 per cent total excursion, respectively. In 10 patients with mitral regurgitation, there was significant inward wall movement during the upstroke and in 10 patients with aortic regurgitation, significant outward movement during the downstroke, both reflecting valvular regurgitation. In 20 patients with ischaemic heart disease and segmental abnormalities on left ventricular angiography, apex cardiogram-echo dimension relations were abnormal in all, because of inward or outward wall movement during the upstroke, increased outward movement before the 'O' point, or abnormal inward movement during the downstroke. These disturbances were displayed by constructing apex cardiogram-echo dimension loops, which appear to be a sensitive means of detecting incoordinate left ventricular contraction, analogous to those between pressure and dimension.
Adolescent↗
Echocardiographic diagnosis of primitive ventricle with two atrioventricular valves.
Anatomical studies have shown that the pathognomonic feature of primitive ventricle is absence of that portion of the interventricular septum which interposes between the atrioventricular valves. The relation of this posterior septum to the atrioventricular valves is such that echocardiography should be a particularly suitable technique for showing its presence or absence. When a posterior septum is present, it is seen on an echocardiogram as a double echo between the two atrioventricular valves. It presence limits posterior movement of the septal cusp of the anterior atrioventricular valve. Absence of the posterior septum should, therefore, be seen echocardiographically as more than mere absence of the double septal echo. It should be possible to show unusual posterior excursion of the "septal" cusp of the anterior atrioventricular valve and apposition of the "septal" cusps of the atrioventricular valves during diastole. In most instances it should also be possible to demonstrate that the posterior great artery is in continuity with both atrioventricular valves. We have shown these echocardiographic features in 26 patients. The diagnosis of primitive ventricle has been confirmed at necropsy or at operation in 4 patients. In the other 22 patients in angiographic data are compatible with a diagnosis of primitive ventricle. Demonstration of these positive features at echocardiography is, therefore, of considerable value in the initial diagnosis of primitive ventricle and in particular its differentiation from other congenital malformations.
Echocardiography↗
Left ventricular filling in hypertrophic cardiomyopathy. An angiographic study.
In order to study left ventricular filling in hypertrophic cardiomyopathy, left ventricular cineangiograms of 20 patients were digitised frame by frame and compared with those of 10 normal subjects. Peak left ventricular filling rate was 770+/-260 ml s-1 (mean+/-1 standard deviation), not significantly different from normal. Mitral valve opening was delayed, occurring 140+/-40 ms after time of minimum cavity area, compared with 93+/-14 msec in normals (P less than 0-01), indicating abnormal relaxation. Peak left ventricular filling rate was correlated inversely with this delay (r = 0-69, P less than 0-01), which was greater in patients with angina (155+/-27 ms) than in those without (85+/-23 ms) (P less than 0-01). The rapid filling period was also abnormally prolonged in 8 patients. End-diastolic transverse dimension was normal (5-3+/-0-7 cm) but end-systolic dimension was reduced (2-4+/-0-4 cm) (P less than 0-01) because of abnormal cavity shape. Peak rate of change of dimension during filling (18-7+/-5-3 cm s-1) was greater than normal (11-3+/-3-9 cm s-1) (P less than 0-01), and correlated with peak filling rate (r = 0-82, P less than 0-001). Thus, peak filling rate is normal in hypertrophic cardiomyopathy, but the filling pattern may be abnormal, apparently because of impaired relaxation and abnormal cavity shape rather than mechanical obstruction to inflow.
Adult↗
Instantaneous mitral valve leaflet velocity and its relation to left ventricular wall movement in normal subjects.
Echocardiograms showing mitral valve leaflets, interventricular septum, and posterior wall of the left ventricle simultaneously were recorded at a paper speed of 100 mm/s in 20 normal subjects. These records were manually digitized and a computer was used to derive mitral valve velocity, left ventricular dimension, and its rate of change continuously throughout a single cardiac cycle. The pattern of instantaneous mitral valve velocity with respect to time was similar in all subjects studied, showing a peak opening rate of 400 +/- 60 mm/s (mean +/- 1 SD), and continuously changing velocity throughout the period of mid-diastolic closure. The peak diastolic closure rate was 250 +/- 60 mm/s and thus appreciably higher than average velocities obtained by manually measuring the slope. A close time relation existed between mitral valve and left ventricular wall movement in early diastole. Forward movement of the anterior leaflet began 1 +/- 6 ms after the onset of outward wall movement, and peak velocity was reached 2 +/- 7 ms after the maximum rate of change of dimension. Later, a discontinuity in wall movement at the end of rapid filling preceded a corresponding discontinuity in the mitral valve velocity tracing by 5 +/- 10 ms. The technique, therefore, allows continuous measurement of mitral valve velocity, and demonstrates its close relation to left ventricular wall movement during diastole.
Adolescent↗
Assessment of left ventricular systolic function in man from simultaneous echocardiographic and pressure measurements.
Simultaneous measurements of left ventricular dimension and wall thickness by echocardiography, and of pressure by micromanometer, were made at cardiac catheterization in 30 patients with heart disease, in order to study mechanisms of impairment of left ventricular systolic function. Echocardiograms and pressure traces were digitized so that continuous measurements of left ventricular wall thickness and dimensions with their rates of change could be obtained. Ejection fraction was estimated from digitized cineangiograms. In all patients, except those with severe mitral regurgitation, there was close correlation (r=0.92) between peak left ventricular dP/dt and peak rate of reduction of dimension. Myocardial power values, calculated as the product of circumferential shortening rates and wall stress were plotted throughout the cardiac cycle, and peak values in patients with normal left ventricular function were in the range 30 to 60 mW cm-3 myocardium. Pressure-dimension loops were constructed, which reflected the relation between the function of a localized region of cavity studied by echocardiography and that of the ventricle as a whole in the pressure wave form. Incoordinate contraction was associated with distortion of the loop and a reduction in its area to less than 75% that of the maximum for the cycle in question (cycle efficiency). In patients with left ventricular disease, ejection fraction, peak power, and cycle efficiency were all reduced, either singly or in combination. There was no consistent pattern, however, suggesting that clinical left ventricular disease may be the resultant of a number of different types of disturbance. These include structural abnormalities, reduction in peak rates of myocardial shortening or power development, and incoordinate contraction. The present investigation suggests ways in which these may be separated and studied in individual patients.
Adolescent↗