Biomedical subjects

D G Gibson

Publications and source records attributed to D G Gibson.

At least 109 records · Page 6Linked to original sources

PubMed1991

Diastolic disease in left ventricular hypertrophy: comparison of M mode and Doppler echocardiography for the assessment of rapid ventricular filling.

OBJECTIVE: To investigate possible discrepancies between M mode and Doppler echocardiography in assessing early diastolic filling. DESIGN: Forty seven patients with left ventricular hypertrophy due to aortic stenosis and 26 healthy controls with a similar age range were studied by M mode, Doppler, apexcardiography, and phonocardiography. The patients also underwent cardiac catheterisation. M mode echograms were digitised by a computer. Early diastolic filling in both groups as assessed by the two techniques was compared. SETTING: A tertiary cardiac referral centre with facilities for non-invasive and invasive investigations. SUBJECTS: Patients referred for assessment of aortic stenosis who had left ventricular hypertrophy. MAIN OUTCOME MEASURES: Filling velocities on Doppler and rates of wall thinning and dimension increase on M mode. RESULTS: Digitised M mode indices of diastolic filling (peak wall thinning rate 6.4 (3.0) v 10.0 (3.0) cm/s and peak rate of dimension increase 9.3 (3.3) v 16 (4.5) cm/s) in the patients and controls were consistently different. In contrast, the Doppler A/E ratio and peak E wave velocity were not; they varied widely among patients with left ventricular hypertrophy. In part, this variability was because the Doppler A/E ratio, but not the digitised M mode indices, was very sensitive to the abnormalities of isovolumic relaxation frequently present in left ventricular hypertrophy. The Doppler A/E ratio varied similarly with age in both normal and hypertrophied hearts; in the patients with ventricular hypertrophy the peak rate of dimension increase depended on age only, whereas the thinning rate was independent of age in both the patients and controls. Neither the A/E ratio nor the M mode indices could be related to the left ventricular end diastolic pressure or the peak aortic pressure difference. CONCLUSIONS: When Doppler and M mode techniques are used to assess rapid filling in patients with left ventricular hypertrophy the M mode indices are more consistently abnormal. The two methods measure different aspects of left ventricular diastolic function and should be regarded as complementary rather than interchangeable.

Adolescent↗

PubMed1991

Analysis of left ventricular wall movement before and after reimplantation of anomalous left coronary artery in infancy.

Five infants who underwent direct reimplantation or redirection of an anomalous left coronary artery from the pulmonary artery to the aorta were studied. There were no deaths from the procedure. Anastomoses were patent at a mean follow up of 33 months. Left ventricular angiograms before and after operation were digitised frame by frame. Analysis of wall motion showed considerable generalised hypokinesia with no change in cavity shape before operation. After reimplantation there was a significant improvement of global ventricular function as assessed by ejection fraction and end diastolic shape index. There was also a tendency for the shape index change to increase; this was compatible with better global systolic function. Three of the four patients who were restudied showed normal isometric and contour wall motion plots. One child, the oldest at the time of operation, still showed asynchronous onset of contraction and isovolumic relaxation. The procedure offers a low risk of mortality and a high rate of patency of the anastomosis. Improvement of ventricular function can be remarkable and its extent cannot be assessed simply by ejection fraction measurements.

Anastomosis, Surgical↗

PubMed1991

Jugular venous 'a' wave in dilated cardiomyopathy: sign of abbreviated right ventricular filling time.

OBJECTIVE: To study the mechanisms underlying the high venous pressure often seen in patients with dilated cardiomyopathy. DESIGN: Retrospective and prospective examination of the pattern of flow in the superior vena cava, cardiac echo-Doppler studies, and recordings of the jugular venous pulse. SETTING: A tertiary referral cardiac centre. PATIENTS PARTICIPANTS: 23 patients with dilated cardiomyopathy, all with functional mitral and tricuspid regurgitation. RESULTS: Two patterns of venous pulse were seen: a dominant 'a' wave and 'x' descent, with systolic flow in the superior vena cava (group 1, n = 11), and a dominant 'v' wave with 'y' descent and diastolic flow in the superior vena cava (group 2, n = 12). A comparison of group 1 and group 2 showed: age (mean (SD] 58 (12) v 61 (6) years, left ventricular end diastolic dimension 7.0 (0.7) cm in both groups, right ventricular short axis 3.3 (0.6) v 3.6 (0.5) cm and long axis 7.3 (0.5) v 7.1 (0.7) cm, and duration of tricuspid regurgitation 350 (65) v 370 (50) ms. The RR interval (550 (100) v 680 (80) ms) and right ventricular filling time (150 (30) v 290 (50) ms) were significantly shorter in group 1. In all patients in group 2 right ventricular filling time was more than 200 ms with separate E and A waves on the tricuspid Doppler echocardiogram, while in all group 1 patients it was less than 200 ms with a single summation peak. In nine patients in group 1, the right ventricular filling time was limited by prolonged tricuspid regurgitation and in the remaining two by prolonged isovolumic relaxation time (215 (80) ms), so that it was consistently significantly less than that of the left ventricle. CONCLUSION: In patients with dilated cardiomyopathy, right ventricular filling time may be so short that it limits stroke volume. Such patients can be recognised by a dominant 'a' wave on the jugular venous pulse. Patients in whom the right ventricular filling time was longer showed a dominant 'v' wave. Both groups can present as "congestive heart failure".

Adult↗

PubMed1991

Isovolumic relaxation sound: a new class of added heart sound?

An early diastolic sound in a patient with apical left ventricular disease is reported. Pulsed Doppler echocardiography showed blood flow within the left ventricular cavity during the isovolumic relaxation period whose peak flow velocity was synchronous with the onset of this diastolic sound. Because it occurred before filling started it could not have been either a third or fourth heart sound. It must thus represent a distinct and apparently unrecognised class of diastolic sound.

Aged↗

PubMed1991

Cardiac function after surgery for subaortic stenosis: non-invasive assessment of left ventricular performance.

OBJECTIVE: To examine left ventricular function after surgical resection of subaortic stenosis during childhood. DESIGN: Left ventricular performance was measured non-invasively in all patients who responded to an invitation for formal assessment. SETTING: Outpatient study, tertiary referral centre. PATIENTS: Twenty three (12 male and 11 female) patients (age range 3 to 31 years) of 43 consecutive patients with fixed subaortic stenosis undergoing surgical resection between 1975 and 1989 reattended for formal assessment 16 months to 15 years (median 4 years 4 months) after operation. MAIN OUTCOME MEASURES: Left ventricular dimension, left ventricular wall thickness, left ventricular Doppler inflow velocities, and left ventricular diastolic pressure (measured from apexcardiograms). Results were compared with those in controls individually matched for age and sex. RESULTS: All patients were symptom free. Left ventricular cavity dimensions were normal, as was the mean fractional shortening. Posterior wall thickness tended to be greater in the patients and there was a significant increase in septal thickness. Normalised peak rate of posterior wall thinning was significantly lower in the patients and the isovolumic relaxation time was significantly shorter. Doppler inflow velocity measurements showed that early diastolic mitral flow acceleration time was normal but deceleration time was significantly shorter in the patients. The ratio of mitral flow in early diastole (E) to E plus mitral flow in late diastole (A) was significantly higher in the patients and in two patients there was complete absence of A wave flow despite large A waves on the apexcardiogram. CONCLUSIONS: Systolic function was well preserved in patients after operation for subaortic stenosis. A restrictive pattern of left ventricular filling was common, however, and presumably reflected a response to the chronic pressure load and to surgery in the paediatric heart.

Adolescent↗

PubMed1991

Relation between cyclic variation in echo amplitude and segmental contraction in normal and abnormal hearts.

OBJECTIVE: To study the relation between cardiac systolic activity and cardiac cycle dependent variation in the ultrasound signal arising from within the myocardium. DESIGN: Regional echo amplitude was used as a measure of the myocardial ultrasound signal. Relative echo amplitude values were assigned by standardising echo gain using the posterior parietal pericardium as an in-vivo calibration. M mode measurements of the left ventricle were used to assess cardiac systolic activity. Subjects were studied prospectively. Analysis of echo amplitude was performed by investigators who were blinded to the results of the M mode analysis. The influence of impaired left ventricular performance and abnormal wall motion were assessed. PATIENTS: 11 cardiomyopathy patients with impaired ventricular function, eight patients with severe pulmonary hypertension and reversed septal motion, and 19 healthy controls. SETTING: All subject studies were performed at Harefield Hospital. Echo amplitude analysis was performed at the Royal Brompton Hospital. MAIN OUTCOME MEASURES: Cyclic variation in echo amplitude was determined as the change in echo amplitude from end diastole to end systole. Additionally, an index of cyclic variation defined as the ratio of the cyclic change in echo amplitude to end diastolic echo amplitude was measured. Both cyclic variation and the cyclic variation index were analysed to see whether they correlated with left ventricular dimensions, fractional shortening, and systolic wall thickening. RESULTS: Stepwise regression analysis showed systolic wall thickening to be the most significant independent variable that correlated with the cyclic variation index for both the septum and posterior wall (r = 0.68, p = 0.0001, septum; r = 0.69, p = 0.0001, posterior wall). The slopes and intercepts for both regression equations were similar (y = 0.005x + 0.006, septum; y = 0.006x + 0, posterior wall). Subgroup analysis showed that the healthy controls, patients with cardiomyopathy, and patients with pulmonary hypertension had similar slopes and intercepts for their individual regression equations. CONCLUSIONS: These data support the hypothesis of a quantitative relation between the extent of cyclic variation of echo amplitude and the degree of segmental myocardial shortening, as measured by systolic wall thickening, which is not significantly influenced by location within the myocardium, left ventricular performance, or wall motion. They provide further evidence of the usefulness of quantitative analysis of myocardial echo amplitude in the study of regional myocardial function in both normal and injured myocardium.

Adult↗

PubMed1991

Effect of left bundle branch block on diastolic function in dilated cardiomyopathy.

OBJECTIVE: To assess the diastolic effect of left bundle branch block in patients with dilated cardiomyopathy. DESIGN: Retrospective study of M mode and Doppler echocardiograms along with electrocardiogram and phonocardiogram. SETTING: Tertiary referral cardiac centre. PATIENT PARTICIPANTS: Fifty two patients with dilated cardiomyopathy, all with functional mitral regurgitation. Twelve with left bundle branch block (group 1) were compared with 40 without (group 2). RESULTS: Mean (SD) age 60 (15) v 55 (18) years, left ventricular end diastolic dimension 72 (9) v 70 (7) mm, and heart rate 88 (15) v 84 (15) beats/min were similar in both groups. In patients with left bundle branch block the electromechanical delay, 50 (20) v 70 (20) ms, was shorter (p less than 0.05) whereas the preejection contraction time, measured from the onset of mitral regurgitation to that of aortic ejection, 130 (40) v 70 (20) ms (p less than 0.01), and left ventricular relaxation time, A2 to the end of mitral regurgitation, 130 (30) v 80 (30) ms (p less than 0.01), were both prolonged. Ejection time itself was similar, 230 (40) v 235 (40) ms. Thus the overall duration of mitral regurgitation was increased (495 (90) v 390 (60) ms (p less than 0.01], which made filling time shorter (190 (45) v 325 (90) ms (p less than 0.01]. In patients with left bundle branch block, unlike those without, contraction and relaxation times both shortened as RR interval fell; this made the duration of mitral regurgitation more sensitive to heart rate. Filling time was less than 200 ms in eight out of 12 patients with left bundle branch block and four out of 40 patients without (p less than 0.001). CONCLUSION: Left bundle branch block prolongs rather than delays mitral regurgitation by increasing pre-ejection and relaxation times. This directly impairs diastolic function by shortening the time available for the left ventricule to fill to an extent likely to limit stroke volume.

Bundle-Branch Block↗

PubMed1990

Enhanced deposition of predominantly type I collagen in myocardial disease.

The myocardium consists of a muscle fibre array surrounded and interspersed by a network of connective tissue, principally collagen, which maintains the functional integrity of the heart. Changes in collagen composition may therefore contribute to altered ventricular function. Collagen composition was examined in cardiac tissue from 15 patients undergoing orthotopic cardiac transplantation. Of these, 10 had severely impaired left ventricular function due to coronary artery disease. The remaining five had dilated cardiomyopathy. Normal heart tissue was taken at autopsy from 25 patients who died of causes unrelated to cardiovascular disease. Left ventricular collagen concentration, estimated from hydroxyproline levels, increased from 48.6 +/- 4.1 mg/g dry weight of tissue in the control group to 95.3 +/- 9.7 mg/g (P less than 0.01) in patients with dilated cardiomyopathy and to 63.5 +/- 9.8 mg/g in the coronary artery disease group. This increase was attributable to an increase in absolute concentrations of both type I and III collagen, determined by separation of cyanogen bromide peptides by sodium dodecyl sulphate polyacrylamide gel electrophoresis. However, there was a significant decrease in the proportion of type III collagen (compared with type I plus III) from 41.8 +/- 1.1% in controls, to 34.6 +/- 1.5% (P less than 0.01) in the coronary artery disease group and 35.8 +/- 2.8% (P less than 0.05) in the dilated cardiomyopathy group. These results suggest that excessive collagen production, with a preponderance of type I, occurs in these forms of myocardial disease, indicative of a remodelling of the collagen matrix, which, by increasing passive myocardial stiffness may contribute to impaired heart function seen in these groups of patients.

Adult↗

PubMed1990

Relation of filling pattern to diastolic function in severe left ventricular disease.

M mode and Doppler echocardiograms, apex cardiograms, and phonocardiograms were recorded in 50 patients with severe ventricular disease of varying aetiology to examine how left ventricular filling is disturbed by cavity dilatation. The size of the left ventricular cavity was increased in all with a mean (SD) transverse diameter of 7.2 (0.8) cm at end diastole and 6.3 (0.8) cm at end systole. All were in sinus rhythm and 35 had functional mitral regurgitation. In nine patients, in whom filling period was less than 170 ms, transmitral flow showed only a single peak, representing summation. In the remainder there was a strikingly bimodal distribution of filling pattern. In 12 the ventricle filled dominantly with atrial systole (A fillers). Isovolumic relaxation was long (75 (35) ms) and wall motion incoordinate; mitral regurgitation was present in only one. In most (29) the left ventricle filled predominantly during early diastole (E fillers). Mitral regurgitation, which was present in 26, was much more common than in the A fillers, while the isovolumic relaxation time (10 (24) ms) was much shorter and the normal phase relations between flow velocity and wall motion were lost. In 24 E fillers no atrial flow was detected. In four there was no evidence of any mechanical activity, suggesting "atrial failure". In 20, either the apex cardiogram or the mitral echogram showed an A wave, implying that atrial contraction had occurred but had failed to cause transmitral flow, showing that ventricular filling was fundamentally disturbed in late diastole. A series of discrete abnormalities of filling, beyond those shown by Doppler alone, could thus be detected in this apparently homogeneous patient group by a combination of non-invasive methods. The presence and nature of these abnormalities may shed light on underlying physiological disturbances.

Blood Flow Velocity↗

PubMed1990

Functional importance of the long axis dynamics of the human left ventricle.

The role of longitudinally and circumferentially oriented fibres in left ventricular wall motion was examined by digitising echocardiograms of the mitral ring (whose motion reflects long axis change) and of the standard minor axis in 36 healthy individuals, 36 patients with coronary artery disease, 16 with left ventricular hypertrophy, 44 with mitral valve disease (24 of whom had undergone mitral valve replacement). In the controls long axis shortening significantly preceded minor axis shortening (mean (1 SD) difference 25 (40) ms) so that the minor axis increased more during isovolumic contraction (0.25 v 0.09 cm), indicating that the left ventricle became more spherical. Changes in the long and short axes were synchronous at end ejection and in early diastole in the controls. Epicardial excursion preceded endocardial excursion by 50 (20) ms at its peak. These time relations were consistently disturbed in all patient groups, irrespective of the extent of fractional shortening of the minor axis. The onset of long axis shortening was delayed, and this was often associated with premature shortening of the minor axis, the normal spherical shape change during isovolumic contraction was lost, and peak epicardial and endocardial changes became more synchronous. In patients with coronary disease these changes are the expected consequence of ischaemic injury to longitudinally orientated subendocardial fibres. In left ventricular hypertrophy their presence consistently showed systolic dysfunction when orthodox measures were still normal. They were more pronounced after mitral valve replacement when the papillary muscles had been sectioned; long axis shortening was reduced during systole and prolonged into early diastole, while normal shortening of the minor axis was maintained only by abnormal epicardial excursion. Relations between long and short axis motion in healthy individuals are characteristic, and their loss is an early index of systolic ventricular disease. These disturbances precede changes in orthodox measures such as fractional shortening or peak velocity of circumferential fibre shortening.

Cardiomegaly↗

PubMed1990

Discrepancies in the measurement of isovolumic relaxation time: a study comparing M mode and Doppler echocardiography.

Mitral valve cusp separation on M mode echogram, the mitral valve opening artefact, and the onset of forward transmitral flow recorded by Doppler echocardiography have all been taken to mark the end of isovolumic relaxation, while its onset has been taken either as the aortic closure sound (A2) recorded phonocardiographically or the aortic closure artefact determined by Doppler technique. Possible differences in the measurement of the isovolumic relaxation time were studied when these landmarks were used in 44 healthy people, 14 patients with mitral stenosis, 21 patients with left ventricular hypertrophy, and 24 patients with dilated cardiomyopathy by recording M mode echograms of the mitral valve, and pulsed and continuous wave Doppler spectra of transmitral flow, with simultaneous electrocardiograms and phonocardiograms. A2 was effectively synchronous with the aortic artefact. However, when the onset of Doppler flow was regarded as the end of isovolumic relaxation, the interval was significantly longer than when mitral cusp separation on M mode echograms was used: by 25 (10) ms in healthy individuals, by 25 (15) ms in patients with left ventricular hypertrophy, and by 50 (35) ms in patients with dilated cardiomyopathy. In patients with mitral stenosis the interval was only 5 (5) ms longer. The mitral valve opening artefact consistently followed the onset of flow and corresponded much more closely to the E point on the M mode echogram. This shows that it occurred during the rapid filling period and well beyond isovolumic relaxation by any definition. Thus isovolumic relaxation time measured from A2 to the onset of transmitral flow or the mitral valve opening artefact differs from that derived from A2 to mitral valve cusp separation. These intervals cannot be used interchangeably to measure "isovolumic relaxation time".

Adolescent↗

PubMed1990

Relation between intraventricular pressure and volume in diastole.

The pressure-volume curves for 10 patients with various types of heart disease were studied throughout mid to late diastole when both pressure and volume were increasing. The results were used to test a currently held theory that the form of this relation is exponential. It was found that for the patients examined this hypothesis was not valid.

Adult↗

PubMed1990

Presystolic tricuspid valve closure: an alternative mechanism of diastolic sound genesis.

We describe a previously unrecognised cause of an added diastolic heart sound. The patient had first-degree heart block and diastolic tricuspid regurgitation, leading to presystolic closure of the tricuspid valve and the production of a loud diastolic sound. Unlike previously described mechanisms for diastolic sounds, this sound was generated by the sudden acceleration of retrograde AV flow in late diastole.

Aged↗

PubMed1989

Comparison of intravenous nicardipine and nitroglycerin to control systemic hypertension after coronary artery bypass grafting.

The efficacy of intravenous (i.v.) nicardipine hydrochloride (a calcium antagonist) compared with nitroglycerin, the drug generally used for treatment of hypertension after coronary artery bypass grafting, was tested in 20 postoperative patients. The patients were randomly divided in a nonblinded manner into 2 groups. Baseline characteristics were similar in the 2 groups. Patients in both groups received various oral calcium antagonists. In addition, 1 group was treated with i.v. nitroglycerin. Both drugs were infused at a maximal rate of 30 mg/hour, as needed to maintain systolic blood pressure below 110 mm Hg. If blood pressure increased to more than 120 mm Hg, nitroprusside was administered. Intravenous nicardipine was superior to nitroglycerin in control of hypertension after coronary artery bypass grafting. In patients treated with nicardipine, blood pressure was decreased sooner (mean infusion time 7.7 hours vs 11.9 hours for nitroglycerin), mean systolic blood pressure was reduced (94 vs 108 mm Hg for the nitroglycerin group; p less than 0.05), and no patient required nitroprusside treatment (compared with 3 patients who required this treatment in the nitroglycerin group). There were no differences in heart rate, diastolic pressure, cardiac index and urine flow between the 2 treatment groups. No adverse effects were observed in patients treated with nicardipine.

Coronary Artery Bypass↗

PubMed1989

Phase differences between left ventricular wall motion and transmitral flow in man: evidence for involvement of ventricular restoring forces in normal rapid filling.

To assess the possible role of restoring forces underlying left ventricular wall motion during rapid filling, the time relations between left ventricular dimensions and filling velocity were studied by digitised M-mode and Doppler echocardiography in 23 normal children and 43 patients: 11 with mild and 17 with severe mitral regurgitation, and 15 with left ventricular hypertrophy due to aortic stenosis. In normal children, peak mitral flow velocity characteristically lagged peak rate of dimension increase by 50 +/- 15 msec, and peak rate of posterior wall thinning by 35 +/- 15 msec, (P less than 0.01 for both). Towards the apex, and along the long axis of the ventricle, these phase differences between dimension and flow velocity were not apparent. The characteristic time relations between flow velocity and transverse dimension were also present in patients with left ventricular hypertrophy or mild mitral regurgitation, but when mitral regurgitation was severe they were lost and there was no significant difference in timing between peak flow velocity and peak rate of dimension change (-2 +/- 30 msec) or wall thinning (-4 +/- 25 msec). We conclude that phase differences between left ventricular wall motion and mitral inflow velocity are present in the normal ventricles of children. They cannot be explained on the basis of simple shape changes or passive filling of the relaxing ventricle, but strongly suggest the additional presence of ventricular restoring forces. They persist in patients with left ventricular hypertrophy or mild mitral regurgitation, but are lost when the regurgitation is severe, the filling pattern reverting to that predicted for passive distension of the ventricular cavity by a high left atrial pressure.

Adolescent↗

PubMed1989

Coronary arterial surgery in the elderly: its effect in the relief of angina.

Financial and other constraints, such as operative risk, may prevent older patients being considered for coronary arterial bypass grafting. Grafting was performed in 315 elderly patients (244 males, 71 females, age 65-79, mean 69 years) between 1981-1986. All patients had limiting angina, 38% had rest pain, 90% were housebound and 80% had triple-vessel disease. Impairment of left ventricular function was absent in 46%, mild in 20%, moderate in 23% and severe in 10% of patients. Grafts (saphenous vein or internal mammary artery) were inserted into 3 vessels (52%), 4 vessels (42%), 5 vessels (6%), 6 vessels (0.5%). Death during surgery occurred in 1.6% and a further 3.5% of patients died later during the same admission (70% of deaths were among the 33% with preoperative moderate or severe left ventricular impairment). Surgical complications included myocardial infarction (8%), cerebrovascular accident (1%), transient cerebral vascular ischaemia (5%), chest infection (10%) and wound infection (4%). Median stay on the intensive care unit was 1 day and median total hospital stay 12 days. 299 patients therefore survived to leave hospital and follow-up data are available for 217 (72%) of these. 96% were subjectively improved by surgery, 88% being free of angina on no antianginal drugs a median of 72 weeks (range 8-307) and a further 8% not limited by angina on medical therapy a median of 85 weeks (range 9-302) after surgery. We conclude that coronary arterial surgery is an effective treatment for angina in the elderly. This will have consequences for future resource allocation if the elderly are not to be denied effective therapy because of financial rather than clinical restraints.

Aged↗

PubMed1989

Assessment of left ventricular structure and function by cross sectional echocardiography.

Cross sectional echocardiography can be used to give semiquantitative estimates of ventricular volumes and ejection fraction which are very valuable in detecting the severe abnormalities seen clinically. The technique has also been widely used to study regional abnormalities of wall motion. However, with a frame rate of 30 s-1 and lateral resolution of 3-4 mm critical analysis of disturbances of timing is not possible, so the method should be used in conjunction with M-mode and Doppler techniques. In spite of physical limitations, based on the underlying mechanisms of image generation, its advantages of real time application and noninvasive nature, its ability to demonstrate myocardial thickness as well as echo intensity, and its relative cheapness have made cross sectional echocardiography a major tool in documenting abnormalities of left ventricular function occurring in disease.

Cardiac Volume↗

PubMed1989

Left ventricular filling and early diastolic function at rest and during angina in patients with coronary artery disease.

Left ventricular diastolic function was studied in 11 patients with coronary artery disease. Single plane ventriculography (30 degrees right anterior oblique projection) was performed at rest and during an episode of angina immediately after a period of rapid atrial pacing. Left ventricular pressure was recorded simultaneously by a micromanometer tipped catheter. The ventriculograms were digitised frame by frame to derive continuous plots of left ventricular shape, volume, and rate of change of volume. The time constant (tau) of the fall in left ventricular pressure was determined from the exponential portion of pressure decay during isovolumic relaxation. Ventricular pressure-volume loops were constructed to study the left ventricular diastolic pressure-volume relation. The time of minimum left ventricular pressure was used to divide diastole into an early phase and a late phase. Angina was associated with an increase in end systolic volume and a fall in ejection fraction with no significant change in end diastolic volume. Peak left ventricular pressure was unchanged but left ventricular minimum and end diastolic pressures were both increased and the diastolic pressure-volume relation was moved upwards. The time constant of left ventricular pressure fall was prolonged. At rest more than 50% of the stroke volume entered the left ventricle during the period of early diastole. This proportion was significantly reduced during angina and as a consequence a significantly greater proportion of the stroke volume entered the ventricle during late diastole. Despite this, and although the left ventricular diastolic pressure-volume relation was moved upwards with angina, the mean slope of the relation during late diastole--that is, chamber stiffness--was not significantly altered. The upward shift of the left ventricular diastolic pressure-volume relation seen during angina is thus already apparent in early diastole, and its extent does not change during the later phase of diastole, which alone shows the property of passive stiffness. A primary increase in the passive stiffness of the ventricle cannot therefore be the cause of the upward shift of the diastolic pressure-volume relation, and events occurring in early diastole have to be looked to for an explanation. The study findings show that left ventricular function in early diastole is profoundly disturbed during angina pectoris and it is suggested that loss of elastic recoil and dissipation of this restoring force by asynchronous onset of relaxation and abnormal changes in shape are important factors contributing to this disturbance of function.

Adult↗