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Biomedical subjects

A Rickards

Publications and source records attributed to A Rickards.

At least 37 records · Page 2Linked to original sources
PubMed1983

Prolapse of the mitral valve in secundum atrial septal defect: a functional mechanism.

Prolapse of the mitral valve in patients with secundum atrial septal defect has been described angiographically and by two-dimensional echocardiography. It has been suggested that prolapse of the mitral valve in these patients is due to distortion of left ventricular shape and small left ventricular volume. To test this hypothesis 10 patients with unrepaired secundum atrial septal defect and 10 patients who had undergone repair of the defect were studied by two-dimensional echocardiography. The prevalence of mitral valve prolapse was 80% in the unrepaired group and 20% in the repaired group (P less than 0.01). Short axis of the left ventricle revealed septal bulging into the left ventricle, the end-diastolic ratio of minor to major axis being 0.71 in the unrepaired group and 0.93 in the repaired group (P less than 0.001). Systolic and diastolic cross-sectional areas were larger in the repaired group compared with the unrepaired group (P less than 0.05). Prolapse of the mitral valve in patients with secundum atrial septal defect may be related to the distorted left ventricular shape and small left ventricular volume.

Adolescent↗
PubMed1983

Different mechanisms of mitral regurgitation in acute and chronic forms of coronary heart disease.

Contradictory two-dimensional echocardiographic findings have been reported in relation to the role of prolapse of the mitral valve and lack of systolic leaflet coaptation in mitral regurgitation secondary to coronary heart disease. A prospective study of 22 patients with chronic coronary heart disease and mitral regurgitation showed the following: Inferior akinesia was detected in 14 (64%), fibrosis of the postero-medial papillary muscle in 10 (45%), and prolapse of the mitral valve in nine (41%). A combination of the three signs was seen in six patients (27%). Lack of systolic leaflet coaptation was seen in only two patients, both with anterior myocardial infarction. When these results are compared with those reported in the literature, it is apparent that in acute coronary heart disease, lack of leaflet coaptation is frequently visualized (P less than 0.01) and fibrosis of the postero-medial papillary muscle and prolapse of the mitral valve are lacking (P less than 0.01). A unitary explanation of all forms of mitral regurgitation in coronary heart disease is misleading; mechanisms of mitral regurgitation in coronary heart disease depend on the clinical presentation--acute or chronic, the site of infarction, and the presence of cardiac dilatation.

Adult↗
PubMed1982

Left and right ventricular morphology in complex congenital heart disease defined by two dimensional echocardiography.

The ability of two dimensional echocardiography to define right and left ventricular morphology in congenital heart disease was examined in 19 patients with discordant ventricular connections and abnormal relations, but with two ventricles and two unambiguous atrioventricular (A-V) valves. The two dimensional echocardiographic criteria used to identify a chamber as having right morphology were (1) an irregular endocardial surface, (2) insertion of chordae tendineae into the ventricular septum, (3) presence of an infundibulum, (4) a triangular-shaped ventricular cavity, (5) observation of a moderator band, and (6) recognition of the A-V valve as tricuspid. The two dimensional echocardiographic criteria for a left ventricular morphology were (1) a smooth endocardial surface, (2) presence of two discrete papillary muscle groups, (3) an ellipsoid-shaped ventricular cavity, and (4) recognition of the A-V valve as mitral. Identification of the associated A-V valve as mitral or tricuspid was the most reliable criterion, defining each ventricle in all 19 patients. The nature of chordal attachment and papillary muscle insertion successfully identified all left-sided and posteriorly related ventricles and 9 of the 19 anterior ventricular chambers. Other criteria were less useful although, when observed, they confirmed the ventricular type.

Adolescent↗
PubMed1982

Infants born before 29 weeks gestation: survival and morbidity at 2 years of age.

In a collaborative study involving two hospitals with large maternity services, 166 liveborn infants of gestational age from 24 to 28 weeks were born in the calendar years 1977 and 1978. Of these infants, 75 (45.2%) died either in hospital or after discharge home. At the age of 2 years, 16 (9.6%) of the cohort had a major handicap [cerebral palsy, Mental Developmental Index (MDI) under 69, deafness or blindness]. An additional 20 children (12.0%) had significant developmental delay (MDI 69 to 84, -2 to -1 SD below mean) and 53 (31.9%) were considered to be free of these handicaps. Psychological assessments were not performed on two survivors (1.2%) but reliable reports indicated that they were free of major handicaps. Long-term survival increased in a stepwise fashion from 9.1% at 24 weeks to 68.5% at 28 weeks gestation, and there was a trend for major handicap and significant developmental delay to decrease in incidence with increasing maturity. Of the 58 children who had presented by the vertex 42 (72.4%) were free of significant handicap; however, of the 31 children in whom there had been either a breech presentation or a transverse lie, only 11 (35.5%) were free of significant handicap (chi 2 = 9.69, P less than 0.01). The mode of delivery (vaginal or caesarean section) did not significantly affect the handicap rate in the survivors.

Australia↗
PubMed1982

Influence of R wave analysis upon diagnostic accuracy of exercise testing in women.

Exercise electrocardiography in women with chest pain is associated with a high incidence of false positive ST segment depression. The recent observation that changes in R wave amplitude during exercise can also be used diagnostically may improve the value of stress testing in women. The results of 12 lead treadmill exercise and coronary angiography were reviewed in 62 women, mean age 51 years, presenting with "angina" without previous myocardial infarction. These were compared with exercise results in 14 healthy asymptomatic volunteers with a mean age of 26 years. In addition to conventional ST analysis, R wave amplitude changes during exercise, measured in leads II, III, a VF, and V4 to 6, were examined. While the sensitivity and specificity of ST and R wave changes were similar at about 67%, their combined interpretation was helpful. If both ST and R wave criteria were negative the predictive accuracy for normal coronary angiography was 94% (17/18). Alternatively, in tests showing both ST depression and an abnormal R wave response, coronary angiography was always abnormal (13/13). None of the normal volunteers developed ST segment depression and 93% (13/14) had a normal R wave response. If both were positive, however, coronary angiography was always abnormal (13/13). Although stress test interpretation in women is difficult, R wave analysis is a useful adjunct to ST change and can improve the predictive accuracy of the test in a significant number of patients.

Adult↗
PubMed1982

Changing outcome over 13 years of very low birthweight infants.

The survival prospects for infants of birthweight less than or equal to 1500 g born in recent years have improved. Evidence for a corresponding decrease in long-term morbidity of survivors is conflicting but recent reports from some centers indicate that high morbidity rates are occurring. Until additional satisfactory reports are available on the outcome of very low birthweight (VLBW) infants born after 1975, preferably from a community or region, uncertainty will continue. The outcome of three cohorts of VLBW infants, born in the Royal Women's Hospital, Melbourne between 1966 and 1978 is reported; more than 90% of each cohort were fully assessed, aged 2-8 years. There were 169 long-term survivors from the first cohort (1966-1970 births) and 72 from the second cohort (1973-74 births); survival rates were 37.1% and 37.3% respectively; however, for the 1977-78 births, there were 161 survivors, a significant increase to 68.3%. In the first cohort, 32.7% had one or more visual defects and 3.9% were blind but visual morbidity decreased progressively in cohorts 2 and 3; 3% of the second cohort and 1.2% of the third cohort were blind. There was a trend for a decrease in severe sensorineural deafness. Cerebral palsy increased progressively, respectively 2.6%, 4.5% and 11.9% in the first, second and third cohorts. There was a significant increase in the mean Mental Developmental Index of the Bayley Scales at the age of 2 years from 75.38 for the 64 children born in 1966-70 compared with 90.96 for 150 children in the 1977-78 cohort. Although there had been an increase in upper social class families in the more recent cohort, improvement in test scores was still highly significant when higher social classes (1-3 Congalton Scale) were excluded. However, there was no significant improvement in the 6 year psychological test scores of the first and second cohorts. There was a steady increase in occurrence of cerebral palsy. Significance associations in the 1977-78 cohort were found with only 2 perinatal variables (use of theophylline and necrotizing entercolitis). Furthermore, 17 (89.5%) of children had a five-minute Apgar score greater than 5 and 14 (73.7%) did not require ventilatory support: Prevention of cerebral palsy by selective treatment in the delivery room or nursery was not feasible for prediction of this condition was not possible from perinatal risk factors.

Australia↗
PubMed1981

R-wave amplitude and left ventricular volume: changes with nitroglycerine and atrial pacing.

The relationship between R-wave amplitude and left ventricular volume was examined using two groups of patients, undergoing diagnostic cardiac catheterisation for investigation of chest pain, who had simultaneous R-wave recording and left ventricular angiography. R-wave amplitude was measured in leads 1, 2, 3 and V4-6. Left ventricular volume was altered by nitroglycerine (n = 18) and atrial pacing (n = 13). In both groups, increase or decrease in left ventricular volume was associated with a concomitant change of R-wave amplitude. We conclude that left ventricular volume is an important determinant of surface-recorded R waves with increased amplitude reflecting increased left ventricular volume and vice versa.

Angiography↗
PubMed1980

A longitudinal study of very low-birthweight infants. IV: An overview of performance at eight years of age.

A cohort of 169 very low-birthweight infants (800 to 1500g) was followed prospectively to the age of eight years. Information on 159 of the children was available at that age, and for a further five to the age of six years. A comparison group of 67 normal-birthweight children was also followed, but only 43 of these children were seen at the age of eight years. Eight of the very low-birthweight (VLBW) children were attending special schools and 156 attended normal schools: placement of the remaining five was unknown. Of the VLBW children who were adequately assessed, 15.9 per cent were either not reading or were retarded by more than 18 months. Mean VLBW full-scale IQ was 88.8, compared with 98.8 for the normal-birthweight group. A subgroup of 10 VLBW children with birthweights under 1000g had lower mean scores on all three WISC-R scales compared with those with birthweights between 1000 and 1500g. Of the adequately assessed VLBW children, 3.7 per cent had epilepsy, 3.7 per cent had significant sensorineural deafness and 2.4 per cent suffered from cerebral palsy. One or more visual defects were detected in 31.4 per cent of the children, though in only 3.8 per cent was the defect serious. At eight years, growth dimensions for the VLBW children were below the 10th percentile for 11.0 per cent in weight, 16.1 per cent in height and 15.0 per cent in head circumference. Degrees of handicap in the VLBW children were profound in 5.1 per cent, severe in 10.8 per cent and significant in 40.5 per cent: handicap was minimal or absent in the remaining 43.6 per cent. For the normal-birthweight group the percentages were 2.3, 0, 25.6 and 72.1 respectively. The VLBW children with minimal or no handicap were considered to have a satisfactory outcome. This was significantly correlated with the following: gestation over 30 weeks; birthweight over 1199g; no major apnoeic attacks; lowest postnatal weight before six days; return to birth weight before 21 days; peak serum bilirubin not exceeding 255 mumol/litre; and parental social-class between 2 and 5 on the seven-point Congalton Scale.

Child↗
PubMed1980

Clinical classification of generator and electrode failures.

A clinically based failure classification system is suggested for cardiac pacing generators and electrodes, and the method of reporting actuarial survival is reviewed. The difficulties of calculating potential generator lifetimes and the consequent definition of premature generator failures are discussed and a pragmatic solution is offered.

Electric Power Supplies↗
PubMed1979

Influence of preoperative left ventricular function on results of homograft replacement of the aortic valve for aortic stenosis.

The effect of preoperative left ventricular function on early and late prognosis was assessed in 103 patients with aortic stenosis who underwent left ventricular cineangiography before homograft replacement of the aortic valve. The patients were separated into two groups: Group A (58 patients) with an ejection fraction of 0.46 or more and Group B (45 patients) with an ejection fraction of 0.45 or less. The two groups were compared with respect to clinical and hemodynamic data as well as operative result. There was poor correlation between clinical data and left ventricular function. In Group A there were three early deaths (5.2 percent) and three late deaths (5.2 percent) compared with no early and six late deaths (13.3 percent) in Group B during the follow-up period of 12 to 102 months (mean 43 months). Most patients in Group B showed considerable symptomatic improvement but less than that observed in Group A. Forty-two patients (13 in Group A and 29 in Group B) underwent repeat cardiac catheterization and coronary angiography. Improvement in left ventricular function as assessed by radial analysis of segmental wall motion and ejection fraction was observed in 20 of the 29 patients in Group B. Failure of left ventricular function to improve was associated with additional coronary artery disease in the majority of patients. It is concluded that poor left ventricular function does not increase the risk of aortic valve replacement for aortic stenosis and that improvement in left ventricular function can be expected in the majority of patients.

Adolescent↗
PubMed1979

Influence of preoperative left ventricular function on results of homograft replacement of the aortic valve for aortic regurgitation.

The effect of preoperative left ventricular function on eraly and late prognosis was assessed in 69 patients with aortic regurgitation who underwent homograft replacement of the aortic valve. Patients were divided into two groups: Group A (38 patients) had an ejection fraction of 0.46 or more and Group B (31 patients) had an ejection fraction of 0.45 or less. Clinical data, hemodynamic data, and operative results were compared in the two groups. In Group A there was one early death (2.6%) and there were two late deaths (5.3%) compared to two early deaths (6.5%) and seven late deaths (22.6%) in Group B during a follow-up period of 13 to 98 months (mean, 49 months). Actuarial analysis showed a 94% survival at 6 years in Group A compared to 80% in Group B. Twenty-four patients were reinvestigated by repeat cardiac catheterization and coronary angiography at a mean time of 38 months following valve replacement. Left ventricular function was assessed by computerized quantitative radial analysis of segmental wall motion. Improvement in left ventricular function occurred in eight of the 14 patients reinvestigated in Group B, and appeared to be closely related to the etiology of the initial valve lesion. Despite the higher mortality rate in patients with poor left ventricular function, most derived considerable benefit from operation.

Adolescent↗
PubMed1977

The assessment of regional abnormalities of the left ventricle by angiography.

A method of regional wall motion analysis of left ventricular cineangiograms which does not make assumptions about ventricular geometry is described. The technique measures the movement of the ventricular perimeter in relation to the geometric center of gravity of the endsystolic frame expressing movement as a change in radical length. 10 control patinets each with 3 left ventricular cineangiograms, comprise the group for definition of normal values of movement and permit estimations of reproducibility within and across patient groups. Isolated examples of abnormal wall motion are shown.

Adult↗
PubMed1976

Transposition of the great arteries: logical anatomical arterial correction.

In a 20-month-old child with classic transposition of the great arteries the pulmonary artery, coronary arteries, and aorta were successfully retransposed at arterial level. It was difficult to reimplant the coronary arteries in the dilated pulmonary artery root without damaging the attachments of the valve cusps, and it may be better to divide the pulmonary artery first to avoid this hazard. Retransposition at arterial level will not be suitable for all patients with transposition of the great arteries, and many questions about long-term outcome remain to be answered.

Aorta, Thoracic↗