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Biomedical subjects

R Foale

Publications and source records attributed to R Foale.

At least 37 records · Page 2Linked to original sources
PubMed1994

Restrictive cardiomyopathies.

Restrictive cardiomyopathy has always been a fairly common cause of cardiac death in the tropics through endomyocardial fibrosis. In temperate climates, amyloidosis is the most common form of the disease, whereas Löffler's endocarditis is quite rare. Amyloidosis is more frequently encountered as the population ages, but restrictive cardiomyopathy is still rare outside the tropics. Differentiation between cardiac restriction and constriction is still the major clinical consideration as treatment for constrictive pericarditis is easily administered.

Amyloidosis↗
PubMed1994

Cardiovascular effects of growth hormone replacement therapy in hypopituitary adults.

In the present study the effects of replacement with biosynthetic human growth hormone (GH) in a large group of hypopituitary adults on cardiac structure and function were investigated. Thirty-six GH-deficient, hypopituitary patients (17 males and 19 females; aged 19-67 years) on conventional replacement therapy without GH were studied. Twenty-nine of the patients had acquired hypopituitarism in adult life, mainly due to pituitary tumours. The design of the study was a prospective, randomized, double-blind placebo-controlled trial for 6 months. Growth hormone (17 patients) was given in a daily dose of 0.02-0.05 IU/kg body wt sc (or a placebo, 19 patients) according to the patients' tolerance. Other pituitary replacement treatment was unchanged. Resting and exercise electrocardiography using the Bruce protocol, two-dimensional echocardiography, Doppler ultrasound scanning and serum insulin-like growth factor I (IGF-I) were assessed at 0 and 6 months. Resting blood pressure was measured at 0, 1, 3 and 6 months. Serum IGF-I increased significantly on GH treatment (mean +/- SD) GH: 293 +/- 197 vs placebo: 82 +/- 40 micrograms/l; p < 0.0001 at 6 months). Exercise time increased significantly on GH but not on placebo (GH: 8.45 +/- 3.16 to 9.38 +/- 2.42 min.sec, p < 0.01; placebo 9.08 +/- 4.35 to 9.50 +/- 4.14 min.sec, NS), although the change was not significantly different between the two. There was no change in the heart rate or the blood pressure either at rest or at the peak of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effectiveness and safety of a single intravenous bolus injection of tissue-type plasminogen activator in acute myocardial infarction. Bolus Dose-Escalation Study of Tissue-Type Plasminogen Activator (BEST) Investigators.

The efficacy of multiple intravenous bolus injections of tissue-type plasminogen activator (t-PA) in inducing rapid coronary recanalization in patients with acute myocardial infarction was previously demonstrated. In this Bolus Dose-Escalation Study of Tissue-Type Plasminogen Activator (BEST), the efficacy of 3 different doses of a single rapid intravenous bolus injection of t-PA (dute-plase, Wellcome Foundation, London) in inducing coronary patency (Thrombolysis In Myocardial Infarction perfusion grade 2 or 3) in 64 patients with acute myocardial infarction presenting less than 6 hours after onset of symptoms was investigated. At 60 minutes after administration of t-PA, the infarct-related coronary artery was patent in 9 of 17 patients (53%; 95% confidence interval [CI] 28 to 77%) after 0.3 MU/kg, in 14 of 23 (61%; 95% CI 39 to 80%) after 0.45 MU/kg and in 10 of 14 (71%; 95% CI 42 to 92%) after 0.6 MU/kg. At 90 minutes after t-PA, coronary patency was present in 9 of 17 cases (53%; 95% CI 28 to 77%) after 0.3 MU/kg, in 12 of 24 (50%; 95% CI 29 to 71%) after 0.45 MU/kg and in 10 of 13 (77%; 95% CI 46 to 95%) after 0.6 MU/kg. One patient in each dose group had a silent reoccluded infarct-related artery by 24 hours, and there were 2 clinical reinfarctions before discharge. No major bleeding events were observed. There were 5 hospital deaths, all unrelated to t-PA. A single intravenous bolus injection of 0.6 MU/kg of t-PA appears to be effective in inducing rapid coronary patency and to be safe in patients with acute myocardial infarction.

Adult↗
PubMed1990

Cross sectional echocardiographic identification of hypoplastic left heart syndrome and differentiation from other causes of right ventricular overload.

To identify the echocardiographic features that can be used to distinguish between hypoplastic left heart syndrome and other causes of right ventricular overload in the sick neonate cross sectional echocardiographic studies of 10 neonates with hypoplastic left heart syndrome were analysed and compared with those in 15 neonates with other causes of right ventricular overload and 15 normal controls. Left ventricular and right ventricular cavity dimensions and the shape and size of the mitral valve annulus and aortic root were recorded and presented both as absolute values (mm) and corrected for body surface area (mm/m2). Logistic regression was used to produce a classification rule to estimate the probability of a neonate having hypoplastic left heart syndrome. The diameter of the mitral valve annulus was the single most discriminative variable. There was, however, considerable overlap of all the calculated features between neonates with hypoplastic left heart syndrome and those with other causes of right ventricular overload. The diagnosis of hypoplastic left heart syndrome should not be based on any one single echocardiographic feature but the general appearance of abnormal left heart valves, small cavity dimensions, and the size of the mitral valve annulus.

Anthropometry↗
PubMed1989

Functional relation between infarct thickness and regional systolic function in the acutely and subacutely infarcted canine left ventricle.

Specific information regarding the relation between infarct thickness and regional systolic function is important to the overall understanding of both the pathophysiology of acute and subacute myocardial infarction and the functional benefits of myocardial salvage interventions designed to limit the transmural extent of infarction and thereby preserve left ventricular function. In the present study, quantitative computer-assisted two-dimensional echocardiography was used to define the relation between infarct thickness and systolic function in the acutely and subacutely infarcted canine left ventricle. Echocardiograms were obtained at the mid-papillary muscle level at baseline and 6 h after occlusion (acute infarction) in eight animals and at baseline and 72 h after occlusion (subacute infarction) in nine animals. Systolic function was assessed by measuring the extent of fractional radial shortening along each of 36 evenly spaced endocardial targets from end-diastole to end-systole; the transmural extent of infarction was determined from the triphenyltetrazolium chloride-staining deficit at 6 and 72 h. The relation between systolic function and transmural extent of infarction was analyzed in two ways. First, the extent of fractional radial shortening in each group was examined as a function of quartile (25%) increments in transmural infarct thickness. This analysis revealed 1) a significant overall loss of fractional radial shortening with increasing transmural extent of infarction in both groups; and 2) significant differences in the extent of systolic dysfunction between successive quartile increments of infarction. Second, the relation between infarct thickness and systolic dysfunction was modeled mathematically by fitting the data from each infarct series to linear, logarithmic and exponential functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Echocardiographic measurement of right ventricular wall thickness in hypertrophic cardiomyopathy: relation to clinical and prognostic features.

Hypertrophic cardiomyopathy is characterized by unexplained left ventricular hypertrophy. It is uncertain, however, to what extent the right ventricle is also thickened. Right ventricular hypertrophy is found at autopsy in patients who die suddenly but, until recently, systematic evaluation of right ventricular morphology has not been feasible. In this two-dimensional echocardiographic study, a total of 4 to 10 (median 7) right ventricular wall thickness measurements were made from six right ventricular views in 73 patients with hypertrophic cardiomyopathy. Forty-one normal subjects were also studied for comparison. Thirty-two (44%) of the 73 patients had right ventricular hypertrophy with at least two of the wall thickness measurements exceeding 2 standard deviations (SD) from the mean value in the normal subjects. Right ventricular hypertrophy was mild (less than or equal to 8 mm) in 24 patients, moderate (9 to 12 mm) in 7 and severe (greater than 12 mm) in 1. The coefficient of variation of right ventricular wall thickness measurements was similar in normal subjects and patients with and without right ventricular hypertrophy (17 +/- 7, 11 +/- 8 and 10 +/- 8, respectively). The hypertrophy was concentric, with a coefficient of variation of 25% in all but one patient. There was a strong correlation of maximal right and mean left ventricular wall thickness (r = 0.643, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Accuracy of two-dimensional echocardiography in the diagnosis of aortic arch obstruction.

To evaluate the predictive accuracy of two-dimensional echocardiography in the diagnosis of aortic arch obstruction, 540 consecutive patients aged 2 days to 15 years (mean 2 months) who underwent subsequent cardiac catheterization and angiography were prospectively studied. At angiography, 51 patients had aortic arch obstruction; of these, 35 had juxtaductal coarctation, 15 isthmic hypoplasia and 1 a type B interrupted aortic arch. The presence of arch obstruction was correctly identified with two-dimensional echocardiography in 45 of 51 patients with this condition (overall sensitivity 88%). Two-dimensional echocardiography clearly defined a juxtaductal coarctation in 33 of 35 patients and isthmic hypoplasia in 13 of 15 patients (sensitivity 94% and 73%, respectively). The form and type of interrupted aortic arch were clearly distinguished from other forms and types of arch obstruction. Among the 489 patients without aortic arch obstruction, two-dimensional echocardiography wrongly diagnosed the presence of such obstruction in 9 patients (overall specificity 98%). Forty-six (92%) of the 51 patients had at least one associated intracardiac abnormality. Twenty-two (44%) had a ventricular septal defect, 21 (42%) a bicuspid aortic valve and 4 (18%) subaortic stenosis. Five patients had complex congenital cardiac malformations. All associated abnormalities were prospectively identified with two-dimensional echocardiography. Thus, two-dimensional echocardiography is highly specific in diagnosing aortic arch obstruction. It is less sensitive for the diagnosis of isthmic hypoplasia in the neonatal period.

Adolescent↗
PubMed1986

Echocardiographic assessment of the right ventricle in Ebstein's anomaly: relation to clinical outcome.

Two-dimensional echocardiography was performed in 16 patients with Ebstein's anomaly to assess right ventricular anatomy and function in relation to clinical features and prognosis. Measurements of right ventricular anatomy and function were established in 10 normal subjects for comparison. Ten patients were in New York Heart Association functional class I, four in class II and one each in classes III and IV. Right ventricular morphology and the three tricuspid valve leaflets were assessed from right ventricular inflow tract and apical four chamber views. The anterior tricuspid leaflet was abnormal but not displaced in all patients; the septal and posterior leaflets were displaced in 14 (88%) and 11 (69%) patients respectively. The posterior leaflet was best visualized from the right ventricular inflow tract, and in two patients this view was required for the echocardiographic diagnosis of Ebstein's anomaly, based on displacement of the septal tricuspid valve leaflet. An index of right ventricular function, the fractional area contraction, was defined as the difference between the end-diastolic and the end-systolic area, normalized to the end-diastolic area. This index was calculated for both the proximal (atrialized) right ventricle and the total right ventricle. Total right ventricular end-diastolic area and fractional area contraction exceeded 95% confidence limits when compared with values in the normal group. During a median follow-up period of 4 years three patients died. They had severe right heart morphologic or functional abnormalities; two were in functional class III or IV and one was asymptomatic. None of the survivors had severe symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Echocardiographic measurement of the normal adult right ventricle.

In studies of the right ventricle the complexities of chamber shape may be overcome by use of multiple tomographic imaging planes. An established protocol for the echocardiographic description of the heart was used to examine the right ventricle in an ordered series of transducer locations and orientations. Diastolic measurements were made of the right ventricular inflow tract, outflow tract, and right ventricular body, and the range and reproducibility of normal values for cavity size and right ventricular free wall thickness were established. These measurements of cavity size in 41 normal subjects were highly reproducible and the views that were used correctly described the truncated and ellipsoidal shape of the right ventricular inflow tract and body with a separately aligned outflow tract. Cavity trabeculation prevented measurement of the free wall thickness in some areas; however, values of nearly twice the previously reported upper limit of normal for anterior regions were measured from the apex or lateral right ventricular wall. These normal data provide a basis for future echocardiographic studies of the right ventricle.

Adult↗
PubMed1986

Regional myocardial and organ blood flow after myocardial infarction: application of the microsphere principle in man.

A physiologic means of measuring the distribution of cardiac output and regional myocardial blood flow has been developed that uses human albumin microspheres labeled with carbon-11 (11C) and external detection with positron emission tomography. Ten patients with previous myocardial infarction were studied to investigate the level of blood flow in normal and infarcted segments of the heart. After diagnostic catheterization, 4 to 6 mCi of 11C on 2 to 3 million sterile microspheres (15 to 20 micron) were mixed and injected into the apex of the left ventricle during timed withdrawal of arterial blood to obtain reference flow values. Regional activity in brain, heart, lungs, liver, spleen, and kidneys was measured tomographically. Blood flow was calculated based on the relationship between total activity in a reference flow and tissue activity in tomograms of each organ (ml/min/100 g). No adverse effects were noted after injection of the microspheres. Successive myocardial tomograms showed no loss of activity. There were no significant differences in flow values in matched regions of paired organs. Mean cerebral flow was 52.4 +/- 10.0 ml/min/100 g in the frontal lobes, 54.4 +/- 8.8 in the temporal lobes, 67.6 +/- 8.2 in the occipital lobes, and 53.0 +/- 9.4 in the basal ganglia. Flow was 16.0 +/- 8.4 ml/min/100 g (range 0 to 40.0) in the center of infarcted myocardium and 82.0 +/- 32.0 in the remote segments. This method meets most of the demands for use of microspheres to measure tissue blood flow. The wide range of flow values in infarcted myocardium may be a function of infarct size, spatial resolution, or pathologic evidence of islands of viable tissue. Patients with angina had high flow values in the infarcted segment, whereas those with heart failure had significantly lower values. Surviving myocardium in the region of the infarct may need to be considered if patients complain of angina, particularly when treatment is aimed at preserving ventricular function.

Adult↗
PubMed1985

Intracardiac contrast echoes during transvenous His bundle ablation.

Two patients undergoing endocavitary ablation for resistant supraventricular tachycardia had cross sectional echocardiography performed during the ablative procedure. In both cases immediate opacification of the right heart cavities occurred at the time of the current discharge. The contrast effect was similar to that resulting from a peripheral venous injection of dextrose or saline during echocardiography for the diagnosis of intracardiac shunts. In one patient contrast echoes were also seen in the left ventricle. This contrast effect may be produced by gaseous release or blood element destruction. The risk of embolisation in patients undergoing endocavitary ablation, particularly on the left side of the heart, should be further evaluated.

Adult↗
PubMed1983

Cross-sectional echocardiographic features of ruptured chordae tendineae.

Thirty-two patients with mitral regurgitation secondary to ruptured chordae tendineae were studied by cross-sectional echocardiography. Twenty of them subsequently underwent operation. Three signs are described. (1) Non-coaptation of the leaflets (55%). (2) Systolic fluttering echo in the left atrium originating from the mitral valve (20%). (3) A previously not described small diastolic chaotically moving echo in the short axis section of the left ventricle at the level of the papillary muscles (65%). The combined sensitivity of these three signs was 85%. The specificity of the three signs when compared with those of 107 patients with mitral regurgitation of different aetiologies studied by cross-sectional echocardiography was 99%, 100% and 99%, respectively. Six patients were studied after mitral valve repair; restriction of the surgical treated leaflet and reduction of its valve area was seen in all of them, and the disappearance of the valvar signs of ruptured chordae noted. The persistence of the small echo sign in the short axis of the left ventricle indicated its chordal origin.

Chordae Tendineae↗
PubMed1983

Anomalous systemic venous return: recognition by two-dimensional echocardiography.

The two-dimensional echocardiographic features of anomalies of systemic and coronary venous return are described as they were seen in 23 patients with this diagnosis proven at angiography. A left-sided superior vena cava draining to the right atrium via an enlarged coronary sinus was correctly identified in all 17 patients with this condition by observing a characteristically moving ovoid structure in the region of the posterior atrioventricular groove. This structure opacified before the right side of the heart following bolus injections of contrast material from a left arm vein. Injection from the right arm in 12 patients or femoral vein in four patients of this group produced contrast echoes within the right heart only. A left-sided superior vena cava draining directly to a left atrium in three patients, or left side of a common atrium in two patients with atrial situs inversus, was identified by the immediate opacification of the left-sided chamber following injection from the left arm. Two patients with hemiazygos inferior vena caval return to the left superior vena cava or left atrium were studied using injections of contrast from the femoral vein which successfully identified the venous abnormality. Two-dimensional echocardiography, when combined with peripheral venous injections of contrast will reliably demonstrate anomalies of systemic venous return, and thus provides important information before more invasive procedures.

Adolescent↗
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↗
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

Echocardiographic features of eosinophilic endomyocardial disease.

Nine patients with eosinophilic endomyocardial disease who had undergone angiocardiography with histological staging of their disease, were studied by M-mode and two dimensional echocardiography to determine the extent to which specific features of the disease could be evaluated by these non-invasive methods. In seven patients, amplitude processed two dimensional echocardiography showed regions where the relative intensity of endomyocardial echoes was greater than normal, and their distribution corresponded to known areas of fibrosis. Standard two dimensional echocardiography was normal in all but three patients. In eight patients M-mode echocardiography showed only non-specific abnormalities, but appeared to be useful in assessing the functional consequences of myocardial or mitral valve disease. After digitisation a reduction in the duration and an increase in the peak rate of dimension increase during filling was prolonged. It was concluded that amplitude processed two dimensional echocardiography might be useful in diagnosing the extent and severity of endomyocardial disease in patients with hyperosinophilia. These noninvasive techniques may thus provide a means for the early diagnosis of endomyocardial fibrosis and could be useful in assessing in progression or response to treatment.

Adult↗