Biomedical subjects
Publications and source records attributed to G R Sutherland.
Eleven years after surgical repair of pulmonary atresia with a ventricular septal defect with a valved conduit, a 20 year old patient was diagnosed on follow up echocardiography to have a right ventricular pseudoaneurysm related to the conduit. The echocardiographic findings were confirmed at reoperation and the pseudoaneurysm was excised.
The total surgical experience of a supraregional paediatric cardiology unit over a nine year period (January 1980 to December 1988) was reviewed to assess the effect of the introduction of the full range of ultrasound techniques. A total of 1517 patients underwent cardiac surgery (955 cardiopulmonary bypass, 562 closed procedures). Of these, 485 patients (32%) did not undergo cardiac catheterisation before operation: 217 bypass (23% of all procedures under cardiopulmonary bypass) and 268 closed procedures (48%). The overall ratio of catheterisations to operations for patients undergoing palliative or corrective surgery fell from 0.97 (1980) to 0.38 (1988). The patients were classified as (a) neonates (0-28 days), (b) infants (one to 12 months), and (c) children (one to 14 years). The main impact of non-invasive surgical referral was in neonates (total catheter:operation ratio 0.38; neonates 0.2 for 1988). The surgical population was further divided according to the principal echocardiographic technique available: (a) 1980-4 cross sectional imaging; (b) 1985-6; imaging plus spectral Doppler ultrasound; (c) 1987-8; imaging plus spectral Doppler ultrasound and colour flow mapping. A fall in the catheter:operation ratio for all age groups was most pronounced in the last four years. This reflects increased familiarity and surgical confidence with non-invasive diagnostic assessment. The introduction of each new echocardiographic technique was associated with a significant fall in the total catheter:operation ratio compared with the preceding period. Six incorrect ultrasound diagnoses were made during the entire period; one of these patients died in the early postoperative period. The integration of Doppler ultrasound with cross sectional imaging has made non-invasive assessment an increasingly practical alternative to preoperative cardiac catheterization.
Transoesophageal echocardiographic imaging in the longitudinal axis is a recent addition to the non-invasive evaluation of congenital and acquired heart disease. The technique provides unique images of intracardiac anatomy but their interpretation remains difficult. A heart specimen was therefore cut according to the echocardiographic imaging planes to elucidate the morphological details. The results suggested that longitudinal transoesophageal imaging complements the transverse axis approach. It gave new imaging information on the right ventricular outflow tract and the pulmonary trunk, the atrioventricular valves, the interventricular septum, the cardiac apex, and the thoracic aorta. In particular, it showed the entire length of the right ventricular outflow tract. When longitudinal imaging was used in combination with transverse imaging almost all the thoracic aorta could be examined. Imaging in the longitudinal axis may also allow better assessment of the mechanisms of atrioventricular valve regurgitation.
The human type II collagen gene (COL2A1) was mapped to chromosome 12 immediately proximal to fra(12)(q13.1) by the technique of nonisotopic (biotinylated) in situ hybridization. Thus, the COL2A1 gene was confirmed to be at the subband 12q13.11----q13.12, in agreement with previous reports. These results are not in agreement with the localization (12q14.3) cited in Ropers and Craig (1989).
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Pulmonary capillary wedge pressure (PCWP) is monitored during anesthesia in an attempt to detect changes in myocardial function in patients at risk of preoperative cardiac complications. Because the sensitivity with which preoperative PCWP monitoring indicates myocardial ischemia is uncertain, we monitored PCWP, 12-lead electrocardiogram, and left ventricular wall motion abnormalities as defined by transesophageal echocardiography (TEE) in 98 anesthetized patients before coronary artery bypass grafting. Measurements were made five times in each patient, before and after induction of anesthesia. Myocardial ischemia was identified by TEE in 14 patients; in 10 of these, it was associated with concomitant ST segment depression of at least 1 mm. The onset of ischemia, as defined by TEE, was accompanied by a mean increase in PCWP of 3.5 +/- 4.8 mm Hg, as compared with a mean change of 0 +/- 2.2 mm Hg between observations not associated with the onset of ischemia (p less than 0.01). An increase in PCWP of at least 3 mm Hg, tested as an indicator of ischemia, had a sensitivity of 25% and a positive predictive value of 15%; after correction for background changes associated with anesthetic induction, the sensitivity of this indicator was 33%, and its positive predictive value was 16%. These figures were not improved by selecting cutoff points higher or lower than 3 mm Hg. In this study, the onset of myocardial ischemia was associated with a small yet significant increase in mean PCWP at group level.(ABSTRACT TRUNCATED AT 250 WORDS)
Using both precordial and transesophageal echocardiography, we studied 72 consecutive patients with a recent unequivocal transient ischemic attack or nondisabling stroke to determine the relative value of the two techniques for detecting potential intracardiac sources of cerebral emboli. Group 1 (n = 53) patients had no clinical cardiac abnormality, and group 2 (n = 19) patients had abnormal cardiac findings upon clinical examination. In group 1, precordial echocardiography detected an abnormality in only one patient (aortic valve thickening) but transesophageal echocardiography defined morphologic abnormalities in five patients (one with a left atrial appendage mass lesion, one with aortic dissection, one with mitral valve prolapse, one with a mitral leaflet mass lesion, and one with aortic valve thickening). In group 2, both precordial and transesophageal echocardiographic studies were normal in 13 patients, while both were abnormal in the remaining six patients. Five of these six patients had pathologic left atrial and/or left ventricular dilatation, but only transesophageal echocardiography defined a left atrial appendage thrombus in two of the six. The sixth patient had mitral chordal rupture, seen on both precordial and transesophageal echocardiography. In addition, in 32 of the 72 patients transesophageal echocardiography identified widespread thoracic aortic atherosclerotic plaques not visualized by precordial echocardiography. We conclude that transesophageal echocardiography significantly increases the yield in visualizing potential intracardiac sources of emboli compared with precordial echocardiography. However, the precise clinical value of the former in the management of such patients requires further study as the number of abnormal transesophageal echocardiographic findings is not high and a causative relation with transient ischemic attacks cannot be proven.
Although the computer is now becoming more common in radiology departments, where its application is generally in the field of assisting in the operational effectiveness of the department at a clerical and secretarial level, the implementation of the White Paper "Working for Patients" will make it increasingly important for the radiologist in charge of a department and the superintendent radiographer to have the facts and figures of the operation of the department at their fingertips. This will be to the benefit of our patients, as it can only lead to an improvement in the effectiveness of our activities. Such information will also give us greater confidence in discussion with clinical colleagues, by providing specific facts relating to unrealistic use of the services we provide.
Two apparent deletions of the short arm of chromosome 16 were studied by in situ hybridisation using biotinylated DNA from a chromosome 16 specific cosmid library (chromosome painting). One abnormality was delineated as a t(1;16)(p36;p12) and the other as a ins(11;16)(q13;p13.13p13.3). Apparently unbalanced de novo abnormalities detected by classical cytogenetic procedures should be interpreted with caution. In situ hybridization using DNA from chromosome specific libraries provides the appropriate technology to delineate such abnormalities.
A small probe for cardiac surgery was developed and clinically tested. The probe is built as a phased array transducer with 64 elements with a centerfrequency of 5 MHz. The transducertip is connected with a handle by a flexible yet steerable shaft. This shaft has a length of 10 cm and can be set in a desired shape. Good quality images were obtained in all patients. The first study suggest many applications for a small probe in intraoperative echocardiography.
The lysosomal hydrolase alpha-L-iduronidase (IDUA) is one of the enzymes in the metabolic pathway responsible for the degradation of the glycosaminoglycans heparan sulfate and dermatan sulfate. In humans a deficiency of IDUA leads to the accumulation of glycosaminoglycans, resulting in the lysosomal storage disorder mucopolysaccharidosis type I. A genomic subclone and a cDNA clone encoding human IDUA were used to localize IDUA to chromosome 4p16.3 by in situ hybridization and this was confirmed by Southern blot analysis. This localization is different from that of a previous report mapping IDUA to chromosome 22 and places the gene for IDUA in the same region of chromosome 4 as the Huntington disease gene. Measurement of expressed human IDUA activity in human-mouse hybrid cell lines confirmed that IDUA is on chromosome 4.
The acute hemodynamic and echocardiographic effects of pericardial closure on cardiac function were studied in 11 pigs during steady-state anesthesia and ventilation. Observations were made after sternotomy, both while the pericardium was open and after it had been closed, and then after closure of the chest, after the pericardium had been reopened by removing the pericardial suture through the chest wall. In five pigs, further observations were made when a suture was tightened to close the pericardium while the chest remained closed. Closure of the pericardium when the chest was open reduced cardiac output by 14% and mean stroke volume by 19% (both p less than 0.05). Systemic vascular resistance increased by 15% when the pericardium was closed while the chest was open (NS), and increased by 19% when it was closed while the chest was closed (p less than 0.05). Heart rate did not change significantly, and the systemic blood pressure was maintained (-8%, NS). All these effects were reversed by opening the pericardium. Intrathoracic epicardial echocardiographic monitoring of the left ventricle showed that its end-diastolic dimension increased (by 11%, p less than 0.05) when the pericardium was opened. After chest closure, paradoxical motion of the interventricular septum was consistently demonstrated only during ventilation, and it was not related to whether or not the pericardium was open. This study suggests that cardiac function may be impaired by pericardial closure after cardiac surgery because of some degree of constriction of the heart chambers, although acute circulatory responses compensate for the mild decrease in stroke volume. Monitoring of blood pressure alone cannot document the subtle circulatory changes induced by pericardial closure, and therefore it is not a reliable guide to decisions of whether to close the pericardium or leave it open in individual patients.
The gene for erythroid 5-aminolevulinate synthase has been mapped to Xpter-Xq26 by Southern blot hybridization analysis of a mouse/human hybrid cell panel. In situ hybridization maps the gene to Xp21-Xq21, with the most likely location being on band Xp11.2. The mapping of the erythroid 5-amino-levulinate synthase gene to the X chromosome suggests that a defect in this gene may be the primary cause of X-linked sideroblastic anemia.
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A combination of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) has been used to follow the time course of changes resulting from forebrain ischemia in the rat. The 31P MRS demonstrates that the level of high energy metabolites decreases significantly during the 10 min ischemic period but returns to normal after 1 h of reperfusion. MRI shows no change after 1 h of reperfusion but significant changes in the striatum after 24 h and in the hippocampus after 48 h. These changes correlate well with histopathology. Diabetic rats have shown the effect of hyperglycemia in accentuation of ischemic and post ischemic pH changes. Conversely, diabetic rats maintained severely hypoglycemic with insulin showed little variation in pH during or following the ischemic insult. The results emphasize the importance of both MRS and MRI in following the temporal profile and distribution of ischemic neuronal injury.