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Biomedical subjects

A G Fraser

Publications and source records attributed to A G Fraser.

At least 109 records · Page 6Linked to original sources
PubMed1990

The spectrum of systemic candidiasis at Auckland Hospital.

Systemic candidiasis is uncommon. We reviewed our experience with this disease from the infectious disease unit, Auckland Hospital, between 1982 and 1988, because many of these patients are referred to us. We then selected 11 of them to highlight particular presentations, diagnostic or management issues. We included both compromised and noncompromised patients from medical and surgical services. Candida albicans was the most common cause, but we also saw patients infected with C glabrata, C parapsilosis, and C tropicalis and present them to exemplify their different clinical presentations. Demonstrable fungaemia is uncommon in patients with systemic candidiasis, serological techniques are both insensitive and nonspecific and patients are often too ill from underlying disease to allow for invasive diagnostic procedures. Thus diagnosis is often difficult. Parenteral amphotericin B with or without 5-fluorocytosine is still the main antifungal treatment. Triazole antifungals may change that in the future. Systemic candidiasis retains a high mortality: careful individualised management of patients may improve mortality and morbidity.

Adult↗
PubMed1990

The potential value of transoesophageal evaluation of individual pulmonary venous flow after an atrial baffle procedure.

Following a Mustard's procedure, transoesophageal echocardiography allowed the visualization of all 4 pulmonary veins in 7/12 patients (mean age 14.8 years) and of three veins in a further 2 patients. Both upper pulmonary veins could be visualized consistently. No patient had an isolated pulmonary venous stenosis. In 9 patients in sinus rhythm, computer analysis of Doppler tracings from the left upper pulmonary vein showed significantly lower systolic peak velocities (mean 0.39 +/- 0.10 m/s) and time velocity integrals (mean 6.9 +/- 1.66 cm) than in normal subjects (mean 0.6 +/- 0.09 m/s and 14.4 +/- 2.97 cm respectively; P less than 0.001). We postulate that this is due to compromised atrial relaxation and compliance. In contrast, patients in junctional rhythm (mean 10.7 vs. 7.7 cm in normal subjects). Flow reversal during early ventricular systole (due to tricuspid regurgitation or atrial contraction after retrograde conduction during junctional rhythm) was detected in 6/12 patients. These results confirm that the transoesophageal approach should allow the identification of isolated pulmonary venous obstruction after a Mustard procedure. In addition. detailed analysis of tracings of flow in the pulmonary veins can document the presence of compromised atrial relaxation and help to evaluate the severity of tricuspid regurgitation. It may provide a new index with which to assess impaired systemic ventricular function.

Adolescent↗
PubMed1990

Assessment of ventricular septal defect closure by intraoperative epicardial ultrasound.

Intraoperative epicardial two-dimensional echocardiographic imaging, color flow mapping and contrast echocardiography were used in 31 patients after patch closure of a ventricular septal defect to determine their respective values in the assessment of residual shunting after cardiopulmonary bypass and for the prediction of long-term results. Epicardial imaging showed no incidence of patch dehiscence. Residual shunting detected by color flow mapping or contrast echocardiography was graded into one of four categories (0 to III). Real time analysis of color flow mapping studies suggested no shunting (grade 0) in 2 patients, grade I shunting in 20, grade II in 8 and grade III in 1; contrast studies suggested grade 0 in 15, grade I in 6, grade II in 8 and grade III in 2. Interobserver variation in real time encoding of grade I or II shunting was 25% by color flow mapping and 6% by contrast echocardiography. Subsequent frame by frame analysis revealed that both diastolic and early systolic right ventricular turbulence gave rise to false positive results during real time analysis of color flow mapping studies. Color flow mapping allowed exact localization of residual shunting, whereas contrast echocardiography allowed better semiquantification. Postbypass results were correlated in 30 patients with late postoperative precordial studies (mean interval 7.5 months). Persistent shunts were found in 6 (20%) of 30 patients. No patient required reoperation for residual shunting. The predictive value of immediate grade I or II shunting as a marker for persistent long-term shunting was poor, whereas both patients with immediate grade III shunting had shunt persistence, indicating that immediate revision should be considered in such patients. Intraoperative epicardial ultrasound is valuable for the immediate exclusion of important residual shunting after ventricular septal defect closure. Maximal information is obtained when color flow mapping and contrast echocardiography are used in combination.

Cardiopulmonary Bypass↗
PubMed1990

Acute haemodynamic effects of intravenous infusion of adenosine in conscious man.

The acute haemodynamic effects of intravenous infusion of adenosine, a dilator of most vascular beds, were studied in 16 patients (seven with coronary artery disease, nine with normal coronary arteries) undergoing cardiac catheterization for investigation of chest pain. At the lowest dose used (4.3 mg min-1) adenosine increased minute ventilation by 44% (P less than 0.01, n = 11) and reduced pulmonary vascular resistance by 20% (P less than 0.05) without causing other significant haemodynamic changes. Symptoms, including chest discomfort in 14 patients and dyspnoea in 11, limited the maximum dose to 8.5 +/- 2.3 mg min-1 (mean +/- SD, 108 +/- 24 micrograms kg-1 min-1). At this dose, adenosine reduced pulmonary and systemic vascular resistance (by 38% and 34%, respectively) and increased heart rate (by 34%), stroke index (by 12%) and cardiac index (by 52%). Systemic blood pressure and right atrial pressure did not change. Unexpectedly, adenosine increased left ventricular end-diastolic pressure (LVEDP) (from 5 +/- 6 to 14 +/- 10 mmHg, n = 8), pulmonary capillary wedge pressure (from 3 +/- 2 to 10 +/- 5 mmHg, n = 16) and consequently mean pulmonary artery pressure (from 10 +/- 2 to 16 +/- 5 mmHg). Minute ventilation increased by 84% (n = 11), resulting in hypocapnia (PCO2: 31 +/- 3 mmHg, n = 8) and alkalosis (pH: 7.46 +/- 0.02, n = 8). Oxygen consumption was unchanged during the infusion, but increased by 21% 5 min post infusion. All effects were similar in patients with and without coronary artery disease. Adenosine therefore causes pulmonary and systemic vasodilation and respiratory stimulation. Symptoms and an increase in LVEDP of uncertain cause, which occur with high doses, may limit the use of adenosine as a systemic vasodilator in conscious subjects. However at lower doses adenosine causes selective pulmonary vasodilation which merits further study.

Adenosine↗
PubMed1990

Transoesophageal echocardiography in the longitudinal axis: correlation between anatomy and images and its clinical implications.

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.

Aorta, Thoracic↗
PubMed1990

Do changes in pulmonary capillary wedge pressure adequately reflect myocardial ischemia during anesthesia? A correlative preoperative hemodynamic, electrocardiographic, and transesophageal echocardiographic study.

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)

Anesthesia, Inhalation↗
PubMed1990

Adverse hemodynamic effects and echocardiographic consequences of pericardial closure soon after sternotomy and pericardiotomy.

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.

Animals↗
PubMed1989

Endoscopic palliation of malignant obstructive jaundice.

Patients referred for endoscopic retrograde cholangiopancreatography (ERCP) over a 12 month period who had a diagnosis of malignant obstructive jaundice prior to or confirmed by the procedure were reviewed. Insertion of a biliary endoprosthesis was attempted in 23 out of 26 patients and was successful in 19 (82%). A significant fall in bilirubin was seen in 15 (79%) of those who had a successful procedure. The only early complication was cholangitis in two patients. Late complications were related to occlusion of the endoprosthesis and replacement was required in six patients. Endoscopic palliation of malignant obstructive jaundice is a useful technique and should be considered as the initial procedure in all patients considered to have nonresectable malignancy.

Adult↗
PubMed1989

Colour flow mapping in cardiology: indications and limitations.

Colour flow mapping (CFM) produces a two-dimensional representation of blood flow within the heart and great vessels by analysing data acquired from multiple pulsed Doppler sample volumes, and displaying mean velocity and turbulence of flow at each site. Constraints imposed by the time required to process these data mean that CFM cannot be used for precise velocity measurements. Instead it depicts flow patterns in healthy and abnormal hearts and the precise location and direction of turbulent jets. CFM is an integral part of the standard echocardiographic examination; it is especially useful in neonates and children with congenital heart disease, and in adults for the semi-quantitative assessment of valve regurgitation, and the description of flow patterns in complex acquired disease. Transoesophageal echocardiography with CFM is invaluable for the diagnosis of mitral prosthetic valve dysfunction, aortic dissection, and complications of infective endocarditis. Intraoperative epicardial CFM provides the equivalent of intraoperative angiography.

Blood Flow Velocity↗
PubMed1989

Effects of enalapril on myocardial noradrenaline overflow during exercise in patients with chronic heart failure.

The effects of the angiotensin converting enzyme inhibitor enalapril on myocardial sympathetic tone, as represented by noradrenaline overflow, were studied in 14 men with congestive heart failure (mean ejection fraction 20%) in a double blind crossover comparison with placebo. Arterial and coronary sinus catecholamine concentrations and oxygen content, and coronary sinus blood flow, were measured at rest and during peak symptom limited upright exercise on a bicycle ergometer. There were no significant changes four hours after the first dose of enalapril, but after six weeks of treatment (10-20 mg/day) enalapril reduced myocardial overflow of noradrenaline at peak exercise. The external workload (exercise duration) increased from baseline values after both placebo and enalapril, and there was no difference between placebo and enalapril at six weeks. Heart work, however, was lower after enalapril: stroke work index was reduced at rest and the double product was lower at peak exercise. The reduction in maximal myocardial oxygen consumption after enalapril did not reach statistical significance. Coronary sinus adrenaline concentrations after enalapril and after placebo were not significantly different. The long term reduction of myocardial sympathetic activity on exercise may represent a significant benefit from angiotensin converting enzyme inhibition in heart failure and may reflect a reduced cardiac workload.

Adult↗
PubMed1989

Unusual and intraoperative epicardial echocardiographic features of a papillary tumour of the aortic valve.

A mass with a diameter of 0.8 cm was detected in the aortic root of a 53 year old woman during routine preoperative cross sectional echocardiographic assessment of a secundum atrial septal defect. Intraoperative epicardial echocardiography showed that the mass was attached by a slender stalk to the tip of the left coronary cusp of the aortic valve, and histological examination showed that it was a papillary tumour. Intraoperative epicardial echocardiography can help in planning the excision of papillary tumours, and excision is advised even when there are no symptoms.

Aortic Valve↗
PubMed1989

Extensive aortic valve ring abscess formation: a rare complication of Q fever endocarditis.

We report the successful management and 2 year follow up of a young patient with Q fever endocarditis on a congenitally bicuspid aortic valve complicated by extensive abscess formation in the aortic valve ring and interventricular septum. Aortic root abscess formation complicating Q fever endocarditis has been reported in only one previous patient. Serological tests may thus be indicated in patients with aortic abscesses. Despite extensive aortic and intramyocardial abscess formation it proved possible to control the progression of disease by open drainage of the abscess and aortic valve replacement. Although the requirement for aortic root replacement was anticipated in this patient, it has not been required.

Abscess↗
PubMed1988

A randomized cross-over study of enalapril in congestive heart failure: haemodynamic and hormonal effects during rest and exercise.

We performed a randomized double-blind placebo controlled cross-over study of enalapril in 16 patients with chronic congestive heart failure, to assess haemodynamic and hormonal effects at rest and on exercise. Acute effects were measured 4 h after enalapril 10 mg, and chronic effects after 6 weeks treatment with enalapril 10-20 mg per day. Exercise tolerance, assessed by the duration of a maximal bicycle ergometer test, was not altered by enalapril. Mean blood pressure was reduced after enalapril, at rest and on exercise, acutely by 7% and 8% respectively, and chronically by 14% and 16%. Systemic vascular resistance was reduced by 16% at rest both acutely (NS) and chronically (p less than 0.05). The resting pulmonary capillary wedge pressure was reduced by 28% with chronic treatment. In the acute study, total body oxygen consumption on exercise was 26% higher after enalapril. Chronically, resting oxygen consumption was reduced by 13% after enalapril, with mixed venous oxygen saturation increasing by 16%. In the acute study enalapril increased plasma renin activity at rest and on exercise by 181% and by 189%, and reduced aldosterone by 49% (NS) and 39% (p less than 0.05), and these effects were sustained after 6 weeks. Enalapril increased antidiuretic hormone concentrations at rest acutely by 73% (NS) and chronically by 34% (p less than 0.05) but not on exercise; the increase in the acute study correlated with plasma enalaprilat levels (r = 0.66, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

A possible drug interaction between rifampicin and enalapril.

When a 35-year-old man with essential hypertension was treated with antibiotics for brucellosis his blood pressure rose significantly. While all other treatment was kept constant rifampicin was discontinued. On rechallenge rifampicin did not alter serum concentrations of enalapril or the area under the curve (AUC) between 0 and 7 h, but it did reduce the AUC of the active metabolite enalaprilat by 31%. These observations suggest that there may be an interaction between rifampicin and enalapril, causing reduced hypotensive efficacy of enalapril. The mechanism of such an interaction merits further study, but it could be due to enhanced renal clearance of enalaprilat.

Adult↗