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Biomedical subjects

N A Weerasena

Publications and source records attributed to N A Weerasena.

9 recordsLinked to original sources
PubMed2001

Effect of Trendelenburg head position during cardiac deairing on cerebral microemboli in children: a randomized controlled trial.

OBJECTIVES: We prospectively evaluated the effects of head position during cardiac deairing on the Doppler ultrasonography-detected cerebral microemboli in children and the association between the embolic counts and the clinical assessment of deairing. METHODS: Children requiring exposure of the systemic ventricle under cardiopulmonary bypass were randomized to Trendelenburg (-15 degrees ) and horizontal (0 degrees ) head positions during and after standard surgical deairing. Complexity of repair was categorized as follows: group I consisted of single simple lesions, and group II consisted of multiple complex lesions. Transcranial Doppler ultrasonography identified high-intensity transient signals in the right middle cerebral artery within the first 5 minutes after aortic declamping (release) and from this ending period until cardiopulmonary bypass termination (residual). Electrocardiographic alterations after deairing were documented. A predefined 5-point scale was used by the surgeon for blinded assessment of deairing. RESULTS: High-intensity transient signals were identified in 97% of 128 patients (aged 5 days to 17 years). The median total high-intensity transient signal count was 60 (25th-75th quartiles, 14-189). Head position or surgeon did not affect the rate of high-intensity transient signals (P >.20). During the residual interval, occurrence of HITS in group I was less than that in group II (P <.05), but there was no difference at release. The incidence of high-intensity transient signals and electrocardiographic alterations correlated with the clinical assessment of deairing (P <.01). CONCLUSIONS: Trendelenburg head position as a complement of cardiac deairing in children does not decrease the cerebral microembolic load compared with the horizontal head position. The cerebral microembolic count and the occurrence of electrocardiographic alterations usually increases when the surgeon is less confident in the efficacy of deairing.

Cardiac Surgical Procedures↗
PubMed2000

Cerebral vascular effects of aortovenous cannulations for pediatric cardiopulmonary bypass.

BACKGROUND: The effects of aortovenous cannulations for pediatric cardiopulmonary bypass on cerebral blood flow velocity (CBFV) and electroencephalography (EEG) were evaluated. METHODS: CBFV and EEG were continuously recorded before (baseline), during, and after cannulations until initiation of cooling (mean +/- 95% confidence interval). Vasopressors and/or volume replacement were administered if mean arterial pressure (MAP) decreased below 35 mm Hg. Cannulation-related EEG slowing was used as a criterion for electrocortical alteration. RESULTS: We studied 124 children (3 days to 17 years of age). Aortic and venous cannulations decreased mean CBFV by 10+/-3% and 13+/-4%, respectively, from baseline (p < 0.001). MAP diminished (p < 0.01) by 8+/-3% and 12+/-4%, respectively, from precannulation values (53+/-2 mm Hg). Right atrial cannulation, which was often chosen because the patient was hemodynamically unstable, was more frequently associated with pharmacologic intervention when compared with superior vena cava (SVC) cannulation (p < 0.01). Transient EEG alterations (n = 20) were associated with persistently low MAP (< 30 mm Hg), low CBFV (< 69%), and aortic (n = 4) or SVC (n = 7) cannula malposition. Infants with right atrial cannulation and intervention had more frequent EEG alterations (p = 0.04). Patients requiring intervention were younger (p < 0.01) and had longer hospital stay (p < 0.01) than those without intervention. CONCLUSIONS: Cerebral effects of cannulations are greater in young infants. This was found to be associated with low MAP during heart manipulation or consequence of cannula malpositions.

Adolescent↗
PubMed1997

Prospective, randomized, double-blind study of high-dose aprotinin in pediatric cardiac operations.

BACKGROUND: Perioperative aprotinin decreases postoperative blood loss in adults undergoing cardiac operations, but its role is less clear in children. Therefore, a trial of aprotinin in pediatric cardiac operations was conducted to study the efficacy of its use in children. METHODS: Forty-two patients were randomly assigned to receive either high-dose aprotinin or placebo. Aprotinin efficacy was assessed using time from protamine administration to skin closure, postoperative blood loss and hemoglobin loss, and postoperative transfusion requirements. Measures of fibrinolysis (fibrin degradation product titers) and platelet preservation (beta-thromboglobulin levels) were also assessed. RESULTS: There were no statistically significant differences between groups in any of the blood loss or transfusion parameters. Fibrin degradation product levels, measured 4 hours postoperatively, had increased significantly for control patients, but remained unchanged for the aprotinin group (p < 0.02). beta-Thromboglobulin levels increased more rapidly during cardiopulmonary bypass in the control group (p = 0.03). CONCLUSIONS: Aprotinin appears to provide no clinical benefit in routine pediatric cardiac operations. A reduction in fibrinolysis, with perhaps an early preservation of platelet structure, is seen in the aprotinin group.

Aprotinin↗
PubMed1997

Cerebral effects in superior vena caval cannula obstruction: the role of brain monitoring.

A pediatric cardiac case of transient obstruction of the superior vena cava by the venous cannula before cardiopulmonary bypass is presented. With venous obstruction and increase in central venous pressure, reduced cerebral blood flow velocities and absence of diastolic Doppler flow were detected. This was followed by regional cerebral venous oxygen desaturation and global electroencephalographic slowing. Reposition of the venous cannula led to the recovery of these physiologic indicators and a noncomplicated clinical outcome.

Catheterization↗
PubMed1992

Carbomedics and St. Jude Medical bileaflet valves: an in vitro and in vivo comparison.

The hydrodynamic and haemodynamic function of 29 mm mitral and 23 mm aortic St Jude Medical (SJM) and CarboMedics (CM) heart valves have been compared in a pulsatile flow simulator in the laboratory and by doppler ultrasound in vivo. The laboratory studies showed that there was no significant difference in the pressure drop across the valves. The valves also had similar regurgitant volumes. Doppler ultrasound confirmed these results with a mean pressure drop of 12.9 +/- 5.5 mmHg across the CM aortic valves and 12.6 +/- 5.5 mmHg for the SJM aortic valves. The mean mitral diastolic pressure drops were 3.8 +/- 1.8 and 4.6 +/- 1.4 mmHg for the CM and SJM valves, respectively. Mild aortic regurgitation was detected in 5 of 14 patients in the CM group and 1 out of 6 patients in the SJM group, though none of the cases were clinically significant. Both the in vitro and in vivo results show these valves to have acceptable and comparable function.

Aortic Valve↗
PubMed1990

A system for ambulatory monitoring and computerised analysis of oesophageal motility and luminal pH.

It is often desirable to monitor physiological events from subjects free to participate in their normal daily activities. This is especially so where clinical symptoms are elusive or precipitated by specific activities. Through ambulatory monitoring, evidence of a causal relationship between recorded parameters and the spontaneous onset of symptoms may be revealed. We describe an ambulatory monitoring system which permits continuous 24-hour recording of oesophageal motility from three levels within the oesophagus together with luminal pH. Computerised analysis of the recorded data addresses many of the problems associated with processing the information accrued through long-term monitoring by providing an automatic comparison of patient data against either preselected values or those of the program's algorithm. Motility is quantified in terms of wave frequency, amplitude, duration and temporal relationship together with an integration of the wave area and mean pressure baseline. The corresponding pH data is quantified as frequency, duration and integrated area of pH excursions throughout a range of pH1-8. This system provides access to the entire patient record which may either be viewed on screen, analysed or output to a printer. Analysis yields a tabulated breakdown of motility and pH events from any section of the patient's record. Selective analysis readily permits statistical comparison of discrete time-matched samples corresponding to different patient circumstances.

Algorithms↗
PubMed1989

Atrial myxoma as the cause of acute lower limb ischaemia in a teenager.

We report a case of a previously well teenager presenting with a sudden cardiovascular collapse due to a saddle embolus. This required immediate surgical intervention. Histology of the embolic material showed it was myxomatous. Echocardiography confirmed the diagnosis and the patient made an uneventful recovery following excision of the right arterial myxoma.

Adolescent↗