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Biomedical subjects

S M Bradley

Publications and source records attributed to S M Bradley.

At least 19 recordsLinked to original sources
PubMed2003

Sinus node dysfunction after intraatrial lateral tunnel and extracardiac conduit fontan procedures.

This study compares the effects of two techniques for the Fontan procedure-intraatrial lateral tunnel (IALT) and extracardiac conduit (ECC) -on sinus node dysfunction. Between January 1992 and December 1998, 54 patients underwent a total cavopulmonary connection Fontan procedure. Of these, 36 had follow-up 24-hour Holter recordings, and they constitute the population for this study. The 24-hour Holter recordings were performed between January 1998 and March 1999 and were evaluated for sinus node dysfunction and atrial tachycardia. Clinical follow-up (18 +/- 11 months for the IALT group vs 34 +/- 19 months for the ECC group; p = 0.002) and surface electrocardiograms were also reviewed. Among the 36 patients, 19 had an IALT and 17 had an ECC Fontan procedure. The incidence of sinus node dysfunction was 4/19 (21%) in the IALT group and 10/17 (59%) in the ECC group (p = 0.04). No patient from either group had an identified episode of atrial tachycardia. No permanent pacemaker was placed in the IALT group, whereas three were placed in the ECC group, all for sinus node dysfunction. In summary, patients with both IALT and ECC had an important incidence of sinus node dysfunction. The incidence of sinus node dysfunction was higher in the ECC group, which may have been due to longer follow-up in this group. Atrial tachycardia was not observed in either group. Although the IALT group had less sinus node dysfunction than the ECC group and appeared to require less permanent pacing, these data may be too limited to serve as the criteria for choosing between these two techniques for performing the Fontan procedure.

Bradycardia↗
PubMed2001

Aortopulmonary collateral flow in the Fontan patient: does it matter?

BACKGROUND: The effects of aortopulmonary collaterals (APCs) on the outcome of a Fontan procedure are unclear. We undertook this study to define the incidence and extent of APC flow, identify risk factors for APC flow, and determine if APC flow has a measurable effect on the outcome of a Fontan procedure. METHODS: The APC flow was directly measured in 32 patients undergoing Fontan procedures from July 1997 to September 2000. The APC flow was measured in the operating room during total cardiopulmonary bypass, and was expressed as a percentage of total bypass pump flow. RESULTS: The APC flow ranged from 9% to 49% of total pump flow (median, 18%). Higher preoperative systemic oxygen saturation, pulmonary artery oxygen saturation, pulmonary to systemic flow ratio, and angiographic APC grade correlated with higher APC flow. There were no operative deaths; there was one Fontan takedown (APC flow = 14%). The APC flow had no significant effects on postoperative Fontan pressure, common atrial pressure, transpulmonary gradient, duration of effusions, or resource utilization after the Fontan procedures. CONCLUSIONS: In patients undergoing a Fontan procedure, APC flow is omnipresent, although its extent varies widely. Increased APC flow has no significant effect on the outcome of a Fontan procedure. This conclusion applies to patients who are well prepared for a Fontan procedure, but may not extend to patients at higher risk.

Aortography↗
PubMed2001

Hemodynamic effects of inspired carbon dioxide after the Norwood procedure.

BACKGROUND: Mortality in the early postoperative period after the Norwood procedure remains substantial. Inspired carbon dioxide (CO2) has been suggested to improve hemodynamic status in this setting. Inspired CO2 can be delivered by one of two strategies, ie, with or without an accompanying increase in minute ventilation. The hemodynamic effects of these two strategies have not previously been studied in a controlled fashion. METHODS: Seventeen infants (median age, 9 days; range, 4 to 49 days) undergoing Norwood procedures were prospectively enrolled in this crossover study. Patients were studied while sedated, paralyzed, and mechanically ventilated 1 day to 6 days after operation. The inspired oxygen fraction was kept constant (mean value, 0.24 +/- 0.01). Measurements were made at five time points: 1 = baseline; 2 = inspired CO2 with increased ventilation; 3 = baseline; 4 = inspired CO2 alone; and 5 = baseline. Mixed venous oxygen saturation was monitored using indwelling lines in the superior vena cava. RESULTS: Inspired CO2 with increased ventilation produced a rise in mean airway pressure with no change in arterial CO2 tension or pH. This strategy had no effect on hemodynamic status or oxygen delivery. Inspired CO2 alone produced a rise in arterial CO2 tension and a fall in arterial pH (respiratory acidosis). This strategy resulted in significant improvement in both variables of systemic oxygen delivery: mixed venous oxygen saturation increased from 48% +/- 2% to 56% +/- 2% (p < 0.05), and arteriovenous oxygen saturation difference decreased from 3% +/- 2% to 26% +/- 2% (p < 0.05). CONCLUSIONS: Inspired CO2 after the Norwood procedure can improve oxygen delivery. This improvement occurs only if minute ventilation is kept constant. There is no improvement if minute ventilation is increased. Clinical use of inspired CO2 may be limited by the accompanying fall in pH. Differentiation of cerebral from total-body effects of inspired CO2 will require further study.

Administration, Inhalation↗
PubMed2000

Considerations in biventricular repair after the Norwood procedure.

OBJECTIVE: The Norwood procedure can be applicable as a first stage palliation in children who can eventually undergo a biventricular repair. Although usual management of these patients is a primary neonatal repair, in selected patients staged approach with a Norwood procedure in the neonatal period followed by a Rastelli procedure in the infancy for conversion to two-ventricle physiology has been used alternatively. METHODS: We report our experiences on two infants who underwent a previous palliation with the Norwood procedure for lesions other than hypoplastic left heart syndrome and converted to two-ventricle physiology by the use of a Rastelli-type procedure. This report examines considerations in biventricular repair after the Norwood procedure especially need for ventricular septal defect enlargement and approach to placement of the right ventricle to pulmonary artery conduit. RESULTS: Both of the infants who underwent staged approach with an initial Norwood procedure for lesions other than hypoplastic left heart syndrome survived the operations and were clinically well at mid-term follow-up. CONCLUSION: In selected patients, the staged approach is an alternative in management of malformations other than hypoplastic left heart syndrome which share the important physiologic features of aortic outlet obstruction and ductal dependency of systemic circulation. We recommend routine enlargement of ventricular septal defect and proper positioning of the conduit at the time of subsequent biventricular repair.

Abnormalities, Multiple↗
PubMed2000

Reliability of intraoperative transesophageal echocardiography during Tetralogy of Fallot repair.

UNLABELLED: There is limited information available concerning the accuracy of intraoperative transesophageal echocardiography (TEE) in predicting the extent of residual abnormalities after recovery from surgical repair of tetralogy of Fallot. Therefore, we investigated differences between the results of final postbypass TEE and those of postrecovery (mean, 6 days after surgery) transthoracic echocardiography in a total of 28 consecutive pediatric patients who underwent repair of tetralogy of Fallot with biplane or multiplane TEE. Both postbypass and postrecovery echocardiographic examinations included measurements of the right ventricle (RV)-main pulmonary artery (PA) and the main PA-branch PA peak instantaneous gradients, the degree of pulmonary valvar insufficiency, and color Doppler interrogation of the ventricular septum for residual defects. The RV-main PA gradient did not change significantly: 15 +/- 13 vs 18 +/- 14 mmHg (postbypass versus postrecovery, mean +/- SD). None of the patients had a decrease of > or = 10 mmHg; and only one patient had an increase of > or = 15 mmHg. There also was no change in the degree of pulmonary insufficiency (3.0 +/- 1.2 versus 3.1 +/- 1.1, using a scale of 0 to 4). Only one of the seven very small (< or = 2 mm) residual ventricular septal defects was not discovered during postbypass TEE. However, postrecovery transthoracic echocardiography detected significant branch PA stenosis (peak gradient, > or = 15 mmHg) in five patients (18%) that was not detected during postbypass TEE (P < 0.03). Of the branch PA stenoses that were not detected during TEE, four were left and one was right. CONCLUSIONS: Postbypass TEE after tetralogy of Fallot repair reliably predicts residual postrecovery hemodynamic abnormalities, except for branch PA stenosis.

Adolescent↗
PubMed1999

Long-term experience with the St. Jude Medical valve prosthesis.

BACKGROUND: All patients undergoing St. Jude Medical valve replacement at the Medical University of South Carolina since January 1979 have been followed prospectively at 12-month intervals. METHODS: This report describes long-term experience in 710 adult patients undergoing isolated aortic (AVR) (418) or mitral valve replacements (MVR) (292) with this prosthesis from January 1979 to December 1996. RESULTS: Ages ranged from 19 to 84 years (54.8 +/- 15.1 AVR, 51.8 +/- 12.9 MVR; mean +/- SD). Male gender predominated in the AVR group (70%) and female gender in the MVR group (62%). One hundred and fifty-seven patients (22%) had associated coronary artery bypass grafting (AVR 27%, MVR 15%). Thirty-day operative mortality was 5.3% (22/418) in the AVR group and 5.1% (15/292) in the MVR group. Follow-up is 96.9% complete and ranges from 1 month to 16.9 years (AVR, 2,376 patient-years, mean 5.7 +/- 4.5 years; MVR, 1,868 patient-years, mean 6.4 +/- 4.8 years). In the AVR group, 120 late deaths have occurred and actuarial survival was 78.0 +/- 2.3%, 58.0 +/- 3.2%, and 36.8 +/- 4.8%; at 5, 10, and 15 years, respectively. Forty-six patients have sustained 55 thromboembolic (TE) events (2.3%/patient-year). Fifty-one patients had anticoagulant-related bleeding complications (2.7%/patient-year). The mean improvement in New York Heart Association (NYHA) functional class from preoperative to postoperative was 3.0 +/- 0.8 to 1.7 +/- 0.1 (p < 0.05). In the MVR group, there have been 84 late deaths, and the actuarial survival was 79.3 +/- 2.5%, 60.1 +/- 3.5%, and 49.3 +/- 4.1% at 5, 10, and 15 years, respectively. Fifty-two patients have had 64 TE events (3.5%/patient-year). Twenty-three patients had anticoagulant-related bleeding complications (1.6%/patient-year). The mean improvement in NYHA functional class was from 3.3 +/- 0.6 to 1.8 +/- 0.1. There were no mechanical failures in either group. CONCLUSIONS: With a follow-up now extending to 17 years, the St. Jude Medical valve continues to be a reliable mechanical prosthesis with low and stable rates of valve-related complications.

Actuarial Analysis↗
PubMed1999

Current concepts in heart valve surgery.

After a period of relatively regimented approaches for mitral and aortic valve surgery, recent years have seen numerous innovations including improved prostheses, improved techniques for repair, better understanding of the physiology of ventricular function and myocardial protection, advances in anticoagulation control, and most recently the application of minimally invasive techniques. Each of these has contributed to the improved short and long term results obtained from valve surgery, and further evolution of these techniques will undoubtedly improve the results even more. As operative risks are decreased and long term results are improved, it is hoped that patients with valvular heart disease will be referred at progressively earlier stages of their disease for consideration for surgery. Earlier referral increases the likelihood that valve repair will be possible in the case of the mitral valve and also increases the odds that the outcome from valve surgery will be successful for both aortic and mitral valves.

Adult↗
PubMed1998

Hyperventilation impairs oxygenation after bidirectional superior cavopulmonary connection.

BACKGROUND: Bidirectional superior cavopulmonary connection (BSCC) may be complicated by systemic hypoxemia. Hyperventilation, which is standard therapy for postoperative hypoxemia, has opposing effects on the pulmonary and cerebral vascular beds, which are connected after BSCC. It is unknown which of these effects predominates and, therefore, whether hyperventilation improves or impairs systemic oxygenation after BSCC. METHODS AND RESULTS: Twelve consecutive patients (median age, 6.4 months; age range, 6.0 to 32.0, months) undergoing BSCC were studied prospectively. Patients were studied in the intensive care unit within 6 hours of surgery and while sedated, paralyzed, and mechanically ventilated. Inotropes were not altered, and no transfusions were given. FIO2 was set at 100%, and peak end-expiratory pressure was set at 0. Each patient was studied first during normal ventilation, then during hyperventilation, and finally again during normal ventilation. Hyperventilation resulted in significant decreases in arterial PO2, systemic oxygen saturation, and transpulmonary gradient. Cerebral blood flow velocity was measured in 6 patients through transcranial Doppler sonography of the middle cerebral artery. Mean cerebral flow velocity decreased significantly during hyperventilation. CONCLUSIONS: Hyperventilation significantly impairs systemic oxygenation after BSCC. This fall in oxygenation occurs despite a decrease in transpulmonary gradient. A possible mechanism for this effect is that hyperventilation lowers arterial PCO2, raising cerebral vascular resistance, and lowering cerebral, superior vena caval, and pulmonary blood flows. Supportive evidence for this mechanism is the decrease in cerebral flow velocity that occurs during hyperventilation. After BSCC, normal ventilation rather than hyperventilation should be used to improve systemic oxygen levels.

Adolescent↗
PubMed1997

Anticoagulation in children with mechanical valve prostheses.

BACKGROUND: Clotting complications in patients with mechanical valve prostheses can be prevented with either warfarin sodium (Coumadin; DuPont, Wilmington, DE) or antiplatelet agents. In children, it is not known whether one treatment regimen is more effective or safe than the other. METHODS: We prospectively followed up 64 children and young adults (aged 18 years or younger at implantation) with a mechanical valve on the left side of the heart, from October 1986 through October 1996. Forty-eight patients were treated with Coumadin and 16 with aspirin and dipyridamole. The two groups were similar in age, sex, valve location and size, mean length of follow-up, and operative indication. There has been a total follow-up of 272 patient-years on Coumadin and 116 patient-years on aspirin and dipyridamole. RESULTS: There was no difference between the two groups in survival or freedom from thromboembolism. Bleeding occurred more often in the patients taking Coumadin, but this difference was not statistically significant. Analysis of the literature showed thromboembolism and bleeding rates to be similar in the patients receiving Coumadin and those receiving antiplatelet agents. CONCLUSIONS: Coumadin and the combination of aspirin plus dipyridamole provided similar protection against complications in this group of children and young adults with left-sided St. Jude (St. Paul, MN) mechanical valves. The choice between the two regimens may depend on other factors, such as patient preference and convenience.

Adolescent↗
PubMed1997

The effect of sulphasalazine on neutrophil superoxide generation in rheumatoid arthritis.

The production of superoxide by the peripheral blood neutrophils of 19 patients with active rheumatoid arthritis was measured during treatment with sulphasalazine (SASP). The response to drug treatment was determined by change in plasma viscosity, CRP, early morning stiffness and articular index over a 10-point scale. Of the 19 patients studied, eight were considered to have responded well to SASP and seven to have responded poorly or not at all. Over the treatment period, plateau levels of superoxide production fell in seven of the eight responders (P = 0.028) compared with a non-significant fall in 3/7 of the non-responder groups. The initial rate of superoxide production also fell in the responder group, but this was not statistically significant. Initial values in both the responder and non-responder groups were comparable with those seen for normal controls. Analysis of drug levels showed all patients to be compliant with drug treatment; however, drug levels and neutrophil activity were not correlated. Studies of the effect of SASP and sulphapyridine on superoxide production in vitro showed no difference between good and poor responders. These results suggest that there is no inherent difference between good and poor responders regarding the susceptibility of their neutrophils to SASP. SASP's action on neutrophils, therefore, appears not to be its main mechanism of disease-modifying activity in RA.

Antirheumatic Agents↗
PubMed1996

Bidirectional superior cavopulmonary connection in young infants.

BACKGROUND: Bidirectional superior cavopulmonary connection (BSCC) has become widely used in patients with univentricular AV connections. However, concerns remain about perioperative morbidity and mortality and about the adequacy of oxygenation after cavopulmonary connection in very young patients. This report examines our experience with BSCC in young infants to evaluate whether young age affects operative outcome, to examine the effect of young age on postoperative oxygenation, and to define the lower age limit for successful use of the procedure. METHODS AND RESULTS: The records of the 85 consecutive patients < 6.5 months old who underwent BSCC from December 1990 through February 1995 were reviewed. The average patient age was 4.8 +/- 1.4 months (range, 5 weeks to 6.5 months), with 13 patients being < 3 months old. There were 5 hospital deaths (6%; 70% confidence limits, 3% to 10%). Pulmonary artery thrombosis occurred in 3 patients (4%; 70% confidence limits, 2% to 7%). Younger age was significantly associated with pulmonary artery thrombosis but not with operative death. Oxygenation (arterial PO2, and oxygen saturation) improved significantly and spontaneously over the first 48 hours after BSCC. Younger age had a significant adverse effect on oxygenation in the early postoperative period (first 48 hours). CONCLUSIONS: BSCC can be performed successfully in infants < 6 months old and as young as 5 weeks old. Within this patient population, younger age is not associated with perioperative death but is associated with pulmonary artery thrombosis and postoperative hypoxemia. We suggest that BSCC may be performed any time beyond the neonatal period in symptomatic patients and may be delayed until 4 to 6 months of age if completely elective.

Female↗
PubMed1993

71Ga and 31P MAS NMR spectroscopic studies of cloverite.

71Ga and 31P MAS NMR studies have been undertaken of the gallophosphate molecular sieve, cloverite. Two 71Ga resonances were observed of the as-synthesized cloverite (ambient humidity) at 92 and -24 ppm. The first of these is assigned to five coordinate and the second to six coordinate gallium, where in both cases there is one fluoride ion in the first gallium coordination sphere. Dehydration of the sample decreased the intensity of the six coordinate signal relative to that of the five coordinate one, whereas hydrating had the reverse effect, suggesting that the upfield signal is due to six coordinate gallium sites generated through the adsorption of water. The 31P MAS NMR spectrum of a dehydrated sample revealed one weak resonance at -0.8 ppm as well as strong signals at -9.7 and -11.2 ppm. The -0.8 ppm resonance is attributed to the T5 [P(OGa)3OH] sites whereas the strong signals are assigned to the T1-T4 sites [P(OGa)4]. Upon humidifying, several new resonances appear between 0 and -6 ppm which have been assigned to phosphorus atoms having nearest neighbour gallium atoms in varying degrees of hydration.

Gallium↗
PubMed1993

Cervical cytology screening: a comparison of uptake among 'Asian' and 'non-Asian' women in Oldham.

This study investigates the response of 'Asian' and 'non-Asian' women to a computer-generated invitation to attend for a cervical smear during a one-year period. One hundred and fifty-eight 'Asian' women were compared with 158 non-'Asian' women from four general practices in Oldham; the women were aged between 50 and 64 years and were from a restricted geographical area to control for socioeconomic factors. It was found that there was no difference in the response to the test invitation between the two groups (uptake in 'Asians' 61.5 per cent, 'non-Asians' 60.6 per cent). 'Non-Asian' women were more likely to have had a previous smear than 'Asian' women. The Family Health Services Authority register contained a higher number of inaccurate addresses for 'Asian' women. It is suggested that ethnicity did not seem to play an important part in the uptake of cervical smear testing in this population.

Asia↗