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Biomedical subjects

P Bloomfield

Publications and source records attributed to P Bloomfield.

At least 55 records · Page 3Linked to original sources
PubMed1989

Anaesthetic management of the patient with a permanent pacemaker.

Over 25,000 people in Britain now have pacemakers, and the number is increasing steadily. Anaesthetists encounter patients with pacemakers regularly. Knowledge about the increasingly wide range of pacemakers available is necessary to ensure safe management of these patients, many of whom are frail and elderly. This review outlines the indications for permanent pacing, the types of pacemaker used and the assessment and management of pacemaker patients for anaesthesia.

Anesthesia↗
PubMed1989

Long-term follow-up of patients with the QT rate adaptive pacemaker.

We report a 5-year follow-up of eight patients implanted with the QT sensing rate adaptive pacemaker, the Vitatron TX. Careful programming was undertaken shortly after implantation utilizing repeated exercise testing to ensure optimal settings. Further exercise testing was not carried out during follow-up as the patients remained symptomatically well. Of six patients assessed with repeat exercise testing at 5 years, four demonstrated a satisfactory rate adaptive response with improved exercise performance compared to fixed rate ventricular pacing, one patient had an abrupt onset of increased pacing rate with exercise associated with improved exercise ability, and another developed an increased pacing rate after exercise but an appropriate rate adaptive response after reprogramming. One patient developed an inappropriately high pacing rate associated with congestive heart failure several months after a large myocardial infarction. One patient died from carcinoma. The QT sensing rate adaptive pacemaker appears to be reliable in lon-term clinical use when carefully programmed using exercise testing after implantation.

Aged↗
PubMed1989

Acute toxicity of ropivacaine compared with that of bupivacaine.

The acute central nervous and cardiovascular effects of the local anesthetics ropivacaine and bupivacaine were compared in 12 volunteers in a randomized double-blind manner with use of intravenous infusions at a rate of 10 mg/min up to a maximal dose of 150 mg. The volunteers were all healthy men. They were familiarized with the central nervous system (CNS) toxic effects of local anesthetics by receiving a preliminary intravenous injection of lidocaine. The infusions of ropivacaine and bupivacaine were given not less than 7 days apart. CNS toxicity was identified by the CNS symptoms and the volunteers were told to request that the infusion be stopped when they felt definite but not severe symptoms of toxicity such as numbness of the mouth, lightheadedness, and tinnitus. In the absence of definite symptoms, the infusion was stopped after 150 mg had been given. Cardiovascular system (CVS) changes in conductivity and myocardial contractility were monitored using an interpretive electrocardiograph (which measured PR interval, QRS duration, and QT interval corrected for heart rate) and echocardiography (which measured left ventricular dimensions from which stroke volume and ejection fraction were calculated). Ropivacaine caused less CNS symptoms and was at least 25% less toxic than bupivacaine in regard to the dose tolerated. Both drugs increased heart rate and arterial pressure. Stroke volume and ejection fraction were reduced. There was no change in cardiac output. Although both drugs caused evidence of depression of conductivity and contractility, these appeared at lower dosage and lower plasma concentrations with bupivacaine than with ropivacaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

After the infarct.

Explore the source record for details and available documents.

Exercise Test↗
PubMed1987

A statistical test for synergism of two cell growth inhibitors.

Interaction of 2 inhibitors of cell growth can be detected by measuring the inhibiting effect of the 2 drugs separately and in combination. A control group is used as the basis for each comparison. We discuss a method for the statistical analysis of such measurements, when the basic observation is the number of cells harvested from a treated culture.

Cell Line↗
PubMed1987

Permanent pacing.

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Arrhythmias, Cardiac↗
PubMed1987

Ventricular septal defect after myocardial infarction: assessment by cross sectional echocardiography with pulsed wave Doppler scanning.

Eight patients who developed a ventricular septal defect after myocardial infarction were assessed by cross sectional echocardiography and pulsed wave Doppler scanning. Cross sectional echocardiography visualised the defect in four patients and gave an accurate assessment of global and regional left ventricular function in all eight. In all patients pulsed wave Doppler scanning detected turbulent flow at the apex of the right ventricle or adjacent to a wall motion abnormality affecting the interventricular septum. Pulsed wave Doppler detected coexisting mitral regurgitation in one patient and tricuspid regurgitation in another two. In all patients a left to right shunt was confirmed by oximetry and the location of the defect was identified by angiography or at operation or necropsy. Cross sectional echocardiography in combination with pulsed wave Doppler scanning is useful in the rapid bedside evaluation of patients with ventricular septal defect after myocardial infarction.

Aged↗
PubMed1986

A prospective evaluation of the Björk-Shiley, Hancock, and Carpentier-Edwards heart valve prostheses.

From 1975 to 1979, 540 patients undergoing valve replacement were entered into a randomized trial and received either a Björk-Shiley (273 patients) or a porcine heterograft prosthesis (initially a Hancock valve [107 patients] and later a Carpentier-Edwards prosthesis [160 patients]). Two hundred and sixty-two patients required mitral valve replacement, 210 required aortic valve replacement, 60 required mitral and aortic valve replacement, and eight also required associated tricuspid valve replacement (six mitral valve replacement; two mitral plus aortic valve replacement). Analysis of 34 preoperative and operative variables showed the treatment groups to be well randomized. In-hospital mortality was not significantly different among patients receiving the three prostheses for aortic valve replacement (7.6% overall) and mitral plus aortic valve replacement (10% overall), but there was a higher in-hospital mortality for patients undergoing mitral valve replacement with the Carpentier-Edwards prosthesis (15.5% compared with 8.8% overall; p = .03). This difference could not be explained on the basis of any preoperative or operative variable. Median follow-up was 5.6 (range 2.8 to 8.3) years. Actuarial survival after mitral valve replacement was 56.7 +/- 7.0% at 7 years, that after aortic valve replacement was 69.6 +/- 9.6% at 7 years, and that after mitral plus aortic valve replacement was 62.5 +/- 20.0% at 7 years. There was no significant difference in actuarial survival of patients receiving the three prostheses within the mitral, aortic, and mitral plus aortic valve replacement groups, nor was there a difference when these groups were amalgamated. Thirty-seven patients required reoperation for valve failure (15 with Björk-Shiley, 12 with Hancock, and 10 with Carpentier-Edwards valves; p = NS) and 11 died at reoperation (four with Björk-Shiley, four with Hancock, and three with Carpentier-Edwards valves; overall operative mortality 29.7%). Up to 7 years after surgery, there was no significant difference in the incidence of thromboembolism in patients with different prostheses undergoing mitral or aortic valve replacement. There were too few patients undergoing mitral plus aortic valve replacement for meaningful comparison. There was no significant beneficial effect of anticoagulants in patients undergoing mitral or aortic valve replacement with porcine prostheses, but patients were not randomly allocated to anticoagulant treatment. All patients with Björk-Shiley prostheses received anticoagulants.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1985

Non-Q wave perioperative myocardial infarction: assessment of the incidence and severity of regional dysfunction with quantitative two-dimensional echocardiography.

Since the widespread use of hypothermic potassium cardioplegia began, marked reductions in perioperative mortality and the rate of Q wave-associated myocardial infarctions have been noted. No study to date has evaluated whether there has been an equally dramatic improvement in the incidence of postoperative myocardial infarctions unassociated with Q wave development. We used a previously validated quantitative two-dimensional echocardiographic analytic algorithm to determine the incidence and severity of regional wall motion abnormalities (RWMAs) and first-pass radionuclide ventriculography to assess deterioration in global left ventricular function in the four following groups of patients (total n = 65): (1) those with peak postoperative creatine kinase (CK)-MB levels equal to or less than the mean value for patients undergoing coronary artery bypass surgery at our institution (n = 10), (2) those with CK-MB levels between the mean and 1 SD above the mean (n = 10), (3) those with peak CK-MB levels higher than 1 SD above the mean (n = 25), and (4) those with new pathologic Q waves on the postoperative electrocardiogram (n = 20). All patients had electrocardiograms without pathologic Q waves and normal wall motion and ejection fraction by contrast ventriculography before surgery. The incidence of postoperative RWMA by two-dimensional echocardiography for groups 1 through 4 was 0%, 20%, 55%, and 89%, respectively. Percent of abnormal left ventricular segments, wall motion scores, and the deterioration in left ventricular ejection fraction as assessed by radionuclide ventriculography were similar for patients with new RWMAs whether or not new Q waves developed (p = NS for all).(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1984

Brachial artery catheterization employing a side arm sheath.

A major complication of left heart catheterization via the brachial artery is occlusion at the cutdown site. This is particularly a problem when patients with severe atherosclerosis are catheterized in laboratories where the brachial approach is not routinely used. A method of brachial artery catheterization is described which employs a continuously flushed side arm sheath in order to minimize local trauma to the artery from catheter exchange and manipulation. In 15 consecutive atherosclerotic patients catheterized by this method there were no complications, and all arteriotomies were closed easily with immediate restoration of a good radial pulse. This contrasts with the preceding 33 consecutive brachial catheterizations employing standard technique in similar patients in whom four patients required surgical repair, and an additional six patients required more than one closure attempt and/or catheter thrombectomy to restore a good pulse. In our laboratory the brachial sheath technique has facilitated arterial repair and reduced local complications.

Arteriosclerosis↗
PubMed1984

Quantitative two-dimensional echocardiographic analysis of regional wall motion in patients with perioperative myocardial infarction.

Regional left ventricular wall motion was evaluated by two-dimensional echocardiographic techniques with fixed- and floating-axis analytical algorithms in three groups of subjects: normal subjects (n = 15), patients undergoing uncomplicated coronary artery bypass graft surgery (CABG) (n = 10), and patients suffering perioperative myocardial infarction (n = 27). In patients undergoing uncomplicated CABG, fixed-axis analysis in the apical four-chamber view produced septal hypokinesis indistinguishable from the septal hypokinesis seen in patients with anterior myocardial infarction. In addition, fixed-axis analysis enhanced lateral wall motion so that patients with lateral myocardial infarction were classified as normal. Floating-axis analysis corrected these limitations by (1) producing regional left ventricular wall motion in the patients undergoing uncomplicated CABG, which was identical to that in normal subjects, and (2) producing regional left ventricular wall motion in patients with myocardial infarction that was hypokinetic in segments corresponding to the electrocardiographic area of involvement. In patients with new Q waves, fixed-axis analysis detected abnormalities of regional left ventricular wall motion in 24 of 34 (71%) electrocardiographically involved regions but also classified 44 of 100 segments in uncomplicated patients as abnormal. Floating-axis analysis detected regional left ventricular wall motion abnormalities in 30 of 34 patients (88%; p less than .05 vs fixed-axis analysis) and only 15 of 100 segments in patients undergoing uncomplicated CABG were classified as abnormal (p less than .001 vs fixed-axis analysis). We conclude that floating-axis analysis is a more accurate and clinically relevant method of evaluating regional left ventricular wall motion in patients undergoing CABG who suffer myocardial infarction as a perioperative complication.

Coronary Artery Bypass↗