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Biomedical subjects

P Bloomfield

Publications and source records attributed to P Bloomfield.

At least 19 recordsLinked to original sources
PubMed1994

Mechanism of closed chest cardiopulmonary resuscitation investigated by transoesophageal echocardiography.

Transoesophageal echocardiography (TOE) was performed during closed chest cardiopulmonary resuscitation (CPR) in 18 subjects in cardiac arrest. Compression of all four cardiac chambers resulted in forward flow in the pulmonary and systemic circulations, retrograde pulmonary vein flow and incomplete mitral valve closure. Antegrade pulmonary vein flow and left ventricular filling occurred exclusively during the relaxation phase. These findings support the cardiac pump theory of CPR and are incompatible with the thoracic pump mechanism. TOE merits further investigation as a device to monitor and guide resuscitation efforts during CPR.

Adult↗
PubMed1994

Cardiac parasympathetic activity in severe uncomplicated coronary artery disease.

BACKGROUND: Previous studies have suggested that coronary artery disease is independently associated with reduced cardiac parasympathetic activity, and that this is important in its pathophysiology. These studies included many patients with complications that might be responsible for the reported autonomic abnormalities. OBJECTIVE: To measure cardiac parasympathetic activity in patients with uncomplicated coronary artery disease. PATIENTS AND METHODS: 44 patients of mean (SD) age 56 (8) with severe uncomplicated coronary artery disease (symptoms uncontrolled on maximal medical treatment; > 70% coronary stenosis at angiography; normal ejection fraction; no evidence of previous infarction, diabetes, or hypertension). Heart rate variability was measured from 24 hour ambulatory electrocardiograms by counting the number of times successive RR intervals exceeded the preceding RR interval by > 50 ms, a previously validated sensitive and specific index of cardiac parasympathetic activity. RESULTS: Mean (range) of counts were: waking 112 (range 6-501)/h, sleeping 198 (0-812)/h, and total 3912 (151-14 454)/24 h. These mean results were unremarkable, and < 10% of patients fell below the lower 95% confidence interval for waking, sleeping, or total 24 hour counts in normal people. There was no relation between the severity of coronary artery disease or the use of concurrent antianginal drug treatment and cardiac parasympathetic activity. CONCLUSION: In contrast with previous reports no evidence of a specific independent association between coronary artery disease and reduced cardiac parasympathetic activity was found. The results of previous studies may reflect the inclusion of patients with complications and not the direct effect of coronary artery disease itself.

Adrenergic beta-Antagonists↗
PubMed1993

Retention of bioprosthetic valve annulus in mitral prosthetic replacement.

Mitral valve prosthetic replacement carries high mortality rates by modern standards, and mitral bioprostheses are particularly prone to degeneration. Bioprosthetic replacement may be technically difficult when there is calcification of the tissue ingrowth, strut incorporation, or valve-to-annulus size mismatch at the primary operation. A "valve-in-valve" technique is described where the mechanical prosthesis is implanted in the bioprosthetic annulus in order to avoid such difficulties. The results in the first eight patients are presented, showing post-operative Doppler-derived transvalvar mean gradients between 3.9 mmHg and 7.5 mmHg, and estimated valve areas between 1.9 cm2 and 3.5 cm2. All patients are alive at between 20 and 30 months (mean 23.6 months) after operation, they are without serious post-operative morbidity and are in functional class I or II (NYHA classification).

Aged↗
PubMed1993

Additional value of biplane transoesophageal imaging in assessment of mitral valve prostheses.

OBJECTIVES: To determine whether biplane transoesophageal imaging offers advantages in the evaluation of mitral prostheses when compared with standard single transverse plane imaging or the precordial approach in suspected prosthetic dysfunction. DESIGN: Prospective mitral valve prosthesis in situ using precordial and biplane transoesophageal ultrasonography. SETTING: Tertiary cardiac referral centre. SUBJECTS: 67 consecutive patients with suspected dysfunction of a mitral valve prosthesis (16 had bioprostheses and 51 mechanical prostheses) who underwent precordial, transverse plane, and biplane transoesophageal echocardiography. Correlative invasive confirmation from surgery or angiography, or both, was available in 44 patients. MAIN OUTCOME MEASURES: Number, type, and site of leak according to the three means of scanning. RESULTS: Transverse plane transoesophageal imaging alone identified all 31 medial/lateral paravalvar leaks but only 24/30 of the anterior/posterior leaks. Combining the information from both imaging planes confirmed that biplane scanning identified all paravalvar leaks. Five of the six patients with prosthetic valve endocarditis, all three with valvar thrombus or obstruction, and all three with mitral annulus rupture were diagnosed from transverse plane imaging alone. Longitudinal plane imaging alone enabled diagnosis of the remaining case of prosthetic endocarditis and a further case of subvalvar pannus formation. CONCLUSIONS: Transverse plane transoesophageal imaging was superior to the longitudinal imaging in identifying medial and lateral lesions around the sewing ring of a mitral valve prosthesis. Longitudinal plane imaging was superior in identifying anterior and posterior lesions. Biplane imaging is therefore an important development in the study of mitral prosthesis function.

Adult↗
PubMed1992

Atrial myxoma: tumour or trauma?

A mass lesion developed in the right atrium at the site of a trans-septal puncture after percutaneous balloon dilatation of the mitral valve in a man aged 74. The lesion had the pathological appearance of an atrial myxoma and seemed to have developed after trauma to the intra-atrial septum. This case suggests that at least some atrial myxomas are reactive rather than neoplastic in origin.

Aged↗
PubMed1991

In vivo distribution of opioid receptors in man in relation to the cortical projections of the medial and lateral pain systems measured with positron emission tomography.

In vivo opioid receptor binding in the cortical projections of the medial (cingulate and prefrontal cortex) and lateral pain system (primary somatosensory cortex) in male volunteers has been quantitated using [11C]diprenorphine and positron emission tomography. High levels of opioid receptor binding were seen in the cortical projections of the medial pain system in the cingulate and prefrontal cortex as has previously been observed in post-mortem studies. However, a focal reduction of opioid receptor binding was observed and quantitated in the primary motor/sensory strip when compared to surrounding parietal cortex. This new finding suggests that the medial pain system is likely to be more susceptible to exogenous and endogenous opioid neuromodulation than the so-called lateral pain system.

Adult↗
PubMed1991

Twelve-year comparison of a Bjork-Shiley mechanical heart valve with porcine bioprostheses.

BACKGROUND: Patients undergoing heart-valve replacement may receive a mechanical prosthesis, necessitating lifelong anticoagulant treatment, or a porcine bioprosthesis, which involves no absolute need for anticoagulants. METHODS: We carried out a randomized, prospective trial to compare the durability of the Bjork-Shiley mechanical prosthesis (spherical tilting-disk model) and the incidence of valve-related complications with those variables in the Hancock and the Carpentier-Edwards porcine prostheses. The mitral valve was replaced in 261 patients, the aortic valve in 211, and both in 61; the survivors have been followed up for a mean of 12 years. RESULTS: We found a trend toward improved actuarial survival after 12 years with the Bjork-Shiley prosthesis, but this trend was not statistically significant (group with Bjork-Shiley valve vs. group with porcine valve [mean +/- SE], 51.5 +/- 3.2 vs. 44.4 +/- 3.2 percent; P = 0.08). There was no significant difference in the actuarial incidence of reoperation after 5 years, but after 12 years significantly more patients with a porcine prosthesis had undergone reoperation (8.5 +/- 2.0 vs. 37.1 +/- 4.1 percent, P less than 0.001). An analysis combining death and reoperation as end points for an actuarial assessment of survival with the original prosthesis intact confirmed that the patients with Bjork-Shiley Shiley prostheses had improved survival (48.6 +/- 3.2 vs. 30.0 +/- 3.0 percent after 12 years, P less than 0.001). Bleeding requiring hospitalization or blood transfusion was significantly more frequent in the patients with Bjork-Shiley prostheses (18.6 +/- 3.2 vs. 7.1 +/- 2.3 percent after 12 years, P less than 0.01). There was no significant difference after 12 years in the actuarial occurrence of embolism (Bjork-Shiley vs. porcine, 21.1 +/- 3.1 vs. 26.4 +/- 3.5 percent) or endocarditis (3.7 +/- 1.4 vs 4.6 +/- 1.6 percent). CONCLUSIONS: Survival with an intact valve is better among patients with the Bjork-Shiley spherical tilting-disk prosthesis than among patients with porcine bioprostheses, but use of the Bjork-Shiley valve carries an attendant increased risk of bleeding associated with the need for anticoagulant treatment.

Actuarial Analysis↗
PubMed1990

Patients' observations of bioprosthetic valve failure: "my heart is honking, doctor".

Audible cardiac murmurs are uncommon and may indicate severe native valve dysfunction. In six patients with bioprosthetic mitral valves audible honking systolic murmurs suddenly developed. Doppler echocardiography showed characteristic striated regurgitant signals. At operation each prosthesis had torn cusps. New audible murmurs and striated Doppler signals originating from mitral bioprosthetic valves are indicators of cusp tears. Recognition of this is important because early detection of prosthetic valve dysfunction may improve subsequent surgical outcome.

Aged↗
PubMed1990

Perioperative myocardial infarction after coronary artery bypass surgery. Clinical significance and approach to risk stratification.

The clinical significance of perioperative myocardial infarction (MI) after coronary artery bypass surgery is not known. Therefore, strategies for the risk stratification of these patients do not exist. This study was undertaken to define the effect of perioperative MI on prognosis after discharge from the hospital and to develop an approach to the risk stratification of these patients. Fifty-nine patients with and 115 patients without perioperative MI were observed for 30 months for the development of cardiac events (death, nonfatal MI, and admission to hospital for unstable angina or congestive heart failure). Patients with perioperative MI were significantly more likely than patients without to have a cardiac event (31% versus 12%, p less than 0.01) and multiple events (19% versus 1%, p less than 0.001). Cox regression analysis identified two independent predictors of cardiac events other than perioperative MI (relative risk, 2.7): inadequate revascularization (relative risk, 3.5) and depressed (less than 40%) postoperative ejection fraction (EF) (relative risk, 2.1). Event-free survival rate of patients with perioperative MI varied markedly depending on the number of other negative prognostic variables present. Patients with perioperative MI who were adequately revascularized and had a postoperative EF greater than 40% had an event-free survival rate similar to patients without a perioperative MI (92% versus 87%, p = NS). Patients with perioperative MI who were inadequately revascularized and had depressed postoperative EF had an event-free survival rate of 13% (p less than 0.001 versus all other subsets). Event-free survival rate was intermediate (68%) in patients with perioperative MI and with only one of the other two variables (p less than 0.001 versus other subsets). In conclusion, perioperative MI adversely affects prognosis. Patients can be stratified into low, high, and intermediate risk subsets based on a simple assessment of the adequacy of revascularization and a determination of residual left ventricular function.

Coronary Artery Bypass↗
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↗