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Biomedical subjects

P M Schofield

Publications and source records attributed to P M Schofield.

At least 37 records · Page 2Linked to original sources
PubMed1998

Coronary angiography from the radial artery--experience, complications and limitations.

AIMS: to assess the outcomes, complications and limitations of coronary angiography performed via percutaneous radial artery puncture. METHODS AND RESULTS: two hundred and fifty patients underwent diagnostic coronary angiography from the radial artery, 182 (72.8%) of whom had contraindications to the femoral approach, for example due to peripheral vascular disease (n=85), therapeutic anticoagulation (29), or failed femoral approach (17). Procedural success in this high-risk population was achieved in 231 patients (92.4%). Principle reasons for failure were unsuccessful radial access (5) and arterial spasm (5). Procedure duration (SD) for an operator's first 20 cases compared with cases thereafter (min) was 47.7 (16.7) vs. 41.5 (14.6), P=0.0004; fluoroscopy time (min) 9.7 (7.1) vs. 6.6 (5.1), P=0.0001 and procedural success 89.6% vs. 94.1%, P=ns. Complications included two deaths associated temporally with catheterisation, three cases of arterial dissection without ischaemic sequelae and one transient ischaemic attack. CONCLUSIONS: coronary angiography can be performed successfully from the radial artery, but this approach has limitations, which include the need to demonstrate dual palmar vascular supply, the prolonged learning phase, the procedural failure rate, patient discomfort and a demonstrable incidence of vascular and haemodynamic complications. We believe that radial coronary angiography should only be undertaken when there is a contraindication to the femoral approach.

Chi-Square Distribution↗
PubMed1998

Comparison of radial versus brachial approaches for diagnostic coronary angiography when the femoral approach is contraindicated.

One hundred patients with contraindications to the femoral approach were randomized to undergo diagnostic coronary angiography via percutaneous radial puncture or brachial artery cutdown. Procedure duration, fluoroscopy time, and total radiation dose were significantly less via the radial route, whereas procedural success, complication rates, and pain scores were comparable; we conclude that the radial technique should be the arm approach of choice for new trainees, although there will be occasions when radial access fails and a brachial approach is required.

Aged↗
PubMed1998

Ventricular pacemaker upgrade: experience, complications and recommendations.

OBJECTIVE: To assess outcomes of pacemaker upgrade from single chamber ventricular to dual chamber. DESIGN: Retrospective analysis of patients undergoing the procedure. SETTING: Specialist cardiothoracic unit. PATIENTS: 44 patients (15 female, 29 male), mean (SD) age at upgrade 68.2 (12.9) years. INTERVENTIONS: Upgrade of single chamber ventricular to dual chamber pacemaker. MAIN OUTCOME MEASURES: Procedure duration and complications. RESULTS: Principal indications for upgrade were pacemaker syndrome (17), "opportunistic"--that is, at elective generator replacement (8), heart failure (7), non-specific breathlessness/fatigue (7), and neurally mediated syncope (3). Mean (SD) upgrade procedure duration (82.9 (32.6) minutes) significantly exceeded mean VVI implantation duration (42.9 (13.3) minutes) and mean DDD implantation duration (56.6 (22.7) minutes) (both p < 0.01). Complications included pneumothorax (1), ventricular arrhythmia requiring cardioversion (2), protracted procedure (10), atrial lead repositioning within six weeks (8), haematoma evacuation (1), superficial infection (1), and admission to hospital with chest pain (1); 20 patients (45%) suffered one or more complications including four of the eight who underwent opportunistic upgrade. CONCLUSIONS: Pacemaker upgrade takes longer and has a higher complication rate than either single or dual chamber pacemaker implantation. This suggests that the procedure should be performed by an experienced operator, and should be undertaken only if a firm indication exists. Patients with atrial activity should not be offered single chamber ventricular systems in the belief that the unit can be upgraded later if necessary at minimal risk.

Aged↗
PubMed1998

Late complications following permanent pacemaker implantation or elective unit replacement.

OBJECTIVE: To determine the rate of late complications following first implantation or elective unit replacement of a permanent pacemaker system. DESIGN: Analysis of pacemaker data and complications prospectively acquired on a computerised database. Complications were studied over an 11 year period from January 1984 to December 1994. SETTING: Tertiary referral cardiothoracic centre. PATIENTS: Records of 2621 patients were analysed retrospectively. MAIN OUTCOME MEASURES: Complications requiring repeat procedures occurring more than six weeks after pacemaker implantation or elective unit replacement. RESULTS: The overall rate of late complications was significantly lower after first implantation of a permanent pacemaker (34 cases, complication rate 1.4%, 95% confidence interval 0.9% to 1.9%) than after elective unit replacement (16 cases, complication rate 6.5% (3.3% to 9.7%). There were 20 cases of erosion, 18 infections, five electrode problems, and seven miscellaneous problems. Complications were more common with inexperienced operators (18.9% (6.0% to 31.8%)) than with experienced operators (0.9% (0.3% to 1.5%). CONCLUSIONS: The incidence of late complications following pacemaker implantation is low and compares favourably with early complication rates. The majority are caused by erosion and infection. Patients who have undergone elective unit replacement are at particular risk.

Adult↗
PubMed1997

Both endothelium-dependent and endothelium-independent function is impaired in patients with angina pectoris and normal coronary angiograms.

BACKGROUND: The aim of this study was to investigate both endothelium-dependent and endothelium-independent vasodilatation in syndrome X patients. Recently selective impairment of endothelium-dependent function has been reported in a small number of syndrome X patients. However, other investigators have reported impaired endothelium-independent function. METHODS: We infused the endothelium-independent vasodilators papaverine and glyceryl trinitrate, and endothelium-dependent vasodilator acetylcholine in the left coronary artery of 35 patients with syndrome X and in 17 control subjects (atypical chest pain, negative exercise test, and normal coronary angiograms). Coronary blood flow was measured with an intracoronary Doppler catheter positioned in the proximal left anterior descending coronary artery, and the artery diameter was assessed using quantitative coronary angiography. RESULTS: The mean increase in coronary blood flow in response to a 12 mg dose of papaverine was significantly less in the syndrome X group (185 +/- 74% vs 411 +/- 59%, P < 0.001). The increase in coronary blood flow in response to acetylcholine, at doses of 1, 3, 10, and 30 micrograms.min-1, was also significantly lower in the syndrome X group (12 +/- 13 (P < 0.05), 41 +/- 33, 57 +/- 68, and 124 +/- 87% (P < 0.001)) as compared to the control group (76 +/- 49, 214 +/- 116, 355 +/- 115, and 361 +/- 74%). CONCLUSION: These findings demonstrate that both endothelium-dependent and endothelium-independent dilatation of the coronary microvasculature is impaired in syndrome X.

Acetylcholine↗
PubMed1996

Randomised controlled trial of vitamin E in patients with coronary disease: Cambridge Heart Antioxidant Study (CHAOS)

BACKGROUND: Vitamin E (alpha-tocopherol) is thought to have a role in prevention of atherosclerosis, through inhibition of oxidation of low-density lipoprotein. Some epidemiological studies have shown an association between high dietary intake or high serum concentrations of alpha-tocopherol and lower rates of ischaemic heart disease. We tested the hypothesis that treatment with a high dose of alpha-tocopherol would reduce subsequent risk of myocardial infarction (MI) and cardiovascular death in patients with established ischaemic heart disease. METHODS: In this double-blind, placebo-controlled study with stratified randomisation, 2002 patients with angiographically proven coronary atherosclerosis were enrolled and followed up for a median of 510 days (range 3-981). 1035 patients were assigned alpha-tocopherol (capsules containing 800 IU daily for first 546 patients; 400 IU daily for remainder); 967 received identical placebo capsules. The primary endpoints were a combination of cardiovascular death and non-fatal MI as well as non-fatal MI alone. FINDINGS: Plasma alpha-tocopherol concentrations (measured in subsets of patients) rose in the actively treated group (from baseline mean 34.2 micromol/L to 51.1 micromol/L with 400 IU daily and 64.5 micromol/L with 800 IU daily) but did not change in the placebo group. Alpha-tocopherol treatment significantly reduced the risk of the primary trial endpoint of cardiovascular death and non-fatal MI (41 vs 64 events; relative risk 0.53 [95% Cl 0.34-0.83; p=0.005). The beneficial effects on this composite endpoint were due to a significant reduction in the risk of non-fatal MI (14 vs 41; 0.23 [0.11-0.47]; p=0.005); however, there was a non-significant excess of cardiovascular deaths in the alpha-tocopherol group (27 vs 23; 1.18 [0.62-2.27]; p=0.61). All-cause mortality was 36 of 1035 alpha-tocopherol-treated patients and 27 of 967 placebo recipients. INTERPRETATION: We conclude that in patients with angiographically proven symptomatic coronary atherosclerosis, alpha-tocopherol treatment substantially reduces the rate of non-fatal MI, with beneficial effects apparent after 1 year of treatment. The effect of alpha-tocopherol treatment on cardiovascular deaths requires further study.

Coronary Artery Disease↗
PubMed1996

Cardioesophageal reflex: a mechanism for "linked angina" in patients with angiographically proven coronary artery disease.

OBJECTIVES: The purpose of this study was to investigate the presence of a cardioesophageal reflex in patients with coronary artery disease that may explain the mechanism of "linked angina." BACKGROUND: It has been previously shown that esophageal acid stimulation can reduce coronary blood flow in patients with syndrome X, suggesting the presence of a cardioesophageal reflex in humans. METHODS: We studied the effect of esophageal acid stimulation on coronary blood flow in 14 patients with angiographically documented significant coronary artery disease and in 18 heart transplant recipients. Hydrochloric acid (0.1 mol/liter) and 0.9% saline solution were infused in random, double-blind manner (60 ml over 5 min) through a fine-bore tube positioned in the patient's distal esophagus, and coronary blood flow measurements were obtained after each infusion by use of a 3.6F intracoronary Doppler catheter positioned in the proximal left anterior descending coronary artery. RESULTS: Coronary blood flow was reduced significantly by esophageal acid stimulation in the coronary artery disease group (before acid 70.4 +/- 14.3 ml/min, after acid stimulation 46.4 +/- 19.1 ml/min [mean +/- SD], p < 0.01). However, there was no significant difference in coronary blood flow during saline infusion (73.5 +/- 15.3 vs. 72.5 +/- 14 ml/min). Coronary blood flow in the heart transplant group was not affected by acid or saline infusion. CONCLUSIONS: Esophageal acid stimulation can cause animal attacks and significantly reduce coronary blood flow in patients with coronary artery disease. The lack of any significant effect in heart transplant recipients with heart denervation suggests a neural reflex.

Aged↗
PubMed1996

Aging-associated endothelial dysfunction in humans is reversed by L-arginine.

OBJECTIVES: This study investigated the hypothesis that aging selectively impairs endothelium-dependent function, which may be reversible by administration of L-arginine. BACKGROUND: An impaired response to acetylcholine with aging has been demonstrated in humans. However, the mechanisms underlying this impaired response of the coronary microvasculature remain to be determined. METHODS: We infused the endothelium-independent vasodilators papaverine and glyceryl trinitrate (GTN) and the endothelium-dependent vasodilator acetylcholine (1,3,10 and 30 micrograms/min) into the left coronary artery of 34 patients (27 to 73 years old) with atypical chest pain, negative exercise test results, completely normal findings on coronary angiography and no coronary risk factors. Coronary blood flow was measured with an intracoronary Doppler catheter. The papaverine and acetylcholine infusions were repeated in 14 patients (27 to 73 years old) after an intracoronary infusion of L-arginine (160 mumol/min for 20 min). RESULTS: There was a significant negative correlation between aging and the peak coronary blood flow response evoked by acetylcholine (r = -0.73, p < 0.0001). However, there was no correlation to papaverine (r = -0.04, p = 0.82) and GTN (r = -0.24, p = 0.17). The peak coronary blood flow response evoked by acetylcholine correlated significantly with aging before L-arginine infusion (r = -0.87, p < 0.0001), but this negative correlation was lost after L-arginine infusion (r = -0.37, p = 0.19). CONCLUSIONS: The results suggest that aging selectively impairs endothelium-dependent coronary microvascular function and that this impairment can be restored by administration of L-arginine, a precursor of nitric oxide.

Acetylcholine↗
PubMed1996

Excellent outcome of cardiac transplantation using domino donor hearts.

OBJECTIVE: Domino cardiac transplantation affords flexible and optimal organ utilization, provides hearts unaffected by brain death, allows prospective tissue matching, and subsequent transplantation with short allograft ischemic times. A retrospective review of our experience with domino cardiac transplantation has been made. METHODS: Seventy-two of 119 patients who underwent heart-lung transplantation from 1988 on served as domino cardiac donors (40 males, 32 females; mean age of 32 years; mean weight of 51 kg). The domino donor diagnoses were cystic fibrosis (n = 47), bronchiectasis (n = 9), primary pulmonary hypertension (n = 6), emphysema (n = 7), pulmonary fibrosis (n = 2) and Eisenmenger's syndrome (n = 1). Forty-seven domino hearts were transplanted at our institution and 25 were exported to other centres in the United Kingdom. The 72 domino cardiac recipients were 62 males and 10 females, mean age of 47 years, mean weight of 60 kg, with ischemic heart disease (n = 32), cardiomyopathy (n = 36) and other conditions (n = 4). RESULTS: There were four deaths (5.6%) at less than 30 days (2 from multiple organ failure, 1 from primary allograft failure and 1 from acute rejection). Actuarial survival estimates and 1 and 5 years were 77 +/- 5.2% nd 69 +/- 6.3%, respectively. This compared favourably with survival data obtained in 234 non-domino cardiac recipients. In the patients transplanted at Papworth, there was no difference in the incidence of rejection (0.6 +/- 0.05 versus 0.7 +/- 0.03 events per 100 patient days for the first 12 months) or in the freedom from graft atherosclerosis (74 +/- 3% versus 70 +/- 3% at 5 years) between the domino and non-domino groups. CONCLUSIONS: The use of domino hearts donated by recipients of heart-lung transplants is beneficial and is associated with an excellent early and longer-term outcome.

Actuarial Analysis↗
PubMed1996

Cardio-oesophageal reflex in humans as a mechanism for "linked angina'.

The aim of this study was to investigate the hypothesis that oesophageal acid stimulation reduces coronary blood flow in humans as a result of the presence of a cardio-oesophageal reflex which may provide a mechanism for "linked angina'. We studied the effect of oesophageal acid stimulation on coronary blood flow in 35 syndrome X patients and 24 heart transplant patients. A fine tube was positioned into the patient's distal oesophagus. An intracoronary Doppler catheter was positioned in the proximal left anterior descending coronary artery for coronary blood flow measurements. Oesophageal instillation of 0.1 M hydrochloric acid was performed (60 ml over 5 min) and the measurements were repeated. The coronary blood flow was significantly reduced by acid oesophageal stimulation in the syndrome X group [pre-acid 78.9 +/- 36.4 ml. min-1, post-acid 50.8 +/- 32.9 ml.min-1 (P = 0.0001)]. However, coronary blood flow in the heart transplant group, in whom the heart is denervated, was unaffected by acid infusion. We conclude that oesophageal acid stimulation can produce angina and significantly reduce coronary blood flow in humans. The lack of any significant effect in the heart transplant group, in whom the heart is denervated, suggests a neural reflex.

Adult↗
PubMed1996

Permanent pacing in a patient with a left ventricular assist system.

A patient with end stage heart failure underwent permanent implantation of a Novacor left ventricular assist system. Progressive right ventricular dysfunction developed during the first two postoperative weeks. Temporary and subsequently permanent atrioventricular pacing to correct first degree heart block improved the performance of the device, with sustained resolution of his right ventricular failure.

Cardiac Pacing, Artificial↗
PubMed1996

Changing from intensive anticoagulation to treatment with aspirin alone for coronary stents: the experience of one centre in the United Kingdom.

OBJECTIVE: To investigate whether an elective change in the anticoagulation protocol for patients with coronary stents affected clinical outcomes and length of hospital stay. DESIGN: Retrospective observational study of a consecutive series of patients treated with coronary stents over an 18 month period from April 1994 to October 1995. BACKGROUND: Intensive anticoagulation regimens are used in many UK centres to reduce the risk of coronary stent thrombosis. Recent data have called into question the necessity for full anticoagulation and favourable results have been reported with antiplatelet agents alone. The results from a tertiary referral centre were investigated during a period where an elective change in policy was made: an initial 70 patients were treated intensively with intravenous heparin and with warfarin and aspirin; subsequently 94 were treated with aspirin and deployment of a high pressure balloon only. METHODS: Review of case notes, angiograms, and a database of intervention procedures and telephone interview. Classic epidemiological techniques, as well as linear regression and logistic regression, were used to model the outcomes of major procedural complications and length of hospital stay. PATIENTS: 164 patients treated with 196 coronary stents. RESULTS: There were 22 (13.4%) major complications (coronary bypass grafting 11, subacute thrombosis 6, tamponade 2, myocardial infarction 1, death 2). With logistic regression, the risk of major complication was shown not to be affected by anticoagulation (relative risk (RR) 1.03; P = 0.97). Significant determinants of risk included acute vessel closure as an indication for stenting (RR = 80.6; P < 0.001) and sex (male: female RR = 0.19; P = 0.02). The median length of stay (LOS) was 5 days (1-45). Use of a linear regression model showed that anticoagulation added 4.5 days and a major complication added a further 4.5 days to a baseline length of stay of 3.2 days (R2 = 0.32; P < 0.001). CONCLUSION: This is a report of coronary stenting as part of usual clinical practice in one British tertiary referral centre. In this experience, treatment with aspirin alone is probably as safe as intensive anticoagulation, and has the benefit of reducing length of stay by more than 50% to 3.2 days in an uncomplicated case.

Anticoagulants↗
PubMed1996

Coronary flow reserve and oesophageal dysfunction in syndrome X.

The relative prevalence of abnormalities of coronary flow reserve and oesophageal function was ascertained in 32 syndrome X patients with typical angina chest pain, a positive exercise test, and normal coronary arteries. Coronary flow reserve in response to a hyperaemic dose of papaverine was measured using an intracoronary Doppler catheter positioned in the left anterior descending coronary artery. An abnormal coronary flow reserve was defined as being < 3.0. Patients were investigated for oesophageal dysfunction by manometry and 24-hour pH monitoring. Thirteen patients had an impaired coronary flow reserve (group 1) and 19 patients had a normal flow reserve (group 2). Eight of the 13 group 1 patients (62%) and 13 of the 19 group 2 patients (68%, p = NS) had evidence of oesophageal dysfunction on either manometry or pH studies. Therefore, a total of 26 (81%) syndrome X patients had either an abnormality of coronary flow reserve or oesophageal dysfunction suggesting that chest pain in these patients may be due to myocardial ischaemia or oesophageal dysfunction, thus confirming the heterogeneous nature of this syndrome. The prevalence of oesophageal abnormalities was independent of any abnormalities of coronary flow reserve.

Adult↗
PubMed1995

The serum concentration of active transforming growth factor-beta is severely depressed in advanced atherosclerosis.

Recent evidence has led us to propose that transforming growth factor-beta (TGF-beta) is a key inhibitor of atherosclerosis. We show here that a population of patients with advanced atherosclerosis all have less active TGF-beta in their sera than patients with normal coronary arteries, with a fivefold difference in average concentration between the two groups. This correlation with atherosclerosis is much stronger than for other known major risk factors and it may therefore have important diagnostic and prognostic significance. Aspirin medication correlates with an increase in active TGF-beta concentration, indicating that therapeutic interventions for TGF-beta are possible.

Aged↗