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Biomedical subjects

P M Schofield

Publications and source records attributed to P M Schofield.

At least 55 records · Page 3Linked to original sources
PubMed1994

Abnormal cardiac pain perception in syndrome X.

OBJECTIVES: The purpose of this study was to determine whether a diminished cardiac pain threshold contributes to chest pain in patients with syndrome X. BACKGROUND: There have been some reports of an altered pain perception in syndrome X. METHODS: Intracardiac catheter manipulation was performed in four groups of patients (syndrome X [group 1, 36 patients]; mitral valve disease and normal coronary arteries [group 2, 36 patients]; mitral valve disease and coronary artery disease [group 3, 36 patients]; and heart transplant recipients with normal coronary arteries [group 4, 36 patients]). Coronary flow velocity was measured in patients with syndrome X and in transplant recipients by use of an intracoronary Doppler catheter positioned in the left anterior descending coronary artery at intracardiac catheter manipulation. Coronary flow reserve in response to papaverine was also measured in patients with syndrome X and in transplant recipients. RESULTS: Intracardiac stimulation produced typical anginal chest pain in 34 group 1 (syndrome X) patients (94%). However, chest pain was produced only in five patients (14%) in group 2, seven patients (19%) in group 3 and no patients in group 4. There were no significant changes in coronary blood flow velocity associated with chest pain in group 1 patients. Coronary flow reserve in response to a hyperemic dose of intracoronary papaverine was significantly lower in the syndrome X group. There was no significant difference in the prevalence with which the stimulation tests produced chest pain in patients with syndrome X with an impaired coronary flow reserve or a positive radionuclide scan. CONCLUSIONS: The results of our study suggest that abnormal cardiac pain perception is a fundamental abnormality in syndrome X.

Adult↗
PubMed1994

Hyperinsulinemia, coronary artery disease and syndrome X.

OBJECTIVES: This study was conducted to compare the insulin responses to an oral glucose load in healthy volunteers and patients with syndrome X and patients with coronary artery disease. BACKGROUND: An abnormal coronary flow reserve has been reported in syndrome X by several investigators. However, its cause is not known. Recently, it has been suggested that elevated insulin levels in syndrome X may contribute to microvascular dysfunction. METHODS: Insulin responses to an oral glucose load (75 g) were compared in 17 patients with coronary artery disease, 17 patients with chest pain, positive exercise test findings, normal coronary arteries and impaired coronary flow reserve (syndrome X) and 17 healthy volunteers (control subjects). All were matched for age, gender and body weight. Patients with overt diabetes mellitus or hypertension were excluded. Venous blood samples were taken during fasting and at 30, 60, 90 and 120 min after the glucose load. Samples were analyzed for glucose, immunoreactive insulin and C peptides. RESULTS: There was no significant difference in the glucose levels at all sampling points among the three groups. The C peptide and immunoreactive insulin levels were significantly higher than values in the control group at 60, 90 and 120 min in the groups with syndrome X and coronary artery disease. The peak responses and the areas under the curve were also significantly greater in the latter two groups. There was no significant difference at all sampling points between the group with syndrome X and the group with coronary artery disease. CONCLUSION: Patients with syndrome X have stimulated hyperinsulinemia, which may contribute to the pathophysiology of syndrome X.

Blood Flow Velocity↗
PubMed1994

Early complications after dual chamber versus single chamber pacemaker implantation.

This study was performed to compare the frequency of early complications after single chamber versus dual chamber permanent pacemaker implantation. Early complication was defined as one occurring in the 6-week period following implantation. We prospectively analyzed consecutive pacemaker implantation from January 1987 to June 1993 at our regional center. All complications were also analyzed for the relationship to operator experience, the venous access route, and the presence of temporary pacing wire at the time of implantation of the permanent pacing system. A total of 2019 new pacemaker units were implanted during this period. 1733 patients (85.8%) received a VVI pacemaker and 286 (14.2%) a DDD unit. Wound infection occurred in 11 (0.6%) VVI patients and 6 (2.1%) DDD patients. Lead displacement occurred in 18 (1%) VVI patients and 15 (5.2%) DDD patients (11 [3.8%] atrial and 4 [1.4%] ventricular). There were 10 (0.6%) pneumothoraces, 9 (0.5%) hematomas requiring drainage, 1 (0.06%) chylocele, and 2 (0.1%) deaths in the VVI group. There were 2 (0.7%) pneumothoraces, 2 (0.7%) hematomas, and no deaths in the DDD group. There was no significant increase in complications for experienced infrequent implanters (< 12 systems per year). In both groups the subclavian approach was associated with a risk of pneumothorax when compared to the cephalic approach. The rate of wound infection was higher in patients who had a temporary pacing wire in place. The use of prophylactic antibiotics does not appear to affect the incidence of wound infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1994

Maze 3 for atrial fibrillation: two cuts too few?

The Maze procedure has been developed as a surgical approach to the management of patients with atrial fibrillation refractory to medical treatment. The recent modification of the technique (Maze 3) achieves good rate control with coordinated AV contractions. However, the procedure involves cuts that completely isolate a block of left atrial (LA) wall, including the four ostia of the pulmonary veins. The electrical and mechanical activity of this isolated LA block are dissociated from the rest of the atrium, and the area may, in fact, continue to fibrillate. This may provide a nidus for the development of mural thrombus. The weight and endocardial surface area of the LA block and of the entire LA were estimated in ten formalin fixed hearts from trauma victims with no evidence of cardiac disease. In these samples, the LA block represented 35% of the endocardial surface area of the entire LA and 29% of the weight. The LA block is of sufficient size to allow macroreentrant circuits to form and has the potential to fibrillate if isolated from the rest of the atrium. We modified the Maze 3 procedure to recruit the otherwise isolated LA block by using two additional cuts around each pair of pulmonary veins as they enter the LA. The first patient who underwent the modified procedure demonstrated sinus rhythm on Holter monitoring postoperatively and remained in sinus rhythm following burst atrial pacing at 300 and 420 beats/min each for 30 seconds. In addition, atrial contractions were found to contribute 19% of the cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMed1994

Effect of transcutaneous electrical nerve stimulation on coronary blood flow.

BACKGROUND: Although neurostimulation has been shown to be of benefit in angina pectoris, the exact mechanism of its action is not clear. This study was performed to examine the effect of transcutaneous electrical nerve stimulation on coronary blood flow. METHODS AND RESULTS: The effect of transcutaneous electrical nerve stimulation was studied in 34 syndrome X patients (group 1), 15 coronary artery disease patients (group 2), and 16 heart transplant patients (group 3). Coronary blood flow velocity (CBFV) in the left coronary system was measured at rest and after a 5-minute stimulation period with a Judkins Doppler. There was a significant increase in the resting CBFV in group 1 (from 6.8 +/- 4.1 to 10.5 +/- 5.7 cm/s, P < .001) and group 2 (from 6.8 +/- 4.1 to 10.5 +/- 5.7 cm/s, P < .001). However, there was no significant change in the resting CBFV in group 3. There were no significant changes in the coronary arterial diameters as a result of neurostimulation. There was a significant decrease in the epinephrine levels in group 1 (from 79.6 +/- 17.8 to 58.5 +/- 17.5 ng/L, P = .01) and group 2 (from 102.2 +/- 27.2 to 64.1 +/- 19.1 ng/L, P = .01). CONCLUSIONS: Transcutaneous electrical nerve stimulation can increase resting coronary blood flow velocity. The findings suggest that the site of action is at the microcirculatory level and that the effects may be mediated by neural mechanisms.

Aged↗
PubMed1994

Is coronary flow reserve in response to papaverine really normal in syndrome X?

BACKGROUND: An impaired coronary flow reserve in syndrome X has been demonstrated by many studies. Recently, however, a normal coronary flow reserve in response to papaverine was reported, but the number of patients in these studies was small. The aim of this study was to investigate whether coronary flow reserve in response to intracoronary papaverine is really impaired in syndrome X. METHODS AND RESULTS: We investigated 53 syndrome X patients (typical angina, a positive exercise test, and completely normal coronary arteries on angiography) and 26 heart transplant patients with normal coronary arteries (control group). All antianginal medications were stopped 48 hours before the study. A 3.6F intracoronary Doppler catheter was positioned in the proximal left anterior descending coronary artery and was connected to a Millar velocimeter. The coronary blood flow velocity at rest and in response to a hyperemic dose of papaverine was measured. Coronary flow reserve was defined as the ratio of hyperemic coronary blood flow velocity in response to papaverine and resting coronary blood flow velocity. The coronary flow reserve (mean +/- SD) in the syndrome X group was 2.72 +/- 1.39. The coronary flow reserve in the control group was significantly higher at 5.22 +/- 1.26 (P < .01). In both groups there was no significant difference in the heart rate or the mean arterial pressure during the study. CONCLUSIONS: Our study shows that coronary flow reserve in response to intracoronary papaverine is impaired in syndrome X patients.

Adult↗
PubMed1994

Measurements of human coronary vascular impedance.

The aim of this study was to develop a method of measuring human coronary circulation impedance in a clinical setting. The authors measured coronary flow reserve (CFR) in 27 patients with chest pain and normal coronary arteries. A Judkins-style, 8F Doppler-tipped angiographic catheter was positioned in the left coronary ostium. Resting coronary flow velocity (RFV) and response to a hyperemic 12 mg intracoronary dose of papaverine (PFV) were measured. The signals were recorded by a recorder connected to a microprocessor with analogue-to-digital converter and a maths coprocessor. Using this the authors could obtain values for impedance at RFV (IR) and at PFV (IP). The CFR was defined as the ratio: PFV/RFV. An impedance index (II) was obtained as the ratio of coronary vascular impedance at peak hyperemia to the impedance at rest. The CFR was 3.2 +/- 1.2 and the II was 0.33 +/- 0.11. There was a strong inverse correlation between the CFR and the II (r = -0.9). The authors conclude that this new approach may allow a further insight into the coronary pathophysiology and may become useful in clinical cardiology, eg, in the assessment of heart transplant and Syndrome X patients.

Adult↗
PubMed1993

Effect of oesophageal acid instillation on coronary blood flow.

To assess whether gastrointestinal factors can cause chest pain ("linked angina"), we studied the effect of oesophageal stimulation with acid on coronary blood flow in 20 syndrome X patients. Coronary blood flow velocity (CBFV) was measured with an intracoronary doppler catheter positioned in the proximal left anterior descending coronary artery. Acid stimulation produced typical anginal pain in 11 patients. Mean CBFV was significantly reduced from 7.3 (SD 4.0) to 4.4 (2.8) cm/s. Gastro-oesophageal reflux leading to reduced coronary blood flow may be a mechanism to explain linked angina.

Adult↗
PubMed1993

"Syndrome X" and coronary artery disease.

BACKGROUND: "Syndrome X" is a heterogeneous disorder that probably encompasses several disease states. The long-term prognosis in syndrome X is good, although a significant number of patients continue to experience chest pain and remain functionally limited. Several studies have reported that the development of coronary artery disease in patients with syndrome X is rare. Our experience, however, has shown that patients diagnosed as having syndrome X may develop atherosclerotic coronary artery disease over a relatively short period of time. METHODS: Three patients with syndrome X were studied with repeat coronary angiography. RESULTS AND CONCLUSIONS: We describe the development of coronary artery disease in three syndrome X patients over a relatively short time after their normal coronary angiogram. Accordingly, the physician should remain alert to this possibility.

Adult↗
PubMed1993

Effect of hyperventilation and mental stress on coronary blood flow in syndrome X.

OBJECTIVES: To assess the effect of hyperventilation and mental stress on coronary blood flow and symptom production in patients with syndrome X. DESIGN: A prospective study. Hyperventilation and mental stress tests were performed on the ward and were repeated in the cardiac catheter laboratory where coronary blood flow velocity was also measured with an intracoronary Doppler catheter in the left anterior descending coronary artery. Oesophageal manometry studies were also performed. PATIENTS: 29 patients with syndrome X (typical anginal chest pain, a positive exercise test, and normal coronary angiogram). SETTING: A regional cardiothoracic centre. RESULTS: Hyperventilation produced typical chest pain in 16 patients on the ward. 13 patients experienced their typical chest pain with mental stress test 5. Ten patients experienced chest pain with both hyperventilation and mental stress tests. This pattern was reproduced exactly when the tests were repeated in the cardiac catheter laboratory. Hyperventilation produced a significant increase in the rate-pressure product during ward and laboratory testing. There was, however, no significant change in the rate-pressure product on mental stress tests. The mean (SEM) coronary flow velocity decreased significantly on hyperventilation in the catheter laboratory from 10.0 (0.92) cm/s to 5.9 (0.72) cm/s (p < 0.001). There was also a significant reduction in the mean (SEM) coronary blood flow velocity on mental stress tests from 9.8 (0.86) cm/s to 7.4 (0.6) cm/s (p < 0.001). This reduction in flow velocity occurred in the absence of any changes in diameter of the left anterior descending artery. Further analysis showed that the coronary flow velocity was reduced significantly in only that group of patients in which hyperventilation and mental stress provoked chest pain. There was a significant increase in the arterial concentrations of noradrenaline on both hyperventilation and mental stress testing. Oesophageal manometry showed abnormalities in 17% of patients. CONCLUSIONS: Both hyperventilation and mental stress can produce chest pain in patients with syndrome X and this is associated with a reduction in coronary blood flow velocity. The results of this study suggests that this reduction in coronary flow occurs as a result of increased microvascular resistance.

Adult↗
PubMed1993

Clinical presentation and functional prognosis in syndrome X.

OBJECTIVES: To assess the effect of clinical presentation on functional prognosis in patients with syndrome X. DESIGN: A prospective study. Patients with syndrome X presenting with unstable angina and stable angina were followed up with a questionnaire to examine their functional state. PATIENTS: 41 patients with syndrome X and unstable angina and 41 patients with syndrome X and stable angina. Syndrome X was defined as typical anginal chest pain, a positive exercise test, and normal coronary angiogram. SETTING: Regional cardiothoracic centre. RESULTS: The mean follow up time was 36 (range 20-51) months for the unstable angina group and 35 (range 19-51) months for the stable angina group. No patient was lost to follow up in either group. At follow up 28 patients in the unstable angina group were pain free compared with 15 patients in the stable angina group (p = 0.008). Seven patients in the unstable angina group had further hospital admission with chest pain after the cardiac catheterisation compared wtih 12 patients in the stable angina group (NS). Seven patients in the unstable angina group believed that they had heart disease compared with 27 in the stable angina group (p < 0.001). 26 patients in the unstable angina group but only eight patients in the stable angina group were unlimited in their physical activity (p < 0.001). 12 patients in the unstable angina group compared with 27 patients in the stable angina group were unable to work normally because of chest pain (p < 0.001). The mean (SD) duration of symptoms before cardiac catheterisation was 7.9 (4.7) months in the unstable angina group and 13.4 (5.6) months in the stable angina group (p < 0.001). 10 patients in the unstable angina group and 24 patients in the stable angina group still attended hospital outpatient clinics because of chest pain (p = 0.004). 16 patients in the unstable angina group and 29 patients in the stable angina group were still taking regular antianginal medication (p < 0.001). CONCLUSIONS: Patients with syndrome X who present with unstable angina have a significantly better functional prognosis than those presenting with symptoms of stable angina. This may reflect differences in underlying pathophysiological mechanisms.

Adult↗
PubMed1993

Coronary flow reserve measurements with a new Judkins-style Doppler angiographic catheter.

The authors assessed whether measurements obtained by Judkins-style Doppler catheters are comparable to those achieved with the intracoronary Doppler technique in 42 patients with normal coronary arteries on angiography (19 syndrome X and 23 heart transplant patients). Resting coronary flow velocity and response to a hyperemic intracoronary dose of papaverine was measured with a Judkins-style, 8F Doppler-tipped catheter positioned in the left coronary ostium and a 3.6F intracoronary Doppler catheter positioned in the proximal left anterior descending artery. Mean coronary flow velocity at rest was significantly higher with the Judkins Doppler (10.1 +/- 4.6 vs 6.3 +/- 4.5 cm/sec, p < 0.01). The mean coronary flow velocity at peak hyperemia was also significantly higher with the Judkins Doppler (33.7 +/- 14.1 vs 19.7 +/- 11.5 cm/sec, p < 0.01). Coronary flow reserve was 3.57 +/- 1.3 with the Judkins Doppler and 3.47 +/- 1.2 with the intracoronary Doppler (r = 0.85). A second study was performed in 14 heart transplant patients with the intracoronary Doppler positioned in the left main coronary artery. The resting and hyperemic flow velocities were again higher with the Judkins Doppler but the differences were not statistically significant. There was again a strong correlation between the Doppler catheters for coronary flow reserve measurements. The Judkins-style Doppler technique appears to be a quick, safe, and accurate alternative to the intracoronary Doppler technique.

Cardiac Catheterization↗