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Biomedical subjects

C M Bellamy

Publications and source records attributed to C M Bellamy.

At least 19 recordsLinked to original sources
PubMed1995

Vasoconstrictor peptides and cold intolerance in patients with stable angina pectoris.

BACKGROUND: The exact mechanism that explains the phenomenon of cold intolerance in patients with angina remains controversial. Although the response to the effects of a cold environment has been examined in these patients, their response to cold air inhalation has produced conflicting results. In addition, the possible role of vasoactive peptides in the pathophysiology has not been explored. OBJECTIVES: The aims of this study were to examine the response of patients with stable angina to the effects of cold air inhalation during exercise testing, and to investigate the possible role played by the vasoconstrictor peptides endothelin-1 (ET-1) and angiotensin-II (AT-II) in the pathophysiology. METHODS: In a randomised order, 12 men with stable angina, whose medication had been stopped, underwent two separate symptom limited treadmill exercise tests. At one visit the patients exercised while breathing room air and at the other visit they exercised while breathing cold air from a specially adapted freezer. Serial peripheral venous blood samples were taken for ET-1 and AT-II estimations during each visit. RESULTS: Cold air inhalation resulted in a significant reduction in the mean time to angina (232.7 (20.4) s v 274.1 (26.9) s, P = 0.04) and the mean total exercise time (299.5 (27.0) s v 350.3 (23.9) s, P = 0.008), but no significant change in the time to 1 mm ST depression (223.3 (29.0) s v 241.3 (29.2) s, P = 0.25). There was no significant difference between the rate-pressure products at the onset of angina (P = 0.13) and the time to 1 mm ST depression (P = 0.85), but at peak exercise the rate-pressure product was significantly lower in patients breathing cold air as opposed to room air (P = 0.049). There was an equivalent significant decrease in ET-1 concentrations at peak exercise compared with that at rest at both visits (room air 5.0 (0.7) pmol/l v 4.3 (0.7) pmol/l, P = 0.03; cold air 4.4 (0.6) pmol/l v 3.8 (0.5) pmol/l, P = 0.02). There was a significant increase in AT-II concentrations 10 min after peak exercise in patients breathing room air (39.2 (6.1) pmol/l v 32.1 (4.8) pmol/l, P = 0.01) which was not repeated during cold air inhalation (36.6 (3.4) pmol/l v 28.3 (3.4) pmol/l, P = 0.07). CONCLUSIONS: Cold air inhalation in patients with stable angina results in an earlier onset of angina and a reduction in exercise capacity. Both peripheral and central reflex mechanisms appear to contribute to the phenomenon of cold intolerance. Peripheral ET-1 and AT-II do not appear to play a significant role in the pathophysiology.

Aged↗
PubMed1994

Transmitral Doppler assessment of left ventricular diastolic function during coronary artery bypass surgery.

OBJECTIVE: To evaluate which Doppler transmitral velocity indices of left ventricular diastolic function change with alteration of left ventricular filling pressure. METHODS: Twenty-two patients undergoing coronary artery bypass surgery. The effect of fluid loading on indices derived from the transmitral Doppler waveform, recorded by a trans-oesophageal echocardiography, was evaluated using a generalised linear statistical model. RESULTS: E-wave maximum velocity, E-wave acceleration time and slope, E-wave deceleration slope, A-wave maximum velocity and E/A wave maximum velocity ratio showed significant changes after alterations in left ventricular filling pressure. E-wave deceleration time and E-wave maximum velocity/time velocity integral showed no significant change after fluid loading. CONCLUSION: Several commonly used Doppler derived indices of left ventricular diastolic function are significantly affected by changes in filling pressure of the left ventricle. This may limit the usefulness of the Doppler method for serial assessment of diastolic function when the left ventricular filling pressure has changed between assessments. Only the E-wave deceleration time did not show significant changes and might be a useful Doppler index for the serial measurement of left ventricular compliance but this needs to be confirmed with haemodynamic measurements.

Adult↗
PubMed1994

Free-radical activity after primary coronary angioplasty in acute myocardial infarction.

Free-radical activity in coronary venous outflow was assessed before and after reperfusion in nine patients with acute infarction who had undergone successful recanalization of the infarct-related artery by primary coronary angioplasty. Free-radical activity was measured in serum samples from coronary venous outflow over a timed period of 24 hours by using (1) the percentage molar ratio (PMR) of the diene conjugate 9,11-linoleic acid, and (2) malonaldehyde concentration. Preangioplasty PMR means lay within the normal range, but showed a marked increase soon after successful recanalization. Relative to baseline, the changes over time reached statistical significance between 2 and 60 minutes. No statistically significant changes in malonaldehyde occurred over the study period. We conclude that successful recanalization of the infarct artery is associated with significantly elevated free-radical activity, as measured by the PMR of conjugated diene, in coronary venous outflow. Such patients may be at risk from free radical mediated reperfusion injury.

Adult↗
PubMed1994

Early experience of directional coronary atherectomy: clinical results, complications and histopathological findings.

OBJECTIVE: To report the early experience, clinical results and histopathologic findings of Directional Coronary Atherectomy from a UK centre experienced in coronary angioplasty. DESIGN: Prospective study of the first 45 Directional Coronary Atherectomy (DCA) procedures using the Simpson coronary atherectomy device. RESULTS: Forty-five procedures were performed in 33 male and 5 female patients (mean age, 55.1 years). Directional Coronary Atherectomy was performed to 50 lesions (39 de novo, 11 restenosis; 44 left anterior descending, 3 right, 2 circumflex coronary arteries and 1 saphenous vein graft). Clinical and primary angiographic success was achieved in 43 of 45 cases (95.5%) and in 47 of 50 lesions (94%) after DCA alone. Before DCA the mean diameter stenosis was 88.7% (range, 50-100%) but following DCA (and percutaneous coronary angioplasty (PTCA) if necessary) the mean diameter stenosis was 3.5% (range, 0-15%; P < 0.001). Complications included occlusive dissection requiring coronary artery bypass surgery in two patients; abrupt closure of right coronary artery in one patient successfully reopened by PTCA and thrombolysis, complicated by excessive blood loss; reversible coronary artery spasm due to minor nose-cone trauma in four patients and temporary side branch loss in one patient. There were no coronary artery perforations, guide catheter complications, peripheral vascular trauma or deaths. On average 5.6 specimens (range, 1-18) were removed per case. Histology showed fibrous intimal plaque in 98%, media in 39% and adventitia in 7%. Neo-intimal hyperplasia was found in all restenosis lesions but also in 30% of de novo lesions. CONCLUSIONS: This small initial series indicates that directional coronary atherectomy is an effective and safe procedure for the treatment of obstructive coronary artery disease in carefully selected patients. With care, a high success rate can be achieved even during a learning phase. The technique is particularly effective for morphologically complex lesions that are unfavourable for PTCA. The procedure is unlike PTCA and requires additional training if pitfalls are to be avoided, high success rates achieved and complication rates kept low.

Adult↗
PubMed1994

Stability of the DDD pacing mode in patients 80 years of age and older.

We reviewed the records of 119 consecutive patients aged 80 years or older (mean age 84 +/- 3.7 years) in whom a dual chamber pacemaker was implanted between 1984 and 1991. Follow-up data was available up to February 1993. Immediate postimplantation complications were rare. Nine patients were lost to follow-up, all within 6 months of implantation. An additional seven patients died within 6 months of implantation. Long-term follow up for at least 6 months from implantation was available for 103 of the 119 patients (87%). Of these 89 (86%) remained in functioning DDD mode for a mean of 22 +/- 15 months from implantation. Nine patients were reprogrammed to VVI mode, six due to atrial fibrillation and three due to failure of atrial sensing or pacing. One patient was programmed DVI for failure of atrial sensing; 94 of 112 patients (84%) whose status was definitely known in February 1993 remained in functioning DDD mode until death or last follow-up. Cumulative survival in DDD mode was 78% at 30 months. We conclude that DDD pacing is stable in the great majority of patients in their ninth and tenth decades who present with rhythms amenable to dual chamber pacing and who have no history of sustained atrial fibrillation.

Aged↗
PubMed1993

Free-radical generation during angioplasty reperfusion for acute myocardial infarction.

We describe direct and quantitative evidence of free-radical production in the early stage after recanalisation in a patient undergoing primary coronary angioplasty for acute myocardial infarction. After successful initial dilation, the procedure was complicated by re-occlusion of the artery at the same site, with subsequent fall in free-radical generation. After repeat angioplasty, recanalisation was again accompanied by increased free-radical production.

Angioplasty, Balloon, Coronary↗
PubMed1993

Traumatic mitral valve rupture during the Hillsborough football disaster: case report.

Ninety-five spectators died from crush injuries and asphyxiation at the Hillsborough football ground in Sheffield, England on April 15, 1989. Survivors suffered a spectrum of compression injuries to the chest, including documented cardiac injuries although these were not permanent. We report the case of one survivor who developed an isolated traumatic mitral valve rupture during the crush, and may require mitral valve replacement at a later date.

Echocardiography↗
PubMed1993

Histopathological examination of specimens removed during directional coronary atherectomy in patients presenting with crescendo angina show mural thrombus.

Thrombus formation over a fissured coronary atheromatous plaque has been shown by post mortem histological examination to be the pathophysiological mechanism responsible for myocardial ischaemia in those patients who died following a crescendo pattern of angina. Histological examination of plaques responsible for a crescendo pattern of angina in patients who do not die has not been available until recently. We describe two patients who presented with a crescendo pattern of angina. A new technique of coronary revascularization, directional coronary atherectomy, produced symptomatic relief and resolution of myocardial ischaemia. Histological examination of material from the stenosis responsible for their myocardial ischaemia, obtained using this technique, confirmed thrombus formation overlying a fissured atheromatous plaque.

Adult↗
PubMed1992

Normothermic arrest with continuous hyperkalaemic blood: initial experience.

The requirement for hypothermia in myocardial protection has recently been questioned. Between October 1990 and May 1991, diastolic arrest was achieved using continuous perfusion with normothermic, hyperkalaemic blood in 257 consecutive patients undergoing cardiac surgery. The mean age was 59.8 +/- 9.3 years (range 28-84 years). Coronary artery surgery was performed in 210 patients, valve replacements in 18, combined procedures in 22, and 7 patients had miscellaneous procedures. Eleven patients (4.3%) had undergone previous cardiac surgery, and 65 (25.3%) required urgent or emergency operations. Hyperkalaemic blood (7-20 mmol/l) was delivered antegradely in 190 (72.8%) patients (mean aortic root pressure 60-80 mmHg), retrogradely in 62 (25.3%) patients (mean coronary sinus pressure less than 40 mmHg), and by a combined route in 5 (1.9%). Sinus rhythm returned immediately after removal of the aortic clamp in 235 (91.4%) patients. Weaning from bypass was achieved without circulatory support in 207 (82.5%) patients. Of 233 patients undergoing non-emergency coronary artery surgery, single valve or combined procedures, 11 died, giving an operative mortality of 4.7%. Of 155 patients with good left ventricular function requiring coronary artery surgery, 3 (1.9%) died. The in-hospital mortality for the group as a whole was 7.3%. Sixteen (6.2%) patients sustained perioperative myocardial infarctions; of these 6 died. We conclude that continuous, normothermic, hyperkalaemic arrest is a simple and safe method of myocardial protection. It may avoid the damage associated with hypothermia, ischaemia and reperfusion.

Adult↗
PubMed1992

Can supplementation of diet with omega-3 polyunsaturated fatty acids reduce coronary angioplasty restenosis rate?

The objective of this blinded, randomized, prospective study was to assess whether supplementation of normal diet with omega-3 polyunsaturated fatty acids can reduce angiographically defined restenosis following coronary angioplasty. The study included all patients undergoing coronary angioplasty in this institution between January 1988 and January 1989. One hundred and twenty patients enrolled, 60 in each treatment group. All were randomized to either supplementation of normal diet with 3 g of omega-3 polyunsaturated fatty acids per day started 1-2 days prior to angioplasty and continued for 6 months (treatment group), or to receive standard therapy only (control group). Quantitative angiographically defined restenosis was assessed at 6 months post angioplasty. Restenosis occurred in 27.8% (95% CI 18.0-37.7%) of lesions in the treatment group and in 28.3% (CI 16.9-39.7%) of lesions in the control group, but the difference was not statistically significant. The study showed that diet supplemented with 3 g of omega-3 polyunsaturated fatty acids started 1-2 days preceding angioplasty does not reduce angiographically defined restenosis rate.

Angina Pectoris↗
PubMed1992

Comparative evaluation of rate modulation in new generation evoked QT and activity sensing pacemakers.

Two new generation rate adaptive pacemakers, the Rhythmyx (Vitatron) using the evoked QT interval and the Legend (Medtronic) using vibration as indicators of metabolic demand, were compared for rate adaptive characteristics during different forms of exercise. While both showed improvements over previous generation pacemakers, they still show deficiencies in some aspects of rate modulation. Rhythmyx was slow to respond to changes in metabolic need and showed an "over-shoot" with increasing pacing rate on cessation of exercise. Legend was quick to adapt rate at beginning and end of exercise but showed a plateaus of rate modulation during the period of slowly increasing workload. Legend also showed only modest rate adaptation to changes in treadmill gradient and to bicycle ergometer exercise. Further developments in pacemaker technology are required if physiological rate adaptation to exercise is required.

Aged↗