Low output, low gradient aortic stenosis.
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Aortic Valve Stenosis↗
Biomedical subjects
P MacCarthy
Publications and source records attributed to P MacCarthy.
The use of transthoracic echocardiography to guide thrombolytic therapy during cardiac arrest due to massive pulmonary embolism.
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Adult↗
Myocardial bradykinin production during coronary balloon angioplasty in humans.
BACKGROUND: Recent studies have implicated the peptide bradykinin as a potential trigger of ischaemic preconditioning, the phenomenon whereby a brief episode of myocardial ischaemia induces an increased tolerance to subsequent more prolonged ischaemia. Brief myocardial ischaemia occurring during percutaneous transluminal coronary balloon angioplasty in humans is reported to be capable of inducing preconditioning. DESIGN: We studied the intracardiac production of bradykinin in eight patients (seven men, mean age 53.5 years) undergoing elective percutaneous transluminal coronary angioplasty for a single left anterior descending coronary artery stenosis. Paired blood samples were obtained from the coronary sinus and the proximal aorta at baseline, immediately before balloon deflation after a 2-min inflation, and at 1, 3 and 5 min post deflation. Bradykinin levels were measured by radioimmunoassay. RESULTS: There was no significant change either in aortic or coronary sinus bradykinin levels at any time point. CONCLUSIONS: Intracardiac production of bradykinin is unlikely to be a trigger for ischaemic preconditioning after brief myocardial ischaemia in humans.
Adult↗
Nitric oxide enhances the inotropic response to beta-adrenergic stimulation in the isolated guinea-pig heart.
Nitric oxide (NO) exerts several effects on myocardial contraction, including enhancement of relaxation and diastolic function, modulation of beta-adrenergic inotropic responses, and inotropic effects in the absence of agonist pre-stimulation. Different effects have been observed in different species and preparations, and it is unclear whether they are species- or preparation-specific, or whether they represent a range of responses that can manifest in most mammalian species. We therefore examined the effects of NO on the inotropic response to beta-adrenergic stimulation in the isolated guinea-pig heart, a species in which we have previously shown that NO enhances basal left ventricular (LV) relaxation and modulates the Frank-Starling response. Isolated ejecting hearts were perfused with Krebs buffer at constant placed heart rate (1 microM) indomethacin, 37 degrees C, constant loading conditions), and high fidelity LV pressure was monitored by an apical 2 F Millar catheter. All hearts were initially treated with dobutamine (0.1 microM) and then, once the peak inotropic and chronotropic response had been established, with either (a) no further treatment (n = 6), (b) the NO donor sodium nitroprusside (1 microM, n = 6; 10 microM, n = 6), or (c) the specific agonist for NO release, substance P (0.1 microM, n = 6). Dobutamine (0.1 microM) produced a rapid positive inotropic and chronotropic response, associated with a fall in LV end-diastolic pressure (LVEDP) and a rise in coronary flow. The positive inotropic effect of dobutamine declined over 20-28 minutes, while the chronotropic response persisted over this period. Low dose sodium nitroprusside (1 microM) delayed the decline in the inotropic response to dobutamine and exaggerated the fall in LVEDP. Similar effects were observed with substance P (0.1 microM). In contrast, a higher dose of sodium nitroprusside (10 microM) did not alter the response to dobutamine. These data indicate that "low dose" NO augments the inotropic response to beta-adrenergic stimulation in the isolated ejecting guinea-pig heart, in addition to its previously reported effects on basal LV relaxation in the same preparation.
Adrenergic beta-Agonists↗
The arterial basis of pharyngeal flaps.
The arterial basis of pharyngeal flaps is unknown. Injection and dissection studies have been used in 41 adult human cadavers to study the arterial supply of pharyngoplasties in current use. Superiorly based posterior pharyngeal flaps are "random" in nature, inferiorly based posterior pharyngeal flaps may include an "axial" vessel, laterally based posterior pharyngeal flaps will include an "axial" vessel, and laterally based "sphincter" pharyngoplasties, although supplied segmentally, will contain an "axial" vessel if raised up to but not beyond the upper pole of the tonsil.
Adult↗
The arterial supply of the palate: implications for closure of cleft palates.
Little is known of the arterial anatomy of the palate. Injection studies and dissection of a total of 49 cadavers have shown the principal arterial supply of the soft palate to be the ascending pharyngeal artery, which anastomoses with the greater palatine artery at the junction of the hard and soft palates. The position and relations of the branches of the ascending palatine artery put it at risk during palate repair.
Aged↗
Motor recovery after acute ischaemic stroke: a metabolic study.
The metabolic changes occurring after ischaemic stroke were measured to investigate the functional anatomy of clinical motor recovery. Positron emission tomography (PET) and the steady-state 15O technique was used to compare resting relative metabolic distributions at the onset of functional deficit with those following recovery. Ten patients were studied with repeat scans. Motor recovery was associated in some patients with an increase of relative oxygen metabolism in anatomical structures normally involved in motor function in the affected hemisphere, particularly in the cortical motor areas. In those patients without such metabolic changes in the cortex of the diseased hemisphere, relative increases in cortical metabolism in the contralateral hemisphere were associated with better motor recovery than in patients with no relative cortical metabolic increase in either hemisphere. There was no correlation between the degree of improvement in motor function and the severity of motor deficit at onset, the size and site of the lesion and the metabolic changes in the infarcted zone. No particular pattern of global metabolic changes was observed after recovery. Thus different relative patterns of metabolic recovery were seen in patients with different lesions and evidence was found for the participation of contralateral structures in the recovery process in some patients.
Acute Disease↗
Excess sucrose and glucose ingestion acutely elevate blood pressure in spontaneously hypertensive rats.
Spontaneously hypertensive rats (SHR) were fed 6 different diets. The baseline diet (I) derived equal calories from sucrose, proteins, and fats. Three other diets (II, III, VI) derived the majority of calories from refined CHO, sucrose or glucose, with decreases in calories from proteins or fats. The last two diets (IV, V) were relatively low in sucrose with a higher percentage of the total calories from proteins and fats, respectively. From 3 to 15 weeks on the diets, the highest average BP was in rats consuming high concentrations of sucrose or glucose (II, III, VI). Urinary excretory rates of norepinephrine (NE) at 5, 10 and 15 weeks and epinephrine at 5 and 10 weeks were significantly elevated in rats ingesting diets high in refined CHO, and NE positively correlated with blood pressure (BP) at 5 and 10 weeks of the study. At the end of the study, serum insulin levels were not different, but plasma renin and serum glucagon levels were lower in SHR consuming the diets with high CHO concentrations. We conclude that equally elevated BP are seen with relatively high intakes of either sucrose or glucose, whether the balance of calories is derived from lessening fat or protein. This is secondary, at least in part, to alterations in NE metabolism.
Animals↗
Changes of plasma renin activity and atrial natriuretic factor during intravenous nicardipine treatment of severe hypertension.
Intravenous nicardipine was given to 32 severe hypertensive patients in an increasing dose, titration fashion. Samples for plasma renin activity and plasma atrial natriuretic factor concentration were obtained at the following times: before treatment, at the time of titration response and at the end of a maintenance period. The mean time required to achieve the titration response was 29 min. Plasma renin activity was increased by 32% (p less than 0.05) at the titration response and 181% (p less than 0.005) at the end of an 8-12 h maintenance nicardipine infusion. Atrial natriuretic factor concentration was unchanged from baseline at titration response and was decreased by 25% (p less than 0.005) at the end of maintenance. Mean plasma nicardipine dose was 6.95 mg/h at the titration response and 8.76 mg/h at the end of maintenance. These results suggest that alterations in plasma renin activity and atrial natriuretic factor concentrations may be associated with blood pressure reduction rather than with a direct drug action on release mechanisms.
Atrial Natriuretic Factor↗
Management of hypertension newly detected by health screening.
An attempt was made, through a hospital-based health screening service, to ensure proper longterm care of clients with hypertension and other cardiovascular risk factors. Of 8755 subjects screened on one occasion, 1274 (14.6%) had a blood pressure reading above defined limits; of these, 1058 were not receiving antihypertensive drugs. Apparently hypertensive subjects were rescreened within one week or were referred to their local doctors. At their second visits, over half of the 716 rescreened subjects had reading consistently below the defined limits. Those with intermittent blood pressure elevation (89 patients) were designated as having labile hypertension, and were reviewed regularly. The remainder, with persisting hypertension, were sent to their local doctors or to the hospital's hypertension clinic. After six months, the group ith labile hypertension showed no change in mean left cardiac ventricular voltage, and more than 50% the group had normal blood pressure; 14 patients were receiving antihypertensive drugs. Subjects referred to the hypertension clinic had a high prevalence of cardiovascular risk factors and a low prevalence of clinically evident organ damage. Only half of this group were deemed to require drug therapy. In a postal survey of clients referred to private doctors, 35% of respondents reported that they had started taking anti-hypertensive drugs. Thorough rescreening of blood pressure is essential in preventing the unnecessary use of antihypertensive drugs, and this can be facilitated by providing management streams appropriate to the needs of the individual subject.
Adolescent↗
Implications of a selective policy in the management of spina bifida.
Of 307 patients with myelomeningocele 132 were treated nonoperatively during the 6 yr period from 1973 to 1978. Of the nonoperatively managed patients, 86% died within 1 yr. The policy of nonoperative management was changed to one of active intervention in 25% of the infants. Despite this a large number died.
Humans↗
Non-renin-mediated renovascular hypertension.
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Hypertension, Renal↗
Clinical dose-response studies with guanfacine (BS 100-141), a new antihypertensive agent.
1. Blood pressure, pulse rate, salivary flow and the degree of sedation were recorded at intervals following oral administration of single doses of guanfacine, a clonidine-like agent, to hypertensive patients. 2. Between 2 and 10 h after administration of guanfacine (3 mg or 5 mg), there were dose-related decrease in lying and standing blood pressure, together with significant reductions in pulse rate and salivary flow. 3. It is concluded that guanfacine lowers blood pressure in hypertensive patients and is probably suitable for twice daily administration, but produces xerostomia and sedation.
Antihypertensive Agents↗
Assessing and counselling trainees.
Increasing attention to the training of junior doctors and the changes in career structure outlined in the Calman Report make effective assessment and counselling of trainees in medicine essential. A conference held at the Royal College of Physicians on 5 October 1994 considered some of the problems and practicalities of incorporating such developments into new training programmes.
Education, Medical, Graduate↗