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Biomedical subjects

T R Shaw

Publications and source records attributed to T R Shaw.

At least 37 records · Page 2Linked to original sources
PubMed1994

Anterior staircase manoeuvre for atrial transseptal puncture.

OBJECTIVE: Assessment of an anterior staircase modification to the standard atrial transseptal technique. DESIGN: Retrospective report on patients undergoing atrial transseptal puncture. SETTING: A regional cardiac centre. PATIENTS: A series of 658 patients catheterised between 1975 and 1991. RESULTS: Needle entry to the left atrium was obtained in 647 (98.3%) patients with needle and catheter entry to the left atrial cavity in 637 patients (96.8%). Sustained atrial arrhythmia occurred in six patients (0.9%) and pronounced bradycardia in one. Cardiac perforation occurred in three patients (0.5%) but did not cause cardiac tamponade. There were no deaths or embolic complications caused by the transseptal puncture. The anterior staircase manoeuvre was particularly useful in patients with problem septa--that is, when the septum bulged into the right atrial cavity, lacked a detectable limbic edge, was tough or tender, or when the right atrium was considerably enlarged. CONCLUSION: The anterior staircase technique is a useful modification to the atrial transseptal puncture technique because it allows repeated passage down the atrial septum without the need for guidewire and needle exchanges for repositioning in the superior vena cava.

Cardiac Catheterization↗
PubMed1994

Pseudoaneurysm of the femoral artery after cardiac catheterisation: diagnosis and treatment by manual compression guided by Doppler colour flow imaging.

OBJECTIVE: To assess the value of Doppler colour flow imaging for diagnosing and guiding non-surgical treatment of pseudoaneurysm of the femoral artery complicating cardiac catheterisation. DESIGN: A prospective study. SETTING: Cardiac department in a teaching hospital. PATIENTS: 9 patients (8 female, 1 male) who presented with pseudoaneurysm 1-15 days after cardiac catheterisation. INTERVENTIONS: The femoral arterial communication to the false aneurysm was localised by Doppler colour flow imaging. Manual pressure was then applied to the ultrasound transducer which was positioned directly over the site of the arterial communication. Pressure was progressively increased until it was sufficient to prevent colour flow from the artery into the false aneurysm cavity while allowing Doppler flow to continue within the arterial lumen. MAIN OUTCOME MEASURES: Characteristics of pseudoaneurysm, duration of manual compression, success rate, follow up. RESULTS: The pseudoaneurysms ranged from 1.3 to 5.5 cm in length. Six pseudoaneurysms were 1.3-2.0 cm away from the arterial puncture. The pseudoaneurysm was closed in 8/9 patients by compression exerted manually through the transducer for 25-40 minutes (3 successful cases required two or three periods of compression within 48 hours). No pseudoaneurysm recurred during 14-61 days of follow up. CONCLUSIONS: Most pseudoaneurysms of the femoral artery can be treated by a period of manual pressure applied with an ultrasound transducer and guided by Doppler colour flow.

Adult↗
PubMed1994

A comparison of cylindrical and Inoue balloon techniques for mitral valvotomy in patients in the United Kingdom.

OBJECTIVES: To compare the use of cylindrical balloons and the Inoue balloon for percutaneous mitral valvotomy in patients in the United Kingdom. DESIGN: Comparison of the haemodynamic results, complications, and symptomatic outcome of balloon dilatation for mitral stenosis in consecutive patients treated by cylindrical balloons and a second consecutive series of patients treated by the Inoue balloon. SETTING: A tertiary cardiac referral centre in Scotland. PATIENTS: 70 patients (mean age 60.6 years) treated by the single or double cylindrical balloon technique and 70 patients (mean age 58.9 years) treated with the Inoue balloon method. MAIN OUTCOME MEASURES: Success in obtaining dilatation at the mitral orifice, procedure and screening times, increase in valve area, complications, and early symptomatic outcome. RESULTS: Dilatation of the mitral valve was obtained in 91% of patients when cylindrical balloons were used and in 99% of patients treated with the Inoue balloon. Use of the Inoue balloon gave significantly shorter procedure and screening times. Technical problems in obtaining and maintaining the position at the mitral orifice were more common with cylindrical balloons. Improvements in valve area and symptoms were not significantly different with use of the two types of balloon. The Inoue balloon avoided cardiac tamponade and the creation of larger atrial septal defects, but had a higher incidence of increase in mitral reflux. CONCLUSIONS: In these elderly patients, the Inoue balloon method was safer and faster for percutaneous mitral valvotomy, with a higher success rate for dilatation within the valve orifice. Haemodynamic and symptomatic improvement was similar with the two techniques.

Adolescent↗
PubMed1994

Success of audit in reducing the time taken to administer thrombolysis and aspirin in patients with acute myocardial infarction.

We assessed whether audit might reduce the time taken to give thrombolysis and aspirin in patients with acute myocardial infarction (N = 116). A retrospective analysis was performed of the sources of delay in giving the drugs (N-60) and the data were presented to clinical staff accompanied by guidelines aimed at eliminating delays. A prospective survey was undertaken (N = 56) after these interventions. Audit resulted in an overall 31% reduction (P = 0.013) in the time to administer thrombolysis (median 55 minutes [range 21-148] v 38 [15-155]): there was a 57% fall (P < 0.0001) in the time to record an electrocardiogram (14 minutes [4-34] v 6 [1-19]) and a 33% decrease (P = 0.047) in the time taken to begin thrombolysis in the coronary care unit (15 minutes [0-110) v 10 [5-70]). The time taken to give aspirin was also reduced (P = 0.001) from 58 minutes (15-400) to 15 (3-235). The time taken to administer thrombolysis and aspirin to patients admitted with acute myocardial infarction can be reduced by audit.

Adult↗
PubMed1993

The comparative value of transesophageal and transthoracic echocardiography before and after percutaneous mitral balloon valvotomy: a prospective study.

Transthoracic (TTE) and transesophageal echocardiography (TEE) were performed prospectively on 53 consecutive patients (mean age 59 +/- 14 years) immediately before and within 24 hours of mitral balloon valvotomy to compare the relative value of the two techniques. Biplane TEE was used in 38 patients and single-plane imaging was done in 11. All patients underwent left and right cardiac catheterization, left ventriculography, and coronary angiography. While TEE provided excellent images of the mitral valve in all patients, imaging planes were more limited than by TTE. Mitral valve morphology could be assessed satisfactorily by either technique. Echo scores derived from each showed good correlation (r = 0.90, p < 0.001). TEE transgastric longitudinal scanning provided superior detail of the subvalvar apparatus but only in 20 (53%) of 38 patients. Patients with good transgastric views had significantly smaller left atrial volumes than those without (58 +/- 22 vs 106 +/- 41 cm3, p < 0.001). Mitral valve orifice and the commissures were better assessed by TTE. Before valvotomy, mitral regurgitation (MR) graded by TEE and TTE color flow mapping was concordant with angiography in 80% and 81%, respectively. After valvotomy, TTE color flow mapping failed to detect MR in two of the three patients who developed severe MR. Two of these patients were examined by TEE, which demonstrated both the MR jets as well as leaflet tears. Thrombus was diagnosed in the left atrium in eight patients by TEE and in only one patient by TTE. Biplane TEE was required for accurate thrombus localization and for assessing its size and extent. Five patients with thrombus underwent balloon valvotomy without complications. Left-to-right atrial shunting was detected by TEE and TTE in 95% and 48% of patients, respectively. Flow convergence regions, from which quantitative flow information can be derived, were imaged by TEE only. TTE and TEE have complementary roles. However, TEE is essential for excluding thrombus in the left atrium before balloon valvotomy. After the procedure, TEE is recommended for the evaluation of patients with severe mitral regurgitation.

Adolescent↗
PubMed1993

A multicentre, double-blind, placebo-controlled trial of quinapril in mild, chronic heart failure.

Angiotensin converting enzyme (ACE) inhibitors are of proven value in patients with severe chronic heart failure (CHF). Studies of the effects of ACE inhibitors on exercise capacity and quality of life in mild CHF have produced conflicting results. We have studied the effects of quinapril, a new ACE inhibitor with a relatively short plasma half-life, in mild CHF. Once daily (o.d.) dosing was compared with twice daily (b.i.d.) dosing in a three-way cross-over, double-blind, placebo-controlled trial. Thirty-two patients (two female), mean age 59 (range 32-76) years were enrolled in three cardiology centres in the U.K. in 29 patients, and non-ischaemic in three. The mean (range) radionuclide ejection fraction was 20.4% (8%-47%). Following full familiarization with the protocol, the treadmill exercise time (modified Bruce protocol) was determined for each patient during a placebo run-in phase, and at the end of each of three 8-week double-blind treatment phases with quinapril o.d., quinapril b.i.d. (maximal total daily dose 20 mg) and placebo. Three patients were withdrawn due to adverse events while receiving quinapril (unstable angina, exacerbation of CHF and arrhythmia); there were no deaths and no patient was withdrawn due to hypotension. Mean exercise time (the primary end-point) was 65 s and 53 s longer in patients receiving quinapril o.d. and b.i.d. respectively compared to placebo (both P < 0.01, ANOVA). There was no significant period effect during the trial and no significant difference between the two quinapril dosing regimens. Quinapril had no significant effect on secondary end-points including ejection fraction, functional class and quality of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Quantification of left-to-right atrial shunting and defect size after balloon mitral commissurotomy using biplane transesophageal echocardiography, color flow Doppler mapping, and the principle of proximal flow convergence.

BACKGROUND: The flow convergence region (FCR), a zone of progressive laminar velocity acceleration, can be imaged by color Doppler proximal to stenotic and regurgitant orifices. Theoretically, FCR proximal to a discrete circular and planar orifice consists of concentric hemispheric shells of equal and accelerating velocities centered at the orifice. According to the continuity principle, flow rate across any of these isovelocity surfaces equals flow rate through the orifice. The aim of this study was to investigate whether these principles could be applied to quantify left-to-right shunting and the size of atrial septal defects after balloon mitral commissurotomy. METHODS AND RESULTS: Biplane transesophageal echocardiography (TEE) with color flow imaging was performed on 36 consecutive patients (mean age, 57 +/- 16 years; range, 14-78 years) immediately before and within 24 hours of balloon (Inoue, n = 33; Mansfield, n = 3) mitral commissurotomy. Left-to-right atrial shunting was detected by TEE in 33 patients (92%) and by oximetry in 11 patients (31%). The radius r of FCR was measured from the first aliasing limit, at a Nyquist velocity reduced to 11 cm/sec by zero-shifting, to the orifice in the atrial septum. FCR was assumed to be hemispherical. Hence, flow rate (Q) was calculated as 2 pi r2 Vr, where Vr is the velocity at a radial distance r. The velocity profile of transatrial flow was assessed by means of high pulse repetition frequency, from which the maximum flow velocity (Vp) and the velocity-time integral (VTI) were obtained. The flow area of the atrial septal defect was calculated as Qm, the maximal flow rate, divided by Vp. Hence, shunt flow was calculated as flow area x VTI x heart rate. FCR was analyzed in two orthogonal planes. Mean Qm (38.1 +/- 26.5 versus 5.3 +/- 2.7 mL/sec), flow area (22.1 +/- 11.2 versus 4.4 +/- 2.0 mm2), and shunt flow (1,590 +/- 1,070 versus 200 +/- 130 mL/min) on transverse plane imaging were all significantly higher in patients with shunts detected by oximetry than in those without. Similar results were obtained from longitudinal plane imaging. Qm correlated well with oximetric shunt flow (r = 0.89-0.94, p < 0.001) and shunt ratio (r = 0.91-0.94, p < 0.001). Flow area correlated closely (r = 0.93-0.94, p < 0.001) with area determined by direct measurement from two-dimensional echocardiography. Shunt flow determined by FCR also correlated closely (r = 0.94-0.98, p < 0.001) with that determined by oximetry and that derived from two-dimensional echocardiography and pulsed Doppler (r = 0.96, p < 0.001). CONCLUSIONS: The flow convergence region imaged by TEE color flow mapping provides new and accurate quantitative information on atrial shunt flow and defect size after balloon mitral valvotomy. It is a quick, reliable, and fairly simple method that can be readily incorporated into routine clinical practice.

Adolescent↗
PubMed1992

The influence of posture on the response to loop diuretics in patients with chronic cardiac failure is reduced by angiotensin converting enzyme inhibition.

The diuretic and natriuretic response to an intravenous dose of frusemide 40 mg was assessed in the erect and supine positions in 10 patients with cardiac failure who were being treated with enalapril 10 mg twice daily in addition to diuretics (Enalapril group) and in 10 patients with cardiac failure taking diuretics alone (Control group). Total 4 h diuresis in the erect position was 728 ml and in the supine position was 824 ml in the patients taking enalapril compared to 655 ml in the erect position and 1166 ml in the supine position in those patients taking diuretics alone. Total 4 h natriuresis in the erect positions was 78 mmol and in the supine position was 85 mmol in patients taking enalapril 10 mg twice daily but in those patients taking diuretics alone total 4 h natriuresis in the erect position was 67 mmol increasing to 120 mmol in the supine position. Measurements of plasma renin activity and plasma angiotensin II concentration confirmed effective converting enzyme inhibition, in the group of patients taking enalapril, but in those patients taking diuretics alone the erect position was associated with an increase in plasma renin activity, and plasma concentrations of angiotensin II and aldosterone. We conclude that the renin angiotensin system is a major factor in mediating the effect of posture on loop diuretic drugs.

Adult↗
PubMed1992

Lack of correlation between the acute haemodynamic response to intravenous captopril and plasma concentrations of angiotensin II in patients with chronic cardiac failure.

We have given a series of incremental intravenous injections of captopril to ten patients with chronic cardiac failure. Small doses of captopril produced significant changes in pulmonary artery end-diastolic pressure and right atrial pressure, up to a total cumulative dose of captopril of 2.5 mg, after which further injections had no significant effect. There were large changes in systemic vascular resistance and blood pressure up to a cumulative dose of captopril of 5.0 mg, after which the injection of larger doses caused no further significant changes. Small doses of intravenous captopril produced large increases in plasma renin activity and plasma angiotensin I concentrations up to a total cumulative dose of captopril of 1.25 mg, after which there were no significant further changes in either plasma renin activity or plasma angiotensin I concentration. However the plasma concentration of angiotensin II fell more slowly, no further change being recorded after a total cumulative dose of captopril of 10 mg. These results suggest that plasma renin activity is not the only determinant of plasma angiotensin II concentrations.

Aged↗
PubMed1992

Contrasting patterns of arterial and venous dilatation after intravenous captopril in patients with chronic cardiac failure and their relationship to plasma angiotensin II concentrations.

A 25 mg intravenous bolus injection of captopril caused an abrupt and rapid decrease in systemic vascular resistance (time to maximum effect 15 minutes), but a more gradual decrease in right atrial pressure (time to maximum effect 75 minutes) in 12 patients with chronic cardiac failure. Plasma angiotensin II concentrations fell significantly, reaching their lowest concentrations at 75 minutes after the injection of captopril, at which time systemic vascular resistance had begun to return toward control values. There was no correlation between the acute arteriodilator response and pretreatment plasma renin activity or plasma angiotensin II concentrations, or the decrease in plasma angiotensin II concentrations. There was a significant correlation between the decrease in plasma angiotensin II concentrations and the decrease in right atrial pressure (r = 0.67, p < 0.05). These findings suggest that in contrast to the venous response to intravenous captopril, the arterial response is not entirely dependent on a decrease in the circulating plasma angiotensin II concentration.

Aged↗
PubMed1992

The relationship between diuretic dose, and the haemodynamic response to captopril in patients with cardiac failure.

The effect of diuretic dose on the haemodynamic response to captopril was assessed in nine patients with chronic cardiac failure. Each patient was given an intravenous dose of captopril while maintained on (a) a low dose diuretic regime, and (b) a high dose diuretic regime. Activity of the renin angiotensin aldosterone system, as assessed by plasma concentrations of these hormones, was greater when patients were receiving the higher dose diuretic regime. The magnitude of haemodynamic response produced by intravenous captopril was greater when the patients were maintained on the high dose diuretic regime, although no significant correlation was found between resting plasma renin activity and resting plasma angiotensin II concentration and the change produced by captopril in any haemodynamic response on either diuretic regime. An increased dosage of loop diuretic potentiates the haemodynamic effects of captopril in patients with cardiac failure. Reduction of diuretic dose prior to introduction of captopril may protect against severe first dose hypotension.

Adult↗
PubMed1992

The Inoue balloon for dilatation of the tricuspid valve: a modified over-the-wire approach.

The Inoue balloon was used for dilatation of tricuspid stenosis in a 74 year old woman. The valve was reached by an over-the-wire approach with a 0.025 exchange length guide wire. The Inoue stylet would not reach the tricuspid orifice because the right atrium was so large. The Inoue balloon's special dilatation characteristics allowed good positioning at the tricuspid orifice. After dilatation to 27.5 mm, the pressure drop across the valve was reduced from 12 to 5 mm Hg. Further dilatation at 30 mm, however, created moderately severe tricuspid reflux without a further reduction of gradient. The Inoue balloon is suitable for dilatation of tricuspid stenosis but small increments in dilatation size may be required for optimal reduction in gradient without creating significant reflux.

Aged↗
PubMed1992

Percutaneous balloon dilatation of the mitral valve in patients who were unsuitable for surgical treatment.

OBJECTIVE: To assess the effects on haemodynamic function and symptoms of percutaneous balloon dilatation of mitral stenosis in patients unable to undergo surgical treatment because of associated medical/cardiac problems. DESIGN: A review of clinical outcome in 28 patients (of 108 undergoing balloon dilatation of the mitral valve) who were unsuitable for surgery. SETTING: A tertiary cardiac referral centre: some patients referred were from other cardiac centres in Scotland. PATIENTS: 28 patients judged by cardiac surgeons to be unsuitable for valve replacement or valvotomy because of respiratory disease (15 patients), nonmitral cardiac disease (6), multi-organ impairment (5), psychiatric problems (1) or dense intrathoracic adhesions (1). INTERVENTIONS: Percutaneous anterograde balloon dilatation of the mitral valve with polyethylene/polyvinyl balloons in 20 patients and the Inoue balloon in eight patients. MAIN OUTCOME MEASURES: Haemodynamic variables were measured before and immediately after mitral valve dilatation. Patient survival and symptom class (New York Heart Association) were followed for a year after the procedure. RESULTS: Dilatation at the mitral orifice was achieved in all cases. The mean (SD) pressure drop across the valve fell from 13.9 (5.3) to 5.6 (2.5) mm Hg, cardiac output rose from 3.18 (1.02) to 3.96 (2.5) l/min, and valve area increased from 0.78 (0.32) to 1.58 (0.56) cm2. The procedure was well tolerated by most patients, even those with metabolic/electrolyte disturbance, severe obstructive airways disease, myocardial impairment, and coronary disease. In three patients a small shunt developed at the atrial level: none developed severe mitral reflux. The two patients who required assisted ventilation died soon after the procedure and in one patient with severe coronary artery disease myocardial infarction developed and she died in cardiogenic shock. Early symptomatic improvement was reported by 23 of the 25 survivors, though the increase in exercise capacity was often limited by their non-mitral disease. At one year follow up a further 6 patients had died because of their additional disease: 15 continued to show symptomatic improvement. CONCLUSIONS: Percutaneous balloon dilatation of the mitral valve is a useful new option in patients who are too ill to undergo cardiac surgery; but longer term benefit can be limited by the associated disease.

Aged↗
PubMed1991

Elderly and younger patients selected to undergo coronary angiography.

OBJECTIVE: To establish and compare the characteristics of older (greater than or equal to 70 years) and younger patients with chest pain selected to undergo coronary angiography and by analysis of their subsequent management to assess the value of coronary angiography for older patients with chest pain. DESIGN: Retrospective analysis of clinical case notes and coronary angiography reports. SETTING: Cardiology department with referral population of one million in an Edinburgh hospital. PATIENTS: 134 consecutive patients with chest pain aged 70 years or over investigated by coronary angiography between 1978 and 1988; 134 randomly selected patients aged under 70 investigated over the same period. MAIN OUTCOME MEASURES: Clinical and angiographic features at time of angiography and management after angiography. RESULTS: Older patients represented a small, but increasing, proportion of those investigated. Older patients had more severe symptoms at the time of angiography, were taking more antianginal drugs, and had had their symptoms for longer than younger patients. At angiography more older patients had triple vessel coronary disease, left main stem stenosis, or left ventricular impairment. After angiography similar proportions of older and younger patients underwent coronary artery surgery, with more elderly patients requiring urgent operation; although operative mortality was higher for elderly patients, symptomatic benefit was similar to that in younger patients. CONCLUSIONS: Older patients with angina selected to undergo coronary angiography and subsequent coronary surgery have more severe symptoms and underlying cardiac disease. Earlier referral and investigation might yield a population with lower operative risk. Selection of patients for coronary angiography and coronary artery surgery should be based on the potential for benefit and should avoid "agism."

Adult↗
PubMed1991

A lack of effect of captopril on platelet aggregation in patients with congestive heart failure.

We have studied the acute and chronic effects of an ACE inhibitor (captopril) on platelet function and the renin-angiotensin system in patients with congestive heart failure. Plasma concentrations of angiotensin II fell significantly after a single dose of captopril (25 mg) and during long-term treatment with captopril (2 weeks, 75 mg/day). Plasma renin activity increased significantly after both the single and repeated doses. Captopril did not affect ADP-induced platelet aggregation or concentrations. It seems unlikely that circulating angiotensin II affects ADP-induced platelet aggregation in patients with congestive heart failure.

Angiotensin II↗
PubMed1991

Posture determines the nature of the interaction between angiotensin converting enzyme inhibitors and loop diuretics in patients with chronic cardiac failure.

The effects of inhibition of the renin angiotensin aldosterone system on the natriuretic and diuretic actions of an intravenous dose of frusemide 40 mg in patients with chronic cardiac failure maintained on oral diuretics were studied in the supine and erect positions. In the patients studied in the supine position the total 4 hour diuresis was decreased from 995 (92) ml to 668 (66) ml and the total 4 hour natriuresis fell from 105 (14) mmol to 67 (14) mmol following the administration of captopril. Creatinine clearance fell from 87 (8) ml/minute to 52 (15) ml/minute. In the patients studied in the erect position the total 4 hour diuresis was 596 (87) ml without captopril and 562 (83) ml with captopril. Total 4 hour natriuresis was 71 (13) mmol without captopril and 65 (9) mmol with captopril. Creatinine clearance was reduced by captopril from 82 (7) ml/minute to 47 (12) ml/minute. The reduction in the diuretic and natriuretic response to frusemide caused by captopril in the supine position is mediated through a fall in glomerular filtration rate. However, in the erect position, which is associated with even further increases in activity of the renin angiotensin aldosterone system, the reduction in diuresis and natriuresis that a fall in glomerular filtration rate would cause is offset by abolition of the rise in sodium retaining hormones, angiotensin II and aldosterone that mediate the antinatriuretic effect of the erect position.

Aged↗
PubMed1991

Mitral balloon valvuloplasty for patients aged over 70 years: an alternative to surgical treatment.

We report the results and one-year follow-up of 20 elderly patients (age range 70-82 years) with severe rheumatic mitral stenosis treated by mitral balloon valvuloplasty (MBV). All 20 were breathless at rest despite treatment with diuretics and digoxin. At cardiac catheterization, successful dilatation was achieved in 17 patients: mean transvalvular mitral gradient fell by 45%, mean cardiac output rose by 24% and mean valve area increased by 76%. There was no procedure-related mortality. At one month, 15 patients had experienced an improvement in symptoms of at least one New York Heart Association class and, at one year, ten had maintained this improvement. Three patients proceeded to mitral valve replacement because of a suboptimal symptomatic result. Mitral balloon valvuloplasty can be successfully performed with significant symptomatic benefit in frail elderly patients unfit for surgery and may also be offered to other selected elderly patients as an alternative to surgical treatment.

Age Factors↗