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Biomedical subjects

M St John Sutton

Publications and source records attributed to M St John Sutton.

At least 19 recordsLinked to original sources
PubMed2006

Reverse remodelling in heart failure with cardiac resynchronisation therapy.

This review examines the use of cardiac resynchronisation therapy (CRT) for chronic, severe, systolic heart failure. Left ventricular (LV) remodelling is the final common pathway of systolic heart failure and portends a poor prognosis. It is characterised by progressive LV dilatation, deterioration of ventricular contractile function and distortion of LV cavity shape. The LV remodelling process is triggered by prolonged pressure or volume overload, loss of contracting myocytes from myocardial infarction, genetic abnormalities of contractile proteins or exposure to cardiotoxic agents. Current therapeutic strategies for systolic heart failure aim to slow or halt the remodelling process. "Reverse remodelling" is a relatively new concept, where progressive LV dilatation and deterioration in contractile function are not simply arrested, but partially reversed. Cardiac resynchronisation therapy is a novel and effective treatment for systolic heart failure, and is associated with reverse remodelling of the LV.

Cardiac Pacing, Artificial↗
PubMed2002

Differences between echocardiographic measurements of left ventricular dimensions and function by local investigators and a core laboratory in a 2-year follow-up study of patients with an acute myocardial infarction.

AIMS: To examine differences in measurements of left ventricular dimensions and function, and prognostic value between local investigators and a core laboratory in a multicentre serial echocardiographic study. METHODS AND RESULTS: Seven hundred and fifty-six patients with acute myocardial infarction and preserved left ventricular function were examined at baseline and after 3 months with measurements by the biplane Simpson's method, and followed prospectively from 3 to 24 months. At baseline and 3 months local investigators relative to the core laboratory measured lesser end-diastolic volume by 8 and 6 ml (P<0.001), end-systolic volume by 3 and 2 ml (P<0.01), and ejection fraction by 0.0 and 0.6% (P<0.01), respectively. Local investigators and the core laboratory measured an increase in left ventricular end-diastolic volume of 8.6 and 6.9 ml, and in left ventricular end-systolic volume of 5.2 and 4.3 ml, and a decrease in left ventricular ejection fraction of 0.6 and 0.0%. Using the Cox proportionate hazards model, the prognostic value for subsequent clinical endpoints was significant both for the 3-month values (P<0.05) and changes (P<0.005) measured by the core laboratory, but not by local investigators. CONCLUSION: Only measurements in the core laboratory had significant prognostic value for subsequent clinical endpoints. These results strongly support the use of a core laboratory in studies employing echocardiographic measurements.

Chi-Square Distribution↗
PubMed2001

Are changes in left ventricular volume as measured with the biplane Simpson's method predominantly related to changes in its area or long axis in the prognostic evaluation of remodelling following a myocardial infarction?

AIMS: Two-dimensional (2D) echocardiography has been widely applied to measure left ventricular volumes with the biplane Simpson's method in the assessment of left ventricular remodelling following an acute myocardial infarction. This volume formula is based upon tracings of endocardium and measurement of long axis on left ventricular images. In the present follow-up study of post-myocardial infarction patients we evaluated the prognostic impact of changes in left ventricular areas and geometry versus long axis to determine if only long-axis measurements may be used for prognostic purposes. METHODS AND RESULTS: Two-dimensional echocardiographic video recordings of the apical four-chamber and long-axis views were obtained in 756 patients 2--7 days and 3 months following an acute myocardial infarction. All videotapes were sent to a core laboratory and left ventricular volumes were measured with the biplane Simpson's method in end-diastole and end-systole. During the first 3 months 44 patients had suffered one of the following end-points and were excluded: cardiac death, recurrent myocardial infarction, heart failure or chronic arrhythmia. Over a period of 3--24 months 58 such end-points occurred. With the Cox proportional hazards model the increase in left ventricular systolic volume was the strongest predictor for such events (Chi-square 18.5, P<0.0001), followed by an increase in end-systolic area (Chi-square 17.0, P<0.0001) and end-systolic spherity index (Chi-square 8.74,P =0.003). The increase in end-systolic long axis had only a borderline predictive value (Chi-square 4.3, P=0.04). The change in long-axis shortening from end-diastole to end-systole had no significant predictive value at all. CONCLUSION: In the studied population changes in left ventricular area and geometry, but not in the long axis, were mainly related to cardiac morbidity. The proper assessment of changes in left ventricular dimensions should therefore be based upon tracings of the area and not on long axis measurements only.

Aged↗
PubMed2000

Frequency, risk factors, and clinical outcomes of left ventricular assist device-associated ventricular thrombus.

A retrospective, transesophageal study of 51 consecutive patients receiving a left ventricular (LV) assist device (AD) over a 2-year period showed that LVAD-associated LV thrombosis (16%) was predicted by acute myocardial infarction, atrial cannulation, and postimplantation bleeding, and was associated with a fourfold increased risk of stroke compared with patients without thrombosis. LV cannulation, when using short-term LVADs, may decrease the incidence of LV thrombosis, and early transition to Heartmate-LVAD support may improve outcome.

Aged↗
PubMed2000

Effects of acute hyperglycaemia on cardiac function: an echocardiographic study of monozygotic twins.

BACKGROUND: A major cause of morbidity in type I diabetes is congestive heart failure due predominantly to left ventricular diastolic dysfunction. The mechanism of diastolic dysfunction remains unknown and does not relate to blood pressure, microvascular complications and glycated haemoglobin. Hyperglycaemia is the hallmark of diabetes and is a potential determinant of left ventricular diastolic dysfunction. OBJECTIVE: To determine whether acute hyperglycaemia can induce changes in left ventricular diastolic function in normal subjects similar to those observed in insulin-dependent diabetes mellitus (IDDM). DESIGN: Cross-sectional study. SETTING: London teaching hospital. SUBJECTS: Sixteen twins from eight identical twin pairs discordant for IDDM (age 18-38 years, five male) were studied; none had a history or evidence of myocardial ischaemia, valvular or primary heart muscle disease, systemic hypertension or nephropathy. INTERVENTIONS: Non-diabetic twins underwent a hyperglycaemic clamp at 10 mmol/l. MAIN OUTCOME MEASURES: Doppler echocardiography was performed in basal condition in identical twin pairs discordant for IDDM and repeated in the non-diabetic twins during hyperglycaemia. Blood glucose, insulin and catecholamines were measured at baseline and during hyperglycaemia. RESULTS: Transmitral Doppler E/A velocity ratio was significantly lower in diabetic than non-diabetic twins at baseline (1.44 (0.38) vs. 1.51 (0.19), P<0.05). Glucose infusion in the non-diabetic twins resulted in an increase in their E/A ratio (1.51 (0.19) vs. 1.82 (0. 47), P<0.05) due to an increase in E velocity (68 (12) to 64.7 (10. 7), P<0.05) and a decrease in the peak A velocity (42.7 (3.85) to 38. 0 (4.1), P<0.05). No significant changes were observed in peak E velocity or isovolumic relaxation time in the non-diabetic twins between baseline and hyperglycaemia. CONCLUSIONS: The alterations in left ventricular diastolic function induced by acute hyperglycaemia and consequent increase in plasma catecholamines do not mimic those demonstrated in IDDM patients.

Adolescent↗
PubMed1999

Coronary artery aneurysms: A 25-patient study.

Coronary artery aneurysm is a rare disorder, characterized by abnormal dilatation of a localized portion or diffuse segments of the coronary artery. We studied clinical demographics, catheterization findings, and clinical outcomes in an Asian patient cohort with documented coronary artery aneurysms. Compared to a Caucasian adult population, our patient cohort had a lower incidence of coronary artery aneurysm (0.25% vs. 2.6%), and more patients with nonobstructive coronary artery aneurysms (70%); age, gender, and coronary distribution were comparable. The initial presentation of myocardial infarction occurred in five patients (5/17, 30%) with nonobstructive coronary artery aneurysms; however, none who were receiving preventive medications consisting of anticoagulant and antiplatelet agents subsequently developed myocardial infarction. We conclude that the incidence of coronary artery aneurysms with or without associated significant coronary stenosis seems to be lower in the Asian population. In contrast, the incidence of nonobstructive coronary artery aneurysms is considerably high and should not be thought of as a relatively benign disease entity if not treated with preventive medications. Rheumatoid arthritis-related vasculitis might be a cause of coronary artery aneurysm. Surgical intervention is based on the severity of coronary artery stenosis. The result of medical treatment has been compatible with long-term survival. Cathet. Cardiovasc. Intervent. 48:31-38, 1999.

Adult↗
PubMed1998

Quantitation of left ventricular volumes and ejection fraction in post-infarction patients from biplane and single plane two-dimensional echocardiograms. A prospective longitudinal study of 371 patients.

AIMS: To determine whether left ventricular volumes and ejection fractions calculated from single plane two-dimensional echocardiograms using the algorithm (0.85A2L) correlate with those calculated using the biplane Simpson's method, and whether small changes in volumes and ejection fraction occurring post-infarction could be detected from single-plane as well as from biplane two-dimensional echocardiograms. METHODS AND RESULTS: Serial two-dimensional echocardiograms were obtained in 371 patients from the DEFIANT II trial a mean of 2 days, 1 week and 6 months post-infarction. Single plane volumes from the apical four chamber and apical long axis correlated closely with biplane Simpson's left ventricular volumes. Both single-plane left ventricular volumes significantly over-estimated biplane Simpson's volumes. Biplane Simpson's ejection fractions were consistently slightly under-estimated from the single-plane images. Differences between biplane Simpson's and single-plane volumes increased independently with increasing left ventricular size and distortion. The small changes in left ventricular volumes and ejection fraction over time were as reliably detected from single plane as from biplane images. CONCLUSION: Single-plane left ventricular volumes over-estimate biplane Simpson's volumes and under-estimate ejection fraction, and these discrepancies are amplified in dilated hearts with abnormal shape.

Adult↗