Biomedical subjects

Malcolm E Legget

Publications and source records attributed to Malcolm E Legget.

7 recordsLinked to original sources

PubMed2006

Longitudinal left ventricular contractile dysfunction after exercise in aortic stenosis.

OBJECTIVE: To determine whether longitudinal left ventricular systolic function measured by Doppler tissue imaging (DTI) after exercise can identify early left ventricular dysfunction in asymptomatic patients with moderate-severe aortic stenosis. DESIGN: Case-control study. SETTING: Outpatient cardiology departments. PATIENTS: 20 patients with aortic stenosis, with or without equivocal symptoms, a peak aortic valve velocity > or =3 m/s, and left ventricular ejection fraction >50% and 15 aged-matched normal controls. INTERVENTIONS: Echocardiogram performed at rest and immediately after treadmill exercise. MAIN OUTCOME MEASURES: The peak systolic velocity of the lateral mitral annulus (S') by DTI at rest and immediately after exercise, exercise capacity, exercise systolic blood pressure and the plasma level of B-type natriuretic peptide (BNP). RESULTS: For patients with aortic stenosis, mean (SD) aortic valve area was 0.95 (0.3) cm(2). At rest, S' was similar for patients with aortic stenosis and controls, respectively (8.5 (1.5) vs 9.1 (1.8) cm/s, p = 0.15). However, after exercise, S' (12.2 (3.2) vs 17 (2.8) cm/s, p<0.001) and the increase in S' between rest and exercise (4 (3) vs 7.9 (1.5) cm/s, p<0.001) were lower in patients with aortic stenosis. In patients with aortic stenosis, a smaller increase in S' after exercise was associated with lower exercise capacity (r = 0.5, p = 0.02), a smaller increase in exercise systolic blood pressure (r = 0.6, p = 0.005) and higher plasma level of BNP (r = 0.66, p = 0.002). CONCLUSION: In asymptomatic patients with moderate-severe aortic stenosis a lower than normal increase in peak systolic mitral annular velocity after treadmill exercise is a marker of early left ventricular systolic dysfunction.

Aged↗

PubMed2005

Extra-aortic balloon counterpulsation: an intraoperative feasibility study.

BACKGROUND: Current methods of counterpulsation or ventricular assistance have significant vascular and limb complications. The aim of this study was to determine the safety and performance of a new method of non-blood-contacting counterpulsation using an inflatable cuff around the ascending aorta (extra-aortic balloon [EAB]). METHODS AND RESULTS: In 6 patients undergoing first time off-pump coronary bypass surgery via sternotomy, the EAB was secured around the ascending aorta and attached to a standard counterpulsation console. At baseline and with 1:2 and 1:1 augmentation, hemodynamic and echocardiographic parameters of ventricular function and coronary flow were measured. High-intensity transient signals were measured using transcutaneous Doppler over the right common carotid artery. No complications occurred. With EAB there was no significant change in heart rate or blood pressure and no increase in high-intensity transient signals. There was a 67% increase in diastolic coronary blood flow (mean left-main diastolic velocity time integral 15.3 cm unassisted versus 25.1 cm assisted, P<0.05). Measurements with transesophageal echocardiography at baseline and with 1:1 counterpulsation demonstrated a 6% reduction in end-diastolic area (P=NS), a 16% reduction in end-systolic area (P<0.01), a 31% reduction in left ventricular wall stress (P<0.05), and a 13% improvement in fractional area change (P<0.005). CONCLUSIONS: EAB counterpulsation augments coronary flow and reduces left ventricular afterload. Further testing is warranted to assess the use of the EAB for chronic non-blood-contacting support of the failing heart.

Adult↗

PubMed2005

Usefulness of serial measurement of N-terminal pro-brain natriuretic peptide plasma levels in asymptomatic patients with aortic stenosis to predict symptomatic deterioration.

In 29 initially asymptomatic patients with aortic stenosis followed for an average of 18 months, patients with a N-terminal pro-brain natriuretic peptide (NT-pro-BNP) level above the normal range at baseline were more likely to develop symptoms during follow-up compared with patients with NT-pro-BNP within normal limits. The average increase in NT-pro-BNP per year was greater for patients who developed symptoms compared with patients who remained asymptomatic. Aortic valve area, peak aortic velocity, and the ejection fraction were less reliable predictors of symptom onset. Measurement of NT-pro-BNP in addition to clinical assessment and echocardiography may allow more reliable follow-up and timing of valve replacement for aortic stenosis.

Aged↗

PubMed2004

Pointwise assessment of three-dimensional computer reconstruction of mitral leaflet surfaces from rotationally scanned echocardiograms in vitro.

Three-dimensional transesophageal echocardiography offers promise for improved understanding of mitral leaflet pathology, but it has not been validated quantitatively, nor has the minimum number of imaging planes for satisfactory reconstruction been determined with a rotational scanning geometry. This study assessed its accuracy in vitro by comparing, on a 1 x 1-mm grid, the surfaces of mitral leaflets derived from 5-degree rotational ultrasonic scans with those derived from laser scans of casts of the atrial side of the leaflets. Overall, the ultrasonically derived surface had a mean absolute deviation of 0.65 +/- 0.12 mm from the laser-derived surface. Using only alternate imaging planes (10-degree increments) made no significant difference in the overall distribution of deviations (P =.56), although the distributions on some individual specimens differed markedly. We conclude that 5-degree rotational scanning in vitro can reconstruct the mitral valve leaflets with sufficient accuracy and detail to render clinically important features.

Animals↗

PubMed2003

Effect of aortic valve replacement on c-reactive protein in nonrheumatic aortic stenosis.

Plasma levels of C-reactive protein were higher in 20 patients with bicuspid or trileaflet degenerative aortic stenosis than in 31 normal controls and in 19 patients with pure aortic regurgitation. C-reactive protein decreased from before to 6 months after aortic valve replacement for aortic stenosis. These observations suggest that aortic stenosis is an inflammatory disease.

Adult↗

PubMed2003

Associations between plasma natriuretic peptide levels, symptoms, and left ventricular function in patients with chronic aortic regurgitation.

In 40 patients with chronic moderate to severe aortic regurgitation, brain natriuretic peptide, N-brain natriuretic peptide, and atrial natriuretic peptide were higher in symptomatic patients compared with asymptomatic patients after adjustment for age, gender, and ejection fraction, but each natriuretic peptide correlated weakly with echocardiographic measures of left ventricular size and function. In patients with chronic aortic regurgitation, measurement of natriuretic peptide levels may provide information on left ventricular function in addition to echocardiography.

Adult↗

PubMed2003

Increased plasma natriuretic peptide levels reflect symptom onset in aortic stenosis.

BACKGROUND: The onset of symptoms is a critical point in the natural history of aortic stenosis and the cardinal indication for valve replacement. This study assessed the associations between natriuretic peptide levels, disease severity, and cardiac symptoms in aortic stenosis. METHODS AND RESULTS: Seventy-four patients with isolated aortic stenosis underwent independent assessment of symptoms, transthoracic echocardiography, and measurement of plasma levels of atrial natriuretic peptide, brain natriuretic peptide (BNP), and N-BNP. Natriuretic peptide levels were also measured in 100 clinically normal control subjects. The aortic valve area was smaller in symptomatic patients (n=45) than in asymptomatic patients (n=29; mean, 0.71+/-0.23 cm2 and 0.99+/-0.31 cm2, respectively; P<0.0001). Plasma natriuretic peptide levels were higher in symptomatic patients than in asymptomatic patients (for N-BNP: median, 112 versus 33 pmol/L; interquartile range, 70 to 193 versus 16 to 58 pmol/L, respectively; P=0.0002). After adjustment for age, sex, serum creatinine, aortic valve area, and left ventricular ejection fraction, N-BNP levels were 1.74 times higher (95% confidence interval, 1.12 to 2.69) for symptomatic than asymptomatic patients with aortic stenosis (P=0.014). Natriuretic peptide levels increased with the New York Heart Association class (for N-BNP median values were 13, 34, 105, and 202 pmol/L for normal control subjects, class I, class II, and class III/IV patients, respectively; interquartile ranges for the same patients were 8 to 21, 16 to 58, 57 to 159, and 87 to 394 pmol/L; P<0.0001). Similar associations were observed for BNP and atrial natriuretic peptide. CONCLUSIONS: Plasma natriuretic peptide levels are elevated in symptomatic patients with aortic stenosis. Measurement of natriuretic peptides may complement clinical and echocardiographic evaluation of patients with aortic stenosis.

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