Biomedical subjects

Helen Rimington

Publications and source records attributed to Helen Rimington.

4 recordsLinked to original sources

PubMed2005

Exercise testing to stratify risk in aortic stenosis.

AIMS: The aims of this study were to assess the accuracy of exercise testing in predicting symptom onset within 12 months in patients with asymptomatic aortic stenosis and to establish the criteria that define a positive test. METHODS AND RESULTS: A total of 125 patients with aortic stenosis [effective orifice area (EOA) 0.9+/-0.2 cm2] were assessed by Specific Activity Scale (SAS) classification, transthoracic echocardiography, and treadmill exercise testing using the modified Bruce protocol. During follow-up, 36 patients (29%) developed spontaneous symptoms within 12 months. Of these, 26 (72%) had had symptoms revealed by exercise testing and 24 (67%) had severe stenosis (EOA < or = 0.8 cm2). Exercise-limiting symptoms were the only independent predictors of outcome at 12 months, and an abnormal blood pressure response or ST segment depression did not improve the accuracy of the exercise test. The positive predictive accuracy for exercise-induced symptoms was 57% in the whole population and 79% for patients aged <70 in SAS Class I. The negative predictive accuracy was 87% in the whole population and 86% in the subgroup. CONCLUSION: A significant proportion of patients with apparently asymptomatic aortic stenosis experience limiting symptoms on treadmill exercise testing. The subsequent development of spontaneous symptoms is strongly related to the severity of stenosis and to limiting symptoms on exercise testing, but less so to an abnormal blood pressure response or ST segment depression.

Aged↗

PubMed2004

Hemodynamic performance on exercise: comparison of a stentless and stented biological aortic valve replacement.

BACKGROUND AND AIM OF THE STUDY: Although stentless valves are expected to be hemodynamically superior to stented valves, the results of comparative trials have been inconsistent. The study aim was to compare hemodynamic function at rest and on exercise in 50 stentless and stented biological replacement aortic valves METHODS: Twenty-one patients with a Toronto stentless porcine valve and 29 with a Perimount stented bovine pericardial valve were exercised using a bicycle ergometer. Echocardiography was performed before, and during exercise testing. RESULTS: Patients with either valve type were exercised to a similar degree. Transaortic resistance was slightly lower in the Perimount compared with the Toronto at rest (p = 0.03) and at peak exercise (p = 0.04), and flow was higher in the Perimount at rest (p = 0.007), but not at peak exercise. There were no significant differences between the valve types in peak velocity, mean pressure difference or effective orifice area either at rest or on peak exercise. CONCLUSION: There were no clinically significant differences in hemodynamic function between the stented and stentless biological valves chosen for comparison either at rest or during bicycle exercise.

Aged↗

PubMed2004

Determinants of left ventricular mass in aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: There are many possible determinants of left ventricular (LV) mass, including the angiotensin-converting enzyme (ACE) genotype, which have rarely been compared in aortic stenosis (AS). The study aim was to investigate these determinants in patients with all grades of AS. METHODS: Transthoracic echocardiography and an analysis of ACE genotype was performed in 91 patients with aortic valve thickening and a peak aortic velocity >2.0 m/s. RESULTS: Univariate relationships were identified between LV mass index and effective orifice area (R = 0.22), and peak transaortic pressure difference (R = 0.36). LV mass index was similar for the ACE-II (152+/-37 g/m2), ACE-ID (145+/-46 g/m2) and ACE-DD (161+/-56 g/m2) genotypes. LV mass index was significantly greater in males (162+/-52 gm/m2) than in females (137+/-38 gm/m2; p = 0.014). The multivariate determinants varied according to the grade of AS: diastolic blood pressure (p = 0.028) in mild stenosis; peak transaortic pressure difference (p = 0.03) in moderate stenosis; and peak transaortic pressure difference (p <0.0001) and gender (p = 0.02) in severe stenosis. LV hypertrophy was present in 15 of 24 patients (63%) with mild AS, in 21 of 27 (78%) with moderate AS, and 32 of 40 (80%) with severe AS. CONCLUSION: LV hypertrophy is common, even in mild AS, when it is independently related only to the systemic blood pressure. This suggests that antihypertensive agents should be considered early in the natural history of AS.

Aged↗

PubMed2003

Determinants of symptoms and exercise capacity in aortic stenosis: a comparison of resting haemodynamics and valve compliance during dobutamine stress.

AIMS: Valve compliance might determine the onset of symptoms better than resting measures of aortic stenosis. This study compared valve compliance measured by dobutamine stress echocardiography with resting haemodynamic variables against the end-point of symptoms at low workload during exercise testing. METHODS AND RESULTS: Echocardiography was performed at rest and during each stage of a dobutamine stress test in 65 asymptomatic patients with moderate or severe aortic stenosis. Each patient also completed a modified Bruce treadmill exercise test. During dobutamine stress, peak transaortic velocity increased by 1.0 (0.4) m/s and effective orifice area by 0.25 (0.22) cm(2). Valve compliance was 0.23 (0.10) cm(2)/100ml.s(-1), and was independent of baseline effective orifice area. In the 19 patients limited by symptoms on exercise testing, valve compliance was significantly lower (0.19 (0.09) cm(2)/100ml.s(-1)) than in those who remained asymptomatic (0.25 (0.10) cm(2)/100ml.s(-1), p=0.03). Effective orifice area at peak stress was also lower (1.0 (0.3) vs 1.2 (0.4) cm(2), p=0.03), but there were no significant differences in resting measures of effective orifice area, transaortic velocity, or mean pressure drop. CONCLUSIONS: Effective orifice area is flow-dependent in patients with moderate and severe aortic stenosis with preserved left ventricular function. Exertional symptoms are better predicted by compliance than resting effective orifice area, mean pressure drop or peak transaortic velocity.

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