Ragnar Danielsen

Subclinical left ventricular abnormalities in young subjects with long-term type 1 diabetes mellitus detected by digitized m-mode echocardiography

Noninvasive studies in patients with type 1 diabetes mellitus suggest subclinical left ventricular (LV) impairment, but the studies differ with regard to methods, patient selection and results. Thus, digitized M-mode echocardiograms were recorded in 24 persons younger than 50 years with long-term (more than 12 years) type 1 diabetes but without overt heart disease and in 28 control subjects. To improve accuracy, measurements were adjusted for body surface area, LV size and the influence of heart rate, as appropriate. Diabetics had a higher heart rate and systolic and diastolic blood pressure than control subjects. LV end-diastolic and stroke dimensions were smaller, duration of systole longer and preejection period/LV ejection time ratio higher than in control subjects, whereas fractional shortening and peak shortening rate were similar. In diabetics, diastole was shorter, peak filling rate was lower and the rapid filling period was prolonged, while percent filling during the rapid filling period and atrial contribution to filling were higher. Thus, in a well defined study population of relatively young persons with long-term type 1 diabetes, subclinical LV systolic and diastolic dysfunction were found. The diastolic abnormalities suggest reduced LV compliance, while those in systole may be secondary to an increased afterload or decreased myocardial contractility.

Factors affecting Doppler echocardiographic valve area assessment in aortic stenosis

Doppler echocardiographic assessment of the aortic valve area (AVA) using the continuity equation was performed before cardiac catheterization in 100 patients with suspected aortic stenosis. Doppler echocardiographic AVA correlated closely with AVA calculated by the Gorlin equation at catheterization (r = 0.96). However, Doppler echocardiography slightly but systematically underestimated the AVA (p less than 0.001) and did so most markedly in patients with mild stenosis (greater than 1.0 cm2). In multivariate analysis, the difference in AVA by the 2 techniques was positively associated with left ventricular (LV) stroke volume and inversely with the difference between mean catheterization and Doppler gradients, LV ejection fraction and LV outflow tract velocity. Furthermore, the AVA difference also was related to gender, being larger in women. Thus, overall Doppler echocardiography reliably assesses AVA, but the usefulness of the method is somewhat reduced by its underestimation of AVA in mild stenosis. This drawback, however, is usually overcome by taking patients symptoms into account. Furthermore, lacking a gold standard, this underestimation need not imply errors of the Doppler echocardiographic method alone, but also may reflect known inaccuracies of the catheterization technique.

Importance of adjusting left ventricular diastolic peak filling rate for heart rate.

Abstract Recently, the importance of left ventricular (LV) diastolic function for cardiac performance in various diseases has been reported in studies using both digitized M-mode echocardiography 1,2 and radionuclide ventriculography. 3 However, the potential influence of physiologic factors, including heart rate (HR), loading conditions and LV systolic function, on diastolic function variables is currently debated. 4–6 Although Bianco et al 5 found the LV peak diastolic filling rate to be positively related to HR when subjects were studied at rest, 5 others found contrary results. 4,6 Atrial pacing 7 and exercise studies 5 do suggest such an association. Further, a positive relation between LV systolic function and diastolic relaxation has both been reported 4,5 and refuted. 6 In addition, both preload and afterload may influence LV diastolic properties. 8 We used digitized M-mode echocardiography to evaluate the changes in peak diastolic filling rate during moderate exercise in normal subjects and the physiologic factors influencing it.

Physiological effects of short-term training after myocardial infarction

The effects of a period of 4 weeks training on treadmill exercise performance were evaluated in 27 patients, mean +/- SD age 55 +/- 7 years, who had previously suffered a myocardial infarction (17 Q-wave) 3-24 months (mean 11 +/- 8). To ensure comparability of exercise levels only patients who obtained their predicted maximal heart rate in the initial test were included. All trained 3-4 hours daily 5 days a week at an average maximal intensity of 85% of their initial peak heart rate. They performed 2 maximal exercise tests before and 1 after the training course. Maximal oxygen consumption was 28.1 +/- 5.3 and 28.8 +/- 6.5 ml/kg/minute (NS) before, and increased by 16% to 33.4 +/- 7.2 after training (P less than 0.01). Treadmill exercise distance was 510 +/- 153 and 559 +/- 163 meters (10% increase, P less than 0.01) before, and increased by 14% to 638 +/- 156 after (P less than 0.01). Heart rate, ratio of respiratory gas exchange, and breathing frequency remained unchanged in all three tests at maximal exercise, but were significantly lower at identical submaximal levels after training, while the respiratory tidal volume increased. Resting heart rate decreased by 12% after (P less than 0.01). Thus, aerobic exercise performance is improved by short-term training after myocardial infarction. By the longitudinal design of the study, and the maximal initial exercise test, this physiological improvement can be differentiated from that of increased motivation, and of increased treadmill exercise distance due to improved exercise technique.

Echocardiographic decision-making for replacement surgery in mitral valve prolapse

The clinical usefulness of M-mode echocardiography for predicting severe mitral regurgitation (MR) requiring valve replacement was assessed in 16 men and 10 women with mitral valve prolapse (MVP) as sole primary cardiac disorder. From left ventricular (LV) angiography, MR was classified as none to moderate (8 cases, group A) or severe (18 cases, group B). At echocardiography, increased LV end-diastolic and end-systolic and left atrial (LA) dimensions, corrected for body-surface area, distinguished group B from group A, with the best validities for LA and LV end-diastolic values. The mean echocardiographic LV fractional shortening and ejection fraction (EF) and the angiographic EF were similar in both groups. Echocardiographic and angiocardiographic LV EF correlated poorly, the former usually overestimating the latter. LV end-diastolic and mean pulmonary capillary wedge pressures were highest in group B, and the latter correlated with echocardiographic LA size. Mitral valve replacement was subsequently performed on 15 of the 18 group B patients. M-mode echocardiography is a valuable adjuvant to clinical assessment of MVP for predicting MR severity and for time-planning of cardiac catheterization or mitral valve surgery.