Left Ventricular Responses to Acute Changes in Late Systolic Pressure Augmentation in Older Adults.
Changes in the cardiovascular system with age may predispose older persons to development of heart failure with preserved ejection fraction. Vascular stiffening, aortic pressure augmentation, and ventricular-vascular coupling have been implicated. We explored the potential for acute reductions in late systolic pressure augmentation to impact left ventricular relaxation in older persons without heart failure.METHODS
Sixteen older persons free of known cardiovascular disease with the exception of hypertension had noninvasive tonometry and cardiac ultrasound to evaluate central augmentation index (AI) and diastolic function at baseline and after randomized, blinded administration of intravenous B-type natriuretic peptide (BNP) and hydralazine in a crossover design.RESULTSAI was significantly reduced after BNP (11.4±8.9 to -0.2±14.7%; P = 0.02) and nonsignificantly reduced after hydralazine (14.7±8.4% to 11.5±8.8%; P = 0.39). With decreased AI during BNP, a trend toward worsened myocardial relaxation by tissue Doppler imaging occurred (E' velocity pre- and post-BNP: 10.0±2.5 and 8.8±2.0cm/s, respectively; P = 0.06). There was a significant fall in stroke volume with BNP (68.5±18.3 to 60.9±18.1ml; P = 0.02), suggesting that changes in preload overwhelmed effects of afterload reduction on ventricular performance. With hydralazine, neither relaxation nor stroke volume changed.CONCLUSIONS
Acute changes in late systolic aortic pressure augmentation do not necessarily lead to improved systolic or diastolic function in older people. Preload may be a more important determinant of cardiac performance than afterload in older people with compensated ventricular function. The potential for changes in preload to impair rather than enhance left ventricular systolic and diastolic function in older people warrants further study.CLINICAL TRIALS REGISTRATIONThis study is registered at clinicaltrials.gov as NCT00204984.
- SourceAvailable from: ahajournals.orgCirculation 08/1980; 62(1):105-16. · 14.95 Impact Factor
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ABSTRACT: Serum creatinine concentration is widely used as an index of renal function, but this concentration is affected by factors other than glomerular filtration rate (GFR). To develop an equation to predict GFR from serum creatinine concentration and other factors. Cross-sectional study of GFR, creatinine clearance, serum creatinine concentration, and demographic and clinical characteristics in patients with chronic renal disease. 1628 patients enrolled in the baseline period of the Modification of Diet in Renal Disease (MDRD) Study, of whom 1070 were randomly selected as the training sample; the remaining 558 patients constituted the validation sample. The prediction equation was developed by stepwise regression applied to the training sample. The equation was then tested and compared with other prediction equations in the validation sample. To simplify prediction of GFR, the equation included only demographic and serum variables. Independent factors associated with a lower GFR included a higher serum creatinine concentration, older age, female sex, nonblack ethnicity, higher serum urea nitrogen levels, and lower serum albumin levels (P < 0.001 for all factors). The multiple regression model explained 90.3% of the variance in the logarithm of GFR in the validation sample. Measured creatinine clearance overestimated GFR by 19%, and creatinine clearance predicted by the Cockcroft-Gault formula overestimated GFR by 16%. After adjustment for this overestimation, the percentage of variance of the logarithm of GFR predicted by measured creatinine clearance or the Cockcroft-Gault formula was 86.6% and 84.2%, respectively. The equation developed from the MDRD Study provided a more accurate estimate of GFR in our study group than measured creatinine clearance or other commonly used equations.Annals of internal medicine 04/1999; 130(6):461-70. · 16.10 Impact Factor
- Journal of the American College of Cardiology 05/2010; 55(19):2183; author reply 2184. · 15.34 Impact Factor