Use of Arterial Transfer Functions for the Derivation of Central Aortic Waveform Characteristics in Subjects With Type 2 Diabetes and Cardiovascular Disease

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Abstract
OBJECTIVE—Optimal blood pressure control in subjects with diabetes reduces cardiovascular complications. There is theoretical benefit in the assessment of central aortic waveforms including the augmentation index, which is taken as a putative index of stiffness. Transfer functions may be used to reconstruct aortic from radial pressure waveforms; however, a single generalized transfer function may not be appropriate for all patients. We aimed to evaluate the technique in subjects with diabetes. RESEARCH DESIGN AND METHODS—Simultaneous invasive central aortic and noninvasive radial waveforms were acquired in 19 subjects with type 2 diabetes, and a diabetes-specific transfer function was derived. Similar data were acquired from 38 age- and sex-matched subjects without diabetes. Central waveforms were reconstructed using a generalized transfer function in all patients and the diabetes-specific transfer function in individuals with diabetes. RESULTS—There was no difference between groups in measured central pressures. The error in generalized transfer function-derived systolic pressure was greater in individuals with diabetes (6 ± 7 mmHg) (mean ± SD) than without diabetes (2 ± 8 mmHg) (P < 0.05). Errors in other parameters were no different. The diabetes-specific transfer function reduced the error in derived systolic pressure to 0 ± 7 mmHg in individuals with diabetes—no different than that with the generalized transfer function in individuals without diabetes. The central augmentation index reconstructed by either transfer function was unrelated to that directly measured. CONCLUSIONS—A generalized transfer function is inappropriate for the derivation of central waveforms in subjects with type 2 diabetes. Errors in subjects with diabetes might be reduced with a diabetes-specific transfer function.