The diastolic flow velocity-pressure gradient relation and dpv50 to assess the hemodynamic significance of coronary stenoses.

To evaluate the hemodynamic impact of coronary stenoses, the fractional (FFR) or coronary flow velocity reserve (CFVR) usually is measured. The combined measurement of instantaneous flow velocity and pressure gradient (v-dp relation) is rarely used in humans. We derived from the v-dp relation a new index, dp(v50) (pressure gradient at flow velocity of 50 cm/s), and compared the diagnostic performance of dp(v50), CFVR, and FFR. Before coronary angiography was performed, patients underwent noninvasive stress testing. In all coronary vessels with an intermediate or severe stenosis, the flow velocity, aortic, and distal coronary pressure were measured simultaneously with a Doppler and pressure guidewire after induction of hyperemia. After regression analysis of all middiastolic flow velocity and pressure gradient data, the dp(v50) was calculated. With the use of the results of noninvasive stress testing, the dp(v50) cutoff value was established at 22.4 mmHg. In 77 patients, 124 coronary vessels with a mean 39% (SD 19) diameter stenosis were analyzed. In 43 stenoses, ischemia was detected. We found a sensitivity, specificity, and accuracy of 56%, 86%, and 76% for CFVR; 77%, 99%, and 91% for FFR; and 95%, 95%, and 95% for dp(v50). To establish that dp(v50) is not dependent on maximal hyperemia, dp(v50) was recalculated after omission of the highest quartile of flow velocity data, showing a difference of 3%. We found that dp(v50) provided the highest sensitivity and accuracy compared with FFR and CFVR in the assessment of coronary stenoses. In contrast to CFVR and FFR, assessment of dp(v50) is not dependent on maximal hyperemia.

Noninvasive mapping of left ventricular electromechanical asynchrony by three-dimensional echocardiography and semi-automatic contour detection.

A system for analyzing left ventricular (LV) electromechanical asynchrony based on transesophageal 3-dimensional echocardiography (3-DE) and semi-automatic endocardial contour detection is described. Eighteen consecutive patients underwent 3-DE. Using TomTec 4DLV software, a 3-dimensional endocardial surface was reconstructed throughout the cardiac cycle. Matlab software generated color-coded polar maps, displaying regional LV displacement and its timing. At the segmental level, Bland-Altmann assessment showed intraobserver variability of LV displacement of 0.1 +/- 3.0 mm and timing of -5.6 +/- 160 ms (bias +/- 2 SD) for all segments and -1.6 +/- 94 ms for the nonapical segments. The combination of 3-DE and semi-automatic contour detection is feasible and provides unique information for assessing regional LV endocardial displacement and electromechanical asynchrony.

Admission blood glucose level as risk indicator of death after myocardial infarction in patients with and without diabetes mellitus.

BACKGROUND: High admission blood glucose levels after acute myocardial infarction (AMI) are common and associated with an increased risk of death in subjects with and without known diabetes. Recent data indicate a high prevalence of abnormal glucose metabolism in patients with unknown diabetes at the time of AMI. We investigated the predictive value of admission blood glucose levels after AMI for long-term prognosis in patients with and without previously diagnosed diabetes mellitus, particularly in those with unknown diabetes but with blood glucose levels in the diabetic range. METHODS: In a retrospective study with prospective follow-up, 846 patients (737 without and 109 with known diabetes) were eligible for follow-up during a median of 50 months (range, 0-93 months). RESULTS: During follow-up, 208 nondiabetic patients (28.2%) and 47 diabetic patients (43.1%) died (P =.002). An increase of 18 mg/dL (1 mmol/L) in glucose level was associated with a 4% increase of mortality risk in nondiabetic patients and 5% in diabetic patients (both P<.05). Of the 737 previously nondiabetic subjects, 101 had admission blood glucose levels of 200 mg/dL (11.1 mmol/L) or more, and mortality in these patients was comparable to that in patients who had established diabetes (42.6% vs 43.1%). CONCLUSIONS: Admission blood glucose level after AMI is an independent predictor of long-term mortality in patients with and without known diabetes. Subjects with unknown diabetes and admission glucose levels of 200 mg/dL (11.1 mmol/L) or more after AMI have mortality rates comparable to those of subjects with established diabetes. Admission blood glucose level may serve to identify subjects at high long-term mortality risk, in particular among those with unknown diabetes.

The diastolic flow-pressure gradient relation in coronary stenoses in humans.

OBJECTIVES: We assessed the feasibility and reproducibility of the instantaneous diastolic coronary flow velocity-pressure gradient relation to characterize different degrees of coronary stenoses. BACKGROUND: Assessment of the hemodynamic significance of coronary stenoses can be difficult. Using sensor-tipped guidewires, various physiologic indexes can be determined in the catheterization laboratory. Each of the current methods, however, has limitations. METHODS: After positioning a Doppler flow wire and a pressure wire distal of a coronary stenosis, the flow velocity signals and the proximal and distal pressure were sampled simultaneously, at baseline and after intracoronary administration of adenosine. The instantaneous diastolic flow velocity and pressure gradient of single cardiac cycles at baseline, at maximal and intermediate hyperemia were plotted. Data were fitted with a regression line using the equation: Delta P = 0 +kv+Sv(2). Measurements were performed in 11 normal coronary arteries, 20 intermediate stenoses and in 7 severe stenoses before and after percutaneous transluminal coronary angioplasty plus stenting. RESULTS: We found significant differences between normal coronary arteries, intermediate and severe stenoses. Percutaneous transluminal coronary angioplasty nearly normalized the highly abnormal flow-pressure gradient relation in the severe stenoses. A high degree of reproducibility was observed. In 3% of the measurements, analysis was not possible due to the occurrence of pressure drift or bad flow velocity signals. CONCLUSIONS: It is feasible to assess the diastolic flow velocity-pressure gradient relation over a wide range of stenoses. It characterizes the hemodynamics of epicardial coronary stenoses and allows discrimination between normal coronary arteries, intermediate and severe stenoses.