Rainer Preuss

Myocardial Sympathetic Innervation in Patients with Symptomatic Coronary Artery Disease: Follow-up After 1 Year with Neurostimulation

In both diabetic and nondiabetic patients, there is a loose correlation between coronary flow reserve (CFR) and sympathetic innervation in viable myocardial segments. The loose correlation implies that sympathetic innervation may be preserved even with major impairment of myocardial blood supply. In some patients, denervation is due to repetitive episodes of ischemia in areas with severely reduced CFR. We investigated the long-term effect of reduced CFR on myocardial sympathetic innervation in diabetic and nondiabetic patients with spinal cord stimulation. Methods: We analyzed 23 patients (10 diabetic and 13 nondiabetic) with coronary artery disease and without known cardiac autonomic neuropathy. At baseline, we determined quantitative myocardial blood flow using 13N-ammonia PET, myocardial viability using 18F-FDG PET, and cardiac innervation using 11C-hydroxyephedrine (HED) PET. At the 1-y follow-up we measured CFR and 11C-HED retention. During follow-up, no cardiac intervention was performed and no myocardial infarction occurred. In all patients, spinal cord stimulation was performed for relief of angina. Results: There was no significant difference in segmental 11C-HED retention between baseline and follow-up in the whole patient group. In diabetic patients, as well as in segments with severely reduced CFR (<1.5), 11C-HED retention showed a small but significant decrease (P < 0.05). Linear regression of segmental 11C-HED retention between baseline and follow-up was high (r2 = 0.81), confirming good reproducibility of the investigation on the one hand and little change in regional sympathetic innervation on the other hand. Conclusion: In patients with stable chronic coronary artery disease, sympathetic innervation of the myocardium is almost unchanged in both diabetic and nondiabetic patients in a 1-y follow-up. In myocardial segments with severely altered blood supply, a small but significant decrease in 11C-HED retention most probably reflects ischemic neuronal damage. The prognostic relevance of sympathetic denervation in viable myocardium still has to be determined.

Respiratory resistance of patients during cardiac stress testing with adenosine: Is dyspnea a sign of bronchospasm?

BackgroundA denosine is widely used for stress-testing in myocardial perfusion imaging. During adenosine infusion, dyspnea is one of the main complaints of patients. The aim of this study was to determine whether dyspnea during adenosine infusion is caused by bronchospasm.MethodsFifty-four patients were enrolled in the study. Seven of these 54 suffered from mild chronic obstructive pulmonary disease (COPD). We continuously measured respiratory resistance (Rrs), using impulse oscillometry. Respiratory resistance was measured before, during, and after a continuous infusion of 140 μg/kg/min adenosine.ResultsSixty-seven percent of patients suffered from dysnea during adenosine infusion. In patients with mild COPD, Rrs was higher compared with other patients (0.48 vs 0.27 kPa/L/s, P<.05). Neither patients with COPD nor those without COPD exhibited a significant increase in Rrs during adenosine infusion. The Rrs of patients with dyspnea was insignificantly lower compared with patients without dyspnea(P=.469).ConclusionsDyspnea as a side effect of adenosine infusion is not correlated with impaired respiratory resistance in nonasthmatic pattents and in patients with mild COPD. Thus bronchospasm is ruled out as cause of this clinical symptom. Despite the small number of COPD patients enrolled in the study, adenosine infusion might be possible in patients with mild COPD.

Influence of preoperative MDCT analysis by a dedicated software on aortic insufficiency and outcome in patients after TAVI

Background: Multidetector computed tomography (MDCT) has been increasingly employed for valve sizing before TAVI as it enables a 3-dimensional analysis of the aortic annulus. Therefore, the aim of this study was to retrospectively analyze if image analysis has an influence on outcomes of patients undergoing TAVI. Methods: A total of 186 consecutive pre-TAVI-MDCTs of patients treated in 2010 and 2011 at our institution when the minimum/maximum diameter of the aortic annulus as determined by MDCT was used for valve sizing, were retrospectively analyzed with the image analysis software (3-mensio Medical Imaging) in a blinded fashion. Parameters used for calculation of the aortic annulus size included annulus area, diameter and perimeter. Valve sizes were determined as recommended by the respective manufacturer based on these parameters. Results: Patients either received the Edwards Sapien (n = 91), the Medtronic Corevalve (n = 84) or the Medtronic Engager (n = 11). In 130 patients (69.9%/Group A) image analysis recommended the same valve size that was actually implanted. However, in 29 patients (15.6%/Group B) image analysis revealed a larger valve size and in 27 patients (14.5%/Group C) a smaller size was suggested. Patients of group B showed a seven-fold higher rate of aortic regurgitation (AR)≥2 (n = 6/29) compared to group A (n = 4/130;p = 0.001) whereas group C did not show a higher incidence of conduction disorders (p = 0.5). Interestingly, there was no difference in 30 day mortality (4.6%(A), 3.4%(B), 7.4%(C) p = 0.76) and 1-year mortality between all three groups (27.5%(A), 17.2%(B), 30.4%(C); p = 0.21). Conclusion: Retrospective image analysis of pre-TAVI-MDCTs by a dedicated software revealed a different valve size in about one third of the patient cohort. Patients with an undersized valve had a seven fold higher risk for moderate AR but this did not translate into a reduced 1 year survival of the respective patients.