Biomedical subjects
Publications and source records attributed to Udo Sechtem.
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CMR is a rapidly developing new modality with applications in clinical cardiology for detection and assessment of myocardial ischemia and viability. CMR perfusion results for the detection of ischemia in comparison with stress echocardiography and scintigraphic techniques are reasonable, but all the studies reported to date have been conduced in selected patients. Larger studies in patient populations reflecting a broader spectrum of disease are necessary before perfusion CMR can be envisaged as a clinically reliable and robust diagnostic tool. Other CMR techniques provide a variety of novel methods of obtaining information on postischemic viability. Signs of viability that can be observed by CMR are the absence of late gadolinium-based contrast enhancement in a myocardial region involved in a recent infarct, any sign of wall thickening at rest (which is detectable with high accuracy by CMR), wall thickening after stimulation by low-dose dobutamine, and preserved wall thickness. Conversely, myocardial necrosis is characterized by signal enhancement of the infarct area after injection of Gd-DTPA, reduced wall thickness in chronic infarcts, and absence of a contractile reserve during dobutamine stimulation. Dobutamine CMR and late enhancement contrast-enhanced CMR predict contractile improvement after revascularization.
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BACKGROUND: Syncope is a well-recognized symptom of acute aortic dissection, often indicating the development of dangerous complications such as cardiac tamponade. SUBJECTS AND METHODS: We identified consecutive patients with acute aortic dissection at 18 referral centers in six countries. Data on key clinical findings and outcomes were collected via extensive questionnaires. Multiple logistic regression models were used to determine the association between syncope and in-hospital mortality, adjusting for demographic characteristics, dissection type, comorbid conditions, and complications (e.g., cardiac tamponade). RESULTS: Syncope was reported in 96 (13%) of 728 patients. Patients with syncope were more likely to die in the hospital (34% [n = 33 deaths]) than were those without syncope (23% [144/632], P = 0.01). They were also more likely to have cardiac tamponade (28% [n = 27] vs. 8% [n = 49], P <0.001), stroke (18% [n = 17] vs. 4% [n = 27], P <0.001), and other neurologic deficits (25% [n = 24] vs. 14% [n = 88], P = 0.005). After multivariate adjustment, clinical factors independently associated with the occurrence of syncope included a proximal dissection (odds ratio [OR] = 5.5; 95% confidence interval [CI]: 2.5 to 12; P <0.001), cardiac tamponade (OR = 3.1; 95% CI: 1.7 to 5.4; P <0.001), and stroke (OR = 3.5; 95% CI: 1.7 to 7.2; P = 0.001). There was a significant association between in-hospital death and syncope after adjustment for demographic characteristics alone (OR = 2.0; 95% CI: 1.2 to 3.5; P = 0.01), but not after adjustment for dissection type, comorbid conditions, and complications. CONCLUSION: Patients with dissections complicated by cardiac tamponade or stroke are significantly more likely to present with syncope. If these complications are excluded, syncope alone does not appear to increase the risk of death independently.
BACKGROUND: Chronobiological rhythms have been shown to influence the occurrence of a variety of cardiovascular disorders. However, the effects of the time of the day, the day of the week, or monthly/seasonal changes on acute aortic dissection (AAD) have not been well studied. METHODS AND RESULTS: Accordingly, we evaluated 957 patients enrolled in the International Registry of Acute Aortic Dissection (IRAD) between 1996 and 2000 (mean age 62+/-14 years, type A 61%). A chi2 test for goodness of fit and partial Fourier analysis were used to evaluate nonuniformity and rhythmicity of AAD during circadian, weekly, and monthly periods. A significantly higher frequency of AAD occurred from 6:00 AM to 12:00 noon compared with other time periods (12:00 noon to 6:00 PM, 6:00 PM to 12:00 midnight, and 12:00 midnight to 6:00 AM; P<0.001 by chi2 test). Fourier analysis showed a highly significant circadian variation (P<0.001) with a peak between 8:00 AM and 9:00 AM. Although no significant variation was found for the day of the week, the frequency of AAD was significantly higher during winter (P=0.008 versus other seasons by chi2 test). Fourier analysis confirmed this monthly variation with a peak in January (P<0.001). Subgroup analysis identified a significant association for all subgroups with circadian rhythmicity. However, seasonal/monthly variations were observed only among patients aged <70 years, those with type B AAD, and those without hypertension or diabetes. CONCLUSIONS: Similar to other cardiovascular conditions, AAD exhibits significant circadian and seasonal/monthly variations. Our findings may have important implications for the prevention of AAD by tailoring treatment strategies to ensure maximal benefits during the vulnerable periods.