Dose-dependent disintegration of human endothelial monolayers by contrast echocardiography

Biological effects on endothelium induced by contrast ultrasound (US) may be relevant for transferring drugs into the tissue. An in vitro tissue-mimicking phantom was developed to simulate clinical precordial echocardiography of three modalities (two-dimensional (2DE), pulsed wave (PW), and Power Doppler echocardiography) with gradual increases of acoustic output (mechanical index (MI) 0.0-1.6 and thermal index soft tissue (TIS) 0.0-1.3, respectively; transmit-frequency 1.8 MHz in second harmonic mode (SHI) by 2DE, 1.8 MHz for PW-Doppler, and 3.2 MHz for Power Doppler) as well as contrast agent (CA) concentrations (0.002-4 mg/mL Levovist). Disintegration of the endothelial monolayer was quantitatively analyzed by counting intercellular gaps in light microscopy. No gaps were observed in CA application without sonication. Only few gaps appeared at sonication without CA application in 2DE at MI=1.6 and in PW- and Power Doppler at TIS > or =0.4 and MI > or =0.4. The number of gaps increased significantly with the gradual increase of US output and to a comparably lesser but also significant extent with CA concentrations. Diagnostic contrast echocardiography may induce endothelial disintegrations dependent on US output as well as on CA concentrations. This aspect might be helpful in further in vivo series on local drug delivery.

[Calculation of the incidence of primary care visits due to acute respiratory infections]

Data collected by the German influenza sentinel of the Working Group on Influenza (AGI) do not allow calculation of the incidence of primary care visits due to acute respiratory infections (ARI). Because patients do not have to register with a particular general practitioner, the population covered by primary care physicians is unknown. Until now the incidence of primary care visits due to ARI is estimated indirectly by extrapolating the sentinel sample of physicians to the total number of primary care physicians caring for the total population. However, distortions of the estimated incidence occur in weeks with public holidays (particularly around Christmas and New Year) and when many physicians close their practice simultaneously because of vacation. We have attempted to quantify the shortage of medical services and established thresholds to correct for situations where service by medical providers is extraordinarily reduced. The suggested method avoids distortions to a large extent and makes interpretation of data during those critical periods possible. A second subject of the paper is the validation of the estimated ARI incidence in primary care practices by comparing the data to other sources such as sick leave statistics of health insurance as well as ICD-based data from a primary care network. We found that the estimated ARI incidence in primary care practices was in line with data from other sources and appears plausible.

Progression of aortic valve calcification: association with coronary atherosclerosis and cardiovascular risk factors

BACKGROUND

Recent studies demonstrated an influence of atherosclerotic risk factors on the progression of aortic valve stenosis. The extent of aortic valve calcification (AVC) was also found to be a strong predictor of stenosis progression. We investigated the influence of the LDL cholesterol level (LDL), other standard cardiovascular risk factors, and the extent of coronary calcification (CC) on the progression of AVC quantified by electron beam tomography (EBT).

METHODS AND RESULTS

In 104 patients (64.7+/-8 years, 89 male) with an EBT scan positive for AVC, CC and AVC were quantified using a volumetric score. EBT was repeated at a mean interval of 15 months (10 to 36 months), and the progression of AVC and CC was determined. Patients were divided into 2 groups according to LDL: group 1, LDL</=3.36 mmol/L (130 mg/dL), 57 patients; group 2, LDL>3.36 mmol/L (130 mg/dL), 47 patients. Mean values for CC were 546+/-932 mm(3) in scan 1 and 665+/-1085 mm(3) in scan 2 for AVC 324+/-796 mm(3) and 404+/-1076 mm(3), respectively. The mean progression of CC was 27+/-37% (group 1, 16+/-22%; group 2, 39+/-46%, P</=0.001) and of AVC was 25+/-38% (group 1, 9+/-22%; group 2, 43+/-44%, P</=0.001).

CONCLUSIONS

Quantification of AVC by EBT permits new insights into the progression of aortic valve sclerosis. We observed a strong influence of LDL cholesterol level on the progression of AVC and CC, suggesting that lipid-lowering therapy may decrease the progression of aortic valve calcification.