Estimation of left ventricular volume from apical orthogonal 2-D echocardiograma

In 42 consecutive patients undergoing biplane left ventricular cine-angiography, left ventricular volumes were first determined ultrasonically using a phased array transducer. To this end, two orthogonal apical long axis views were recorded one illustrating all four chambers, the other being the ‘RA O equivalent' view. Left ventricular volumes wer estimated by applying the area-length method to both two-dimensional echocardiograms and cine-angiograms, consistently including in the former the left ventricular outflow tract of the ‘RAO equivalent' view. The echocardiographic approach employed was shown to yield good predictions of the angiographic results. For the end-diastolic volume the correlation is characterized by r=0.98 and SEE 21 ml or 9.7% of the angiographic mean and for the end-systolic volume by r=0.97 and SEE 17 ml or 18.1% of the mean. The correlation for the ejection fraction showed an r value of 0.87 and a SEE of 5.4%. Equally good correlations were obtained in the subgroup with wall motion disorders for which the r values of the end-diastolic and end-systolic volumes were both 0.98 and that of the ejection fraction was 0.8

Dynamics of aortic flow in hypertrophic cardiomyopathy

The purpose of this study was to reassess left ventricular ejection dynamics in hypertrophic cardiomyopathy, to investigate whether a premature stoppage of ejection occurs, as previously reported, and whether reliable criteria for left ventricular outflow tract obstruction can be established by non-invasive evaluation of aortic flow patterns. In a group of 21 patients with hypertrophic cardiomyopathy, composed of 9 with the obstructive form (HOCM), 9 with the non-obstructive form (HNCM) and 3 with apical hypertrophy (HACM), instantaneous flow velocities across the ascending aorta were determined non-invasively with a 16-gated Doppler 2-D echo instrument. Ten normals served as controls. The 16 flow velocities were averaged over 8 heart beats and the relative volume flow rate was calculated by microprocessor analysis. Ejection time (i.e. flow time) derived from the flow curves was compared with the available ejection period as determined from the carotid pulse tracing. In normals, ejection time amounted to 94±3% of the available ejection period, in HOCM to 92±5% and in HNCM to 93±4% (no significant differences). In HACM, however, ejection time was reduced to 71±14% of the available ejection period. In contrast to HNCM, aortic flow in HOCM was characterized by an early peak followed by a plateau at a sizeably lower flow level for the rest of systole. Flow time of an abnormally short duration was the hallmark of HACM. We conclude that in patients with hypertrophic cardiomyopathy, HOCM and HNCM can be distinguished by the shape of their volume flow curves. A premature stoppage of ejection is only found in patients with HAC

A comparison between single gate and multigate ultrasonic Doppler measurements for the assessment of the velocity pattern in the human ascending aorta

The velocity pattern in the ascending aorta of 15 healthy adults was measured quasisimultaneously from the Doppler-shifts produced in 16 gates distributed equally within the cross-section along a narrow ultrasound beam which centrally traversed the vessel upstream of the brachiocephalic trunk. A comparison between the time integrals of the velocities in gates 9 (centre line), 4 and 13 (off centre) and the time integral of the weighted mean of the velocities of all gates correlated with r=0.90, SEE=1.05 (gate 9), r=0.90, SEE 0.88 (gate 4) and r=0.92, SEE 0.94 (gate 13). A better correlation (r=0.96, SEE=0.60) was found between the linear mean of all gates and the weighted mean. These results show that Doppler measurements in single small gates are not appropriate to determine the average cross-sectional blood flow velocity in healthy adult

Comparison of intravenous digital subtraction cineangiocardiography with conventional contrast ventriculography for the determination of the left ventricular volume at rest and during exercise

Left ventricular volumes were determined by means of digital subtraction cineangiocardiography (DSA) which was performed in the right anterior oblique projection after contrast agent injection into the superior vena cava. Monoplane end-diastolic (EDV), end-systolic volumes (ESV), and ejection fraction (EF) were calculated using the ‘area-length' method and were compared with the same parameters obtained by conventional left ventricular cineangiocardiography. A first group of 20 patients was studied at rest and a second group of 10 patients during bicycle exercise at a work load of 64 watts during 2 min, by DSA and conventional cineangiocardiography. Three different subtraction modes were evaluated: (1) mask mode subtraction (MMS), (2) time interval difference (TID) method and (3) a combination of MMS and TID called MMS+TID method. With the MMS method good correlations were obtained for EDV, ESV and EF at rest (r>0.91) and during exercise (r>0.91). The TID method showed only moderate correlations for patients at rest (r>0.86) and during exercise (r>0.79). Similar results as with MMS were achieved by the combined method (MMS+TID) at rest (r>0.91) and during exercise (r>0.91). Interobserver variability indicated a high reproducibility for all methods except for TID during exercise. It is concluded that DSA is an accurate technique for left ventricular volume determination not only at rest but also during exercise. The best results are obtained with MMS or MMS+TID methods, while left ventricular contour detection is easier and more convenient with MMS+TI

Potential role of coronary vasoconstriction in ischaemic heart disease: effect of exercise

Coronary vasomotion plays an important role in the regulation of coronary perfusion at rest and during exercise. Normal coronary arteries show coronary vasodilation of the proximal (+20%) and distal (+40%) vessel segments during supine bicycle exercise. However, patients with coronary artery disease show exercise-induced vasoconstriction of the stenotic vessel segments. The exact mechanism of exercise-induced stenosis narrowing is not clear but might be related to a passive collapse of the disease-free vessel wall (Venturi mechanism), elevated plasma levels of circulating catecholamines, an insufficient production of the endothelium-derived vesorelaxing factor or increased platelet aggregation due to turbulent blood flow with release of thromboxane A2 and serotonin. Various vasoactive drugs, such as nitroglycerin and calcium antagonists, prevent exercise-induced stenosis vasoconstriction. An additive effect on coronary vasodilation of the stenotic vessel segment was observed after combination of nitroglycerin with diltiazem. Thus, exercise-induced stenosis narrowing plays an important role in the pathophysiology of myocardial ischaemia during dynamic exercise. The antianginal effect of vasoactive substances can be explained—besides the effect on pre- and afterload—by a direct action on coronary stenosis vasomotio

Fluorescence spectroscopy for identification of atherosclerotic tissue

Objective: Vessel perforation and limited steerability of the laser light are the major limitations of laser angioplasty. To improve steerability fluoresence spectroscopy has been proposed for identification of atherosclerotic plaques. The aim was to investigate this. Methods: Fluorescence spectroscopy with three different excitation wavelengths (325 nm, 380 nm, 450 nm) was tested in an emission range of 400 nm to 600 nm. Intensity ratios at 480/420 nm were determined in different types of blood vessels. Necropsy material from 40 patients (punch biopsies of 4 mm diameter from the coronary and carotid artery as well as from the ascending and descending aorta) was studied spectroscopically. Histological alterations of the vessel wall were assessed by a semiquantitative score (0 to 10 points): (a) normal tissue, 0 to 2 points (mean=0.25; n=38); (b) mild atherosclerotic lesions, 3 to 5 points (mean=3.35; n=39); (c) severe atherosclerotic lesions, ≥ 6 points (mean=6.75; n=43). Results: Best spectroscopic results were obtained with an excitation wavelength of 325 nm. In samples with severe atherosclerotic lesions the fluoresence spectra showed a significant reduction of the emitted wavelength intensities when compared to normal tissue. There was a clear separation of the fluorescence spectra between normal and mild as well as between normal and severe atherosclerotic lesions; normal tissue showed an increased intensity in the range from 420 nm to 540 nm, whereas atherosclerotic lesions had no or only a small peak at 480 nm. There was a significant correlation between the semiquantitative score (n=120) and the fluorescence ratio at 480/420 nm (excitation wavelength 325 nm) with a correlation coefficient of 0.87. The spectroscopic results showed no differences between the samples taken from different types of vessels. Conclusions: Fluorescence spectroscopy allows a reliable identification of normal and atherosclerotic lesions. The close correlation between the emitted light intensity ratio at 480/420 nm and the histological alterations of the vessel wall suggests a relationship between vessel wall fluorescence and the atherosclerotic alterations of the wal

Swiss clinical practice guidelines on field cancerization of the skin.

Actinic keratosis (AK) affects millions of people worldwide, and its prevalence continues to increase. AK lesions are caused by chronic ultraviolet radiation exposure, and the presence of two or more AK lesions along with photodamage should raise the consideration of a diagnosis of field cancerization. Effective treatment of individual lesions as well as field cancerization is essential for good long-term outcomes. The Swiss Registry of Actinic Keratosis Treatment (REAKT) Working Group has developed clinical practice guidelines for the treatment of field cancerization in patients who present with AK. These guidelines are intended to serve as a resource for physicians as to the most appropriate treatment and management of AK and field cancerization based on current evidence and the combined practical experience of the authors. Treatment of AK and field cancerization should be driven by consideration of relevant patient, disease, and treatment factors, and appropriate treatment decisions will differ from patient to patient. Prevention measures and screening recommendations are discussed, and special considerations related to management of immunocompromised patients are provided

Temperature Evolution of Sodium Nitrite Structure in a Restricted Geometry

The NaNO$_{2}$ nanocomposite ferroelectric material in porous glass was studied by neutron diffraction. For the first time the details of the crystal structure including positions and anisotropic thermal parameters were determined for the solid material, embedded in a porous matrix, in ferro- and paraelectric phases. It is demonstrated that in the ferroelectric phase the structure is consistent with bulk data but above transition temperature the giant growth of amplitudes of thermal vibrations is observed, resulting in the formation of a "premelted state". Such a conclusion is in a good agreement with the results of dielectric measurements published earlier.Comment: 4 pages, 4 figure