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PubMedDate not supplied

Automated measurement and frequency analysis of the pneumocardiogram.

The flow pneumocardiogram (PnCG), ie, measurement of cardiogenic gas movement in and out of the lung during apnea, was transduced by an in-line, high-gain pneumotachograph. A portion of the differentiated PnCG, the dPn/dt IJ wave, has been shown previously to correlate closely with left ventricular function. A simple analog device was designed and tested to measure the dPn/dt IJ amplitude on a practical beat-to-beat basis. Frequency-power spectral analysis showed the PnCG to be a low frequency phenomenon with the systolic component in the 9-to-10-Hz range. Appropriate band-pass filtering of the PnCG and its applicability as an intraoperative monitoring device are presented.

Analog-Digital Conversion↗
PubMedDate not supplied

Digital x-ray imaging: the basics.

This article defines the terminology of digital imaging and presents an introduction to several modalities, with emphasis on digital video subtraction angiography. Topics discussed include special imaging considerations and problems, operating modes, and equipment configuration.

Analog-Digital Conversion↗
PubMed1984

[Digital subtraction ventriculography in determining global and regional left ventricular parameters compared to left catheterization cardiography].

Since May 1982 we studied more than 150 patients with heart diseases by means of digital angiography, out of them 46 patients with a history of transmural myocardial infarction were selected. Urografin 76, 30 ml, was administered at a flow rate of 18 ml/s by means of a catheter in the superior vena cava during digital subtraction ventriculography. Results were compared with conventional contrast ventriculograms. The correlation coefficient was r = 0.93 (p less than 0.001) for determination of ejection fraction with both methods. The data in individual cases suggest that DSV is more sensitive than conventional contrast ventriculography in determination of severely reduced ejection fractions. The methods are practically identical in qualitative evaluation of disorders of regional wall motion in the anterolateral region, while DSV is more sensitive than conventional ventriculography in evaluating the apical region. Sensitivity was 85.7% when the two methods were compared in evaluation of the inferior region of the left ventricle. Both methods are identical in demonstration of severely deformed ventricles. Digital subtraction ventriculography may replace conventional contrast ventriculography in some of the situations discussed above.

Analog-Digital Conversion↗
PubMed1984

[Present status of digital subtraction angiography].

The present state of development of digital subtraction angiography can be characterised by the fact that, according to the results obtained so far, it can be most useful as a diagnostic method, depending on the clinical problems involved and on the condition of the patient, taking into consideration any possible history of patient allergy and the state of his cardiac and renal functions; if there are no contra-indications, the requisite contrast medium can be applied intravenously or intra-arterially. This method can also be used as a complement to conventional large-format angiography to obtain additional information; in other cases, it may not supply information in sufficient detail, thus requiring subsequent large-format angiography. Diagnostic safety of this method is more than 95% in all the essential indications, such as diagnosis of extracranial cerebrovascular disturbances of blood flow, detection of aneurysms of the aorta, evaluation of postoperative and post-treatment conditions in the vascular system, as well as renovascular hypertension. However, an essential prerequisite is the appropriate use of technical aids fitted to the equipment used for examination. Other essential requirements are the best possible positioning of the patient and his ability to cooperate.

Analog-Digital Conversion↗