The clinical incidence of Pacemaker-Mediated Tachycardia (PMT) has been substantially reduced with the availability of wide range postventricular atrial refractory period (PVARP) programmability in most current technology DDD pacemakers. However, patients may still be at clinical risk for PMT if the PVARP must be reduced to allow higher atrial tracking capability or VA conduction (VAC) is not periodically assessed to ensure adequate PVARP selection. A new DDD pacer (Siemens-Pacesetter Model 2010T) incorporates programmable responses to a sensed PVC to prevent PMT induction due to VAC following a PVC. In each of these responses, the PVARP is automatically extended to prevent detection of the retrograde P wave, thus preventing the PMT. Additionally, should a PMT occur for reasons other than a PVC, the selected PVARP extension algorithm is periodically invoked to terminate the PMT. This study was conducted to evaluate the operation and clinical benefit of these PVC response functions and PMT termination capabilities. The exact timing operation of the pacer during these responses is also reviewed.

Cardiac Complexes, Premature↗

PubMed1987

A method for the quantitative analysis of ELISA data.

A method is described for measuring relationships among virus serotypes. An indirect ELISA was used to obtain antibody-response curves for homologous and heterologous combinations of virus and dilutions of antibody. Data from the proportional response region of each curve were converted to logarithmic values and subjected to a form of regression analysis to derive relative titres for the various combinations of virus and antibody. SDI values were then obtained by calculating the mean difference in relative titres between homologous and reciprocal heterologous combinations. Virus models in two different groups were examined using this technique. Relative titres obtained were consistent and reproducible over several experiments indicating that the technique was capable of reliably discriminating among serotypes which differed by as little as 0.2 SDI.

Enzyme-Linked Immunosorbent Assay↗

PubMed1986

Characteristics and clinical effects of myopotential signals in a unipolar DDD pacemaker population.

Myopotential signals were recorded from atrial and ventricular leads during isometric exercise in 25 patients who had chronically implanted dual chamber pacemakers using the electrogram telemetry capability of the pacemakers. Average electrogram amplitude on the atrial channel was 0.92 mV (range 0.3 to 1.9) and on the ventricular channel was 0.98 mV (range 0.3 to 2.2); the difference was not significant. There was a strong correlation (R = 0.82) between the amplitude of myopotentials on the atrial and ventricular leads for individual patients. Myopotential sensing caused ventricular output inhibition in two patients (8%) and ventricular tracking in sixteen patients (64%). Pacemaker reprogramming abolished ventricular myopotential inhibition in all patients and stopped ventricular myopotential tracking in seven patients. We conclude that myopotentials can be analyzed and their effects ameliorated by a multiprogrammable pacemaker with electrogram telemetry capability.

Adult↗

PubMed1978

Adequate health care: one step toward social justice.

Explore the source record for details and available documents.

Catholicism↗

PubMed1977

Characteristics of the microplate method of enzyme-linked immunosorbent assay for the detection of plant viruses.

Some characteristics of a microplate method for the detection and assay of plant viruses using enzyme-labelled antibodies are described. The method enabled the highly sensitive detection of a number of morphologically different viruses in purified preparations and in unclarified extracts of herbaceous hosts and of infected crop plants. Virus concentrations were estimated by photometric measurement of the colour intensity of the hydrolysed substrate. The suitability of the tehcnique for various field and research applications is considered.

Enzyme-Linked Immunosorbent Assay↗

PubMed1976

The detection of viruses by enzyme-linked immunosorbent assay (ELISA).

The use of enzyme-linked antibodies for the detection of two morphologically different plant viruses is described. The technique is extremely sensitive, enabling assay of the viruses at concentrations as low as 10 to 100 ng/ml both in purified preparations and in crude plant extracts.

Alkaline Phosphatase↗

PubMed1972