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Biomedical subjects

J Peregrin

Publications and source records attributed to J Peregrin.

At least 127 records · Page 7Linked to original sources
PubMed1981

Averaging, selective averaging and latency-corrected averaging.

Although latency-corrected averaging and selective averaging represent frequency used alternatives to the time-locked averaging, little is known about the changes of the signal-to-noise ratio (SNR) associated with their application. For this reason, visual evoked responses (VERs) to blank and checkerboard patterned flashes of light (5.6 cd/m2) were recorded in 15 subjects using a referential (Oz - A1 + 2) and a bipolar (Oz - Pz) derivation, and interstimulus intervals (ISI) of 1.4s and 2.4s; SNRs were calculated for all combinations. With time-locked averaging (referential derivation) the mean SNR of single VERs was 0.35 to blank stimuli and 0.68 to patterned stimuli. With latency-corrected averaging, the means SNR rose to 0.56 (0.74), and with selective averaging it increased to 0.81 (1.00). A combined procedure of selective and latency-corrected averaging yielded the highest mean SNR values of single VERs: 0.98 (1.21). Increasing ISIs from 1.4 - 2.4s did not change the results; the mean SNR values were always higher in bipolar than in referential derivations. The selective, latency-corrected averaging produced higher SNRs, and the group mean number of detectable single VERs (62% of the single VERs to blank stimuli, and 74% of the single VERs to patterned stimuli) and the latency variability of the single VERs: -0.33 +/- 14.5 ms (blank stimulation) and -0.48 +/- 13.96 ms (patterned stimulation).

Adult↗
PubMed1980

Effect of myocardial revascularization on the left ventricular function. Diagnosis of reversible contraction abnormalities.

Function of the left ventricle was evaluated in 28 men during the early postoperative period after myocardial revascularization by left ventricular cineangiograms. The group was characterized by patency of all aorto-coronary grafts and the absence of a new Q waves on the ECG. Improvement of the global left ventricular function occurred in a sub-group of patients with reduced ejection fraction before operation as well as in patients with segmental disturbances of left ventricular contraction. The segmental contractions improved significantly in the revascularized areas where prior to operation the function was impaired. The postoperative change was in some patients predicted before operation by administration of sublingual nitroglycerin and by means of postextrasystolic potentiation. We found the same trend of changes produced by the above stimuli and by revascularization.

Adult↗
PubMed1980

Contribution to the treatment of post-infarction cardiac aneurysms.

The authors discuss contemporary problems of resection of post-infarction cardiac aneurysms. In their opinion the main cause of left-sided cardiac failure is enlargement of the left ventricle which leads to increaser demands on the tension of muscle fibres and work of the heart. These mechanisms potentiate at the same time the ischaemia of the heart muscle. Reduction of the left ventricle by appropriate resection eliminates or improves markedly this adverse condition in particular when there is an opportunity of simultaneous revascularization by an aorto-coronary by-pass. Based on the results in a series of 52 operations the authors consider assessment of the stroke volume before and after the foreseen resection a suitable and reliable criterion for indication of the operation. Its application led to a substantial decline of the surgical mortality caused in particular by the postoperative low cardiac output syndrome.

Heart Aneurysm↗