PubMed Health⌕ Search

Biomedical subjects

L Becker

Publications and source records attributed to L Becker.

At least 163 records · Page 9Linked to original sources
PubMed1976

Effect of tachycardia on left ventricular blood flow distribution during coronary occlusion.

The effect of heart rate on the amount and distribution of collateral blood flow was determine in open-chested dogs 1 h after coronary artery ligation. Flows to ischemic and nonischemic regions of left ventricle were measured with 7- to 10- mum diam radioactive microspheres during base-line conditions (118 +/- 6 beats/min) and again during atrial pacing at rates 20 and 40% above control (141 +/- 7 and 165 +/- 9 beats/min). During pacing aortic and left atrial pressures and cardiac output did not change significantly, whereas ST segment elevation in epicardial electrograms increased markedly. In nonischemic myocardium, mean flow increased approximately in proportion to the increase in rate, but subepicardial (EPI) flow increased somewhat more than subendocardial (ENDO) flow. In ischemic myocardium, overall flow did not change significantly, but a redistribution from ENDO to EPO was seen. At the faster rate ENDO flow fell 25% (P less than 0.02), EPI flow increased slightly, and ENDO/EPI fell in 8/9 animals (mean 0.54-0.43, P less than 0.01). The ENDO/EPI maldistribution present in ischemic muscle is thus accentuated by tachycardia; this may account for part of the harmful effect of tachycardia in acute myocardial infarction and may help explain the disproportionate ENDO ischemia seen in angina pectoris.

Animals↗
PubMed1975

Reversal by phenylephrine of the beneficial effects of intravenous nitroglycerin in patients with acute myocardial infarction.

Nitroglycerin has been shown to reduce ST-segment elevation during acute myocardial infarction, an effect potentiated in the dog by agents that reverse nitroglycerin-induced hypotension. Our study was designed to determine the effects of combined nitroglycerin and phenylephrine therapy. Ten patients with acute transmural myocardial infarctions received intravenous nitroglycerin, sufficient to reduce mean arterial pressure from 107 +/- 6 to 85 +/- 6 mm Hg (P less than 0.001), for 60 minutes. Left ventricular filling pressure decreased from 19 +/- 2 to 11 +/- 2 mm Hg (P less than 0.001). SigmaST, the sum of ST-segment elevations in 16 precordial leads, decreased (P less than 0.02) with intravenous nitroglycerin. Subsequent addition of phenylephrine infusion, sufficient to re-elevate mean arterial pressure to 106 +/- 4 mm Hg (P less than 0.001) for 30 minutes, increased left ventricular filling pressure to 17 +/- 2 mm Hg (P less than 0.05) and also significantly increased sigmaST (P less than 0.05). Our results suggest that addition of phenylephrine to nitroglycerin is not beneficial in the treatment of patients with acute myocardial infarction.

Acute Disease↗
PubMedDate not supplied

Out-of-hospital cardiac arrest in octogenarians and nonagenarians.

BACKGROUND: Studies of elderly patients who have out-of-hospital cardiac arrest have contradictory results. The studies usually define elderly patients as those older than 70 years, and include relatively few octogenarians and nonagenarians. OBJECTIVES: To compare the survival after out-of-hospital cardiac arrest of octogenarians, nonagenarians, and younger patients and to determine the influence of age on survival after adjusting for factors known to influence out-of-hospital cardiac arrest outcome. METHODS: We conducted a retrospective cohort study in suburban King County, Washington, on 5882 patients who had out-of-hospital cardiac arrest from presumed cardiovascular disease between January 1, 1987, and December 31, 1998, and who received cardiopulmonary resuscitation from bystanders, emergency medical technicians, or both. The main outcome measure was survival to hospital discharge. RESULTS: In patients who had out-of-hospital cardiac arrest due to a cardiac cause, younger patients had higher hospital discharge rates than octogenarians, who in turn had higher hospital discharge rates than nonagenarians (19.4% vs 9.4% vs 4.4%; P<.001). However, survival to hospital discharge improved significantly for younger patients, octogenarians, and nonagenarians who had ventricular fibrillation or pulseless ventricular tachycardia (36% vs 24% vs 17%; P<.001). After multiple logistic regression analysis controlling for other factors, increased age was weakly associated with decreased survival to hospital discharge (odds ratio, 0.92; 95% confidence interval, 0. 85-0.99). CONCLUSIONS: Octogenarians and nonagenarians have lower survival to hospital discharge than younger patients, but age is a much weaker predictor of survival than other factors such as initial cardiac rhythm. Decisions regarding resuscitation should not be based on age alone. Arch Intern Med. 2000;160:3439-3443.

Aged↗
PubMedDate not supplied

The impact of television public service announcements on the rate of bystander CPR.

OBJECTIVE: To determine whether televised public service announcements (PSAs) demonstrating the fundamentals of CPR were effective in increasing the rate of layperson bystander-initiated CPR. METHODS: Two 30-second PSAs were shown 597 times from September 8, 1996, through April 12, 1997. In each, CPR was given to one member of an older couple by the other in the home. The authors measured rates of bystander CPR in communities that were exposed to the PSA and in communities that were not exposed in two time periods, a before-airing period, January 1, 1993, through September 7, 1996, and a during-airing period, September 8, 1996, through April 12, 1997. A case was defined as a patient with a nontraumatic cardiac arrest that occurred before arrival of EMS personnel, and for whom CPR was initiated by EMS personnel or lay bystanders. RESULTS: There were 1,786 cardiac arrests in the "before" period and 289 in the "during" period. The rate of bystander CPR increased from 43% to 55% (p<0.05) in the intervention community and remained the same in the comparison community (33%). CONCLUSION: Airing of the PSA was accompanied by an increase in the rate of bystander CPR, though the increase may be attributable to a secular trend.

Aged↗
PubMedDate not supplied

The gas fireplace: a new burn hazard in the home.

Gas fireplaces have become popular in recent years. This article presents the first reported case of a burn injury from contact with the glass front of a gas fireplace. An investigation of the surface temperature of the glass fronts of gas fireplaces was undertaken to clarify the risks posed by these units. Surface temperature measurements of the glass fronts of 3 common gas fireplace models were obtained using a thermocouple probe. Glass temperatures reached 200 degrees C within 6.5 minutes of ignition, climbing to 245 degrees C at 14 minutes after ignition. Glass temperature continued to rise beyond this point, but it could not be monitored because the adhesives securing the thermocouple probe melted. Glass temperatures of 50 degrees C were recorded at 30 minutes after the unit was shut off. The temperatures of the glass fronts of glass fireplaces are sufficient to cause cutaneous burns within seconds of contact both while the fireplace is in use and up to one half hour after it has been turned off. Current industry safety standards are not directed at the prevention of contact burns. We recommend that (1) mechanical guards be installed to create a barrier in front of the glass; (2) strict warning labels be applied to the units and ignition switches; and (3) burn prevention information be distributed with the owner's manual for these products.

Accidents, Home↗
PubMedDate not supplied

Reproducibility of mental stress-induced myocardial ischemia in the Psychophysiological Investigations of Myocardial Ischemia (PIMI).

OBJECTIVE: Many patients with coronary artery disease (CAD) develop myocardial ischemia in response to mental stress. This has been documented both in the natural environment and in the laboratory. However, the reproducibility of laboratory mental stress-induced ischemia has not been investigated. METHOD: Sixty patients with documented CAD and a positive exercise stress test discontinued cardiac medications and underwent two standardized mental stress tests (a timed Stroop Color-Word test and a public speaking task) in a nuclear cardiology laboratory (Visit 1), and repeated this procedure between 2 and 8 weeks later (Visit 2). Measurements of cardiovascular function and neurohormonal responses were obtained throughout testing, and mood state was assessed before and after testing. RESULTS: Sixty-eight percent of the 56 patients with detailed radionuclide data from both visits had consistent responses (ie, ischemia either present during both sessions or absent during both) to the Stroop task (kappa = .29, p = .03), 61% had consistent responses to the speech task (kappa = .20, p = .12), and 60% had consistent responses when ischemia was considered present if it occurred during either the Stroop test, the speech task, or both, and absent if it did not occur during either task (kappa = .22, p = .07). Hemodynamic and neuroendocrine responses to the tests were moderately reproducible. CONCLUSIONS: We conclude that two popular laboratory tests for mental stress-induced myocardial ischemia are modestly reproducible. The relatively low reproducibility is probably influenced by uncertainties in detecting relatively small changes in wall motion, habituation of the patient to repeated exposure to psychological stressors, and physiological differences in threshold for ischemia on different days of testing.

Adult↗