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Biomedical subjects

D L Roberts

Publications and source records attributed to D L Roberts.

103 records · Page 6Linked to original sources
PubMed1976

Ventricular arrhythmias and cardiac hemodynamics in patients with myocardial infarction. Comparison of the acute and post-hospitalization phases.

Sixty-six patients with myocardial infarction (MI) were studied during the acute hospital phase and during the six months after hospital discharge. The clinical characteristics, location of infarction, and data from right heart catheterization were studied in an attempt to determine what factors were associated with ventricular rhythm disturbance. Those patients with serious ventricular arrhythmias (SVA) in the acute phase of infarction were found to have a significantly greater degree of myocardial dysfunction as measured by pulmonary artery and pulmonary wedge pressure than patients with more normal rhythm (p less than .05). Clinical classification of patients and location of infarction were not helpful in predicting SVA during the acute infarction period. Knowledge of hemodynamic data, presence of SVA and clinical characteristics in the acute infarction period were of no value in predicting the occurrence of SVA after hospital discharge patients having had an acute diaphragmatic infarction were found to have a higher incidence of SVA after hospital discharge.

Acute Disease↗
PubMed1976

Origin of great cardiac vein and coronary sinus drainage within the left ventricle.

The relative contributions of left anterior descending (LAD) and left circumflex (LC) arterial inflow to blood sampled at various points within the great cardiac vein (GCV) and coronary sinus (CS) have been investigated in open-chest dogs. Dissolved helium (He) and hydrogen (H2) were infused into external circuits perfusing the LAD and LC, respectively, and their steady-state concentrations were measured chromatographically at various points within the GCV and CS. Under basal conditions GCV H2 averaged only 5% of mid-CS H2 and did not change greatly during alterations of preload and afterload or during selective LAD or LC obstruction and vasodilation. The relationship of mid-CS He to GCV. He was more variable under basal conditions and changed noticeably during selective changes in LAD or LC inflow. Appreciable amounts of He were present consistently in left marginal vein drainage. We conclude that: 1) GCV blood is remarkably free of LC inflow in both normal and abnormal physiological states; 2) the origin of mid-CS blood is more variable, both from animal to animal and in individual animals before and after interventions; 3) a portion of LAD drainage normally reaches the CS through circumflex venous branches rather than the GCV.

Animals↗
PubMed1976

ST-segment variations after acute myocardial infarction. Relationship to clinical status.

The degree of vectorcardiographic ST-segment elevation was employed as an index of myocardial ischemic injury in a study of 27 patients after acute myocardial infarction (AMI). The ST-segment vector magnitude (STVM) was derived from the continuously recorded modified Frank vectorcardiogram and was plotted serially by hours after onset of AMI. The STVM in normal subjects was 51.1 +/- 7.1 muV (mean +/- SE). A standard deviation of the pooled variance of 15.2 muV was obtained in a group of control patients and a change of more than 2 SD (greater than 30 muV) in an individual STVM was considered to be significant. The STVM progressively decreased in patients who survived without clinical complications while it remained elevated in those with congestive heart failure. A modest, sustained re-elevation of STVM was observed in patients who developed pericarditis, and a significant late average increase of 64 muV occurred in survivors with infarct extension. In contrast, STVM underwent a major increase in patients who died. In five of these six patients without associated pericarditis a mean increase of 164 muV was recorded in the last 5-12 hours of life. While death was clinically predictable in two patients with cardiogenic shock, it was not so for the four other patients who died. Thus, major increases in STVM frequently suggested significant new ischemic injury and were often premonitory to sudden death after AMI. The increases preceding death implied that not only ventricular extopy but also lethal conduction abnormalities after AMI might be ischemia-related.

Acute Disease↗
PubMedDate not supplied

HELLP syndrome and cholecystitis: case report and review of the literature.

A case of the HELLP syndrome is reported that was initially diagnosed as cholecystitis. Much overlap exists between the two diagnoses, and the emergency physician must be aware of the important differences between them. Because the HELLP syndrome and preeclampsia may occur in both the second and third trimesters, they represent serious diagnoses that must be considered when evaluating a pregnant patient with right upper quadrant abdominal pain.

Acute Disease↗
PubMedDate not supplied

A preliminary study of the activation of endogenous pancreatic exocrine enzymes during automated porcine islet isolation.

The activation of endogenous pancreatic enzymes during automated pancreas digestion may be detrimental to islet isolation. In this report we assessed the activation of trypsin, chymotrypsin, elastase, carboxypeptidases A and B, phospholipase A2, and lipase using a porcine model. Four islet isolations were examined. Duplicate aliquots were taken from the automated circuit at 5-min time intervals up to the completion of pancreas digestion (approx 60 min). One aliquot was activated in vitro with exogenous trypsin in order to convert the enzymes into their active non-"proform," with the exception of trypsinogen, which was activated with exogenous enterokinase. This was done to assess the percentage activation of each individual enzyme (total potentially activatable enzyme release). The extent of activation between isolations was extremely variable. During the closed (recirculating) circuit phase of pancreas digestion there were both gradual and rapid increases in the levels of enzymes released. Peak activity of enzyme activation varied from 13 to 30 min; similarly, total potentially activatable peaks occurred between 13 and 38 min. Lipase and carboxypeptidase B showed greater than 70% activation, chymotrypsin, carboxypeptidase A, and phospholipase A2 between 50% and 70% activation, and trypsin and elastase less than 20%. There were up to 30-fold differences between the four islet preparations. In summary, it is unlikely that poor islet yields are soley explained by variations between collagenases; the variable activation of endogenous pancreatic exocrine enzymes is also likely to be influential to porcine islet yields.

Animals↗