Electrocardiographic evaluation of collateral development in conscious dogs

In seven conscious dogs, endocardial ST-segment changes within the central ischemic area at 2 min after coronary occlusion were compared with the amount of reactive hyperemia and collateral blood flow. With the use of ultrasonic dimension gauges implanted in the subendocardium perfused by the left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCCA), endocardial electrocardiograms and regional myocardial dimensions were simultaneously measured. Collateral vessels were developed by repeated 2 min LCCA occlusions during three weeks. Blood flow debt repayment following the release of LCCA occlusion was measured using a Doppler flowmeter. The collateral blood flow from LCCA to the area supplied by the occluded LAD was measured as a stepwise reduction in LCCA flow upon the release of LAD occlusion. With the attenuation of myocardial ischemia due to the collateral development, endocardial ST-segment shift revealed earlier restoration compared with subendocardial function. In the presence of mild ischemia, the ST-segment was still elevated. Thus, endocardial ST-segment changes serve as an indirect functional index of collateral development as well as regional myocardial function and blood flow debt repayment.

Esthesioneuroblastoma metastatic to the trachea

Esthesioneuroblastoma is an uncommon nasal neoplasm of neural crest origin, which is recognized for its propensity for local recurrence and distant dissemination by both lymphatic and hematogenous routes. Hematogenous spread occurs most frequently to the lungs and bones, but metastases to the liver, spleen, scalp, face, breast, adrenal, aorta, and ovary have been reported. We present a patient who developed metastatic esthesioneuroblastoma of the trachea 1 year after successful craniofacial resection of his primary tumor. The patient was treated by YAG laser resection of the metastatic tumor followed by radiotherapy. He was free of tracheal disease 1 year after treatment of the metastases.

Characterization of nonischemic segment shortening during variable extent of myocardial ischemia in conscious dogs

Studies were performed on seven conscious dogs chronically instrumented for measurement of subendocardial segment length in the central area perfused by the left circumflex coronary artery (LCCA) and left anterior descending coronary artery, LCCA flow, and left ventricular pressure. We occluded the LCCA for 2 min using an externally inflatable pneumatic occluder placed around the proximal LCCA. Two-minute LCCA occlusions were repeated hourly for 8 h, 5 days/week. The first LCCA occlusion decreased the ejection phase shortening in the ischemic area from 22.2% +/- 2.5% (SEM) to 3.1% +/- 0.7% (P less than 0.001). Concomitantly, heart rate increased from a resting rate of 76 +/- 4 to 117 +/- 6 beats/min (P less than 0.001) after 2 min of LCCA occlusion, and ejection phase shortening in the nonischemic area decreased from 25.5% +/- 1.3% to 21.6% +/- 1.1% (P less than 0.001) despite increases in end-diastolic segment length (15.31 +/- 1.46 mm to 15.69 +/- 1.52 mm, P less than 0.01). These changes in non-ischemic segment shortening and heart rate during LCCA occlusion were attenuated progressively with improvement tin the regional myocardial function at jeopardy due to the development of collateral circulation, and a significant (P less than 0.001) correlation between both the reduced nonischemic segment shortening and the increased heart rate with the degree of dysfunction in the ischemic region was obtained by linear regression analysis with Fisher's Z transformation.

Effect of myocardial contraction on systolic coronary resistance in conscious dogs

We studied the effect of cardiac contraction on systolic coronary resistance under the conditions of maximally dilated coronary resistance vessels in six conscious dogs. Subendocardial segment length in areas supplied by the left circumflex coronary artery, left ventricular pressure and left circumflex coronary artery flow were simultaneously measured. At 5 sec after release of the first 2 min of left circumflex coronary artery occlusion, diastolic coronary blood flow revealed its peak value in association with markedly depressed regional contractile function. With collateral development induced by repeated 2 min left circumflex coronary artery occlusions, segmental dysfunction during occlusion and early reperfusion was progressively attenuated. Before and after collateral development, diastolic coronary resistance at 5 sec of reperfusion remained unchanged, but systolic coronary resistance increased by 41% secondary to restoration of regional myocardial shortening. In each animal, normalized regional shortening correlated well with changes in systolic coronary resistance. The fraction of systolic coronary resistance due to active regional myocardial contraction was 52%. These studies demonstrate that when coronary vasomotor tone is abolished, regional myocardial contraction impedes the coronary systolic flow in proportion to the extent of shortening.

Diurnal changes in coronary blood flow in conscious dogs

The purpose of the present study was to evaluate potential diurnal changes in resting coronary blood flow under conditions of comparable myocardial oxygen requirements. We studied 21 conscious, resting dogs instrumented for the measurement of coronary flow, left ventricular pressure, and regional myocardial segment length. Recordings were taken in the early morning and late afternoon. In the afternoon, left circumflex coronary blood flow was 12.8% higher than in the morning, without detectable changes in the major hemodynamic determinants of myocardial oxygen consumption, i.e., heart rate, left ventricular pressure, peak positive dP/dt, end-diastolic regional myocardial dimension, and regional myocardial stroke work. These results are consistent with a circadian variation of coronary vascular tone accompanied by compensatory alteration in myocardial oxygen extraction and may have clinical relevance, since the coronary vascular tone may change dynamically in patients with critical coronary stenosis.

Evaluation of coronary collateral development by regional myocardial function and reactive hyperaemia

The development of collateral vessels was induced by repeated brief left circumflex coronary artery occlusions in 11 conscious dogs. Subendocardial segment shortening in the central ischaemic area and the ischaemic marginal area and transmural wall thickening in the centre of the ischaemic area were measured together with circumflex coronary flow. Changes in regional myocardial function and reactive hyperaemia were determined daily. The rate of recovery of myocardial function after collateralisation was almost identical in both regions. Before myocardial contractility was restored reactive hyperaemia was greatly attenuated. These data strongly suggest that collateral flow is distributed uniformly over the ischaemic bed and that substantial areas of myocardial tissue at risk are salvaged from ischaemia as a result of effective collateral circulation.

Acceleration of coronary collateral development by heparin in conscious dogs

We evaluated whether heparin pretreatment accelerates the development of coronary collateral vessels induced by repeated, brief coronary occlusions. Sixteen dogs were instrumented for the measurement of subendocardial segment length in the area perfused by the left circumflex coronary artery (LCCA), LCCA flow and left ventricular pressure. An externally inflatable pneumatic occluder was placed around the LCCA. Two min coronary occlusions (CO) at rest were repeated hourly until there was no reduction in ischemic segment systolic shortening at the end of CO and negligible reactive hyperemia following the release of CO. Eight control dogs developed collaterals sufficient for resting myocardial oxygen requirements in the LCCA region by 129 +/- 45 (SD) CO. The remaining 8 dogs given heparin daily developed collaterals by 81 +/- 33 CO (p less than 0.05). Thus, in the presence of severe myocardial ischemia known to promote collateralization, heparin accelerated the development of coronary collaterals.

Modulation of synchrony of left ventricular contraction by regional adrenergic stimulation in conscious dogs

The sympathetic innervation of the left ventricle provides a potential mechanism for modulation of synchrony of myocardial contraction. Dogs were instrumented to measure left ventricular pressure and segment length in the posterior region of the left ventricle perfused by the circumflex artery (PSL) and in an anterior region perfused by the anterior descending artery (ASL). Norepinephrine (NE) was injected into the circumflex artery using an indwelling catheter in bolus doses sufficient to produce no direct systemic effects. Intracoronary injection of NE resulted in significant increases in percent segment shortening and mean shortening velocity in the PSL. Duration of shortening in the PSL was significantly reduced. Percent shortening, velocity of shortening, and shortening duration in the ASL were unchanged. While there was no change in left ventricular systolic pressure, +dP/dtmax and -dP/dt min increased with intracoronary NE. These results demonstrate alterations in the synchrony of myocardial contraction following regional myocardial stimulation with intracoronary injections of NE at doses within the expected physiological range and suggest that activation of localized sympathetic neural pathways may result in problems involving mechanical performance of the heart.

Glare following posterior chamber intraocular lens implantation

We performed glare tests on patients following uncomplicated extracapsular cataract extraction and posterior chamber intraocular lens implantation and on noncataractous phakic patients. Three types of lenses were implanted to compare the effect of optic asphericity and ultraviolet filtration on glare. Glare testing was performed using the Miller-Nadler Glare Tester and Baylor Visual Function Tester. The glare scores of the pseudophakic and phakic patients were statistically similar. In the pseudophakic patients, factors associated with decreased glare performance were posterior capsular opacification and increased pupil size; the intraocular lens type did not significantly affect glare scores.

Changes in coronary flow following repeated brief coronary occlusion in the conscious dog

Studies were conducted in 12 conscious, unsedated dogs instrumented for measurements of subendocardial segment length in the area perfused by the left circumflex coronary artery, blood flow velocity of this artery, and left ventricular pressure. An externally inflatable pneumatic occluder was placed to occlude the circumflex coronary artery for selected durations at selected intervals. Resting coronary blood flow velocity was measured before and after collateral development induced by repeated brief coronary occlusion. Under conditions of comparable myocardial oxygen consumption, shown by the similar pressure-rate product, preocclusion resting coronary blood flow velocity of the repeatedly occluded artery decreased by 21.3% (P less than 0.001) in association with collateral growth. These findings strongly suggest that the perfusion territory of the collateralized artery decreases considerably secondary to the periodic ischemic stimulus.

Ultrasound and the intestinal wall: experimental methods

High-frequency, high-resolution ultrasound provides a new approach to imaging structures in the wall of the gastrointestinal tract. Questions about internal ultrasound include: is the ultrasound image specific for disease states, in which diseases will this technology add new and useful information not available from existing diagnostic studies, and what are the necessary characteristics for a system to accomplish these diagnoses? Answering these questions requires that precise correlations be made between the ultrasound image and pathology. We have developed a method to image a resected gastrointestinal tissue with ultrasound and to remove and examine the corresponding piece of tissue histologically. Changes in wall thickness, obliteration of layers, and changes in the characteristics of the tissue can be studied. We have shown that ultrasound can resolve the layers of the gut wall. This system should enable us to answer questions about which intestinal wall diseases are suitable for internal ultrasound imaging and characterize the engineering features of an optimal ultrasound system for clinical application.

Hemodynamic effects of hemorrhage and subsequent naloxone treatment in conscious rabbits

The central and peripheral hemodynamic effects of rapid hemorrhage and subsequent opiate receptor blockade were studied in conscious rabbits. With hemorrhage of less than 12 ml/kg, mean arterial blood pressure (BP) was maintained by an increase in total peripheral resistance (TPR). Cardiac output (CO) declined in spite of an increase in heart rate (HR). Blood loss greater than 13 ml/kg resulted in an abrupt decrease in BP that was largely due to a decline in TPR. CO continued to decline gradually as it did early in hemorrhage. HR also decreased at the transition to hypotension. Subsequent opiate receptor blockade with naloxone (3 mg/kg) produced a prompt increase in BP and a decrease in HR. An increase in TPR accounted for the rise in BP. CO did not change significantly after naloxone. Therefore the hypotension associated with hemorrhage results from a decline in peripheral vascular resistance that is reversible by opiate receptor blockade with naloxone. These results are consistent with the involvement of opiate receptors and endogenous opiate peptides centrally and/or peripherally in control of vascular resistance during acute hemorrhagic hypotension.

Influence of social variables on the biobehavioral response to separation in rhesus monkey infants

Effects of social stimuli on behavioral and physiological responses to separation were examined in 4-month-old rhesus monkeys. Infants were removed from their social group under 3 counterbalanced conditions: (1) infant totally isolated from its familiar physical and social environment and placed alone in a cage for 4 days; (2) "mother in"--housing the infant in a single cage in front of its social group with mother remaining in the group; (3) "mother out"--similar situation, except that mother was removed from the group during separation. Infant behavior was recorded, and, at selected times during separation, a blood sample was obtained for analysis of plasma cortisol. Infants rarely vocalized when totally isolated, but showed high vocalization and movement in the presence of their social groups. Vocalization was transiently higher in mother-out condition than in mother-in condition. Infants never showed signs of depression. Plasma cortisol response did not differentiate between groups. Animals showed significantly high levels of plasma cortisol 3 hours following separation. These data indicate that the responses of the infant following separation are attempts to produce effective coping responses. The concepts of "protest" and "despair" are discussed as they relate to behavioral differences observed following different separation paradigms.

"Swimmer's ear" among children of kindergarten age and water quality of swimming pools in 11 Kibbutzim

In an effort to determine if bacterial water quality was related to the incidence of otitis externa ("swimmer's ear") in kindergarten children, a prospective study was conducted between May and September 1980 in 11 communal agricultural settlements (kibbutzim) in Israel. High total bacterial count, total coliforms and fecal coliform counts were found to be positively associated with otitis externa. This association was enhanced when nondivers were separated from divers. Among the divers, the rate of ear inflammation was high regardless of water quality. Among nondivers at the time of the study, the rate of otitis externa was as high as 35.7% in swimming pools with poor quality water, and as low as 17.0% in those with good quality water (P = 0.03). Younger children had a slightly higher risk of otitis externa than had older children.

Hormonal responses accompanying fear and agitation in the squirrel monkey

The adrenocortical and gonadal responses of 14 male monkeys were evaluated during four experimental conditions in order to evaluate the influence of social interactions on endocrine responsiveness. Plasma hormone levels were determined during the establishment of social relations, after 60-min exposures to a novel environment, after 60-min exposures to a snake, and 60 min after ACTH administration. Both adrenal and gonadal secretion changed significantly during the first day after social relations were established, although only dominant males showed increases in testosterone, whereas cortisol levels rose in all subjects. Increases in cortisol, but not testosterone, were also observed following exposure to novelty or a snake. The presence of a social partner reduced signs of behavioral disturbance during these test conditions, although the adrenal responses were equivalent or greater than when tested alone. This finding qualifies earlier research which indicated that social support was beneficial for reducing stress when squirrel monkeys were tested in larger groups in their home environment.

Effect of coronary blood flow on thallium-201 uptake and washout

Myocardial uptake and washout of thallium-201 (201TI) were studied in an experimental dog model in which regional blood flow to the posterior wall was varied by transient 2-minute occlusion of the circumflex coronary artery to produce transient ischemia and reactive hyperemia. Thallium-201 myocardial activity in a region of interest was determined continuously after i.v. administration by a gamma camera and computer program. Activity in the posterior wall was compared with that in the anterior wall in the same dog and the posterior wall of control dogs. Thallium-201 uptake was directly related to blood flow. With reactive hyperemia, there was a rapid and absolute increase in uptake followed by rapid washout; with ischemia, there was slow and decreased uptake followed by a slow washout. The calculated myocardial activity during washout in both ischemic and hyperemic areas approached values in control dogs long after blood flow had returned to baseline levels. Significant differences in washout slopes were found between the three groups of dogs (-0.156%/min in control dogs, -0.244%/min after reactive hyperemia, and -0.076%/min after transient ischemia, with half-washout times of 5.3 hours, 3.4 hours and 11.0 hours, respectively). These data suggest that both the initial decrease in activity in the ischemic area and the initial excess in the hyperemic area are corrected by different washout rates of ischemic and hyperemic cells during redistribution.

Functional evaluation of coronary collateral development in conscious dogs

Gradual coronary constriction was elicited in conscious dogs by means of an implanted ameroid coronary constrictor. The functional state of the coronary collateral circulation was serially evaluated by means of regional contractile responses, using brief occlusions of the left circumflex coronary artery and strenuous running in the field. Although resting regional myocardial function was unchanged throughout the study, regional myocardial shortening during coronary occlusion decreased to 9% of control at 3-4 days after the operation; it then recovered progressively to 24% at 7-9 days, 45% at 15-18 days, and 94% at 20-24 days. Concomitantly, reactive hyperemia measured with a flowmeter declined from 300% at 3-4 days to 228, 88, and 0% at 7-9, 15-18, and 20-24 days, respectively. A bout of running held 21 days after the ameroid implant when resting regional function was well maintained induced severe regional and global dysfunction. These findings indicate the usefulness of regional myocardial contractile responses in assessing coronary collateral reserve.

Regional left ventricular wall thickness early and late after coronary occlusion in the conscious dog

Regional wall thickness and endocardial segment lengths in normal and ischemic zones of the left ventricle were measured simultaneously with ultrasonic-dimension gauges before and after chronic circumflex artery occlusion in conscious dogs. After 3 wk, end-diastolic segment lengths (EDL) in normal zones increase 10% (P less than 0.01), shortening increased 22% (P less than 0.05), and end-diastolic wall thickness (EDWT) was reduced by 12.8% (P less than 0.01). In ischemic zones at 3 wk, EDL was reduced by 15.4% (P less than 0.01), and subendocardial shortening recovered slightly to 15% of control; EDWT increased 11% at 3 days postocclusion and thereafter remained near control values (change not significant), but systolic wall thickening improved substantially, reaching 38% of control at 3 wk. Thus, tissue loss and slight return of function occurred in the ischemic subendocardium, whereas overall wall function (as reflected by regional wall thickening) improved considerably over time. These findings suggest that recovery of function in the outer layers of the wall after myocardial infarction modifies the close correlation between regional subendocardial segment and wall thickening dynamics observed acutely.