The clinical utility of radionuclide ventriculography in cardiac transplantation

To assess ventricular function in patients who have undergone cardiac transplantation, 247 radionuclide ventriculograms were performed on 94 patients. During the first three days after transplantation, 19% demonstrated left ventricular dysfunction and 41% showed isolated right ventricular dysfunction. In 95 cases, radionuclide ventriculography was performed within 24 hr of myocardial biopsy. A reduction in left ventricular ejection fraction to less than 50% was significantly more common with moderate-severe rejection than with mild rejection. In six instances in which there was discordance between ventriculography and biopsy, radionuclide ventriculography proved particularly useful: three cases showed severe left ventricular dysfunction despite only mild rejection by biopsy, and three cases with ventricular dysfunction from rejection were missed by the initial biopsy. Thus, radionuclide ventriculography can provide functional data in transplant patients that is complementary to myocardial biopsies since biopsy grade is a poor predictor of left ventricular function and biopsy can miss significant rejection.

Nonuniformity in myocardial accumulation of fluorine-18-fluorodeoxyglucose in normal fasted humans

In initial studies using fluorine-18-fluorodeoxyglucose (FDG) in normal fasted subjects, we observed disparities in the regional myocardial accumulation of this tracer. Accordingly, we systematically evaluated regional myocardial FDG accumulation in comparison with regional myocardial perfusion assessed with oxygen-15-water and oxidative metabolism assessed with carbon-11-acetate in nine normal subjects (four studied after a 5-hr fast and five studied both fasted and following glucose loading). Under fasting conditions, myocardial accumulation of FDG in the septum and anterior wall averaged 80% of that in the lateral and posterior walls (p less than 0.03). In contrast, after glucose loading the regional distribution of myocardial FDG accumulation became more homogeneous. Regional myocardial perfusion, oxidative metabolism, and accumulation of carbon-11-acetate were homogeneous under both conditions. Thus, under fasting conditions there are regional variations in myocardial accumulation of FDG, which are visually apparent, are not associated with concomitant changes in oxidative metabolism or perfusion, and cannot be attributed to partial-volume effects. This significant heterogeneity may limit the specificity of PET with FDG for detecting myocardial ischemia in fasting subjects.

The in vivo availability of gentamicin when admixed with total nutrient solutions: a comparative study

The relative in vivo availability of gentamicin when administered by two different intravenous methods was evaluated in patients treated in a surgical intensive care unit in a randomized, prospective, crossover study. Each patient received gentamicin therapy via intravenous piggyback (IVPB) and in-line burette (ILB) methods. In the IVPB method, the drug was mixed in 5% dextrose in water (D5W) and infused intermittently. In the ILB method, the drug was mixed using the patient's total nutrient admixture (TNA) solution as the diluent in an ILB, which was inserted between the TNA bottle and its administration set and infused intermittently. A serial sampling of four sets of serum concentrations of the gentamicin was obtained. Pharmacokinetic parameters (Kel, Vd, and a maximum serum concentration) were calculated from the four sets of concentrations collected per patient. The IVPB method yielded mean values of Kel, Vd, and C1.5mg/kg of 0.13 hr-1, 0.39 liter/kg, and 5.1 micrograms/ml, respectively. The ILB method yielded mean values of Kel, Vd, and C1.5mg/kg of 0.14 hr-1, 0.34 liter/kg, and 5.6 micrograms/ml, respectively. A t-test for paired samples was applied to these mean values. Significant difference was not found (p greater than 0.05). The intermittent infusion of gentamicin, using TNA as the diluent and an ILB, produced equivalent serum concentrations when compared with D5W as the diluent.

The clinical role of radionuclide imaging in cardiac transplantation

Cardiac transplantation is developing into a routine therapy with widespread availability. Nuclear medicine studies play an important role in evaluating potential transplant recipients and in providing documentation of the severity of ventricular dysfunction and the presence of ischemic but viable myocardium. Nuclear cardiology has increased our knowledge of the physiology of cardiac transplants and is now playing an increasing adjunctive role in management. Radionuclide ventriculography performed early after transplantation can identify patients both with abnormal biventricular function resulting from preservation injury and with isolated right ventricular dysfunction. It also provides important functional data that complements the cardiac biopsy in allograft rejection. New techniques such as 111In antimyosin antibodies and 111In lymphocytes have potential value for the accurate, noninvasive diagnosis of rejection. PET promises to improve the ability to diagnose coronary atherosclerosis of the allograft.

Negative endocrine control system for inflammation in rats

Inflammatory processes may be suppressed by endogenous mechanisms such as release of adrenocorticosteroid hormones through stimulation of the hypothalamus-pituitary-adrenal axis. In the present study, the relationship between the temporal development of carrageenan-induced edema in the hindlimb of the rat and release in plasma of the principal endogenous adrenocorticosteroid of the rat corticosterone was investigated. Suplantar injection of carrageenan produced a biphasic increase in basal plasma corticosterone levels that was not attributed to diurnal variation. The plasma level of corticosterone increased rapidly after injection of carrageenan and peaked 12-fold at 20 min. This first phase increase was attributed to the stress of the injection since it was mimicked by subplantar injection of saline. The second phase of corticosterone release was gradual and peaked 12-fold 7 hr after injection of carrageenan. The second phase was not elicited by subplantar injection of saline. When the hypothalamus-pituitary-adrenal axis is impaired via hypophysectomy, carrageenan-induced edema is more intense and lasts longer than in control rats. The results demonstrate that adrenocorticosteroid hormones are released as a result of the stress of injection and by the inflammatory response. Release of adrenocorticosteroids acts as a feedback mechanism to suppress the inflammatory response.

Tc-99m white cell scintigraphy in suspected acute infection

The usefulness of In-111 labeled white cells in acute infection is well documented but the role of Tc-99m labeled white cell scintigraphy (WCS) has not been as clearly established. Using stannous fluoride colloid and a simple labelling procedure with 20 ml of autologous whole blood, three cases are presented in which Tc-99m WCS established unexpected diagnoses in patients who had remained undiagnosed despite extensive investigation.

End-systolic elastance as an evaluation of myocardial function in shock

The response of the heart during sepsis has been studied in human and animal models with disparate results. Because sepsis induces marked peripheral vascular changes, to accurately determine the cardiac response, one must use indices of cardiac performance that are independent of loading conditions and heart rate. The slope of the end-systolic pressure-diameter relationship (ESPDR) has been proposed to have these properties. Pigs were equipped with transducers to measure left ventricular pressure, internal short axis diameter (D), and pulmonary and coronary artery blood flows. After 7-10 days of basal observations, an endotoxin-loaded osmotic pump delivering endotoxin at 10 micrograms/kg/hr was implanted into each pig. Fourteen pigs were so treated, and 4 expired before 24 hr of endotoxin challenge. In the surviving pigs, cardiac output, heart rate, dP/dtmax, and peak systolic pressures were elevated. However, both ESPDR and % D shortening were both significantly depressed. These data suggest that the cardiac response to chronic endotoxin challenge includes a loss of inotropic state as indicated by the load-insensitive indicator, ESPDR, and confirmed by depressed % D shortening. One possible mechanism for reduced inotropic state during endotoxin challenge could be the loss of coronary perfusion. The surviving endotoxin-challenged pigs demonstrated a significant increase in coronary perfusion while stroke work remained unchanged, suggesting that depressed cardiac inotropic state during endotoxin challenge was not caused by reduced coronary blood flow. Rather, the myocardium was relatively overperfused. Another possible mechanism for the loss of cardiac inotropism during endotoxin challenge may be endotoxin-induced generation of reactive oxygen free radicals. This possibility was tested by measuring total cardiac gluthathione, a cellular component depleted by oxidant stress. Endotoxemia reduced these levels 50%. These results suggest that cardiac injury may be mediated by the generation of reactive oxygen free radicals. Further study will determine if this mechanism participates in the loss of cardiac inotropism during endotoxin challenge.

Relation between myocardial glutathione content and extent of ischemia-reperfusion injury

The relation between the extent of myocardial injury sustained during reperfusion and total glutathione (GSH) content in the ischemic myocardium was examined in anesthetized open-chest pigs subjected to coronary occlusion for 45 minutes and reperfusion for 2 hours. In pigs infused with saline during reperfusion (n = 6) there was a decrease in myocardial GSH content from 380 +/- 48 micrograms/g in normally perfused myocardium to 182 +/- 36 micrograms/g in the ischemic reperfused myocardium (p less than 0.02). Myocardial infarct size (expressed as a percentage of the ischemic area) was 12.5 +/- 0.8%. There was a delay of recovery of contractile function before returning to 60% of preocclusion value. In pigs pretreated with buthionine sulfoximine (BSO) (n = 5), an inhibitor of cellular GSH synthesis, there was reduction in GSH content to 215 +/- 25 micrograms/gm in normally perfused myocardium and to 77 +/- 8 micrograms/gm in the ischemic reperfused myocardium. The extent of injury was greater as evidenced by an increase in infarct size to 30.4 +/- 4.0% (p less than 0.001), severe destructive changes in subepicardial ultrastructure, which were absent in saline-infused pigs, and persistence of dyskinesia throughout reperfusion. In pigs infused with glutathione intravenously (0.8 gm/kg) at a rate of 6.5 mg/kg/min (n = 6), 5 minutes before and continuously during reperfusion, there was an increase in GSH content to 582 +/- 67 micrograms/g in normally perfused myocardium and to 312 +/- 80 micrograms/g in ischemic reperfused myocardium. The increase in myocardial GSH was associated with a reduction in infarct size to 7.5 +/- 1.3% (p less than 0.05, compared with saline-infused pigs) and an early recovery of contractile function of the ischemic myocardium. GSH infusion into pigs pretreated with BSO (n = 4) failed to increase myocardial GSH content and failed to reduce the extent of myocardial injury. Thus, the extent of myocardial injury sustained during reperfusion is very dependent on the effectiveness of its antioxidant defenses. Markedly increased susceptibility to injury occurs when the GSH content in the ischemic myocardium becomes depleted.

Variation in end-systolic pressure-diameter relationship using dP/dtmin or P/Dmax as a definition of end-systole in chronic endotoxemic pigs

We have reported that cardiac inotropism is reduced in various shock states, most recently during chronic endotoxemia (Lee et al.: American Journal of Physiology 254:H324-H330, 1988) [1]. We based this conclusion upon the alterations observed in the slope of the end-systolic pressure-diameter relationship (ESPDR). Recently, Dietrick and Raymond (Dietrick and Raymond: Surgical Infection Society, 7th Annual Meeting, May, 1987, p 83) [2] have reported that the slope of the end-systolic pressure-wall thickness relationship was augmented in the early stages of sepsis and depressed immediately prior to expiration. One major difference between our studies is the definition of end-systole; we used the time when the ratio of pressure-to-diameter (P/D) in the left ventricle is maximal (P/Dmax), whereas they used the time when the first derivative of pressure is minimal (dP/dtmin). In order to determine if the discrepancy between our conclusions could be explained by the differing definitions of end-systole, data from previous studies were reanalyzed, and the slope of the pressure-diameter relationship at P/Dmax and at dP/dtmin was calculated. Pigs were equipped with instruments to measure left ventricular pressure, short axis diameter, and ECG. Observations during the basal state were obtained 3-7 days after surgery. Chronic endotoxemia was induced by intravenous infusion of S. enteriditis endotoxin via an osmotic minipump at 10 micrograms/kg/hr. During the basal state, the value for the slope of ESPDR at dP/dtmin was lower than the value for the slope of ESPDR at P/Dmax, and there was a good correlation between the two values. During chronic endotoxemia, the slope of ESPDR at dP/dtmin did not change. However, the slope of ESPDR at P/Dmax decreased significantly suggesting that chronic endotoxemia reduced cardiac inotropism. This conclusion is supported by the findings that chronic endotoxemia reduced steady-state values of percentage diameter-shortening (an estimate of ejection fraction) and stable stroke work at significantly higher end-diastolic diameter. These data indicate that it is possible to calculate differing slopes of ESPDR from the same observations dependent upon the time during the cardiac cycle chosen as end-systole. More importantly, these data suggest that during chronic endotoxemia, ventricular relaxation dynamics may change so that postsystolic shortening becomes more prominent and therefore higher values for the slope of ESPDR using pressure and diameter values at dP/dtmin can be calculated.

Normalised radionuclide measures of left ventricular diastolic function

Abnormal left ventricular diastolic function is being increasingly recognised in patients with clinical heart failure and normal systolic function. A simple routine radionuclide measure of diastolic function would therefore be useful. To establish this, the relationship of peak diastolic filling rate (normalized for either end diastolic volume, stroke volume, or peak systolic emptying rate), and heart rate, age, and left ventricular ejection fraction was studied in 64 subjects with normal cardiovascular systems using routine gated heart pool studies. The peak filling rate, when normalized to end diastolic volume, correlated significantly with heart rate, age and left ventricular ejection fraction, whereas normalization to stroke volume correlated significantly to heart rate and age but not to left ventricular ejection fraction. Peak filling rate normalized for peak systolic emptying rate correlated with age only. Multiple regression equations were determined for each of the normalized peak filling rates in order to establish normal ranges for each parameter. When using peak filling rate normalized for end diastolic volume or stroke volume, appropriate allowance must be made for heart rate, age and ejection fraction. Peak filling rate normalized to peak ejection rate is a heart rate independent parameter which allows the performance of the patient's ventricle in diastole to be compared with its systolic function. It may be used in patients with normal systolic function to serially follow diastolic function or if age corrected, to screen for diastolic dysfunction.

Myocardial salvage with streptokinase combined with nitroglycerine and verapamil in acute myocardial infarction

We tested the hypothesis that preservation of left ventricular function results from treatment with intravenous streptokinase given in the first 2 hours from onset of acute transmural myocardial infarction together with nitroglycerine and verapamil. Thirty-three consecutive patients with onset of pain less than 2 hours prior to admission, received intravenous streptokinase 1.5 x 10(6) units with intravenous nitroglycerine and verapamil; 23 concurrently admitted "control" patients with pain onset 2-4 hours received intravenous nitroglycerine and verapamil only. Radionuclide ventriculographic assessment at 2 days revealed a significantly greater left ventricular ejection fraction in the streptokinase-treated patients (54.5 +/- 2.8 vs 46.1 +/- 2.9; P less than 0.05), which persisted at 28-35 days (50.1 +/- 2.3 vs 41.2 +/- 2.9; P less than 0.05). Streptokinase-treated patients had a significantly increased incidence of ischaemic events in the 35 days following infarction, but a lower incidence of death, congestive cardiac failure and non-fatal ventricular tachycardia than control group patients. Infarct-related artery patency assessed at 3-5 days was 94% in streptokinase-treated patients. We conclude that early presentation and treatment with intravenous streptokinase, nitroglycerine and verapamil is associated with a high incidence of successful thrombolysis and significant preservation of left ventricular function. Nitroglycerine and verapamil may augment the efficacy of streptokinase in this group of patients.

Cardiac function and coronary flow in chronic endotoxemic pigs

We have reported that myocardial inotropism was depressed in acute and chronic endotoxemia. One possible mechanism for this observation is that endotoxemia reduces myocardial perfusion and indeed, we observed reduced myocardial perfusion in acute endotoxemia. This study tested the hypothesis that reduced inotropism of chronic endotoxemia was accompanied by reduced coronary artery blood flow. Fifteen pigs were equipped with left atrial and ventricular catheters, circumflex coronary and pulmonary artery flow meters, left ventricular pressure transducer, and ultrasonic crystals in the anterior-posterior axis to measure internal short axis diameter by sonomicrometry. The pigs recuperated for 3 days before basal data were collected over the next 3-5 days. After at least 7 postoperative days, an osmotic pump containing Salmonella enteriditis endotoxin was implanted in 12 pigs. Endotoxin was delivered at 10 micrograms/hr/kg for 2 days, at which time the animals were sacrificed. Osmotic pumps containing sterile saline were implanted in 3 pigs. Eight of the 12 endotoxemic pigs survived; 4 died before the morning of the second day. The survivors exhibited elevated heart rate, peak left ventricular systolic pressure, and cardiac output. Inotropism was evaluated by calculating the slope of the end-systolic pressure-diameter relationship (ESPDR) and % diameter-shortening. ESPDR was significantly depressed on the second endotoxemic day, while % diameter-shortening was depressed on both endotoxemic days. Coronary artery blood flow was significantly elevated on both endotoxemic days, while cross-sectional stroke work was unchanged. Therefore, the ratio of coronary blood flow to stroke work increased on both endotoxemic days. Nonsurvivors exhibited reduced heart rate, cardiac output, peak left ventricular systolic pressure, ESPDR, and % diameter-shortening. Neither coronary artery blood flow nor flow-to-work ratios increased in this group. Sham endotoxemic pigs demonstrated no cardiac or hemodynamic changes over 3 days. These results indicate that depressed inotropism during chronic endotoxemia was not caused by reduced coronary blood flow; rather, the myocardium was relatively overperfused.

Abnormal proteins as the trigger for the induction of stress responses: heat, diamide, and sodium arsenite

Thermotolerance and synthesis of heat shock proteins are induced in cells in response to a variety of environmental stresses. We examined the suggestion of Hightower (1980) that modifications of intracellular proteins may be the triggering event that induces heat shock protein synthesis and thermotolerance. We did so by modifying cellular proteins, using diamide, a sulfhydryl oxidizing agent, and dithio-bis (succinimidyl propionate), an agent that cross-links bifunctional amino groups. Both of these agents induced heat shock proteins and thermotolerance in CHO (HA-1) cells. Furthermore, we observed cross-resistance and self-tolerance with three seemingly unrelated stimuli (diamide, heat, and sodium arsenite). This observation suggests that the induction of protective responses to these stimuli is mediated by a common mechanism. The results support the hypothesis that production of abnormal proteins by various stresses induces the stress responses as well as tolerance.

Fine structure and permeability of the metacercarial cyst wall of Clinostomum marginatum (Digenea)

Encysted metacercariae of Clinostomum marginatum (Digenea) were obtained from tissues of yellow perch, Perca flavescens. The outermost wall (host response) as seen under electron microscopy consisted of a single, fibrous tissue layer, 10-25 micron thick. The tissue contained flattened fibrocytes, small fat deposits, and vacuoles embedded between layers of collagen fibers. The cyst cavity was filled with small vesicles, crystals, and debris. No layer corresponding to the primary (parasite-produced) cyst wall secreted by most species of metacercariae was noted. To determine the permeability of the cyst wall, encysted worms were incubated under initial rate conditions with [3H] glucose, with and without the glucose transport inhibitors phlorizin and phloretin. After incubation, the worms were mechanically excysted, washed, and processed to determine glucose uptake rates. Vmax and Kt were greater than those obtained for worms excysted prior to incubation with substrate. Moreover, the presence of phlorizin or phloretin in the incubation medium had no effect on glucose uptake by encysted worms. Thus, the selective permeability of the cyst wall permits free diffusion of glucose to the cutaneous transport systems of the worm, while restricting the movements of phlorizin and phloretin.