Increased coronary venous inorganic phosphate concentrations during experimental myocardial ischemia

Association of serum phosphate and changes in serum phosphate with 28-day mortality in septic shock from MIMIC-IV database

This study aimed to investigate the relationship between serum phosphate levels, changes in serum phosphate levels, and 28-day mortality in patients with septic shock. In this retrospective study, data were collected from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database between 2008 and 2019. Patients were divided into three groups according to the tertiles of serum phosphate levels. Kaplan-Meier curves and log-rank test analyses were used for survival analysis. Multivariate logistic regression, and restricted cubic spline (RCS) curve were used to explore the association between serum phosphate, delta serum phosphate levels and 28-day mortality. In total, 3296 patients with septic shock were included in the study, and the 28-day mortality was 30.0%. Serum phosphate levels were significantly higher in the non-survivor group than in the survivor group. The Kaplan-Meier curves showed significant differences among the three groups. Multivariate logistic regression analysis and the RCS curve showed that serum phosphate levels were independently and positively associated with the 28-day mortality of septic shock. Non-survivors had higher delta serum phosphate levels than survivors. Survival analysis showed that patients with higher delta serum phosphate levels had higher 28-day mortality. A non-linear relationship was detected between delta serum phosphate and 28-day mortality with a point of inflection at - 0.3 mg/dL. Serum phosphate levels were positively and independently associated with 28-day mortality in septic shock. Delta serum phosphate level was a high-risk factor for patients with septic shock.

ICU-Admission Hyperphosphataemia Is Related to Shock and Tissue Damage, Indicating Injury Severity and Mortality in Polytrauma Patients

Hyperphosphataemia can originate from tissue ischaemia and damage and may be associated with injury severity in polytrauma patients. In this retrospective, single-centre study, 166 polytrauma patients (injury severity score (ISS) ≥ 16) primarily requiring intensive care unit (ICU) treatment were analysed within a five-year timeframe. ICU-admission phosphate levels defined a hyperphosphataemic (>1.45 mmol/L; n = 56) opposed to a non-hyperphosphataemic group (n = 110). In the hyperphosphataemic group, injury severity was increased (ISS median and IQR: 38 (30–44) vs. 26 (22–34); p < 0.001), as were signs of shock (lactate, resuscitation requirements), tissue damage (ASAT, ALAT, creatinine) and lastly in-hospital mortality (35.7% vs. 5.5%; p < 0.001). Hyperphosphataemia at ICU admission was shown to be a risk factor for mortality (1.46–2.10 mmol/L: odds ratio (OR) 3.96 (95% confidence interval (CI) 1.03–15.16); p = 0.045; >2.10 mmol/L: OR 12.81 (CI 3.45–47.48); p < 0.001) and admission phosphate levels alone performed as good as injury severity score (ISS) in predicting in-hospital mortality (area under the ROC curve: 0.811 vs. 0.770; p = 0.389). Hyperphosphataemia at ICU admission is related to tissue damage and shock and indicates injury severity and subsequent mortality in polytrauma patients. Admission phosphate levels represent an easily feasible yet strong predictor for in-hospital mortality.

Changes in Serum Fibroblast Growth Factor 23 in Patients With Acute Myocardial Infarction

BACKGROUND

Fibroblast growth factor 23 (FGF23) induces cardiac remodeling. We investigated the changes in serum FGF23 levels in patients diagnosed with acute myocardial infarction (AMI).Methods and Results:A total of 44 patients diagnosed with AMI were included in the current study. All patients underwent emergency percutaneous coronary intervention (PCI). The median of peak creatine kinase (CK) and CKMB values was 1,816 U/L and 159 U/L, respectively. Serum levels of FGF23, calcium, and inorganic phosphate (iP) were measured before PCI, and on days 1, 3, 5, 7 after PCI. Serum FGF23 levels showed a slight, but significant decrease on days 1 and 3 after PCI, and a 1.5- and 2.0-fold increase on days 5 and 7, respectively, after PCI. As compared with propensity score-matched patients without AMI, serum FGF23 was significantly lower among the current cohort of AMI patients. In 22 subjects who underwent a follow-up echocardiographic examination at 6 months after the onset of AMI, the log-transformed relative increase in FGF23 on day 7 significantly and negatively correlated with changes between LVEF on admission and that at 6 months afterward.

CONCLUSIONS

After a slight decrease on days 1 and 3 after admission, serum FGF23 increased significantly on days 5 and 7. The underlying mechanism and potential clinical importance of these observations require further investigation.

Hyperkalemia in neonatal diarrheic calves depends on the degree of dehydration and the cause of the metabolic acidosis but does not require the presence of acidemia

Hyperkalemia is a clinically important electrolyte imbalance in neonatal diarrheic calves that has previously been associated with skeletal muscle weakness and life-threatening cardiac arrhythmias. The aim of the present retrospective analysis was to identify risk factors for hyperkalemia in a convenience sample of 832 calves (≤ 21 d of age) with a clinical diagnosis of diarrhea admitted to a veterinary teaching hospital. Plasma potassium concentrations were most closely associated with parameters of dehydration and renal function such as serum creatinine [Spearman correlation (rs) = 0.61], urea (rs = 0.51), and inorganic phosphorus concentrations (rs = 0.64). Plasma potassium concentrations were weakly associated with venous blood pH (rs = -0.21). Although venous blood pH was not predictive in a multivariate linear regression analysis, the odds of having hyperkalemia (>5.8 mmol/L) in acidemic calves was found to be 8.6 times as high as in nonacidemic calves [95% confidence interval (CI): 4.8-15.4]. However, the presence of hyperkalemia depended on the nature of an existing acidosis, and the odds for the presence of hyperkalemia in acidemic calves with hyper-D-lactatemia (>3.96 mmol/L) were only 0.15 times as high as in acidemic calves with normal D-lactate concentrations (95% CI, 0.11-0.22). Acidemia in hyperkalemic diarrheic calves was associated with hyponatremia and increased concentrations of inorganic phosphorus, L-lactate, and unidentified strong anions that presumably included uremic anions such as sulfate. We conclude that hyper-D-lactatemia in neonatal diarrheic calves is not usually associated with elevated plasma potassium concentrations. Application of the simplified strong ion acid-base model indicated that dehydration is an important contributor to the pathogenesis of hyperkalemia and acidemia in neonatal calves with diarrhea.

Metabolic response to prolonged reduction of myocardial blood flow distal to a severe coronary artery stenosis

Limited data are available concerning the effects of mild-to-moderate, sustained reductions of coronary blood flow on myocardial aerobic metabolism. This study tested the hypothesis that a sustained flow reduction distal to a severe coronary artery stenosis may be well tolerated (after the initial insult is passed) because of gradual improvement in the balance between myocardial oxygen supply and demand. Studies were performed in eight sedated, closed-chest domestic swine that were instrumented with an artificial coronary arterial stenosis (80% diameter reduction). Hemodynamics, regional myocardial blood flow and oxygen, lactate, acid, and base metabolism were measured before stenosis and at 5, 20, 60, 120, and 180 minutes after stenosis insertion. Regional myocardial function (ultrasonic length sensors) was measured serially during 2 hours in three additional swine. After stenosis placement, endocardial and transmural flows declined (p less than 0.05) compared with flows before stenosis (from 1.54 +/- 0.37 to 0.73 +/- 0.24 ml/min/g [mean +/- SD] and from 1.44 +/- 0.31 to 1.19 +/- 0.25 ml/min/g, respectively). Thereafter, flows remained unchanged for the duration of the study. Similarly, prestenosis heart rate (135 +/- 7 beats/min), aortic mean pressure (113 +/- 17 mm Hg), and tension time index (27.1 +/- 3.6 mm Hg.sec) remained constant for the duration of the study. In contrast, regional coronary venous pH declined (p less than 0.05) compared with prestenosis levels (7.35 +/- 0.02) 5 minutes after stenosis (7.28 +/- 0.04), but it returned to prestenosis levels during the next hour. Regional coronary venous PCO2 exhibited a similar pattern (i.e., acute increase during poststenosis with gradual return to prestenosis levels).(ABSTRACT TRUNCATED AT 250 WORDS)

Lactate metabolism in acute myocardial infarction and its relation to regional ventricular performance

Myocardial metabolism was assessed in 20 patients with acute anterior myocardial infarction using lactate uptake (defined as (aortic lactate - great cardiac venous lactate)/aortic lactate X 100) as an index. The regional ejection fraction of the anterior wall was obtained from left ventriculography. There was a linear relation between lactate uptake and regional ejection fraction (r = 0.79, p less than 0.001). Four patients without total occlusion in the infarct vessel had a higher lactate uptake (19.6 +/- 6.7 versus 4.2 +/- 13.4%, p less than 0.05) and regional ejection fraction (26.3 +/- 7.9 versus 14.9 +/- 7.0%, p less than 0.05) than did 16 patients with total occlusion. The latter group of patients underwent intracoronary infusion of urokinase, which resulted in reperfusion in 13 patients. Lactate uptake before urokinase infusion (sample I), just after reperfusion (sample II), 30 minutes after reperfusion (sample III) and 4 weeks after reperfusion (sample IV) was 5.7 +/- 13.2, -13.9 +/- 14.7, 2.9 +/- 15.2 and 20.2 +/- 11.0%, respectively (sample I versus II and II versus III, p less than 0.01; sample I versus IV and III versus IV, p less than 0.05). The decrease in lactate uptake immediately after reperfusion, which was accompanied by an increase in creatine kinase-MB isoenzyme release into the blood, was considered to be the result of a "washout" effect. Lactate uptake was ameliorated 4 weeks later, accompanied by an improvement (from 15.1 +/- 7.1 to 23.4 +/- 7.2%, p less than 0.01) in the regional ejection fraction. It is concluded that the degree of asynergy was closely related to the extent of metabolic deterioration in myocardial infarction.

Quantification of ischemic stress during repeated coronary artery occlusion in the dog. A method for validation of therapeutic effects. II. Reproducibility of the release and uptake of electrolytes and substrates

As criterion for the degree of ischemic stress on myocardium during repeated coronary artery occlusion, the reproducibility of the release of potassium, lactate and inorganic phosphate in the early reperfusion period was examined. On 20 anaesthetized open-chest mongrel-dogs, local ischemia was induced by intermittent occlusion of the LAD artery. In each experiment the artery was occluded for 3 min 4 to 6 times with intervals of 45 min. Just before beginning, at the end of occlusion and after 5 min of reperfusion, arterial and coronary venous blood was collected simultaneously. Additionally, 3 ml of blood were withdrawn by syringe-pumps during the first minute of reperfusion. Intra-individually, the following standard-deviations were found in a representative experiment with 5 occlusions: potassium +/- 7% (22.62 +/- 1.6 mumol/min); inorganic phosphate +/- 9% (19.82 +/- 2.06 mumol/min); lactate +/- 11% (55.38 +/- 5.93 mumol/min). Interindividually, the correlation between the release of these markers and the perfusion bed of the ligated artery led to coefficients of about r approximately 0.88. On an average, per gram ischemic tissue/wet weight 0.74 mumol potassium, 0.6 mumol inorganic phosphate and 1.98 mumol lactate were released. The ratios between the releases remained constant independent of the size of ischemic area. An even closer correlation with coefficients of about r approximately 0.97 was found between the O2-debt in the occlusion period. Based on a synoptic assessment of metabolic and energetic parameters, this experimental model may render more detailed information on pharmacological interventions during ischemic stress.

Metabolic basis for disorders of purine nucleotide degradation

Purine nucleotide degradation refers to a regulated series of reactions by which human purine ribonucleotides and deoxyribonucleotides are degraded to uric acid in humans. Two major types of disorders occur in this pathway. A block of degradation occurs with syndromes involving immune deficiency, myopathy or renal calculi. Increased degradation of nucleotides occurs with syndromes characterized by hyperuricemia and gout, renal calculi, anemia or acute hypoxia. Management of disorders of purine nucleotide degradation is dependent upon modifying the specific molecular pathology underlying each disease state.

Some factors affecting phosphate transport in a perfused rat heart preparation

Pi uptake by a perfused rat heart preparation did not require the presence of any other permeant anion, but was markedly dependent on the extracellular Na+ concentration and accelerated when tissue oxygenation was inadequate. Pi efflux was also independent of other permeant anions, but apparently varied with the intracellular Na+ concentration. Cardiac Pi efflux was not sensitive to a number of inhibitors that clock Cl- movement in heart and other tissues. Both uptake and efflux apparently proceed via a reversible electroneutral co-transport system linked to the transmembrane Na+ gradient. Pi uptake was independent of cardiac work load, but the efflux rate was sharply accelerated after an increase in aortic pressure development, with a slow return towards basal values during sustained periods of high work output. An inverted biphasic effect on the efflux rate was observed after a reduction in cardiac work load. Mild hypoxia and respiratory and metabolic acidosis each resulted in a transient acceleration of Pi efflux followed by a return towards basal values during prolonged exposure to the stimulus, whereas respiratory and metabolic alkalosis produced a similar but inverted response. The origin of these phasic effects on Pi efflux remains to be identified at present.

The evaluation of ischemic heart disease thallium-210 with comments on radionuclide angiography

Coronary artery disease causing myocardial ischemia and infarction is the leading cause of death in America. Methods that can be used to diagnose and follow the response to therapy of coronary artery disease or its effect on myocardial ischemia should help control the morbidity and mortality of ischemic heart disease. The use of ECG monitoring is less sensitive and specific for ischemia than thallium (TI) imaging or the use of radionuclide angiography (RNA). In large patient populations, the findings of a positive ECG and TI or RNA study will be highly predictive for the presence of coronary artery disease, while negative test results make the disease unlikely. A combined approach to the patient with possible ischemic heart disease is presented.

Analysis of rat heart in vivo by phosphorus nuclear magnetic resonance

High-resolution 31P nuclear magnetic resonance spectra at 73.83 MHz are reported for rat heart in vivo. In live rats, it was possible to observe the cardiac content of ATP, phosphocreatine, and Pi. Only a small amount of whole-blood 2,3-diphosphoglycerate was observed in the spectra, precluding the possibility that blood phosphate compounds were masking the spectra of cardiac phosphate compounds. The 31P nuclear magnetic resonance spectra of in vivo and perfused rat hearts were similar and support the utilization of the perfused rat heart as a model system for studying high-energy phosphate metabolism of the heart in vivo. The dynamic flux of high-energy phosphate compounds was investigated by subjecting the rat to respiratory arrest. In this experiment, the heart followed the classic metabolic pattern known to occur during cardiac arrest; phosphocreatine and then ATP decreased in concentration while Pi increased in concentration. The 31P nuclear magnetic resonance analysis of rat heart in vivo is demonstrated to be a practical and feasible method for studying cardiac high-energy phosphate metabolism.

Release of nucleosides from canine and human hearts as an index of prior ischemia

During ischemia, myocardial adenosine triphosphate is degraded to adenosine, inosine and hypoxanthine. These nucleosides are released into coronary venous blood and may provide an index of ischemia; adenosine may also participate in the autoregulation of coronary flow. In dogs, the temporal relations between reactive hyperemic flow and nucleoside concentrations in regional venous blood were correlated after brief occlusions of a segmental coronary artery. Reactive hyperemia and adenosine release peaked together in 10 seconds, persisted for 10 to 30 seconds and then decreased in a pattern consistent with the hypothesis that they are related. During initial reflow after 45 seconds of ischemia, mean concentrations of adenosine, inosine and hypoxanthine increased, respectively, to 52, 67 and 114 nmol/100 ml plasma; after 5 minutes of ischemia, the respective levels increased to 58, 1,570 and 1,134 nmol and fell quickly. In nine patients there was a similar release of nucleosides into coronary sinus blood during reperfusion after 59 to 80 minutes of ischemic arrest during cardiac surgery. With initial reflow, adenosine, inosine and hypoxanthine levels reached 65, 655 and 917 nmol/100 ml of blood, respectively. Inosine and hypoxanthine concentrations remained high for 5 to 10 minutes after cardiac beating resumed, often when production of lactate had decreased. The results indicate that postischemic release of nucleosides reaches significant levels in man as well as animals, is parallel with the duration of ischemia, is temporary and may be a useful supplement to measurement of lactate as an index of prior myocardial ischemia.

Myocardial metabolism in cyanotic congenital heart disease studied by arteriovenous differences of lactate, phosphate, and potassium at rest and during atrial pacing

To study myocardial metabolism in chronic hypoxia due to cyanotic congenital heart disease, coronary arteriovenous differences of lactate (L), pyruvate (P), inorganic phosphate (Pi) and potassium (K) were measured in 14 cyanotic patients and seven controls, at rest and during atrial pacing. At rest, there was no difference in any parameter between cyanotic and noncyanotic patients. During atrial pacing (150-175/min) for 10 min, a moderate drop in L-extraction occurred in the control patients with some increase in L/P ratio in coronary venous blood. Cyanotic patients fell into two groups: in nine (group I), the arterial oxygen saturation (SaO2) dropped with pacing. Their L-extraction fell sharply, from 28.1 +/- 3.12 to --2.8 5.51 and L production occurred in five. There was a significance increase in coronary venous L/P ratio. Five cyanotic patients (group II) showed no drop in SaO2 with pacing, and L extraction as well as L/P ratio remained stable. Uptake of Pi was noted in all patients at rest, during pacing this disappeared in controls and group I cyanotics but not in group II. No K changes were seen in any patient. Thus, myocardial metabolism is normal at rest in patients with cyanotic CHD; during atrial pacing, a shift toward anaerobic metabolism occurs if SaO2 drops; cyanotic patients whose SaO2 remains stable appear to withstand pacing better than controls.

Methylprednisolone treatment in acute myocardial infarction. Effect on regional and global myocardial function

The effects of methylprednisolong treatment on acute myocardial ischemia were studied in nine closed chest dogs. After 1 hour of proximal occlusion of the left anterior descending coronary artery, an intravenous bolus injection (50 mg/kg body weight) of methylprednisolone was administered and its effects studied during an additional 2 hours of occlusion. After 2 hours of treatment the following significant mean alterations from levels after 1 hour of occlusion were noted: an increase of 16.7% in heart rate and decreases of 23% in left ventricular end-diastolic pressure, 32% in stroke volume, 14% in cardiac output and 37% in stroke work. Peak systolic pressure, maximal rate of rise of left ventricular pressure (dP/dt), left ventricular end-diastolic volume, systemic vascular resistance and coronary sinus blood flow changed less than 10%. Ejection fraction and regional cardiac wall motion were not improved. Metabolic dysfunction of the coronary-occluded myocardium, revealed by regional lactate as well as potassium derangements, persisted throughout the 2 hour treatment period. Comparison of these results with equivalent data from an untreated series of nine dogs with 3 hours of occlusion demonstrated no improvement in the treated series. Methylprednistone failed to restore regional cardiac metabolic and mechanical function, and treatment was associated with a further rise in S-T segment elevations. Administration of methylprednisolone after 1 hour of proximal left anterior descending coronary occlusion apparently does not reverse cardiac dysfunction in the first 2 hours of treatment.

Characterization of the ischemic process by regional metabolism

The myocardial cell requires energy for contractile activity and for the work of internal maintenance. With the onset of ischemia mechanical performance is compromised. If the ischemia is severe and persistent, the energy necessary to maintain the internal millieu proves inadequate and cell death ensues. Ischemic heart disease is a regional phenomenon with normal and abnormal cell metabolism occurring side by side. The ischemic cell demonstrates hemodynamic, electrical and biochemical instability; its passage from a state of reversible to irreversible injury may persist for as long as 7 days and offers an opportunity to introduce interventions that may protect it and reduce ultimate infarct size. There is as yet no adequate objective means for predicting the mass of infarcted tissue. However, studies of regional metabolism, if properly conducted, may help define the adequacy of coronary vascular reserve and characterize the ischemic process. Current techniques utilize a myocardial pacing stress to induce an ischemic response. Although virtually every metabolic pathway is disrupted by severe ischemia, the assay of selected metabolities in arterial and coronary venous blood samples has provided information of diagnostic significance.

Changes in coronary venous inosine concentration and myocardial wall thickening during regional ischemia in the pig

Correlations between local mechanical and metabolic events were studied during a partial decrease in flow in the left anterior descending coronary artery in 14 open-chest pigs. A decrease in flow to 28% (19-39%) of the control value was achieved with an adjustable screw clamp. A flow probe was placed around the artery. Blood samples were taken from the regional anterior coronary vein and the femoral artery. Myocardial wall thickening was measured with a harpoon type of mercury strain gauge. During ischemia, systolic myocardial wall thickening decreased to 44.5 ± 5.1% ( SE ) of its control value ( P < 0.001). The mean concentrations of plasma potassium and whole blood inosine, hypoxanthine, and lactate in three serial 2-minute samples obtained during a 6-minute control period were compared with those obtained during a 6-minute period of partial occlusion. During ischemia, venous inosine concentration increased from 10.9 ± 0.7 µ M to 18.5 ± 1.8 µM ( P < 0.005), venous hypoxanthine concentration increased from 28.5 ± 1.4 µ M to 33.0 ± 1.5 µ M ( P < 0.005), venous potassium concentration increased from 3.77 ± 0.10 m M to 4.08 ± 0.13 m M ( P < 0.001), and venous lactate concentration increased from 1.04 ± 0.19 m M to 1.52 ± 0.17 m M ( P < 0.001). The arterial level of potassium increased very little. The arterial concentration of the other compounds did not change significantly during the 6-minute period of ischemia. Myocardial lactate extraction changed from a control value of 42.6 ± 6.7% to -4.6 = 12.5% ( P < 0.05). A negative correlation ( r s = -0.79, P < 0.01) was observed between venous inosine concentration and myocardial wall thickening (percent of control) during ischemia. This study indicates that the local venous inosine concentration is a sensitive indicator of regional myocardial ischemia in the pig.

Release of adenosine from human hearts during angina induced by rapid atrial pacing

This study was designed to determine whether human hearts release adenosine, a possible regulator of coronary flow, during temporary myocardial ischemia and, if so, to examine the mechanisms involved. Release of adenosine from canine hearts had been reported during reactive hyperemia following brief coronary occlusion, and we initially confirmed this observation in six dogs hearts. Angina was then produced in 15 patients with anginal syndrome and severe coronary atherosclerosis by rapid atrial pacing during diagnostic studies. In 13 of these patients, adenosine appeared in coronary sinus blood, at a mean level of 40 nmol/100 ml blood (SE = +/-9). In 11 of these 13, adenosine was not detectable in control or recovery samples; when measured, there was concomitant production of lactate and minimal leakage of K(+), but no significant release of creatine phosphokinase, lactic acid dehydrogenase, creatine, or Na(+). THERE WAS NO DETECTABLE RELEASE OF ADENOSINE BY HEARTS DURING PACING OR EXERCISE IN THREE CONTROL GROUPS OF PATIENTS: nine with anginal syndrome and severe coronary atherosclerosis who did not develop angina or produce lactate during rapid pacing, five with normal coronaries and no myocardial disease, and three with normal coronaries but with left ventricular failure. The results indicate that human hearts release significant amounts of adenosine during severe regional myocardial ischemia and anaerobic metabolism. Adenosine release might provide a useful supplementary index of the early effects of ischemia on myocardial metabolism, and might influence regional coronary flow during or after angina pectoris.