Non-invasive computerised detection of acute coronary occlusion

The goal of this study was to evaluate the role of a computerised, non-invasive ECG method for detecting acute coronary occlusion (ACO). Ninety-five standard ECG leads were recorded, before and during ACO, from 18 patients undergoing balloon angioplasty. ECG amplitude and derivative parameters were calculated for the ORS, ST and T components of the ECG signal, before and during ACO. Results were obtained for each lead. Sensitivity of the standard visual ECG analysis for detecting ACO was 48%, whereas the percentage of conventional ECG changes during baseline was 14%. For the best ECG parameter, the amplitude parameter of the ORS component, sensitivity was 82%, and the percentage of parameter changes during baseline was 20%. The sensitivity for detecting ACO with five of the six ECG parameters studied was greater than that of the standard visual analysis. Ischaemic changes were detected in 4.3 +/- 1.6 leads per patient using the amplitude parameter of the ORS component, whereas, with the standard visual analysis, 2.5 +/- 2.1 leads demonstrated such changes (p<0.001). Results were then summarized per patient. The standard visual ECG analysis detected ACO in 15 of 18 patients (83%), if at least one lead showed ischaemic changes. The computerised analysis detected ACO in all 18 patients using the same criterion. The sensitivity of the computerised method for detecting ACO in the clinical setting of angioplasty was greater than that of the standard visual analysis. It is suggested that the computerised method may be useful for detecting myocardial ischaemia in other clinical settings of acute myocardial ischaemia.

Experimental use of raffinose as an osmotic agent for peritoneal dialysis

Conventional glucose-based solutions for peritoneal dialysis fluids have been shown to raise problems of biocompatibility. We therefore evaluated the ultrafiltration capabilities of raffinose as an alternative osmotic agent in a non-uremic rat model. Animals were divided into four groups and injected intraperitoneally with solutions containing raffinose (4.5%, 345 mOsm/kg; 16.7%, 518 mOsm/kg) or glucose (1.5%, 346 mOsm/kg; 4.25%, 489 mOsm/kg). Data obtained from animals exposed to 16.7% raffinose were excluded because of precipitation of the osmotic agent. Low-osmolality raffinose solution induced higher ultrafiltered volume than the low-osmolality glucose-enriched fluid at 120 minutes of dwelling time. No significant differences were observed in effluent sodium and potassium concentration and protein dialysate-to-plasma (D/P) ratio. The D/P ratio of phosphate was higher in the low-osmolality raffinose-based fluid than in the low-osmolality glucose solution. The osmolality of the solutions was significantly decreased after a dwelling time of 120 minutes. We conclude that 4.5% raffinose is an effective osmotic agent. Total or partial replacement of glucose by raffinose for clinical peritoneal dialysis could be eventually considered after appropriate evaluation of its biocompatibility and general side effects.

Effects of severe hemorrhage on plasma ANP and glomerular ANP receptors

Atrial natriuretic peptide (ANP) plays an important role in blood volume and electrolyte homeostasis in normovolemia and in hypervolemic states. The currently available information on the effects of hypovolemia on plasma ANP is contradictory. Moreover, possible regulation of ANP receptors during severe hemorrhagic hypovolemia has not been investigated. This study evaluated the effects of severe hemorrhage on plasma ANP and on the regulation of glomerular ANP receptor subtypes in anesthetized rats. Constant rate bleeding of 50% of total blood volume within 2 h induced a reproducible shock state characterized by marked decreases in blood pressure, heart rate, and hematocrit and an increase in plasma renin activity and aldosterone. Hemorrhaged rats exhibited a gradual significant increase in plasma ANP from 39.3 +/- 2.9 to 114.7 +/- 20.0 pmol/l 1 h after the bleeding (P < 0.001 from the initial value and P < 0.02 from the final value of sham-shock rats). Hemorrhage induced a significant decrease in total glomerular ANP binding sites (172 +/- 25 vs. 363 +/- 39 fmol/mg protein in hemorrhaged and sham-shock rats, respectively, P < 0.05). This decrease was mainly due to a significant decrease in ANPC receptors (132 +/- 22 vs. 312 +/- 40 fmol/mg protein in hemorrhaged and sham-shock rats, respectively, P < 0.05). Hemorrhage did not change glomerular ANPA receptor density. No significant differences in the affinity of the glomerular receptor subtypes for ANP were detected. Our data indicate that plasma ANP increases after prolonged severe hemorrhage. It is suggested that downregulation of renal ANPC receptors leads to reduced clearance of ANP and contributes to elevation of its plasma level after severe hemorrhage.

Bone scintigraphy in hungry bone syndrome following parathyroidectomy

A 59-yr-old man with chronic renal failure was admitted for evaluation of generalized skeletal pain and frontal bone mass, which was lytic on radiography. Bone scintigraphy demonstrated several foci of moderately increased uptake, without involvement of the skull mass. Radiographs of these lesions were compatible with brown tumors. Serum parathormone level was elevated and CT demonstrated a lower right cervical mass, consistent with parathyroid tumor. Following the removal of the mass and decrease in parathormone levels, the patient suffered from a prolonged period of hypocalcemia and his bone pain worsened. Repeat bone scintigraphy showed an increase in the number and intensity of the areas of focal uptake, consistent with hungry bone syndrome. This flare-up phenomenon is due to an increase in bone metabolism and is an uncommon finding following parathyroidectomy for primary hyperparathyroidism.

Bone loss in patients with chronic renal disease: prediction with quantitative bone scintigraphy with SPECT

PURPOSE

To determine whether quantitative bone scintigraphy (QBS) with single-energy photon emission computed tomography (SPECT) can help predict which patients with chronic renal disease will show bone mineral density (BMD) loss.

MATERIALS AND METHODS

In 18 patients, the percentage of injected dose of technetium-99m methylene diphosphonate per cubic centimeter of bone was measured with QBS SPECT in the lumbar vertebrae and femoral neck. The differences in BMD over an average of 20 months were measured and compared with SPECT measurements. QBS values were also compared with serum bone turnover markers.

RESULTS

There was a negative correlation (r = -.54, P < .05 for the lumbar spine and r = -.60, P < .01 for the femoral neck) between QBS values and bone loss. Positive and negative predictive values, sensitivity, and specificity of QBS for bone loss in the lumbar spine were 78%, 71%, 78%, and 71%, respectively, and in the femoral neck, 82%, 100%, 100%, and 78%, respectively. Differences between predictive values of serum bone turnover markers were not statistically significant.

CONCLUSION

QBS with SPECT enabled prediction of rapid bone loss in patients with renal disease.

Intraperitoneal phosphate administration in hungry bone syndrome

Hypophosphatemia complicating parathyroidectomy for secondary hyperparathyroidism in renal failure is usually corrected by the oral or intravenous routes. We present a case in which those methods of treatment were not possible, and the phosphate was administered intraperitoneally. Phosphate was added as one molar sodium diphosphate solution to the dialysis fluid. In our case the procedure was well tolerated, phosphate blood levels were rapidly corrected, no alterations in calcium, magnesium or other parameters were detected and the patient was discharged in good condition. In selected cases of hungry bone syndrome after parathyroidectomy, intraperitoneal phosphate can be used safely.