Ischaemic myocardial damage in chronic renal failure

Evaluation of the Heart and Great Vessel Calcification by Conventional Computed Tomography in Hemodialysis Patients

Heart diseases are responsible for death in hemodialysis patients. The aim of this study was to determine whether we can assess the degree of calcification of the heart and great vessels in hemodialysis patients by non-gated conventional computed tomography (CT) without contrast media. Thirty patients were included in the present study. The hemodialysis group comprised 15 patients and the age-matched control group comprised 15 patients without hemodialysis or cardiac diseases who underwent CT scanning. Axial cross-sectional images were taken from the aortic arch to the diaphragm to detect calcification of the aorta and coronary arteries. Eleven patients in the hemodialysis group showed calcification in 1.9 +/- 1.4 coronary vessels, a frequency significantly greater than that of the 0.3 +/- 0.2 coronary vessels in the control group (p < 0.01). Fourteen patients in the hemodialysis group showed calcification of the aorta with a mean score 9.7 +/- 7.2, significantly greater than mean score in the control group (3.5 +/- 2.2; p < 0.01). These results suggest that we can assess an increase in the incidence of calcification of the coronary arteries and the aorta by conventional CT scanning without contrast media in patients undergoing hemodialysis.

Amplification of atherosclerotic calcification and Mönckeberg's sclerosis: a spectrum of the same disease process

Autopsy studies have shown the near universal presence of fatty streaks and fibroatheromas in the general population from which chronic kidney disease (CKD) patients arise. The vast majority of CKD patients have multiple conventional cardiovascular risk factors. Atherosclerosis, once present, can predominantly manifest as medial calcification, which has been previously termed Mönckeberg's sclerosis. This term has also been used in rare cases to describe vascular calcinosis not related to CKD. This clarification is critical to advance the field in terms of pathological diagnosis and treatment of CKD bone and mineral disorder. Factors that appear to promote the osteoblastic transformation of vascular smooth muscle cells and enhance deposition of calcium hydroxyapatite crystals include phosphorus activation of the Pit-1 receptor, bone morphogenic proteins 2 and 4, leptin, endogenous 1,25 dihydroxy vitamin D, vascular calcification activating factor, and measures of oxidative stress. These entities work to accelerate the atherosclerotic process in CKD patients and may be future targets for diagnosis and treatment. Although conventional atherosclerotic risk factors should be optimally managed, it should be noted that trials of hydroxymethylglutaryl-CoA reductase inhibitors have failed to attenuate the rate of progressive vascular calcification as measured by computed tomography scans.

Accelerated atherosclerotic calcification and Monckeberg's sclerosis: a continuum of advanced vascular pathology in chronic kidney disease

Autopsy studies have demonstrated the near universal presence of fatty streaks and fibroatheromas in the general population from which patients with chronic kidney disease (CKD) arise. The vast majority of patients with CKD have multiple conventional cardiovascular risk factors. Vascular atherosclerotic calcification develops in most patients as they transition from the general population to significant CKD as part of cholesterol crystallization within atherosclerotic lesions. Once present, however, atherosclerotic medial calcification can become prominent and has been previously identified as Mönckeberg's sclerosis. A unifying concept supported by the preponderance of pathologic evidence contends that Mönckeberg's sclerosis is a manifestation of accelerated atherosclerosis in patients with CKD. The term has also been used in rare cases to describe vascular calcinosis not related to CKD. This clarification is critical to advance the field in terms of pathologic diagnosis and treatment of CKD bone and mineral disorder. Factors that seem to promote the osteoblastic transformation of vascular smooth muscle cells and enhance deposition of calcium hydroxyapatite crystals include phosphorus activation of the Pit-1 receptor, bone morphogenic proteins 2 and 4, leptin, endogenous 1,25 dihydroxyvitamin D, vascular calcification activating factor, and measures of oxidative stress. These entities work to accelerate the atherosclerotic process in patients with CKD and may be future targets for diagnosis and treatment because randomized trials with hydroxymethylglutaryl-CoA reductase inhibitors have failed to attenuate the rate of progressive vascular calcification.

Emergencies in continuous dialysis patients: diagnosis and management

The number of patients undergoing long-term hemodialysis and peritoneal dialysis is growing in the United States. To provide adequate emergent care to these patients emergency physicians must understand the alterations in normal physiologies present in these patients and how this may affect care. Cardiovascular disease and infection (especially Staphylococcus aureus sepsis) are the leading causes of death among dialysis patients. These patients are also subject to a significantly higher incidence of life-threatening electrolyte disturbances, particularly hyperkalemia and hypercalcemia, than the general population. Suicide, cardiac tamponade, intracranial hemorrhage, bleeding disorders, and bowel infarction are also much more frequent. The inability of dialysis patients to excrete drugs, metabolites, toxins, and fluids significantly alters their responses to common emergencies and should directly influence their care. Failure to recognize these differences in physiology may result in the use of standard forms of emergency therapy that may compound, rather than treat, the underlying disorder. Although most dialysis patients who come into an emergency department have conditions that can, and should, be managed by their nephrologist, the presence of a life threatening emergency requires prompt, appropriate therapy by the emergency physician.

Serum magnesium level and arterial calcification in end-stage renal disease

In this paper we examine the relationship of serum levels of Ca, P, Ca X P, P/Mg, Ca X P/Mg, alkaline phosphatase, and iPTH to the development or regression of peripheral arterial calcifications (AC) in 44 patients with end-stage renal disease being treated by continuous ambulatory peritoneal dialysis (CAPD). The average follow-up time of this longitudinal study was 27 months (range 6-67 months). The patients were divided into two groups: Group A, those showing one or more increases of AC; and Group B, patients in whom AC either did not develop or decreased during the follow-up. There was no significant difference in serum Ca, P, Ca X P, alkaline phosphatase of iPTH between the two groups. However, serum Mg was significantly lower in Group A than in Group B (2.69 +/- 0.52 and 3.02 +/- 0.51 mg/dl, respectively, P less than 0.001), while the ratios P/Mg and Ca X P/Mg were significantly higher. Our observations suggest that in end-stage renal disease hypermagnesemia may retard the development of arterial calcifications.

Haemodialysis does not affect the pharmacokinetics of nifedipine

To establish dosage recommendations in patients with end-stage renal disease undergoing chronic haemodialysis, nifedipine kinetics were studied between and during haemodialysis sessions. In eight patients, during the interdialytic period, peak plasma concentrations of nifedipine (29-332 ng/ml) were reached 0.5-1.0 h after administration of a single 10 mg oral dose. Elimination half-life and oral plasma clearance were respectively 2.6 +/- 0.5 h and 1 176 +/- 412 ml/min. Nifedipine plasma protein binding was decreased in uraemic patients (88.8 +/- 0.3% vs 94.4 +/- 0.1%) but not affected by haemodialysis. Removal by haemodialysis was low: the dialyser extraction ratio and the dialysis clearance were respectively 2.3 +/- 0.8% and 2.8 +/- 0.9 ml/min.

Effect of hemodialysis on left ventricular function. Dissociation of changes in filling volume and in contractile state

Prior studies of the effect of hemodialysis on left ventricular function have not distinguished between the removal of uremic toxins and the change in cardiac filling volume. To separate these effects, left ventricular function was examined by serial echocardiography in five stable hemodialysis patients before and after three different dialysis procedures: (a) hemodialysis with volume Loss, (b) ultrafiltration (volume loss only), and (c) hemodialysis without volume loss. The patients were similarly studied under control conditions and after increased (5 degrees of head-down tilt for 90 min) and decreased (lower body negative pressure) cardiac filling volume. After hemodialysis with volume loss, end-diastolic volume (EDV) decreased from 167 to 128 ml (P less than 0.001) and end-systolic volume (ESV) decreased from 97 to 51 ml (P less than 0.001) without a change in stroke volume (SV). Ejection fraction increased from 42 to 52% (P less than 0.001) and mean velocity of circumferential fiber shortening (VCF) increased from 0.61 to 1.04 circumferences (circ)/s (P less than 0.001). After ultrafiltration, EDV decreased from 167 ml to 124 ml (P less than 0.001) and SV from 73 ml to 39 ml (P less than 0.001), without significant changes in ESV or VCF. In contrast to the maneuvers in which volume loss occurred, after hemodialysis without volume loss ESV decreased from 95 to 66 ml (P less than 0.001) and SV increased from 74 ml to 97 ml (P less than 0.001) without changes in EDV. EF increased from 44 to 59% (P less than 0.001) and VCF increased from 0.64 to 1.26 circ/s (P less than 0.001). Ventricular function curves plotted from data obtained under conditions of altered cardiac filling volume before and after the three dialysis maneuvers demonstrate that ultrafiltration produced a pure Frank-Starling effect, while hemodialysis with or without volume loss produced a shift in the ventricular function curves, which demonstrated an increase in the contractile state of the left ventricle. The changes in left ventricular function produced by regular hemodialysis are the combined effects of a decrease in EDV and an increase in the contractile state of the left ventricle.

Chronic alcoholic cardiomyopathy: fact or fiction?

This study was designed to ascertain whether excessive prolonged alcohol intake itself may produce chronic cardiomyopathy. We reasoned that, since alcoholic cardiomyopathy is allegedly a chronic condition, asymptomatic or early symptomatic cases should be found in a large hospitalized alcoholic population. Two groups of patients were studied. The first group consisted of 292 chronic alcoholics whose hospital records were examined for evidence of early cardiomyopathy, according to predetermined criteria. The second group consisted of eight patients who died on the medical service ward and in whom one of the diagnoses listed in the autopsy report was alcoholic cardiomyopathy. In the first group hepatic and neurological complications of alcoholism were frequent; no patient was found to have early cardiomyopathy. In the second group the post-mortem records indicated that all eight patients had other illnesses causing the abnormal findings on which the diagnosis of alcoholic cardiomyopathy was made. We conclude that the concept of chronic alcoholic cardiomyopathy caused by the direct toxic effect of alcohol may not be valid.

Left ventricular function in chronic renal failure

Left ventricular function was studied in 14 patients with end-stage chronic renal failure using non-invasive methods (echocardiography and systolic time intervals). Patients were divided into 3 groups. Group 1 consisted of 5 patients who were normotensive at the time of study and group 2 of 7 patients who were hypertensive when studied. Group 3 consisted of 2 patients: one was receiving propranolol and the other, studied 302 days after renal transplantation, was receiving digitalis for recurrent episodes of cardiac failure. All except the patient receiving propranolol had normal left ventricular function in systole with normal measurements of fractional fibre shortening (% delta S, EF) and normal measurements relating to the velocity of ventricular contraction (mean Vcf, mean velocity of posterior wall motion). Stroke volume and cardiac output were normal in some patients but were increased in patients with fluid overload. Early diastolic compliance of the left ventricle seemed to be normal except in the patient with recurrent cardiac failure. The study provided no evidence for the existence of a specific uraemic cardiomyopathy.