Effect of hyperparathyroidism on cardiac function in patients with end-stage renal disease

Extraskeletal effects of vitamin D

The presence of vitamin D receptors in diverse tissues like immune cells, beta-cells in the pancreas, and cardiac myocytes has prompted research to evaluate the impact of vitamin D deficiency on the occurrence of immune diseases, diabetes, and cardiovascular disease (CVD). The expression of receptors not only in normal cells, but also in cancer cells including breast, prostate, and colon cancer cells has moreover opened the path to therapeutic exploitation of vitamin D or its metabolites and hypocalcemic structural analogues as pharmaceutical tools in the fight against chronic non-communicable diseases like diabetes, CVD, and cancer.

Changes in the QT intervals, QT dispersion, and amplitude of T waves after hemodialysis

BACKGROUND

Increased QT dispersion (QTd) has been associated with an increased risk for ventricular arrhythmias and sudden death in the general population and in various clinical states.

METHODS

We investigated the impact of hemodialysis (HD) on QT, QTd, and T-wave amplitude in subjects with end-stage renal failure. Data on 49 patients on chronic HD were studied. The QT, QTd, and the sum of amplitude of T waves (SigmaT) in millimetre in the 12 ECG leads, along with a host of other ECG parameters, body weight, blood pressure, heart rate, electrolytes, and hemoglobin/hematocrit were measured before and immediately after HD.

RESULTS

QT decreased (380.9 +/- 38.4-363.5 +/- 36.8 ms, P = 0.001), the QTc did not change (406.2 +/- 30.8-405.4 +/- 32.2 ms, P = 0.8), the QTd increased (31.3 +/- 14.6-43.9 +/- 18.6 ms, P = 0.003), and the SigmaT decreased (32.3 +/- 15.7-25.9 +/- 12.6 mm, P = 0.0001) after HD. There was no correlation between the change in QTd and the changes in serum cations, heart rate, the subjects' weight, T-wave duration, and SigmaT. However, the change in QTc correlated inversely with the change in serum Ca(++) (r =-0.339, P = 0.021).

CONCLUSION

QTd increased, the SigmaT decreased, and the QTc and T-wave duration remained stable, after HD. The QTd increase, although may be real, could also reflect measurement errors stemming from the decrease in the amplitude of T waves (as shown recently), imparted by HD; this requires clarification, to use QTd in patient on HD.

Cardiac performance and morphology in end-stage renal disease

Patients with end-stage renal disease (ESRD) experience a variety of hemodynamic and metabolic abnormalities that predispose to alterations in cardiac performance and morphology. High cardiac output related to renal anemia, hypertension, volume overload, and the arteriovenous fistula (in patients on hemodialysis) predispose to eccentric left ventricular (LV) hypertrophy. Hypertension, aortic stiffness, and aortic stenosis predispose to concentric LV hypertrophy. Most ESRD patients have a hybrid form of LV hypertrophy. LV hypertrophy is commonly accompanied by LV diastolic dysfunction. LV systolic dysfunction is less common. Newer dialytic techniques, excellent control of hypertension, and correction of renal anemia produce regression of LV hypertrophy. The effect of these interventions on LV systolic and diastolic function is less well established. Alterations in serum calcium, choice of dialysate base, hypoxia, and comorbid conditions may influence the effects of dialysis (particularly hemodialysis) on LV function. A variety of negative inotropic drugs may depress LV function in patients with ESRD.

Marked improvement of left ventricular function after parathyroidectomy in a hemodialysis patient with secondary hyperparathyroidism and left ventricular dysfunction

A 52-year-old woman, a hemodialysis patient, was admitted because of exertional dyspnea. Echocardiography showed left ventricular (LV) dilatation and reduced contraction. Coronary angiography showed no fixed stenosis. She had elevated levels of parathyroid hormone (PTH) as a result of secondary hyperparathyroidism with advanced renal failure. After parathyroidectomy, marked improvement of LV function following immediate decrease of blood levels of PTH was observed. It is suggested that PTH might have a significant role in the pathogenesis of LV dysfunction and that parathyroidectomy might be effective as a therapy for heart failure in some patients with secondary hyperparathyroidism and LV dysfunction.

Homocysteine and cardiovascular disease: current evidence and future prospects

Hyperhomocysteinemia is an independent risk factor for cardiovascular disease. Despite the well-known effectiveness of vitamin supplementation in reducing homocysteine levels, it is not known whether lowering of homocysteine levels is associated with a reduction in cardiovascular morbidity and mortality. The aim of this review is to discuss the epidemiologic evidence about the relation between homocysteine and cardiovascular disease, the pathophysiologic mechanisms responsible for the deleterious vascular and hemostatic effects of homocysteine, and studies of the potential benefits of homocysteine-lowering therapy.

Parathormon, calcium, phosphorus, and left ventricular structure and function in normotensive hemodialysis patients

Clinical and experimental data suggest that Parathormon (PTH), calcium, and phosphorus participate in left ventricular hypertrophy (LVH) and affect myocardial contractility in end-stage renal disease. Cellular calcium overload and interstitial fibrosis induced by PTH may lead to impairment of left ventricular diastolic function. Hyperphosphatemia is an independent risk of cardiovascular mortality in dialysis patients. The aim of the study was to estimate the influence of PTH and calcium-phosphorus metabolism on left ventricular structure and function in hemodialysis patients, without hypertension and antihypertensive drug therapy (SBP = 126.2 +/- 11.1 DBP = 75.8 +/- 6.5 mmHg). Echocardiographic findings in a group of 22 normotensive HD patients had been compared to 43 hypertensive HD patients. Relationships between PTH, calcium-phosphorus metabolism and echocardiography in normotensive group were then evaluated. Left ventricular mass index (LVMI) was lower in normotensive patients: 128.3 +/- 46.2 versus 165.8 +/- 46.7 (p < 0.01). The prevalence of LVH was 55% in normotensive HD patients compared to 86% in hypertensive group (p < 0.01). In normotensive group we found correlation between PTH and LVMI (r = 0.44; p < 0.05). There were also significant relationships between calcium and posterior wall thickness (r = -0.44; p < 0.05), phosphorus and LVMI (r = 0.47; p < 0.05). A significant correlation was observed between both phosphorus, calcium x phosphorus product and E/A ratio: r = -0.47 and r = -0.43, respectively (p < 0.05 both). Disturbances of calcium-phosphorus metabolism and secondary hyperparathyroidism contributes to left ventricular hypertrophy, and impaired left ventricular diastolic function in normotensive hemodialysis patients.

Pathophysiology of cardiovascular disease in hemodialysis patients

Cardiovascular disease is the principal cause of morbidity and mortality in dialysis patients. The principal alterations responsible are left ventricular hypertrophy and arterial disease characterized by an enlargement and hypertrophy of arteries and the high prevalence of atheromatous plaques. Left ventricular hypertrophy is the consequence of combined effects of chronic hemodynamic overload and nonhemodynamic biochemical and neurohumoral factors characteristic of uremia. The hemodynamic overload is due to flow and pressure overload. The flow overload is tightly related to hyperkinetic circulation caused by anemia, arteriovenous fistula, or overhydration and is characterized by an enlargement of the left ventricular cavity. The pressure overload in these patients is more tightly related to abnormal geometry and function of large conduit arteries, principally the stiffening of arterial tree. The flow overload is also in large part responsible for remodeling of arterial tree, and as the heart and vessels are a coupled interactive physiological system, cardiac and vascular alterations occur in parallel, being induced to a great extent by the same hemodynamic abnormalities. The principal clinical consequences of left ventricular hypertrophy and arterial alterations are heart failure, ischemic heart disease, and peripheral artery disease. Cardiovascular alterations are only partly reversible, and efforts should be directed toward early prevention.

Increased QT interval dispersion after hemodialysis: role of peridialytic electrolyte gradients

Chronic renal failure patients on maintenance hemodialysis (HD) have a number of ECG abnormalities and cardiac arrhythmias. Clinical and experimental data have shown that increased QT dispersion is associated with severe ventricular arrhythmias and sudden cardiac death. Therefore, the aim of this study was to investigate whether the uremic patients receiving long-term HD have increased QTc interval and/or QTc dispersion compared to normal subjects and to evaluate the effect of electrolyte changes between the predialysis and postdialysis phases on these parameters. Forty patients with end-stage renal failure on long-term HD (22 men, 18 women, mean age 44 years) were included in this study. Serum concentrations of K+, Na+, Ca++, Mg++, Cl-, phosphate, urea, creatinine, HCO3-, and arterial blood gases (PO2, PCO2), together with blood pH, were monitored and QTc intervals and QTc dispersion were measured from 12-lead ECG in predialysis and postdialysis phases. The hemodialyzed patients had an increased predialysis QTc maximum interval and QTc dispersion compared to normal subjects (480 +/- 51 vs 310 +/- 38 msec, p < 0.001 and 61 +/- 17 vs 42 +/- 14 msec, p < 0.001, respectively). Both QTc maximum interval and QTc dispersion increased significantly at the end of the HD (480 +/- 51 vs 505 +/- 49 msec p < 0.001 and 61 +/- 17 vs 86 +/- 18 msec, p < 0.001, respectively). The serum K+ (5.3 +/- 0.56 vs 3.36 +/- 0.41 mEq/L, p < 0.001), phosphate (7.19 +/- 1.62 vs 3.81 +/- 1.02 mg/dL, p < 0.001), magnesium (0.87 +/- 18 vs 0.75 +/- 0.14 mg/dL) and urea concentrations (174 +/- 22 vs 74 +/- 14 mg/dL, p < 0.001) significantly decreased, whereas the Ca++ (2.21 +/- 0.18 vs 2.47 +/- 0.24 mg/dL, p < 0.001), HCO3- (15.5 +/- 3.2 vs 20.1 +/- 3.4 mmol/L, p<0.001) concentrations and pH (7.27 +/- 1.1 vs 7.43 +/- 1.2, p < 0.001) significantly increased after HD compared to predialysis values. There was significant correlation between the QT dispersion increase and serum electrolyte changes (K+, Ca++, and pH levels) (p < 0.05). The association between serum electrolyte changes, acid-base status and QT measurements might provide new insights into the evaluation of the ionic bases involved in inhomogeneous ventricular repolarization.

Association of hyperphosphataemia with haemodynamic disturbances in end-stage renal disease

BACKGROUND

Because recent data demonstrated that the shortened survival and excess cardiovascular death of end-stage renal disease (ESRD) patients are predicted by hyperphosphataemia, we examined the haemodynamic alterations associated with high serum phosphorus levels in ESRD patients on haemodialysis.

METHODS

Sixty-six ESRD patients were studied. Patients were separated arbitrarily into two groups, i.e. with predialysis serum phosphate <2 mmol/l ('normal' phosphate) and, serum phosphate >2 mmol/l ('high' phosphate). Cardiac and arterial function and structure were analysed by computer-assisted ultrasonography.

RESULTS

Hyperphosphataemic patients were characterized by higher diastolic and mean blood pressures (P<0.05), and higher cardiac index (P<0.001) caused by an increased stroke index (P<0.05) and higher heart rate (P<0.01). The cardiac work index was significantly increased in patients with higher phosphate levels (P<0.01). Hyperphosphataemic patients tended to have a higher common carotid artery diameter (P=0.07), but similar carotid artery intima-media thickness, and lower carotid wall-to-lumen ratio (P<0.05) than patients with 'normal' serum phosphorus. As a result of lower wall-to-lumen ratio in the presence of higher mean blood pressure, the carotid tensile stress was higher in hyperphosphataemic ESRD patients (P<0.05).

CONCLUSION

These findings suggest that, in stable ESRD patients, hyperphosphataemia is associated with increased BP, hyperkinetic circulation, increased cardiac work, and high arterial tensile stress. These haemodynamic abnormalities could favour the development of cardiovascular complications and contribute to high cardiovascular morbidity and mortality.

Parathyroid hormone, vitamin D, and cardiovascular disease in chronic renal failure

BACKGROUND

Parathyroid hormone and vitamin D have been shown to influence cardiac and vascular growth and function experimentally in human subjects with normal renal function. Because of the increased prevalence of hyperparathyroidism and altered vitamin D status in chronic renal failure, these alterations have been considered to contribute to the increased prevalence of cardiovascular disease and hypertension seen in this patient population. Methods and Results. In this article, we review experimental and clinical literature on the cardiovascular effects of parathyroid hormone and vitamin D and relate them to the development of cardiac and vascular dysfunction in uremia, such as: cardiomyopathy, myocardial hypertrophy, and fibrosis, as well as to myocardial ischemia; uremic glucose intolerance, dyslipidemia, and atherosclerosis; hypertension; and vascular and cardiac calcifications.

CONCLUSIONS

The hyperparathyroid state and altered vitamin D status found in uremia contribute to the cardiovascular pathology seen clinically in uremia and also to the excess mortality from cardiovascular causes found in this patient group. The therapeutic implications of these observations are also discussed.

QT dispersion in patients with end-stage renal failure and during hemodialysis

Interlead variability of the QT interval in surface electrocardiogram (ECG), i.e., QT dispersion, reflects regional differences in ventricular recovery time, and it has been linked to the occurrence of malignant arrhythmias in different cardiac diseases. The purpose of the study was to assess the effect of hemodialysis on QT and corrected QT (QTc) interval and dispersion in chronic hemodialyzed patients. Data of 34 nondiabetic patients (male/female = 21/13; mean age, 54 +/- 15 yr) on chronic hemodialysis were studied. Polysulfone capillaries and bicarbonate dialysate containing (in mEq/L) 135 Na+, 2.0 K+, 1.5 Ca2+, and 1.0 Mg2+ were used. Simultaneous 12-lead ECG were recorded before and after hemodialysis in a standard setting. The QT intervals for each lead were measured manually on enlarged (x3) ECG by one observer using calipers. Each QT interval was corrected for patient heart rate: QTc = QT/square root of RR (in milliseconds [ms]). The average cycle intervals were 853 +/- 152 ms predialysis and 830 +/- 173 ms postdialysis; the difference was not significant. The maximal QT interval changed significantly from 449 +/- 43 to 469 +/- 41 ms (P < 0.01). The corrected maximal QT interval increased significantly from 482 +/- 42 to 519 +/- 33 ms (P < 0.01). The QT dispersion changed from 56 +/- 15 to 85 +/- 12 ms (P < 0.001) and the corrected QT interval dispersion from 62 +/- 18 to 95 +/- 17 ms (P < 0.001). During hemodialysis, the serum potassium and phosphate levels decreased from 5.5 +/- 0.8 to 3.9 +/- 0.5 (mM) and from 2.3 +/- 0.5 to 1.6 +/- 0.4 (mM), respectively, whereas calcium increased from 2.2 +/- 0.23 to 2.5 +/- 0.22 (mM). It is concluded that hemodialysis increases the QT and QTc interval and QT and QTc dispersion in patients with end-stage renal failure. Thus, it may be stated that the nonhomogeneity of regional ventricular repolarization increases during hemodialysis. Measurement of QT and QTc dispersion is a simple bedside method that can be used for analyzing ventricular repolarization during hemodialysis.

Intravenous calcitriol regresses myocardial hypertrophy in hemodialysis patients with secondary hyperparathyroidism

To evaluate the response of circulating intact parathyroid hormone (iPTH) on myocardial hypertrophy in hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT), echocardiographic and neurohormonal assessments were performed over a 15-week period in 15 HD patients with SHPT before and after calcitriol treatment and 10 HD control patients with SHPT not receiving calcitriol therapy. We prospectively studied a group of 15 patients with significantly elevated iPTH levels (iPTH >450 pg/mL) receiving calcitriol (2 microg after dialysis twice weekly). Clinical assessment, medication status, and biochemical and hematological measurements were performed once a month. Throughout the study, calcium carbonate levels were modified to maintain serum phosphate levels at less than 6 mg/dL, but body weight, antihypertensive medication, and ultrafiltration dose remained constant. In patients treated with calcitriol, an adequate reduction of iPTH levels was found (1,112 +/- 694 v 741 +/- 644 pg/mL; P < 0.05) without changes in values of serum ionized calcium (iCa++), phosphate, or hematocrit. Blood pressure (BP), cardiac output (CO), and total peripheral resistance (TPR) did not significantly change. After 15 weeks of treatment with calcitriol, M-mode echocardiograms showed pronounced reductions in interventricular wall thickness (13.9 +/- 3.6 v 12.8 +/- 3.10 mm; P = 0.01), left ventricular posterior wall thickness (12.5 +/- 2.4 v 11.3 +/- 1.8 mm; P < 0.05), and left ventricle mass index (LVMi; 178 +/- 73 v 155 +/- 61 g/m2; P < 0.01). However, in control patients, these changes were not found after the treatment period. In addition, sequential measurements of neurohormonal mediator levels in patients receiving calcitriol showed that plasma renin (18.5 +/- 12.7 v 12.3 +/- 11.0 pg/mL; P = 0.007), angiotensin II (AT II; 79.7 +/- 48.6 v 47.2 +/- 45.7 pg/mL; P = 0.001), and atrial natriuretic peptide (ANP; 16.6 +/- 9.7 v 12.2 +/- 4.4 pg/mL; P = 0.03) levels significantly decreased, whereas antidiuretic hormone (ADH), epinephrine, and norepinephrine levels did not change significantly. The percent change in LVMi associated with calcitriol therapy had a strong correlation with the percent change in iPTH (r = 0.52; P < 0.05) and AT II (r = 0.47; P < 0.05) levels. We conclude that the partial correction of SHPT with intravenous calcitriol causes a regression in myocardial hypertrophy without biochemical or hemodynamic changes, such as heart rate, BP, and TPR. The changes in plasma levels of iPTH and, secondarily, plasma levels of neurohormones (especially AT II) after calcitriol therapy may have a key role in attenuating ventricular hypertrophy in SHPT.

Autonomic neuropathy predisposing to arrhythmias in hemodialysis patients

Arrhythmias are frequent among the dialysis population and can cause symptoms of palpitations or dizziness. Since autonomic disturbances are known to cause an increased arrhythmogenic stimulus, we questioned whether the presence of central autonomic neuropathy increased the frequency of arrhythmias as identified by 24-hour electrocardiographic monitoring in dialysis patients. Seventy-one patients were randomly chosen from patients established on dialysis in two centers. The mean age of the patients was 71.3 years (median age, 67 years) and median duration on dialysis was 17.0 months (range, 1 to 175 months). Four patients had diabetes. Each patient was tested for autonomic control of blood pressure and heart rate, and underwent Holter electrocardiographic monitoring, commencing 30 minutes before dialysis, for a 24-hour period. The tapes were then analyzed for ventricular and atrial rhythm changes. There was a significantly increased incidence of arrhythmias in individuals with abnormal blood pressure responses (P = 0.005), heart rate responses (P = 0.01), and combined blood pressure and heart rate responses (P = 0.004). We conclude that patients with autonomic dysfunction had an increased frequency of arrhythmias during dialysis.

Electrocardiographic abnormalities in patients receiving hemodialysis

We assessed standard 12-lead and Holter electrocardiographic (ECG) abnormalities in maintenance hemodialysis (HD) patients. Of 221 outpatients receiving HD, 143 (65%) had ECG abnormalities. Rates were higher in male, elderly, hypertensive, and diabetic patients than in female, younger, normotensive, and nondiabetic patients. The prevalence of ECG changes correlated inversely with HD duration. Serial ECGs were compared in 87 patients whose average HD duration was 7.5 +/- 2.5 years. Thirty-four patients (39%) showed normal ECGs throughout, 27 (31%) relatively stable abnormalities, 22 (25%) worsening, and 4 (5%) reversion to normal. Age, hypertension, and diabetes are factors related to abnormal ECG findings. Among the 142 Holter recordings from 72 patients, 70 (97%) were basically in sinus rhythm, and 2 (3%) were in atrial fibrillation. The average frequency of supraventricular premature contractions (SVPCs) was 1597 +/- 9725 per 24 hours, and that of ventricular premature contractions (VPCs), 556 +/- 1415. VPCs were multifocal in 9%, in runs in 25%, and early in 1%. In 29 (40%) of recordings, VPCs appeared mainly during and for several hours after HD. ST-T changes were seen in 43 (60%). In 11, ST depression occurred during and a few hours after HD. Patients receiving HD showed diverse ECG abnormalities. Holter ECGs revealed a high incidence of arrhythmias and ST-T changes, which frequently appeared in relation to HD timing.

Usefulness of left ventricular size and function in predicting survival in chronic dialysis patients with diabetes mellitus

To identify patients at high risk for sudden death, a group of stable patients on maintenance dialysis with diabetes mellitus were studied for up to 135 months to determine if there were clinical, laboratory or echocardiographic predictors of high risk. Eighty-two patients on maintenance dialysis who underwent clinical, laboratory evaluation and echocardiography were enrolled and followed for a mean of 25 months for cardiac and noncardiac complications. Thirty-seven patients with normal wall motion and left ventricular (LV) internal diameter had a mean survival of 35.8 months; 28 patients survived greater than 12 months. Seven patients with normal LV wall motion and dilated LV cavities had a mean survival of 45.7 months; 7 patients survived greater than 12 months. Fifteen patients with abnormal LV wall motion and normal internal LV dimensions had a mean survival of 17 months; 7 patients survived greater than 12 months. Twenty-three patients with both abnormal LV wall motion and dilated LV cavities had a mean survival of 7.8 months; 5 patients survived greater than 12 months. Although echocardiographic abnormalities predicted cardiac mortality at 6 and 12 months, the combination of an abnormal standard electrocardiogram at baseline, clinical history of angina pectoris, and prior documented myocardial infarction or congestive heart failure did not. When the study group was divided by mode or duration of dialysis, presence or absence of diabetes, or use of cardioactive drugs, echocardiographic LV wall motion abnormalities remained the most important determinant of survival.

Parathyroid hormone and myocardial performance in dialysis patients

Whether parathyroid hormone (PTH) has a clinically important effect on myocardial performance is unclear. Previous investigations of cardiac function before and after parathyroidectomy have failed to control for ionized calcium, other biochemical parameters, or heart rate and cardiovascular loading conditions. We performed load- and rate-independent measurements of myocardial contractility in seven stable hemodialysis patients before and after surgical parathyroidectomy under identical conditions of blood ionized calcium (Ca2+), electrolytes, pH, PO2, and hematocrit. Mid-molecule PTH decreased from 44 +/- 8 to 2 +/- 1 ng/mL. Aortic systolic and diastolic pressures, left ventricular chamber dimensions, end systolic wall stress, left ventricular contractility at a common level of afterload, and contractile reserve evaluated with dobutamine were similar before and after parathyroidectomy. Thus, PTH appears not to have a direct effect on myocardial contractile state in dialysis patients.

Myocardial calcification and cardiac dysfunction in chronic renal failure

PURPOSE

Myocardial calcium content may have clinical importance in end-stage renal disease (ESRD), but it is difficult to detect during life. Our goal was to assess the effect of myocardial calcium content on left ventricular ejection fraction (LVEF) in uremic patients undergoing dialysis.

PATIENTS AND METHODS

Energy subtraction radiography of the chest was used to measure myocardial calcium content in 43 patients undergoing dialysis, in 32 control subjects, and in nine patients with advanced cardiomyopathy. LVEF and left ventricular end-diastolic dimension were measured by two-dimensional echocardiography. The concentration of parathyroid hormone was measured by radioimmunoassay; calcium-phosphorus product, alkaline phosphatase, and serum bicarbonate were also assessed.

RESULTS

Patients undergoing dialysis had a greater myocardial calcium content than control subjects [262 +/- 15.4 (mean +/- SE) versus 187 +/- 8 mg/cm2, p less than 0.05]. Ten patients with the highest myocardial calcium content (Group I) had the lowest LVEF values and highest left ventricular end-diastolic dimension. Significant inverse linear associations between LVEF and myocardial calcium content (r = -0.425, p = 0.013) and between parathyroid hormone concentration and LVEF (r = -0.352, p = 0.047) were noted. There was no association between parathyroid hormone concentration and myocardial calcium content. Stepwise regression analysis showed a strong positive correlation between myocardial calcium content and calcium-phosphorus product, vascular calcification, race (black), and parathyroidectomy. Similar analysis shows that LVEF was significantly associated with myocardial calcium content, lung calcium, calcium-phosphorus product, and race (black).

CONCLUSION

We suggest that increased myocardial calcium content results from poor calcium and phosphorus control and may be enhanced by parathyroid hormone hyperactivity. Increased myocardial calcium content is strongly associated with myocardial dysfunction in patients undergoing dialysis.

Secondary hyperparathyroidism and cardiac hypertrophy in hemodialysis patients

Echocardiographic assessment of left ventricular function was performed in 66, stable hemodialysis patients and 50 normal controls matched for sex, age and arterial blood pressure. On the basis of bone histology, hemodialysis patients were classified into two groups: (1) patients with normal bone resorption; and (2) patients with active secondary hyperparathyroidism characterized by an increased bone resorption. Left ventricular function of these two subgroups were compared together as well as with the echocardiographic characteristics of normal controls. In comparison with normal controls, hemodialysis patients with normal bone resorption had an increased left ventricular volume (P less than 0.001) and left ventricular mass (P less than 0.001) with a similar left ventricular mass-to-volume ratio. Their systolic arterial pressure--mass-to-volume ratio correlation was similar to that of normal controls, indicating an adequate myocardial hypertrophy. Patients with increased bone resorption had high parathormone and alkaline phosphatase levels; though the left ventricular dilation was similar to that of hemodialysis patients with normal bone resorption, the left ventricular mass was lower (P less than 0.001) and was similar to the left ventricular mass of normal controls. In addition, patients with increased bone resorption had a lower mass-to-volume ratio (P less than 0.001) and their systolic arterial pressure--mass-to-volume ratio correlation exhibited a significant downward shift (P less than 0.001), suggesting an inadequate myocardial hypertrophy. Patients with increased bone resorption and secondary hyperparathyroidism had an increased heart rate, a higher systolic arterial pressure and end-systolic stress. Furthermore, they had an increased velocity of fiber shortening (P less than 0.01) and shorter left ventricular ejection time (P less than 0.001). In summary, present data suggest the possibility that parathormone may exert myocardial effects in hemodialysis patients.