Nutritional modulation of parathyroid hormone secretion may influence risk for left ventricular hypertrophy

Clinical, biochemical, and echocardiographic evaluation of neonates with vitamin D deficiency due to maternal vitamin D deficiency

OBJECTIVE

There are a few number of case reports and small-scale case series reporting dilated cardiomyopathy due to vitamin D-deficient rickets. The present study evaluates the clinical, biochemical, and echocardiographic features of neonates with vitamin D deficiency.

PATIENTS AND METHODS

In this prospective single-arm observational study, echocardiographic evaluation was performed on all patients before vitamin D3 and calcium replacement. Following remission of biochemical features of vitamin D deficiency, control echocardiography was performed. Biochemical and echocardiographic characteristics of the present cohort were compared with those of 27 previously published cases with dilated cardiomyopathy due to vitamin D deficiency.

RESULTS

The study included 148 cases (95 males). In the echocardiographic evaluation, none of the patients had dilated cardiomyopathy. All of the mothers were also vitamin D deficient and treated accordingly. Comparison of patients with normocalcaemia and hypocalcaemia at presentation revealed no statistically significant difference between the ejection fraction and shortening fraction, while left ventricle end-diastolic diameter and left ventricle end-systolic diameter were higher in patients with hypocalcaemia. Previously published historical cases were older and had more severe biochemical features of vitamin D deficiency.

CONCLUSION

To the best of our knowledge, in this first and largest cohort of neonates with vitamin D deficiency, we did not detect dilated cardiomyopathy. Early recognition and detection before developing actual rickets and preventing prolonged hypocalcaemia are critically important to alleviate cardiac complications.

Dietary patterns and components to prevent and treat heart failure: a comprehensive review of human studies

Growing evidence has emerged about the role of dietary patterns and components in heart failure (HF) incidence and severity. The objective here is to provide a comprehensive summary of the current evidence regarding dietary patterns/components and HF. A comprehensive search of online databases was conducted using multiple relevant keywords to identify relevant human studies. The Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets have consistently been associated with decreased HF incidence and severity. Regarding specific dietary components, fruit, vegetables, legumes and whole grains appear beneficial. Current evidence suggests that red/processed meats, eggs and refined carbohydrates are harmful, while fish, dairy products and poultry remain controversial. However, there is a notable lack of human intervention trials. The existing but limited observational and interventional evidence from human studies suggests that a plant-based dietary pattern high in antioxidants, micronutrients, nitrate and fibre but low in saturated/trans-fat and Na may decrease HF incidence/severity. Potential mechanisms include decreased oxidative stress, homocysteine and inflammation but higher antioxidant defence and NO bioavailability and gut microbiome modulation. Randomised, controlled trials are urgently required.

A Review of Plant-based Diets to Prevent and Treat Heart Failure

Evidence supporting the role of nutrition in heart failure (HF) incidence and severity is growing. A comprehensive search of online databases was conducted using relevant keywords to identify human studies including diet and HF. Several plant-based diets have consistently been associated with decreased HF incidence and severity, notably the Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets. Several other plant-based dietary patterns, including low-fat diets and the rice diet, also show promise. Higher dietary quality, as assessed using different scores, seems to provide protective qualities. Fruit, vegetables, legumes and wholegrains appear to be beneficial, whereas red/processed meats, eggs and refined carbohydrates appear harmful. Some evidence suggests detrimental effects of dairy products and poultry, but more research is needed. There is observational and interventional evidence that a plant-based diet high in antioxidants, micronutrients, nitrate and fibre but low in saturated/trans fats may decrease the incidence and severity of HF. Potential mechanisms for this include decreased oxidative stress, homocysteine and inflammation levels, as well as higher antioxidant defence and nitric oxide bioavailability with gut microbiome modulation. Well-designed randomised, controlled nutrition intervention trials specific to HF are urgently required.

Calcium and vitamin D status in heart failure patients in Isfahan, Iran

Both calcium and vitamin D play important roles in cardiac muscle contraction and performance. In this cross-sectional study, we evaluated the status of serum calcium, PTH and 25(OH)D(3) and their correlation with left ventricular Function and NYHA Functional class in 95 heart failure patients referred to Shahid Chamran Hospital, Isfahan, Iran, by colorimetric, immunoradiometric, and Immunochemiluminescent assays, echocardiography and interview respectively. The study was performed between Oct 2007 and Feb 2008. Twenty eight women and 67 men of functional classes 1, 2, or 3 participated in the study. Mean (SD) of age of the participants was 62(11) years. Mean (SD) serum calcium and 25(OH)D(3) were 2.41(0.16) mmol/L and 56.78(51.33) nmol/L, respectively. The overall prevalence of low vitamin D status was 84.2%. There was no correlation between serum calcium and 25(OH)D(3) with LVEF. Interestingly, patients with hyperparathyroidism (serum PTH>65 ng/L) had lower LVEF (27% versus 32.5% p = 0.03). NYHA functional class was worse in patients with hyperparathyroidism (p = 0.08). Hypovitaminosis D is very prevalent in heart failure patients. Hyperparathyroidism in these patients may adversely affect cardiac function. Vitamin D3 might serve as an adjunctive treatment for heart failure patients.

Can moderate elevations of parathyroid hormone acutely increase risk for ischemic cardiac arrhythmias?

There is suggestive evidence that chronic elevations of parathyroid hormone (PTH), associated with poor vitamin D status or low calcium intake, can increase risk for insulin resistance, weight gain, hypertension, and left ventricular hypertrophy, while stimulating production of acute phase reactants. New evidence that elevated PTH is prognostic for increased vascular mortality in very elderly subjects, prompts an examination of the possible impact of PTH on risk for arrhythmias. The cardiac effects of PTH are mediated by G protein-coupled receptors that activate phospholipase C (PLC). Catecholamines, angiotensin II, and endothelin have been shown to be arrhythmogenic for ischemic myocardium in animal studies; the receptors mediating this effect are all likewise linked to activation of PLC. Thus, it is reasonable to presume that a sufficient concentration of PTH can be arrhythmogenic in the ischemic heart. The extent to which this effect can be evoked by the high-normal PTH levels prevalent in many elderly subjects, can be assessed in epidemiological studies.

Parathyroid hormone improves contractile performance of adult rat ventricular cardiomyocytes at low concentrations in a non-acute way

AIMS

In patients with congestive heart failure, plasma parathyroid hormone (PTH) levels are positively associated with cardiac function. PTH, used to mobilize stem cells from the bone marrow after myocardial infarction, causes an increased left ventricular ejection fraction. The aim of this study was to investigate whether low but plasma-relevant concentrations of PTH directly influence the contractile properties of cardiomyocytes.

METHODS AND RESULTS

Isolated adult rat ventricular cardiomyocytes were exposed to PTH(1-34) or full-length PTH at picomolar concentrations for 24 h. Cell shortening was measured at 2 Hz as a cellular correlate of inotropic responsiveness. Intracellular calcium was measured in Fura-AM-loaded cells. PTH(1-3) (20-200 pM) and full-length PTH (200 pM) increased cell shortening within 24 h. PTH had no effect on cell size, but resting and peak systolic calcium concentrations were elevated. The beneficial effect of PTH was mediated via its cAMP/protein kinase A-activating domain and attenuated by addition of a protein kinase A inhibitor. In contrast, PTH peptides representing a protein kinase C-activating domain but not a cAMP/protein kinase A-activating domain or peptides that represent none of these domains had no effect on cell shortening. The effect of PTH on cell shortening was strong at low concentrations of extracellular calcium but declined at higher calcium concentrations. PTH downregulated the expression of the calcium sensing receptor, a receptor known to antagonize the action of PTH on calcium transport. Furthermore, PTH antagonized the angiotensin II-induced loss of cell function.

CONCLUSION

Low concentrations of PTH improve cell shortening by increasing calcium load at rest. By this mechanism cardiomyocytes compensate reduced extracellular calcium levels as they occur in patients with heart failure.

Angiotensin II: a hormone involved in and contributing to pro-hypertrophic cardiac networks and target of anti-hypertrophic cross-talks

Angiotensin II (Ang II) plays a major role in the progression of myocardial hypertrophy to heart failure. Inhibiting the angiotensin converting enzyme (ACE) or blockade of the corresponding Ang II receptors is used extensively in clinical practice, but there is scope for refinement of this mode of therapy. This review summarizes the current understanding of the direct effects of Ang II on cardiomyocytes and then focus particularly on interaction of components of the renin-angiotensin system with other hormones and cytokines. New findings described in approximately 400 papers identified in the PubMed database and published during the 2.5 years are discussed in the context of previous relevant literature. The cardiac action of Ang II is influenced by the activity of different isoforms of ACE leading to different amounts of Ang II by comparison with other angiotensinogen-derived peptides. The effect of Ang II is mediated by at least two different AT receptors that are differentially expressed in cardiomyocytes from neonatal, adult and failing hearts. The intracellular effects of Ang II are influenced by nitric oxide (NO)/cGMP-dependent cross talk and are mediated by the release of autocrine factors, such as transforming growth factor (TGF)-beta1 and interleukin (IL)-6. Besides interactions with cytokines, Ang II is involved in systemic networks including aldosterone, parathyroid hormone and adrenomedullin, which have their own effects on cardiomyocytes that modify, amplify or antagonize the primary effect of Ang II. Finally, hyperinsulemia and hyperglycaemia influence Ang II-dependent processes in diabetes and its cardiac sequelae.

HYPERPARATIROSIS AND CARDIOVASCULAR SYSTEM PATHOLOGY

For many years, hyperparathyroidism, including primary, primarily associated with severe pathology of the osseous system and kidneys, was considered a rare disease. The widespread introduction into the clinical practice of the determination in the blood of calcium, and then parathyroid hormone, and osteodensitometry made it possible to recognize this disease more often and at earlier stages and to treat it more successfully. By now, the specific gravity of mild and asymptomatic forms of hyperparathyroidism has increased from 10-15% in the 1980s to 80%. Conservative management of these forms of hyperparathyroidism requires more thorough research on the prognosis of survival, duration and quality of life, and the risk of developing associated diseases in these patients.