Hemodynamic effects of inhaled terbutaline in congestive heart failure patients without lung disease: beneficial cardiotonic and vasodilator beta-agonist properties evaluated by ventricular catheterization and radionuclide angiography

Insulin signaling pathway assessment by enhancing antioxidant activity due to morin using in vitro rat skeletal muscle L6 myotubes cells

BACKGROUND

Plant-derived phytochemicals such as flavonoids have been explored to be powerful antioxidants that protect against oxidative stress-related diseases. In the present study, Morin, a flavonoid compound was studied for its antioxidant and antidiabetic properties in relation to oxidative stress in insulin resistant models conducted in rat skeletal muscle L6 cell line model.

METHODS

Evaluation of antioxidant property of morin was assayed using in vitro methods such as cell viability by MTT assay, estimation of SOD and CAT activity and NO scavenging activity. The anti-oxidative nature of morin on L6 cell line was conducted by the DCF-DA fluorescent activity. Glucose uptake in morin treated L6 myotubes are accessed by 2-NBDG assay in the presence or absence of IRTK and PI3K inhibitors. Further glycogen content estimation due to the morin treatment in L6 myotubes was performed. Antioxidant and insulin signaling pathway gene expression was examined over RT-PCR analysis.

RESULTS

Morin has a negligible cytotoxic effect at doses of 20, 40, 60, 80, and 100 µM concentration according to cell viability assay. Morin revealed that the levels of the antioxidant enzymes SOD and CAT in L6 myotubes had increased. When the cells were subjected to the nitro blue tetrazolium assay, morin lowered reactive oxygen species (ROS) formation at 60 µM concentration displaying 39% ROS generation in oxidative stress condition. Lesser NO activity and a drop in green fluorescence emission in the DCFDA assay, demonstrating its anti-oxidative nature by reducing ROS formation in vitro. Glucose uptake by the L6 myotube cells using 2-NBDG, and with IRTK and PI3K inhibitors (genistein and wortmannin) showed a significant increase in glucose uptake by the cells which shows the up regulated GLUT-4 movement from intracellular pool to the plasma membrane. Morin (60 µM) significantly enhanced the expression of antioxidant genes GPx, GST and GCS as well as insulin signalling genes IRTK, IRS-1, PI3K, GLUT-4, GSK-3β and GS in L6 myotubes treated cells.

CONCLUSION

Morin has the ability to act as an anti-oxidant by lowering ROS levels and demonstrating insulin mimetic activity by reversing insulin resistance associated with oxidative stress.

Acute decompensated heart failure is routinely treated as a cardiopulmonary syndrome

BACKGROUND

Heart failure as recognized and treated in typical practice may represent a complex condition that defies discrete categorizations. To illuminate this complexity, we examined treatment strategies for patients hospitalized and treated for decompensated heart failure. We focused on the receipt of medications appropriate for other acute conditions associated with shortness of breath including acute asthma, pneumonia, and exacerbated chronic obstructive pulmonary disease.

METHODS AND RESULTS

Using Premier Perspective(®), we studied adults hospitalized with a principal discharge diagnosis of heart failure and evidence of acute heart failure treatment from 2009-2010 at 370 US hospitals. We determined treatment with acute respiratory therapies during the initial 2 days of hospitalization and daily during hospital days 3-5. We also calculated adjusted odds of in-hospital death, admission to the intensive care unit, and late intubation (intubation after hospital day 2). Among 164,494 heart failure hospitalizations, 53% received acute respiratory therapies during the first 2 hospital days: 37% received short-acting inhaled bronchodilators, 33% received antibiotics, and 10% received high-dose corticosteroids. Of these 87,319 hospitalizations, over 60% continued receiving respiratory therapies after hospital day 2. Respiratory treatment was more frequent among the 60,690 hospitalizations with chronic lung disease. Treatment with acute respiratory therapy during the first 2 hospital days was associated with higher adjusted odds of all adverse outcomes.

CONCLUSIONS

Acute respiratory therapy is administered to more than half of patients hospitalized with and treated for decompensated heart failure. Heart failure is therefore regularly treated as a broader cardiopulmonary syndrome rather than as a singular cardiac condition.

Are beta2-agonists responsible for increased mortality in heart failure?

AIMS

Previous large-scale, retrospective studies have shown increased mortality in heart failure (HF) patients using β2-agonists (B2As). We further examined the relationship between B2A use and mortality in a well-characterized population by adjusting for natriuretic peptide levels as a measure of HF severity.

METHODS AND RESULTS

This was a retrospective cohort study of patients attending an HF Disease Management Programme with mean follow-up of 2.9 ± 2.4 years. Chart review confirmed B2A use, dose and duration of use, and documented pulmonary function evaluation. The primary endpoint was the effect of B2A use compared with no B2A use on mortality using unadjusted and adjusted Kaplan-Meier survival curves. Data were available for 1294 patients (age 70.6 ± 11.5 years) of whom 64% were male and 22.2% were taking B2As. β2-Agonist users were older, more likely to be male, to have smoked, to have chronic obstructive pulmonary disease (COPD) and asthma, and less likely to take beta-blockers. Multivariable associates of mortality included: B-type natriuretic peptide (BNP), coronary artery disease, age, and beta-blocker use. Unadjusted mortality rates for B2A users were found to be significantly higher than non-B2A users [hazard ratio (HR) 1.304, 95% confidence interval (CI) 1.030-1.652, P= 0.028]. However, when adjusted for age, sex, medication, co-morbidity, smoking, COPD, and BNP differences, overall mortality rates were similar [HR 1.043, 95% CI (0.771-1.412), P= 0.783].

CONCLUSION

Unlike previous reports, this retrospective evaluation of B2A therapy in HF patients shows no relationship with long-term mortality when adjusted for population differences including BNP.  Large, prospective studies are required to define the risk/benefit ratio of B2As in patients with heart failure.

Mode of action of beta-adrenoceptor blocking agents in hypertension. A comparison between metoprolol and pindolol with special reference to peripheral vascular effects

beta-Adrenoceptor blocking drugs are generally recognized as being effective in the treatment of hypertension. The mechanisms whereby these drugs reduce blood pressure are, however, not fully understood. In a double-blind, randomized study either metoprolol, 100--300 mg/day, or pindolol, 5--15 mg/day, was given for 6 months and the effects on blood pressure, heart rate and vascular resistance in the calf and forearm were investigated. Measurements were made at rest, during and after physical exercise, and during postischaemic hyperaemia. Both drugs reduced blood pressure to the same extent both at rest and during and after exercise. Metoprolol reduced heart rate to a greater extent than pindolol at rest and after exercise, whereas no difference was seen during physical exercise. Pindolol reduced the vascular resistance in the calf at rest by 14% (p less than 0.05), whereas metoprolol tended to increase vascular resistance, the difference in effect being highly significant (p less than 0.005). During and after leg exercise, there was no difference in forearm vascular resistance between the two drugs. It may be concluded that pindolol reduced resting blood pressure partly through peripheral vasodilatation. This was probably an effect of beta 2-adrenoceptor stimulation linked to the pronounced intrinsic sympathomimetic activity (ISA) of pindolol. Metoprolol on the other hand, acted mainly through cardiac mechanisms, as suggested by its pronounced reduction of heart rate.

Should acute treatment with inhaled beta agonists be withheld from patients with dyspnea who may have heart failure?

In patients with dyspnea, prehospital and emergency providers make therapeutic decisions before a diagnosis is established. Inhaled beta-2 agonists are frontline treatment for patients with dyspnea due to asthma or chronic obstructive pulmonary disease (COPD) exacerbations. However, these agents have been associated with increased adverse events when administered chronically to heart failure patients. Our goal was to determine the safety and efficacy of acute administration of inhaled beta-2 agonists to patients with heart failure. MEDLINE and EMBASE searches were performed using the terms "beta agonists," "albuterol," "congestive heart failure," and "pulmonary edema." Bibliographies of relevant articles were searched. Only studies addressing acute effects of beta-2 agonists were included for analysis. Twenty-four studies comprising 434 patients were identified that addressed the acute delivery of beta-2 agonists in subjects with heart failure--five studies with inhaled administration and 19 with systemic administration. No study directly evaluated the effects of inhaled beta-2 agonists to patients with acutely decompensated heart failure. Treatment of heart failure patients with beta-2 agonists resulted in transient improvements in pulmonary function and cardiovascular hemodynamics. Only one investigation reported an association between beta-2 agonist use and an increase in malignant dysrhythmias. Investigations in animal models of heart failure and acute lung injury demonstrated resolution of pulmonary edema with beta agonist administration. There is insufficient evidence to suggest that acute treatment with inhaled beta-2 agonists should be avoided in patients with dyspnea who may have heart failure. Based on small studies and indirect evidence, administration of beta-2 agonists to patients with heart failure seems to improve pulmonary function, cardiovascular hemodynamics, and resorption of pulmonary edema. Although an increase in adverse effects with the use of beta-2 agonists cannot be ruled out based on these data, there was no evidence of an increase in clinically significant dysrhythmias, especially when administered by inhalation. Based on these findings, further study should focus on the clinical outcomes of patients with acutely decompensated heart failure who are treated with inhaled beta-2 agonist therapy.

Terbutaline for chronotropic support in heart transplantation

OBJECTIVE

To report the use of oral terbutaline for chronotropic support in a patient who had undergone heart transplantation.

CASE SUMMARY

A 54-year-old white man received a heart transplant secondary to ischemic dilated cardiomyopathy. His clinical course was uncomplicated until postoperative day 10, when he became hemodynamically compromised despite inotropic therapy (BP 88/53 mm Hg, mean HR 80 beats/min) secondary to stage IIIa rejection. Although a continuous intravenous infusion of dobutamine was maintained, therapy with oral terbutaline 2.5 mg every 6 hours was initiated. Because the patient remained bradycardic on postoperative day 11 (HR 64 beats/min; mean 75), terbutaline was titrated to a dosage of 5 mg every 8 hours. Subsequently, an improvement in the hemodynamic profile (BP 140/78 mm Hg, mean HR 91 beats/min) was noted. Treatment with terbutaline was continued for 13 days and was well tolerated.

DISCUSSION

As of February 11, 2004, this is the first case, to our knowledge, to describe the use of oral terbutaline therapy for chronotropic support in the setting of acute rejection after heart transplantation. Terbutaline is a beta2-adrenergic agonist that may mediate its effects via direct beta2-receptor stimulation, baroreceptor-mediated increases in sympathetic tone, or via presynaptic beta2-stimulation. Although isoproterenol has been the mainstay of therapy for chronotropic support in this setting, its availability has been an issue in recent years. Terbutaline, therefore, may represent a useful alternative for chronotropic support in the setting of heart transplantation.

CONCLUSIONS

Terbutaline therapy did not appear to be associated with any significant adverse effects and warrants further application and study in this setting.

Congestive heart failure and pulmonary edema for the emergency physician

Congestive heart failure (CHF) and pulmonary edema are major health problems in the United States as well as across the rest of the developing world. The prevalence of CHF and pulmonary edema in the general population results in a significant number of these patients presenting to Emergency Departments (EDs). Mortality from these disorders is substantial, with a 5-year mortality rate for patients requiring hospitalization of approximately 50%. Understanding of the clinical syndromes of CHF and pulmonary edema requires review of the basic determinants of cardiovascular performance. Preload, afterload, contractility, and heart rate may all be modified by pharmacological or mechanical techniques. Diuretics, vasodilators, cardiac glycosides, and other inotropes all may play a role in the ED management of CHF. In rare instances, mechanical devices for support of the heart and circulation may be indicated.

General overview and update of positive inotropic therapy

Advances in our understanding of the pathophysiology of cardiac-ventricular failure and the pharmacophysiology of adrenergic receptors have greatly improved the short-term therapy of the low-output, hypotensive-hypoperfused, cardiac failure states. Agents are now specifically selected for these conditions on the basis of their predominant effects on the heart (positive inotropy) and the peripheral vasculature (vasodilatation or vasoconstriction). With the addition of dobutamine therapy, the pharmacophysiologic spectrum now includes norepinephrine (predominant vasopressor), dopamine (combined vasopressor-positive inotrope), dobutamine (predominant positive inotrope), and isoproterenol (combined positive inotrope-vasodilator). Digitalis was introduced to the medical profession 200 years ago. In terms of chronically administered positive inotropic therapy, to date, this "old-timer" has not been replaced. The yet experimental phosphodiesterase inhibitors, enoximone and milrinone, appear promising as long-term nonparenteral inotropes; however, the precise role, clinical effectiveness, and safety profile of these agents remain to be determined.

Cardiovascular effects of intramuscular or inhaled terbutaline in asthmatics

8 stable asthmatics were at random given placebo, 0.125 mg, 0.25 mg, 0.5 mg and 1 mg terbutaline intramuscularly or 2.5 mg as inhalation. Systolic time intervals, echocardiographic parameters and peak expiratory flow (PEF) were measured. Maximal circulatory and respiratory response was obtained after 0.5 mg and 0.25 mg, respectively. The circulatory effect of 2.5 mg inhaled terbutaline equalled 0.125 mg given intramuscularly, while this dosage elicited maximal bronchodilator effect. Thus, nebulized terbutaline has only a minimal circulatory effect, and even the intramuscular dosages were without dramatic circulatory side effects.

Myocardial metabolic effects of intravenous terbutaline in patients with severe heart failure due to coronary artery disease

Intravenous terbutaline, 0.3 mg/kg/min for 30 minutes followed by 0.15 mg/min for 60 minutes, was studied in nine patients with severe heart failure due to documented coronary artery disease. Hemodynamic and myocardial metabolic effects were measured during terbutaline infusion. Cardiac index and stroke index increased, whereas mean pulmonary artery wedge pressure and pulmonary vascular resistance decreased significantly. No significant alterations in aortic oxygen content, coronary sinus oxygen content, myocardial oxygen extraction, and myocardial lactate extraction were observed during terbutaline infusion. No patient developed angina or electrocardiographic changes suggestive of ischemia. These results indicate that intravenous terbutaline infusion, at the dosage employed, produces beneficial hemodynamic effects without a deterioration of myocardial metabolism in patients with heart failure due to coronary artery disease.

Hemodynamic, hormonal and electrolyte responses to prenalterol infusion in heart failure

The hemodynamic, hormonal and electrolyte effects of prenalterol, a synthetic selective beta 1 agonist, were studied in six patients with New York Heart Association functional class II and III heart failure. Prenalterol was infused incrementally at 60, 120 and 240 nmol/min, each rate for 24 hours, producing steady-state plasma prenalterol levels of 52 +/- 3, 121 +/- 6 and 194 +/- 9 nmol/1, respectively (mean +/- SEM). Hemodynamic and hormonal measurements were performed before, during and after prenalterol administration under conditions of constant body posture and a regulated intake of dietary sodium and potassium. Prenalterol induced a statistically significant increase in cardiac index (from 2.6 +/- 0.2 to 3.1 +/- 0.3 1/min/m2), with parallel increases in stroke index (from 28 +/- 2 to 34 +/- 2 ml/beat/m2). Forearm blood flow measurements increased (from 2.9 +/- 0.5 to 4.1 +/- 0.6 ml/min/100 g), while calculated systemic vascular resistance fell, as did pulmonary capillary wedge pressure (from 13.7 +/- 1.6 to 10.5 +/- 1.7 mm Hg). The drug did not alter heart rate, arterial pressure, right heart pressures or the frequency of ventricular premature beats. Prenalterol increased plasma renin activity (from 2.9 +/- 0.8 to 6.6 +/- 1.8 nmol/1/hour), angiotensin II (from 59 +/- 12 to 89 +/- 22 pmol/1), urinary aldosterone excretion (from 41 +/- 10 to 78 +/- 34 nmol/day) and plasma insulin (from 10.6 +/- 2.2 to 19.8 +/- 3.9 mU/1). Circulating catecholamines, cortisol, glucose, glucagon or pancreatic polypeptide did not change. Dose-response studies in five patients showed dose-dependent increments in hemodynamic variables, while hormonal changes plateaued at the second dose level. We conclude that prenalterol infusion augments myocardial contractility, reduces systemic vascular resistance, and stimulates insulin release and the renin-angiotensin-aldosterone system.

Haemodynamic effects of metoprolol and pindolol: a comparison in hypertensive patients

1 In a double-blind study, 36 patients with essential hypertension were randomly allocated to treatment with either metoprolol, 100--300 mg/day, or pindolol, 5--15 mg/day for 6 months. Haemodynamic investigations were made on three separate occasions. Blood flow in the calves and in the forearm was determined by venous occlusion plethysmography after 6 weeks of placebo, after 6 weeks and again after 6 months of active therapy. 2 Both drugs reduced blood pressure significantly, by 17.1/11.8 mm Hg with metoprolol and 21.9/10.9 mm Hg with pindolol after 6 weeks (P less than 0.005). No further changes were seen after 6 months. 3 Heart rate after 6 weeks was significantly reduced by metoprolol (10.7 +/- 2.4 beats/min, P less than 0.001) but not by pindolol (4.4 +/- 2.3 beats/min, NS). After 6 months a significant reduction was seen also in the pindolol group (5.2 +/- 2.1 beats/min, P less than 0.05). 4 The vascular resistance in the calves at rest was reduced by pindolol (P less than 0.05), whereas resistance tended to increase with metoprolol. 5 Resting vascular resistance in the forearm after 6 months was significantly reduced in the metoprolol group (P less than 0.001) as well as in the pindolol group (P less than 0.02). The increase in forearm vascular resistance seen during leg exercise was not influenced by either drug. 6 Vascular resistance at maximal vasodilatation was unchanged in the calves, but a significant reduction (-17.4 +/- 5.7%, P less than 0.01) in the forearm vascular bed was seen after 6 months of pindolol. No change was observed with metoprolol. 7 It is concluded that pindolol reduces elevated blood pressure partly through peripheral vascular mechanism. Metoprolol, on the other hand, probably acts mainly via central cardiac mechanisms.