Effect of atenolol and celiprolol on acetylcholine-induced coronary vasomotion in coronary artery disease

Nebivolol: the somewhat-different beta-adrenergic receptor blocker

Although its clinical use in Europe dates almost 10 years, nebivolol is a beta-blocker that has been only recently introduced in the U.S. market. Like carvedilol, nebivolol belongs to the third generation of beta-blockers, which possess direct vasodilator properties in addition to their adrenergic blocking characteristics. Nebivolol has the highest beta(1)-receptor affinity among beta-blockers and, most interestingly, it substantially improves endothelial dysfunction via its strong stimulatory effects on the activity of the endothelial nitric oxide synthase and via its antioxidative properties. Because impaired endothelial activity is attributed a major causal role in the pathophysiology of hypertension, coronary artery disease, and congestive heart failure, the endothelium-agonistic properties of nebivolol suggest that this drug might provide additional benefit beyond beta-receptor blockade. Although lesser beta-blocker-related side effects have been reported in patients with chronic obstructive pulmonary disease or impotence taking nebivolol, side effects and contraindications overlap those of other beta-blockers. Clinically, this compound has been proven to have antihypertensive and anti-ischemic effects as well as beneficial effects on hemodynamics and prognosis in patients with chronic congestive heart failure. Further studies are now necessary to compare the benefit of nebivolol with that of other drugs in the same class and, most importantly, its prognostic impact in patients with hypertension.

Cardiovascular pharmacotherapy update for the intensive care unit

Pharmacologic agents including vasodilators, inotropes, and vasopressors are frequently used in the critical care setting for management of the unstable cardiac patient. These medications are used to elicit varying effects on vascular resistance, myocardial contractility, and heart rate to help achieve desired hemodynamic and clinical endpoints. Therefore, it is important for the critical care nurse to have a practical understanding and working knowledge of cardiovascular pharmacotherapy in the intensive care unit setting. This article reviews the pharmacology and clinical utility of commonly used intravenous "vasoactive" medications encountered in the intensive care unit. We also highlight innovations in pharmacotherapy for this patient population, and provide practical considerations for the most appropriate and safe use of these medications.

β1 antagonist and β2 agonist, celiprolol, restores the impaired endothelial dependent and independent responses and decreased TNFα in rat with type II diabetes

The effect of beta antagonists in the diabetic vascular lesion is controversial. We investigated the effect of celiprolol hydrochloride, a beta1 antagonist and mild beta2 agonist, on the lesions and function in type II male Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rats. OLETF rats were fed regular chow with or without atenolol (25 mg/kg/day) or celiprolol (100 mg/kg/day) treatment (group DM, no treatment; group DM-a, atenolol treatment; group DM-c, celiprolol treatment), and treatment was continued for 31 days. Separately, normoglycemic control rats, LETO, were prepared as group C. On day 3, endothelial cells of the right internal carotid artery were removed by balloon injury, and the rats were evaluated 4 weeks after balloon injury. The plasma glucose and lipid levels were unchanged throughout the treatment period. Intimal thickening was observed in the right carotid artery in the DM and DM-a groups; however, little thickening was observed in those of DM-c rats. Acetylcholine-induced NO-dependent relaxation in arteries was improved in DM-c rats compared with DM and DM-a rats (maximum relaxation DM 30.8+/-4.5, DM-a 37.4+/-3.9, DM-c 48.8+/-4.6%, *P<0.05 vs. DM for DM-c rats). Tone-related basal NO release and acetylcholine-induced NO-dependent relaxation in the arteries and plasma NO(x) (sum of NO(2)(-) and NO(3)(-)) were greater in DM-c and C groups than in DM and DM-a groups. The serum TNFalpha levels did not increase in DM-c rats compared with those of the DM or DM-a groups, and were comparable with those of group C.

CONCLUSION

In conclusion, Celiprolol improves endothelial function in the arteries of OLETF rats, and further restore it 4 weeks after endothelial denudation in the arteries of OLETF rats. NO and O(2)(-) may have a role in the important underlying mechanisms by reducing the TNFalpha levels.

Cellular mechanisms for the treatment of chronic heart failure: the nitric oxide- and adenosine-dependent pathways

Accumulated evidence suggests that several drugs proven to improve survival in patients with chronic heart failure (CHF) enhance endogenous nitric oxide (NO)- and/or adenosine-dependent pathways. Indeed, we and others have demonstrated that: i) antagonists of either renin-angiotensin-aldosterone or beta-adrenergic systems enhance NO-dependent pathways; ii) although carvedilol and amlodipine belong to different drug classes, both of them can increase cardiac adenosine levels; iii) increased adenosine levels by dipyridamole are associated with the improvement of CHF. Interestingly, both NO and adenosine have multifactorial beneficial actions in cardiovascular systems. First of all, both of them induce vasodilation and decrease myocardial hypercontractility, which may contribute to a reduction in the severity of myocardial ischaemia. Both adenosine and NO are also involved in cardioprotection attributable to acute and late phases of ischaemic preconditioning, respectively. Secondly, they can modulate the neurohormonal systems that contribute to the progression of CHF. Thus, we propose that enhancement of endogenous NO and/or adenosine as potential therapeutic targets in a new strategy for the treatment for CHF.

Design of therapy for advanced heart failure

Advanced heart failure has been defined as persistent symptoms (NYHA class III-IV) that limit daily life despite routine therapy with agents of known benefit. Although these symptoms can occur both with low and preserved ejection fraction, the majority of reported experience is with low ejection fraction, usually <25%. For this population with expected one year mortality of 30-50%, over twice the mortality of the landmark trials of medical therapy, there is little trial data to guide management, which is based largely on collected experience. Once the disease has progressed to this stage, therapy focuses upon the twin goals of symptom relief and prolongation of survival and is guided according to the hemodynamic profiles defined by clinical assessment. As symptoms at this stage relate largely to the congestion, therapy is targeted to reduction of elevated pulmonary venous and/or systemic venous pressures to near normal levels. The most common obstacle to relief of congestion is the increasingly recognized cardio-renal syndrome, for which both understanding and therapy are currently limited. Design of the outpatient regimen for advanced heart failure must be tailored to the individual patient. Many patients with advanced heart failure cannot tolerate "target" doses of neurohormonal antagonists, and spironolactone should be used only when clinical and renal function are sufficiently stable and frequently monitored in order to avoid life-threatening hyperkalemia. The clinical benefit of bi-ventricular pacing is substantial for the small proportion of patients likely to benefit. The vast majority of patients will never be eligible for cardiac transplantation or ventricular assist devices. To derive maximal benefit from all available therapies, heart failure disease management with collaboration of physicians and specialized nurses offers the greatest benefit to the greatest number of patients with advanced heart failure.

Nesiritide during extracorporeal membrane oxygenation

Nesiritide is a recombinant formulation of B-type natriuretic peptide (BNP). Preliminary experience in the adult population has shown nesiritide to be an effective agent in the treatment of decompensated congestive heart failure (CHF) in adults. Given its physiological effects, it may be an effective agent in other clinical scenarios. We report the use of nesiritide in two infants during extracorporeal membrane oxygenation (ECMO). In one patient, nesiritide in doses up to 0.09 microg.kg(-1).min(-1) were used to control mean arterial pressure while in the other patient, doses of 0.01-0.03 microg.kg(-1).min(-1) were used to augment urine output. The potential applications of nesiritide and dosing regimens for this agent in the ECMO population are discussed.

Preliminary experience with nesiritide in the pediatric population

Nesiritide is a recombinant formulation of brain-type natriuretic factor. Preliminary experience in the adult population suggests that nesiritide may be an effective agent in the treatment of decompensated congestive heart failure. Given its physiologic effects, it may be an effective agent in the pediatric population; however, to date, there are no reports regarding its use in infants and children. The authors retrospectively review their experience with nesiritide in 5 pediatric patients. The cohort of 5 patients included a diverse population with 2 patients who were status postcardiothoracic surgery, 2 with adult respiratory distress syndrome, and 1 in the recovery phase from septic shock. Although no direct measurement of cardiac output was feasible as none of the patients had a pulmonary artery catheter, other indicators of increased cardiac output were noted. These included improved peripheral perfusion with warming of the extremities and improvement of peripheral pulses in all of the patients, increased venous saturation in 2 of the patients, and maintenance of or increased urine output despite weaning or discontinuation of diuretics. In 3 of the patients, nesiritide was started as the primary agent to provide a decrease in systemic vascular resistance and augment cardiac output, while in the other 2 patients, nesiritide was used when other vasoactive agents failed to provide the desired effect or resulted in adverse effects.

Impact of physical training and detraining on endothelium-dependent vasodilation in patients with recent acute myocardial infarction

BACKGROUND

There is evidence that aerobic exercise improves endothelial function in healthy subjects as well as in patients with chronic heart failure. However, it is unknown whether this effect occurs in patients with recent myocardial infarction (AMI).

METHODS

Fifty-two patients with a recent first uncomplicated AMI underwent endothelial function evaluation before and after 3 months of moderate aerobic exercise training. We measured brachial artery vasomotor reactivity using flow-mediated dilation (FMD), a cold pressor (CP) test, and sublingual nitroglycerin. Patients were randomized into 2 groups: 28 patients (G1) underwent training, while 24 patients (G2) served as controls. Brachial artery vasomotor reactivity was reassessed after 1 month of detraining (DT).

RESULTS

At baseline the FMD was 1.66% +/- 4.11% in G1 and 2.04% +/- 3.4% in G2 (P = NS) and vasoconstriction was evident after a CP test. The diameter reduction was -4.1% +/- 3.89% in G1 and -4.39% +/- 5.67% in G2 (P = NS). At follow-up the FMD had increased to 9.39% +/- 4.87% in G1 (P <.01) and to 4.4% +/- 3.9% in G2 (P <.01 vs G1). Vasoconstriction during a CP test was observed only in G2. Endothelium-independent vasodilation was unchanged in both groups. Effort tolerance increased by 32% in G1 patients (P <.01 versus G2) and was correlated with FMD change (R = 0.51, P <.01). After detraining the FMD was significantly reduced in G1 (P <.01) and a further vasoconstriction was evident after CP testing.

CONCLUSIONS

Exercise training improves endothelium-dependent vasodilation in post-AMI patients. This improvement is associated with a significant increase in exercise tolerance. These benefits disappeared after detraining.

Nesiritide: a novel approach for acute heart failure

OBJECTIVE

To review preclinical and clinical information related to nesiritide, a recombinant form of B-type natriuretic peptide approved for treatment of acutely decompensated heart failure.

DATA SOURCES

Primary and review articles were identified by MEDLINE search (1966-May 2002) using the key words natriuretic peptide and heart failure, and through secondary sources. Natrecor's document submitted for the Food and Drug Administration (FDA) New Drug Application were obtained from the FDA Web site.

STUDY SELECTION/DATA EXTRACTION

Peer-reviewed articles and abstracts of randomized clinical trials in humans were included in this review.

DATA SYNTHESIS

Nesiritide has beneficial actions for treatment of heart failure, including arterial and venous dilatation, enhanced sodium and urinary excretion, and suppression of the renin-angiotensin-aldosterone and sympathetic nervous systems. It has been shown to improve hemodynamic parameters, primarily pulmonary capillary wedge pressure, as well as clinical symptoms in patients with acutely decompensated heart failure. Nesiritide produced more rapid hemodynamic improvement and caused significantly fewer adverse effects than intravenous nitroglycerin. The incidence of hypotension, the most common adverse effect, was comparable between nesiritide and nitroglycerin. Additionally, nesiritide is associated with a lower incidence of arrhythmias than dobutamine and has a neutral effect on mortality.

CONCLUSIONS

Nesiritide offers an alternative for management of acutely decompensated heart failure. It is considered an option for patients who do not respond to other vasodilators, inotropes, or diuretics and for those at high risk of arrhythmias. Further pharmacoeconomic investigations for nesiritide are warranted.

Cardiovascular effects of beta-blockers with and without intrinsic sympathomimetic activity. A comparison between celiprolol and metoprolol

BACKGROUND

Celiprolol, a newer beta-blocking agent, has been reported to have vasodilatory capacity which may be due to partial beta-2-receptor agonistic activity or to alpha-receptor antagonistic or central sympathoinhibitory effects.

METHODS

To more critically assess the physiologic effects of celiprolol, we measured sympathetic nerve activity to muscle (MSNA), forearm blood flow (FBF), blood pressure (BP), central venous pressure, and heart rate (HR) in 10 normal volunteers at rest, during unloading of cardiopulmonary baroreceptors with lower body negative pressure (LBNP), and during a cold pressor test (CPT). Responses were compared with those seen with metoprolol and with placebo, i.e. each subject was studied three times.

RESULTS

Celiprolol did not alter resting levels of hemodynamics, FBF, and MSNA nor did it alter responses to LBNP or the CPT. In contrast, metoprolol produced significant decreases of FBF and HR, and increases of forearm vascular resistance and BP, but had also no effect on responses to the applied stress tests.

CONCLUSIONS

The lack of peripheral vasoconstriction seen after acute administration of celiprolol is most likely due to its partial beta-2-receptor agonistic effect and does not seem to be due to a central or reflex action or to an alpha-blocking effect. Both beta-blockers do not impair fundamental neural mechanisms involved in circulatory homeostasis.

Better preserved pulmonary endothelium-dependent vasodilation with off-pump coronary surgery

OBJECTIVE

To investigate if endothelium-dependent vasodilation in the pulmonary circulation was better maintained after off-pump coronary artery bypass grafting (CABG). An impaired pulmonary vascular response to acetylcholine has been observed after cardiopulmonary bypass (CPB) in children, adults and experimentally.

DESIGN

Fourteen patients operated off-pump were compared with 21 patients undergoing conventional CABG with CPB. The indexed pulmonary vascular resistance was measured before and during an infusion of acetylcholine, aiming at a concentration of 10(-6) mol/l in the pulmonary artery. Twelve patients operated on-pump received saline instead of acetylcholine.

RESULTS

Before surgery pulmonary vascular resistance decreased during infusion of acetylcholine by 28% and 25% in the off-pump and on-pump groups. After surgery the decrease was 16% and 6%, respectively (p = 0.028 and p < 0.001, compared to preoperative response). The response did not differ between the two groups before, but did so after surgery (p = 0.01). Saline had no effect.

CONCLUSION

The better maintained endothelium-dependent vasodilation in the off-pump group indicated less endothelial dysfunction.