The effect of different β-blockers on vascular graft nitric oxide levels: comparison of nebivolol versus metoprolol

Therapeutic Options for Migraines in the Microsurgical Patient: A Scoping Review

BACKGROUND

There exists an increasing array of treatments proposed to prevent, alleviate, and abort symptoms of a migraine; however, for patients who undergo reconstructive microsurgery, caution must be taken to preserve vascular integrity. This study is the first-to-date scoping review of vascular and bleeding risk of current migraine therapies, with the purpose of identifying potential therapeutic agents for postoperative migraine management appropriate for microsurgical patients.

METHODS

Currently available migraine therapeutics were compiled from the UpToDate software system and the American Academy of Family Physicians. A PubMed literature review was performed for each therapeutic's effect on bleeding or vascular involvement. Data were compiled into tables of abortive, symptom-controlling and prophylactic, and nonpharmacologic treatments. Expert microsurgeons reviewed the data to provide recommendations for optimized patient care.

RESULTS

Triptans and other ergot derivatives demonstrated strong evidence of vasoconstriction and were greatly advised against for immediate postmicrosurgical use. Novel pharmaceutical therapies such as lasmiditan and calcitonin gene-related peptide antagonists have no literature indicating potential for vasoconstriction or hematoma and remain an investigational option for abortive medical treatment. For symptom control, acetaminophen appears the safest option, with clinical judgment and further research needed for use of nonsteroidal antiinflammatory drugs. Alternative treatment techniques may include migraine prophylaxis with botulinum toxin injection or nutraceutical treatment by means of magnesium supplementation or coenzyme Q10 administration, minimizing the need for additional medication in the postoperative setting.

CONCLUSIONS

Patients undergoing reconstructive microsurgery have a unique medical profile limiting the therapeutic options available to treat migraines. This review provides preliminary evidence to be considered as a guide for prescribing therapeutics for migraine in the postoperative setting.

Effects of nebivolol versus other antihypertensive drugs on the endothelial dysfunction in patients with essential hypertension

We aim to determine whether nebivolol has a better effect on endothelial dysfunction compared with other β-blockers or other classes of antihypertensive drugs. Searches of the PubMed, Embase etc. were performed to analyze all the randomized controlled trials using nebivolol to treat essential hypertension. The primary end points included a measurement of peripheral endothelial function by brachial flow mediated vasodilatation (FMD) or forearm blood flow (FBF). A random-effect model was used to perform the meta-analysis when the studies showed significant heterogeneity, otherwise a descriptive analysis was conducted. Ten studies (689 patients) were included in qualitative analysis, four of which were included in quantitative synthesis. Meta-analysis showed that the changed FMD value before and after treatment with nebivolol was not statistically different from those treated with other β-blockers [mean difference = 1.12, 95% confidence interval (CI): −0.56, 2.81, P=0.19]. Descriptive analysis indicated that nebivolol did not have a better endothelium-protective effect than other classes of antihypertensive drugs including olmesartan and perindopril. Nebivolol is not a unique endothelial function-protective agent distinguished from other β-blockers or other classes of antihypertensive drugs. Reversal of endothelial dysfunction is a key point in the prevention and therapy of essential hypertension.

Vasa vasorum of the failed aorto-coronary venous grafts

PURPOSE

This study was designed to investigate the distribution of vasa vasorum in walls of failed aorto-coronary venous grafts.

METHODS

Fifty-one diseased venous grafts harvested from 39 patients underwent qualitative histological evaluation. The morphology of the grade of the pathological changes and the extent of the vascularisation were examined, and related to the length of the interval between the primary surgery and the explantation. The obtained results were placed into five groups, substantially differing one from the other in morphology and vascularisation.

RESULTS

The intervals between grafts implantation and explantation ranged from 1 day to 35 years. The onset of arterialization of the graft media was observed on average at 1 month after bypass implantation. During this same time period massive intimal hyperplasia and atherosclerosis occurred. Vasa vasorum proliferation from the adventitia to the outer layers of the media was first apparent between 7 and 24 months after implantation. Proliferation of the vasa vasorum throughout the entire atherosclerotic media and hyperplastic intima continued for a much longer time interval.

CONCLUSION

No correlation between neoangiogenesis and age, sex or type of bypassed coronary branch was proven. Regarding the given findings, the authors believe that changes in hemodynamic conditions and endothelial trauma are primarily responsible for the development of graft disease and that vasa vasorum proliferation is only a secondary reaction to the structural changes of the graft wall. To what extent the frequently present pre-existing intimal hyperplasia of venous bypass grafts play in the development of graft disease remains questionable.

Comparative Investigation of Protective Effects of Metyrosine and Metoprolol Against Ketamine Cardiotoxicity in Rats

This study investigated the effect of metyrosine against ketamine-induced cardiotoxicity in rats and compared the results with the effect of metoprolol. In this study, rats were divided into groups A, B and C. In group A, we investigated the effects of a single dose of metyrosine (150 mg/kg) and metoprolol (20 mg/kg) on single dose ketamine (60 mg/kg)-induced cardiotoxicity. In group B, we investigated the effect of metyrosine and metoprolol, which were given together with ketamine for 30 days. In group C, we investigated the effect of metyrosine and metoprolol given 15 days before ketamine and 30 days together with ketamine on ketamine cardiotoxicity. By the end of this process, we evaluated the effects of the levels of oxidant-antioxidant parameters such as MDA, MPO, 8-OHGua, tGSH, and SOD in addition to CK-MB and TP I on cardiotoxicity in rat heart tissue. The experimental results show that metyrosine prevented ketamine cardiotoxicity in groups A, B and C and metoprolol prevented it in only group C.

Nitric Oxide Contributes to Vasomotor Tone in Hypertensive African Americans Treated With Nebivolol and Metoprolol

Endothelial dysfunction is more prevalent in African Americans (AAs) compared with whites. The authors hypothesized that nebivolol, a selective β1 -antagonist that stimulates nitric oxide (NO), will improve endothelial function in AAs with hypertension when compared with metoprolol. In a double-blind, randomized, crossover study, 19 AA hypertensive patients were randomized to a 12-week treatment period with either nebivolol 10 mg or metoprolol succinate 100 mg daily. Forearm blood flow (FBF) was measured using plethysmography at rest and after intra-arterial infusion of acetylcholine and sodium nitroprusside to estimate endothelium-dependent and independent vasodilation, respectively. Physiologic vasodilation was assessed during hand-grip exercise. Measurements were repeated after NO blockade with L-N(G) -monomethylarginine (L-NMMA) and after inhibition of endothelium-derived hyperpolarizing factor (EDHF) with tetraethylammonium chloride (TEA). NO blockade with L-NMMA produced a trend toward greater vasoconstriction during nebivolol compared with metoprolol treatment (21% vs 12% reduction in FBF, P=.06, respectively). This difference was more significant after combined administration of L-NMMA and TEA (P<.001). Similarly, there was a contribution of NO to exercise-induced vasodilation during nebivolol but not during metoprolol treatment. There were significantly greater contributions of NO and EDHF to resting vasodilator tone and of NO to exercise-induced vasodilation with nebivolol compared with metoprolol in AAs with hypertension.

Clinical Significance of Endothelial Dysfunction in Essential Hypertension

The endothelium is recognized as a major determinant of vascular physiology and pathophysiology. Over the last few decades, a plethora of studies have implicated endothelial dysfunction in the progression of atherosclerosis and the subclinical target organ damage observed in essential hypertension. However, the clinical significance of diagnosing endothelial dysfunction in patients with essential hypertension remains under investigation. Although a number of vascular and non-vascular markers of endothelial dysfunction have been proposed, there is an ongoing quest for a marker in the clinical setting that is optimal, inexpensive, and reproducible. In addition, endothelial dysfunction emerges as a promising therapeutic target of agents that are readily available in clinical practice. In this context, a better understanding of its role in essential hypertension becomes of great importance. Here, we aim to investigate the clinical significance of endothelial dysfunction in essential hypertension by accumulating novel data on (a) early diagnosis using robust markers with prognostic value in cardiovascular risk prediction, (b) the association of endothelial dysfunction with subclinical vascular organ damage, and (c) potential therapeutic targets.

Labetalol, nebivolol, and propranolol relax human radial artery used as coronary bypass graft

OBJECTIVE

Beta-blockers are a heterogeneous class of agents that are used in the treatment of many cardiovascular diseases, especially hypertension and atherosclerosis, and that are commonly prescribed after cardiac surgery. In the present study, the aim is to investigate the vasorelaxant effects of some common beta-adrenoceptor blockers on the human radial artery in vitro, as well as their relaxation mechanisms.

METHODS

Radial artery rings sourced from human patients were mounted in an organ bath and tested for changes in isometric tension in relaxation response to labetalol, nebivolol, and propranolol in the presence and absence of NG-nitro-L-arginine methyl ester (3 × 10(-5) mol/L) and tetraethyl ammonium (3 × 10(-4) mol/L).

RESULTS

The labetalol (10(-8) to 10(-4) mol/L), nebivolol (10(-8) to 10(-4) mol/L), and propranolol (10(-8) to 10(-4) mol/L) induced concentration-dependent relaxations on the radial artery rings, which had been precontracted with phenylephrine (10(-6) mol/L). The relaxation response induced by labetalol in the isolated radial artery rings was significantly higher when compared with the nebivolol and propranolol samples (P < .05). NG-nitro-L-arginine methyl ester significantly reduced the relaxation of nebivolol (P < .05), and tetraethyl ammonium significantly reduced the relaxation of labetalol, nebivolol, and propranolol (P < .05).

CONCLUSIONS

We speculated that the relaxant effect of labetalol, nebivolol, and propranolol was due partly to the Ca(2+)-activated K(+) channels. In addition, the relaxation induced by nebivolol was largely related with nitric oxide release. Nebivolol, and partly propranolol, may provide significant therapeutic benefit, but labetalol can be a good alternative for coronary artery bypass grafting with radial artery use.

Nebivolol: vasodilator properties and evidence for relevance in treatment of cardiovascular disease

β-adrenergic blocking agents, a pharmacologically diverse class of cardiovascular medications, are recommended as first-line treatment for patients with hypertension and concomitant structural heart disease, and for angina and heart failure. Many within-class differences exist, from pharmacokinetics and pharmacodynamics to ancillary effects, such as intrinsic sympathomimetic activity, antiarrhythmic activity, α-1 adrenergic receptor blockade affinity, and direct vasodilation. Nebivolol is a third-generation, β1 selective, long acting β-blocker, which causes direct vasodilation via endothelium-dependent nitric oxide stimulation. The vasodilatory actions of nebivolol might result in clinical effects with some distinct properties. Differences from other β-blockers might include improvement of endothelial function, enhancement of forward flow in muscular resistance arteries, maintenance of exercise tolerance, and overall improved tolerability, side effect profile, and adherence. Nebivolol has been shown to be a clinically effective β-blocker for treatment as initial or add-on therapy for systemic hypertension, as an antianginal agent, and as therapy for patients with heart failure. These properties position nebivolol as a treatment option for patients with hypertension and/or structural heart disease, although its precise role in the therapeutic armamentarium remains to be clarified.