The safety and effectiveness of esmolol in the perioperative period in patients undergoing abdominal aortic surgery

Blood Pressure Recovery After Dobutamine Antagonism: Partial With Landiolol, None With Esmolol

We investigated the hemodynamic effects of 2 short-acting β₁ -blockers, landiolol and esmolol, in the continuous presence of dobutamine in a prospective, single-center, randomized, crossover study in 16 healthy White volunteers. Dobutamine was infused at a rate sufficient to increase the heart rate by at least 30 beats per minute, followed by a 60-minute infusion of 50 μg/kg/min esmolol or 10 μg/kg/min landiolol on top of the unchanged dobutamine infusion. Concentrations of β-blockers and their metabolites in blood, heart rate, and blood pressure were followed for 180 minutes. Landiolol reduced the dobutamine-induced heart rate and blood pressure increases better than esmolol. After discontinuation of β-blocker administration, heart rate recovered swiftly to preinfusion values in both study arms. Systolic and diastolic blood pressure recovered partially after landiolol but showed a continued reduction after esmolol. No serious adverse events were observed. The heart rate effect is characteristic for β-blockers, whereas the blood pressure effects are likely due to direct and indirect β-blocker effects as well as influences on various ion channels. This may explain why landiolol that is devoid of effects on renin and sodium, calcium, and potassium channels behaves different from esmolol with respect to blood pressure recovery.

Dobutamine Alters the Pharmacokinetic and Pharmacodynamic Behavior of Esmolol

Background and objective

This study involved an investigation into the pharmacokinetic and pharmacodynamic behavior of esmolol in the presence of dobutamine in healthy subjects of European ancestry.

Methods

We conducted a single-center, prospective randomized study of 16 healthy subjects with each receiving an infusion of dobutamine sufficient to increase heart rate (HR) by 30 beats per minute (bpm) followed by a 60-minute infusion of 50 µg/kg/min esmolol. Pharmacokinetics, HR, and blood pressure were evaluated for 180 minutes.

Results

In the presence of dobutamine, esmolol elimination was substantially faster than without dobutamine, Esmolol infusion reduced dobutamine-induced elevation of HR reversibly whereas the dobutamine-induced systolic blood pressure (SBP) reduction did not recover after the termination of the esmolol infusion. No serious adverse events (AEs) were observed.

Conclusions

The accelerated elimination of esmolol was likely due to higher cleavage through tissue esterases induced by dobutamine-induced increased tissue passage cycles per time unit. The HR effect was characteristic of a beta-blocker, whereas the blood pressure effect was likely due to a mechanism other than direct beta-blockade. HR remained elevated after the infusion of esmolol and dobutamine, most likely due to persistent blood pressure reduction.

Pharmacodynamic and -kinetic Behavior of Low-, Intermediate-, and High-Dose Landiolol During Long-Term Infusion in Whites

Pharmacokinetics, pharmacodynamics, safety, and tolerability of long-term administration of landiolol, a fast-acting cardioselective β-blocker, were investigated for the first time in white subjects in a prospective clinical trial. Blood concentrations of landiolol and its metabolites, heart rate (HR), blood pressure (BP), and electrocardiogram parameters were studied in 12 healthy volunteers receiving continuous infusions of a new 12-mg/mL formulation of landiolol using a dose-escalation regimen (10 μg/kg BW/min for 2 hours, 20 μg/kg BW/min for 2 hours, 40 μg/kg BW/min for 20 hours, 6 hours follow-up). Landiolol blood concentrations were dose proportional. Time until steady state decreased with increasing doses. Pharmacokinetic parameters were t1/2 = 4.5 minutes, VD = 366 mL/kg, and total body clearance = 53 mL·kg·min. Maximal blood concentrations of the inactive main metabolite M1 were 10-fold higher than those of landiolol, with t1/2 = 126 minutes, VD = 811 mL/kg, and total body clearance = 4.5 mL·kg·min. HR reduction from baseline was fast (significant after 16 minutes) and sustained throughout the administration period. Systolic and diastolic BP reductions and electrocardiogram parameter changes were less pronounced and became significant only occasionally. Recovery after discontinuation of infusion was fast with little (HR) or no (BP) rebound. The new formulation showed excellent local and general tolerability.

Comparison of the β-Adrenergic Receptor Antagonists Landiolol and Esmolol: Receptor Selectivity, Partial Agonism, and Pharmacochaperoning Actions

Blockage of β1-adrenergic receptors is one of the most effective treatments in cardiovascular medicine. Esmolol was introduced some three decades ago as a short-acting β1-selective antagonist. Landiolol is a more recent addition. Here we compared the two compounds for their selectivity for β1-adrenergic receptors over β2-adrenergic receptors, partial agonistic activity, signaling bias, and pharmacochaperoning action by using human embryonic kidney (HEK)293 cell lines, which heterologously express each human receptor subtype. The affinity of landiolol for β1-adrenergic receptors and β2-adrenergic receptors was higher and lower than that of esmolol, respectively, resulting in an improved selectivity (216-fold versus 30-fold). The principal metabolite of landiolol (M1) was also β1-selective, but its affinity was very low. Both landiolol and esmolol caused a very modest rise in cAMP levels but a robust increase in the phosphorylation of extracellular signal regulated kinases 1 and 2, indicating that the two drugs exerted partial agonist activity with a signaling bias. If cells were incubated for ≥24 hours in the presence of ≥1 μM esmolol, the levels of β1-adrenergic-but not of β2-adrenergic-receptors increased. This effect was contingent on export of the β1-receptor from endoplasmic reticulum and was not seen in the presence of landiolol. On the basis of these observations, we conclude that landiolol offers the advantage of: 1) improved selectivity and 2) the absence of pharmacochaperoning activity, which sensitizes cells to rebound effects upon drug discontinuation.

Combined use of ultra-short acting β-blocker esmolol and intravenous phosphodiesterase 3 inhibitor enoximone

In patients with impaired myocardial contractility associated with downregulation of the beta-receptors, compounds inhibiting phosphodiesterase (PDE) 3 may be useful to increase contractility. The PDE3 inhibitor enoximone has been shown to improve pump-function independent from the beta-receptor pathway. A simultaneous decrease in ventricular preload and afterload by vasodilation has led to the term 'inodilator'. Esmolol is the only available ultra-short acting intravenous beta-blocking agent. Due to its half-life of approximately 9 min, beta-blockade, and thus, heart rate, can easily be titrated. Esmolol appears to be a helpful tool to avoid myocardial ischemia (e.g., in the perioperative setting). As with all other beta-blockers, it has dose-dependent negative inotropic effects, and this limits its use in patients with severe heart failure showing low cardiac output. It seems reasonable that an intravenous combination of both approaches, enoximone-induced positive inotropy and esmolol-associated protection from myocardial ischemia, might offer advantages by producing beneficial hemodynamic effects and by compensating each other's limitations in a complementary way. In spite of some promising results, the place of a combination of enoximone and esmolol in the process of treating patients with (acute) heart failure showing low output is still not entirely clear, and needs further confirmation.

[Preoperative betablockers use in vascular and thoracic surgery]

OBJECTIVE

The aim of this study was to evaluate betablockers use and effect in the preoperative period in vascular and thoracic surgery.

PATIENTS AND METHODS

Retrospective study concerning patients scheduled for high or intermediate surgical risk procedure (n = 321) in a French vascular and thoracic surgery department during 2002. Eligibility for betablocker therapy was defined as previously described for inclusion criteria in Mangano's Study (N Engl J Med 1996;335:1713-20). Therapy effect was evaluated with heart rate in the operating room.

RESULTS

Forty-six percent (99/213) of eligible patients for betablockers were really treated in the preoperative period. In patients treated with betablockers, 40% appeared in the operating room with the most favorable heart rate (55-65 b/min). During surgical procedure, heart rate over 80 b/min was observed in more than 30% of patients with betablocker therapy. In patients eligible for betablocker therapy but untreated with these drugs, only 12% have received betablockers in the preoperative period.

CONCLUSION

Betablockers underuse is important in the preoperative period, and effect on heart rate is rarely optimal. This fact should encourage physicians to apply protocols for perioperative betablockers administration.

Aortic emergencies

Prompt recognition of actual or impending aortic emergencies is essential to the effective practice of emergency medicine. Understanding the pathophysiologic principles and awareness of the potential subtleties in the clinical presentations of aortic dissection, aneurysm, and occlusive disease are prerequisites to this task. Knowledge of current diagnostic modalities is also important if these entities are to be identified rapidly and managed efficiently to maximize the potential for a good patient outcome. Awareness of the potential complications of these conditions and the necessary interventional and resuscitative measures that might be called for in the appropriate clinical setting are likewise essential requirements for the EP. Appropriate surgical consultation and mobilization of operative resources form the backbone of appropriate management in the patient who has an aortic emergency.

Resistant hypertension, secondary hypertension, and hypertensive crises

Resistant hypertension, secondary hypertension, and hypertensive crises are uncommon but potentially dangerous forms of hypertension that are associated with an increased risk of complications such as myocardial infarction, heart failure, stroke, and renal failure. Appropriate diagnostic screening and selective drug or surgical management can reduce the risk of these complications dramatically. In compliant patients, resistant hypertension occurs most often in obese patients receiving inadequate diuretic therapy. In patients with clinical clues to the diagnosis, the best current screening test for renovascular hypertension is probably the ACE-inhibitor renal scintiscan. Angioplasty is considerably more successful in younger patients with fibrous dysplasia than in older patients with the atherosclerotic variety. Hypertensive crises are divided into BP urgencies and emergencies. In both settings, the reduction in BP should generally be gradual rather than abrupt, with no intent to acutely normalize the BP.

The effect of an infusion of esmolol on the incidence of myocardial ischaemia during tracheal extubation following coronary artery surgery

The aim of this randomised controlled study was to determine whether an esmolol infusion affected the incidence of ST segment changes during weaning from intermittent positive pressure ventilation and tracheal extubation after coronary artery surgery. Thirty-one patients received an infusion of esmolol 0-300 microg x kg(-1) x min(-1) and 37 patients comprised the control group. ST segment changes were monitored using a continuous ambulatory surveillance system. The electrocardiogram, direct arterial pressure and pulse oximetry were monitored continuously. The period of analysis was from 120 min before until 180 min after tracheal extubation. Three patients in the esmolol group developed myocardial ischaemia during the study period compared with 12 in the control group (p = 0.05). Heart rate increased with time during the study period (p = 0.002) in the control group but was unchanged in the esmolol group. Mean heart rate was significantly higher in the control group than in the esmolol group from 40 min before until 180 min after tracheal extubation. Seven patients in the esmolol group suffered adverse events related to the esmolol infusion. Although the use of esmolol reduced the incidence of myocardial ischaemia, the incidence of adverse effects makes it unsuitable prophylaxis for patients after coronary artery surgery.

Treatment of Perioperative Myocardial Ischemia

Prevention and treatment of myocardial ischemia re mains a central focus of perioperative care. Myocardial ischemia is best understood in terms of myocardial oxygen supply and demand ratios. Conventional ther apy includes nitrates, β-blockers, and calcium channel blockers. In all 3 drug classes, ischemia is reduced by either improving supply, decreasing demand, or both. More recent investigation evaluates these medications either as prophylactic therapy or as a component of long-term risk reduction for cardiac morbid events. Newer therapies, including anticoagulation, pain ther apy, normothermia, central neuroaxial techniques, and other therapies, are reviewed.