Intravenous Beta-blockade for Improvement of Autonomic Activity

Study Overview
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Brief Summary
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Chronic beta-adrenoceptor blockade is known to improve outcome of high risk patients whereas amelioration of autonomic activity was demonstrated to be a major cause of outcome improvement. Therefore, perioperative beta-adrenoceptor blockade is recommended in patients with Revised Cardiac Risk Index score of three or greater. The investigators hypothesise that preoperative intravenous beta-adrenoceptor blockade for treatment of hypertension and/or tachycardia improves autonomic activity reflected by increase of Total Power of Heart Rate Variability. Material and Methods: After IRB approval 20 patients scheduled for elective cardiac surgery were included into the study. Routine medication was continued throughout the study as recommended by the guidelines. HRV (TP and Low to High Frequency ratio (LF/HF) reflecting sympathetic to parasympathetic balance) was analysed prior to induction of general anesthesia and beta-adrenoceptor blockade in all patients (Baseline). Patients were assigned by their baseline hemodynamics. Patients with hypertension (systolic blood pressure > 140mmHg or diastolic blood pressure > 90mmHg) or tachycardia (heart rate > 80bpm) were assigned to group BETA-BLOCK. In this group metoprolol-boli (2mg) were administered intravenously in stepwise manner until hemodynamic values decreased to normal. Total dosage was recorded. After normalisation of hemodynamics, second HRV analysis was performed (Intervention). Normotensive and normocardic patients were assigned to group CONTROL. No intervention was performed. Statistics: Mann Whitney U test for comparison between groups and between events Baseline and Intervention within group BETA-BLOCK, p<0.05.

Official Title
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Beta-adrenoceptor Blockade Prior to Induction of Anesthesia for Improvement of Depressed Autonomic Regulation

Conditions
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Hypertension, Tachycardia, Heart Rate Variability

Intervention / Treatment
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* Drug: i.v. beta-blocker infusion (metoprolol)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients scheduled for coronary artery bypass surgery Ejection fraction > 30 % Informed consent Exclusion Criteria: Emergency cases Myocardiac infraction within 4 weeks

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 1<br>Patients with hypertension and/or tachycardia prior to induction of anesthesia requiring i.v. beta-blockade for treatment of raised hemodynamic | Drug: i.v. beta-blocker infusion (metoprolol)<br>* A beta-blocker (metoprolol) will be infused for treatment of hypertension and/or tachycardia prior to induction of anesthesia aiming at decrease of blood pressure and heart rate to normal limits<br>* Other names: Metorpolol, Lopresor(R);|
| 2<br>Patients with normal hemodynamic values prior to induction of anesthesia not requiring treatment | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Improvement of heart rate variability reflecting autonomic activity in the course of i.v. beta-blockade |  | Baseline, after i.v. beta-blockade, 6 months after discharge | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hospital stay, one-year cardiac mortality and morbidity after discharge |  | Postoperatively until discharge, between discharge and 1 year after discharge | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Outcome assessment, patients;, autonomic nervous system;, perioperative care;, adrenergic beta antagonist, Autonomic regulation, Perioperative beta-blockade, outcome