Acute Myocardial Infarction
Conditions
Keywords
exercise, neuromodulation, blood flow, exercise capacity
Brief summary
The investigators will test the hypothesis that transcutaneous electrical nerve stimulation (TENS) may attenuate peripheral vasoconstriction and to improve blood flow redistribution during handgrip exercise in acute myocardial infarction (AMI) patients after Coronary Arterial Bypass Graft Surgery (CABG).
Detailed description
Thirty-eight patients will be randomized to a (4 times/day; 30 min/session) for 5-day program of TENS (n = 20) or to placebo-TENS (P-TENS, n = 18) applied on cervical region (C7-T4). Acute sympathetic stimulation by cold pressor test (CPT), Maximal voluntary contraction (MVC), Femoral blood flow (FBF) and femoral vascular conductance (FVC) will be measured as primary outcome pre and post-CABG, even as the 6-minute walk test (6-MWT), Inspiratory and expiratory muscle strength (PImax and PEmax) and β-endorphin as a secondary clinical parameters. In addition, amount of opioid analgesic and pain intensity also will be measured throughout at first 24 hours after CABG (immediately, 6, 12 and 24 hours).
Interventions
DEVICETranscutaneous electrical nerve stimulation
Patients will be treated with conventional TENS (ENDOMED 684 Device, ENRAF-Nonius B.V., Rotterdam, Netherlands) for 5 days (4 times/day; 30 min/session) applied on cervical region (C7-T4). TENS intervention was applied as described elsewhere.
Sponsors
University of Brasilia
Hospital Sao Joao
Hospital de Clinicas de Porto Alegre
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Investigator)
Eligibility
Sex/Gender
ALL
Age
48 Years to 70 Years
Healthy volunteers
No
Inclusion criteria
* a previous history of more than 1 vessel coronary artery disease, * lifelong abstinence from tobacco, and * formal indication for CABG, according to established guideline.
Exclusion criteria
* Patients older than 70 years of age, with chronic renal failure, or with unstable angina in the 48 h prior to CABG, moderate or severe valve disease, complex cardiac arrhythmias, stroke, and/or inability to exercise the lower limbs.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Blood flow redistribution - baseline and 5 days later | 1 day | The ultrasound Doppler system will be equipped with two linear array transducers operating at an imaging frequency of 7- 8 megahertz (MHz). The common femoral artery of the left leg will be insonated distal to the inguinal ligament, 2-3 cm proximal to the bifurcation. Using femoral artery diameter and mean blood velocity (MBF), femoral blood flow (FBF) was calculated as MBF π x (vessel diameter/2)2 x 60. Femoral vascular resistance (FVR) and femoral vascular conductance (FVC) were calculated as (MBP/FBF) and (FBF/MBP \* 100 mm Hg), the conductance multiplied by 100 mmHg so that the conductance units will be similar to the units of femoral blood flow (10, 45). The magnitude of reduction FVC (expressed in %) was calculated as vascular conductance during exercise (% change) - conductance at rest (% change) expressed by % of baseline. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Inspiratory and Expiratory Muscle Function | 5 day | Inspiratory and expiratory muscle strength testing were performed using a pressure transducer (MVD-500 V.1.1 Micro Hard System, Global Med, Porto Alegre, Brazil). Maximal inspiratory (PImax), and maximal static expiratory pressure (PEmax) were measured as previously described. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Pain Intensity | 5 day | A visual analog scale (VAS) for assessing current pain intensity will be used to evaluate pain from 0 to 10, where 0 means no pain and 10 indicates severe pain, being applied on the first and on the 5th day after CABG . |
| Opioid Analgesic Amount | 5 day | During the first 24 h (immediately, 6, 12 and 24 h) after CABG, the amount of additional analgesic dose (pethidine hydrochloride (HCl) 20 mg, maximum 1 mg/kg/day) was measured for patients in both groups. |
| β-Endorphin Analysis | 5 day | Ten milliliters of venous blood will be taken by the phlebotomist. 3 ml of which will be stored in ethylenediaminetetraacetic acid (EDTA) for analysis of a differential white cell count. Seven ml of blood will be divided between an EDTA tube and a lithium heparin (LH) gel tube. These blood samples will be centrifuged and frozen until assayed. β-endorphin was measured by sandwich enzyme immunoassay (ELISA) kit (Phoenix Pharmaceuticals, Inc., USA). |
Countries
Brazil
Outcome results
None listed