EFFECT OF POST-MI EXERCISE TRAINING ON

CARDIAC REMODELING AND FUNCTION

UNIVERSITY OF TEXAS AT SAN ANTONIO

CARDIOVASCULAR FITNESS – DR. ZHANG

BY: KAYLA FLOYD AND CASTURAL THOMPSON II

MYOCARDIAL INFARCTION

• Definition (National Library of Medicine)• Commonly known as a heart attack that occurs when blood flow to the heart is blocked for a period of time

where the muscle becomes damaged or dies.

• Signs and Symptoms (National Library of Medicine)

• Chest pain

• Pressure, squeezing, or pain

• Shortness of breath

• Discomfort in the upper body

• Arms, shoulder, neck, or back

• Nausea, vomiting, dizziness, lightheadedness, and/or sweating

MYOCARDIAL INFARCTION

• Statistics

• 565,000 new cases and 300,000 recurrent cases of MI annually

• People older than 65 have a higher prevalence rate

• More likely to occur in males

• Most victims died before arriving to the hospital

• Is one of the top 5 most expensive conditions for inpatient hospitalization visits in the U.S., approximately $11.5 billion

http://www.ncsl.org/research/health/chronic-disease-prevention-and-health-promotion.aspx

EFFECTS OF EXERCISE ON CARDIAC

REMODELING

CARDIAC REMODELING

Learning Objectives:• Remodeling

• Duration

• Intensity

• Frequency

REMODELING

• ANF – atrial natriuretic factor• Biological marker to signal ventricular overload

• Increased secretion of peptides

• Cascading effect

• 3 detrimental influences to the heart

1. Left Ventricular hypertrophy

2. Dilation

3. Collagen accumulation

TYPES OF HEART FAILURE

INTENSITY, FREQUENCY, AND DURATION

INTENSITY

• Cannistra et al (1999): Moderate-high intensity exercise training after myocardial infarction: effect on left ventricular remodeling.

• 12 week aerobic training program

• Slight variation within the experimental group

• Rognmo et al (2012): Cardiovascular risk of high-versus moderate-intensity aerobic exercise in cornonary heart disease patients.

• 6 week training program at high intensities

• There was a reduction in cardiovascular episodes

• Risk: increased chances for the recurrence of MI or death

FREQUENCY

• Nielwand et al (2000): Differential effects of high-frequency versus low-frequency exercise training in rehabilitation of patients with coronary artery disease.• 6 week 2 hrs per week training program

• High frequency: 10 per week

• Low frequency: 2 per week

• Higher frequency is associated with functional capacity

• Quality of life

DURATION• La Rovere, Bersano, Gnemmi, Specchia, &

Schwartz (2002): Exercise-induced increase in baroreflex sensitivity predicts improved prognosis after myocardial infarction.

• 4 week aerobic exercise regimen

• Decreased cardiovascular mortality by 26%

• Reduced total cholesterol, triglycerides, and blood pressure

• Lee et al (2008): Effect of cardiac rehabilitation on myocardial perfusion reserve in postinfarction patients.

• Increased oxygen consumption

• Increased cardiac output

• Increased regional blood flow

• Increased gene expression

EFFECTS OF EXERCISE ON CARDIAC

FUNCTION

CARDIAC FUNCTION

Learning Objectives:• Contractility – Ca 2+ Sensitivity

• Baroreflex Sensitivity

• Gene and Protein Expression

• ACE

CONTRACTILITY – CA2+ SENSITIVITY

• Post-MI patients are at increased risk:

1. Tachycardia

2. Instability in electrical conductance

3. Disturbance in action potential

BONILLA ET AL (2012): ENDURANCE EXERCISE TRAINING NORMALIZES REPOLARIZATION AND CALCIUM-HANDLING ABNORMALITIES, PREVENTING VENTRICULAR FIBRILLATION IN A MODEL OF SUDDEN CARDIAC DEATH.

• Exercise:

1. Stablized QTc intervals

2. Reduction action potential duration at 50% and 90% repolarization

3. Restored Ca2+ spark frequency to levels similar to control

BAROREFLEX SENSITIVITY

• A depression of <3ms/mm Hg has been shown to increase mortality

GENE AND PROTEIN EXPRESSION

• SERCA2a

• ANP

• NCX1 expression

• PLN

• TIMP-1 levels and MMP-1/TIMP-1

• eNOS

ACE

• MI causes an increase in ACE and renin levels

• Potent vasoconstrictor

• ACE2 also increases

• Burrell et al (2005): Myocardial infarction increases ACE2 expression in rat and humans.

• Wan et al (2007): Effect of post-myocardial infarction exercise training on the renin-angiotensin-aldosterone system and cardiac function.

FUTURE STUDIES • Study design

• More women

• Incorporate elderly people

• Longitudinal

• Endurance & resistance training

• Stem cells

http://www.youtube.com/watch?v=vTjc5brpY7A

STEM CELLS (PERIN ET AL, 2004)

Questions?