Effect of Gastric Bypass-induced Weight Loss on Myocardial Structure, Function and Metabolism
| Status: | Completed |
|---|---|
| Conditions: | Obesity Weight Loss, Gastrointestinal |
| Therapuetic Areas: | Endocrinology, Gastroenterology |
| Healthy: | No |
| Age Range: | 18 - 55 |
| Updated: | 5/5/2016 |
| Start Date: | July 2005 |
| End Date: | June 2014 |
Obesity affects more than 43 million Americans and is associated with an increased incidence
of heart failure, sudden death, and cardiovascular death. We have shown that increasing
obesity is independently associated with potentially detrimental LV structural and
functional, and metabolic changes. Thus in order to increase our understanding of the effect
of obesity on the heart, we wish to study the effect of significant weight loss on these
parameters.
of heart failure, sudden death, and cardiovascular death. We have shown that increasing
obesity is independently associated with potentially detrimental LV structural and
functional, and metabolic changes. Thus in order to increase our understanding of the effect
of obesity on the heart, we wish to study the effect of significant weight loss on these
parameters.
Thirty obese patients who weigh <350#, the weight limit of the PET table, who are to undergo
gastric bypass will be enrolled in this study. Written, informed consent approved by the
Institutional Review Board of Washington University School of Medicine will be obtained from
each subject before his/her participation in this study. Subjects will be compensated for
their time. Subjects will undergo Medical Screening (Visit 1) consisting of a comprehensive
medical evaluation: a history (questionnaire), physical examination, EKG, blood chemistries,
kidney function, complete blood count, lipid profiles and pregnancy tests for women of
childbearing age. Subjects who weigh < 300# will have fat-free mass (body composition)
determined by using a machine called DEXA. Measurement of Insulin Resistance (Visit 2):
Subjects will undergo a hyperinsulinemic/euglycemic clamp and nonradiolabeled glucose
infusion in order to define their level of insulin resistance and total body glucose
turnover. This study will be performed in the GCRC.
Measurement of Myocardial Metabolism, Efficiency, Structure, and Function Measures and Total
Body Fatty Acid Metabolism (Visit 3): Subjects will be admitted to the GCRC the evening
before the PET imaging and at 6 pm will receive a standard meal. The next morning an
18-gauge intravenous catheter will be inserted into your arm vein. A catheter (small tube)
will also be placed in the radial artery for the total body fat metabolism measurements &
for blood pressure monitoring. If the subject wishes it, they may have a Foley placed for
urination during the PET scan studies. Myocardial PET imaging. Studies will be performed
during fasting conditions at 8 am and ending at 1:00 pm. Each subject will be positioned
within the scanner, and a 2-min data collection will be acquired to verify proper
positioning before a 5-min. scan will be performed for generation of attenuation correction
factors. Heart blood flow, oxygen consumption, and measures of fat metabolism will be
obtained using PET imaging after the sequential injections of radiolabeled tracers as
reported previously by our group. Blood pressure and heart rate will be monitored
continuously and recorded throughout the image acquisition. During the scans, 5 blood
samples (0, 2, 10, 20,& 30 min) will be obtained for measurement of hormones, heart fuels
(e.g. fats, lactate) and carbon dioxide levels.
Anonymous Genetic Tissue and Data Sampling: Draw and store 1 tablespoon of subject's blood,
for a period of up to 10 years, to be used in future studies for screening for differences
in genes related to heart membrane proteins or heart energy metabolism (including but not
limited to genes known as KV1.5, KV2.1, PPAR, FATP, ACS, PGC-1). Echocardiography:
Immediately following the PET imaging for oxygen consumption determination, subjects will
undergo a complete 2D-, 3D-, and Doppler echocardiographic examination. Optison or Definity,
depending on availability, clinically used intravenous contrast agents may be administered
to aid with the acquisition of the ultrasound images. Total body fatty acid metabolism
measurements: Simultaneous with the PET imaging, the subjects will undergo an infusion of a
tracer amount of nonradioactive fat for measurement of total body fat metabolism. Blood
samples will be drawn at predetermined times for this measurement.
3 Months s/p Gastric Bypass Surgery (Visit 4). Blood sampling
1 Year s/p Gastric bypass Measurement of Body Composition, Blood Chemistries, Lipid Levels,
and Insulin Resistance (Visits 5 and 6). After the subjects have undergone gastric bypass
for clinical reasons and are weight stable for 2 weeks (after approximately 1 year
post-gastric bypass).
gastric bypass will be enrolled in this study. Written, informed consent approved by the
Institutional Review Board of Washington University School of Medicine will be obtained from
each subject before his/her participation in this study. Subjects will be compensated for
their time. Subjects will undergo Medical Screening (Visit 1) consisting of a comprehensive
medical evaluation: a history (questionnaire), physical examination, EKG, blood chemistries,
kidney function, complete blood count, lipid profiles and pregnancy tests for women of
childbearing age. Subjects who weigh < 300# will have fat-free mass (body composition)
determined by using a machine called DEXA. Measurement of Insulin Resistance (Visit 2):
Subjects will undergo a hyperinsulinemic/euglycemic clamp and nonradiolabeled glucose
infusion in order to define their level of insulin resistance and total body glucose
turnover. This study will be performed in the GCRC.
Measurement of Myocardial Metabolism, Efficiency, Structure, and Function Measures and Total
Body Fatty Acid Metabolism (Visit 3): Subjects will be admitted to the GCRC the evening
before the PET imaging and at 6 pm will receive a standard meal. The next morning an
18-gauge intravenous catheter will be inserted into your arm vein. A catheter (small tube)
will also be placed in the radial artery for the total body fat metabolism measurements &
for blood pressure monitoring. If the subject wishes it, they may have a Foley placed for
urination during the PET scan studies. Myocardial PET imaging. Studies will be performed
during fasting conditions at 8 am and ending at 1:00 pm. Each subject will be positioned
within the scanner, and a 2-min data collection will be acquired to verify proper
positioning before a 5-min. scan will be performed for generation of attenuation correction
factors. Heart blood flow, oxygen consumption, and measures of fat metabolism will be
obtained using PET imaging after the sequential injections of radiolabeled tracers as
reported previously by our group. Blood pressure and heart rate will be monitored
continuously and recorded throughout the image acquisition. During the scans, 5 blood
samples (0, 2, 10, 20,& 30 min) will be obtained for measurement of hormones, heart fuels
(e.g. fats, lactate) and carbon dioxide levels.
Anonymous Genetic Tissue and Data Sampling: Draw and store 1 tablespoon of subject's blood,
for a period of up to 10 years, to be used in future studies for screening for differences
in genes related to heart membrane proteins or heart energy metabolism (including but not
limited to genes known as KV1.5, KV2.1, PPAR, FATP, ACS, PGC-1). Echocardiography:
Immediately following the PET imaging for oxygen consumption determination, subjects will
undergo a complete 2D-, 3D-, and Doppler echocardiographic examination. Optison or Definity,
depending on availability, clinically used intravenous contrast agents may be administered
to aid with the acquisition of the ultrasound images. Total body fatty acid metabolism
measurements: Simultaneous with the PET imaging, the subjects will undergo an infusion of a
tracer amount of nonradioactive fat for measurement of total body fat metabolism. Blood
samples will be drawn at predetermined times for this measurement.
3 Months s/p Gastric Bypass Surgery (Visit 4). Blood sampling
1 Year s/p Gastric bypass Measurement of Body Composition, Blood Chemistries, Lipid Levels,
and Insulin Resistance (Visits 5 and 6). After the subjects have undergone gastric bypass
for clinical reasons and are weight stable for 2 weeks (after approximately 1 year
post-gastric bypass).
Inclusion Criteria:
- Subjects that will undergo gastric bypass surgery will be included in the study.
Exclusion Criteria:
- Subjects who have a history of insulin-requiring diabetes, ≥Class II hypertension,
cardiac disease, major systemic disease, of smoking cigarettes with in the last 12
months, who are pregnant or taking vasoactive or lipid-lowering medications will be
excluded because these conditions may affect our cardiac endpoints. Subjects unable
to give informed consent will be excluded. Subjects > 350# (the weight limit of the
PET table) will be excluded.
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