Study: NCT01048125

Intervention type: DEVICE
Group type: ACTIVE_COMPARATOR
Intervention: Sympathetic Nerve Activity
Description: Resting Sympathetic Nerve Activity

Intervention type: DEVICE
Group type: EXPERIMENTAL
Intervention: Sympathetic Nerve Activity
Description: Resting Sympathetic Nerve Activity

Intervention type: BEHAVIORAL
Group type: ACTIVE_COMPARATOR
Intervention: Mental Stress Test (Color Word Test)
Description: A printed word will be shown to the subject, displayed in a color different from the color it actually names. The subject will be asked to say the color that the word is printed in as quickly as possible. For example if the word green is written in blue ink, they will say blue. This mental stress procedure will be used to cause brief changes in heart rate and blood pressure.

Intervention type: BEHAVIORAL
Group type: EXPERIMENTAL
Intervention: Mental Stress Test (Color Word Test)
Description: A printed word will be shown to the subject, displayed in a color different from the color it actually names. The subject will be asked to say the color that the word is printed in as quickly as possible. For example if the word green is written in blue ink, they will say blue. This mental stress procedure will be used to cause brief changes in heart rate and blood pressure.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: The Modified Oxford Technique for Baroreflex Sensitivity
Description: Sodium nitroprusside (100 µg) will be infused intravenously as a bolus, followed 60 seconds later by a bolus of phenylephrine hydrochloride (150 µg). Infusion of nitroprusside will decrease blood pressure approximately 10-15 mmHg below baseline values. Subsequent phenylephrine infusion will increase blood pressure approximately 10-15 mmHg above baseline values. Nitroprusside and phenylephrine have been used extensively to assess baroreflex sensitivity in healthy as well as heart failure populations. Additionally, the dosages being used have been shown to minimize the risk of excessive decreases or increases in blood pressure.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: The Modified Oxford Technique for Baroreflex Sensitivity
Description: Sodium nitroprusside (100 µg) will be infused intravenously as a bolus, followed 60 seconds later by a bolus of phenylephrine hydrochloride (150 µg). Infusion of nitroprusside will decrease blood pressure approximately 10-15 mmHg below baseline values. Subsequent phenylephrine infusion will increase blood pressure approximately 10-15 mmHg above baseline values. Nitroprusside and phenylephrine have been used extensively to assess baroreflex sensitivity in healthy as well as heart failure populations. Additionally, the dosages being used have been shown to minimize the risk of excessive decreases or increases in blood pressure.

Intervention type: OTHER
Group type: ACTIVE_COMPARATOR
Intervention: Cold Pressor Test
Description: The subject will be asked to place their hand in ice water for 2 minutes. This procedure will be used to cause transient changes in sympathetic nerve activity, heart rate and blood pressure.

Intervention type: OTHER
Group type: EXPERIMENTAL
Intervention: Cold Pressor Test
Description: The subject will be asked to place their hand in ice water for 2 minutes. This procedure will be used to cause transient changes in sympathetic nerve activity, heart rate and blood pressure.

Intervention type: DEVICE
Group type: ACTIVE_COMPARATOR
Intervention: Echocardiographic evaluation
Description: Transthoracic echocardiography with 2D, color and pulse Doppler will be employed in all of our subjects. Baseline left ventricular function, systolic as well as diastolic, will be quantified.

Intervention type: DEVICE
Group type: EXPERIMENTAL
Intervention: Echocardiographic evaluation
Description: Transthoracic echocardiography with 2D, color and pulse Doppler will be employed in all of our subjects. Baseline left ventricular function, systolic as well as diastolic, will be quantified.