Aortic-Radial Pressure Gradients Post CPB
Condition: Coronary Artery Disease
MeSH terms: Coronary Artery Disease
Study type: Observational

Summary: 
      This study will examine whether pre-operative, non-invasive arterial stiffness measurements
      can be used to predict which patients will develop an aortic-to-radial pressure gradient
      after coronary artery bypass graft (CABG) surgery. A previous small study by Kanazawa, et al.
      demonstrated in patients who developed an aortic-to-radial pressure gradient after CABG
      surgery, the pulse wave velocity (PWV) was higher in the aorta and decreased when moving
      toward the radial artery. In the patients who did not develop a pressure gradient, the PWV
      started lower in the aorta and increased when moving towards the periphery.

      The purpose of this investigation is to examine whether pre-operative PWV measurements can be
      used to identify patients who will develop an aortic to radial pressure gradient after CABG
      surgery.

      Applanation tonometry will be performed on the right carotid and femoral arteries to assess
      carotid-femoral pulse wave velocity, a surrogate for aortic stiffness. (SphygmoCor system,
      AtCor Medical, Sydney, Australia). The measurement will be obtained before induction of
      general anesthesia in the presurgical area. Also in the presurgical area, a non-invasive
      cardiac output (CO) measurement will be obtained by using the ICON Device (Osypka Medical, La
      Jolla, California). This CO value will be used to compare to the CO values obtained
      invasively in the operating room.
    

Detailed description: 
      The purpose of the study is determine if there is a relationship between pre-operative
      vascular characteristics including, carotid-femoral pulse wave velocity (cfPWV), Augmentation
      Index(AI) and central aortic pressure, and the development of a pressure gradient between the
      aorta and radial artery after cardiopulmonary bypass.

      The procedures necessary to achieve the desired outcomes are as follows. The first
      measurement made by the research team will be pre-operative cardiac output (CO) measurement.
      The ICON device is a non-invasive device that measures CO, or the amount of blood that your
      heart pumps per minute. This device utilizes four stickers that are attached to skin, two on
      the left side of the neck and two located on the left side of the chest. These stickers
      function similarly to electrocardiogram (EKG) stickers that measure the electrical activity
      of your heart. After attachment of the stickers, the ICON device will be used to make a
      measurement of CO, which takes 1-2 minutes. After the measurement, the stickers will be
      removed and the ICON device will not be used again in the study.

      Secondly, pre-operative cfPWV, AI, and central aortic pressure measurements will be made. The
      Sphygmocor device will be utilized to make the pre-operative cfPWV, AI and central aortic
      pressure measurements. First, the AI measurements will be made using a non-invasive blood
      pressure cuff placed on the right arm. The patient's blood pressure will be measured twice in
      a row with this special blood pressure cuff. The blood pressure cuff on the right arm will be
      removed and then a cuff will be placed around the right thigh. Measurements will be made with
      a paper ruler from the patient's neck to the cuff on their leg. To make the cfPWV
      measurements, the cuff on the thigh will inflate while a pressure probe will be placed on the
      skin of the patient's right neck. Four measurements of cfPWV will be made with this
      technique.

      The intraoperative central aortic pressure measurement will be accomplished with the help of
      the cardiothoracic surgeon. The surgeon will place a catheter in the aorta as part of the
      coronary artery bypass grafting surgery. This catheter will be connected to the artificial
      heart-lung machine. Prior to turning on the heart-lung machine, the pressure in the aorta
      will be measured with this catheter. This is the standard of care for this type of surgery
      and will not delay the surgery. After the artificial heart-lung machine is turned off but
      before the catheter is removed from the aorta, the pressure will once again be measured.

      In order to measure intraoperative CO values, we will utilize the pulmonary artery (PA)
      catheter that was placed at the beginning of the surgery.. The patient will have a catheter
      placed in the right side of the neck that will travel through the heart and into a branch of
      the artery that goes from the heart to the lungs. This catheter will have the ability to
      measure the amount of blood that is pumped from the heart per minute. At the same times that
      the pressure in the aorta is measured (as above), the amount of blood that is pumped from the
      heart per minute will be measured.

      Lastly measurement of peripheral artery blood pressure will be accomplished with a right
      radial arterial catheter. Prior to the start of surgery, the patient will receive a special
      catheter in the radial artery of their right arm. This is the standard of care for blood
      pressure monitoring in this type of surgery. At the same times during the surgery that the
      pressure is being measured from the aortic catheter, the pressure will be measured from the
      catheter in the right radial artery.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The study population will include adult patients aged 40-80 years old who are scheduled to
        undergo elective on-pump coronary artery bypass graft (CABG) surgery.
      
Keywords: Coronary Artery Bypass Graft (CABG), Arterial stiffness