Technique historically cardiac ultrasound adopted

  • No School
  • AA 1
  • 360

This preview shows page 77 - 79 out of 360 pages.

Technique Historically, cardiac ultrasound adopted standard views in which the left side of the heart was portrayed on the right side of the ultrasound screen. There are two ways in which such cardiac-oriented images may be obtained. Figure 3.2 Position of the heart in the thoracic cavity with major axes (arrows). L, long axis; S, short axis. Courtesy of Dr. Manuel Colon, Hospital of the University of Puerto Rico, Carolina, PR. Diagnostic ultrasound 63 Cardiac ultrasound
Image of page 77

Subscribe to view the full document.

First, image in “cardiac mode” on the ultrasound machine, which will flip the screen image 180 degrees and will place the screen marker on the right of the image screen. Then place the probe with the marker to the patient’s left or pointing to the patient’s shoulders. More commonly, however, point-of- care sonographers leave the screen marker on the left as it is in abdominal imaging and place the probe marker to the patient’s right or pointing to the patient’s hips. Either way will generate the same image when looking at the screen. The second technique is described here. This allows the sonographer to keep the abdominal image settings on the machine the same, to avoid confu- sion, but the pictures generated will look identical to those made using cardiology settings and probe positioning. However, if the first option is preferred, just invert the probe positions described here by 180 degrees. Probe selection The probe used for cardiac ultrasound is most often a phased-array probe – ideally with the smallest possible footprint, useful in imaging between ribs. It is usually a lower-frequency probe with ranges between 2 and 5 MHz. Some machines also have cardiac presets in their setup menus that help the machine optimize digital image processing for cardiac imaging (such as altering dynamic range and contrast to enhance wall detection, and increas- ing frame rate for better detection of motion). Views Multiple ultrasound views are used to assess the heart at the bedside. The two views most commonly used by the non-cardiologist to look for contractility and evaluate for pericardial effusion are the subxiphoid four-chamber view and the left parasternal view. We review these two positions first, and then supplement with parasternal short-axis and apical four-chamber views to give the bedside ultrasonographer multiple options for evaluating the heart. Note that only the subxiphoid and apical views allow for four-chamber visualization and comparison of right and left ventricular cavity size. Subcostal/subxiphoid view The subxiphoid probe position uses the liver as an acoustic window through which the heart is well visualized. The probe should be placed in the subxiphoid position ( Figure 3.3 ). Aim toward the left shoulder and place the probe at a 15-degree angle to the chest wall. The probe indicator should be pointing toward the patient’s right ( Figure 3.4 ). Many novices place the probe at too steep an angle, and thus the ultrasound beam being generated is too steep – that is, it is not projecting toward the left chest cavity where the heart lies. In some people, the probe is almost
Image of page 78
Image of page 79
  • Fall '19

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask You can ask ( soon) You can ask (will expire )
Answers in as fast as 15 minutes