The Technically Difficult Echocardiogram
©Walter Rasmussen, R.D.C.S.
“Technically difficult echocardiogram,” is a catch phrase for any Echo study that is suboptimal in image quality.
Factors that increase the difficulty of performing and echocardiography examination and attributed to the patient’s physique are generally referred to as, “Body Habitus”. Other causes for difficult exams relate to prior surgery, acquired disease, or congenital defects.
Obese individuals can be more difficult to image due to attenuation of the signal over the longer distance, but this is not always the case because some obese individuals have little or no fat on the chest area while others have fat tissue which seems to conduct ultrasound very well, despite the increased distance.
If imaging is difficult, breathing maneuvers, including the suspension of breath where the images look best with either inhalation or exhalation can help. Obese individuals and patients with large breasts can sometimes image better when scanned while lying in a supine position. IV ultrasound contrast is very useful when there is poor definition of the left ventricular chamber and walls.
Slender individuals can be very difficult to image because the ribs are more prominent and there is little subcutaneous fat, presenting a flat, bony surface, resulting in poor probe contact.
Finding a good apical window with a slender patient can be very difficult because the probe often must be oriented at an extreme angle, not allowing its face to come into full contact with the skin. In this case, liberal amounts of ultrasound gel can be very useful for bridging gaps between the probe and the skin. Repeated applications of gel are usually necessary because a large mass of gel does not retain its cohesion as it warms or the when the probe position is changed. Respiratory maneuvers can also be very helpful with some asthenic patients.
Dextrocardia and Cardiac Dextroposition:
Dextrocardia is a congenital defect where the heart is located in the right side of the chest with the axis of the heart tilted in the opposite direction, the base toward the left shoulder and the apex toward the right hip. In cardiac dextroposition, the heart is on the right side of the chest usually due to a condition where the heart is pushed by lung tissue, fluid accumulation or surgery such as lung lobectomy. In these conditions, the parasternal long axis view of the heart might be found as high as the first intercostal space on the right side of the chest.
For the sake of thoroughness, it is important to begin the exam with the patient lying on their left side however, for right-sided displacement, it is almost always necessary to then turn the patient steeply to their right side in order to get the best images.
In this condition, the lungs may expand and encroach upon the already small windows that are available. Some individuals with lung disease actually image quite well, while others are extremely difficult even to the point of requiring the use of contrast, which may or may not be effective. With lung disease, is not uncommon that the heart is pushed toward the diaphragm and so, a low parasternal or even the subcostal window can be the best place to find the standard parasternal and apical views.
Surgery causes scarring and displacement of organs which interferes with the uniform penetration of the ultrasound beam across the sector. Implants can cause reflection, dispersion or attenuation of the ultrasound beam.
If there is scar tissue and the image is sub-optimal, try moving slightly off the scarred area and changing transducer angulation to compensate. The image may also be improved by having the patient inhale or exhale in order to move the area of interest into view.
The most common surgeries encountered while performing Echocardiography are heart surgery and transplant, pneumonectomy (removal of a lung or lobe), lung transplant, aortic graft, breast implant or mastectomy, and abdominal surgery.
Breast implants are notorious for blocking the apical views of the heart. Working with the breath can greatly improve the images in some, but not all cases by moving the probe laterally with exhalation and mediallly/inferiorly with inhalation. Have the patient hold her breath at the point of respiration when the image has the greatest clarity.
When a portion of the right or left lung has been removed, the heart tends to drift toward the empty space and it can therefore be valuable to know which lung has been removed. Subcostal imaging for the purpose of establishing the heart’s location can be very helpful in these cases and it is sometimes the only view of the heart that can be found. Imaging the patient in the supine or right lateral positions can also help.
In the hospital setting it is not uncommon to encounter patients whose acoustic windows are covered with monitoring electrodes, bandages or a defibrillator pad.
The nurse in attendance may be able to temporarily remove an obstruction. It is important to clean the probe before using it, especially on areas with healing incisions. If an incision is fresh or unhealed, it is best to avoid direct contact with it. Cover the probe with an approved transducer cover to help prevent infection and probe contamination. In the event of uncertainty, consult the nurse in attendance for advice. Using a transducer cover requires that some ultrasound gel be squeezed inside of the cover which is then pulled tightly over the face of the probe sufficient to provide air-free contact with the transducer. Ultrasound gel is applied to the exterior of the probe cover in order to provide good probe/patient contact. There is no significant loss of image quality from using an ultrasound probe cover. Sterile gloves work quite well as probe covers.
If the presence of bandages or other obstructions have prevented the acquisition of a view, an annotation should be made so that the reader knows why it was omitted.
Liver surgery can greatly limit subcostal views, making it difficult to find the IVC, abdominal aorta and subcostal 4-chamber view. If there is difficulty finding the inferior vena cava, start at the maximum depth setting because in these patients, hepatomegaly can cause it to be a lot farther from the abdominal wall than normal. It can be helpful to use Color Doppler set for low velocities as an aid to finding the vessel. Having the patient inhale and then holding their breath while searching is almost always helpful for clarifying subcostal views.
In difficult cases, the IVC can be located by turning the transducer transversely in order to search for it in its short axis, in which case it will appear as a small, dark sphere, distinguishable from all the other vessels by its relative larger size and the influence respiration has upon its diameter. Once the IVC has been located in the transverse view, carefully rotate the transducer counter clockwise until the standard long-axis view of it is obtained. Store a freeze frame with a notation if the view was unsuccessful.