Contrast Echo Flashcards
Saline Contrast Echo
Intravenous injection of microbubbles to opacify the cardiac chambers or evaluate myocardial perfusion is called __________
contrast echocardiography
Agitated saline contrast opacifies the _____ and is used for detection of _________based on the appearance of contrast in the left heart.
right heart
right to left intracardiac shunting
Smaller microbubbles size _____ in diameter transverse the _______ vasculature, allowing left heart chamber and myocardial opacification.
1-5 micrometer
pulmonary
1mm = micrometer [µm]
1000 [µm]
What are the indications for the use of agitated saline for right heart opacification?
- TIA (transient ischemic attack) - usually resolve within 48 hrs
- CVA (cerebrovascular accident) - last longer than 48hrs and cause damage
- suspect septal defect (ASD/VSD)
What is the contraindication for the use of agitated saline for right heart opacification?
pregnant women
Use of _________ is not recommended in women who are pregnant
bacteriostatic saline
Bacteriostatic saline is a physiological saline solution containing the bacteriostatic agent benzyl alcohol as a 0.9% solution. It is used mostly for diluting and dissolving drugs for IV injection and as a flush for intravascular catheters. It also has local anesthetic properties.
List 4 clinical applications for agitated saline
- right to left shunt
- left to right shunt (*negative contrast due to the pressure gradient - microbubbles won’t cross the shunt since the LA has higher pressure)
- PFO
- enhance Doppler signals of TR
- pulmonary ateriovenous malformation
*Arteriovenous malformations (AVMs) refer to arteries and veins with abnormal connections between them.
_______ is standard for the diagnosis of PFO
saline contrast
*Saline is a mixture of salt and water. A normal saline solution is called normal because its salt concentration is similar to tears, blood and other body fluids (0.9% saline). It is also called isotonic solution. A homemade saline solution can be used to: rinse the nasal passages (nasal irrigation)
note: saline contain small amount of alcohol to mitigate any pain
Supplies used for bubble study:
- 10cc syringes x 2
- 9.5 mL saline
- 0.5 mL room air
- 3-way stopcock
- IV access
The agitated saline bubbles go through your IV, right side of the heart and travel to and through the vessels within your lungs. Normally the lungs will filter out all of the saline bubbles or allow for very slow passage of the bubbles to the left side of the heart.
T or F ?
T
What is PAVM?
Pulmonary arteriovenous malformations (PAVM) are rare pulmonary vascular anomalies. Although most patients are asymptomatic, PAVMs can cause dyspnoea from right-to-left shunt. Because of paradoxical emboli, various central nervous system complications have been described including stroke and brain abscess.
If the patient has a PAVM, the agitated saline bubbles will appear in the ____ of the heart after ______ of the heart and the test would be considered positive for intrapulmonary (within the lung) shunting (blood moving through a vessel without a capillary be
left side
3-5 beats
Microbubble characteristics
size:
1.1 - 8.0 micrometer or (2-8 micrometer)
*note: size of RBCs are 6-8 micrometer
Microbubble characteristics
stability
3-10min depending on the rate of injection and equipment setting
Microbubble characteristics
composition (2 types)
- outer shell (lipid membrane)
- contained gas (high-density perfluorocarbon)
Microbubble characteristics
acoustic properties:
- Acoustic impedance mismatch between outer shell and contained gas should be sufficient to enhance the reflected signal
- Resonant frequency doubles from transmitted frequency but diminishes amplitude
Contrast media for left heart opacification and myocardial perfusion:
appropriate rate and concentration
- Bolus: 10L/kg within 30-60 seconds followed by 10 mL saline flush
- Diluted Bolus: contrast diluted with saline
- Continuous infusion: _1.3 mL of contrast added to 50 mL of preservative free salin_e at the rate of 4.0 mL/min
*Bolus: A single dose of a drug or other substance given over a short period of time. It is usually given by infusion or injection into a blood vessel. It may also be given by mouth.
Contrast media for left heart opacification and myocardial perfusion:
Continuous image acquisition at high intensity levels has a tendency to _______________
destroy contrast agent
Sequential or intermittent imaging is used to spare the contrast agent.
T or F?
T
Contrast imaging can be gated or triggered to the ECG to allow time between imaging for restitution of the contrast.
T or F?
T
Appropriate equipment settings should be maintained to avoid destroying the contrast enhancement. Use vendor supplied presets.
T or F ?
T
For normal 2-D imaging the MI is set at ______
0.9- 1.4
For contrast imaging the MI is at a lower setting between _________to avoid bursting of bubble for longevity of visualization.
0.4 and 0.6
Appropriate Equipment Settings:
TDR frequency with optimal ______ should be selected.
penetration
Appropriate Equipment Settings:
Harmonic imaging should be selected with appropriate dynamic range, receiver filter, transmit frequency spectrum.
T or F ?
T
Appropriate Equipment Settings:
Focal zone should be placed in the _______
far field
Appropriate Equipment Settings:
Gain should be minimized in _____ (use ____)
the near field
TGCs
Indications for Use of Microbubble contrast:
- Predominate use is for opacification of left ventricular cavity to enhance wall border detection
- Used when standard transthoracic 2-D imaging is non-diagnostic
- May be used to enhance a weak aortic stenosis jet or pulmonary vein flow (used less often)
Contraindications for Use of Microbubble contrast:
- Known or suspected right to left shunts
- Pulmonary hypertension
- Pregnant or nursing mothers
- Hypersensitivity to perflutren
*note: Perflutren is an ultrasound contrast agent that is used to improve the quality of an echocardiogram (ultrasound of the heart). Perflutren works by changing the way ultrasound waves travel within your heart. This helps the ultrasound portray a sharper image of your heart.
Perflutren is used to allow certain segments of the heart to be seen more clearly on an echocardiogram.
Currently, echocardiographic contrast agents are indicated for LV opacification and endocardial border definition in patients with technically suboptimal studies.
The two FDA approved agents in the United States are _____ (perflutren protein type A microsphere) and ______ (perflutren lipid microsphere).
Optison
Definity
_________ (sulfur hexafluoride lipid-type A microspheres) is an ultrasound contrast agent indicated for use: in echocardiography to opacify the left ventricular chamber and to improve the delineation of the myocardium
LUMASON
Color Doppler is typically ______ by contrast injection.
degraded
There are a variety of ways microbubbles interact with the ultrasound beam including direct reflection of the fundamental frequency and resonance with creation of harmonic frequencies.
The maximum reflected frequency is dependent on the ______ of the bubble. The amplitude of the reflected frequency ______ as the bubble diameter decreases.
diameter
decreases
There are a variety of ways microbubbles interact with the ultrasound beam including direct reflection of the fundamental frequency and resonance with creation of harmonic frequencies.
The maximum reflected frequency is dependent on the ______ of the bubble. The amplitude of the reflected frequency ______ as the bubble diameter decreases.
diameter
decreases
*Key considerations that have guided the design of UEAs are that they must be safe, able to transit the _________ and _________ microcirculation unimpeded, and sufficiently stable after intravenous injection to reach the left ventricular cavity and he myocardium to produce strong acoustic signals.
pulmonary
systemic
What are the applications of Contrast Echocardiography?
- Endocardial border definitions
- Myocardial perfusions
- Doppler signal enhancement
- Definition of cardiac mass
Informed consent should be obtained prior to contrast injection (see manufacturer warnings) & Patient should be monitored for reactions for 30 minutes post injection.
T or F ?
T
*You should never inject an ultrasound contrast agent into a PIC line.
T or F ?
T
*When performing a contrast echo with an ultrasound contrast agent, you should select a transducer with the highest frequency possible.
T
*List 4 applications for the use of ultrasound contrast agents.
- Endocardial border definitions
- Myocardial perfusions
- Doppler signal enhancement
- Definition of cardiac mass
*When performing a contrast echo with an ultrasound contrast agent, most manufacturers of ultrasound equipment recommend that the focal zone should be placed in the near field.
T or F ?
F
*focus should be placed in far field
*Agitated saline is utilized for right heart opacification in cases where the patient has experienced transient ischemic attack (TIA) or a cerebrovascular accident (CVA) to determine the source of embolus?
List 4 of the 5 clinical applications for agitated saline we discussed in class.
- Right to left shunts
- Left to right shunt (negative contrast)
- PFO (Saline contrast is the standard for this diagnosis)
- Enhance Doppler signals of tricuspid regurgitation
- Pulmonary arteriovenous malformations