cardiac us
TRANSCRIPT
Emergency Cardiac Ultrasound
Phillip D. Levy, MD, MPH, FACEPAssistant Professor of Emergency MedicineWayne State University, Detroit Receiving
Hospital
Introduction
• “Stethoscope of the future”• Rapid visualization of cardiac
structures and potential pathology• More sensitive and specific than
physical exam, ECG or CXR
Primary Indications
• Suspected pericardial effusion or tamponade
• Cardiac arrest– PEA– Asystole vs. fine ventricular fibrillation
• Acute hypotension• Thoraco-abdominal trauma
Secondary Indications
• Acute chest pain– Myocardial infarction– Pulmonary embolism– Aortic dissection
• Procedural guidance– Pericardiocentesis– Detection of transcutaneous pacer
capture – Placement of transvenous pacer
Primary Clinical Concerns
• Is there cardiac activity ?
• Is there an effusion ?
Anatomical Overview
• Right ventricle anterior, left posterior
• Lungs provide poor transit medium – Air = scatter– Use liver as acoustic window for
subxyphoid approach
• Images quality can be limited by bony thorax
From: Yale Center for Advanced Instructional Media, Yale University. 2000
Technique
• Probe selection important– Curved array: better contrast resolution– Phased array (sector): less rib shadowing
• Average frequency = 3.5 MHz– 2.5 MHz for larger patients– 5.0 MHz for smaller patients
• Decrease depth and dynamic range • Reverse screen for true cardiac
imaging
Normal Appearance
• Pericardium: uniform, brightly echogenic line
• Myocardium: bulky, heterogeneous, hyperechoic material
• Chambers: anechoic
Basic Image Planes
Subcostal
• Most useful overall• Standard view in FAST exam• Ideal for detection of effusion and
cardiac motion• Diagonal view of heart • Liver functions as acoustic window
Subcostal
• Probe marker to patient’s right
• Subxyphoid position• Shallow angle (~
15°)• Aimed at left
shoulder
From: Yale Center for Advanced Instructional Media, Yale University. 2000
Subcostal
Parasternal Views
• Probe placed in left parasternal region at 2nd to 4th intercostal space– Left lateral decubitus position improves
images• Long axis (right shoulder to left hip)• Short axis (left shoulder to right hip)• Enables differentiation between
pericardial and pleural effusions
From: Gray, H. Anatomy of the Human Body 20th ed. 2000
Short axis
Long axis
Parasternal Long Axis
• Clearly displays– Posterior wall of LV– Free wall of RV– Mitral and aortic
valves– Proximal ascending
aorta
• Probe marker faces left hip
From: Yale Center for Advanced Instructional Media, Yale University. 2000
Parasternal Long Axis
Parasternal Short Axis
• Cross-sectional view through ventricles
• Rotate probe 90° toward right hip
• Tilting probe cephalad to caudad allows imaging from aortic valve to apex
Parasternal Short Axis
From: Yale Center for Advanced Instructional Media, Yale University. 2000
From: Yale Center for Advanced Instructional Media, Yale University. 2000
From: Yale Center for Advanced Instructional Media, Yale University. 2000
Parasternal Short Axis
Apical Views
• Left lateral decubitus position• Probe at apex (4th or 5th intercostal
space) facing right shoulder• More difficult to obtain• Provides good images of chamber
dimensions
Apical 4-chamber
• Good for evaluation of– Wall motion – Masses or clots
• Probe marker toward right hip
From: Yale Center for Advanced Instructional Media, Yale University. 2000
Apical 4-chamber
Apical 2-chamber
• Less commonly used in ED setting
• Shows anterior and inferior walls simultaneously
• Rotate probe 90°– Marker faces
anterior and cephalad
From: Yale Center for Advanced Instructional Media, Yale University. 2000
Apical 2-chamber
Functional Assessment
• Observation of dynamic changes of cardiac cycle
• Estimation of ejection fraction• Evaluation of wall motion
abnormalities– Characterized as global or segmental– Hypokinesis: reduced movement– Akinesis: absent movement– Dyskinesia: paradoxical movement
Normal Cardiac Cycle
Cardiac Measurements
• Chamber diameter– Measured at right angle to long axis
in both systolic and diastolic phases– Provide some functional information– Most useful as indication of
ventricular strain
• Wall thickness– Determination of hypertrophy
Clinical Indications
Pericardial Effusion
• High degree of accuracy for EP’s 1
– Sensitivity 99.9%– Specificity 98.1 %
• Anechoic stripe between visceral and parietal pericardium– May be echogenic if malignant or
coagulated• Usually surrounds heart completely
– If anterior only, likely pericardial fat
1 Plummer D, et al. Abstract, SAEM Scientific Assembly 1995.
Pericardial Effusion
• Cardiac impairment dependent of rate of accumulation of fluid in pericardial space, not amount – Up to 50 cc may be physiologic; usually
not visible– Small collection < 1 cm thick– Large collections 1-2 cm thick
• Heart may swing freely with large effusions
Pericardial Effusion
Pericardial Fat
Pericardial Blood Clot
Tamponade
• Cardiac compromise from effusion• Beck’s triad seen in only 30 % 1 • Pulsus paridoxus late, non-specific• Ultrasound findings
– Systolic right atrial collapse– Diastolic right ventricular collapse– Equalization of ventricular pressures– Increased central venous pressure
1 Guberman BA, et al. Circulation 1981
Tamponade
• Respiratory variance in IVC can be used to estimate central venous pressure 1
IVC sizeResp change RA pressure< 1.5 cm Total collapse 0-5 cm/H201.5-2.5 > 50 % collapse 5-101.5-2.5 < 50 % collapse 11-15>2.5 < 50 % collapse 16-20>2.5 No change > 20
1 Ma, OJ and Mateer JR. Emergency Ultrasound, p 111. 2003
Effusion with Normal Dynamic Function
Tamponade with RV Collapse
Acute Hypotension
• Determination of etiology may allow rapid intervention
• Tamponade• Cardiogenic shock
– Global hypokinesis– Left ventricular distention (MI)– Right ventricular distention
• PE or RV infarct
Acute Hypotension
• Hypovolemic shock– Hyperdynamic cardiac activity– Small right chambers– Collapsed IVC
• Septic shock– Hyperdynamic activity
Cardiac Arrest Applications
• Can be used while CPR is in progress• Evaluate for cardiac activity• Treatment guidance for PEA
– Rule out tamponade– Dynamism of cardiac contraction
• Hyperdynamic may indicate hypovolemia• Hypodynamic may be ischemia or PE
• Assess capture by transthoracic pacemaker 1
1 Ettin D, et al. JEM 1999
Blunt Thoracic Trauma
• Pericardial effusion • Traumatic aortic rupture
– Not ideal diagnostic modality (CT or TEE)– Look for
• Hematoma• Intimal flaps• Changes in vessel contour
• Sternal or rib fractures– Associated with underlying cardiac injury
Blunt Thoracic Trauma
• Cardiac contusion– Majority (73%) have signs of trauma 1
– Rarely associated with long-term impairment 2
– Limited diagnostic value of formal echo 3
– Screening ED ultrasound sufficient to rule out severe underlying injury 4
• Assess for wall motion abnormalities and RV hypokinesis
1 Snow, et al. Surgery 19822 Sturaitis M, et al.. Arch Intern Med 19863 Maenza RL, et al. Am J Emerg Med 19964 Welch RD. Emerg Med Clin North Am 2001
Penetrating Thoracic Trauma
• Goal is early detection of pericardial effusion BEFORE clinical signs develop
• Hemopericardium is anechoic initially– Echogenicity develops as blood coagulates
• Imaging may be limited – Subcutaneous emphysema– Pneumopericadium– Mechanical ventilation
Penetrating Thoracic Trauma
• Study of utilization in 261 pts 1
– Sensitivity 100%, specificity 96.9%– PPV 81%, NPV 100%– Time to OR 12.1 +/- 5.9 min
• Comparison of outcomes 2
– 28 pts with ED cardiac ultrasound, 21 without
– Survival: 100% in echo, 57.1% in non-echo– Time to diagnosis
• 15 min echo, 42 min non-echo
1 Rozycki GS, et al. J Trauma 19992 Plummer D et al. Ann Emerg Med 1992
Myocardial Infarct
• Determined by appearance of wall motion abnormalities– Poor sensitivity 1,2
– Better specificity, but difficult to assess age of pathology 3,4
• ED cardiac ultrasound may be most useful in ruling out other potential diagnoses
1 Levitt MA, et al. Ann Emerg Med 1996
2 Muttreja M. Echocardiography 19993 Horowitz RS, et al. Circulation 19824 Sabia P, et al. Circulation 1991
Pulmonary Embolism
• Large PE may cause sonographically identifiable right heart strain
• Wide range in accuracy 1-4
– Sensitivity 50-93%– Specificity 81-98%
• Right heart strain: potential criteria for thrombolytic administration? 5
1 Kasper W, et al. Am Heart J 19862 Nazeryollas P, et al. Eur Heart J 19963 Perrier A, et al. Int J Cardiol 19984 Rudoni R, et al. J Emerg Med 20015 Konstantinides S, et al. NEJM 2002
PE - Sonographic Findings
• Right ventricular dilation– Parasternal long axis view– Normal diameter 21±1 mm– Abnormal > 25-30 mm
• Septal deviation to left ventricle– Apical 4-chamber view
• Tricuspid regurgitation• Right ventricle hypokinesis, with wall
thinning
Massive Pulmonary Embolism
From: Goldhaber, SZ. NEJM 2002
Resolution After Thrombolytics
From: Goldhaber, SZ. NEJM 2002
Aortic Dissection
• Difficult to detect by transthoracic echocardiogram– Best seen on parasternal long axis
view
• Appears as echogenic, mobile, linear flap within aorta lumen
• May visualize double lumen
Other Findings
• Atrial myxoma– Globular and echogenic, adherent to
wall• Mural thrombi
– Varying echogenicity• Valvular vegetations
– Echogenic with irregular appearance• Valvular dysfunction
– Best seen with color flow Doppler
Atrial Myxoma
Mural Thrombus
Bacterial Endocarditis
Procedural Applications
• Pericardiocentesis– Left parasternal approach or entry
into largest area of fluid collection adjacent to the chest wall
– Lower risk of cardiac or hepatic injury
• Transvenous pacing – Allows highly accurate placement of
pacing wire 1
1 Aguilera P, et al. Ann Emerg Med 2000
Pericardiocentesis
Cardiac Ultrasound Pitfalls
• Not optimizing gain, depth and dynamic range
• Settling for inferior images due to technical difficulty
• Improper probe positioning• Mistaking pericardial fat for effusion• Mistaking clotted blood for normal
anatomy
Case 1
• 77 yo female with hx of breast CA, in remission for 2 yrs, presents with gradually worsening SOB and CP
• BP 90/50 HR 100 RR 26 T 99 SpO2 82 %• Lungs with faint crackles, heart sounds
distant• Abd exam nl; ext 2 + edema; neuro nl
• Management ?
Case 2
• 22 yo old male, with stab wound to left chest, vital signs stable in field
• Loses consciousness of arrival in ED• BP 60/palp HR 130 RR 6 T 98 SpO2 80%• 2 cm stab wound over L 4th intercostal
space; no other injury• Shallow breaths, no audible heart sounds
• Management ?
Take Home Points
• Learn the skill but know your limitations !
• Be sure to observe dynamic function
• Tilt, rotate or angulate probe to obtain optimal images
• Use early, use often!