Congenital Cardiac Disease Echocardiographic Exam
The Echocardiographic Exam
The echocardiographic examination should be conducted in a systematic matter.
The examiner must be able to perform two-dimensional, pulsed-wave Doppler,
and continuous wave Doppler examinations of the heart. The availability
of color Doppler is valuable but not essential for most examinations. The
echocardiographic examination should be performed and interpreted by individuals
with advanced training in cardiac diagnosis.
Board certification by the American College of Veterinary Internal Medicine,
Specialty of Cardiology is considered by the American College of Veterinary
Medical Association as the benchmark of clinical proficiency for veterinarians
in clinical cardiology, and examination by a Diplomate of this Specialty
Board is recommended. Other veterinarians may be able to perform these examinations
provided they have appropriate equipment and have received advanced training
in echocardiography.
Imaging
The pericardial space, both atria, both ventricles, the great vessels, and
the four cardiac valves should be imaged using long axis, short axis, apical,
and angled image planes as necessary to perform a complete examination of
the heart. Nomenclature should follow that recommended by the American College
of Veterinary Internal Medicine Specialty of Cardiology. An anatomic diagnosis
may be possible based on two-dimensional imaging; however, the origin of
cardiac murmurs should also be evaluated using Doppler methods.
Doppler
Doppler examination of all cardiac valves should be performed and recorded.
Abnormal flow should be quantified using pulsed wave or continuous wave
Doppler techniques. Values obtained should be compared to reference values.
The depressant effects of any tranquilizers or sedative must be considered
when measuring peak flow velocities. Color Doppler echocardiography should
be employed if available to assess normal and abnormal blood flow patterns.
Identification of abnormal flow across the cardiac septa or shunts at the
level of the great vessels is best done by a combination of color and pulsed
wave Doppler techniques. Typical echocardiographic features of common congenital heart defects are indicated in table one.
Assessment of flow patterns and velocities
Special attention should be directed to the assessment of flow patterns
and velocities in the left ventricular outlet and descending aorta. Optimal
alignment with blood flow should be sought for accurate velocities to be
reported. This may require the use of sub-xiphoid (subcostal) transducer positions as well as left apical (caudal parasternal) transducer placements.
In addition to measurement of peak velocity using pulsed or color wave Doppler,
the pulsed wave sample volume should be gradually advanced from the subaortic
area into the ascending aorta in order to identify sudden accelerations
in flow velocity, turbulence, or aortic regurgitation.
Videotape
Echocardiographic studies should be reported on videotape for subsequent
analysis and a written record of abnormal findings should be entered into
the medical record.
Echocardiographic findings
| Congenital
Defect |
Typical
Auscultatory Features |
Diagnostic
Echocardiographic and Doppler Echocardiographic Features |
| Patent ductus arteriosus |
Continuous heart murmur with maximal intensity over the
left cranial dorsal cardiac base |
Continuous retrograde flow from the patent ductus arteriosus
into the pulmonary artery |
| Ventricular septal defect |
Systolic murmur with maximal intensity over the right ventral
precordium; less often maximal intensity is over the pulmonic valve
area and pulmonary artery | The septal defect can often be imaged in multiple imaging
planes. Abnormal, generally high velocity, systolic flow across the
septal defect is evident. |
| Atrial septal defect |
Systolic murmur with maximal intensity over the pulmonic
valve area and pulmonary artery. The second heart sound may be widely
split | The septal defect can generally be imaged in multiple imaging
planes. Abnormal blood flow may be identified across the septal defect
into the right atrium. |
| Pulmonic stenosis |
Systolic murmur with maximal intensity over the pulmonic
valve area and pulmonary artery |
Abnormal pulmonary valve and /or subvalvular anatomy.
Sudden acceleration of blood flow in the right ventricular outlet
with turbulent, high velocity systolic flow across the pulmonary valve
and into the main pulmonary artery. |
| Valvular and subvalvular aortic stenosis |
Systolic murmur with maximal intensity over the subaortic
or aortic valve area and radiating into the ascending aorta. The murmur
may also be prominent over the right cranial thorax. |
Abnormal subvalvular or aortic valvular anatomy may
be evident. Sudden acceleration of blood flow into the left ventricular
outflow tract with turbulent, high velocity systolic flow across the
aortic valve and into the ascending aorta. Concurrent aortic regurgitation
is usually present. |
| Mitral valve dysplasia |
Systolic murmur with maximal intensity over the left apex
and mitral area | Abnormal anatomy of the mitral valve apparatus. High
velocity retrograde systolic flow across the mitral valve into the
left atrium. Concurrent mitral valve stenosis may be present. |
| Tricuspid valve dysplasia |
Systolic murmur with maximal intensity over the tricuspid
valve area |
Abnormal anatomy of the tricuspid valve apparatus. High
velocity retrograde systolic flow across the tricuspid valve into
the right atrium. Concurrent tricuspid valve stenosis may be present. |
| Right to left cardiac shunt |
Variable—a systolic murmur at the left base is often
detected; cyanosis is an important clinical sign |
Abnormal anatomy related to the cardiac malformations
examples include: tetralogy of Fallot, patent ductus arteriosus with
pulmonary hypertension, pulmonary or tricuspid valves stenosis with
atrial septal defect. Right to left shunting may be documented by
Doppler techniques and/or by contrast echocardiography. |
