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Case 37
Discharge
 | Presenting complaint: III/VI systolic murmur ausculted by
referring DVM. |
| PE: HR=160. Grade V/VI systolic murmur heard bilaterally
but loudest at right basilar region (palpable thrill felt
here). Grade I/VI diastolic murmur heard best at the left apex.
Femoral pulses strong and synchronous. |
| Thoracic radiographs: The lateral projection suggests left
heart enlargement as evidenced by the tall cardiac silhouette. A
post-stenotic dilatation is also appreciated in the aortic region on the
lateral projection. Pulmonary parenchyma and vasculature are unremarkable.
|
| ECG: HR=180. Occasional VPCs originating from the left
ventricle. Couplets are present with an instantaneous rate ~300 bpm. ST
segment elevation suggestive of regional hypoxia/ischemia
for which there was evidence on the echocardiogram. |
| ECHO: IVSd=1.7 cm, LVIDd=2.6 cm,
LVPWd=1.1 cm, IVSs=2.0 cm, LVIDs=1.2 cm, LVPWs=1.6
cm, Ao root diameter=1.6 cm, LA dimension=1.9 cm,
LA/Aorta=1.2, FS=54%.
Velocity across the aortic valve = 4.6 m/s; aortic
max PG = 86 mmHg. The primary
diagnosis is severe subaortic stenosis (SAS);
a turbulent jet begins at the subvalvular region,
mild aortic insufficiencyis present and
there is severe left ventricular hypertrophy with
hyperechoic papillary muscles and subendocardium.There is
slight mitral regurgitation. No left atrial
enlargement is noted. |
| Conclusion: ECG, thoracic
radiographs and the echocardiogram
are consistent with severe subaortic stenosis. Physical exam findings
(right-sided murmur, strong femoral pulses) are
not the most common for SAS but
are seen with severe SAS and consistent with the diagnosis.
The presence of severe SAS with
VPCs indicates increased risk of sudden
death. Prognosis is poor given severity of stenosis in 9 week old patient.
It is likely that the pressure gradient across the aortic valve will
continue to increase until Howie is mature. Balloon valvuloplasty is
recommended only as a salvage procedure due to increased risk of mitral
regurgitation, worsening left atrial enlargement, congestive heart failure,
and sudden death. Atenolol may decrease the risk
of a malignant ventricular arrhythmia
leading to sudden death. Patient may
exhibit clinical signs (syncope, sudden death) within months to a few years.
Rx: Atenolol 12.5 mg PO BID. This dose will need to be
increased as Howie grows. Recommend recheck at
6 months and 1 year of age unless clinical signs
worsen. Prophylactic antibiotics are recommended
in bacteremic times in an attempt to decrease Howie's increased risk of
aortic vegetative endocarditis. |
| Thank you for bringing Howie to the VMTH. He is such a
cutie! |
| Howie presented to the VMTH on 11/3/04 because your
referring veterinarian detected a murmur on physical exam. |
| On our physical exam, we detected a grade V/VI systolic
murmur which was heard loudest over the right side but was also loud on the
left side. We took chest x-rays which showed enlargement of the left side of
his heart and a narrowed region below the aortic valve. An ultrasound of his heart showed that
he has severe subaortic stenosis (SAS). SAS is a disease where the lumen of
the aorta is very small, restricting the blood flow from the left side of
the heart into the body, and causing a loud
heart murmur. A secondary
effect of SAS,
which is present in Howie,
is leakage from his aorta back into his left
heart (called aortic insufficiency, which is mild).
He also has mild leakage from his left ventricle into
his left atrium (called mitral insufficiency). |
| We also did an ECG which showed some irregular beats,
which also means his condition
is more severe and may be an indication that he is
at increased risk of his heart
stopping suddenly (sudden
death). |
| SAS is a progressive disease in
early life, and we expect the changes
in his heart to worsen up until he is around 6 months of
age. Possible complications of SAS include collapsing, sudden death,
and infection of his aortic valve. There is no surgical treatment for
SAS. Medical treatment is aimed at trying to prevent
sudden death from an abnormal heart rhythm. Due to his increased risk
of aortic valve infection, Howie should receive antibiotics anytime he has
the possibility of getting bacteria in his blood stream (e.g., dental procedure)
|
| The long-term prognosis
without treatment is poor and with medical treatment is
unknown but hopefully better. |
| Please give the following medication:
atenolol 12.5 mg (1/2 tablet) by
mouth twice daily. This medication is used to decrease
the number and severity of abnormal beats and
so may
help prevent sudden death. |
| We would like to see Howie back in 6 months and at 1 year
of age to recheck his heart. In the meantime,
watch him closely for signs of collapse, exercise intolerance,
or any other abnormality; and call us if any of
these occur. |
| Thanks again for letting us see Howie.
|
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