Case Studies In Small Animal

Cardiovascular Medicine

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Case 7

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Two Month Reexamination

Cindy was reexamined two months after the balloon valvuloplasty (6 months of age). At that time, she was clinically normal to the owner who noticed no difference in activity between Cindy and her other toy poodle. She had doubled her weight from 2.2 to 4.5 kg. Whereas her packed cell volume was 68% at the time of the first examination, this time it was down to 51%. An arterial blood gas revealed an arterial oxygen tension of 62 mm Hg. It had been 55 mm Hg on 100% oxygen previously and was almost assuredly somewhere below 40 mm Hg on room air at the time of the first examination. Her pressure gradient across her pulmonic valve region was 64 mm Hg. Based on these data, the owner was given a good prognosis and Cindy was sent home. The summary from her record is provided below.

Thoracic radiographs: Radiographs were taken today to further evaluate Cindy's cough. No tracheal collapse is noted, no abnormal lung patterns noted, and no significant changes in the size or shape of her heart when compared to previous radiographs.

ECG: sinus rhythm, tall P waves at approximately .6mV suggestive of enlarged RA, right axis shift (-140), right bundle branch block (QRS complex approximately 90msec in duration).

Echocardiogram: Moderate pulmonic stenosis with a pressure gradient of 64 mmHg (velocity 4 m/s). Both membranes of the foramen ovale were again visualized. The right ventricle is slightly less hyperechoic than three months ago, although this is difficult to discern definitively since the entire heart has grown with the dog and it is still quite bright.
Mild tricuspid regurgitation. RVFW(d)=0.8cm, IVS(d)=0.8cm, LVEDD=1.9cm,
LVESD=1.2cm, FS=38%, LVFW(d)=0.4cm, Ao:LA normal.

Saline contrast echocardiography: mild right to left shunting at the atrial level.

PCV: 51% This is less than in April, when it was 68%, indicating that she is probably shunting less blood from right to left via her patent foramen ovale resulting in less hypoxemia as a stimulus for red cell production.

Arterial blood gases: PaO2=63mmHg, PaCO2=36mmHg on room air. She is still not oxygenating well, which is further indication that she continues to shunt blood from right to left however the degree of hypoxemia is improved from the 40 mmHg pre-op and is more compatible with a normal lifestyle.

Conclusion: The reduction in pulmonic stenosis gradient obtained via balloon valvuloplasty has been effective at improving Cindy's oxygenation and decreasing her right to left shunting. Although a shunt still exists and she has evidence of moderate desaturation, her clinical signs have resolved and the owner reports normalcy. Her PS gradient is slightly higher than that obtained post-op - this more likely is reflective of increased flow through the valve rather than recurring stenosis. Should her gradient increase in the future, however a second BD could be performed. We recommend a recheck in one year.

 

 

Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.