Case Studies In Small Animal

Cardiovascular Medicine

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Case 23


Clinical Diagnosis

bulletSevere tricuspid valve dysplasia


bullet Radiographs: Severe right heart enlargement (right atrial enlargement). 
ECG: Heart rate irregular and ranged from 64-210 bpm, with a mean of 130 bpm. Coarse atrial fibrillation. MEA +70 There are splintered QRS complexes (RSr') characteristic of tricuspid valve dysplasia. Prominent R waves on V1 right chest lead, deep S waves in V4 left chest lead suggesting right ventricular hypertrophy.
bullet Echocardiogram: Due to the severe derangement in the cardiac size, M-mode measurements of the left ventricle were not obtained. There was severe right atrial enlargement. The tricuspid valve is severely dysplastic, with abnormal papillary muscle attachments to the tricuspid valve cusps. The abnormal papillary muscles are severely tethering the tricuspid valves, causing a large gap in valvular coaptation during systole. There is severe tricuspid regurgitation of normal velocity 2.8 m/s. 
bullet Conclusion: Max has severe tricuspid valve dysplasia and early right heart failure. This is a heritable, congenital disease that is most commonly seen in Labrador retrievers. therapy is aimed at reducing heart failure, and only definitive treatment is a tricuspid valve replacement. There is such severe
right atrial enlargement that even valve replacement might not be very effective. The prognosis is guarded. 

Discharge Summary

bulletMax was seen at the VMTH to evaluate an arrhythmia and cardiomegaly found by the referring DVM. Max has no clinical signs except a dry nonproductive cough that started about 2 weeks ago. On physical exam a V/VI systolic murmur was noted over the right side of his chest and the heart rhythm was very erratic. He has weak femoral pulses with pulse deficits. The jugular veins are distended. He also had moderate hepatomegaly with no ascites. Radiographs revealed severe right atrial enlargement. The ECG showed evidence of atrial fibrillation and were suggestive of tricuspid valve dysplasia (splintered QRS complexes). The echocardiogram revealed tricuspid valve dysplasia with severe tricuspid regurgitation and right atrial enlargement. Max was diagnosed with right heart failure. His prognosis is guarded. Therapy was aimed at ameliorating the signs of right heart failure and included the following: Lasix 50mg orally BID, digoxin 0.25mg orally BID, lisinopril 20mg orally SID. Max will return in 7-10 days to check blood levels of digoxin and then again in 6 months for a recheck. 

One Week Later

Pertinent History

bullet Max was diagnosed with severe tricuspid valve dysplasia on 11/3/99. He had a V/VI systolic murmur over the right heart base with an erratic rhythm that was diagnosed as Atrial Fibrillation. Echo showed severe right atrial enlargement , with severely dysplastic tricuspid valve and abnormal papillary muscle attachment. At that time he was placed on Lasix 50 mg orally BID, digoxin 0.25 mg BID, lisinopril 20 mg PO BID. Today Max presents for 3-4 days of anorexia and lethargy. 

Physical Examination

bullet Gen: BAR marginal dehydration 
bullet Integ : Good coat, salivary staining on hind paws. 
bullet MS: 4/9 
bullet CV: IV/VI right sided murmur loudest at the apex, irregularly irregular rhythm (atrial fibrillation), MM= pink, CRT< 2 sec, pulses of variable intensities but strong 
bullet RR= 78 (but panting), Clear lung fields.
bulletLymph nodes: WNL
bullet GI: Hepatomegaly, gut loops smooth.


bulletTricuspid Dysplasia
bulletAtrial Fibrillation

Discharge Summary

bulletMax was diagnosed with severe tricuspid dysplasia and atrial fibrillation one week ago. He was sent home on digoxin 0.25 mg BID, lisinopril 20 mg SID, and Lasix 50 mg BID. Today he presents having been anorectic since the digoxin was started. We drew blood for a kidney panel and digoxin level and sent him home with instructions to discontinue the digoxin until further notice. Digoxin toxicity often results in GI side effects such as anorexia, vomiting and diarrhea. Results of digoxin levels were 2.5 ng/ml - above our therapeutic range of 0.5 - 2.0 ng/ml. The owner was instructed to stop giving digoxin for 2 days; then give 0.125 mg PO BID.
bulletRenal profile revealed normal BUN and creatinine; slight decrease in electrolytes most likely due to diuretic and anorexia.

Five months later

bulletMax is still doing well. He remains on the same medications he was on previously. He is active but tires easily when exercised and he remains a finicky eater but otherwise is a happy boy.:)

Two years later

bulletIn a telephone conversation with Max's owner, he says that Max is still doing wonderfully. He is currently on 50 mg Lasix BID, 15 mg enalapril BID, and digoxin. Max is retired from the narcotics squad and living the good life. The only thing that Max's owner notices is that after a two mile walk, Max starts slowing down a bit. Not bad for a big-hearted dog!

Three years later

bulletMax was euthanized due to severe right heart failure. He became emaciated, weak, and wouldn't eat. Max's owners currently have a new 5-month-old Labrador puppy. Although no dog can ever replace Max, the new puppy helps fill some of the void.

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