Case Studies In Small Animal

Cardiovascular Medicine

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Case 34

Presenting Complaints

bulletOne-year Recheck

Pertinent History

bulletChristopher presents to the Cardiology Service for a recheck of his pacemaker placed approximately one year ago. Christopher was initially seen by the Neurology Service for episodes of collapse. A Cardiology consult revealed a conduction abnormality with periods of high grade second degree AV block and third degree AV block. Christopher was eventually treated with a pacemaker (implanted surgically) since his syncopal episodes kept increasing in frequency. Christopher has been doing very well with his pacemaker and has had no episodes of collapse since it was placed.
bulletChristopher was also diagnosed with supraventricular tachycardia in shortly after pacemaker implantation. It was unclear if Christopher's own rhythm was a normal sinus or a slower supraventricular tachycardia. Christopher was started on diltiazem to control the SVT. An interventricular septal aneurysm was also identified in previously and was suspected to be the cause of his heart murmur.
bulletThe owner is a little concerned because Christopher has been mildly lethargic lately. His appetite is excellent, and he has had no V/D/C/S.
bulletChristopher's diet consists of Friskies wet and dry food. Christopher is current receiving 7.5mg of Diltiazem PO TID for supraventricular tachycardia.

Physical Examination

bulletGen: BARH, P:140, R: purr, T=101.1 F.
bulletInt: Full hair coat with mild scaling on dorsum.
bulletEENT: Eyes: Clear sclera, cornea, conjunctiva, and anterior chamber OU; Ears: Moderate brown clumpy discharge AS, mild brown discharge AD; Nose: no discharge; Throat: mild calculus and gingivitis.
bulletMS: BCS 6/9, no gait abnormalities.
bulletCV: III/VI left parasternal systolic murmur, irregular rhythm, CRT=2 sec, mm=pink and moist, strong but irregular femoral pulses.
bulletResp: Clear breath sounds in all fields.
bulletGI: Smooth bowel loops, no masses or organomegaly.
bulletGU: Smooth 3-4cm kidneys, smooth 4-5cm bladder.
bulletNS: Appropriate mentation, full exam not performed.
bulletLN: Mandibular, prescapular, and popliteal all <1cm.


bulletThird degree AV block
bulletEpicardial pacemaker
bulletMyocardial failure
bulletSupraventricular tachycardia (controlled)

Clinical Diagnoses

bulletThird degree AV block
bulletEpicardial pacemaker
bulletMyocardial failure
bulletMild aortic insufficiency with an interventricular septal aneurysm
bulletHistorical supraventricular tachycardia (controlled)
bulletPremature ventricular complexes


bulletECG: Average HR ~130, the pacemaker is pacing appropriately after periods of second and third degree AV block. Occasional VPCs originating from the left ventricle are noted.
bulletEcho: IVSd 4 mm, LVIDd 22 mm, LVFWd 4 mm, IVSs 7 mm, LVIDs 13 mm, LVFWs 7 mm, Ao 11 mm, LA 16 mm, LA/Ao=1.4, FS 38%.
bulletTrivial diastolic mitral regurgitation and mild aortic insufficiency are noted as is the previously described septal aneurysm.
bulletConclusion: Christopher still has myocardial failure that appears static since his last visit. The septal aneurysm is not clinically significant but may be the cause of the murmur. It is also possible that the aneurysm is interfering with conduction and thereby contributing to his arrhythmia. The pacemaker appears to be adequately pacing. Christopher's LVIDd (EDD) has increased from his last visit. It is unclear why his EDD has increased. Christopher is doing very well clinically, and he will return for a recheck in 6 months.

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