March 2015

P 1- Case Study: Some Fast Friends Need to Slow Down

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P 2- Case Study (continued)

- Did You Know?

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P 3- Continuing Education: Arizona Veterinary Day With The Specialists

- Team Member Highlight: Dr. Whit Church

- Technician Tip: Diabetes Testing

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P 4- Testimonial: Buddy

dvmspecialists.com

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HistoryOrion (now a four-year-old, neutered, male Labrador retriever) was diagnosed with a supraventricular tachycardia secondary to suspected dilated cardiomyopathy one year ago while traveling outside the state. He originally presented with paroxysmal narrow complex tachycardia and a heart rate of 375bpm. The original echocardiogram showed significant systolic dysfunction of the left and right ventricles and dilation of all four chambers. There was also mild mitral and tricuspid regurgitation with no significant valvular dysplasia or valve thickening. His heart rhythm and clinical symptoms stabilized for about nine months on a combination of diltiazem, digoxin, and enalapril. But several episodes of syncope have been seen in the last three months, and two episodes occurred in the week prior to the appointment with our cardiology service.

DiagnosticsOrion had a mostly normal cardiac examination, except for one brief episode of tachycardia estimated at over 240bpm. There was no cardiac murmur. Femoral pulses, lung sounds, mucus membranes, and jugular veins were all normal.

An ECG was performed, revealing a respiratory sinus arrhythmia with evidence for pre-excitation. There was a short P-R interval and a delta wave appeared intermittently in chest lead V1 (Table 2). The QRS complexes were narrow, with deep Q waves in leads I and II (Table 1). Deep S waves were observed in lead III (Table 1). Significant notching of the QRS was seen in chest leads V2 and V3. There were also several episodes of sustained, but paroxysmal supraventricular tachycardia, with rates as high as 375bpm (Table 1).

The echocardiogram revealed all four chambers to be mildly dilated or at the high end of normal size, and the M-mode and two-dimensional measurements supported the subjective assessment. The systolic function appeared reduced, particularly in the anterior to posterior direction, with a fractional shortening percentage in the 2D short axis anterior to posterior direction of 20 percent.

Cardiology Case Study | Some Fast Friends Need to Slow Down.

Table 1 Table 2

(continued on page 2)

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Whit Church, DVMDiplomate ACVIM (Cardiology)

Cardiology Case Study | Some Fast Friends Need to Slow Down (continued).

However, the ejection fraction from the left apical four-chamber view was 53 percent when calculated using the modified Simpson’s method. Compared to the previous echocardiogram measurements, which were taken one year ago, the left ventricular end diastolic diameter had reduced by 5mm, and the left atrial diameter had reduced by 3mm. There was no detectable mitral regurgitation, no tricuspid regurgitation, and the tricuspid valve appeared normal. Aortic and pulmonic flow velocities were normal. The right ventricular acceleration time and AT/ET ratio were consistent with normal pulmonary artery pressures. No pericardial effusion was present.

DiagnosisThe previous echocardiogram measurements are consistent with dilated cardiomyopathy with a significantly reduced left ventricular fractional shortening of 16 percent, as well as significantly increased left ventricular and left atrial diameter. However, the improvement in the echocardiogram parameters suggests a diagnosis of a tachycardia-induced cardiomyopathy rather than a true idiopathic dilated cardiomyopathy.

TreatmentI recommended switching from diltiazem and digoxin, to mexiletine and carvedilol, to discourage conduction through the accessory pathway and delay conduction through the AV node. The risk of spontaneous heart failure is currently low, and the renin, angiotensin II, and aldosterone are unlikely to become elevated. This makes enalapril of limited benefit, so I would consider discontinuing this medication. Ablation of the Kent bundle is available, but with Orion’s response to the medication, it would likely be unnecessary.

PrognosisThis form of cardiomyopathy is caused by persistently elevated heart rates and can be reversible if the rhythm, or at least the heart rate, is well controlled. The evidence for pre-excitation is strong on the ECG. This and the breed are consistent with an accessory pathway re-entrant tachycardia with a rate-induced cardiomyopathy. An accessory pathway (also called a bypass tract, or Kent bundle) is an electrical connection between the atrium and ventricle other than the AV node.

Note: One form of this condition in humans, is called Wolff Parkinson White Syndrome – a congenital condition that often manifests in patients between the ages of one and three years old. It has also been reported in dogs and is most often seen in Labrador retrievers. In this case, the disease has been stable for months as evidenced by the lack of syncope and by improvement in the systolic function of the ventricles and reduction in heart size. Given the recurrence of symptoms and the persistence of some echocardiographic abnormalities on the echocardiogram, changes in the antiarrhythmic therapy were indicated.

DID YOU KNOW... DVMS OFFERS TELERADIOLOGY SERVICES.

First time users: call 888.669.8090 or email support@dvminsight.net to sign up for this service

Digital images may be submitted online at dvmspecialists.com (Click on “For Veterinarians” tab)

All images are interpreted by our radiologist, Vicki Heffelman, DVM, DACVR

Analog film radiographs are also accepted by mail

Detailed reports are sent within 24 hours

For more information, please call 480.635.1110 x6 and we’ll be glad to show you how to submit images through our website.

SAVE THE DATE

SIX UNIQUE LECTURES BY VETERINARIANS FROM ARIZONA VETERINARY SPECIALISTS

Diligent testing and monitoring is crucial to the proper management of diabetes mellitus. There are two basic ways this can be accomplished.

The first is to do a blood glucose curve. This is done by testing the blood glucose levels every two hours for a 12 to 24 hour period. This test is used to evaluate the glucose levels for the period being tested. It can be performed in the hospital, but requires that the pet stays at the hospital for the entire testing period, which often is very stressful for them. Therefore, it is best used for patients whose owners are willing and able to do the glucose tests at home, as it offers a more accurate evaluation of the pet’s real daily circumstances.

The second option is to run a blood test called serum fructosamine. This test measures the blood’s percentage of fructosamine, which is the product of a reaction between glucose and albumin. This test is used to evaluate the average amount of glucose in blood over a period of two to three weeks, and is best used for patients who become overly stressed staying in the hospital and/or for patients whose owners are not able to do glucose curves at home.

The best testing method for each individual patient can be determined by working closely with the patient and their owner(s). Either method can be used to monitor patients with diabetes mellitus so that the condition can be managed effectively.

TECHNICIAN TIP

DIABETES TESTINGDANETTE ALLEY, CVT

Join us for our upcoming CE Event WHEN: JUNE 13, 2015 12:30 pm – 8:00 pm (Registration begins at 12:00 pm)

WHERE: Sheraton Hotel Airport Phoenix/Tempe 1600 S. 52nd Street • Tempe

Dr. Church earned his veterinary degree from Oregon State University in 2002. After graduation he completed a one-year internship at Cornell University followed by a cardiology residency and Master of Science degree at the University of Illinois. He finished the last year of his residency at the University of Pennsylvania and moved to Arizona with his family in 2006 to provide specialized cardiology services.

His special areas of interest include pericardial diseases, echocardiography, and interventional cardiovascular procedures.  He lectures all over the country at both national and local continuing education conferences. Dr. Church is also a founding member of the Cardiac Education Group.

TEAM MEMBERHIGHLIGHT

WHIT CHURCH, DVM, DACVIM (CARDIOLOGY)

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Dearest Dr. Church, Dr. Riensche, Dina, and Katie:

Thank you for the very touching card signed by all. Because of your professional and compassionate care, and his determination, we were able to enjoy Buddy’s love and companionship for as long as we did. He was the joy of our life. We will miss him dearly, but recognized that it was time for him to move on in peace and tranquility.

Your support throughout this ordeal made the situation more bearable. After all… now he’s with Joluy and Chanel in doggie heaven.

Again, thank you so very much and God bless.

— Denise and Troy Vickers

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