INTERACTIVE CASE STUDIES

 
 

RileyCase Background

 Name Riley
 Age  12 years
 Sex  Male, castrated
 Breed  Shih Tzu
 Weight  6 kg
 Reason for visit Presented two days ago to your colleague for a complaint of respiratory difficulty for one week. Now the owner, Mr. Brown, has brought him back to you because he has noticed a distended abdomen and is concerned because Riley is not eating well. During the initial visit a murmur was identified and Riley was tentatively diagnosed with CHF and started on Furosemide, enalapril and spironolactone.
 Medications Heartworm prevention: Heartgard® plus and Frontline®

Please review Riley's clinical history.

 
Attitude/Demeanor Bright and alert
Coughing None reported
Respirations Increased inspiratory effort with shallow breathing
Exercise Tolerance Has generally been slowing, but is now more reluctant to exercise
Sleep Patterns Sleeping well, but he prefers to sleep on his belly and not on his side
Weight Change (loss or gain) Significant abdominal distension
Appetite Not eating as well for the last 2 days
Usual Diet Science Diet® maintenance dry
Vomiting None reported
Diarrhea None reported
Syncope None reported
Change in urinary habits Increase in urinating since meds started yesterday
Change in drinking habits Increase in drinking since meds started yesterday
Other signs or symptoms None reported
 

Please review the results of Riley's physical exam.

Body Condition Good, BCS 6/9
Attitude Alert, somewhat anxious
Mobility | Gait Normal gait on inspection
Posture Standing or sitting
Hydration Normal
Body Temperature 100.3 F
Arterial pulse - rate, regularity, intensity 132 beats/min, occasional premature beat, pulses fair
Respiratory Rate & Effort 40, mild inspiratory effort, breathing shallow
Mucous Membranes - Color & CRT Pink, <2 seconds
Jugular Venous Pulse & Pressure Jugular distension, no pulsation
Abdominal Palpatation Severe abdominal distension, fluid wave suspected, internal organs difficult to palpate
Lymph Nodes Normal
Oral Cavity Mild dental calculus
Other abnormalities None
 

Let's auscult Riley's heart & lungs.

The following recording is taken when the stethoscope is placed over the left apex. Similar sounds are heard when the stethoscope is placed over the right mid-heart.

Listen to Riley's heart sounds.

Auscultation identifies a loud (Grade 4/6) holosystolic murmur.
Incorrect. Given the loudness of the murmur and the ability to hear it over both sides of the chest the murmur cannot be considered soft (Grade 1/6 or 2/6).
Auscultation identifies a loud (Grade 4/6) holosystolic murmur.
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 Direct HR  140
 Heart Rhythm  Regular with occasional premature beats
 Intensity of heart sounds  Heart sounds audible, but reduced
 Extra sounds - clicks or gallops  None
 Precordial palpation  No thrill detected

The following are potential diagnosis for you to consider at this time. Based on the history and the physical examination, please indicate the likelihood of each as: 1. High (could explain most or all of the signs) 2. Possible (less likely to explain most of the signs) 3 Unlikely

Stage C CVD

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Stage C DCM

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Right sided CHF secondary to HW disease

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Pericardial effusion causing ascites (tamponade)

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The CEG considers the following differential diagnosis as most likely:

CHF secondary to chronic valvular disease (CVD) is the most likely underlying etiology of the clinical signs because Riley is a small (<20Kg) older dog with a loud heart murmur characteristic of mitral regurgitation (MR). Dilated cardiomyopathy (DCM) cannot be ruled out but would be very unlikely in a Shih Tzu. CHF secondary to heartworm (HW) disease should be considered in endemic areas especially if dogs are not on preventative. Pericardial effusion with tamponade is less likely because his heart sounds (murmur) are loud.

BLOOD PRESSURE

Non-invasive blood pressure

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CLINICAL LABORATORY

CBC with platelet count

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Coagulation profile

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Serum biochemical profile (includes electrolytes)

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Urinalysis

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Serum thyroxine (T4)

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Heartworm antigen test

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Heartworm antibody test

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Heartworm microfilaria test

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NT-proBNP

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Cardiac troponin-I

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Blood culture

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Thoracocentesis or abdominocentesis for diagnosis or therapy

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DIAGNOSTIC IMAGING (some may require a referral)

Thoracic radiographs

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Abdominal radiographs

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Echocardiogram Doppler studies

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Abdominal ultrasound

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ELECTRODIAGNOSTICS (some may require a referral)

ECG rhythm strip or 6 lead ECG

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Ambulatory ECG - Holter ECG or event monitor

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  • You considered the following to be higher priority
    • You considered the following to be lower priority
      • You considered the following to be not indicated

        The CEG considers the following diagnostic tests as the highest priority: 

        Thoracic radiographs must be considered as the most important diagnostic test in a patient with respiratory signs suspected of having congestive heart failure.

        An echocardiogram should be performed to confirm that there is enough underlying heart disease present to make the clinical signs likely to be attributable to heart failure. In addition, an echocardiogram is the definitive diagnostic test to document the presence of pericardial effusion, pulmonary hypertension and severe heartworm disease. Obtaining a serum chemistry is also important in this case, as the owner complained that Riley's appetite has suffered after starting the cardiac therapy. Impairment of renal function and resulting azotemia is an important cause of decreased appetite in patients receiving therapy for CHF. Similarly, a blood pressure evaluation is important to rule out systemic hypertension and to identify adverse effects of current therapy. This is especially important if additional therapy is contemplated. An ECG should be obtained in any patient where an arrhythmia is identified/suspected (Riley had premature beats detected on auscultation). NT-proBNP is less useful if significant heart disease has been identified by echo; however this may be a very useful test if an echocardiogram cannot be obtained. A heartworm test can also be considered in a patient presented with signs of heart disease and right-sided heart failure; while still appropriate in this case, it may be less important given the rest of the case history.

        Evaluation of the abdomen (e.g. use of ultrasound, radiographs and/or fluid analysis) can also be considered, but would be most important if significant heart disease is not identified. In some cases, abdominal evaluation may be more important, especially if an acute abdomen (hemoabdomen, peritonitis, etc.) is suspected based on clinical findings. Similarly, a complete blood count can be considered a higher priority if infection/bleeding is a concern.

        Systolic Blood Pressure: 110mmHg
        Diastolic Blood Pressure: Not available for this case
        Mean Blood Pressure: Not available for this case
        Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provides the veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of clinically important animal diseases. In 2007, ACVIM published guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats in the the Journal of Veterinary Internal Medicine.
        Click here to view and download a PDF of the ACVIM Consensus Statement, Guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats.  

        Please review Riley's thoracic radiographs

        Click here for the ventral dorsal view
        Click here for the right lateral view
        Click here to see the CEG's recommendation on Evaluating Heart Size on Radiographs

        Is there evidence of pleural effusion or pulmonary edema to explain the respiratory signs?

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        There is no evidence of pulmonary edema or pleural effusion
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        Is Riley's heart enlarged?

        Riley's heart shows moderate to severe cardiac enlargement
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        Technical Quality: Good

        Pulmonary Venous Congestion: No pulmonary venous congestion seen

        Pulmonary Infiltrate: No convincing interstitial changes are seen on the VD. Increased opacity is seen on the lateral, but may be due to the expiratory nature of the film.

        Other findings: Loss of serosal detail is noted on the abdominal portion of the film.

        Please review Riley's lab results

        SERUM CHEMISTRIES
        BUN 29 mg/dL, Normal: 6 - 25 mg/dL
        Creatinine 0.8 mg/dL, Normal: 0.5 - 1.6 mg/dL
        Sodium 145 mmol/L, Normal:139 - 154 mmol/L
        Potassium 4.5 mmol/L, Normal: 3.6 - 5.5 mmol/L
        Chloride 4.5 mmol/L, Normal: 3.6 - 5.5 mmol/L
        ALT 33 IU/L, Normal: 12 - 118 IU/L
        ALP 185 IU/L, Normal: 5 - 131 IU/L
        HEARTWORM
        Heartworm Test Results Negative within the last 6 months
        URINALYSIS
        Urinalysis - USG Not performed
        Urinalysis - Protein Not performed
        Urinalysis - Biochemical Not performed
        Urinalysis - Sediment Evaluation Not performed
        CBC
        White Blood Cells Not evaluated
        Red Blood Cells Not evaluated
        Platelets Not Evaluated

        Please reivew the results of Riley's echo. The images and videos were obtained by a cardiologist.

        Subjective - lesions of valves, myocardium, pericardial space No pericardial effusion; thickened mitral leaflets
         LV chamber size and thickness Mild left ventricular enlargement
         Left atrial size Moderate to severe dilation
         LVIDd & LVIDs Diastole (3.22 cm); Systole (1.41 cm)
         LV shortening fraction Normal to hyper dynamic ~ 56%
         RA, RV and Pulmonary Artery Moderate right atrial and ventricular enlargement, moderately dilated main pulmonary artery
         Effusions Moderate ascites seen
         Doppler results Mitral and tricuspid regurgitation; velocity of MR predicts normal systemic pressures; increased velocity of TR (~5.2 m/s) predicts severe pulmonary artery hypertension (~110 mmHg)
        Click here to view Riley's LV Echo
        Watch Riley's 4 chamber echo
        Watch Riley's MR echo
        Watch Riley's TR Echo
        Click here to view Riley's TR Echo  

        Under most circumstances, the identification of severe pulmonary hypertension as a cause for right sided congestive heart failure would require a referral to obtain the echocardiographic imaging found in this case.

        You're ready to form a diagnosis and treatment plan for Riley! Please select your answer to each question below.

        What is your diagnosis for Riley?

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        The following support you diagnosis: older age; predisposed breed; typical murmur of mitral regurgitation; and cardiomegaly. In Riley's case, the presence of significant pulmonary hypertension has led to right-sided CHF (ascites) rather than the more typical left-sided CHF that is common with MR due to valvular disease.
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        Which stage of heart disease is Riley in?

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        Riley is showing signs of heart failure due to heart disease
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        Click here to learn more about the stages of heart disease (ABCD Brochure)

        What treatment(s) would you recommend for Riley?

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        THE CEG RECOMMENDS:

        The CEG recommends treatment with Lasix, pimobendan, ACEi +/- Spironolactone.

         ACTUAL TREATMENT
         Initial Therapy Heartworm Prevention continued monthly preventative per referring veterinarian.

        Furosemide - 12.5 mg, 1 tablet - every 12 hours Given the degree of fluid increased dosing from 2 to 3 times a day is warranted.

        Enalapril - 2.5 mg, 1 tablet - every 12 hours. The dose was kept the same, as it is close to the 0.5 mg/kg dose.

        Pimobendan - 1.25 mg, 1 tablet - every 12 hours This was added given its benefit in CHF, as well as its potential value in the management of pulmonary hypertension. Doses of 1.875 mg or even as high as 2.5 mg could be given to this dog depending on response to therapy.

        Sildenafil - 20 mg, 1/2 tablet - every 8 hours. The use of sildenafil is recommended in the setting of severe pulmonary hypertension, as it is a particularly effective pulmonary arterial vasodilator.  Reducing pulmonary pressures can often help ameliorate clinical signs of pulmonary hypertension such as syncope, shortness of breath or tachypnea, as well as minimize the severity of right heart failure that can accompany severe PH.

        Spironolactone - 25 mg, 1/2 tablet - every 12 hours. Spironolactone has negligible diuretic effects; this drug is used to reduce the negative effects, but in used commonly in patients with right sided CHF to reduce retention due to chronic renin-antiotensin-aldosterone system activation. In addition, the drug is used to reduce pro-fibrotic effect of aldosterone on tissue such as cardiac muscle. The dose was increased to maximal value of 2 mg/kg twice daily.

         Diet Avoid high sodium treats and foods - such as processed meats, hot dogs, cheese, some table scraps.
         Other Points

        Abdominocentesis was performed - 1.4 L removed

        Recommended Follow-up A typical follow-up interval for a dog receiving treatment for CHF is 1 to 2 weeks for initial re-evaluation and 2 to 6 months thereafter. Specific follow-up intervals relate to the severity of disease and to the client's perception of current symptoms and the dog's quality of life.

        6-Month Follow-up:

        Riley was represented for evaluation of episodes of syncope, especially with excitement or exercise. Thoracic radiographs again showed no significant fluid (pleural effusion or pulmonary edema), but repeat echo identified a significant increase in the severity of the pulmonary hypertension (tricuspid regurgitation systolic velocity now 6.2 m/s, systolic gradient=150mmHg). The next step suggested to Riley's owner involved increasing the sildenafil dose (to 12mg q 8hrs, attainable by reformulating 20 mg tablets into a liquid form).

         

        To qualify for CE credit, please answer the following 5 questions.

        Which of the following findings defines Riley as being in congestive heart failure?

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        You are correct.
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        Which of the following drug effects makes sildenafil useful in the treatment of pulmonary hypertension?

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        You are correct
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        The diagnosis of pulmonary hypertension is best evaluated on echo by interrogations of what flow?

        You are correct.
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        Which of the following conditions best explains the cause of Riley’s pulmonary hypertension?

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        The presence of pulmonary hypertension can cause what clinical signs?

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        You are correct.
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        EVALUATION SURVEY

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