Podcast
Questions and Answers
What happens to the preload during severe tachycardias?
What happens to the preload during severe tachycardias?
Which of the following is NOT a clinical sign associated with the overt phase of DCM?
Which of the following is NOT a clinical sign associated with the overt phase of DCM?
In the preclinical phase of dilated cardiomyopathy, which of the following symptoms might be experienced?
In the preclinical phase of dilated cardiomyopathy, which of the following symptoms might be experienced?
What does the presence of a systolic murmur at the left apex indicate in a physical examination?
What does the presence of a systolic murmur at the left apex indicate in a physical examination?
Signup and view all the answers
Which condition is typically associated with abdominal distension in breeds such as Irish Wolfhounds and Newfoundlands?
Which condition is typically associated with abdominal distension in breeds such as Irish Wolfhounds and Newfoundlands?
Signup and view all the answers
Which breed is NOT classified as a large breed dog?
Which breed is NOT classified as a large breed dog?
Signup and view all the answers
What is a primary function of the Renin-Angiotensin-Aldosterone System (RAAS)?
What is a primary function of the Renin-Angiotensin-Aldosterone System (RAAS)?
Signup and view all the answers
How does dilated cardiomyopathy typically affect stroke volume?
How does dilated cardiomyopathy typically affect stroke volume?
Signup and view all the answers
Which of the following is a consequence of advanced dilated cardiomyopathy?
Which of the following is a consequence of advanced dilated cardiomyopathy?
Signup and view all the answers
What arrhythmia is characterized by the absence of P waves?
What arrhythmia is characterized by the absence of P waves?
Signup and view all the answers
Which of the following is a result of neurohormonal activation in DCM?
Which of the following is a result of neurohormonal activation in DCM?
Signup and view all the answers
What effect do arrhythmias have on cardiac output (CO)?
What effect do arrhythmias have on cardiac output (CO)?
Signup and view all the answers
What structural change occurs in the heart due to cardiac remodeling associated with DCM?
What structural change occurs in the heart due to cardiac remodeling associated with DCM?
Signup and view all the answers
Which disease is characterized by poor contraction and decreased cardiac output?
Which disease is characterized by poor contraction and decreased cardiac output?
Signup and view all the answers
What is the expected ejection fraction (EF%) in a dog with severe DCM?
What is the expected ejection fraction (EF%) in a dog with severe DCM?
Signup and view all the answers
What is a common characteristic of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)?
What is a common characteristic of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)?
Signup and view all the answers
What is the primary treatment for dogs diagnosed with ARVC?
What is the primary treatment for dogs diagnosed with ARVC?
Signup and view all the answers
In which animal is Arrhythmogenic Right Ventricular Cardiomyopathy predominantly observed?
In which animal is Arrhythmogenic Right Ventricular Cardiomyopathy predominantly observed?
Signup and view all the answers
What diagnostic tool is most likely to reveal positive VPCs in a dog suspected of having ARVC?
What diagnostic tool is most likely to reveal positive VPCs in a dog suspected of having ARVC?
Signup and view all the answers
What is a potential complication of ARVC in dogs?
What is a potential complication of ARVC in dogs?
Signup and view all the answers
What treatment option is recommended for dogs exhibiting clinical signs of syncope or weakness due to ARVC?
What treatment option is recommended for dogs exhibiting clinical signs of syncope or weakness due to ARVC?
Signup and view all the answers
Which genetic factor is associated with the familial form of ARVC in Boxers?
Which genetic factor is associated with the familial form of ARVC in Boxers?
Signup and view all the answers
What indicates that treatment for ARVC should be initiated?
What indicates that treatment for ARVC should be initiated?
Signup and view all the answers
Which symptom is NOT associated with nutritional secondary cardiomyopathies?
Which symptom is NOT associated with nutritional secondary cardiomyopathies?
Signup and view all the answers
What is the prognosis for dogs with hypertrophic cardiomyopathy?
What is the prognosis for dogs with hypertrophic cardiomyopathy?
Signup and view all the answers
What pattern of fractional shortening indicates normal cardiac function?
What pattern of fractional shortening indicates normal cardiac function?
Signup and view all the answers
Which physical examination finding is NOT typically associated with congestive heart failure (CHF)?
Which physical examination finding is NOT typically associated with congestive heart failure (CHF)?
Signup and view all the answers
For a dog to be diagnosed with dilated cardiomyopathy (DCM), how many ventricular premature contractions (VPCs) are significant over a 24-hour Holter monitoring period?
For a dog to be diagnosed with dilated cardiomyopathy (DCM), how many ventricular premature contractions (VPCs) are significant over a 24-hour Holter monitoring period?
Signup and view all the answers
What is the recommended action when genetic testing for PDK4 and Titin genes is conducted?
What is the recommended action when genetic testing for PDK4 and Titin genes is conducted?
Signup and view all the answers
What biomarker is useful for detecting cardiac enlargement in Dobermans?
What biomarker is useful for detecting cardiac enlargement in Dobermans?
Signup and view all the answers
What does a La:Ao ratio greater than 2 indicate in an echocardiogram?
What does a La:Ao ratio greater than 2 indicate in an echocardiogram?
Signup and view all the answers
What was the median time to primary endpoint for dogs receiving pimobendan in the PROTECT study?
What was the median time to primary endpoint for dogs receiving pimobendan in the PROTECT study?
Signup and view all the answers
Which of the following is a plausible consequence of incomplete genetic penetrance in dogs undergoing genetic testing for DCM?
Which of the following is a plausible consequence of incomplete genetic penetrance in dogs undergoing genetic testing for DCM?
Signup and view all the answers
What is the critical first step for Stage A management in DCM?
What is the critical first step for Stage A management in DCM?
Signup and view all the answers
Which treatment is appropriate for dogs in Stage B2 with systolic dysfunction?
Which treatment is appropriate for dogs in Stage B2 with systolic dysfunction?
Signup and view all the answers
What is a negative predictor for survival in Stage C DCM?
What is a negative predictor for survival in Stage C DCM?
Signup and view all the answers
What is the recommended action if a dog has resting respiratory rates above 35 per minute?
What is the recommended action if a dog has resting respiratory rates above 35 per minute?
Signup and view all the answers
Which factor is a common secondary cause of systolic dysfunction in dogs?
Which factor is a common secondary cause of systolic dysfunction in dogs?
Signup and view all the answers
What should be monitored in suspected cases of nutritional cardiomyopathy?
What should be monitored in suspected cases of nutritional cardiomyopathy?
Signup and view all the answers
In the context of BEG diets, what is a possible hypothesis regarding DCM?
In the context of BEG diets, what is a possible hypothesis regarding DCM?
Signup and view all the answers
Which of the following would NOT be included in the treatment for Diet-associated DCM?
Which of the following would NOT be included in the treatment for Diet-associated DCM?
Signup and view all the answers
Which breed is notably associated with taurine deficiency and nutritional cardiomyopathy?
Which breed is notably associated with taurine deficiency and nutritional cardiomyopathy?
Signup and view all the answers
What indicates a potential heart failure in dogs during Stage C DCM?
What indicates a potential heart failure in dogs during Stage C DCM?
Signup and view all the answers
What is a common diagnostic marker often elevated in cases of myocarditis?
What is a common diagnostic marker often elevated in cases of myocarditis?
Signup and view all the answers
What is a common misconception about dogs with diet-associated DCM concerning taurine levels?
What is a common misconception about dogs with diet-associated DCM concerning taurine levels?
Signup and view all the answers
Which infectious agents are known to cause myocarditis?
Which infectious agents are known to cause myocarditis?
Signup and view all the answers
During the chronic stage of Chagas disease myocarditis, what condition is commonly observed?
During the chronic stage of Chagas disease myocarditis, what condition is commonly observed?
Signup and view all the answers
What is the primary goal in managing tachycardia induced cardiomyopathy?
What is the primary goal in managing tachycardia induced cardiomyopathy?
Signup and view all the answers
What is a primary characteristic of myocarditis in terms of myocardial structure?
What is a primary characteristic of myocarditis in terms of myocardial structure?
Signup and view all the answers
What is the typical diagnostic procedure for confirming Chagas disease myocarditis?
What is the typical diagnostic procedure for confirming Chagas disease myocarditis?
Signup and view all the answers
What is the role of L-carnitine in myocardial health?
What is the role of L-carnitine in myocardial health?
Signup and view all the answers
Study Notes
Canine Myocardial Diseases
- The presentation is about canine myocardial diseases, specifically cardiomyopathies.
- A Cardiologist, Eduardo J Benjamin, DVM, MS presented the information on December 10, 2024.
- Objectives include describing causes, complications, physical exam findings, diagnostic tools, and management for dogs with myocardial disease.
Myocardial Disease
- Myocardial disease affects the heart muscle.
- It is not caused by valve, endocardial, or pericardial problems.
- Key characteristics include decreased contractility and arrhythmias.
Canine Cardiomyopathies
-
Dilated Cardiomyopathy (DCM):
- A primary form of DCM exists, DCM.
- Secondary causes include nutritional imbalances (L-carnitine, taurine, certain "grain-free" and BEG diets), myocarditis, infiltrative diseases, tachycardia-induced cardiomyopathy, and drug-induced cardiomyopathy (e.g., doxorubicin).
-
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC):
- ARVC is a type of canine cardiomyopathy.
-
Hypertrophic Cardiomyopathy (HCM):
- HCM is a common type of canine cardiomyopathy.
-
Atrial Standstill/Atrial Cardiomyopathy:
- A condition involving the atria of the heart.
Cardiovascular System Functions
- Blood pressure equals cardiac output (CO) multiplied by systemic vascular resistance (SVR).
- CO equals stroke volume (SV) multiplied by heart rate (HR).
- Stroke volume is determined by preload, afterload, and contractility.
Dilated Cardiomyopathy (Primary)
- Characterized by dilation and systolic dysfunction.
- Usually considered primary or idiopathic.
- Diagnosed via exclusion of other possible causes.
- Genetic mutations are present in some cases (i.e.Pdk4 and Titin in Dobermans).
Genetics of Dilated Cardiomyopathy
- In human cases, 30-50% are familial.
- Over 50 mutations have been identified in humans.
- In dogs, the prevalence is high in certain breeds such as Dobermans, Irish Wolfhounds, and some other large breeds.
- Several genetic mutations have been identified in dogs, including PDK4 ('DCM1') and Titin ('DCM 2).
- Several modes of inheritance have been identified within the breed (i.e. Irish Wolfhound, autosomal recessive).
Breeds Commonly Affected by DCM
- Large breed dogs, often males, in middle age are most affected.
- Breeds commonly affected include Doberman Pinschers, Boxers, Irish Wolfhounds, Great Danes, Portuguese Water Dogs, English Cocker Spaniels, and American Cocker Spaniels.
Incidence and Prevalence of MVD vs DCM
- A graph demonstrates the different incidences of mitral valve degeneration (MVD) and canine dilated cardiomyopathy (DCM) across different dog weights.
Pathogenesis of DCM
- Poor contraction (systolic dysfunction) leads to less volume ejected and decreased cardiac output.
- Compensatory mechanisms (Renin-Angiotensin-Aldosterone System - RAAS) increase preload to regulate blood pressure via water retention.
Decreased Stroke Volume in DCM
- Normal contractility is an EF% of approximately 70%.
- DCM shows decreased contractility EF of approximately 25%.
Renin-Angiotensin-Aldosterone System
- A hormonal system regulating blood pressure, primarily through water and salt balance. Detailed presentation on the components.
Advanced Dilated Cardiomyopathy
- Severe DCM can be identified by lower than typical ejection fraction.
Pathogenesis of DCM
- Neurohormonal activation (RAAS) causes sodium and water retention and increased preload.
- Cardiac remodeling, including eccentric hypertrophy and fibrosis, occurs.
- Abnormal systolic/diastolic function and arrhythmias are present.
- The above contributes to the progression of heart disease.
Clinical Consequences of DCM
- Congestive Heart Failure: Signs might include pulmonary edema.
- Arrhythmias: This may involve the presence of normal and abnormal patterns on an ECG.
- Weakness/Syncope: Reduced cardiac output leads to less oxygen to the brain.
How do Arrhythmias Decrease Cardiac Output?
- Heart filling during diastole is reduced with the presence of severe tachycardia
- Preload is decreased as diastolic time becomes shorter, resulting in lower stroke volume (SV) and cardiac output (CO).
Dilated Cardiomyopathy Efficiency
- Insufficient cardiac output and reduced cardiac efficiency result primarily from decreased preload.
Tachyarrhythmias and Cardiac Output
- Tachyarrhythmias result in decreased cardiac output due to decreased preload.
Clinical Course of DCM
- Three phases, including genetic predisposition (Stage A), preclinical (occult) phase (Stage B), and clinical (overt) phase (Stage C).
"Occult" DCM
- "Occult" DCM has no noticeable clinical signs initially.
History and Clinical Signs of DCM
- There may be no clinical signs in the occult phase.
- Respiratory signs like coughing, rapid breathing and abdominal distension can occur.
- Exercise intolerance, weakness, and weight loss can be evident.
Physical Exam Findings for DCM
- Soft systolic murmurs might be heard at the left apex, without the presence of a murmur not ruling out DCM.
- Gallop sounds (S3) can be heard.
- Weak peripheral pulses or pulse deficits may be observed.
- Jugular venous distention or pulsation is common.
Physical Exam for CHF
- Pale/cyanotic mucous membranes
- Pulmonary crackles, indicative of fluid accumulation in the lungs.
- Tachypnea or dyspnea (rapid/labored breathing).
- Tachycardia (rapid heart rate).
- Hypothermia (low body temperature).
- Presence of a fluid wave.
Diagnosis - Echocardiogram
- Fractional shortening can be calculated from echocardiogram data (LVIDs and LVIDs).
- LV end-diastolic volume and LV end-systolic volume are used to determine ejection fraction.
- The ratio of left atrium to aorta (LA:Ao) is measured.
Diagnosis - Electrocardiogram
- 300 or more ventricular premature complexes (VPCs) in a 24-hour Holter monitor are used to aid in diagnosis.
Diagnosis - Thoracic Radiographs
- Normal cardiac silhouette does not necessarily rule out systolic dysfunction.
Diagnosis - Biomarkers
- NT-proBNP can be elevated with cardiac enlargement.
- Cardiac Troponin I is elevated with myocardial cellular damage.
Genetic Testing
- Genetic testing is not preferred for screening, but can be useful when considering breeding pairs.
- Absence/presence of mutations does not ensure a patient will/will not develop DCM.
- Incomplete genetic penetrance exists.
Absence of Left Apical Murmur and DCM
- Absence of a left apical murmur does not rule out DCM.
Diagnostic Tests for Dilated Cardiomyopathy (DCM)
- Echocardiography
- ECG/Holter Monitor
- Thoracic Radiographs
- Biomarkers (NT-proBNP, Cardiac Troponin I)
- Genetic testing
Screening for DCM
- Goal: Identify disease early in the occult phase.
Pimobendan Randomized Occult DCM Trial
- The study, called PROTECT, looks further into pimobendan for slowing or delaying progression of the disease.
Ace Inhibitors During Preclinical DCM
- Benazepril given to dogs may delay onset of CHF and/or sudden cardiac death.
Treatment for Dogs with Overt DCM
- The presentation includes treatments for overt DCM
- Inotropic Support (Pimobendan, Dobutamine, Digoxin).
- Afterload Reduction (Pimobendan, ACE inhibitors, Amlodipine).
- Ventricular Arrhythmia Control (Lidocaine/Mexiletine, Sotalol, Amiodarone).
- Supraventricular Arrhythmias (Diltiazem, Digoxin, Amiodarone).
- Preload Reduction (Furosemide.
- Low-sodium diet.
Treatment for Dogs with Ventricular Arrhythmias
- Class I drugs (e.g., Lidocaine, Mexiletine, Procainamide).
- Class III drugs (e.g., Sotalol, Amiodarone).
Summary/Staging of DCM
- The presentation outlines several stages for diagnosing and treating DCM in dogs (A, B1, B2, C, and D).
Prognosis of DCM (Stage C)
- Typical survival time is <1 year (usually 6 months).
- Negative predictors for survival include ascites, atrial fibrillation and significantly decreased left ventricular function.
Monitoring for Recurrent CHF
- Home monitoring of resting respiratory rate is an excellent way to proactively detect recurrent heart failure. Frequency should be daily.
Secondary Causes of Systolic Dysfunction
- Volume or pressure overload.
- Metabolic issues such as tachycardia.
- Nutritional deficiencies.
- Toxic exposure/ingestion.
- Infiltrative diseases like myocarditis.
- Ischemic heart disease.
Nutritional Cardiomyopathy
- 2018 increase in reported DCM cases from non-traditional diets ("BEG" diets).
- Some specific common ingredients implicated are boutique/exotic proteins or carbohydrates, grain-free diets and several types of home-prepared diets.
- Potential causes include deficiencies and altered bioavailability of nutrients or inadvertent inclusion of toxins (pesticides, mycotoxins, additives).
Diagnosis - Nutritional Cardiomyopathy
- Echocardiogram, Diet History, Taurine levels (plasma & whole blood), and response to therapy/diet changes.
Treatment for Diet-Associated DCM
- Treat DCM similar to primary DCM, including diet changes (switch to standard diet if allergy free).
- Check taurine levels in suspected patients.
- Report to FDA any suspected cases.
Outcome of DCM
- Reverse remodeling of the heart is possible in diet-associated cases.
Taurine - Amino Acid
- Critical amino acid for cardiovascular and retinal function.
L-Carnitine
- Important in transporting fatty acids into mitochondria.
Myocarditis
- Myocarditis is diagnosed with myocardial necrosis and inflammation.
- Due to physical trauma or infections (e.g., various viruses, protozoa, bacteria, fungi).
Chagas Disease Myocarditis
- Low but increasing prevalence in dogs, often originating in Texas.
- Rapid RV (right ventricle) infection/damage.
- Common signs are sudden death, bradycardia, or tachycardia; severe acute CHF.
- Chronic stage is characterized by gradual progression of heart dysfunction, which is similar to idiopathic DCM.
Diagnosis of Chagas Disease Myocarditis
- Antibody titers (IFA) may be positive.
- Examination for trypomastigotes and amastigotes in tissue or blood.
Tachycardia-Induced Cardiomyopathy
- Sustained rapid heart rate.
- Potentially reversible cardiac dysfunction.
- Ablation may be a useful treatment option.
Metabolic Hypothyroidism
- Reduced adrenergic receptor number and Na+/K+ ATPase activity, among other potential factors.
Drug-Related Cardiomyopathy - Doxorubicin
- Doxorubicin is a primary cause and often dose-dependent.
- Cardiotoxicity can be severe.
- No specific therapy exists.
Hypertrophic Cardiomyopathy
- Differential diagnosis to rule out concentric hypertrophy.
- Shi Tzu and Terrier breeds are largely affected (though generally subclinical).
- A significant proportion progress to congestive heart failure (CHF), and a portion die suddenly.
- Survival time of approximately 8-14 months after diagnosis.
Atrial Myopathy/Persistent Atrial Standstill
- Specific breeds (English Springer Spaniels and Labrador Retrievers).
- Characterized by damage to atrial myocardium.
- This can lead to persistent atrial standstill, bradycardia, and other related clinical signs.
- Pacemaker implant is sometimes a suitable treatment option.
Which Diagnostic Test is Best for ARVC?
- A Holter monitor is suggested as the best clinical diagnostic tool in ARVC cases.
A Normal Echocardiogram and ARVC
- A normal echocardiogram does not completely rule out ARVC.
Contact Information
- Email address for questions: [email protected]
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on dilated cardiomyopathy and related cardiac concepts. This quiz covers clinical signs, symptoms, and the physiological effects of the disease. Understand how different factors influence heart function and structural changes associated with cardiomyopathy.
