Difference between revisions of "Dilated Cardiomyopathy"

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Also know as: '''''DCM — Congestive Cardiomyopathy'''''
 
  
−
== Introduction  ==
 
  
−
Dilated cardiomyopathy (DCM) is characterized by progressive '''systolic dysfunction''' (loss of myocardial contractile function) and '''ventricular dilation''' (eccentric hypertrophy). This is the most common form of cardiomyopathy in dogs. There are breed predispositions and familial distributions, suggesting an underlying causal genetic mutation. An autosomal dominant inheritance pattern with incomplete and age-dependent penetrance has been reported.
+
''a.k.a. Congestive Cardiomyopathy''
 +
*Common in dogs
  
−
==Signalment==
+
*Rare in cats (with adequate taurine supplementation)
  
−
'''Giant and large breeds''' are most at risk. Predisposed breeds include: Irish Wolfhound, Great Dane, Newfoundland, Leonberger, St. Bernard, Dobermann Pinscher, Boxer, Dogue de Bordeaux and the Portuguese Water dog.
+
===Signalment===
  
−
Prevalence increases with age and the typical age at diagnosis is 6-8 years. A severe juvenile form is recognized in the Portuguese Water dog.
+
'''Dog:''' Giant and Large Breeds (e.g. Dobermann pinscher, Boxer, Great Dane); Male>Female; Risk increases with age
  
−
Male dogs are more frequently affected than females, particularly in Doberman Pinschers.
+
'''Cat:''' Greatest risk in: Siamese, Burmese, Abyssinian; Male>Female; Middle Age & Old Age
  
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== Clinical Signs ==
+
===Description===
  
−
The natural history of the disease is described in two phases.  
+
*Dilated cardiomyopathy (DCM) occurs when there is a progressive reduction in systolic myocardial contractility.  Decreased myocardial contractility affects the removal of blood from the ventricle at systole.  A larger volume of blood increases the end diastolic pressures causing dilation of the ventricle and the development of eccentric hypertrophy.
  
−
The '''asymptomatic (occult) phase''' is when no clinical signs are apparent, but there may be structural, functional or electrical abnormalities. These include increased left ventricular and left atrial internal diameter, reduced myocardial contractility and ventricular premature contractions. The duration of this occult phase is variable and can last from months to years.
 
  
−
The '''overt clinical phase''' is when clinical signs, such as congestive heart failure (CHF), syncope and exercise intolerance, develop. Arrhythmias are common in this stage.
+
===Diagnosis===
  
−
== Diagnosis ==
+
====History & Clinical Signs====
−
===History and Physical Examination===
 
  
−
Asymptomatic (occult) phase
+
-Asymptomatic (Occult) DCM: See in predisposed breeds (e.g. Doberman pinschers)
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* Physical examination may be unremarkable
 
−
* Soft, systolic heart murmur
 
−
* Arrhythmia with pulse deficits
 
  
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Overt clinical phase
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-'''Right-Sided Congestive Heart Failure Signs'''
−
* History may include: exercise intolerance, lethargy, anorexia, muscle wasting (cardiac cachexia), syncope, abdominal distension (ascites)
 
−
* Systolic heart murmur
 
−
* Arrhythmia with pulse deficits
 
−
* Increased respiratory rate and effort, increased bronchovesicular sounds, pulmonary crackles (left-sided congestive heart failure)
 
−
* Weakness
 
−
* Jugular venous distension and/or jugular pulsation, hepatomegaly, ascites (right-sided congestive heart failure)
 
  
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===Thoracic Radiographs===
+
*Giant Breeds usually prone to these
−
Radiographs are performed in the clinical phase to diagnose congestive heart failure and monitor response to treatment.
 
  
−
===Electrocardiography (ECG)===
+
-'''Left-Sided Congestive Heart Failure Signs'''
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A normal ECG does not rule out the presence of DCM, but is the test of choice for detecting arrhythmias. In the occult phase, arrhythmias may be the first indication of disease. The following are associated with a high index of suspicion for occult DCM:
 
−
* One or more VPC in an at-risk breed
 
−
* Atrial fibrillation appears to be an early sign of disease in Irish Wolfhounds, whereas other breeds develop atrial fibrillation in advanced disease.
 
−
* 24 hour Holter ECG recording:
 
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** Greater than 100 VPCs is suggestive of DCM or ARVC
 
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** Between 50 and 100 VPCs in an at-risk breed is suspicious. Holter recording should be repeated in 3-6 months.
 
  
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During the clinical phase, the following may be detected:
+
*Boxers and Doberman pinschers have a higher risk
−
* Occasional VPCs or superventricular premature complexes (SVPCs)
 
−
* Ventricular tachycardia
 
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* Atrial fibrillation
 
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* Left bundle branch block morphology
 
  
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===Echocardiography===
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-Syncope
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Echocardiographic changes may include left ventricular dilation (increased  left ventricular end-diastolic diameter), systolic dysfunction (reduced myocardial contractility), mitral regurgitation secondary to dilation of the mitral annulus and atrial enlargement.
 
  
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===Blood Tests===
+
-Weight Loss
−
Changes on serum biochemistry analysis may include [[azotemia]], this is common in dogs receiving diuretic therapy and is usually pre-renal in nature. Electrolyte abnormalities, such as mild hyponatraemia and hypokalaemia, are also common in dogs with congestive heart failure.
 
  
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'''Cardiac biomarkers''', NT-proBNP and cardiac troponin I (cTnI), may be helpful in detecting DCM. Troponin I may be elevated in cardiac disease and will also be elevated as a consequence of haemodynamically significant arrhythmias. Plasma concentrations of NT-proBNP may be elevated in pre-clinical disease and increase with severity. It is important to note that neither biomarker is specific to DCM and merely indicates the heart is under stress/stretch (NT-proBNP) or that there is damage to cardiomyocytes (cTnI).
+
-Dyspnoea
  
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'''Taurine''' deficiency may contribute to a DCM phenotype in the American Cocker Spaniel, Dalmatian, Labrador Retriever and Golden Retriever. Most dogs with taurine-deficient DCM will have plasma taurine levels <25nmol/L. This is important to recognize, as in these cases cardiac function and prognosis can be substantially improved by taurine supplementation.
+
-Lethargy
  
−
<br>
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-Weakness
  
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== Treatment and Control ==
+
-Hindlimb Paresis (cats with saddle thrombi)
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===Asymptomatic (Ocult) phase===
 
−
'''Pimobendan''' has recently been demonstrated to prolong the time to onset of clinical signs and extend survival in Dobermans with asymptomatic (occult) DCM.
 
  
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===Clinical phase===
 
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In the clinical phase, treatment involves the use of diuretics, ACE inhibitors and positive inotropes. Antiarrhythmic drugs may also be necessary.
 
  
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<br>
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====Physical Exam====
  
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== Prognosis ==
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-Systolic Murmur
  
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Prognosis from the onset of occult DCM is variable and can be years. Once clinical signs have developed, the prognosis is poor with a median survival time of 3-6 month depending on the breed. Death is usually due to refractory congestive heart failure or sudden death. The prevalence of sudden death is particularly high in Doberman Pinschers with DCM (30-50%).
+
-Gallop Rhythm
  
 +
-S3 Heart Sound (+/-)
  
 +
-Arrhythmias
  
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<br>
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-Pulse Deficits
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{{Learning
 
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|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis00923.asp, Dilated cardiomyopathy]<br>[https://www.vetstream.com/canis/Content/Illustration/ill33682.asp, DCM - long axis ultrasound]
 
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|flashcards = [[Myocardial Pathology Flashcards]]
 
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}}
 
  
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== References==
+
-Pulmonary crackles
−
Tilley, L.P, Smith, F.W.K., Oyama, M.A, Sleeper, M.M (2008) '''Manual of Canine and Feline Cardiology''' (Fourth Edition) ''W.B. Saunders Company''
 
  
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{{citation
 
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|initiallast = Summerfield
 
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|initialfirst = N.J.
 
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|initiallast = Boswood
 
−
|initialfirst = A.
 
−
|initiallast = O'Grady
 
−
|initialfirst = M.R.
 
−
|initiallast = Gordon
 
−
|initialfirst = S.G.
 
−
|initiallast = Dukes-McEwan
 
−
|initialfirst = J.
 
−
|initiallast = Oyama
 
−
|initialfirst = M.A.
 
−
|initiallast = Smith
 
−
|initialfirst = S.
 
−
|initiallast = Patteson
 
−
|initialfirst = M.
 
−
|initiallast = French
 
−
|initialfirst = A.T.
 
−
|initiallast = Culshaw
 
−
|initialfirst = G.J.
 
−
|initiallast = Braz-Ruivo
 
−
|initialfirst = L.
 
−
|initiallast = Estrada
 
−
|initialfirst = A.
 
−
|initiallast = O'Sullivan
 
−
|initialfirst = M.L.
 
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|initiallast = Loureiro
 
−
|initialfirst = J.
 
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|initiallast = Willis
 
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|initialfirst = R.
 
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|initiallast = Watson
 
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|initialfirst = P.
 
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|year = 2012
 
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|jtitle = Efficacy of Pimobendan in the Prevention of Congestive Heart Failure or Sudden Death in Doberman Pinschers with Preclinical Dilated Cardiomyopathy (The PROTECT Study)
 
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|jor = Journal of Veterinary Internal Medicine
 
−
|vol = 26(6)
 
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|Range = 1337–1349
 
−
}}
 
  
 +
====Laboratory Findings====
  
 +
-Azotemia
  
 +
-Elevated Liver Enzymes (+ Liver Congestion)
  
 +
-Signs of congestive heart failure
  
 +
-Signs of thromboembolism (cats)
  
−
{{review}}
+
-Plasma taurine reduction (cats)
  
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{{OpenPages}}
+
 
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[[Category:Cardiac Diseases - Dog]][[Category:Cardiovascular Diseases - Cat]]
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====Radiography====
−
[[Category:Cardiomyopathy]] [[Category:Expert_Review]]
+
 
−
[[Category:Cardiology Section]]
+
-Left Ventricular Hypertrophy (Seen in Dobermans & Boxers)
 +
 
 +
-Left Atrial Enlargement (Seen in Dobermans & Boxers)
 +
 
 +
-Generalized Cardiomegaly (Seen in Giant Breeds)
 +
 
 +
-Left-Sided Congestive Heart Failure signs (pulmonary congestion & edema)
 +
 
 +
-Right-Sided Congestive Heart Failure signs (pleural effusion, ascites)
 +
 
 +
 
 +
====Electrocardiography (ECG)====
 +
 
 +
-Rhythm Disturbances (e.g. Atrial fibrillation (Giant Breeds); Ventricular Arrhythmias (Doberman pinchers, Boxers))
 +
 
 +
-Conduction Disturbances
 +
 
 +
-Characteristic signs of hypertrophy
 +
 
 +
 
 +
====Echocardiography====
 +
 
 +
-Hypokinetic left ventricle (i.e. reduced fractional shortening therefore reduced contractility)
 +
 
 +
-Reduced ejection fraction (i.e. % end diastolic volume ejected at systole)
 +
 
 +
-Decreased ventricular wall thickness
 +
 
 +
-Left atrial enlargement
 +
 
 +
-Mitral regurgitation
 +
 
 +
 
 +
===Treatment===
 +
 
 +
-Treat congestive heart failure (Reduce Preload & Afterload; Improve Systolic Function; Control Cardiac Arrhythmias)
 +
 
 +
-Therapeutic thoracocentesis (To remove pleural effusion) (cats)
 +
 
 +
-Taurine Supplementation (cats)
 +
 
 +
===Prognosis===
 +
 
 +
'''Dogs'''
 +
 
 +
-Poor: Most breeds survive 6-12 months
 +
 
 +
-Grave: Dobermans and Boxers
 +
 
 +
'''Cats'''
 +
 
 +
-Good: When cardiomyopathy results from taurine deficiency
 +
 
 +
-Grave: Other causes of cardiomyopathy
 +
 
 +
==From Pathology==
 +
 
 +
''Incidence:''
 +
 
 +
Most common form in the dog.  Seen in young to middle aged dogs of large breeds:
 +
*St Bernard
 +
*Great Dane
 +
 
 +
''Clinical signs:''
 +
 
 +
Disease is a slowly progressive dilation of the ventricles with a loss of contractility.  This is seen histologically as random myofibrillar thinning and degeneration of myocyte mitochonria, although it is possible that no histological lesions are present. 
 +
 
 +
Clinical signs will appear as a sudden onset disease as there will be an acute decompensation for the pathology that had accumulated gradually.  Signs include those of a congestive heart failure:
 +
*Pulmonary oedema.
 +
*Ascites.
 +
*Hepatomegaly and splenomegaly.
 +
 
 +
''Diagnosis:''
 +
 
 +
Gross cardiomegaly with cardiac hypertrophy, dilation and decreased contractility. 
 +
Histopathologically; increased ''attenuated wavy fibres'' within the myocardium.  Fibres are thinner than normal and have a wavy appearance.  May develop due to a chronic volume overload.
 +
 
 +
*Ventricular dilation, particularly the left ventricle, distorts the AV-valves which often become incompetant. 
 +
*'''Fibrillation''' is a common finding as dilation of the myocardium induces abnormal electrical activity and arrhythmias.
 +
 
 +
Variations of the disease exist in specific breeds:
 +
*'''Doberman''': Present with arrhythmias.  Histologically there are lymphocytic infiltrates within the ventricular myocardium.  See focal degeneration of the bundle of His, probably due to narrowing of small vessels near the conductive tissue.
 +
*'''English Cockers:''' Familial with many dogs having sub-clinical disease.
 +
 
 +
 
 +
[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_Ssrch View images courtesy of Cornell Veterinary Medicine]
 +
 
 +
 
 +
====Secondary to toxic agents====
 +
 
 +
Includes:
 +
*Dilated myopathy in horses with '''monensin''' toxicity.
 +
*Dilated myopathy in dogs with long term administration of '''doxorubicin'''.
 +
*Dilated myopathy in cats due to '''taurine''' deficiency.
 +
 
 +
==Test yourself with the Myocardial Pathology Flashcards==
 +
 
 +
[[Myocardial_Pathology_Flashcards_-_Pathology|Myocardial Pathology Flashcards]]
 +
 
 +
[[Category:Cardiomyopathy]]
 +
[[Category:To_Do_-_Cardiovascular]]

Revision as of 16:28, 15 December 2010


 This article is still under construction.



a.k.a. Congestive Cardiomyopathy

  • Common in dogs
  • Rare in cats (with adequate taurine supplementation)

Signalment

Dog: Giant and Large Breeds (e.g. Dobermann pinscher, Boxer, Great Dane); Male>Female; Risk increases with age

Cat: Greatest risk in: Siamese, Burmese, Abyssinian; Male>Female; Middle Age & Old Age

Description

  • Dilated cardiomyopathy (DCM) occurs when there is a progressive reduction in systolic myocardial contractility. Decreased myocardial contractility affects the removal of blood from the ventricle at systole. A larger volume of blood increases the end diastolic pressures causing dilation of the ventricle and the development of eccentric hypertrophy.


Diagnosis

History & Clinical Signs

-Asymptomatic (Occult) DCM: See in predisposed breeds (e.g. Doberman pinschers)

-Right-Sided Congestive Heart Failure Signs

  • Giant Breeds usually prone to these

-Left-Sided Congestive Heart Failure Signs

  • Boxers and Doberman pinschers have a higher risk

-Syncope

-Weight Loss

-Dyspnoea

-Lethargy

-Weakness

-Hindlimb Paresis (cats with saddle thrombi)


Physical Exam

-Systolic Murmur

-Gallop Rhythm

-S3 Heart Sound (+/-)

-Arrhythmias

-Pulse Deficits

-Pulmonary crackles


Laboratory Findings

-Azotemia

-Elevated Liver Enzymes (+ Liver Congestion)

-Signs of congestive heart failure

-Signs of thromboembolism (cats)

-Plasma taurine reduction (cats)


Radiography

-Left Ventricular Hypertrophy (Seen in Dobermans & Boxers)

-Left Atrial Enlargement (Seen in Dobermans & Boxers)

-Generalized Cardiomegaly (Seen in Giant Breeds)

-Left-Sided Congestive Heart Failure signs (pulmonary congestion & edema)

-Right-Sided Congestive Heart Failure signs (pleural effusion, ascites)


Electrocardiography (ECG)

-Rhythm Disturbances (e.g. Atrial fibrillation (Giant Breeds); Ventricular Arrhythmias (Doberman pinchers, Boxers))

-Conduction Disturbances

-Characteristic signs of hypertrophy


Echocardiography

-Hypokinetic left ventricle (i.e. reduced fractional shortening therefore reduced contractility)

-Reduced ejection fraction (i.e. % end diastolic volume ejected at systole)

-Decreased ventricular wall thickness

-Left atrial enlargement

-Mitral regurgitation


Treatment

-Treat congestive heart failure (Reduce Preload & Afterload; Improve Systolic Function; Control Cardiac Arrhythmias)

-Therapeutic thoracocentesis (To remove pleural effusion) (cats)

-Taurine Supplementation (cats)

Prognosis

Dogs

-Poor: Most breeds survive 6-12 months

-Grave: Dobermans and Boxers

Cats

-Good: When cardiomyopathy results from taurine deficiency

-Grave: Other causes of cardiomyopathy

From Pathology

Incidence:

Most common form in the dog. Seen in young to middle aged dogs of large breeds:

  • St Bernard
  • Great Dane

Clinical signs:

Disease is a slowly progressive dilation of the ventricles with a loss of contractility. This is seen histologically as random myofibrillar thinning and degeneration of myocyte mitochonria, although it is possible that no histological lesions are present.

Clinical signs will appear as a sudden onset disease as there will be an acute decompensation for the pathology that had accumulated gradually. Signs include those of a congestive heart failure:

  • Pulmonary oedema.
  • Ascites.
  • Hepatomegaly and splenomegaly.

Diagnosis:

Gross cardiomegaly with cardiac hypertrophy, dilation and decreased contractility. Histopathologically; increased attenuated wavy fibres within the myocardium. Fibres are thinner than normal and have a wavy appearance. May develop due to a chronic volume overload.

  • Ventricular dilation, particularly the left ventricle, distorts the AV-valves which often become incompetant.
  • Fibrillation is a common finding as dilation of the myocardium induces abnormal electrical activity and arrhythmias.

Variations of the disease exist in specific breeds:

  • Doberman: Present with arrhythmias. Histologically there are lymphocytic infiltrates within the ventricular myocardium. See focal degeneration of the bundle of His, probably due to narrowing of small vessels near the conductive tissue.
  • English Cockers: Familial with many dogs having sub-clinical disease.


View images courtesy of Cornell Veterinary Medicine


Secondary to toxic agents

Includes:

  • Dilated myopathy in horses with monensin toxicity.
  • Dilated myopathy in dogs with long term administration of doxorubicin.
  • Dilated myopathy in cats due to taurine deficiency.

Test yourself with the Myocardial Pathology Flashcards

Myocardial Pathology Flashcards

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