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| + | == Introduction<br> == |
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| | + | Left ventricular concentric hypertrophy without an identifiable cause is known as hypertrophic cardiomyopathy. The ventricular myocardium becomes so thick that the lumen is reduced to a size that is not compatible with maintaining the heart's function as a pump. The left ventricle no longer has the capacity to hold normal volumes of blood during diastole. As a result, the left atrium dilates from the increased pressure and volume of blood backing up into the lungs. |
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| − | *Rare in dogs
| + | This heart disease is rare in dogs but is the most common cardiac disease in cats. It more frequently occurs in persians and siamese breeds of cat. It is thought to be inherited in Maine Coon cats.<br> |
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| − | *Common in cats
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| − | [[Image:hypertrophic cardiomyopathy.jpg|right|thumb|125px|<small><center>'''Hypertrophic cardiomyopathy (cat)'''. Courtesy of T. Scase</center></small>]]
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| − | [[Image:hypertrophic cardiomyopathy 2.jpg|right|thumb|125px|<small><center>'''Hypertrophic cardiomyopathy (cat)'''. Courtesy of T. Scase</center></small>]]
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| − | ===Signalment=== | + | == Clinical Signs<br> == |
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| − | Dogs: Rare
| + | The disease can often be prevalet but without clinical signs (asymptomatic). |
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| − | Cats: Pedigrees (e.g. Persians, Maine Coons) & mixed breeds; Occurs in young pedigrees and young to old mixed breeds; Male>Female
| + | There may be hindlimb paresis or weakness, if saddle thrombus (cats) occurs due to this disease.<br> |
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| | + | There will usually be signs of left-sided heart failure.Tachycardia, arrhythmias and dyspnoea can also be seen.<br> |
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| − | ===Description===
| + | <br> |
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| − | *Left ventricular concentric hypertrophy without an identifiable cause is known as hypertrophic cardiomyopathy. The ventricular myocardium becomes so thick that the lumen is reduced to a size that is not compatible with maintaining the heart's function as a pump. The left ventricle no longer has the capacity to hold normal volumes of blood during diastole. As a result, the left atrium dilates from the increased pressure and volume of blood backing up into the lungs.
| + | == Diagnosis<br> == |
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| | + | Physical examination and auscultation will reveal a systolic murmurand ventricular arrhythmias. <br> |
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| − | ===Diagnosis===
| + | Radiography of the thorax will show a degree of left atrial enlargement, a generally enlarged heart and pulmonary congestion & edema. <br> |
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| − | ====History & Clinical Signs====
| + | On Electrocardiography (ECG), there will often be presence of a tall R wave and a wide QRS complex. Ventricular arrhythmias, conduction disturbances and sinus tachycardia may also be seen.<br> |
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| − | -Asymptomatic
| + | Upon Echocardiography, left ventricular concentric hypertrophy, left atrial enlargement and mitral valve insufficiency are commonly seen with this condition. The chamber size will appear dramatically reduced.<br> |
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| − | -Hindlimb paresis or weakness (saddle thrombus see in cats)
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| − | -Signs of left-sided heart failure
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| | + | == Treatment == |
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| | + | It is necessary to treat the individual symptoms, as there is no treatment for the condition. |
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| − | ====Physical Exam:====
| + | Drugs with contraindications include arterial vasodilators and positive inotropes. |
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| − | -Systolic murmur
| + | <br> |
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| − | -Ventricular arrhythmias
| + | == Prognosis == |
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| | + | Poor for symptomatic cats |
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| − | ===Radiography===
| + | <br> |
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| − | -Left atrial enlargement
| + | == References<br> == |
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| − | -Enlarged heart
| + | Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company<br>Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)W.B. Saunders Company<br>Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier <br> |
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| − | -Pulmonary congestion & edema
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| − | ===Electrocardiography (ECG)==== | + | == Test yourself with the Myocardial Pathology Flashcards == |
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| − | -Tall R wave
| + | [[Myocardial Pathology Flashcards]] |
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| − | -Wide QRS
| + | [[Category:Cardiomyopathy]] [[Category:To_Do_-_Review]] |
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| − | -Ventricular arrhythmias
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| − | -Conduction disturbances
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| − | -Sinus tachycardia
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| − | ====Echocardiography====
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| − | -Left ventricular concentric hypertrophy
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| − | -Left atrial enlargement
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| − | -Mitral valve insufficiency
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| − | ===Treatment===
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| − | -Treat the individual symptoms
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| − | Contraindications: Arterial Vasodilators; Positive Inotrops
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| − | ===Prognosis===
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| − | -Poor for symptomatic cats
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| − | ==From Pathology==
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| − | [[Image:hypertrophic cardiomyopathy.jpg|right|thumb|125px|<small><center>'''Hypertrophic cardiomyopathy (cat)'''. Courtesy of T. Scase</center></small>]]
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| − | ''Incidence:''
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| − | The cat is most commonly affected.
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| − | There is some evidence of inheritance, as in man, and the disease is said to be more common in male cats. There is a wide age range of 7 months to 24 years.
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| − | Inherited in Maine Coon cats.
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| − | ''Clinical signs:''
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| − | Grossly there is disproportionate hypertrophy of the left ventricle and often the interventricular septum. The chamber size is dramatically reduced.
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| − | Histologically there is haphazard hypertrophy of the myocardial fibres.
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| − | The reduction in left ventricular volume and the stiffened ventricular wall results in diastolic dysfunction, the stroke volume is reduced resulting in congestive heart failure and the following clinical signs:
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| − | [[Image:hypertrophic cardiomyopathy 2.jpg|right|thumb|125px|<small><center>'''Hypertrophic cardiomyopathy (cat)'''. Courtesy of T. Scase</center></small>]]
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| − | *Tachycardia.
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| − | *Arrhythmia (abnormal myocardium)
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| − | *Dyspnoea.
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| − | The force of the left ventricular contraction reduces afterload and reduces end-systolic volume to zero in some cases. This is '''cavity obliteration'''.
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| − | *[[Atrial_Thrombosis|Thromboembolic disease]] is a frequent complication. The thromboemboli most often impact in the femoral arteries manifesting as an acute hindlimb paralysis.
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| − | ====Feline Hyperthyroidism====
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| − | A hypertrophic cardiomyopathy is seen secondary to this disease in elderly cats. Thyroid hormones induce the growth of the myocardium.
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| − | ==Test yourself with the Myocardial Pathology Flashcards==
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| − | [[Myocardial Pathology Flashcards]]
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| − | [[Category:Cardiomyopathy]][[Category:To_Do_-_Cardiovascular]] | |