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Degenerative Mitral Valve Disease (view source)
Revision as of 14:16, 11 May 2021
, 14:16, 11 May 2021Addition in clinical signs, diagnostics and treatment
In cases where DMVD becomes clinically significant, a '''cough''' is usually the first clinical sign noticed by the owner. The coughing is likely of multifactorial aetiology and may be related to pulmonary oedema, stimulation of the juxtapulmonary (J) receptors that are associated with pulmonary capillaries and detect increases in pulmonary venous pressure, compression of a mainstem bronchi by an enlarged left atrium and concurrent airway disease. Occasionally, '''syncope''' is the first sign of clinically significant DMVD. This may occur due to arrhythmias or on exertion where mitral regurgitation limits stroke volume and therefore cardiac output.
In cases where DMVD becomes clinically significant, a '''cough''' is usually the first clinical sign noticed by the owner. The coughing is likely of multifactorial aetiology and may be related to pulmonary oedema, stimulation of the juxtapulmonary (J) receptors that are associated with pulmonary capillaries and detect increases in pulmonary venous pressure, compression of a mainstem bronchi by an enlarged left atrium and concurrent airway disease. Occasionally, '''syncope''' is the first sign of clinically significant DMVD. This may occur due to arrhythmias or on exertion where mitral regurgitation limits stroke volume and therefore cardiac output.
Other symptoms that may occur include increased exercise intolerance and efficiency, tachypnea or dyspnea during exercise, ascites, weight loss, anorexia and thromboembolisms.
== Diagnosis==
== Diagnosis==
* P-mitrale: wide P waves in leads II, III and aVF, indicates left atrial enlargement
* P-mitrale: wide P waves in leads II, III and aVF, indicates left atrial enlargement
* high R-wave
* Stage C2-D: (supra-) ventricular extrasystoles
===Laboratory Tests===
===Laboratory Tests===
== Treatment ==
== Treatment ==
===Stage B===
===Stage B===
There is no evidence that any therapy slows the progression of asymptomatic disease.
There is no therapy demonstrated to be beneficial in dogs with stage B1 disease. Nevertheless the cardiac function should be controlled after 12 months or earlier if the general condition gets worse.
The results of the EPIC study demonstrated that administration of '''Pimobendan''' to dogs with stage B2 disease resulted in prolongation of the asymptomatic phase of disease by approximately 15 months. Dogs receiving Pimobendan were around 33% less likely to go into congestive heart failure or suffer a cardiac death than those not receiving the drug. Pimobendan appears safe and well-tolerated. The cardiac function should be controlled after 6-12 months.
Based on findings of the EPIC study, dogs with typical mitral valve murmurs of grade III/VI or higher should be investigated to look for evidence of cardiomegaly. If cardiomegaly is apparent, then the dog may benefit from starting Pimobendan, as opposed to the 'watch and wait' approach that was previously recommended.
===Stage C===
===Stage C===
Medical management is intended to alleviate clinical signs and prolong life.
Medical management is intended to alleviate clinical signs and prolong life.
Surgical mitral valve repair in dogs is currently being performed. However, availability is limited by the expense, required expertise and cardiopulmonary bypass facilities.
Surgical mitral valve repair in dogs is currently being performed. However, availability is limited by the expense, required expertise and cardiopulmonary bypass facilities.
If the patient shows supraventricular tachycardia '''Digoxin''' can be prescribed. If that does not work effectively '''calcium canal blockers''' can be added.
Relevant ventricular extrasystoles can be treated with '''sodium canal blockers.'''
Syncopes or acsites can be treated with '''Sildenafil.'''
'''Amlodipin''' can be used to treat systemic hypertension that occurs as a result to the valvular degeneration.
''<u>Clinical Example:</u>''
A patient is presented in an acute cardiac crisis. He is staged as C3-D. The therapy goal is to get him to C1.
# inpatient admission
# '''Furosemide'''
#* depending on the degree of severity: 2-4 mg/kg body weight, parenteral, every 2-6 hours
#* better is an intravenous drip that covers half of the conservation needs (1 mg/kg body weight per hour), can be reduced by half when the breathing rate has normalized
# '''Pimobendan'''
#* 0,15 mg/kg body weight once i.v.;
#* when the symptoms persist the injection can be repeated after 12 hours
# Oxygen
# thoracocentesis if there is a liquidothorax
# punction of the ascites if there is a right heart failure
# '''Dobutamin''': 5–10µg/kg body weight/min (Stadium D)
# '''Nitroglycerin''' with an atomizer: 1–2 pumps in the mouth (cave: do not breath in, wear gloves!)
# '''ACE inhibitors''' and '''Spironolactone''' should be added as soon as oral treatment is possible
'''''When the patient is stabilized:'''''
# treatment can be continued at home
# '''Sildenafil''' for the pulmonary hypertension
===Stage D===
===Stage D===
== Prognosis ==
== Prognosis ==
Asymptomatic patients may live for many years. Once heart failure occurs, life expectancy is usually around 6-12 months, although some patients remain stable for years. Risk factors for progression include severity of valvular lesions, increased age and male gender. Risk factors for onset of congestive heart failure include severity of mitral regurgitation, left atrial enlargement and elevated NT-proBNP. Development of complications such as atrial fibrillation or chordae tendinae rupture are associated with a poor prognosis.
Asymptomatic patients may live for many years. Dogs with stage B2 disease have a median of 27 months before developing congestive heart failure. Once heart failure occurs, life expectancy is usually around 6-12 months, although some patients remain stable for longer. Risk factors for progression include severity of valvular lesions, increased age and male gender. Risk factors for onset of congestive heart failure include severity of mitral regurgitation, left atrial enlargement and elevated NT-proBNP. Development of complications such as atrial fibrillation or chordae tendinae rupture are associated with a poor prognosis.
* Tilley,L.P., Smith, F.W.K, Oyama, M., Sleeper, M. (2016) '''Manual of Canine and Feline Cardiology (Fifth Edition)''' ''Saunders''.
* Tilley,L.P., Smith, F.W.K, Oyama, M., Sleeper, M. (2016) '''Manual of Canine and Feline Cardiology (Fifth Edition)''' ''Saunders''.
* Luis Fuentes, V, Johnson, L.R, Dennis, S. (2010) '''BSAVA Manual of Canine and Feline Cardiorespiratory Medicine (Second Edition)'''
* Luis Fuentes, V, Johnson, L.R, Dennis, S. (2010) '''BSAVA Manual of Canine and Feline Cardiorespiratory Medicine (Second Edition)'''
* Boswood, A. et al. Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study - A Randomized Clinical Trial. JVIM, September 2016. DOI: 10.1111/jvim.14586
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