Difference between revisions of "Degenerative Mitral Valve Disease"

From WikiVet English
Jump to navigation Jump to search
Line 7: Line 7:
 
*Rare in other species  
 
*Rare in other species  
  
===Signalment===
+
==Signalment==
  
 
Typically in middle aged to older small breed dogs. Genetically predisposed breeds include Cavalier King Charles Spaniel, Bull Terriers, German Shepherds, and Great Danes.
 
Typically in middle aged to older small breed dogs. Genetically predisposed breeds include Cavalier King Charles Spaniel, Bull Terriers, German Shepherds, and Great Danes.
  
===Introduction===
+
==Introduction==
 
A congenital malformation or degeneration of the mitral valve leaflets and its supporting structures(chordae tendineae, papillary muscles, valvular leaflets, annulus) results in valvular regurgitation (insufficiency)  
 
A congenital malformation or degeneration of the mitral valve leaflets and its supporting structures(chordae tendineae, papillary muscles, valvular leaflets, annulus) results in valvular regurgitation (insufficiency)  
  
 
Chronic mitral regurgitation leads to volume overload of the left heart, which results in dilatation (eccentric hypertrophy) of the left ventricle and atrium. When mitral regurgitation is severe, cardiac output decreases, which results in signs of left sided cardiac failure [[LCHF]] and pulmonary venous congestion. Dilatation of the left-sided chambers predisposes affected animals to [[arrhythmias]]. In some cases, malformation of the mitral valve complex causes a degree of valvular stenosis as well as insufficiency.
 
Chronic mitral regurgitation leads to volume overload of the left heart, which results in dilatation (eccentric hypertrophy) of the left ventricle and atrium. When mitral regurgitation is severe, cardiac output decreases, which results in signs of left sided cardiac failure [[LCHF]] and pulmonary venous congestion. Dilatation of the left-sided chambers predisposes affected animals to [[arrhythmias]]. In some cases, malformation of the mitral valve complex causes a degree of valvular stenosis as well as insufficiency.
 +
In advanced cases, signs of right sided congestive heart failure may follow dur to an increased pressure load on the right ventricle as a result of long standing pulmonary congestion.
  
===Diagnosis===
+
==Diagnosis==
 
===History===
 
===History===
 
*Exercise Intolerance
 
*Exercise Intolerance
 
*Cough  
 
*Cough  
 
* Dyspnoea
 
* Dyspnoea
*Suden death due to left atrial tear and pulmonary oedema
+
*Sudden death due to left atrial tear and pulmonary oedema
 
===Clinical Signs===
 
===Clinical Signs===
 
* Left apical Systollic Murmur
 
* Left apical Systollic Murmur
 
* Left sided Congestive heart failure
 
* Left sided Congestive heart failure
 +
**Resting Tacchycardia
 
**Pale Mucous membranes
 
**Pale Mucous membranes
 
** Prolonged Capillary refill time (CRT)
 
** Prolonged Capillary refill time (CRT)
Line 30: Line 32:
 
** Pulmonary crackles / evidence of pulmonary oedema
 
** Pulmonary crackles / evidence of pulmonary oedema
 
** Cool extremities
 
** Cool extremities
** Loss of sinus tacchycardia
+
** Loss of sinus arrhythmia
 
** Cardiac arrhythmias e.g. Atrial fibrilation, Atrial premature complexes
 
** Cardiac arrhythmias e.g. Atrial fibrilation, Atrial premature complexes
 
===Diagnostic imaging===
 
===Diagnostic imaging===
Line 38: Line 40:
 
* Pulmonary Oedema
 
* Pulmonary Oedema
 
Evidence of Right sided congestive heart failure maybe evident in severe cases e.g. distended caudal vena cava, hepatomegaly, ascites, pleural effusions.  
 
Evidence of Right sided congestive heart failure maybe evident in severe cases e.g. distended caudal vena cava, hepatomegaly, ascites, pleural effusions.  
 +
====Echocardiography====
 +
*Left Atrial enlargement
 +
*Left Ventricular Enlargement
 +
* Increased Fractional Shortening ( The % change in the left venticular diameter during systole  used as a measure of systollic function)
 +
*Malformed Valve leaflets
 +
*Evidence of the regurgitant jet and turbulent flow in colour dopler
 +
===Electrocardiogram===
 +
* Enlarged Left Atrium (Wide P Wave)
 +
*Enlarged Left Ventricle (Tall R wave, wide QRS complex, shift of mean electrical axis to the left)
 
===Laboratory Tests===
 
===Laboratory Tests===
  
---
+
==Treatment==
Mild defects may be asymptomatic
+
==Prognosis==
 +
==Literature Search==
 +
==References==
  
Signs of left sided congestive (dilated) heart failure:
+
-----
 
 
-Cough
 
 
 
-Tachypnea/Dyspnea
 
 
 
-Exercise Intolerance
 
 
 
-Syncope
 
 
 
-Pale Mucous Membranes
 
 
 
-Tachycardia
 
 
 
-Arrhythmias
 
 
 
====Physical Exam====
 
 
 
-Left apical systolic murmur
 
 
 
-Left diastolic murmur
 
 
 
-Poor pulses
 
 
 
====Radiographic Findings====
 
 
 
-Left atrial enlargement
 
 
 
-Left ventricular enlargement
 
 
 
-Enlargement of pulmonary veins
 
 
 
-Pulmonary edema
 
 
 
====Echocardiographic Findings====
 
 
 
-Left atrial enlargement
 
 
 
-Left ventricular enlargement
 
 
 
-Malformed valve leaflets
 
 
 
Doppler can detect mitral stenosis or regurgitation and estimate pressures in the left atrium and pulmonary veins
 
 
 
====Electrocardiographic (ECG)====
 
 
 
-May be normal
 
 
 
-Signs of left atrial (wide P waves)
 
 
 
-Signs of left ventricular (tall R waves)
 
 
 
-Signs of arrhythmias
 
 
 
===Treatment===
 
 
 
Control left atrial pressure and manage left sided congestive heart failure
 
 
 
'''Goal of treatment for congestive heart failure:'''
 
 
 
-Diuretics (decrease venous congestion)
 
 
 
-ACE-inhibitors; Vasodilators (inhibit water retention and dilate the vessels)
 
 
 
-Anti-coagulants (cats) to prevent thrombus formation
 
 
 
===Prognosis===
 
 
 
'''Mild Defects'''
 
 
 
-Excellent
 
 
 
'''Severe Defects'''
 
 
 
-Guarded
 
  
 
==From Pathology==
 
==From Pathology==

Revision as of 19:17, 15 November 2010




Also known as: MVD, Mitral insufficiency, Mitral endocardiosis, Myxomatous Mitral Valve Disease (MMVD)

  • Common in dogs and cats
  • Rare in other species

Signalment

Typically in middle aged to older small breed dogs. Genetically predisposed breeds include Cavalier King Charles Spaniel, Bull Terriers, German Shepherds, and Great Danes.

Introduction

A congenital malformation or degeneration of the mitral valve leaflets and its supporting structures(chordae tendineae, papillary muscles, valvular leaflets, annulus) results in valvular regurgitation (insufficiency)

Chronic mitral regurgitation leads to volume overload of the left heart, which results in dilatation (eccentric hypertrophy) of the left ventricle and atrium. When mitral regurgitation is severe, cardiac output decreases, which results in signs of left sided cardiac failure LCHF and pulmonary venous congestion. Dilatation of the left-sided chambers predisposes affected animals to arrhythmias. In some cases, malformation of the mitral valve complex causes a degree of valvular stenosis as well as insufficiency. In advanced cases, signs of right sided congestive heart failure may follow dur to an increased pressure load on the right ventricle as a result of long standing pulmonary congestion.

Diagnosis

History

  • Exercise Intolerance
  • Cough
  • Dyspnoea
  • Sudden death due to left atrial tear and pulmonary oedema

Clinical Signs

  • Left apical Systollic Murmur
  • Left sided Congestive heart failure
    • Resting Tacchycardia
    • Pale Mucous membranes
    • Prolonged Capillary refill time (CRT)
    • Prolonged Jugular filling time
    • Pulmonary crackles / evidence of pulmonary oedema
    • Cool extremities
    • Loss of sinus arrhythmia
    • Cardiac arrhythmias e.g. Atrial fibrilation, Atrial premature complexes

Diagnostic imaging

Radiography

  • Cardiomegaly with dirsal displacement of the trachea
  • Pulmonary Venous Congestion (Enlarged pulmonary Arteries and Veins)
  • Pulmonary Oedema

Evidence of Right sided congestive heart failure maybe evident in severe cases e.g. distended caudal vena cava, hepatomegaly, ascites, pleural effusions.

Echocardiography

  • Left Atrial enlargement
  • Left Ventricular Enlargement
  • Increased Fractional Shortening ( The % change in the left venticular diameter during systole used as a measure of systollic function)
  • Malformed Valve leaflets
  • Evidence of the regurgitant jet and turbulent flow in colour dopler

Electrocardiogram

  • Enlarged Left Atrium (Wide P Wave)
  • Enlarged Left Ventricle (Tall R wave, wide QRS complex, shift of mean electrical axis to the left)

Laboratory Tests

Treatment

Prognosis

Literature Search

References


From Pathology

Often associated with mitral regurgitation and left atrial volume overload. Usually progresses to left sided heart failure.

Incidence:

Mitral dyplasia. Courtesy of A. Jefferies
  • Most common congenital defect in cats.
  • Also reported in pure breed dogs E.g GSD, Great Danes.

Clinical Signs:

  • Often murmur is the only clinical sign; pansystolic with increased intensity over the mitral valve area.
  • May also see exercise intolerance, dyspnoea and coughing.

Diagnosis:

  • Left atrial enlargement on radiology and ECG.
  • Doppler echocardiography can dtect abnormal flow.

Treatment:

  • Prognosis poor, medically manage left heart failure with ACE-inhibitors etc.