Canine Cardiomyopathies (Borgarelli) Flashcards
DCM is decreased ____ due to a dysfunction of ____.
DCM is decreased __contractility__ due to a dysfunction of __systole__
Difference b/w concentric and eccentric cardiac hypertrophy
Concentric hypertrophy: due to increased LV wall thickness
Eccentric hypertrophy: due to LV dilation
DCM pathophysiology (4)
Primary systolic dysfunction –> Secondary eccentric hypertrophy –> Tertiary mitral regurgitation –> Quaternary atrial enlargement
Why do some dobermans with pre-clinical DCM die suddenly?
They have developed a ventricular arrhythmia:
> 3 consecutive VPCs => Vtach => Vfib (fatal)
VPCs may occur in rapid succession => Vtach. Vtach may lead to a decrease in blood flow to the body, and when perfusion to the brain decreases enough dogs may collapse. Vtach may degenerate into ventricular fibrillation which is a fatal abnormal rhythm.
Use of a Holter monitor / why
Used in pre-clinical DCM screening, usually preceding echo findings.
Allows for 24-hour ECG recording, which can better pick up infrequent VPCs
Singular VPCs are considered abnormal if there > 50 to 100 of them recorded during a 24 hour holter monitor study.
The risk for sudden death from erratic ventricular heart beats increases as the numbers of couplets, triplets or runs of ventricular tachycardia increase on a 24 hour holter study. These abnormal heart beats may be sustained and occur at rates that are so fast that the pumping of the heart is ineffective and oxygen is not carried to the dogs brain adequately. When this occurs the dog will faint or experience syncope, when he exerts. If the abnormally fast heart beats slow down, the dog will wake up or experience aborted sudden death. If the fast and abnormal rhythm continues for just a few minutes continuously, the dog will die.
Importance of a pre-clinical DCM diagnosis (3)
- allows for early treatment/therapy
- knowledge that the pt is at an increased risk for anesthesia
- allows for screening of the gene for breeders
What makes an animal with pre-clinical DCM more at-risk for anesthesia?
While under anesthesia, the pre-clinical DCM pt. will be at an…
1. increased risk for arrhythmia exacerbation
2. increased risk for declining systolic function
What have studies shown to be the effects of dogs with pre-clinical DCM treated with Pimobendan versus Benazepril (ACE-inhibitor)?
Both significantly increased median time to onset of overt DCM (CHF or sudden death) and therefore can extend survival times.
Why do dogs with pre-clinical DCM require serial echocardiographic exams?
B/c DCM is a progressive disease (can significantly increase in severity in one year)
Common clinical signs of dogs with DCM (4)
- syncope
- tachypnea (rapid RR) / polypnea (very frequent shallow breathing)
- weight loss
- exercise intolerance
What sign is indicative that a dog is in bilateral CHF for DCM?
presence of abdominal distention (ascites)
Why must radiographs be performed in all dogs presenting with clinical DCM?
To determine if they have CHF
- left-sided/generalized cardiomegaly
- pulmonary edema
- +/- pulmonary effusion
What 2 other conditions present as a hypokinetic (decreased LV RoM) on echo in addition to DCM?
- Tachycardia-Induced Cardiomyopathy
- Subaortic Stenosis (end-stage)
Arrhythmogenic Right Ventricular Cardiomyopathy // Boxer Cardiomyopathy:
A genetic / boxer-specific disease where a fatty or fatty/fibrous infiltration replaces RV myocardium (due to desmosome abnormality)
3 categories of boxer cardiomyopathy
- No clinical signs or arrhythmias
- Syncope or weakness + arrhythmias (VPCs)
- Heart failure and arrhythmias
