Trying to understand Dilated Cardiomyopathy & What to do to try and hold off heart failure and/or sudden death.
Echocardiogram & Holter TestIt seems the holter picks up symptoms before they are visable on the echo. Dobermans should be screened with a 24 hour Holter. A ECG trace tracks less than 10 minutes in time. Evidence of ventricular arrhythmia precedes echocardiographic evidence of DCM in the Doberman by some months or even years*1.
Ventricular triplet: Three consecutive premature ventricular contractions.
Complex PVCs: *3
- occur in pairs, triplets or more prolonged runs of ventricular tachycardia.
- Fall in the vulnerable period of the cardiac cycle (R on T).
- Have more than one morphology.
Patients with three or more consecutive premature ventricular contractions in a row have ventricular tachycardia. Ventricular tachycardia that is prolonged can result in low cardiac output, low blood pressure, and fainting (syncope). Ventricular tachycardia can also develop into ventricular fibrillation, which is a fatal heart rhythm (see below).
Ok, so you what if the Echocardiogram is clear, but the Holter shows these PVCs, what do you do?Most cardiologist will suggest antiarrhythmic therapy once an arrhythmia, such as atrial fibrillation or ventricular tachycardia, is discovered.
In Doberman pinschers, ventricular tachyarrhythmias are common although atrial fibrillation is also often present.
Atrial fibrillation, therapy is usually aimed at reducing ventricular rate by introducing digoxin, or a beta-blocker carvedilol, metoprolol, atenolol, or propranolol.
Ventricular tachycardia, therapy commonly uses antiarrhythmics include sotalol, amiodarone; should be used with caution due to irreversible hepatoxicity), or a combination between mexiletine and a low dose atenolol. A significant (85%) reduction of number of ventricular complexes is considered a therapeutic success.
Ventricular tachycardia: This rhythm is diagnosed when three or more premature ventricular complexes occur in a row at a rate of 100-120 beats per minute or faster.
Carvedilol is a beta blocker than has been doing wonders with humans with DCM. Carvedilol is a non select beta and alpha blocker that has oxygen radical scavenging capabilities and reduces endothelin release. The drug in addition to sparing the heart the effects of the sympathetic nervous system, it is a vasodilator and antioxidant. It will reduce the heart rate a little which I have to keep an eye on. Khep's heart rate prior to his throid meds was already low (70bmp resting), but that was seen normal because he is physically fit. After getting his hypothyroid undcontrol, his average is now aroun 84 bmp resting. Carvedilol has some antiarrhythmic properties too because it improves how the heart functions, hopefully it will have Khep's heart pumping more efficient, which will discourage the left ventricle to increase. This prolongs the onset of DCM = longer life :)
Dogs must be brough on Carvedilol very slowly, and keep an eye on their heart rate and daily activity levels. After slowing increasing over two+ months many dogs will tolerating 25mg twice a day! Chances of holding off heart enlargement will be better. Another echo should be scheduled in 6 months.
With the Walgreens RX plan, the full dose only cost $10/month instead of $193!!!
Doberman's have a high chance of having thyroid issues! Have a full thyroid panel done too!Hypothyroidism can lead to contraction problems with the heart. This can make heart failure advance much faster. It can also effect the electrical currents in the heart and cause an arrhythmia. All things a Dobe don't need. Many Dobes have this problem, it is 90% genetic. When dealing with the heart it is important to have this checked out.
Heart Healthy Diet & Supplements
Another Echocardiogram & Holter Test, Dilated Cardiomyopathy may have advanced (;_;)After a period of time (3 months to 24 months) the left ventrical usually begins to show signs of enlargement, and the heart wall muscle does not contract as well.
Check ups are often 6 months apart.
In Doberman pinschers with DCM, ventricular arrhythmias are a consistent finding on 24-hour ECG (Holter) recordings. Doberman pinschers with echocardiographic evidence of the disease almost always have more than 50 premature ventricular depolarizations on a Holter recording. The number of premature depolarizations and the complexity of the premature depolarizations increases as the disease progresses. Doberman pinschers with ventricular tachyarrhythmias are at increased risk of sudden death. *2
In dogs with cardiac dilatation, ACE-inhibitors and/or the inodilator pimobendan (0.25 mg) are often introduced.
If the echo just shows the left ventrical beginning to enlarge and the decesae in heart fuction, it is DCM, but still at the earily stages. Pimobendan may be be able to help hold CHF back.
PimobendanPimobendan, a newer phosphodiesterase 3 inhibiting inotrope, better termed an inodilator (inotrope and mixed vasodilator), has shown significant promise in the management of dilated cardiomyopathy and probably mitral regurgitation. This drug, currently being used widely at 0.2-0.6 mg/kg divided BID (given 1 hour before feeding) in Europe and Australia, is thought to work, in part, by sensitizing the troponin C complex to calcium. The aforementioned association between postive inotropes and sudden death has not been recognized with pimobendan, reputedly because there is less or no increase in intracellular calcium and because of its arteriolar dilating capacity, which unloads the ventricles. A prospective study by Fuentes, et al. demonstrated improved survival in Doberman pinschers with dilated cardiomyopathy and the PiTCH study prospectively showed improved clinical outcomes in dogs with DCM and mitral regurgitation, as compared with ACE-Inhibition. A retrospective study, comparing pimobendan to historical controls treated standardly, by Gordon and colleagues in dogs with mitral regurgitation showed improved survival, vertebral heart score, heart and respiratory rate, and left atrial size, without evidence of arrhythmogenesis.
Diminished contractility :: Pimobendan 0.25 mg/kg b.i.d. PO
Sudden Death - if you do testing, you will have some warningThe idea of sudden death really scared me. After reading a little more, I learned that sudden death occurs when the PVCs become frequent and progress to ventricle fibrillations. Another form of PVCs that can be rapid and sustained is called Ventricular Tachycardia (VT). They can also switch over to ventricle fibrillations. It is these heart arrhythmias that usually cause sudden death. the heart beats so fast, blood can not circulate oxygen properly and the dog will pass out. If the heart does not adjust itself, the dog will die with a minute or so.
VT's are caused by heart failure. The echocardiogram should begin to pick up enlargement, as the heart fails, VT's may become more common. There are some drugs out there to help control the heart rhythm. If the dog has episodes of passing out, they are usually used. Some drugs will make the heart failure worse in some dogs, it depends on the dogs. Make sure you are comfortable with your vet and just keep an eye on the test.
*1 - http://ecihealthreport.blogspot.com/2008/11/dilated-cardiomyopathy-in-dogs.html
*2 - http://www.vmth.ucdavis.edu/cardio/cases/case2/text.htm
*3 - http://www.americanheart.org/presenter.jhtml?identifier=565
**** I'm not a vet or even close to an expert on this. I've just spent a lot of time reading online trying to figure out what I can do for my boy. Above is the best information I could find. If you have any questions, feel free to contact me at web@DobermanData.com
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