Transcript DCM - EIWC
DCM • • • • • • • • Clinical examination Auscultation Radiology Ultrasound examination ECG Laboratory tests Genetic testing Blood pressure measurement Grade 1 weak murmur requiring careful auscultation Grade 2 weak murmur that can be heard immediately Grade 3 moderate murmur Grade 4 strong murmur without thrill Grade 5 strong murmur with thrill Grade 6 murmur can be heard without stethoscope Lateral projection VD projection Dilatation and kongestion lat Dilatation and kongestion VD DCM The most common cardiac disease in the large and giant breed dogs The disease has a long preclinical period lasting from 1-4 years Congestive heart failure develops at the later stages of the disease Disease is more common in male dogs DCM is a primary form of myocardial disease leading to impaired cardiac contractility and cardiac dilatation To compensate the reduced contractility the heart enlarges and the heart rate often increases Arrhytmias are common, most often dogs develop atrial fibrillation or ventricular premature complexes The cause of the disease is not verified but genetic predisposition is obvious Symptoms often start suddenly without earlier signs of the disease Sudden cardiac death may be caused by arrhytmias Prevalent opinion is that DCM is a group of diseases with genetic predisposition For this reason there are significant differences in clinical outcome between different breeds First genetic tests are available Ultrasound examination can be used to seek for preclinical cases At least the following breeds are at increased risk Doberman pincher, boxer, Finnish hound, Great dane, Irish wolfhound, Newfoundland, St. Bernard, cockerspaniel, English springerspaniel, Islandic sheepdog, Portuguese Water Dog, Dalmatian Autosomal dominant – boxer and Doberman pincher Great Dane – not known Irish Wolfhound –combined monogenic/polygenic inheritance Genetic mutation has so far been found in Doberman ja boxer breeds Two different forms has been found In doberman pincher and boxer fatty infiltrates develop in the heart muscle cells (fatty infiltrate) This form of the disease seems to be clinically more severe Giant breed dogs seem to have so called wavy fiber form of the disease Is the mode of inheritance same? Irish wolfhounds seem to have a mutation that affects lipid metabolism of the heart muscle cells Impaired cardiac contractility may be caused by noncardiac disease Most common causes of secondary cardiomyopathy are hypothyroid disease, myocarditis and tumors Fs value often decreases between 20-25 %, rarely below 20 % Chocolate poisoning Adriamycin (chemotherapy) Prolonged tachycardia Increased blood pressure? Cough Respiratory distress Exercise intolerance Nightly restlessness Ascites Loss of weight Reduced apetite Syncophy Very common Very common Very common Common Common Common Rare Rare Auscultation may be normal Murmur or arrhytmia may be heard Rtg finding may be normal at the early stages Rtg findings are not spesific Ultrasound examination is needed to confirm the diagnosis Preclinical stage may be challenging Cardiac neurohormones Holter monitoring How many VPC:s is abnormal? Boxer over 100/24 hours is suspicious Doberman – yli 50/24 hours suspicious, over 100/24 hours abnormal Normal Fs Reduced Fs • • • • • • • Pimobendane 0,1-0,3 mg/kg bid Furosemide 0,5-3 mg/kg sid-tid ACE inhibitor Digitalis 0,005-0,01 mg/kg bid Spironolaktone 1-2 mg/kg sid-bid Hydrochlorotiatside 2-4 mg/kg bid L-karnitine 1-2 g/dog bid-tid, taurin 500 mg/dog bid Normal rhytmm Sinustachycardia AF with slow ventricular rate AF with rapid ventricular rate Digoxin 0,005-0,01 mg/kg bid Sotalol 1-2 mg/kg bid Atenolol 6,25-25 mg bid Propranolol 0,2-2 mg/kg tid Diltiazem 0,5-2 mg/kg tid Digoxin may be combined with either betablocker or calsium channel blocker When to treat? Sotalol 1-2 mg/kg bid Atenolol 6,25-25mg bid Propranolol 0,2-2 mg/kg tid Diltiazem 0,5-3 mg/kg tid No treatment unless heart rate is elevated Tachycardia as atrial fibrillation Lidocaine iv 2 mg/kg slow bolus No more than 8 mg/kg (4 boluses) Continued 40-100 g/kg/min Sotalol 1-22 mg/kg bid Atenolol 6,25-25 mg bid Mexiletine About 20 % of Irish Wolfhounds develop dilated cardiomyopathy at some point of their life Mean age of onset is 4,5 years Most dogs develop the disease between 3-7 years of age Male dogs have significantly higher risk than females Most affected dogs have concurrent atrial fibrillation which may be a first sign of the disease The left ventricular function does not often become severely compromised until the later stages of the disease, which improves the survival time Survival time may be longer than in many other breeds Some dogs developing the disease at middle age may survive to old age A dog may still die of sudden cardiac death DCM is in any case a major cause of death in this breed Fs below 25 % End diastolic diameter over 61 mm End systolic diameter over 41 mm EF measured by Simpsons method below 45 % Atrial fibrillation diagnosed by ECG Two studies trying to establish a mode of inheritance for DCM in IWH has been published 2007 and 2012 Both groups published similar conclusions In both studies a simple dominant monogenic mode of inheritance coud be rejected The model that best explained the results was a mixed monogenic-polygenic model with an autosomal dominant sex dependant major gene and further polygenic effects 5 minor loci associated with development of DCM coud be identified A most propable mode of inheritance in IWH is a model where one dominant major gene needs futher polygenic effects for the disease to develop The major gene is located on CFA37 Its gene action is significantly different between male and female dogs The major risk allele is a common variant widely spread in the population Detected genes affect lipid metabolism Cells in the heart muscle use lipids as they energy source Impaired cardiac function seems to be the result of increased lipid production in the heart muscle cells In the last three years I have performed a cardiac examination for 45 individual Irish Wolfhounds 9 of these dogs have so far been assessed to have DCM Only three of these dogs show a typical mode of the disease with impaired cardiac function and cardiac dilatation On the other dogs diagnosis is based on development of arrhytmias The dogs have acguired atrial fibrillation with of without VPC:s Five of these dogs are on medication either because of congestive heart failure or atrial fibrillation with rapid ventricular rate Three dogs have been assessed as equivocal They have arrhytmias that are not severe enough to establish a diagnosis of DCM One dog has been diagnosed a mitral regurgitation Findings are consistent with other similar studies Results send to the Irish wolfhound association show lesser incidense This is because of three reasons Some of the dogs have been so young when examined that the disease may not yet be detectable Many dogs are female with a smaller risk Dogs assessed equivocal having atrial fibrillation shoud be assessed DCM Examining dogs below the age of three is not effective Ultrasound examination does not find all cases before dogs are used for breeding ECG examination shoud always be performed together with ultrasound Holter monitoring ? Genetic testing is not yet available for IWH Cardiac biomarkers are not sensitive enough to recognize the disease in early stages Available method is ultrasound examination combined with ECG and possibly Holter monitoring Hopes were these woud prove to be an easy method to recognise cardiac disease at early stages Blood sampling does not require the expertese needed to perform cardiac ultrasound or ECG Troponine is released in conjuction with sudden cardiac injury It can be measured in the blood sample Unfortunately the halflife of troponine is short and its release is not spesific for particular cardiac disease High sensitive troponine is elevated for some months Lack of specifity makes troponine unsuitable for breeding examinations Elevated value indicates cardiac injury Brain natriuretic peptide Is released almost entirely from heart muscle cells Overlap between individuals is too wide to make BNP suitable for detecting the early disease BNP is suitable for assessing the progression of the heart disease, increasing value indicates the increase in severity Simpler test methods have been developed