Cardiology Flashcards
What do differing colours of mucous membranes signify?
Pink - good forward output
Pale - poor forward output/ anaemia
Yellow - pre/intra/post hepatic icterus, beware of artificial light
Cyanosis - respiratory compronise
Capillary refil time should be <2s - good forward output
What should you be examining in a cardio exam before you even touch the dog?
Demeanor, body ocndition, respiratory character - shallow eg pleural effusion, deep eg lower airway disease. Respiration rate - 15-30 minute in dogs, 15-40 min in cats. Resp rate is hypoxia driven.
What can you tell from the jugular vein in a cardiopulmonary exam?
Distension - after occlusion, right atrial pressures
Pulsation - tricuspid regurgitation, pericardial effusion, pulmonic stenosis, 3rd degree AV block
hepatojugular reflex - when you squeeze abdomen with ascites does the jugular bulge
What should you examine in the precordium?
Hands either side of cranial chest. Find apex beat on left side. Check heart rate, heart rhthmn, cardiac size, strength of apex beat, thrills from grade V or VI murmurs, check chest spring/compressibility.
What should you check for in the abdomen?
Distension, fluid thrill - ascites, hepatomegaly, splenomegaly,
What can you tell by taking the pulse?
Stroke volume, difference in systolic/diastolic, check femoral pulse, for pulse deficits, check both legs to see if symemtrical, check volume/strength, character.
What do different pulses signify?
Weak - poor output
Bounding - high output, elevated metabolic rate, pregnancy, pyrexia, anaemia, PDA, aortic insufficiency
Brief - sub aortic stenosis
Brisk - mitral regurgitation
What can you discover from checking the pulse?
Pulse deficits - arrythmia
Pulsus paradoxus - pericardial effusion - abnormally large decrease in systolic blood pressure during inspiration.
Pulsus alternans - myocardial failure - arterial pulse waveform showing alternating strong and weak beats. indicative of LV failure.
How do you auscultate the heart?
animal should be standing. pay attention to individual heart valves. Use mainly diaphragm. Listen to audibility, heart rate, rhythm, pulse deficits, murmurs, gallops: use bell of stethoscope.
What are the normal heart sounds?
AV valve closure - S1 LUB
S2 Dup - closure of aortic pulmonic valves - PMI left heart base
S3 - end of early ventricular filling
S4 - atrial contraction
What are the different types of murmur sounds?
Plateau, Crescendo-decrescendo Pancystolic Holosystolic Diastolic Continuous
What are the gradings Of murmurs?
Grade I - quiet difficult to hear with stethoscope
Grade II - VI - heard quickly but quieter than S1 and S2
Grade III - heard immediately, similar intensity to S1 and S2
Grade IV - louder than S1 and S2 but no precordial thrill
Grade V - precordial thrill but not heard if stethoscope lifted off chest wall
Gradee VI - precordial thrill and heard if stethoscope lifted off chest wall.
Describe different lung sounds that can be heard?
Normal breath sounds
Stertor (grunting - from nasal passages)
rhonchi - low frequency, fast airflow
Stridor - upper airway, laryngeal paralysis
Fine crackles - high frequency, alveolar fluid
Coarse crackles - low frequency, pulmonary fibrosis
Wheezes - higher frequency, narrow larger lower airways
Squeaks - highest frequency, narrow smaller airways.
What can you find out from percussing the thorax?
percussing assesses resonance. give a firm tap against middle finger. Dull over tissue - heart, consolidation lung, pleural effusion.
Resonant over air - normal lung, pneumothorax, pulmonary overinflation.
What is congestive heart failure?
Inability to meet the demand of the body, oxygen, Co2, exercise, rest. Congestion - venous congestion, high capillary pressures, high filling pressures. Oedema - increased tissue fluid formation, lymphatic drainage overwhelmed.
What are the presenting signs for CHF in dogs?
Coughing, breathlessness, abdominal distension - backward failure
Lethargy, excercise intolerance, syncope/collapse - forward failure.
Backward failure signs tend to proceed forward failure. Chronic coughing dogs tend to have more lethargy or excercise intolerance if the cough is due to cardiac disease. Cats with cardiac disease usually dont cough. Cats are either asymptomatic or dyspnoeic.
Why does backward failure precede forward failure?
Fall in blood pressure, detected by baroreceptors, message to brain, sympathetic nervous system activated, vasoconstriiction, increased heart rate, increased contraction, sympathetic nerous system damages heart.
What happens in chronic heart failure?
It is an alternative way of maintaining blood pressure. increased blood volume, activation of RAAS, activated by reduced renal filtration, activated by sympathetic nervous system, maintains blood pressure and cardiac outpu, counteracted by natriuretic peptides (atrial and ventricular stretch) ok for a while untill disease progresses, volume overload.
How can you treat backward heart failure?
Diuretic - furosemide, counteract RAAS with an ACE inhibitor, or aldosterone antagonist, improve cardiac output with a positive inotrope (ppimobendan)
What happens as CHF progresses?
Myocardial cell death, myocardial fibrosis, vasclar function reduced, cachexia, nitric oxide released, inflammatory cytokines TNFa, IL-1b, free radicals, necrosis, apoptosis, arrhythmias, myocardial remodelling
Describe heart failure in cats
Diastolic failure, poor filling of usually left ventricle, atrial enlargement, there is a need for preload. Cats get pleural effusion due to L CHF as well as pulmonary oedema. Treat with furosemide, ace inhibitors, anti thrombotic agents, aldoesterone antagonists, positive inotropes.
Name the key points of CHF
sympathetic tone is increased in CHF, dogs coughing due to CHF will usually have HR > 120 beats/min. Dogs coughing due to CHF will usually not have a sinus arrhythmia, feline CHF is not a true volume overload disease, medications don’t treat the underlying pathophysiology in cats as well as they do in dogs. Cats may need thoracocentesis with L CHF.
Which methods of investigation can you use in cardiac disease?
Signalment/history, physical examination, thoracic radiography, ECG/24 hour ECG/event recorder, blood tests, echocardiography, blood pressure, catheterisation studies, phonocardiography, post mortem.
What may the history be in cardiac failure?
Cough, dyspnoea, abdominal distension, Exercise intolerance/lethargy, syncope/collapse, inappetance, weight loss, stunting.
In canine cardiac cases commonly a cough is due to left atrial enlargement. Rare in cats with cardiac disease. Beware of concurrent cardiac & respiratory disease in dogs. Dyspnoea common in congestive heart failure in cats and dogs. Seen in left CHF due to pulmonary oedema. seen in right CHF due to pleural effusion. beware pleural effusion in cats due to left CHF. Exercise intolerance/lethargy - difficult to assess in cats, seen in many conditions affecting many systems. lethargy seen with severe CHF. Partial seizures may resemble syncope. Inappetanece more common in cats. Weight loss/cachexia - end stage CHF. Stunting - severe congenital disease.
What are common cardiac problems?
concurrent cardiac + respiratory - murmur + tracheal cllapse, murmur + asthma.
concurrent cardiac + endocrine/metabolic - aortic stenosis + insulinoma, DCM + hypothyroidism + laryngeal paralysis
What blood tests should be done for suspected cardiac failure?
Troponin-I, pro-BNP, hyperthyroidism, hypothryoidism, taurine deficiency, acromegaly, renal disease, hypadrenocorticism, insulinoma.
Which factors affect thoracic radiographic quality? What factors should you look at on the thoracic radiographs?
Phase of respiration, view, rotation, exposure factors, developing, obesity. Cardiac size, chamber size, great vessels, pulmonary vessels, lung pattern, pleural space changes.
What radiographic technique should be used in cardiac radiology?
Restraint for radiography is stressful for animals with minimal cardiac reserves. chemical restraint usually necessary but minimal doses should be used. to obtain good quality radiographs, the exposure time must be short. Best radiographs are obtained using low mAs, high kVP, use grid ( in large chests) only if short exposure time can be maintained. Dorso ventral and right lateral views should be obtained and accurate positioning is vital with minimum rotation.
What is the average cardiac size?
The length of the heart is measured on the lateral view against the number of vertebral bodies starting at the cranial edge of T4. the width of the heart is measured in vertebral bodies. The number of vertebral bodies from the length is added to the number of vertebral bodies from the width. The average number of vertebral bodies in dogs is 9.7 (8.5-10.5), and cats should not exceed 8 vertebral bodies. Cardiac size may also be evaluated using the number of intercostal spaces the heart occupies on the lateral view, 2.5-3.5 spaces is considered normal and the height should be less than 2/3rd o the height of the chest.
What is microcardia/cardiomegaly?
Microcardia is a decrease in cardiac size and is caused by hypovolaemia and hypoadrenocorticism. Cardiomegaly is an increase in cardiac size and generalised cardiomegaly is caused by pericardial effusion, peritoneo-pericardial diaphragmatic hernia and severe dilated cardiomyopathy.
Describe left atrial enlargement
Left atrial enlargement is one of the more reliable signs of cardiac disease. the angle between the terminal trachea and the caudal border of the heart becomes increasingly acute as the left atrium enlarges. the mainstem bronchi may become separated by a rounf soft tissue density on the DV view. A bulge caused by the left auricle may be evident at 2-3 oclock on the DV view. the cuadal vena cava may slope dorsally as it approaches the heart. left atrial enlargement is commonly seen with mitral insufficiency, dilated cariomyopathy, hypertrophic cardiomyopathy, patent ductus arteriosus.
Describe left ventricular enlargement
Left ventricular enlargement will result in straightening of the caudal border of the heart on the lateral view, and a rounding of the left border of the heart on the DV view at the 3-6 oclock position. there is often an increase in apico basilar length of the heart. in general if enlargement is due to dilatation then it is usually seen in association with left atrial enlargement. Left ventricular enlargement is commonly seen with mitral insufficiency, dilated cardiomyopathy, hypertrophic cariomyopathy, patent ductus arteriosus, ventricular septal defect.
Describe right atrial enlargement
Unless extreme, it appears as a cranial bulge on the lateral view. on the DV view a bulge may be seen in 9-11 oclock area. right atrial enlargement commonly seen with tricuspid insufficiency, pulmonic stenosis, dilated cardiomyopathy, restrictive/hypertrophic cardiomyopathy.
Describe right ventricular enlargement
Right ventricular enlargement results in increased sternal contact ont he lateral view and an increased rounding of the cardiac silhouette in the 6-9 oclock area on the DV view. right ventricular enlargement is commonly seen with tricuspic insufficiency, pulmonic stenosis, dilated cardiomyopathy, restrictive/hypertrophic cardiomyopathy.
Describe how the great vessels appear on cardiac radiology
Dilation of the aorta or pulmonary artery may occur due to turbulence frmo aortic or pulmonic stenosis, or from the patent ductus arteriosus. post stenotic dilation of the aorta may be visible as a prominent aortic arch on the lateral view, and as a bulge at the 12-1 oclock on the DV view. post stenotic dilation of the pulmonary artery may be seen as a bulge superimposed on the trachea on the lateral view and a bulge between 1-2 oclock on the DV. the caudal vena varies considerably in width with respiration but it may be persistently reduced in diameter in hypovolaemia or distended in right ventricular failure.
Describe the pulmonary vessels on radiography
The pulmonary vessels give an indication of the state of pulmonary circulation. the normal width of the cranial lobe vessels on a lateral view is approximately the with of the 4th rib, just below the spine. usually the arteries and veins are similar in diameter. with raised left atrial pressures, the pulmonary veins may be wider than the corresponding arteries. In over circulation of the lungs, such as with left to right shunts and fluid overload, the pulmonary arterteries and veins are both distended and prominent. vascular markings can also be seen extending further into the periphery than normal. in pulmonary arterial hypertension the pulmonary arteries may be wider than the veins.
What does pleural effusion appear like on radiography?
Pleural effusion are sen particularly in cats with heart failure but also in dogs. scalloping or leafing of the lung lobes is evident on the lateral view and soft tissue density interlobar fissures are evident on the DV. the cardiac silhouette is obscured.
What can electrocardiography measure?
Electrocardiography is very useful tool in the investigation of cardiac disease. It can provide information on: heat rate, rhythmn, chamber enlargement in small animals, electrolyte imbalance. twenty four hour recordings of heart rhythm using a holter monitor can provide very useful information in the investigation of collapsing or excercise intolerant animals.
What is M mode in echocardiogarphy?
This is when a single ultrasound beam is directed to a very small portion of the heart and the structures interrogated by this beam are plotted against time. a simultaneous ECG allows accurate timing of events in systole or diastole. objective measurements of wall thickness, chamber dimensions and contractility are done from M -mode because of the greater accuracy of timing during the cardiac cycle.
Describe doppler echocardiography?
The change in frequency which occurs when an ultrasound beam hits a moving RBC is proportional to the speed and the direction of the RBC. This information can be converted into a visual display by the ultrasound machine and plotted against time. thus information may be gained about blood flow velocity, flow direction and flow character. Doppler echocardiography is a valuable tool in the diagnosis of congenital and acquired heart disease.
What equations can be used to determine how cardiac diseases affect overall cardiac performance and O2 delivery?
tissue O2 delivery (DO2) = cardiac output (Qt) x arterial oxygen content (CaO2). CaO2 = (SpO2 x Hb x 1.36) + (Pa02 X0.003)
Cardiac output Qt = stroke volume x heart rate
Stroke volume s influenced by preload, afterload and contractility
Describe the cardiovascular functional reserve?
Cardiovascular reserve is the capacity of the cardiovascular system to mete normal physiological challenges e.g pregnancy, excercise, extremes of temperature or volume. the cardiovascular reserve will allow the animal to meet the demands imposed by anaesthesia and surgery. when cardiovascular reserve is exhausted, oxygen delivery falls below oxygen consumption and obligatory anaerobiosis ensues. Cardiovascular reserve is eroded by disease but also by anaesthesia and surgery. The greater the reserve the greater the chance of a successful recovery. Cardiovascular reserve can be decreased by increasing resting effort or by reducing maximal effort.
Name the problems that in crease risks during anaesthesia
animals with cardiovascular disease are at increased risk during anaesthesia because: impaired cardiovascular function is the most important adverse side effect of anaesthetics. Cardiovascular disease adversely affects other organ systems in a way that increases risk. Cardiovascular disease alters drug disposition. The net results are unpredictable drug effects, both in magnitude and duration. the treatment of cardiovascular conditions involves drugs which may interact with anaesthetics.
How can you minimise the risks from surgery and anaesthesia?
Make an accurate diaggnosis i.e recognise the primary effects and assess the animals cardiovascular reserve capacity. recognise secondary complications. recruit cardiovascular reserve pre operatively by adequate preparation. use anaesthetics that offset, rather than aggravate the conditions haemodynamic effects (if the ideal drugs are not available, then use adjuncts to optimise cardiovascular function). Minimise the adverse haemodynamics effects of surgery. Recognise the problems of secondary complications, altered drug behaviour and drug interactions. Ensure adequate peri operative physiological monitoring NB peri operative includes the post operative period.
Describe the pre operative preparation needed before anaesthesia in cardiopulmonary disease patients?
this aims to lower risk by reversing the effects of pre existing disease. where possible treat the primary condition, many secondary complications (e.g related to decreased liver and renal perfusion) resolve as cardiovascular function improves. eliminate retained fluid with diuretics, sodium free diets and interventiosn like pericardiocentesis. reduce cardiac work with vasodilators, cage rest and anxiolytic drugs. control residual arrhythmias if necessary. aim to improve myocardial contractility if necessary. Properly performed, pre operative cardiological preparation purchases cardiac reserve and increases the chance of survival. Side effects of drugs may complicate anaestesia. Pre operative digitalisation can be a problem as digoxin causes arrhythmias and may confuse aetiology. Arrhythmias arising from digoxin toxicity are more likely to occur intra operatively due to changes in blood ph as a result of changes in PaCo2.
Describe local anaesthetic techniques
ajor surgery can be performed under sedation and local anaesthesia providing the surgical site is amenable to local techniques. high sedative doses may cause greater cardiovascular depression than a light general aanesthetic. in addition during sedation the airway and ventilation is often not supported. local anaesthetic injected into the spinal or extradural space can cause profound hypotension that may be catastrophic.
What anaesthetic technique should be used for minor procedures?
Pre anaesthetic medication with a neuroleptanalgesic combination, induction with an ultrashort acting injectable anaesthetic, light general anaesthesia produced with a volatile anaesthetic agent and possibly N2o providing adequate conditions for minor operations in animals with modest disease providing attention is paid to ventilation, temperature, circulating blood volume and peri operative analgesia.
What anaesthetic technique should be used for major proocedures?
Technique for minor procedures would be inadequate in cases wiith advanced disease undergoing major operations because it would not prevent the autonomic nervous responses to noxious stimulation. Balanced anaesthesia i more appropriate in such cases with consideration given to the use of neuromuscular blockade and multimodal analgesic techniques. choose the most apprpriate anaesthetic for a given case by choosing drugs that offset rather than aggravate the conditions haemodynamic effects int he same way you would choose therapeutic agents that is choose drugs with mimic effects of medical therapy e.g the use of acepromazine in cases with MR will reduce afterload, will reduce myocardial oxygen consumption and should reduce the regurgitant fraction.
What should you remember before anaesthesia?
Safe anaesthesia depends on good anaesthetic management, i.e patient position, ventilation, monitoring, fluid administration and temperature management, ogod monitoring will help improve management. adequate anaesthesia with unsafe drugs is safer than under dose or overdose with safer drugs. familiarity with a given technique often proves to be most appropriate. adjuncts may be used to redress imperfections in non ideal drugs. Eg if cardiac output is insufficient with halothane, dobutamine may be infused. nitrous oxide is frequently included because it has modest cardiovascular effects and reduces the delivered concentration of i nhalant dug requireed to produce a given level of anaesthesia.
How does myocardial hypoxia lead to cardiac arrest?
Tachycardia increases myocardial oxygen consumption, decreases the time available for ventricular filling, and in the anaesthetised animal will reduce preload and decrease stroke volume. be aware of conditions that increase resting myocardial oxygen consumption e.g HCM.
Which type of drugs should you choose in cardiopulmonary disease?
choose drugs that least affect ventricular contractility, choose drugs that least affect venomotor tone, choose drugs that reverse the 1st haemodynamic disorder i.e mimic the effects of medical therapy, choose drugs that are compatible with drugs used peri operatively, choose drugs that are suitable in the presence of secondary cerebral,myocardial, hepatic or renal complications. choose drugs that are minimally affected by altered pharmacokinetics. use adjuncts.
How should the cardiac disease patient be monitored?
Good monitoring will help improve anaesthetic management. be aware of limitations of the monitors chosen. ECG. blood pressure: direct or indirect methods. Oxygen: blood gases Pa O2, pulse oximetry, inspired gases. carbon dioxide: blood gases PaCo2, capnography, temperature.
What should the body position be in anaesthesia?
Severe head up body positions will impair venous return while steep head down positions impair breathing, reduce functional residual capacity and lower cerebral perfusion pressure. both positions must be avoided. excessive fore limb fixation with ropes may lower chest wall compliance and increase the work of breathing in spontaenously breathing animals.
What should you bear in mind in surgical manipulation of a cardiac patient?
during operations inolvng the thoracic viscera, unavoidable manulation of the heart and great vessels may limit cardiac output e.g rotating the heart kinks the great veins and impairs ventricular filling. accidental epicardial stimulation with surgical instruments produces ventricular ectopic b eats while the use of cold irrigation fluids impairs contractility.
Which ventilatory mode should be used in cardiiac patients?
Cardiovascular disease frequently affects pulmoonary function. the end results of ventilatory inadequacy - hypercapnia hypoxia or both are poorly tolerated by animals with cardiovascular disease. both are potent arrhythmogens because they simultaneously promote sympathetic nervous activity and increase cardiac work while impairing myocardial contractility. Spontaneously breathing animals normally hypoventilate and retain Co2, howeve the thoracolumbar pum is preserved. Elevated Co2 causes vasodilation which decreases after load and may improve Qt so providing respiratory depression is nto severe, cardiac output may not be unduly depressed. controlled ventilation raises mean intra thoracic pressure and inhibits the thoracolumbar pump causing hypotension. pulmonary vascular impedance increases during inspiration ad momentarily lowers RV stroke volume thus reducing pulmonary blood flow.
How should fluid balance be managed in the anaesthetised patient?
fluid loss, haemorrhage or venodilation are poorly tolerated in conditions which rely on ventricular filling pressures to maintain cardiac output e.g cardiac tamponade. in these, one large bore catheter should be dedicated to fluid adminitratio. Excess fluids are poorly tolerated in animals with increased left atrial pressures e.g hypertrophic cardiomyopathy. ideally fluids are replaced as they are lost, and on a like for like basis. monitoring of central venous pressure is an advantage.
Describe how body temperature should be controlled in the anaesthetised patient?
Hypothermia impairs cardiopulmonary funciton: it depresses ventilation, increases blood viscosity and left shifts the oxygen haemoglobin dissociation curve. arrhythmias may arise spontaneously in the chilled heart with fibrillation becoming increasingly likely as temperatures approach 28 degrees C. it also initiates shivering which increases whole body Vo2 Four fold.
How can neuromuscular blockage and cardiovascular adjunct drugs be used?
Neuromuscular blocking agents may be useful in animals with severe cardiovascular disease however their use may complicate management and may best be avoided by the inexperienced. rapid and short acting versions of drugs used for pre operative preparation can be used during surgery to offset adverse Haemodynamic events e.g antiarrythmics,
What are the elements of cardiovascular reserve?
Increased resting effort > surgical stimulation, anxiety, hypovolaemia, pyrexia, pain, abnormal position, hypoxia, hypercapnia
Limited maximal effort - Disease, anaesthetics, hypothermia, Myocardial disease, advanced age, haemorrhage, electrolyte derangement, sever arterial blood gas derangement.
What are the effects of cardiovascular disease on drug disposition?
Reduced volume of distribution - will decrease the required dose of IVAA. increased circulation time - will increase the time to effect of IV induction agents, reduced cardiac output - will decrease the induction time of inhaled anaesthetics,increased V/q discrepancy will increase induction time with these agents, reduced peripheral perfusion - will prolong redistribution and clearance. Reduced renal blood flow will prolong redistribution and clearance.
Describe depolarisation of the heart
Depolarisation usually begins in the sinoatrial node, which is situateed in the right atrium. Parasympathetic stimulation slows down the rate of discharge of these pacemaker cells, and sympathetic stimulation speeds up the rate. Depolarisation sreads from the SA node to the rest of the right and then left atrial myocardium and reaches the atrioventricular AV node. this corresponds to the Pwave on the ECG. Conduction is particularly slow through the AV node, to allow for time for atrial contraction to fill the ventricles before ventricular contraction occurs. conduction of the impulse from the AV node to the ventricles occurs through the specialised conduction fibres of the bundle of His.
What is the bundle of his?
The bundle of his passes through the electrically insulated annulus fibrosus which separates the atria from the ventricles. this corresponds to the P-Q interval on the ECG. The bundle of his divides into left and right bundle branches which supply the left and right ventricles respectively. The left bundle further divides into anterior and posterior fasicles. The bundle branches divide into smaller and smaller fibres called purkinje fibres which extend into the myocardium. As the depolarisation wave spreads through the ventricles this corersponds to the QRS complex on the ECG. This is followed by repolarisation of the ventricle, which corresponds to the T wave on the ECG.
What is the SA node?
The SA node is the dominant pacemaker, but all of the specialised conduction tissue has innate automaticity i.e will spontaneously discharge. the SA node has the highest rate of discharge and the purkinje fibres have the slowest rate of discharge e.g if for some reason the SA node does not discharge, then the AV node will usually become the dominant pacemaker although the discharge rate will be lower. this is then called an escape rhythm and isolated beats originated from the AV node or more distally are called escape beats.
How can you obtain an ECG?
Patient gently restrained in a right lateral recumbency, avoid sedation if possible, ECG electrodes placed caudal and slightly proximal to the elbow and cranial and proximal to the stifle with gel or surgical spirit applied to increase electrical contact. held on an electrically insulated surface away from mains electrical equipment. Lead configurations - Red - right forelimb. Yellow - left forelimb, Green - left hindlimb, Black - right hindlimb.
What do the uses of ECG include?
The detection of abnormalities of cardiac rate and rhthmn, the detection of evidence of cardiac hypertrophy, the detection of metabolic abnormalities e.g hypoxia and electrolyte disturbances, providing evidence to suggest the presence of poor conduction b betwen the heart and skin surfaces.
Describe good ECG technique?
Clearly labelled, paper speed and vertical calibration, patient details, time and date, minimum of artefact, all 6 frontal plane leads if possible, record some of the trace at 50mm/sec.
What is the heart rate?
Brachycardia - may be sinus arrhythmia, sinus bradycardia, 2nd/4rd degree AV block, atrial standstill and sinus arrest.
Tachycardia - sinus tachycardia, atrial fibrillation, supraventricular tachycardias and some ventricular tachycardias.
What is the rhythm? is it regular or irregular?
Regular rhythmns - sinus rhthmn, sinus tachycardia, supraventricular tachycardias and sustained ventricular tachycardia. Regular irregular rhythm: sinus arrhthmia.
Irregular - irregular rhythm : atrial fibrillation and sinus rhythm interrupted by ectopics.
Is there a P wave for every QRS complex and a QRS complex for every P wave?
P waves without a QRS complex - This indicates atrial depolarization which has not been conducted through the atrioventricular node to the ventricles i.e atrioventricular block.
QRS complex without a p wave - these are either ectopic complexes, atrial fibrillation or sinoventricular complexes (atrial standstill).
Are the P waves and QRS complexes consistently and reasonably related?
Normal PQ interval which remains constant: sinus rhythm
Long PQ interval: first degree atrioventricular block
PQ interval is long and varies: vagal influence on SA node, wenckebach phenomenon.
No consistent relationship of any sort - third degree complete atrioventricular block.
Do all the complexes look the same?
QRS complexes ;
Sinus - normal narrow WRS complexes consistently associated with P wavves.
Supraventricular: normal, narrow QRS complexes
Ventricular: wide and bizarre QRS complexes
P wave complexes:
Suraventricular arryhthmia - different morphology P wave associate with single premature narrow QRS complexes or runs of tachycardia
Wandering pacemaker - high vagal tone can result in variable P waves, normal in dogs.
Do the P waves and QRS complexes measure within normal limits?
The waveforms should be measured in detail, selecting sinus complexes from a lead II recording ideally recorded at 50mm/sec.
What should the normal heart rate be?
70-160 min (adult dogs) 60--140 min (giant breeds) 70-189/ min (toy breeds) Up to 220/ min (puppies) Cat - 120-240 / min
What should the normal P duration be?
<0.04 secs in dogs and cats
What should the normal PQ interval be?
- 06-0.13 in dogs
0. 05 - 0.09 in cats
What is congenital heart disease?
Congenital = any trait present at birth, whether the result of a genetic or non genetic factor significant cause of cardiovascular morbiditiy and mortality in small animal; most common congenital heart diseases of dog are in descending order > subaortic stenosis, PDA, mitral valve dysplasia, pulmonic stenosis and ventricular septal defecets, ventricular septal defects and atrioventricular valve dysplasias are most common in cats
What is aortic stenosis?
Varying degrees of obstruction to the left ventricular outflow tract; lesions may be subvalvular valvular or suprevalvular. seen in boxers, gsds, newfoundland, rottweiler and golden retrievers. Signs are excercise intolerance, syncope, left sided congestive heart failure, sudden death. Systolic ejection type murmur loudest over the left heart base, radiates up the carotid arteries in severe cases. murmur intensity correlates with severity of stenosis. electrocardiography shows left ventricular enlargement, myocardial hypoxia, ventricular arrhthmias. Radiography shows LV enlargement, post stenotic dilation of the aorta. Echocardiography: left ventricular wall thickening, abnormal valvular or subvalvular anatomy, increased outflow velocities on dopler echocardiography, velocities are used to grade the stenosis into mild, moderate and severe. Treatment is prophylaxis for bacterial endocarditis, exercise restriction and adrenergic blocking drugs indicated in moderate to severe cases, breed schemes in place.
What is a patent ductus arteriosus?
Ductus ateriosis connects the main pulmonary artery to the aorta in the foetus, diverts blood from the right heart into the systemic circulation, closure occurs within hours to days after whelpiing, incomplete closure allows continued shunting of blood. Reversed PDA: (right to left shunting) : dogs with large defects may develop severe pulmonary hypertension, causes shunting of un oxygenated blood from the pulmonary artery into systemic circulation. causes chronic hypoxia resulting in increased erythropoeitin release by the kidneys, increased red cell production by the bone marrow and development of polychthaemia. Cavalier King Charles, poodles, springer spaniels, collies, pomeraniens predisposed.
What are the clinical signs of PDA?
Signs of left sided congestive heart failure including coughing, dyspnoea and excercise intolerance, hing limb weakness exacerbated by excercise in cases of right to left shunting defects. A high grade continuous machinery heart murmur, audible loudest over the left heart base steep (water hammer) pulse; right to left shunting defects may have no audible murmur and animals may show differential hind quarter cyanosis. Left atrial enlargement (wide P waves), left ventricular enlargement (tall wide r waves) arrhthmias including atrial and ventricular premature complexes and atrial fibrillation. Left atrial and left ventricular enlargement, pulmonary over circulation, triple knuckle pattern on the dorso ventral view with bulges in the vicinity of the aorta, pulmonary artery and left auricle. pulmonary oedema and congestion. Left atrial and ventricular enlargement, ductus may be visible, doppler echocardiography demonstrates continuous blood flow in the main pulmonary artery. Occlusion of the ductus by surgical ligation or transvenously using ductal occluding devides, left sided congestive heartfailure may require management with use of diuretic and ACE inhibitor therapy.
What is Pulmonic Stenosis?
Obstruction to blood flow through the right ventricular outflow tract, obstruction may be either valvular, subvalvular or supra valvular. boxers, beagles, bull mastifs, bull dogs, cocker spaniels, miniiature schnauzers, terriers and chihuahuas. Clinical signs: excercise intolerance, syncope, ascites, acute death. Auscultation: harsh left heart base systolic murmur often radiates across to the right heart base. Right atrioventricular enlargement (deep S waves in leads I, II ad II, tall P waves). Radiography: right atrioventricular enlargement, post stenotic bulge of pulmonary artery. Right ventricular hypertrophy, structural abnormalities of pulmonic valves and right ventricular outflow tract, doppler echocardiography demonstrates increased velocities through the stenosis; velocities are used to grade the stenosis into mild, moderate, severe. Treat with adrenergic blocking drugs, balloon valvuloplasty and surgical procedures. Sever cases carry a more guarded prognosis and are at risk for a sudden death and right sided congestive failure.
What is mitral valve dysplasia?
Fairly common in dogs and cats, varying degrees of malformation of the mitral valve apparatus, leading to valvular insufficiency and in some cases stenosis. Seen in golden retrievers, english bull terriers and Great Danes. signs of left sided congestive heart failure - coughing, Exercise intolerance, dyspnooea. Auscultation: harsh pan systolic murmur audible loudest over the left apex. Electrocardioography: left AV enlargement pattern, various supraventricular arrythmias may also be noted. Radiography - Left AV enlargement, pulmonary venous congestion and pulmonary edema. Echocardiography: left atrial and ventricular enlargement, structural abnormalities of the mitral valve apparatus may be noted, valvular insufficiency and or stenosis. surgical repair or prosthetic replacement not currently available in the UK, treatment aimed at managing congestive heart failure with a combination of diuretics, angiotensin converting enzyme (ACE) inhibitors and positive inotropics as required.
What is tricuspid valve dysplasia?
Malformation of the tricuspid valve apparatus leading to valvular insufficiency; fairly common in dogs and cats, particularly prevalent in certain breeds of dog. Breed predisposition: labradors, golden retrievers, GSDs, irish setteers, Great Danes, right sided congestive heart failure with ascites and less commonly pleural effusion. Auscultation: harsh systolic murmur audible loudest over the right apex, jugular venous distension and pulsations may also be noted on clinical examination. Right AV enlargement pattern, supraventricular arrhthmias, association between tricuspid valve dysplasia and accessory pathway supraventricular tachycardias in labradors. Right AV enlargement; right atrium often being markedly enlarged. Right atrial and ventricular enlargement; structural abnormalities of the mitral valve appratus, doppler echocardiography demonstrates tricuspid valve insufficiency. Surgically repair or prosthetic replacement not currently available in the UK. treatment aimed at managing congestive heart failure with combination of diuretics, angiotensin converting enzyme inhibitors and positive ionotropics as required.
What are ventricular septal defects?
The most common congenital cardiac abnormality of cats, defect occurs as a result of incomplete separation of the ventricles during foetal development, results in a connection between the left and right ventricles and blood flow may either be from the left ventricle to the right or less commonly from the right to the left. predisposed - keeshonds, english bulldogs and english springer spaniels. left sided congestive heart failure most commonly seen, may also develop signs of right sided heart failure later in life. patients with large defects may present with right to left shunting, hypoxia and resultant polcythaemia.
How can you detect a ventricular septal defect?
There is a pansystolic murmur loudest over the right ventral thorax, murmur intensity not correlated with the size of the defect. Left atrioventricular enlargement (Tall R waves, increased QRS duration, wide P waves). Left atrioventricular enlargement; pulmonary over circulation; signs of left sided congestive heart failure. Echocardigraophy: left atrial and ventricular enlargement, septal defect may be visible, doppler demonstrates blood flow across the defect, high flow velocities suggest a less significant defect, lower velocity flow suggests equilibration of ventricular pressures and hence a more haemodynamically significant defect. Treatment is palliative and aimed at reducing the sign of congestive heart failure, palliative surgery procedures such as pulmonary artery banding may be employed. Poor prognosis if signs of congestive heart failure are present or if right to left shunting develops; small defects often well tolerated and of no clinical significance.
What is tetralogy of fallot?
an uncommon complex congenital cardiac defect, consist of four different abnormalities; ventricular septal defect, pulmonic stenosis, right ventricular hypertrophy and an overriding aorta, results in right to left shunting of blood and resultant chronic hypoxia. Breed predisposition in keeshonds. Clinical signs; stunted growth, poor exercise tolerance, cyanosis and dyspnoea. A murmur of pulmonic stenosis may be audible over the left heart base. right ventricular hypertrophy, right ventricular enlargement and pulmonary under perfusion. echocardiography confirms the presence of a complex cardiac abnormality, right ventricular hypertrophy, ventricular septal defect, pulmonic stenosis, overriding aorta. doppler echocardiography shows right to left shunting of across the ventricular septal defect. Palliative surgical procedures rarely carried out. management directed at Excercise restriction and managing resultant hypoxia and polycythaemia. guarded although some animals will survive for some time with these defects.
What is the normal PQ interval?
- 06-0.13 sec in dogs
0. 05-0.09 in cats
What is the normal R amplitude?
- 0mv in large breeds
- 5 Mv in small breeds
- 9mv (max) in cats
What is the normal S amplitude?
<0.5 mV in cats
What is the normal QRS duration?
- 06 sec in large breeds (max)
- 05 sex in small breeds (max)
- 05 sec in cats (max)
What is the normal Qt interval
- 15-0.25 sec depending on heart rate in dogs
0. 12-0.18 in cats
