Cardiovascular system Flashcards
Physical exam
Inspection
Palpation
Auscultation
Percussion
Palpation
Location and intensity of heartbeat Heart rate Trauma, deformity Pain Precordial thrill, fremitus
Percussion method and use
Pleximeter and percussion hammer
To detect pain in the cardiac area
Where is the area of cardiac dullness?
Diernhofer triangle- dullness on the left side
Ancillary diagnostic methods
ECG Echocardiography Phonocardiography Blood pressure measurement Pericardiocentesis Cardiac catherisation Lab tests
ECG
Resting:
Base apex lead: most commonly used
(einthoven rarely)
Holter and telemetric:
At rest or
While exercising
Lab tests
Blood tests
- AST
- CK in humans MB but in horses MM
- LDH and 5 isoenzymes- mainly LDH1 (LDH2)
- Cardiac troponin I and T
Location of heart
Base: btw 2nd and 6th ICS
Twisted aniclockwise
Right side: cranially
Ledt side: Left and caudally
Location of heart beat
Left: 3-5 ICS
Right: 3-5 ICS
Heart sounds: S1
Beginning of systole
Initial movement of ventricle
AV valves tense, stopping of blood flow
Early part of ejection
Heart sounds: S2
End of systole
Change in direction of blood flow
Closing of semilunar valves
Heart sounds: S3
Termination of rapid ventricular filling
Can be heard at or caudal and dorsal to the apex beat
Heart sounds: S4
Atrial contraction
Arrest of the distended ventricle
Heart murmurs
Prolonged audible vibrations
Develop in a usually quiet part of the cardiac cycle
The normal/ functional murmurs
Caused by vibrations after the ejection of blood during systole
OR
Rapid filling of the ventricles during early diastole
Physiological (flow) murmurs
Systolic or Diastolic
Systolic murmur
Caused by blood flow in aorta and pulmonary artery in early systole Left side of thorax PMI over aortic or pulmonary valves Grade 1-3/6 Early-to-midsystolic Crescendo-decrescendo or decrescendo Localised and brief
Diastolic murmur
Caused by ventricular filling Common in young and thoroughbreds Left side of thorax PMI over mitral area Grade 1-3/6 Early diastolic (S2-S3) or late diastolic (S4-S1) Musical/squeaking
Classification of endocardial murmurs
Timing Duration Grade Point of maximum intensity PMI Quality (shape) Frequency Radiation Effect of changing heart rate
Timing
Early
mid
late
Grade
1/6: quiet-requires careful auscultation
2/6: quiet: heard when stethoscope placed over its PMI
3/6: audible over a wider area
4/6: loud and audible. no fremitus
5/6: fremitus and audible with loose contact with the thoracic wall
6/6: loudest even audible when the stethoscope is held apart from the thoracic wall
PMI Pulmonary
Left 3rd ICS below point of the shoulder
PMI Aortic
Left 4th ICS below point of the shoulder
PMI mitral
Left 5th ICS halfway between shoulder and sternum
PMI Tricuspid
Right 4th ICS
Basic interpretation of ECGs
Aretfacts can be present, especially in exercise racehorses
Heart rate
Rhythm (R-R intervals):
normal
regularly irregular
irregularly irregular– atrial fibrillation
Relationship between P waves and QRS complexes:
each P wave is followed by a QRS complex
each QRS complex is preceded by a P wave
Duration and morphology of waves, duration of segments and intervals
Unique to equine ECG
No Q wave
Large negative deflection in the S-wave (not R wave)- but still the R waves are used to describe
Sinus rhythm
Biphasic P
Positive T-wave that can be biphasic as well
Atrial premature complex/ depolarization (APC/APD)
3rd cycle: P-wave is earlier than normal– after this normal QRS and P, the P wave is not too early, the ventricular muscle can contract
If P wave more premature- ventricular muscle still in refractory period and the stimulus doesn’t get through AV node- no depolarization, no QRS complex and T-wave
5th cycle: almost no gap between T and P wave
Can cause exercise intolerance
Atrial fibrillation
Normal QRS complex and T wave
No visible P waves- instead many small f-waves
S-S intervals are very irregular, therefore irregular rhythm
S sound not audible
Exercise intolerance and poor performance
Very common
1st and 2nd degree atrioventricular block
1st and 2nd degree at the same time
1st cycle: P wave not directly followed by QRS complex, the duration of atrioventricular conduction through AV is longer
Followed by 4 normal cycles
T-wave (late) and P-wave (normal timing) almost together
2nd degree: ventricle muscles in refractory, no contraction, no QRS complex and no T-wave
Block usually repeated after a few normal cycles, most of the 1st and 2nd degree are normal because of the strong vagal tone, this is why you can check if it is physio by walking the horse around- will become excited and the vagal tone won’t be as strong and HR increases, so no more blocks
2nd degree atrioventricular blocks
P wave not followed by a QRS
NB!! ECG software can misinterpret T-waves for QRS complexes, giving a double HR- this is why auscultation is so important
3rd degree (complete) atrioventricular blocks
Complete separation of atrial and ventricular depolarization- no conduction through AV node
P wave is normal- indication that SA node is normal
There is automatic pacemaker activity in ventricular muscle, it will contract even though there is no info coming through the AV node
This is why we can see 3 ventricular contractions that are much slower
Extreme level of exercise intolerance
Resolution: pacemaker
Ventricular premature complex/ depolarization (VPC/VPD)
Originates in ventricle
Different wave forms: 1st (half one) normal and then no visible P-wave
Every 2nd cycle abnormal
CO decreases because the abnormal contraction can’t produce same HMV
Always clinical signs- exercise intolerance and poor performance
Ventricular tachycardia VT (uniform)
Resting ECG is 140 bpm
QRS and T-wave identifiable, but P-wave is not
Can be temporary with sinus-rhythm
Origin of the premature ventricular rhythm is the same
Ventricular tachycardia (multiform)
HR very high
Different wave form, variability in QRS complex
Different origins in the ventricular muscles
If sustained– ventricular fibrillation— heart stops
