EXAMINATION OF

CARDIOVASCULAR SYSTEM

Submittted by:SUMREEN KOUR

MVSc Scholar

Disease of CVS are rare in horses as compared to other species.

Evaluation of CVS is an essential part of physical examination.

Location:2nd ICS to 6th rib.

EXAMINATION Signalment. History taking. Inspection. Palpation. Percussion. Auscultation. Diagnostic aids-electrocardiography. -echocardiography. -exercise testing.

SIGNALMENT Helps to determine likelihood of certain

cardiac problems. Important aspect is age.

Sex-aortic ring rupture in older horses.

Young horses(<3 years old):congenital cardiac problem. Older horses(> 3years old):valvular/conduction disturbance

HISTORY Information about stable condition. General environment Present & past performance Previous disease Vaccination Deworming history Appetite Water consumption Urination & defecation.

INSPECTION Initialy includes :general attitude movement in stall. Prominent juglar pulse with distended vein alerts

the clinician.

VENOUS CIRCULATION:Evalution is difficult because of low pressure.Juglar pulse is seen –reflects right atrial(4mm Hg) & thoracic pressure changes.If head is lowered/ if right atrial pressure is increasedJuglar distention –Right sided CHF.

MUCOUS MEMBRANE COLOUR: Give guide to approximate tissue oxidation & perfusion of capillary bed to assessed area. NORMAL: pale pink(mouth & eye) pink (nasal septum) Bluish/cyanotic (hypoxygenation) dark red(deydration & endotoxemia)

CAPILLARY REFIL TIME:Pressing index finger on MM on gum & above corner incisor tooth.Blanching of MM after which blood will refill-1-2sec.Prolonged CRT-decreased peripheral perfusion.

Facial artery Transverse facial artery near lateral canthus

of eye.

PERIPHERAL PULSE:Pulse character depends on:vessel size distance away frm heart. difference between systolic & diastolic pressures.Increased digital pulse: laminitis.Exaggerated pulse:aortic insufficiencyDecreased pulse:shock & hypovolemia

PALPATION Its important to palpate all four legs,ventral

chest & abdomen for any swelling signs.

Palpation of apex beat –indication of heart in thorax.

Apex beat felt on left ventral chest wall about 10cm dorsal to sternum in5-6 ICS.

If thrill detected on cardiac palpation-severe flow disorder.

AUSCULTATION

INITIAL AUSCULTATION: Examine with stethoscope. Examination starts over area of apex

beat,caudal to triceps muscle & about area 10cm ventral to level of point of shoulder.

25-40 beats/min.

HEART SOUNDS

FIRST HEART SOUND:Generated by closure of left(mitral) & right (tricuspid) artrioventricular valves.Maximum audibility of mitral valve –on left 5th ICS.Maximum audibility of tricuspid valve –on right side at 4th ICS.

SECOND HEART SOUND:Sound generated by closure of aortic & pulmonary valve & is synchronous with end of systole & begining of of cardiac diastole.Aortic component is audible-just ventral to horizontal line drawn drawn through point of shoulder in left 4thICS.Pulmonic component is audible –ventral & anterior to aortic valve at in left 3rd ICS.

THIRD HEART SOUND:Low frequency sound produced with rapid filling of ventricles.Occurs immediately afer 2nd sound.Common n horses.

FOURTH HEART SOUND:Associated with atrial contraction.

SEQUENCE:4-1-2-3In horses 3rd & 4th may be inaudible.

HEART MURMURS Murmurs are audible successive sounds with

distinct duration as opposed to heart sound which are short & transient.

Prolonged audible vibrations occuring during normal silent period of cardiac cycle.

Problems resulting in heart murmurs are: Decreased viscosity. Condition producing increased cardiac

output. Abnormal blood flow. Temporary mumurs can be heard in colic

also.

ELECTROCARDIOGRAPHY ECG provides record & measure of

varying potential difference that occur over surface of body as result of electrical activity within heart.

RECORDING TECHNIQUES: Need quite place. Minimum interference. Rubber mat for horse. Dry area. Paper speed=25mm/s & sensitivity of

1cm=1mV.

TWO MAIN TYPES: METAL ELECTRODE THAT

ARE CONNECTED TO LEG BY RUBBER STRAP:

Electrodes are applied on forelimb caudal aspect of distal radius just proximal to carpal bone.

Electrodes are applied on hindlimb at cranial aspect of of distal tibia above point of hock.

Chest electrode -5cm behind point of elbow on left ventral thorax.

BIPOLAR LEAD SYSTEM USING Y LEAD:

Positive lead attached over xiphisternum.

Negative lead attached over manurium.

Earth lead can be attached over point of shoulder.

INTERPRETATION OF ECGExamine complete tracing to note any abnormal rhythm.

Determine wether P wave,QRS complexes,T wave are present for each heart beat .

Assess individual wave formation & measure intervals.

EVALUATION OF ECG WAVEFORMS & INTERVAL P wave: Represents

artrial depolarization.

Appears M shaped.

NORMAL:2 boxes (width)4 boxes (height)

PR interval: Beginning of P

wave to beginning of QRS complex.

Interval depends on heart rate & shorten as HR increases.

In older horses-PR interval lengthens.

PR interval:3-61/2boxes (width)

QRS complex: Represents

ventricular deporalizaton.

QRS interval:3boxes (width)

25 boxes(height)

T wave: Represents

ventricular depolarization.

Its extremely sensitive to change in HR with change in amplitude & polarity.

QT interval: Beginning of QRS

comple to end of T wave.

Littl significance. Shorten with

increase in HR.QT wave:

8-13 boxes(width)

HEART SCORE CONCEPT Developed by Dr. Jim Steel in 1950s. Its indirect method of assessing heart

size & is determined by measuring QRS complex duration in milliseconds in lead I.II.III & averaging the result.

Average HS =113-116( >120 indicates above average heart size).

ECHOCARDIOGRAPHY Equine cardiology Introduced by Pipers

& Hamlin in late 1970s. Useful in investigating congenital &

acquired heart disease. Techniques permits real time imaging of

heart,allowing quantitation of cardiac dimensions,identification of lesions & estimation of cardiac compensation & myocardial failure.

2.5-3.5MHz transducer is used. Pentration depth should be 24cm.

5 TECHNIQUES ARE AVAILABLE:

M –mode

B-mode/two dimensional real time

Continuous –wave doppler

Pulsed-wave doppler

Color-flow doppler

RIGHT PARASTERNAL LONG-AXIS VIEWS:

VIEW:taken from right hemithorax of horse witg transducer placed at 5th,4th/3rd ICS.1.REFRENCE VIEW:4th ICS perpendicular to thoraxic wall.Structures imaged are:TV,RA,IVS,IAS,LV,MV,LA,LVFW.

2. APICAL VIEW:transducer is rotated 90 degree counterclockwise from refrence view.Structure imaged are:RA,TV,RV,LV,IVS,LA.

3.LONG AXIS VIEW:rotated to 30 degree clockwise.Struccture imaged are:RV,RA,LV,AO,PA.

RIGHT PARASTERNAL SHORT—AXIS VIEWS:Transducer is rotated 90 degree counterclockwise from refrence position .Strcture imaged:RV,LV,RVW,LVW,chordae tendinae.

PULSE WAVE DOPPLER Used to obtain hemodynamic

information from all four heart valves. Doppler sample of aortic outflow from

LHS & aortic diameter from RHS are measured & resulting outflow combined with HR.

EXERCISE TESTING & TELEMETRY Dyspnea,fatigue & prolonged elevation

in HR following exercise are suggestive of cardiac insufficiency.

Clinical exercise testing is performed with treadmill inclined at slope oof 6 degree & then horse progress through trotting,cantering & galloping at speed upto 12m/s.Protocol:3 min- 4m/s90sec – 6m/s1 min – 8,10,11,12 m/s until horse cannot maintaine pace with treadmill.Most fit horses complete test upto 11m/s.

RECORDING OF ECG DONE BY TELEMETRY IS USEFUL TO DETERMINE ABNORMALITY OCCURS(30-60SEC AFTER HORSE STOPS FAST EXERCISE)

PERICARDITIS Its defined as

inflammation of pericardium.

It may be fibrinous or adhesive depending on nature of inflammation.

Predominently occurs in adults.

ETIOLOGY Trauma from penetration of ingested FB

or external wound. Hematogenous spread of infection. Idiopathic pericarditis-characterised by

aseptic inflammatory exudate. HORSE: Streptococcus species. Tuberculosis. Actinobacillus equi. EHV-1 infection.

PATHOGENSIS As result of inflammation of pericardium

Accumulation of fluid occurs.

Deposition of fibrinous exudate produces friction sound when pericardium & epicardium rub together.

Friction sound replaced by muffling sound

Accumulation of fluid results in compression of atria & rt venticle.

CHF follows Severe toxemia due to supparative pericarditis

CLINICAL FINDINGS Increased HR. Pulse weak & thready. Muffled heart sound. Juglar vein distension. Ventral odema. Dyspnea. Alteration in mucous membrane. Prolonged capillary time. Clinical pathology: Leukocytosis & shift to left is detectable. Pericardial fluid for bacteriological

examination.

NECROPSY Hypermia. Deposition of

fibrin Gas may also be

present & fluid may have putrid odor.

Embolic abscesses may be present in other organs.

TREATMENT Pericardiocentesis done. Antibacterial treatment of specific infection. Braod spectrum antibiotic should given. Combination of penicillin & gentamicin is

common. NSAIDS given as an effective therapy.

ENDOCARDITIS DEFINITION :- It denotes inflammation of the

endocardium. It affects the lining of the heart as well as the valves within it.

Most of the cases are caused by bacterial infection. Infection may gain entry through

Direct adhesion to undamaged endothelium.

Through minor discontinuities of valvular surfaces.

By hematogenous route.

ETIOLOGY:

Actinobacillus equi. Streptococcus spp Pseudomonas. Strongylu spp larvae.

PATHOGENESIS Trauma to the endothelial surface

Exposure of collagen leading to platelet binding

Activation of extrinsic coagulation cascade

Deposition of fibrin

Formation of sterile platelet-fibrin deposits

Endothelial damage may occur along the lines of closure of valves in association with turbulent flow.

These areas of endothelial damage are

colonized by circulating bacteria where they start growing.

In large animals, endocarditis occur most commonly secondary to a chronic infection and a persistant bacteremia, whereas certain organisms adhere directly to endothelium

The major clinical abnormalities result from :-

effect of endocarditis on heart function

embolic showering of micro organisms leading to infarction or infection

valvular lesions which interfere with valve function lead to cardiac insufficiency

infected emboli produce infection or abscesses in other organs like myocardium, kidneys, joints

In horses most common site:aortic valve.

Left & right Arterioventricular valves being 2nd & 3rd prediliction sites

CLINICAL SIGNS Intermittent fever, Dull & deppressed. Heart murmur. Vegetative lesions in echocardiography. Coughing. Ventral odema.

CLNICAL PATHOLOGY:neutrophilia hyperfibrinogenemia

A non-regenerative anemia

TREATMENT Treatment is often unrewarding.

Long term antibiotic therapy is required to cure

bacterial endocarditis.

Penicillin and gentamicin are the drug of choice for bacterial endocarditis..

THANK YOU