Cardiac SAM Exam 5

Breed predispositions

• Dobermans: DCM

• Boxers: ARVC

• Maine Coons: HCM

• Cavaliers: Mitral valve degen

• Westies: Pulmonary Fibrosis

• GSD: Endocarditis

Normal Cardiac Auscultation

• Point of maximal intensity

  • Pulmonic: Left 3 ICS

  • Aortic: Left 4 ICS

  • Mitral: Left 5 ICS

  • Tricuspid: Right 4 ICS

• S1: Apex, Mitral, Tricuspid valves

  • Longer & lower pitched

• S2: Base, Aortic, Pulmonic valves

  • Shorter & higher pitched

Abnormal Cardiac Auscultation

• Diastolic dysfunction: gallop sound

  • S3: Ventricular gallop

  • S4: Atrial gallop

• Systolic dysfunction: click sound

  • mitral/tricuspid regurge

• Murmurs: valvular dysfunction

  • 2/6 systolic murmurs common in puppies, grow out of it

• Increased Sounds: High tone/heart size/output

• Decreased Sounds: Low output, effusion, myocardial infarction failure, obesity, mass

Murmur Grades

1. Intermittent, 1 valve

2. Consistent, 1 valve area

3. Multiple valves

4. Multiple valves, loud

5. Palpable thrill

6. Can hear w/o stethoscope

Arterial Pulse

• Weak Pulses: Poor perfusion, Shock, Heart failure, Aortic stenosis

• Pulsus Paradoxus: inspiration, Pericardial dx w/ tamponade

• Bounding Pulses: situational, shock, Aortic insufficiency, PDA, Hyperthyroidism

Cardiac Radiographs

• DV views: best for cardiac structures

• Left Enlargement:

  • LV: tall w/ lateral projection

  • LA: Loss of caudal waist, lg bronchus (cowboy)

• Right Enlargement:

  • RV: wide silhouette, sternal contact, reversed D

Vertebral Heart Score

• Equation = # Vertebral bodies starting @ 4VB + length AB

  • A: Carina down @ 90°

  • B: Widest part of heart

  • Normal: <10.5

Pulmonary Radiographs

• VD views: best for pulmonary parenchyma

• Vessels: compared to each other, proximal 1/3 of the 4th rib on lateral or 9th rib on VD

  • Prior diuretics may normalize pulmonary veins even w/ CHF

Echo Components

• Probes Frequency

  • High: resolution

  • Low: penetration

• Doppler

  • Colour: Blue Away, Red Toward, Green turbulence

  • Continuous: velocity of valve regurg

  • Pulse: low velocity, diastolic dx

Echo assessment of cardiac function

• Systolic: Ejection fraction, Fractional shortening, Cardiac Output

• Diastolic: E/A ratio (Mitral inflow), Doppler, Left Atrial Volume Index

Setting up an ECG

• Position: Right Lateral

• Settings: fastest paper speed, highest voltage possible 

• Leads:

  • 1: R arm -> L arm

  • 2: R arm -> L leg

  • 3: L arm -> L leg

Reading an ECG

• Use: ID ectopic beats, bradyarrhythmias, tachyarrhythmias

• P-wave: Atrial depolarization, precedes QRS-complex

  • If not visible: increase amp, turn off filter

• QRS complex: Ventricular depolarization

• T wave: Ventricular repolarization

  • ST Segment Changes = ischemia

• Heart rate: 6 sec X 10 or 1sec 25–50 mm, or marked

Sinus Rhythms

• Bradycardia: outside influence

  • MOA: ↑ vagal tone from dx

  • ID: Normal PQRS, regular rhythm, slow rate

  • TX: atropine or glycopyrrolate

• Tachycardia: outside influence

  • MOA: Pain, anemia, dehydration

  • ID: Normal PQRS, regular rhythm, fast rate

AV Blocks

• 1st Degree: outside influence/drugs

  • MOA: High vagal tone, drugs

  • ID: Prolonged PR, QRS for every P, regular rhythms

  • No treatment normally

    

• 2nd Degree

  • ID: Atropine response test**, not a QRS for every P, regular rhythms

  • TX: pacemaker(high grade), Atropine**, Glycopyrrolate, Propantheline, Isoproterenol, Theophylline, Terbutaline

    

    • High grade 2nd Degree AV block: structural

      • Atropine test - pacemaker

• 3rd Degree

  • ID: No a QRS for every P, escape rhythms, syncope if no escape rhythm

  • TX: pacemaker, Atropine, Glycopyrrolate, Propantheline, Isoproterenol, Theophylline, Terbutaline

    

Sinus Node & Atrial Disorders

• Sick Sinus Syndrome

  • ID: tachy-brady cardia, no escape beats, irregular rhythm, no P waves for >2 sec

  • TX: pacemaker, Atropine, Glycopyrrolate, Propantheline, Isoproterenol, Theophylline, Terbutaline

  

• Atrial Standstill: CHECK Potassium

  • MOA: Hyperkalemia, Atrial cardiomyopathy

  • ID: No P waves

  • TX: Calcium gluconate, dextrose, Insulin, 0.9% NaCl

    • If k+ normal: pacemaker

  

Premature Complexes & Tachyarrhythmias

• Atrial Premature Complexes

  • MOA: Valve disease, DCM, neoplasia

  • ID: Early P wave, QRS normal

• Supraventricular / Atrial Tachycardia

  • ID: Narrow QRS, fast rate, abnormal P wave

  • TX: Digoxin, Atenolol, Diltiazem, Sotalol, Procainamide

. ^^Pathologic supraventricular tachycardia and sinus tachycardia^^

^^Sinus with supraventricular premature complex^^ L Mitral murmur

• Atrial Fibrillation / Flutter

  • ID: No P waves, Irregular R-R intervals, sawtooth

  • TX: Digoxin, Diltiazem, Atenolol**, Quinidine, Amiodarone, Sotalol, Procainamide

Ventricular Premature Complexes

• MOA: Boxers, Dobermans

• ID: Wide bizarre QRS w/o P wave

• TX: Flecainide, Sotalol, Atenolol, Amiodarone, Mexiletine, Procainamide

Ventricular Arrhythmias

• Ventricular Tachycardia

  • ID: Wide, fast QRS

  • TX: Lidocaine, Amiodarone, Procainamide, Esmolol

• Idioventricular Rhythm (slow V tach)

  • MOA: GDV, splenic disease, sepsis

    • 120-160 bpm

  • ID: Wide, slow QRS

  • TX: Pain control- if needed, potassium correction

  • BENIGN neglect - no treatment

    • EX: Post operative splenectomy

• Ventricular Fibrillation

  • ID: Chaotic, disorganized rhythm

  • TX: Defibrillation

Miscellaneous ECG Issues

• Left Bundle Branch Block: (lead 2 + = left)

  • ID: Wide QRS

  • DDx: mimic VPC

• Electrical Alternans

  • MOA: Pericardial effusion, supraventricular arrhythmias

  • ID: Alternating QRS height

Natriuretic Peptides (BNP)

• MOA: Cardiac stretch or increased pressure

• Use: DCM, HCM

• SNAP: symptomatic cats only

• Issues: Thyroid and renal dysfunction

Troponin

• MOA: Myocyte Injury

  • Myocarditis, Ischemia, Cardiomyopathies, Neoplasia

• Issues: Sepsis, Renal failure, Toxins, Systemic illness

Nutritional Cardiomyopathies

• Types: Taurine, Carnitine

• MOA: DCM, Cocker Spaniels

Genetic Testing for Cardiomyopathies

• Use: Predictive

• HCM Test: Ragdoll, Maine Coon, Sphynx

• DCM/ARVC Test: Boxer, Doberman, Ridgeback, Newfie

Valvular Degeneration

• MOA: Older Sm dogs, Cavaliers, Mitral > Tricuspid

  • Not endocarditis

• Sequelae: Volume overload, resp compression, Left CHF, SupraVent arrhythmias, Chordal rupture, Left atrial tear, Jet lesions

Staging and treating Congestive Heart Failure

• B: Asymptomatic w/ enlargement

  • TX: Pimobendan: B2 & higher, ACE inhibitors, or none, SX

    • B1: normal BP = no tx

• C: CHF signs present

  • TX: Pimobendan, ACE inhibitors, Furosemide: C & higher, Spironolactone, SX

• D: Refractory CHF

  • ID: BUN 85, Creat 2.5

  • TX: Pimobendan, ACE inhibitors, Furosemide, Spironolactone, Injectable Lasix, Hydrochlorothiazide, Nitroglycerin, SX

Pulmonary Hypertension

• MOA: Right-sided murmur, lung disease, heartworm, L→R shunts, thromboembolism

  • West Highland White Terriers

• CS: Weakness, Shortness of breath, Fainting/syncope, Cough

• ID: R side enlargement, Enlarged pulmonary arteries, HW testing, RPAD <30%

  • Consider heat-fix HW testing 

• TX: Diuretics, ACE inhibitors, Pimobendan, Sildenafil, Clopidogrel, Toceranib, SX, Immiticide, Diroban

  

Dilated Cardiomyopathy (DCM)

• MOA: Great Danes, Dobermans, Wolfhounds, Ragdoll, Maine Coon, Sphynx

• CS: Resp distress, coughing, exercise intolerance, syncope/sudden death, ascites

• ID: Low-grade murmur, Soft S1/S2, Crackles/wheezes, A-fib, tachycardia, LV & atrium dilation, systolic dysfunction

• TX: Mexiletine, ACE Inhibitors, Furosemide, Pimobendan, Spironolactone, Digoxin

  • Avoid boutique, exotic, grain-free diets

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

• MOA: Boxers, Irish Wolfhounds, Ragdoll, Maine Coon, Sphynx

• CS: Asymptomatic, exercise intolerance, syncope/sudden death

• ID: Holter test

• TX: Sotalol, Mexiletine, Atenolol, Fish oils

Hypertrophic Cardiomyopathy (HCM)

• MOA: LV/LA wall thickening

  • Breeds: Ragdoll, Maine Coon, Sphynx

• ID: Echo, genetic test, high BNP, pulmonary infiltrates

• Rule out: Hyperthyroidism, Hypertension, Hypersomatotropism

• TX: Furosemide, ACE Inhibitor, Clopidogrel, LMWH, Aspirin, Atenolol, Diltiazem: (if asthma/bronchitis)

Hypertrophic Obstructive Cardiomyopathy (HOCM)

• MOA: Mitral valve pulled toward septum during systole causing LVOT obstruction

  • Subtype of HCM

• ID: SAM of mitral valve on ECHO

• TX: Atenolol, Furosemide, ACE Inhibitor (Enalapril), Clopidogrel, LMWH, Aspirin, Atenolol, Diltiazem

Restrictive Cardiomyopathy (RCM)

• MOA: Endocardial fibrosis, impaired ventricular filling

  • Breeds: Ragdoll, Maine Coon, Sphynx

• ID: Normal wall thickness and systolic function, Bi-atrial dilation, atrial arrhythmias may occur

• TX: Furosemide, ACE Inhibitor, Clopidogrel, LMWH, Aspirin, Atenolol, Diltiazem

Unclassified Cardiomyopathy (UCM)

• MOA: Doesn’t fit into HCM/RCM/DCM categories

  • Breeds: Ragdoll, Maine Coon, Sphynx

• ID: Atypical or mixed patterns

• TX: Symptomatic dependent

Heart Failure

• MOA:

  • Right Side: Pulmonary edema

  • Left Side: Ascites, pleural or pericardial effusion

• CS: Dyspnea, crackles/wheezes, coughing (dogs), pleural effusion (cats), abdominal distension, fluid wave, hepatomegaly, muffled heart/lung sounds

  • Cats don't cough

• ID: Echo, BNP, Troponin, T4 (cats >7y), ECG, BP, LA enlargement, pulmonary venous congestion, pulmonary infiltrates

• TX: Nitroglycerin, Pimobendan, Butorphanol, Dobutamine, Nitroprusside, Furosemide, ACE inhibitor

  • Avoid: Fluids, beta-blockers, diltiazem

Common Cardiac Medications

• Nitroglycerin: Preload, CHF

• Furosemide: Preload, CHF

• ACE inhibitor: Afterload, CHF, cardioprotective

  • -pril

• Pimobendan: Inodilator, CHF

• Sedation: Butorphanol

• Dobutamine: Cardiogenic shock (cats)

• Nitroprusside: If hemoptysis and normotensive

• Sildenafil: PDE-5 inhibitor, hypertension 

• Tadalafil: PDE-5 inhibitor, hypertension 

• L-arginine: nitric oxide precursor, hypertension 

• Theophylline: PDE-4 inhibitor, hypertension 

• Beta blockers: Antiarrhythmic, not for CHF, cardioprotective

  • olol

Hypercoagulation Disorders

• MOA: Heart dx, protein-losing dx, hyperadrenocorticism (Cushing’s), IMHA, neoplasia

• CS:

  • Right Heart Emboli: Respiratory signs (dyspnea, tachypnea)

  • Left Heart Emboli: Limb paralysis, seizures, acute renal failur

• ID: TEG, Sonoclot, Antithrombin III levels, Proteinuria

• TX: Opioids, Heparin, Clopidogrel, Aspirin, Dabigatran, Apixaban / Rivaroxaban, SX

Aortic Thromboembolism in Cats

• MOA: Often left side, HCM, saddle thrombus

• CS: Absent/reduced pulses, cold limbs, pain, LMN signs, quick-to-bleed toenails

• ID: Elevated CK/ALT/AST, ECHO

• TX: Opioids, Heparin, Clopidogrel, Aspirin, Dabigatran, Apixaban / Rivaroxaban, SX

  • Prognosis: 50/50, watch for reperfusion injury

Pulmonic Stenosis

• MOA: Dogs, valvular > sub/supravalvular, congenital

• CS: Left systolic murmur

• TX: Beta blockers, Balloon valvuloplasty (not for Boxers/Bulldogs)

Patent Ductus Arteriosus (PDA)

• MOA: Persistent connection between pulmonary artery and aorta, congenital

• CS: Continuous murmur, hyperdynamic (water hammer) femoral pulses

• ID: Echo, rads, Doppler with continuous flow peak velocity >4 m/s

• TX: Surgical ligation, ductal occlusion (ACDO)

Ventricular Septal Defect (VSD)

• MOA: #1 congenital defect, communication between R and L ventricles; paramembranous > muscular or subpulmonic

  • Left side overload

• ID: Echo and Doppler with high velocity

• TX: Palliative pulmonic banding, ACE inhibitors, Pimobendan, Diuretics

Subaortic Stenosis (SAS)

• MOA: Valvular or supravalvular

• CS: Loud left basilar systolic murmur, weak pulses

• TX: Beta blockers, ACE inhibitors, Furosemide

  • Not surgical candidates

Tricuspid Valve Dysplasia

• MOA: Labs, thickened valve, shortened chordae, tethered leaflets, congenital

• CS: Right apical systolic murmur

• ID: Splintered QRS on ECG

• TX: Furosemide, Enalapril, Pimobendan

Mitral Valve Dysplasia

• MOA: Thickened valve, short chordae, restricted leaflet motion, congenital

• CS: Murmur at left apex, supraventricular arrhythmias

• TX: ACE inhibitor, Pimobendan

Atrial Septal Defect (ASD)

• MOA: Septum primum, septum secundum, sinus venosus, patent foramen ovale; congenital

• CS: Right volume overload, no murmur, Split S2 heart sound

• TX: Surgical closure

Reversed Shunts (PDA, ASD, VSD)

• MOA: Pulmonary hypertension, R → L shunting, congenital

• CS: No murmur, cyanosis, exercise intolerance, polycythemia

• TX: Phlebotomy, Hydroxyurea, Sildenafil, L-arginine, Pimobendan

Persistent Right Aortic Arch (PRAA)

• MOA: Congenital

• CS: GI upset

• ID: Rads

• TX: Surgical excision of ligamentum arteriosum

Pericardiocentesis

• Indications:

  • Diagnostic sampling

  • Treatment for cardiac tamponade or hemodynamically significant effusion

• Technique:

  • Right side, 4th/5th intercostal space, just dorsal to costochondral junction

Aortic Body Tumor (ABT)

• MOA: Brachycephalic breeds, pericardial disease

• CS: Collapse, weakness, dyspnea, cough, vomiting, muffled heart/lung sounds, weak femoral pulses, pulsus paradoxus, ascites

• ID: Electrical alternans on ECG with ventricular ectopy, globoid heart on rads, pericardiocentesis, cytology

• TX: Pericardectomy

Hemangiosarcoma (HSA)

• MOA: Right atrium/auricle, pericardial disease

• CS: Collapse, weakness, dyspnea, cough, vomiting, muffled heart/lung sounds, weak femoral pulses, pulsus paradoxus, ascites

• ID: Same as ABT

• TX: Doxorubicin (chemo)

Peritoneopericardial Diaphragmatic Hernia (PPDH)

• MOA: Congenital, abnormal fusion of septum transversum with pleuroperitoneal folds

  • Not related to trauma

• CS: Collapse, weakness, dyspnea, cough, vomiting, muffled heart/lung sounds, weak femoral pulses, pulsus paradoxus, ascites

• ID: Electrical alternans on ECG w/ ventricular ectopy, globoid heart on rads, pericardiocentesis, cytology, ultrasound

• TX: Surgery if necessary (NOT ALWAYS NEEDED)

Interpreting Blood Pressure Readings

• Systolic: Pressure during ventricular contraction

• Diastolic: Pressure during relaxation

• MAP: Average pressure during cardiac cycle

  • MAP = (2 × Diastolic + Systolic) ÷ 3

  • MAP = Diastolic + 1/3(Systolic – Diastolic)

Methods of Measuring Blood Pressure

• Doppler: Non-invasive

  • Cuff = 40% of limb

  • Average 5 readings, 30 sec 

• Oscillometric: Automated, anesthesia patients, gives HR 

• Invasive: Arterial Line, direct, Gold standard

Systemic Hypertension

• MOA: Cushing’s, Hyperthyroidism, CKD, Pheochromocytoma

  • Lowers testing threshold 

• ID: MAP >145 mmHg, Systolic >180 mmHg (dogs) or >160 mmHg (cats)

• TX: Na nitroprusside, Hydralazine, Amlodipine, ACE inhibitors, Telmisartan (cats)

Endocarditis

• MOA: Bacteremia (bartonella) mitral/aortic valves, L > R side, Lg dogs, GSD, males

  • Subaortic stenosis: Only structural dx w/ increased risk

  • Recent corticosteroid use

• CS: Fever, Lameness, Seizures, Heart murmur, CHF signs, Hyperdynamic pulses 

  • Dental disease: No significant correlation

• ID: Culture - 3 different samples, 3 different sites

  • CBC/Chem/UA: infection signs 

  • ECG: Premature atrial/ventricular beats, AV block

  • Echo: Vegetative valve lesions, Regurgitation

  • Bartonella: PCR/serology - takes too long

• TX: Azithromycin, Doxycycline + enrofloxacin, Gentamicin/aminoglycosides, Furosemide, ACE inhibitor, pimobendan, spironolactone

  • No gold standard therapy for Bartonella