Wendy Blount, DVM Nacogdoches TX Thoracic Radiology Wendy Blount, DVM Nacogdoches TX

Thoracic Rads - Normal Why is it so difficult to evaluate cardiac and chamber size on radiographs? Comparing heart size to lung field size doesn’t work Dogs of different conformation have different ratios of heart size to lung size Lung field size changes with the breathing cycle Abdominal fat pushes the diaphragm cranially Thoracic fat makes lung fields appear smaller Comparing heart size to vertebral size works better Vertebral heart score

Thoracic Rads - Normal Why is it so difficult to evaluate cardiac and chamber size on radiographs? Things can make the heart look bigger Pericardial fat Pericardial effusion Peritoneopericardial diaphragmatic hernia Oblique positioning on VD/DV can make right heart look bigger MYTH - “increased sternal contact” means right heart enlargement

Thoracic Rads - Normal Normal cats change with age Long axis of the heart is more horizontal in old cats (40%) Aortic bulge (30%) Not due to hypertension or hyperthyroidism At the aortic isthmus Measurements in young & old cats are the same

Thoracic Rads - Normal Vertebral Heart Score Measure heart long axis 5.0 + 4.8 = 9.8 Vertebral Heart Score Measure heart long axis carina to the apex Measure heart short axis Widest perpendicular to length Count vertebrae from cranial aspect T4 Add together Dogs – normal 8.5-10.5 Cats – normal 7-8

Thoracic Rads - Normal Heart Chambers – VD/DV LV 3-6 o’clock Aorta 12-1 o’clock RV 5-9 o’clock MPA 1-2 o’clock LA has to be really big to see on VD RA 9-12 o’clock

Thoracic Rads - Normal Review of thoracic radiographs Skeletal Spine, front limbs, ribs, sternum Cranial abdomen Airways, Lung fields Great vessels Aorta, pulmonary arteries, cranial & caudal vena cava Smaller vessels Internal thoracic arteries, pulmonary lobar a & v, brachiocephalic trunk, left subclavian artery Cardiac silhouette Vertebral heart score, bulge Left Heart Failure? Right Heart Failure?

Thoracic Rads - Normal Heart Chambers – Lateral LA – caudal waist – 12-3 o’clock LV 2-6 o’clock Aorta 10-11 o’clock Raur 9 o’clock (RA not on lateral) RV 6-9 o’clock MPA 11-12 o’clock normal Bulge often 1-2 o’clock

Thoracic Rads - Abnormal 6.2 + 5.9 = 12.1 Case #1 – 8 year old neutered male cocker spaniel - coughing Skeletal Cranial abdomen No abnormalities noted Airways, Lung fields Mild perihilar edema Great vessels enlarged caudal vena cava Smaller vessels enlarged pulmonary lobar veins Cardiac silhouette Generalized cardiomegaly, enlarged LA

Thoracic Rads - Abnormal Case #1 – 8 year old neutered male cocker spaniel - coughing Left Heart Failure Mild perihilar edema enlarged pulmonary lobar veins enlarged LA (generalized cardiomegaly) Enlarged LV (elevated trachea) Right Heart Failure enlarged caudal vena cava Generalized cardiomegaly (RV enlargement) (ascites, pleural effusion)

Thoracic Rads - Abnormal Case #1 – 8 year old neutered male cocker spaniel - coughing Diagnosis by echo - DCM

Thoracic Rads - Abnormal Are rads or echo better for detecting congestive heart failure? radiographs Are rads or echo better for detecting enlarged heart chambers? echo

Thoracic Rads - Abnormal Generalized cardiomegaly (all 4 heart chambers enlarged) Dogs Dilated Cardiomyopathy Mitral regurgitation Tricuspid regurgitation Cats Dilated cardiomyopathy anemia

Thoracic Rads - Abnormal Pseudocardiomegaly No significantly enlarged heart chambers Significantly enlarged cardiac silhouette Pericardial effusion Hemorrhage – heart base tumor Right heart failure – modified transudate Infectious pericarditis Idiopathic pericarditis Peritoneopericardial Diaphragmatic Hernia Pericardial fat

Thoracic Rads - Abnormal Case #2 – 15 month Maine coon cat – tachypnea, lethargy Skeletal & cranial abdomen Airways, Lung fields No abnormalities noted Great vessels caudal vena cava somewhat enlarged Smaller vessels Cardiac silhouette Generalized cardiomegaly, apex shifted right 5.1 + 3.8 = 8.9

Thoracic Rads - Abnormal Case #2 – 15 month Maine coon cat – tachypnea, lethargy Heart Failure?? Probably not Diagnosis Echo showed dilation of LV and RV Flea Anemia (PCV 10%)

Thoracic Rads - Abnormal 6.0 + 7.1 = 13.1 Case #3 – 5 year old Maltese – honking cough Skeletal & cranial abdomen & small vessels No abnormalities noted Airways, Lung fields Elevated trachea, compression of left bronchus Focal pulmonary edema Great vessels Bulge at 1:30 on VD Cardiac silhouette Generalized cardiomegaly, apex shifted right, LA enl

Thoracic Rads - Abnormal Case #3 – 5 year old Maltese holosystolic murmur loudest L apex continuous murmur is heard loudest at the left axilla Left Heart Failure pulmonary edema, LA enl, tracheal elevation Airway Cough compression of left bronchus and trachea Bulge at 1:30 on VD, apex shifted right cardiomegaly (R or L or both?)

Thoracic Rads - Abnormal Case #3 – 5 year old Maltese Diagnosis by echo - PDA Right heart normal LISTEN TO THE LEFT ARMPIT!! When the left heart is markedly enlarged, right heart size can be difficult to evaluate

Thoracic Rads - Abnormal Case #4 – 12 year old Mini Poodle - holosystolic murmur L apex Skeletal, cranial abdomen, airways, Lung fields, Great vessels, small vessels No abnormalities noted Cardiac silhouette VHS high if you include LA VHS normal if you exclude LA Huge LA No signs of congestive heart failure

Thoracic Rads - Abnormal Case #4 – 12 year old Mini Poodle - holosystolic murmur L apex Diagnosis Mitral regurgitation Treatment None needed Monitoring Chest rads every 6 months Sooner if respiratory rate while sleeping >40

Thoracic Rads - Abnormal Case #4 – 12 year old Mini Poodle - holosystolic murmur L apex You can have a Huge LA and even LV without CHF CHF is rarely present without enlarged LA

Thoracic Rads - Abnormal Case #5 – 4 year old DSH - Murmur heard on annual – left sternum Skeletal, cranial abdomen, Lung fields, airways, Great vessels, small vessels No abnormalities noted Cardiac silhouette VHS normal Enlarged LA on VD No signs of congestive heart failure Diagnosis by echo - HCM 4 + 3.5 = 7.5

Thoracic Rads - Abnormal Case #5 – 4 year old DSH - Murmur heard on annual – left sternum LA is seen more easily on the VD in cats LA sits more cranial in the cat LA is seen more easily on lateral in dogs VHS usually does not include LA in cats Other chambers need to be enlarged to perceive cardiomegaly on the lateral in cats

Thoracic Rads - Abnormal Case #6 – 10 year old mixed dog - Gagging up white foamy fluid, mitral murmur Skeletal, Cranial abdomen, Great vessels No abnormalities Airways, Lung fields Elevated trachea, compressed left bronchus Perihilar edema Smaller vessels enlarged pulmonary lobar veins Cardiac silhouette VHS 11.5, generalized cardiomegaly, enlarged LA

Thoracic Rads - Abnormal Case #6 – 10 year old mixed dog - Gagging up white foamy fluid, mitral murmur Left Heart Failure Echo diagnosis – severe mitral regurgitation

Thoracic Rads - Abnormal Case #7 – 1 yr old Golden Retriever - Episodes of collapse with exercise Skeletal, Cranial abdomen, Airways, Lung fields, small vessels No abnormalities Cardiac silhouette VHS 9.5, aortic bulge on lateral, enlarged LA No signs of congestive heart failure Echo diagnosis – severe SAS

Thoracic Rads - Abnormal Case #7 – 12 yr old Mixed Terrier - Chronic cough and cyanosis Skeletal, Cranial abdomen, Vessels No abnormalities Airways, Lung fields Pronounced airway pattern Cardiac silhouette VHS 10-10.5, RV enlargement, apex shifted L No heart failure

Thoracic Rads - Abnormal Case #7 – 12 yr old Mixed Terrier - Chronic cough and cyanosis Echo diagnosis RV thickening Pulmonary hypertension Clinical Diagnosis Severe chronic pulmonary disease

Thoracic Rads - Abnormal Case #7 – 12 yr old Mixed Terrier - Chronic cough and cyanosis What does it mean when the apex is shifted right? LV enlargement or generalized cardiomegaly What does it mean when the apex is shifted left? RV enlargement

Thoracic Rads - Abnormal Case #7 – 12 yr old Mixed Terrier - Chronic cough and cyanosis RV enlargement must be moderate to severe to see on rads RA enlargement difficult to appreciate on rads unless severe (cause) TR Lifting of the apex off the sternum on lateral view means RV enlargement

Thoracic Rads - Abnormal 3.75 / 1 = 3.75 Measuring RV enlargement on Lateral View of the Thorax Measure heart long axis Carina to apex Measure heart short axis Widest point perpendicular to long axis Short Axis - Divide Cranial part by Caudal part Cranial is <2.5x Caudal in normal dogs (Cr >2.5x Cd) means RV enlargement

Thoracic Rads - Abnormal Case #8 – 10 month old English Pointer Ejection murmur loudest at left heart base Skeletal, Cranial Abdomen, Airways, Lung fields, small vessels normal Great vessels pulmonary artery enlarged No signs of Congestive Heart Failure

Thoracic Rads - Abnormal Case #8 – 10 month old English Pointer Ejection murmur loudest at left heart base Causes of enlarged MPA (dogs) PS PDA Pulmonary hypertension (lobar aa also enlarged) MPA enlargement Not easily seen on lateral in dogs not readily seen in cats This case – echo diagnosis RV thickening

Thoracic Rads - Abnormal Case #9 – 6 month old poodle with murmur found on physical exam Causes of enlarged pulmonary lobar arteries -Caudal lobar aa should be same width as a rib -cranial lobar aa 0.75x 3rd or 4th rib PDA Pulmonary lobar veins enlarged also Called “pulmonary overcirculation” Pulmonary hypertension Heartworm Disease

Thoracic Rads - Abnormal Case #10 – 5 yr old DSH cat tachypnea Causes of enlarged Caudal vena cava -size varies with respiratory cycle -only severe enlargement is reliably detected -maximum width < length T5 or T6 Right heart failure

Thoracic Rads - Abnormal Case #11 – 2 yr old DSH cat tachypnea Left Heart Failure Right Heart failure Echo diagnosis – hypertrophic cardiomyopathy

Thoracic Rads - Abnormal Case #12 – 6 yr old Westie ADR Clinical diagnosis – severe dehydration Causes of microcardia Severe dehydration Addison’s Disease Pneumothorax (heart lifted off the sternum)

Thoracic Rads - Review Left Heart Failure Pulmonary edema Pleural effusion in cats Pulmonary lobar veins much larger than arteries Enlarged LA Not a sign of heart failure per se But LHF is rarely present without LA enlargement + Enlarged LV Tracheal elevation Cardiomegaly (increased VHS)

Thoracic Rads - Review Right Heart Failure Pleural effusion Can obscure evaluation of the heart, lungs and great vessels Enlarged caudal vena cava Ascites Modified transudate Often concurrent with left heart failure Generalized cardiomegaly (increased VHS)

Thoracic Rads - Review Chronic Bronchitis Increased or mineralized airway pattern Peribronchiolar infiltrates May progress to bronchopneumonia Interstitial pattern Alveolar pattern (air bronchograms) if severe Signs of pulmonary hypertension Enlarged pulmonary artery and lobar aa No signs of heart failure

Thoracic Rads - Review Patent Ductus Arteriosus -left to right shunt (aorta to MPA) -volume expansion + Enlarged pulmonary artery + Pulmonary overcirculation Enlarged pulmonary lobar aa & vv Enlarged descending aorta Enlarged LV Tracheal elevation Increased VHS Enlarged LA + compression left bronchus + pulmonary edema

Thoracic Rads - Review Sub-Aortic Stenosis -pressure overload left side + Enlarged LV Increased VHS Not as marked as volume overload Enlarged ascending aorta Left Heart Failure due to aortic insufficiency is rare

Thoracic Rads - Review Pulmonic Stenosis -pressure overload right side + Enlarged RV Not as marked as volume overload Enlarged MPA Right Heart Failure due to pulmonic insufficiency is rare

Thoracic Rads - Review Ventricular Septal Defect -left to right shunt (LV to RV) -volume expansion + RV enlargement + Pulmonary overcirculation Enlarged pulmonary lobar aa & vv Enlarged LV Tracheal elevation Increased VHS Enlarged LA + compression left bronchus + pulmonary edema

Thoracic Rads - Review Atrial Septal Defect -left to right shunt (LA to RA) -lower pressure differential, so no significant volume expansion + RV enlargement + RA enlargement Enlarged pulmonary lobar aa & vv Heart failure is rare (handout)