Pulmonary Pulmonary ThromboembolismThromboembolism

Emily S. Southward DVMEmily S. Southward DVMUniversity of Missouri – Columbia University of Missouri – Columbia

Veterinary Medical Teaching Veterinary Medical Teaching HospitalHospital

DefinitionDefinition

Pulmonary thromboembolismPulmonary thromboembolism– One clot or many clots that form at One clot or many clots that form at

distant sites and lodge in the pulmonary distant sites and lodge in the pulmonary vasculature.vasculature.

Pulmonary artery thrombusPulmonary artery thrombus– Clots that form in the pulmonary Clots that form in the pulmonary

vasculature.vasculature. Clots can partially or fully occlude Clots can partially or fully occlude

pulmonary vessels.pulmonary vessels.

Virchow’s TriadVirchow’s Triad

Venous stasis.Venous stasis. Injury or abnormalities to the vessel Injury or abnormalities to the vessel

wall.wall. Alterations in coagulation properties.Alterations in coagulation properties.

Venous StasisVenous Stasis

Accumlation of activated Accumlation of activated procoagulants.procoagulants.– ImmobilizationImmobilization– Inadequate cardiac pump.Inadequate cardiac pump.

Promotes thrombus formation.Promotes thrombus formation.

Vessel Wall InjuryVessel Wall Injury

Acute or chronic injury to vessel Acute or chronic injury to vessel endothelium.endothelium.

Leads to activation of platelets and Leads to activation of platelets and clotting cascade.clotting cascade.

Promotes thrombus formation.Promotes thrombus formation.

Vessel InjuryVessel Injury

Platelet AdhesionPlatelet Adhesion

AggregationAggregation

Alternations in CoagulationAlternations in Coagulation

Increase in procoagulant factors.Increase in procoagulant factors.– By trauma to vascular wall or By trauma to vascular wall or

extravascular tissues.extravascular tissues.– Releases tissue thromboplastin and Releases tissue thromboplastin and

phospholipid.phospholipid.– Leads to formation of prothrombin Leads to formation of prothrombin

activator.activator.– Prothrombin Prothrombin Thrombin Thrombin

Alterations in CoagulationAlterations in Coagulation

Decrease in anticoagulant factors.Decrease in anticoagulant factors.– ThrombomodulinThrombomodulin– Antithrombin IIIAntithrombin III– HeparinHeparin– AlphaAlpha22-Marcoglobulin-Marcoglobulin– PlasminPlasmin

Leads to hypercoagulable state by Leads to hypercoagulable state by formation of thrombin.formation of thrombin.

Thrombosis FormationThrombosis Formation

Platelet nidus at site of injury.Platelet nidus at site of injury. Growth by aggregation of platelets Growth by aggregation of platelets

and fibrin.and fibrin. Activation of clotting cascade.Activation of clotting cascade. Larger growth to a red fibrin Larger growth to a red fibrin

thrombus.thrombus. Thrombus fractures and embolizes to Thrombus fractures and embolizes to

other areas of the body.other areas of the body.

Predisposing Factors or Diseases Predisposing Factors or Diseases for Development of PTEfor Development of PTE

Hypercoagulable stateHypercoagulable state– Nephrotic syndromeNephrotic syndrome– ImmobilizationImmobilization– AmyloidosisAmyloidosis– Early DICEarly DIC– HyperadrenocorticismHyperadrenocorticism

Capillary fragilityCapillary fragility Activation of clotting cascade.Activation of clotting cascade.

Predisposing Factors or Diseases Predisposing Factors or Diseases for Development of PTEfor Development of PTE

Hypercoagulable stateHypercoagulable state Capillary fragilityCapillary fragility

– Diabetes MellitusDiabetes Mellitus– Immune–mediated hemolyitc anemiaImmune–mediated hemolyitc anemia– SepsisSepsis– HyperadrenocorticismHyperadrenocorticism

Activation of clotting cascade.Activation of clotting cascade.

Predisposing Factors or Diseases Predisposing Factors or Diseases for Development of PTEfor Development of PTE

Hypercoagulable stateHypercoagulable state Capillary fragilityCapillary fragility Activation of clotting cascade.Activation of clotting cascade.

– SepsisSepsis– Pneumonia/pyothoraxPneumonia/pyothorax– Heartworm diseaseHeartworm disease– SurgerySurgery– Bacterial endocarditisBacterial endocarditis– NeoplasiaNeoplasia

Consequences of PTEConsequences of PTE

Respiratory.Respiratory.– Increased alveolar dead space.Increased alveolar dead space.– Hyperventilation.Hyperventilation.– Hypoxemia.Hypoxemia.– Ventilation/perfusion inequality.Ventilation/perfusion inequality.– Intrapulmonary shunts.Intrapulmonary shunts.

Normal AlveolusNormal Alveolus

Increased Alveolar Dead SpaceIncreased Alveolar Dead Space

HypoxemiaHypoxemia

Results from ventilation-Results from ventilation-perfusion inequality, physiologic perfusion inequality, physiologic shunting and increased dead shunting and increased dead space. space.

Intrapulmonary ShuntsIntrapulmonary Shunts

Blood that has not been to areas of Blood that has not been to areas of ventilated lung and enters systemic ventilated lung and enters systemic circulation without gas exchange circulation without gas exchange taking place. taking place.

Poorly oxygenated blood enters the Poorly oxygenated blood enters the arterial system lowering the PaOarterial system lowering the PaO22..

Not responsive to oxygen therapy.Not responsive to oxygen therapy.

Ventilation/Perfusion InequalityVentilation/Perfusion Inequality

V/Q inequality occurs when V/Q inequality occurs when distribution of blood is altered to the distribution of blood is altered to the alveoli.alveoli.

OO22 increase in the alveoli and CO increase in the alveoli and CO22 decreases.decreases.

Hemodynamic ChangesHemodynamic Changes

Increase in pulmonary vascular Increase in pulmonary vascular resistance.resistance.

Increased afterload to the right Increased afterload to the right heart.heart.

Can lead to circulatory collapse and Can lead to circulatory collapse and shock.shock.

Clinical SignsClinical Signs

Not pathognomonic.Not pathognomonic.– Dyspnea.Dyspnea.– Tachypnea.Tachypnea.– Hemoptysis.Hemoptysis.– Tachycardia.Tachycardia.– Hypoxemia.Hypoxemia.– Sudden death. Sudden death.

DiagnosisDiagnosis

CBC/Biochemistry results reflect CBC/Biochemistry results reflect primary disease process.primary disease process.

Hypoxemia common but 10% of Hypoxemia common but 10% of patients are normal.patients are normal.

Thoracic radiographs can be normal Thoracic radiographs can be normal and inconclusive.and inconclusive.

LaRue MJ and Murtaugh RJ. Pulmonary LaRue MJ and Murtaugh RJ. Pulmonary Thromboembolism in Dogs:47 cases (1986-87). Thromboembolism in Dogs:47 cases (1986-87). J J Amer Vet Med Assoc. Amer Vet Med Assoc. 1990 Nov. 15;197(1):1368-1990 Nov. 15;197(1):1368-1372.1372.

Johnson LR Johnson LR et al. et al. Pulmonary Thromboembolism in Pulmonary Thromboembolism in 29 dogs:1985-1995 29 dogs:1985-1995 J Vet Intern Med. J Vet Intern Med. 1999 1999 Jul;13(4):338-345.Jul;13(4):338-345.

Flükiger MA and Gomez JA. Radiographic Findings Flükiger MA and Gomez JA. Radiographic Findings in Dogs with Spontaneous Pulmonary Thrombosis in Dogs with Spontaneous Pulmonary Thrombosis or Embolism. or Embolism. Veterinary Radiology, Veterinary Radiology, Vol.25,No.3 Vol.25,No.3 124-131.124-131.

Advanced DiagnosticsAdvanced Diagnostics

Pulmonary scintigraphy Pulmonary scintigraphy Pulmonary angiography.Pulmonary angiography.

Pulmonary ScintigraphyPulmonary Scintigraphy

NoninvasiveNoninvasive Aids in diagnosis of PTE but not Aids in diagnosis of PTE but not

definitive.definitive. Two types- ventilation and perfusion Two types- ventilation and perfusion

scans.scans.

Perfusion ScanPerfusion Scan

Performed first.Performed first. Normal study rules Normal study rules

out PTE.out PTE. Radionuclide-Radionuclide-

labelled, labelled, macroaggregated macroaggregated albumin in albumin in peripheral vein.peripheral vein.

Ventilation ScanVentilation Scan

Inhaled radioactive Inhaled radioactive inert gas-senon-inert gas-senon-133 or technetium-133 or technetium-99m.99m.

Patient under Patient under general anesthesia.general anesthesia.

Normal in PTE.Normal in PTE.

Ventilation/Perfusion ComboVentilation/Perfusion Combo

With PTE the With PTE the ventilation scan ventilation scan would be normal would be normal and the perfusion and the perfusion scan abnormal.scan abnormal.

Suggestive of PTE.Suggestive of PTE.FF

Picture from Picture from WWW.bschsys.org/DiagnositcImaging/nucmd/WWW.bschsys.org/DiagnositcImaging/nucmd/htmhtm

Normal Human Perfusion ScanNormal Human Perfusion Scan

Abnormal Human Perfusion Abnormal Human Perfusion ScanScan

Pulmonary AngiographyPulmonary Angiography

Performed if definitive diagnosis or Performed if definitive diagnosis or exclusion of PTE is required.exclusion of PTE is required.

Requires sedation or general Requires sedation or general anesthesia.anesthesia.

Greater risks.Greater risks. Intraluminal filling defect and sharp Intraluminal filling defect and sharp

cutoff are diagnostic for PTE.cutoff are diagnostic for PTE.

Pulmonary EmbolusPulmonary Embolus

Human lung.Human lung. Arrow indicates Arrow indicates

abrupt termination abrupt termination of a pulmonary of a pulmonary artery.artery.

Www.brighamrad.Harvard.edu/cases/Www.brighamrad.Harvard.edu/cases/bwh/images.bwh/images.

TreatmentTreatment

Oxygen therapy.Oxygen therapy. Heparinization 200-300 units/kg Heparinization 200-300 units/kg

subcutaneously every 8 hours.subcutaneously every 8 hours. Streptokinase or TPA.Streptokinase or TPA. Mechanical ventilation.Mechanical ventilation. Long term- warfarin therapy.Long term- warfarin therapy.

MonitoringMonitoring

Clotting times- want to maintain PTT Clotting times- want to maintain PTT at 1.5-2.5 times normal or and ACT at 1.5-2.5 times normal or and ACT at 1.2-1.4 times normal.at 1.2-1.4 times normal.

Serial arterial blood gas analysis.Serial arterial blood gas analysis. Respiratory rate.Respiratory rate. Central venous pressure.Central venous pressure. All other basic monitoring.All other basic monitoring.

Complications Of TherapyComplications Of Therapy

Hemorrhage most common. Hemorrhage most common. Not predictable. Not predictable. Protamine therapy indicated with Protamine therapy indicated with

hemorrhage due to heparin.hemorrhage due to heparin. Vitamin K or fresh-frozen plasma in Vitamin K or fresh-frozen plasma in

warfarin therapy.warfarin therapy.

PrognosisPrognosis

Guarded.Guarded. Improves with early detection and Improves with early detection and

treatment.treatment. Improves each day the patient Improves each day the patient

survives.survives. At risk for more emboli.At risk for more emboli.

UMC VMTH CasesUMC VMTH Cases

Three in data base.Three in data base.– SadieSadie– MagnumMagnum– KokoKoko

Sadie BaileySadie Bailey

8-year-old FS mixed breed dog.8-year-old FS mixed breed dog. Presented for weight loss, anemia, Presented for weight loss, anemia,

and anorexia.and anorexia. Weak and lethargic on presentationWeak and lethargic on presentation Hemoabdomen, thrombocytopenia, Hemoabdomen, thrombocytopenia,

and neutrophilia with left shift.and neutrophilia with left shift. Developed severe dyspnea and Developed severe dyspnea and

ventricular tachycardia.ventricular tachycardia.

Sadie’s Thoracic FilmsSadie’s Thoracic Films

Sadie’s Thoracic FilmsSadie’s Thoracic Films

Sadie’s NecropsySadie’s Necropsy

Hepatocellular carcinomaHepatocellular carcinoma Adrenocortical hyperplasiaAdrenocortical hyperplasia Pulmonary thrombois – most lobar Pulmonary thrombois – most lobar

branches effected.branches effected. Renal infarction.Renal infarction.

Magnum MeeksMagnum Meeks

8-year-old MC doberman pinscher8-year-old MC doberman pinscher Presented for dyspnea of two days Presented for dyspnea of two days

duration.duration. Protein losing nephropathy.Protein losing nephropathy.

Magnum’s Thoracic FilmsMagnum’s Thoracic Films

Magnum’s Thoracic FilmsMagnum’s Thoracic Films

Koko WesterhoffKoko Westerhoff

12-year-old FS dachshund.12-year-old FS dachshund. Presented for lethargy, anorexia, Presented for lethargy, anorexia,

tachypnea, and possible CHF.tachypnea, and possible CHF. History includes diabetes mellitus, History includes diabetes mellitus,

IVDD and cataracts.IVDD and cataracts. PE- Increased BV lung sounds, mild PE- Increased BV lung sounds, mild

crackles, tachycardia, and left crackles, tachycardia, and left systolic murmur.systolic murmur.

Koko’s Thoracic FilmsKoko’s Thoracic Films

Koko’s Thoracic FilmsKoko’s Thoracic Films

Koko’s Pefusion ScintigraphyKoko’s Pefusion Scintigraphy

Koko’s Pefusion ScintigraphyKoko’s Pefusion Scintigraphy

Koko’s NecropsyKoko’s Necropsy

Muliple small thrombi in the Muliple small thrombi in the pulmonary vasculature.pulmonary vasculature.

CardiomegalyCardiomegaly

ThanksThanks

Dr. MannDr. Mann Dr. DodamDr. Dodam Dr. LattimerDr. Lattimer Dr. KunzDr. Kunz

Questions?Questions?