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390  Section M: Pulmonary Arterial Disorders


              arterial  pressures  using  a  cardiac  catheter  introduced   mation from other species, identification of a treatable
              through  the  jugular  vein.  Such  measurements  are  not   or reversible cause, positive response to such treatment,
              routinely undertaken in cats both because diagnosis and   and milder degrees of pulmonary hypertension should
              treatment  of  an  underlying  cause  appears  to  be  more   be associated with a more favorable prognosis. Since this
              clinically  applicable  and  rewarding,  and  because  per-  is a syndrome comprised of many different causes, the
              forming such measurements may create a risk of sub-  expected outcomes are likewise varied. In human patients
              stantial  iatrogenic  problems  (particularly  as  general   with pulmonary hypertension, mean pulmonary arterial
              anesthesia is generally needed for catheterizing the pul-  pressure, right atrial pressure, and pulmonary vascular
              monary arteries of cats).                          resistance are inversely proportional to survival.


              Treatment                                          REFERENCES
              When  pulmonary  hypertension  exists  in  association   Pulmonary Thromboembolism
              with  a  contributory  or  inciting  cause,  treatment  of
              the cause is indicated first. A common example is con-  Davidson  BL,  Rozanski  EA,  Tidwell AS,  Hoffman AM.  Pulmonary
              gestive  heart  failure,  where  treatment  of  cardiogenic   thromboembolism in a heartworm-positive cat. J Vet Intern Med
                                                                   2006;20:1037–1041.
              pulmonary edema with diuretics and an ACE inhibitor   Dickson BC. Venous thrombosis: On the history of Virchow’s triad.
              may bring improvement or resolution of the pulmonary   Univ Toronto Med J 2004;81:166–171.
              hypertension.                                      Dvorak LD, Preziosi DE, Hitchcock LS. What is your diagnosis? Acute
                 In  the  normal  cat,  pulmonary  vasculature  tone  is   pulmonary thromboembolism secondary to spontaneous death of
                                                                   adult heartworms. J Am Vet Med Assoc 2000;217:180–181.
              maintained as a balance between locally acting vasodila-  Fedullo  PF,  Tapson  VF.  The  evaluation  of  suspected  pulmonary
              tors prostaglandin I 2  and nitric oxide (NO), countered   embolism. N Engl J Med 2003;349:1247–1256.
              by vasoconstricting substances including thromboxane,   Norris CR, Griffey SM, Samii VF. Pulmonary thromboembolism in
              endothelin-I  (ET-I),  and  angiotensin  II  (ATII).   cats:  29  cases  (1987–1997).  J  Am  Vet  Med  Assoc  1999;215:
              Endothelial  dysfunction  in  pulmonary  hypertension   1650–1654.
              contributes  to  smooth  muscle  cell  proliferation   Pouchelon JL, Chetboul V, Devauchelle P, Delisle F, Mai W, Vial V.
                                                                   Diagnosis of pulmonary thromboembolism in a cat using echo-
              (increased ET-I, AT-II, reduced NO), increased produc-  cardiography  and  pulmonary  scintigraphy.  J  Small  Anim  Pract
              tion  of  vasoconstrictor  mediators  including  ET-1  and   1997;38:306–310.
              AT-II, and decreased synthesis of vasodilating substances   Schermerhorn  T,  Pembleton-Corbett  JR,  Kornreich  B.  Pulmonary
              including PGI 2  and NO. Thus, treatment of pulmonary   thromboembolism in cats. J Vet Intern Med 2004;18:533–535.
              hypertension  can  address  either  of  these  two  arms  if   Schober KE, Maerz I. Assessment of left atrial appendage flow velocity
                                                                   and  its  relation  to  spontaneous  echocardiographic  contrast  in
      Pulmonary Arterial Disorders  speculative; published reports of the outcomes of these   Schwarz T, Crawford PE, Owen MR, Störk CK, Thompson H. Fatal
              pulmonary hypertension persists despite control of its
                                                                   89  cats  with  myocardial  disease.  J  Vet  Intern  Med  2006;20:
              inciting cause. In the cat, such treatment applications are
                                                                   120–130.
                                                                   pulmonary fat embolism during humeral fracture repair in a cat.
              treatments are absent in the feline species, likely due to
                                                                   J Small Anim Pract 2001;42:195–198.
              the  rarity  of  this  disorder  in  the  cat  and  the  limited
                                                                 Sottiaux J, Franck M. Pulmonary embolism and cor pulmonale in a
              efficacy  of  treatment  of  pulmonary  hypertension  in
                                                                   cat. J Small Anim Pract 1999;40:88–91.
              many cases. Candidate drugs for treatment of pulmo-
                                                                 Stokol T, Brooks MB, Rush JE, Rishniw M, Erb H, Rozanski E, Kraus
              nary hypertension that persists beyond the treatment of
                                                                   MS, Geltzer AR. Hypercoagulability in cats with cardiomyopathy.
                                                                   J Vet Intern Med 2008;22:546–552.
              its associated or underlying causes may include phos-
              phodiesterase inhibitors such as sildenafil (extrapolated   Thomas JS, Rogers KS. Platelet aggregation and adenosine triphos-
              dose of 1 mg/kg PO q 8 h) or tadalafil, calcium channel   phate secretion in dogs with untreated multicentric lymphoma. J
                                                                   Vet Internal Med 1999;13:319–322.
              blockers  such  as  amlodipine,  angiotensin  converting   Whitley NT, Stepien RL. Defaecation syncope and pulmonary throm-
              enzyme inhibitors such as enalapril or benazepril, endo-  boembolism in a cat. Aust Vet J 2001;79:403–405.
              thelin antagonists such as bosentan, and prostaglandin   Van Vleet JF, Ferrans VJ, Weirich WE. Pathologic alterations in hyper-
              analogs such as beraprost and treprostinil. These treat-  trophic  and  congestive  cardiomyopathy  of  cats.  Am  J  Vet  Res
              ments  represent  future  possibilities,  because  reported   1980;41(12):2037–2048.
              use in feline pulmonary hypertension is absent from the
              veterinary literature.                             Pulmonary Hypertension
                                                                 Connolly  DJ,  Lamb  CR,  Boswood A.  Right-to-left  shunting  patent
              Outcome and Prognosis                                ductus arteriosus with pulmonary hypertension in a cat. J Small
                                                                   Anim Pract 2003;44:184–188.
              The natural history of pulmonary hypertension in the   Kittleson MD, Kienle RD. Small Animal Cardiovascular Medicine. St.
              cat has not been properly documented. Based on infor-  Louis, Mosby, 1998, 125.
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