Evaluation of pulmonary hypertension and clinical status in dogs with heartworm by Right Pulmonary Artery Distensibility Index and other echocardiographic parameters

Abstract

BackgroundPulmonary hypertension (PH) is a frequent and severe phenomenon in heartworm disease caused by Dirofilaria immitis, mainly caused by intimal proliferation of the arteries and pulmonary thromboembolisms. Transthoracic echocardiography is the method of choice for diagnosing PH in dogs although the diagnosis is often based on indirect and subjective parameters. The Right Pulmonary Artery Distensibility Index (RPAD Index) is a method that has been recently validated to estimate the presence and severity of PH in heartworm-infected dogs. This study compared some echocardiographic parameters commonly used to estimate PH in 93 dogs infected by D. immitis and evaluated the impact of the parasite burden, microfilaremia, sex or origin of the dog (client-owned/shelter).ResultsNone of the studied echocardiographic variables seemed useful in the estimation of the evaluated clinical aspects, except for the PA/Ao ratio for parasite burden. The RPAD Index was determined in 88 of the dogs; of these, 70.4% had PH (mild: 37.5%, moderate: 19.3%, severe: 13.6%). This Index showed non-significant differences according to microfilaremia, sex, origin or parasite burden. Symptomatic dogs showed PH more often and displayed more severe PH, in addition the presence of symptoms was greater among dogs with high burden; on the other hand 64.4% of asymptomatic dogs had some degree of PH according to the RPAD Index. Apart from the PA/Ao ratio, the other evaluated echocardiographic variables were not useful in evaluating of the hypertensive status of the heartworm-infected dog compared to the RPAD Index.ConclusionsThe estimation of most common indirect parameters is not useful in predicting PH in heartworm-infected dogs. The results confirm the RPAD Index as an objective and supportive test in the monitoring and evaluation of PH in the heartworm-infected dog, and show a potential diagnostic value for the detection of PH in asymptomatic animals.

ACVIM consensus statement guidelines for the diagnosis, classification, treatment, and monitoring of pulmonary hypertension in dogs

“…151 However, as this is a heterogeneous syndrome with multiple defects, clinical manifestations could also be classified under chronic obstructive airway disorders. j Dirofilaria and Angiostrongylus have been associated with endarteritis, 17,25,35,41,44,50,51,66,[127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142] PE/PT/PTE, 147 inflammatory pulmonary parenchymal disease, [143][144][145][146] or all, as their mechanisms of PH. k In humans, hematologic disorders (eg, certain types of anemia, myeloproliferative disorders, and splenectomy), systemic disorders with lung involvement (eg, sarcoidosis, Langerhans cell histiocytosis, vasculitis, etc), metabolic disorders (disorders of impaired cell metabolism, thyroid disease), and other diseases not well classified in another group (eg, compressive lesions such as lymphadenopathy, tumor or fibrosing mediastinitis obstructing the pulmonary arteries, etc) comprise the multifactorial, unclear mechanism group, or both.…”

“… Dirofilaria and Angiostrongylus have been associated with endarteritis, PE/PT/PTE, inflammatory pulmonary parenchymal disease, or all, as their mechanisms of PH.…”

Preventive efficacy of six monthly oral doses of Simparica Trio®, Heartgard® Plus, and Interceptor® Plus against a macrocyclic lactone-resistant strain (ZoeLA) of heartworm (Dirofilaria immitis) in dogs

“…Pulmonary arterial disease is ubiquitous in infected dogs, with adult worms beginning to cause traumatic arterial damage days after reaching the caudal pulmonary arteries [ 17 , 18 ]. Although many infected dogs show no clinical signs, infections with higher worm burdens tend to result in more significant clinical disease [ 17 ], including congestive heart failure due to pulmonary hypertension [ 19 , 24 ] and increased risk of fatal caval syndrome [ 1 , 5 ].…”

“…Five of the six dogs treated with Simparica Trio had heartworms (one had none), with a geometric mean of 1.0 worms (range, 0-3). All six dogs treated with Heartgard Plus had heartworms with a geometric mean of 32.5 worms (range, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], and all six dogs treated with Interceptor Plus had heartworms with a geometric mean of 22.8 worms (range, 10-34).…”

Dog heartworm disease is here to stay: The most important aspects of clinical relevance

“…Among other echocardiographic parameters, MPA/AO and the RPAD Index were proven to be useful in evaluating the hypertensive status in heartworm-infected dogs. Furthermore, the RPAD Index has potential diagnostic value for the detection of PH in asymptomatic animals (Serrano-Parreño et al, 2017;Venco et al, 2014).…”