veterinary sciences Case Report Left Pulmonary Artery Coarctation Associated with Pneumonia and Pulmonary Hypertension in a Cat Carlotta Valente 1 , Massimiliano Tursi 2 , Helen Poser 1 and Carlo Guglielmini 1, *   Citation: Valente, C.;Tursi, M.; Poser, H.; Guglielmini, C. Left Pulmonary Artery Coarctation Associated with Pneumonia and Pulmonary Hypertension in a Cat. Vet. Sci. 2021, 8, 325. https://doi.org/10.3390/ vetsci8120325 Academic Editor: Bartosz Kempisty Received: 23 November 2021 Accepted: 10 December 2021 Published: 12 December 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Animal Medicine, Production and Health, University of Padova, Viale dell’Università 16, 35020 Padova, Italy; carlotta.valente@unipd.it (C.V.); helen.poser@unipd.it(H.P.) 2 Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, 10095 Grugliasco, Italy; massimiliano.tursi@unito.it * Correspondence: carlo.guglielmini@unipd.it; Tel.: +39-049-8272505 Abstract: A five-month-old European shorthair female kitten was referred because of recurrent episodes of respiratory distress. Results of physical examination, thoracic radiography, and echocar- diography led to a presumptive diagnosis of severe precapillary pulmonary hypertension (PH) and interstitial pneumonia associated with right-sided cardiac remodeling. The cat rapidly died because of respiratory insufficiency. Pulmonary and cardiovascular pathological findings evidenced left pulmonary artery coarctation, severe right-sided cardiac hypertrophy, and bilateral pneumonia. This is the first report of pulmonary artery coarctation associated with pneumonia and PH in a cat. Keywords: congenital heart disease; echocardiography; feline; right ventricular hypertrophy 1. Introduction Obstructions of the pulmonary arteries (PAs) are usually congenital disorders in- volving the pulmonary trunk, the main right or left PA, or the peripheral (i.e., segmental and subsegmental branches) PAs which are rarely observed in cats [1]. Stenosis of the pulmonary trunk or branch PAs are less common than pulmonary valve stenosis or in- fundibular stenosis and include PA interruption, also known as unilateral absence or atresia of the PA, PA stenosis, peripheral or branch PA stenosis, and coarctation of the PA [2]. In humans, the stenosis of the PA branches is classified as four forms: type I occurs as a single constriction of varying length involving the main, left or right PA; type II stenosis occurs at the PA bifurcation and involves the distal end of the main PA and the origins of the left and right PAs; type III stenosis involves multiple segmental PAs at their ostium with concurrent post-stenotic dilatation; and type IV stenosis involves either peripheral segments and central PAs [1]. In cats, only type I and type II forms have been described [3,4]. Pulmonary hypertension (PH) is a pathophysiological disorder characterized by in- creased pressure in the pulmonary arterial vascular bed that can be associated with different cardiovascular and respiratory disorders. In humans, five different types of underlying pathophysiological mechanisms have been recognized for the clinical classification of PH, namely pulmonary arterial hypertension (type 1 PH), PH due to left heart disease (type 2 PH), PH due to lung diseases and/or hypoxia (type 3 PH), chronic thromboembolic PH and other PA obstruction (type 4 PH), and PH due to unclear and/or multifactorial mechanisms (type 5 PH) [5]. In dogs, a recent classification of PH has added an additional type of PH, specific for dogs, namely PH due to parasitic disease (e.g., heartworm disease) considered as type 5 PH [6]. Thus, PH due to unclear and/or multifactorial mechanisms has been reclassified as type 6 [6]. More generally, the hemodynamic clinical classification distinguishes pre-capillary PH, characterized by increased pulmonary artery pressure (PAP) and normal pulmonary artery wedge pressure ([PAWP], i.e., type 1, 3, 4, 5, and 6 PH) from post-capillary PH, in which both PAP and PAWP are increased (i.e., type 2 and 6 PH) [6]. In cats, PH is uncommonly reported and, with the exception of a recent case Vet. Sci. 2021, 8, 325. https://doi.org/10.3390/vetsci8120325 https://www.mdpi.com/journal/vetsci