The effect of sildenafil on pulmonary haemodynamics in a canine model of chronic embolic pulmonary hypertension

Retrospective evaluation of a right heart parameter score in the assessment of precapillary pulmonary hypertension in dogs (2017-2021): 135 cases

OBJECTIVE

To determine if emergency and critical care residents can identify moderate to severe precapillary pulmonary hypertension on cardiologist-obtained cineloops using a pulmonary hypertension score (PHS) and report the interobserver variability of the PHS.

DESIGN

Multicenter, retrospective, case-control study from 2017 to 2021.

SETTING

Private referral center and veterinary teaching hospital.

ANIMALS

One hundred and thirty-five client-owned dogs that underwent diagnostic echocardiography.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records of dogs with stage B1 myxomatous mitral valve disease (MMVD) and dogs diagnosed with precapillary pulmonary hypertension (PCPH) via echocardiograms were reviewed. Dogs were categorized by a cardiologist into 5 groups (normal, B1 MMVD, mild, moderate, and severe PCPH) based on Doppler pulmonary pressure gradients and right heart morphology. Cineloops from each case were subjectively evaluated by emergency and critical care residents for the presence of right atrial and ventricular enlargement, right ventricular hypertrophy, interventricular septal flattening, and pulmonary artery and trunk enlargement to form a composite pulmonary hypertension score out of 8 (PHS8). When available, signs of peritoneal effusion and distention of the caudal vena cava were subjectively assessed to generate a pulmonary hypertension score out of 10 (PHS10). There was excellent discrimination of moderate to severe PCPH versus grouped absent to mild PCPH using PHS8 (area under the receiver operator curve [AUC] [95% confidence interval, CI] = 0.90 [0.84-0.95], P < 0.0001) and PHS10 (AUC [95% CI] = 0.89 [0.81-0.97], P < 0.0001). PHS8 ≥3 was 64% sensitive and 98% specific for moderate to severe PCPH (positive likelihood ratio [LR+] 32, negative likelihood ration [LR-] 0.37). PHS10 ≥ 3.3 was 64% sensitive and 92% specific for moderate to severe PCPH (LR+ 8, LR- 0.39). Interobserver agreement was good to excellent (intraclass correlation coefficient [ICC] = 0.74 [95% CI: 0.66-0.80], n = 135).

CONCLUSIONS

Residents identified moderate to severe PCPH in dogs using PHS on cineloops previously obtained by a cardiologist. The interrater agreement was good to excellent with limited training. Prospective studies to determine if residents can obtain diagnostic images for PHS are warranted.

Comparative Study of Cardiovascular Effects of Selected Pulmonary Vasodilators in Canine Models of Mitral Valve Disease

Previous reports have shown that various oral pulmonary vasodilators are effective against canine pulmonary hypertension (PH). However, no studies have compared their hemodynamic effects. We aimed to compare the hemodynamic effects of 15 µg/kg beraprost sodium, 1.0 mg/kg sildenafil, and their combination, in dogs with experimentally induced mitral regurgitation. This experimental crossover study evaluated the hemodynamic and functional effects of oral pulmonary vasodilators by application of right-sided heart catheterization and echocardiography. Beraprost significantly decreased pulmonary and systemic vascular resistance. Additionally, beraprost increased right-ventricular stroke volume and left-ventricular cardiac output without worsening left-heart size and left-atrial pressure. The pulmonary vasodilatory effects of sildenafil were stronger, and its systemic vasodilatory effects were weaker than those of beraprost. However, sildenafil significantly increased the left-ventricular volume, left-atrial pressure indicator, and right-ventricular cardiac output. Combination therapy resulted in the strongest pulmonary and systemic vasodilating effects without worsening the left-heart size and left-atrial pressure indicators. Both beraprost and sildenafil were effective against canine PH; however, sildenafil was associated with the risk of worsening left-heart loading. Combination therapy with beraprost and sildenafil synergistically dilated pulmonary and systemic vessels, indicating a more potent treatment option for severe PH cases.

Beraprost Sodium for Pulmonary Hypertension in Dogs: Effect on Hemodynamics and Cardiac Function

Simple Summary

Pulmonary hypertension is a potentially life-threatening disease among dogs that is characterized by increased pulmonary arterial pressure and pulmonary vascular resistance. In veterinary medicine, a phosphodiesterase-5 inhibitor such as sildenafil is the most common drug used to treat pulmonary hypertension. However, the availability of sildenafil is limited because of its high cost, difficulty in obtaining the drug in some areas, and potential inter-individual variability in the response to sildenafil therapy. Beraprost sodium is one of the most common drugs used to treat pulmonary hypertension in humans. However, little is known about its efficacy in dogs with pulmonary hypertension. In this study, beraprost sodium showed significant pulmonary and systemic vasodilation without any adverse effects in sixteen dogs with pulmonary hypertension. Additionally, echocardiographic improvements in cardiac function and pulmonary and systemic circulation were observed. These results emphasize the potential efficacy of beraprost sodium in treating canine pulmonary hypertension.

Abstract

Pulmonary hypertension (PH) is a fatal condition that affects many dogs. In humans, PH is often treated with beraprost sodium (BPS). However, the effectiveness of BPS for canine PH has not been established. This study aimed to evaluate the clinical and cardiovascular response of BPS in canine patients with PH of various causes. Sixteen dogs with PH (post-capillary PH, n = 8; pre-capillary PH, n = 8) were included. BPS was continuously administered twice daily at 15 µg/kg. All dogs underwent echocardiography, including speckle-tracking analysis and blood pressure measurement, before and after BPS administration. Continuous BPS administration (range: 13.2–22.0 µg/kg) significantly decreased the pulmonary and systemic vascular impedance and increased left and right ventricular myocardial strain. In dogs with post-capillary PH, BPS administration caused no significant worsening of the left atrial pressure indicators. No side effects of BPS were observed in any dog. BPS also improved cardiac function and pulmonary circulation through pulmonary vasodilation, suggesting that BPS may be an additional treatment option for canine PH of various causes. Particularly, BPS increased left ventricular function and systemic circulation without worsening the left heart loading condition in dogs with post-capillary PH.

Investigation of Beraprost Sodium on Cardiac Function and Hemodynamics in Canine Models of Chronic Pulmonary Hypertension

Pulmonary hypertension (PH) is a life-threatening disease in dogs characterized by increased pulmonary arterial pressure (PAP) and/or pulmonary vascular resistance. No study has evaluated the utility of Beraprost sodium (BPS) in dogs with PH. This study aimed to evaluate the effect of BPS on cardiac function and hemodynamics and examine the optimal dose of BPS in canine models of chronic embolic PH. In this prospective crossover study, three doses of BPS (5, 15, and 25 μg/kg, twice a day) were examined in eight canine models of chronic embolic PH. All model dogs underwent invasive PAP measurement, echocardiography, and non-invasive systemic blood pressure measurement before and after continuous administration of oral BPS for 1 week. No side effects of BPS were observed in any dog during the study. All doses of BPS significantly decreased systolic PAP and pulmonary vascular impedance. Additionally, systemic vascular impedance significantly decreased with 15 and 25 μg/kg of BPS. The right ventricular stroke volume and longitudinal strain significantly decreased with all doses of BPS. The left ventricular stroke volume and circumferential strain decreased with 15 μg/kg BPS. BPS was well-tolerated in this study. A dose-dependent vasodilating effect on pulmonary vessels was observed in canine models of chronic PH. Additionally, 15 μg/kg BPS showed a balanced vasodilating effect on systemic and pulmonary vessels. Furthermore, with a decrease in systemic and pulmonary vascular impedance, the left and right ventricular functions were significantly improved. Our results suggest that BPS may be useful in the treatment of canine PH.

Tricuspid valve chordal rupture in a dog with pulmonary hypertension

Background:

Rupture of the chordae tendineae of the tricuspid valve is rare in dogs. We report the case of a dog with tricuspid valve chordal rupture secondary to pulmonary hypertension.

Case Description:

A 7.7-kg, 13-year-old neutered male Pekingese on annual heartworm prevention presented with respiratory distress. The patient received a diagnosis of pulmonary hypertension and received medical treatment. However, the patient re-presented 405 days post-diagnosis with dyspnea and an increased abdominal circumference. Transthoracic echocardiography showed ruptured chordae tendineae of the tricuspid valve, and abdominal ultrasound identified significant ascites associated with worsening right congestive heart failure. The patient improved after draining ascitic fluid and extra medical treatment, but was released with poor prognosis.

Conclusion:

Ruptured chordae tendineae of the tricuspid valve should be considered in patients with pulmonary hypertension.