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J Vet Clin 2023; 40(2): 130-134

https://doi.org/10.17555/jvc.2023.40.2.130

Published online April 30, 2023

Double-Chambered Right Ventricle in an Old Standard Poodle Dog

Yunho Jeong1 , Yoonhwan Kim1 , Eunchan Lee2 , Ju-Hyun An3 , Sooyoung Choi2 , Jin-Young Chung1 , Jin-Ok Ahn1,*

1Department of Veterinary Internal Medicine and Institute of Veterinary Science, College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea
2Department of Veterinary Diagnostic Imaging, College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea
3Department of Emergency and Critical Care Medicine, College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea

Correspondence to:*joahn@kangwon.ac.kr

Received: February 3, 2023; Revised: March 20, 2023; Accepted: April 11, 2023

Copyright © The Korean Society of Veterinary Clinics.

A 12-year-old Standard Poodle presented with intermittent weakness and occasional dyspnea at the Veterinary Medicine Teaching Hospital of Kangwon National University. A grade of 4 out of 6 systolic murmur with an irregular tachycardic rhythm was auscultated on both sides of the chest. Systolic blood pressure was 140 mmHg. Panting was noticed in the hospital, but there was no crackle sound. Blood analysis revealed mild increases in liver panel levels (alanine aminotransferase 149 [reference interval, 19-70] U/L; and alkaline phosphatase, 185 [reference interval, 15-127] U/L) and severe increases in cardiac biomarker levels (n-terminal pro-brain natriuretic peptide, 4169 [reference interval, 50-900] pmol/L; and cardiac troponin I, 0.22 [reference interval, 0.03-0.12] ng/mL). On electrocardiography, irregularly irregular supraventricular tachycardic rhythm with an f-wave and no distinct p-wave was observed. Generalized cardiomegaly with an enlarged right atrium and left ventricle was confirmed on thoracic radiography. Moreover, hepatomegaly and an enlarged caudal vena cava were observed. Echocardiographic evaluation revealed a fibromuscular diaphragm in the right ventricle. Because of the obstructive lesion in the right ventricle, the right atrium and ventricle were enlarged (right atrial area index, 38.82 cm2/m2 [reference interval, 4.2-10.2 cm2/m2]; right ventricle end-diastolic area index, 14.152 cm2/m2 [reference interval, 4.9-10.92 cm2/m2]). Accordingly, the patient was diagnosed with double- chambered right ventricle (DCRV). Pimobendan, furosemide, enalapril, diltiazem, and S-adenosylmethionine (SAMe) were prescribed, and all symptoms were relieved. DCRV is a right-sided congenital heart defect resembling pulmonic valve stenosis. If symptoms are not severe, medical therapy can be facilitated without surgery or the balloon dilation.

Keywords: double-chambered right ventricle, congenital heart disease, pulmonary stenosis, right-sided heart failure, standard poodle dog

Double-chambered right ventricle (DCRV) is an uncommon congenital heart disease in humans and dogs (9,12). Anomalous muscle bands or endogenous trabecular hypertrophy may cause abnormal separation (9). Two chambers exist: an inflow chamber with high pressure, and an outflow chamber with low pressure (8-11). In humans, DCRV is characterized by pressure gradients of over 20 mmHg between the two chambers and is frequently associated with other anomalies, including Ebstein’s anomaly, membranous ventricular septal defect, and double-outlet right ventricle (9). However, such association has not been identified in dogs.

The obstruction creates variable sized orifices for the two chambers (1). This pressure overload creates the same pathophysiologic changes within the heart as pulmonic valvular stenosis (1,3,10,18). Also, the high pressure chamber can lead to tricuspid insufficiency without any structural tricuspid valvular disease (1). Using echocardiography to diagnose this anomaly by confirming the anomalous muscle bands or turbulent flow within the right ventricle (1). We herein present a case of DCRV in an old, Standard Poodle dog having low pressure gradient between two chambers.

A 12-year-old, 30-kg, intact male Standard Poodle was presented to the Veterinary Medicine Teaching Hospital of Kangwon National University for intermittent weakness, dyspnea under stressful situations, and nocturnal cough. He had no other previous illnesses except for otitis externa.

On physical examination, the dog had a slightly increased heart rate, varying from 160 to 220 bpm, with an irregular rhythm. A grade IV/VI systolic murmur was auscultated on both chest walls. Femoral pulse quality was normal, but pulse deficits were present. Systolic blood pressure was 130 mmHg. The capillary refill time was normal (<2 s), with a pink mucous membrane color. No remarkable lung sounds were noted. Blood analysis revealed mild elevations in liver panel levels (alanine aminotransferase, 149.77 U/L [reference interval, 19-70] U/L; and alkaline phosphatase, 185 [reference interval, 15-127]) and significant elevations in cardiac biochemical marker levels (cardiac troponin I, 0.22 ng/mL [reference interval, 0.03-0.12]; and N-terminal pro-brain natriuretic peptide 4169.5 pmol/L [reference interval, 0-900], vCheck canine NT-proBNP [V200 Analyzer, Bionote, Korea]). Since there was an irregularity in cardiac rhythm, electrocardiography was performed. Irregularly irregular tachyarrhythmia without significant p-waves was confirmed, and f-waves were present. The QRS complex was narrow (<0.07 s) and had a normal morphology. Based on this irregularity with f-waves, atrial fibrillation was diagnosed (Fig. 1). Thoracic and abdominal radiography revealed marked generalized cardiomegaly (vertebral heart score, 12.6 v) (Fig. 2A, B) and mild hepatomegaly (liver length: T11 vertebral length ratio, 7.71) (Fig. 2C). Two-dimensional echocardiographic examination revealed a severely enlarged right ventricle and atrium (Fig. 3A). A thin membrane dividing the right ventricle before the right ventricular outflow tract was observed (Fig. 3B). The proximal chamber ventricular free wall showed focal concentric hypertrophy with eccentric changes in the rest of the ventricular wall (Fig. 3C). Moreover, there was turbulent flow along the obstruction area (Fig. 3D). However, it was not possible to measure flow velocity across the obstructed area. The estimated pressure gradient between the two chambers was 18 mmHg. Severe tricuspid regurgitation with a velocity of 2.75 m/s due to right chamber dilation was confirmed by color and continuous-wave Doppler echocardiography (Fig. 3E, F). Pulmonic valve degeneration or regurgitation was not observed. Right ventricular systolic function decreased (fractional area change [FAC], 28.6% [reference interval, 33.9-56.3%]) (17). There was no other evidence of pulmonary hypertension other than tricuspid regurgitation.

Figure 1.Electrocardiography (ECG) results of the patient. ECG reveals irregularly irregular rhythm without noticeable p-waves. F-waves can also be identified. Accordingly, atrial fibrillation can be diagnosed.

Figure 2.Radiographs from the dog with double-chambered right ventricle (DCRV). Generalized cardiomegaly (vertebral heart score, 12.6 v = 6.4 [L] + 6.2 [S]) with increased sternal contact can be observed in thoracic radiographs (A, B). Abdominal radiograph shows hepatomegaly (liver length: T11 vertebral length ratio, 7.71) (C).

Figure 3.Echocardiographic findings. A severely enlarged right heart can be observed on the right parasternal long axis 4-chamber view (A). A thin fibromuscular structure dividing the right ventricle can be observed (white arrow) in the right parasternal short axis view (B). There is focal muscle hypertrophy before the obstructive lesion in the right parasternal short axis view. Wall thickness is 20.8 mm (C). Color Doppler echocardiography revealed turbulent flow along the obstructive area in the mid-right ventricle. Unfortunately, we were unable to evaluate flow velocity across the fibromuscular region, though estimated pressure gradient was 18 mmHg (D). Color Doppler echocardiography at the right parasternal long-axis 4 chamber view shows severe tricuspid regurgitation due to inadequate coaptation of tricuspid leaflets (E). The regurgitant flow velocity is 2.75 m/s, and the peak pressure gradient is 30.3 mmHg on continuous wave Doppler echocardiography at the left apical 4 chamber view (F). AO, aorta; LA, left atrium; LV, left ventricle; MPA, main pulmonary artery; PV, pulmonic valve; RA, right atrium; RV, right ventricle; RVO, right ventricular outflow.

Accordingly, the patient was diagnosed with DCRV, right-sided congestive heart failure, and atrial fibrillation. To control the symptoms and mild hepatomegaly, 1 mg/kg (PO q 12 h) of furosemide (Lasix; HANDOK, Seoul, Korea), 0.25 mg/kg (PO q 12 h) of pimobendan (Vetmedin; Boehringer Ingelheim, Ingelheim am Rhein, Germany), 0.5 mg/kg (PO q 12 h) of enalapril (Enalapril Maleate; CMG pharmaceutical, Seoul, Korea), 0.5 mg/kg (PO q 12 h) of diltiazem (Herben; HKinno.N, Cheongju, Korea), 0.5 mg/kg (PO q 12 h) of omeprazole (Omed; SK chemicals, Seongnam, Korea), and SAMe (S-adenosylmethionine; Zentonil; Vetoquinol, Lure, France) were prescribed.

After treatment, according to the owner, the dog experienced no further weakness or dyspnea. A physical examination performed again revealed an irregular heart rate of 140-160 bpm. Atrial fibrillation was still present on electrocardiography; however, the average heart rate in the hospital was 130 bpm. Radiographic evaluation showed slightly decreased cardiac size (Fig. 4A) and reduced hepatomegaly (vertebral heart score, 11.8 v; and liver length: T11 vertebral length ratio, 6.82) (Fig. 4B). Echocardiography confirmed elevated right ventricular systolic function (FAC, 44.2%). Overall, the results were good and the same medications were prescribed.

Figure 4.Radiographs after 3 months of medical therapy. Generalized cardiomegaly is slightly decreased in the thoracic radiograph (vertebral heart score, 11.8 v = 5.6 v [L] + 6.2 v [S]) (A). Abdominal radiograph shows reduced hepatomegaly (liver length: T11 vertebral length ratio, 6.8) (B).

DCRV is one of the most uncommon congenital heart diseases in dogs, with a known prevalence of 1%-1.8% among dogs with congenital heart disease (2,12). The two main classifications of this congenital anomaly can be made according to the differences in the structure that divides the right ventricle (13). Type 1 is caused by anomalous muscle bands, whereas type 2 is caused by trabecular hypertrophy (13). Moreover, the obstructive lesion is described as “high” when it is close to the pulmonary valve and “low” when it is close to the apex (4,5). There have been some discussions regarding the terminology used to name this anomaly. Primary infundibular stenosis, mid-ventricular stenosis, and DCRV are the nomenclatures used (1). These can be distinguished based on the location and characteristics of the obstruction. The cardiac remodeling and hemodynamics of DCRV are influenced by pressure overload in the right ventricle, resulting in severe right-sided congestive heart failure, eventually like pulmonary stenosis (3,10,18). However, some differences exist between these congenital diseases, including breed prevalence and treatment implications. DCRV is usually associated with other malformations (2,9,12); however, in this case, only isolated DCRV was observed.

Treatment options to control this mid-ventricular obstruction include surgical resection, catheter-based procedures, and conservative medical therapy (10,18,20). Of these modalities, surgery is the most successful (10,15,18,19). However, availability and affordability are major obstacles for this approach (10,15). Balloon dilation of the obstruction has been tried in several cases (6,10,14,15,20), though not all cases showed the best results. Some patients have favorable long-term results (6,20). The medical management of DCRV is almost the same as that of pulmonic stenosis (9,18). To minimize cardiac workload and excessive oxygen consumption, beta-blockers are commonly prescribed when there is no evidence of congestion.

Few studies have reported DCRV in dogs, most of whom die at a young age (3,12). Symptoms are progressive, resulting exercise intolerance, cough, cyanosis, panting, syncope, and sudden death in humans, dogs, and cats (3,7). However, if patients undergo surgery or balloon dilation, the prognosis is good (10,20). In this case, the patient was diagnosed at 12 years of age without significant congestive signs. The pressure gradient across the ostium was believed to be 18 mmHg, which is much less than that in other cases (3,6,10,20). In humans, when a patient does not present with significant coexisting defects, surgical intervention may not be necessary until a pressure gradient of 40 mmHg is reached (5). One study reported that a 71-year-old patient with DCRV refused surgery and was kept on beta-blockers only (16). However, DCRV is typically progressive, resulting in increasing pressure gradients and right ventricular functional impairment if not treated in a timely manner (3,10). Therefore, surgery may be required in some patients later in the clinical course of the disease.

Few studies have reported DCRV in dogs, and its epidemiology in the aforementioned population has not been fully elucidated. To our knowledge, this study is the first to report a very old Standard Poodle dog with DCRV that was managed with conservative medical therapy for over a year.

DCRV is a rare congenital disease in dogs. When an old dog presents with clinical signs of heart disease, especially of the right-sided heart, DCRV should be considered because there are some differences between DCRV and pulmonic stenosis. Although surgery is the best treatment option for DCRV, supportive medical therapy could be the second best option depending on the severity of the pressure gradient across the obstruction, as in this case.

This study was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science (No. NRF-2020R1C1C1007282).

  1. Boon JA. Stenotic lesions. In: Boon JA, editor. Veterinary echocardiography. 2nd ed. New Jersey: Wiley-Blackwell. 2011: 504-507.
  2. Brambilla PG, Polli M, Pradelli D, Papa M, Rizzi R, Bagardi M, et al. Epidemiological study of congenital heart diseases in dogs: prevalence, popularity, and volatility throughout twenty years of clinical practice. PLoS One 2020; 15: e0230160.
    Pubmed KoreaMed CrossRef
  3. Fukushima R, Tanaka R, Suzuki S, Hamabe R, Machida N, Nakao S, et al. Epidemiological and morphological studies of double-chambered right ventricle in dogs. J Vet Med Sci 2011; 73: 1287-1293.
    Pubmed CrossRef
  4. Galiuto L, O’Leary PW, Seward JB. Double-chambered right ventricle: echocardiographic features. J Am Soc Echocardiogr 1996; 9: 300-305.
    Pubmed CrossRef
  5. Hoffman P, Wójcik AW, Rózański J, Siudalska H, Jakubowska E, Włodarska EK, et al. The role of echocardiography in diagnosing double chambered right ventricle in adults. Heart 2004; 90: 789-793.
    Pubmed KoreaMed CrossRef
  6. Kim JW, Yoon BG, Park JS, Kim JK, Lee KH, Park HJ, et al. Balloon dilation of double chambered right ventricle in a dog. Korean J Vet Serv 2017; 40: 67-70.
  7. Koffas H, Fuentes VL, Boswood A, Connolly DJ, Brockman DJ, Bonagura JD, et al. Double chambered right ventricle in 9 cats. J Vet Intern Med 2007; 21: 76-80.
    Pubmed CrossRef
  8. Koie H, Kurotobi EN, Sakai T. Double-chambered right ventricle in a dog. J Vet Med Sci 2000; 62: 651-653.
    Pubmed CrossRef
  9. Loukas M, Housman B, Blaak C, Kralovic S, Tubbs RS, Anderson RH. Double-chambered right ventricle: a review. Cardiovasc Pathol 2013; 22: 417-423.
    Pubmed CrossRef
  10. Martin JM, Orton EC, Boon JA, Mama KR, Gaynor JS, Bright JM. Surgical correction of double-chambered right ventricle in dogs. J Am Vet Med Assoc 2002; 220: 770-774, 768.
    Pubmed CrossRef
  11. Minors SL, O’Grady MR, Williams RM, O’Sullivan ML. Clinical and echocardiographic features of primary infundibular stenosis with intact ventricular septum in dogs. J Vet Intern Med 2006; 20: 1344-1350.
    Pubmed CrossRef
  12. Oliveira P, Domenech O, Silva J, Vannini S, Bussadori R, Bussadori C. Retrospective review of congenital heart disease in 976 dogs. J Vet Intern Med 2011; 25: 477-483.
    Pubmed CrossRef
  13. Park JG, Ryu HJ, Jung YS, Kim KJ, Lee BR, Jung BC, et al. Isolated double-chambered right ventricle in a young adult. Korean Circ J 2011; 41: 272-275.
    Pubmed KoreaMed CrossRef
  14. Sambugaro B, De Gennaro C, Vettorato E. Anaesthetic management and complications during cutting balloon and high-pressure balloon dilation in a dog with a double-chambered right ventricle. Vet Rec Case Rep 2022; 10: e264.
    CrossRef
  15. Schober KE, Rhinehart J, Kohnken R, Bonagura JD. Cutting balloon and high-pressure balloon dilation for palliative treatment of congenital double-chambered right ventricle and primary infundibular stenosis in a Golden retriever dog. J Vet Cardiol 2017; 19: 538-546.
    Pubmed CrossRef
  16. Tamai N, Ito S, Morimoto K, Inomata M, Yoshida T, Suzuki S, et al. Double chambered right ventricle with severe calcification of the tricuspid valve in an elderly woman: a case report. J Med Case Rep 2011; 5: 210.
    Pubmed KoreaMed CrossRef
  17. Visser LC, Scansen BA, Schober KE, Bonagura JD. Echocardiographic assessment of right ventricular systolic function in conscious healthy dogs: repeatability and reference intervals. J Vet Cardiol 2015; 17: 83-96.
    Pubmed CrossRef
  18. Ware WA, Bonagura JD, Scansen BA. Congenital valvular malformations. In: Ware WA, Bonagura JD, editors. Cardiovascular disease in companion animals: dog, cat and horse. 2nd ed. Boca Raton: CRC press. 2021: 490-500.
    CrossRef
  19. Willard MD, Eyster GE. Double-chambered right ventricle in two dogs. J Am Vet Med Assoc 1981; 178: 486-488.
  20. Winter RL, Clark WA, Kochie SL, Rhinehart JD. Long-term relief of obstruction in a dog with double-chambered right ventricle using combined cutting balloon and high-pressure balloon dilation. J Vet Cardiol 2021; 36: 180-185.
    Pubmed CrossRef

Article

Case Report

J Vet Clin 2023; 40(2): 130-134

Published online April 30, 2023 https://doi.org/10.17555/jvc.2023.40.2.130

Copyright © The Korean Society of Veterinary Clinics.

Double-Chambered Right Ventricle in an Old Standard Poodle Dog

Yunho Jeong1 , Yoonhwan Kim1 , Eunchan Lee2 , Ju-Hyun An3 , Sooyoung Choi2 , Jin-Young Chung1 , Jin-Ok Ahn1,*

1Department of Veterinary Internal Medicine and Institute of Veterinary Science, College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea
2Department of Veterinary Diagnostic Imaging, College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea
3Department of Emergency and Critical Care Medicine, College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea

Correspondence to:*joahn@kangwon.ac.kr

Received: February 3, 2023; Revised: March 20, 2023; Accepted: April 11, 2023

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A 12-year-old Standard Poodle presented with intermittent weakness and occasional dyspnea at the Veterinary Medicine Teaching Hospital of Kangwon National University. A grade of 4 out of 6 systolic murmur with an irregular tachycardic rhythm was auscultated on both sides of the chest. Systolic blood pressure was 140 mmHg. Panting was noticed in the hospital, but there was no crackle sound. Blood analysis revealed mild increases in liver panel levels (alanine aminotransferase 149 [reference interval, 19-70] U/L; and alkaline phosphatase, 185 [reference interval, 15-127] U/L) and severe increases in cardiac biomarker levels (n-terminal pro-brain natriuretic peptide, 4169 [reference interval, 50-900] pmol/L; and cardiac troponin I, 0.22 [reference interval, 0.03-0.12] ng/mL). On electrocardiography, irregularly irregular supraventricular tachycardic rhythm with an f-wave and no distinct p-wave was observed. Generalized cardiomegaly with an enlarged right atrium and left ventricle was confirmed on thoracic radiography. Moreover, hepatomegaly and an enlarged caudal vena cava were observed. Echocardiographic evaluation revealed a fibromuscular diaphragm in the right ventricle. Because of the obstructive lesion in the right ventricle, the right atrium and ventricle were enlarged (right atrial area index, 38.82 cm2/m2 [reference interval, 4.2-10.2 cm2/m2]; right ventricle end-diastolic area index, 14.152 cm2/m2 [reference interval, 4.9-10.92 cm2/m2]). Accordingly, the patient was diagnosed with double- chambered right ventricle (DCRV). Pimobendan, furosemide, enalapril, diltiazem, and S-adenosylmethionine (SAMe) were prescribed, and all symptoms were relieved. DCRV is a right-sided congenital heart defect resembling pulmonic valve stenosis. If symptoms are not severe, medical therapy can be facilitated without surgery or the balloon dilation.

Keywords: double-chambered right ventricle, congenital heart disease, pulmonary stenosis, right-sided heart failure, standard poodle dog

Introduction

Double-chambered right ventricle (DCRV) is an uncommon congenital heart disease in humans and dogs (9,12). Anomalous muscle bands or endogenous trabecular hypertrophy may cause abnormal separation (9). Two chambers exist: an inflow chamber with high pressure, and an outflow chamber with low pressure (8-11). In humans, DCRV is characterized by pressure gradients of over 20 mmHg between the two chambers and is frequently associated with other anomalies, including Ebstein’s anomaly, membranous ventricular septal defect, and double-outlet right ventricle (9). However, such association has not been identified in dogs.

The obstruction creates variable sized orifices for the two chambers (1). This pressure overload creates the same pathophysiologic changes within the heart as pulmonic valvular stenosis (1,3,10,18). Also, the high pressure chamber can lead to tricuspid insufficiency without any structural tricuspid valvular disease (1). Using echocardiography to diagnose this anomaly by confirming the anomalous muscle bands or turbulent flow within the right ventricle (1). We herein present a case of DCRV in an old, Standard Poodle dog having low pressure gradient between two chambers.

Case Report

A 12-year-old, 30-kg, intact male Standard Poodle was presented to the Veterinary Medicine Teaching Hospital of Kangwon National University for intermittent weakness, dyspnea under stressful situations, and nocturnal cough. He had no other previous illnesses except for otitis externa.

On physical examination, the dog had a slightly increased heart rate, varying from 160 to 220 bpm, with an irregular rhythm. A grade IV/VI systolic murmur was auscultated on both chest walls. Femoral pulse quality was normal, but pulse deficits were present. Systolic blood pressure was 130 mmHg. The capillary refill time was normal (<2 s), with a pink mucous membrane color. No remarkable lung sounds were noted. Blood analysis revealed mild elevations in liver panel levels (alanine aminotransferase, 149.77 U/L [reference interval, 19-70] U/L; and alkaline phosphatase, 185 [reference interval, 15-127]) and significant elevations in cardiac biochemical marker levels (cardiac troponin I, 0.22 ng/mL [reference interval, 0.03-0.12]; and N-terminal pro-brain natriuretic peptide 4169.5 pmol/L [reference interval, 0-900], vCheck canine NT-proBNP [V200 Analyzer, Bionote, Korea]). Since there was an irregularity in cardiac rhythm, electrocardiography was performed. Irregularly irregular tachyarrhythmia without significant p-waves was confirmed, and f-waves were present. The QRS complex was narrow (<0.07 s) and had a normal morphology. Based on this irregularity with f-waves, atrial fibrillation was diagnosed (Fig. 1). Thoracic and abdominal radiography revealed marked generalized cardiomegaly (vertebral heart score, 12.6 v) (Fig. 2A, B) and mild hepatomegaly (liver length: T11 vertebral length ratio, 7.71) (Fig. 2C). Two-dimensional echocardiographic examination revealed a severely enlarged right ventricle and atrium (Fig. 3A). A thin membrane dividing the right ventricle before the right ventricular outflow tract was observed (Fig. 3B). The proximal chamber ventricular free wall showed focal concentric hypertrophy with eccentric changes in the rest of the ventricular wall (Fig. 3C). Moreover, there was turbulent flow along the obstruction area (Fig. 3D). However, it was not possible to measure flow velocity across the obstructed area. The estimated pressure gradient between the two chambers was 18 mmHg. Severe tricuspid regurgitation with a velocity of 2.75 m/s due to right chamber dilation was confirmed by color and continuous-wave Doppler echocardiography (Fig. 3E, F). Pulmonic valve degeneration or regurgitation was not observed. Right ventricular systolic function decreased (fractional area change [FAC], 28.6% [reference interval, 33.9-56.3%]) (17). There was no other evidence of pulmonary hypertension other than tricuspid regurgitation.

Figure 1. Electrocardiography (ECG) results of the patient. ECG reveals irregularly irregular rhythm without noticeable p-waves. F-waves can also be identified. Accordingly, atrial fibrillation can be diagnosed.

Figure 2. Radiographs from the dog with double-chambered right ventricle (DCRV). Generalized cardiomegaly (vertebral heart score, 12.6 v = 6.4 [L] + 6.2 [S]) with increased sternal contact can be observed in thoracic radiographs (A, B). Abdominal radiograph shows hepatomegaly (liver length: T11 vertebral length ratio, 7.71) (C).

Figure 3. Echocardiographic findings. A severely enlarged right heart can be observed on the right parasternal long axis 4-chamber view (A). A thin fibromuscular structure dividing the right ventricle can be observed (white arrow) in the right parasternal short axis view (B). There is focal muscle hypertrophy before the obstructive lesion in the right parasternal short axis view. Wall thickness is 20.8 mm (C). Color Doppler echocardiography revealed turbulent flow along the obstructive area in the mid-right ventricle. Unfortunately, we were unable to evaluate flow velocity across the fibromuscular region, though estimated pressure gradient was 18 mmHg (D). Color Doppler echocardiography at the right parasternal long-axis 4 chamber view shows severe tricuspid regurgitation due to inadequate coaptation of tricuspid leaflets (E). The regurgitant flow velocity is 2.75 m/s, and the peak pressure gradient is 30.3 mmHg on continuous wave Doppler echocardiography at the left apical 4 chamber view (F). AO, aorta; LA, left atrium; LV, left ventricle; MPA, main pulmonary artery; PV, pulmonic valve; RA, right atrium; RV, right ventricle; RVO, right ventricular outflow.

Accordingly, the patient was diagnosed with DCRV, right-sided congestive heart failure, and atrial fibrillation. To control the symptoms and mild hepatomegaly, 1 mg/kg (PO q 12 h) of furosemide (Lasix; HANDOK, Seoul, Korea), 0.25 mg/kg (PO q 12 h) of pimobendan (Vetmedin; Boehringer Ingelheim, Ingelheim am Rhein, Germany), 0.5 mg/kg (PO q 12 h) of enalapril (Enalapril Maleate; CMG pharmaceutical, Seoul, Korea), 0.5 mg/kg (PO q 12 h) of diltiazem (Herben; HKinno.N, Cheongju, Korea), 0.5 mg/kg (PO q 12 h) of omeprazole (Omed; SK chemicals, Seongnam, Korea), and SAMe (S-adenosylmethionine; Zentonil; Vetoquinol, Lure, France) were prescribed.

After treatment, according to the owner, the dog experienced no further weakness or dyspnea. A physical examination performed again revealed an irregular heart rate of 140-160 bpm. Atrial fibrillation was still present on electrocardiography; however, the average heart rate in the hospital was 130 bpm. Radiographic evaluation showed slightly decreased cardiac size (Fig. 4A) and reduced hepatomegaly (vertebral heart score, 11.8 v; and liver length: T11 vertebral length ratio, 6.82) (Fig. 4B). Echocardiography confirmed elevated right ventricular systolic function (FAC, 44.2%). Overall, the results were good and the same medications were prescribed.

Figure 4. Radiographs after 3 months of medical therapy. Generalized cardiomegaly is slightly decreased in the thoracic radiograph (vertebral heart score, 11.8 v = 5.6 v [L] + 6.2 v [S]) (A). Abdominal radiograph shows reduced hepatomegaly (liver length: T11 vertebral length ratio, 6.8) (B).

Discussion

DCRV is one of the most uncommon congenital heart diseases in dogs, with a known prevalence of 1%-1.8% among dogs with congenital heart disease (2,12). The two main classifications of this congenital anomaly can be made according to the differences in the structure that divides the right ventricle (13). Type 1 is caused by anomalous muscle bands, whereas type 2 is caused by trabecular hypertrophy (13). Moreover, the obstructive lesion is described as “high” when it is close to the pulmonary valve and “low” when it is close to the apex (4,5). There have been some discussions regarding the terminology used to name this anomaly. Primary infundibular stenosis, mid-ventricular stenosis, and DCRV are the nomenclatures used (1). These can be distinguished based on the location and characteristics of the obstruction. The cardiac remodeling and hemodynamics of DCRV are influenced by pressure overload in the right ventricle, resulting in severe right-sided congestive heart failure, eventually like pulmonary stenosis (3,10,18). However, some differences exist between these congenital diseases, including breed prevalence and treatment implications. DCRV is usually associated with other malformations (2,9,12); however, in this case, only isolated DCRV was observed.

Treatment options to control this mid-ventricular obstruction include surgical resection, catheter-based procedures, and conservative medical therapy (10,18,20). Of these modalities, surgery is the most successful (10,15,18,19). However, availability and affordability are major obstacles for this approach (10,15). Balloon dilation of the obstruction has been tried in several cases (6,10,14,15,20), though not all cases showed the best results. Some patients have favorable long-term results (6,20). The medical management of DCRV is almost the same as that of pulmonic stenosis (9,18). To minimize cardiac workload and excessive oxygen consumption, beta-blockers are commonly prescribed when there is no evidence of congestion.

Few studies have reported DCRV in dogs, most of whom die at a young age (3,12). Symptoms are progressive, resulting exercise intolerance, cough, cyanosis, panting, syncope, and sudden death in humans, dogs, and cats (3,7). However, if patients undergo surgery or balloon dilation, the prognosis is good (10,20). In this case, the patient was diagnosed at 12 years of age without significant congestive signs. The pressure gradient across the ostium was believed to be 18 mmHg, which is much less than that in other cases (3,6,10,20). In humans, when a patient does not present with significant coexisting defects, surgical intervention may not be necessary until a pressure gradient of 40 mmHg is reached (5). One study reported that a 71-year-old patient with DCRV refused surgery and was kept on beta-blockers only (16). However, DCRV is typically progressive, resulting in increasing pressure gradients and right ventricular functional impairment if not treated in a timely manner (3,10). Therefore, surgery may be required in some patients later in the clinical course of the disease.

Few studies have reported DCRV in dogs, and its epidemiology in the aforementioned population has not been fully elucidated. To our knowledge, this study is the first to report a very old Standard Poodle dog with DCRV that was managed with conservative medical therapy for over a year.

Conclusions

DCRV is a rare congenital disease in dogs. When an old dog presents with clinical signs of heart disease, especially of the right-sided heart, DCRV should be considered because there are some differences between DCRV and pulmonic stenosis. Although surgery is the best treatment option for DCRV, supportive medical therapy could be the second best option depending on the severity of the pressure gradient across the obstruction, as in this case.

Acknowledgements

This study was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science (No. NRF-2020R1C1C1007282).

Conflicts of Interest

The authors have no conflicting interests.

Fig 1.

Figure 1.Electrocardiography (ECG) results of the patient. ECG reveals irregularly irregular rhythm without noticeable p-waves. F-waves can also be identified. Accordingly, atrial fibrillation can be diagnosed.
Journal of Veterinary Clinics 2023; 40: 130-134https://doi.org/10.17555/jvc.2023.40.2.130

Fig 2.

Figure 2.Radiographs from the dog with double-chambered right ventricle (DCRV). Generalized cardiomegaly (vertebral heart score, 12.6 v = 6.4 [L] + 6.2 [S]) with increased sternal contact can be observed in thoracic radiographs (A, B). Abdominal radiograph shows hepatomegaly (liver length: T11 vertebral length ratio, 7.71) (C).
Journal of Veterinary Clinics 2023; 40: 130-134https://doi.org/10.17555/jvc.2023.40.2.130

Fig 3.

Figure 3.Echocardiographic findings. A severely enlarged right heart can be observed on the right parasternal long axis 4-chamber view (A). A thin fibromuscular structure dividing the right ventricle can be observed (white arrow) in the right parasternal short axis view (B). There is focal muscle hypertrophy before the obstructive lesion in the right parasternal short axis view. Wall thickness is 20.8 mm (C). Color Doppler echocardiography revealed turbulent flow along the obstructive area in the mid-right ventricle. Unfortunately, we were unable to evaluate flow velocity across the fibromuscular region, though estimated pressure gradient was 18 mmHg (D). Color Doppler echocardiography at the right parasternal long-axis 4 chamber view shows severe tricuspid regurgitation due to inadequate coaptation of tricuspid leaflets (E). The regurgitant flow velocity is 2.75 m/s, and the peak pressure gradient is 30.3 mmHg on continuous wave Doppler echocardiography at the left apical 4 chamber view (F). AO, aorta; LA, left atrium; LV, left ventricle; MPA, main pulmonary artery; PV, pulmonic valve; RA, right atrium; RV, right ventricle; RVO, right ventricular outflow.
Journal of Veterinary Clinics 2023; 40: 130-134https://doi.org/10.17555/jvc.2023.40.2.130

Fig 4.

Figure 4.Radiographs after 3 months of medical therapy. Generalized cardiomegaly is slightly decreased in the thoracic radiograph (vertebral heart score, 11.8 v = 5.6 v [L] + 6.2 v [S]) (A). Abdominal radiograph shows reduced hepatomegaly (liver length: T11 vertebral length ratio, 6.8) (B).
Journal of Veterinary Clinics 2023; 40: 130-134https://doi.org/10.17555/jvc.2023.40.2.130

References

  1. Boon JA. Stenotic lesions. In: Boon JA, editor. Veterinary echocardiography. 2nd ed. New Jersey: Wiley-Blackwell. 2011: 504-507.
  2. Brambilla PG, Polli M, Pradelli D, Papa M, Rizzi R, Bagardi M, et al. Epidemiological study of congenital heart diseases in dogs: prevalence, popularity, and volatility throughout twenty years of clinical practice. PLoS One 2020; 15: e0230160.
    Pubmed KoreaMed CrossRef
  3. Fukushima R, Tanaka R, Suzuki S, Hamabe R, Machida N, Nakao S, et al. Epidemiological and morphological studies of double-chambered right ventricle in dogs. J Vet Med Sci 2011; 73: 1287-1293.
    Pubmed CrossRef
  4. Galiuto L, O’Leary PW, Seward JB. Double-chambered right ventricle: echocardiographic features. J Am Soc Echocardiogr 1996; 9: 300-305.
    Pubmed CrossRef
  5. Hoffman P, Wójcik AW, Rózański J, Siudalska H, Jakubowska E, Włodarska EK, et al. The role of echocardiography in diagnosing double chambered right ventricle in adults. Heart 2004; 90: 789-793.
    Pubmed KoreaMed CrossRef
  6. Kim JW, Yoon BG, Park JS, Kim JK, Lee KH, Park HJ, et al. Balloon dilation of double chambered right ventricle in a dog. Korean J Vet Serv 2017; 40: 67-70.
  7. Koffas H, Fuentes VL, Boswood A, Connolly DJ, Brockman DJ, Bonagura JD, et al. Double chambered right ventricle in 9 cats. J Vet Intern Med 2007; 21: 76-80.
    Pubmed CrossRef
  8. Koie H, Kurotobi EN, Sakai T. Double-chambered right ventricle in a dog. J Vet Med Sci 2000; 62: 651-653.
    Pubmed CrossRef
  9. Loukas M, Housman B, Blaak C, Kralovic S, Tubbs RS, Anderson RH. Double-chambered right ventricle: a review. Cardiovasc Pathol 2013; 22: 417-423.
    Pubmed CrossRef
  10. Martin JM, Orton EC, Boon JA, Mama KR, Gaynor JS, Bright JM. Surgical correction of double-chambered right ventricle in dogs. J Am Vet Med Assoc 2002; 220: 770-774, 768.
    Pubmed CrossRef
  11. Minors SL, O’Grady MR, Williams RM, O’Sullivan ML. Clinical and echocardiographic features of primary infundibular stenosis with intact ventricular septum in dogs. J Vet Intern Med 2006; 20: 1344-1350.
    Pubmed CrossRef
  12. Oliveira P, Domenech O, Silva J, Vannini S, Bussadori R, Bussadori C. Retrospective review of congenital heart disease in 976 dogs. J Vet Intern Med 2011; 25: 477-483.
    Pubmed CrossRef
  13. Park JG, Ryu HJ, Jung YS, Kim KJ, Lee BR, Jung BC, et al. Isolated double-chambered right ventricle in a young adult. Korean Circ J 2011; 41: 272-275.
    Pubmed KoreaMed CrossRef
  14. Sambugaro B, De Gennaro C, Vettorato E. Anaesthetic management and complications during cutting balloon and high-pressure balloon dilation in a dog with a double-chambered right ventricle. Vet Rec Case Rep 2022; 10: e264.
    CrossRef
  15. Schober KE, Rhinehart J, Kohnken R, Bonagura JD. Cutting balloon and high-pressure balloon dilation for palliative treatment of congenital double-chambered right ventricle and primary infundibular stenosis in a Golden retriever dog. J Vet Cardiol 2017; 19: 538-546.
    Pubmed CrossRef
  16. Tamai N, Ito S, Morimoto K, Inomata M, Yoshida T, Suzuki S, et al. Double chambered right ventricle with severe calcification of the tricuspid valve in an elderly woman: a case report. J Med Case Rep 2011; 5: 210.
    Pubmed KoreaMed CrossRef
  17. Visser LC, Scansen BA, Schober KE, Bonagura JD. Echocardiographic assessment of right ventricular systolic function in conscious healthy dogs: repeatability and reference intervals. J Vet Cardiol 2015; 17: 83-96.
    Pubmed CrossRef
  18. Ware WA, Bonagura JD, Scansen BA. Congenital valvular malformations. In: Ware WA, Bonagura JD, editors. Cardiovascular disease in companion animals: dog, cat and horse. 2nd ed. Boca Raton: CRC press. 2021: 490-500.
    CrossRef
  19. Willard MD, Eyster GE. Double-chambered right ventricle in two dogs. J Am Vet Med Assoc 1981; 178: 486-488.
  20. Winter RL, Clark WA, Kochie SL, Rhinehart JD. Long-term relief of obstruction in a dog with double-chambered right ventricle using combined cutting balloon and high-pressure balloon dilation. J Vet Cardiol 2021; 36: 180-185.
    Pubmed CrossRef

Vol.41 No.1 February 2024

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The Korean Society of Veterinary Clinics

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