An Armored Heart: A Diagnosis Hidden in Plain Sight.

We report a case of an overtly symptomatic patient with delayed diagnosis of massive (>25-mm thickness), circular, constrictive pericarditis. Our patient underwent a successful surgical pericardiectomy-a high-risk procedure-revealing an armored heart, with an impressive clinical improvement. Diagnosis of constrictive pericarditis is challenging and requires high clinical suspicion.

A failing right heart in an eggshell: A case report of idiopathic constrictive pericarditis.

key Clinical Message: Constrictive Pericarditis is a rare fibrotic conversion of the pericardium that results in non-specific clinical symptoms such as hepatomegaly, ascites, pleural effusions, and lower extremity edema. A multi-modal diagnostic approach with cardiac imaging tools, cardiac hemodynamic measurements, and tissue biopsy can be used to diagnose Constrictive Pericarditis. Abstract: Constrictive Pericarditis is a rare complication resulting in the fibrotic conversion of the pericardium secondary to idiopathic, infective, post-surgical, or post-radiation etiologies. The rigid and restrictive nature of the pericardium can result in non-specific symptoms of volume overload that can mimic liver cirrhosis or congestive heart failure. We present the case of a 73-year-old female with constrictive pericarditis who presented with vague symptoms of abdominal pain, abdominal bloating, and bilateral lower extremity edema. This case report highlights the clinical manifestation, invasive, and non-invasive diagnostic work-up, and management of constrictive pericarditis.

Constrictive pericarditis in a patient with fiberglass lung disease: a case report.

BACKGROUND: Fiberglass has a larger aerodynamic diameter and is less likely to be inhaled into the lungs. Further, it will be cleared even if it is mechanically broken into smaller pieces and inhaled into the lungs. Fiberglass lung disease has been well documented if long term exposure but was thought reversible and would not cause severe diseases. The diagnosis of fiberglass lung disease depends on exposure history and histopathological findings. However, the exact occupational exposure history is often difficult to identify because mixed substance exposure often occurs and fiberglass disease is not as well-known as asbestosis. CASE PRESENTATION: A 66-year-old man had unexplained transudative pericardial effusion requiring pleural pericardial window operation twice at another medical center where asbestosis was told because of his self-reported long-term asbestosis exposure and the histopathological finding of a ferruginous body in his lung. Constrictive pericarditis developed two years later and resulted in congestive heart failure. Radical pericardiectomy combined with lung biopsy was performed following chest computed tomography imaging and the transudative nature of pericardial effusion not compatible with asbestosis. However, the histopathologic findings of his lung and pericardium at our hospital only showed chronic fibrosis without any asbestosis body. The patient's lung was found to be extremely fragile during a lung biopsy; histopathologic specimens were reviewed, and various fragments of fiberglass were found in the lung and pericardium. The patient's occupational exposure was carefully reevaluated, and he restated that he was only exposed to asbestosis for 1-2 years but was heavily exposed to fiberglass for more than 40 years. This misleading exposure history was mainly because he was only familiar with the dangers of asbestos. Since most fiberglass lung diseases are reversible and the symptoms of heart failure resolve soon after surgery, only observation was needed. Ten months after radical pericardiectomy, his symptoms, pleural effusion, and impaired pulmonary function eventually resolved. CONCLUSION: Fiberglass could cause inflammation of the pericardium, resulting in pericardial effusion and constrictive pericarditis, which could be severe and require radical pericardiectomy. Exact exposure history and histopathological examinations are the key to diagnosis.

Pericardial Diseases: International Position Statement on New Concepts and Advances in Multimodality Cardiac Imaging.

Pericardial diseases have gained renewed clinical interest, leading to a renaissance in the field. There have been many recent advances in pericardial diseases in both multimodality cardiac imaging of diagnoses, such as recurrent, transient constrictive and effusive-constrictive pericarditis, and targeted therapeutics, especially anti-interleukin (IL)-1 agents that affect the inflammasome as part of autoinflammatory pathophysiology. There remains a large educational gap for clinicians, leading to variability in evaluation and management of these patients. The latest pericardial imaging (American Society of Echocardiography, European Association of Cardiovascular Imaging) and clinical guidelines (European Society of Cardiology) are >8-10 years of age and may not reflect current practice. Recent clinical trials involving anti-IL-1 agents in recurrent pericarditis, including anakinra (AIRTRIP), rilonacept (RHAPSODY), and goflikicept have demonstrated their efficacy. The present document represents an international position statement from world leaders in the pericardial field, focusing on novel concepts and emphasizing the role of multimodality cardiac imaging as well as new therapeutics in pericardial diseases.

The "Old yet New" Echocardiographic Finding for Constrictive Pericarditis Following Purulent Pericarditis: A Case Report.

Purulent pericarditis (PP) is a localized infection of the pericardial cavity with suppuration that can be life-threatening. Treatment for PP consists of pericardial drainage and antimicrobial therapy. Constrictive pericarditis (CP), a form of diastolic heart failure that arises because an inelastic thickened pericardium, is a possible related dreadful complication of PP. Several echocardiographic findings suggestive of CP have been reported, but some require measurements or are difficult to reproduce. This case report presents a simple echocardiographic finding that reflects the clinical course of transient CP (TCP). A 76-year-old Japanese man presented to our hospital with chest pain and dyspnea. He was diagnosed with PP caused by Streptococcus pyogenes and treated with pericardial drainage and benzylpenicillin. The response to the treatment of the infection was favorable, but subsequent echocardiography and cardiac catheterization revealed a CP complication. Treatment with colchicine and ibuprofen was initiated, with improvement in CP within three months. During CP, a restricted right ventricular (RV) motion and movement of the liver towards the heart were observed before other echocardiographic findings suggestive of CP. Furthermore, this echocardiographic finding disappeared and normalized as CP improved. In this case of TCP following PP, changes in the echocardiographic "RV sliding" sensitively reflected the clinical course of CP. This simple finding may indicate inflammation of the pericardium and could be useful for the diagnosis and follow-up of CP.

Impact of pericardial calcification on early postoperative outcomes after pericardiectomy: a retrospective observational study.

BACKGROUND: Owing to the lack of understanding of the clinical significance of pericardial calcification during pericardiectomy, whether pericardial calcification should be considered when determining the optimal timing for pericardiectomy is debatable. We aimed to investigate the effect of pericardial calcification on early postoperative outcomes in patients who underwent pericardiectomy for constrictive pericarditis. METHODS: Altogether, 44 patients who underwent pericardiectomy for constrictive pericarditis were enrolled. After excluding three patients who underwent concurrent surgeries, a total of 41 patients were categorized into two groups based on the presence of pericardial calcification as determined by preoperative computed tomography and pathological examination. Preoperative clinical and imaging characteristics, intraoperative data, and early postoperative outcomes were compared between the two groups. A multivariable analysis was performed to identify the factors associated with postoperative complications. RESULTS: The group with and without PC comprised 21 and 20 patients, respectively. No significant differences were observed in 30-day mortality (n = 1 [5%]) in the group with pericardial calcification and no mortality in the group without pericardial calcification (p > 0.999). Other early postoperative outcome variables did not demonstrate any significant differences between the two groups. However, the use of cardiopulmonary bypass was associated with postoperative complications (p < 0.009, odds ratio: 63.5, 95% confidence interval: 5.13-3400). CONCLUSIONS: Pericardial calcification did not significantly affect the postoperative outcomes after pericardiectomy. Further comprehensive studies, including those with larger sample sizes and longitudinal designs, are necessary to determine whether pericardial calcification can significantly influence the timing of surgical intervention.

Purulent Streptococcus intermedius Pericarditis in the Setting of Histoplasma Mediastinal Lymphadenitis: A Case Report and Literature Review.

Purulent pericarditis is a rare and potentially life-threatening condition characterized by infection of the pericardial space. We describe a case of purulent bacterial pericarditis in a 41-year-old male with no significant medical or surgical history who had concomitant pulmonary Histoplasma infection. Streptococcus intermedius was the bacteria directly responsible for the pericardial infection, though co-infection with histoplasmosis likely predisposed him to develop purulent pericarditis. We hypothesize histoplasmosis caused mediastinal lymphadenopathy, facilitating contact between a necrotic lymph node and the pericardium and contiguous suppuration of bacteria to the pericardial space. We treated S. intermedius and Histoplasma capsulatum with ceftriaxone and amphotericin B, respectively. Additionally, the patient presented in cardiac tamponade requiring emergent pericardiocentesis and drain placement. His course was also complicated by pericardial constriction. Cardiac magnetic resonance confirmed this, showing inflamed pericardium and abnormal septal motion with inspiration, and he had symptoms refractory to antimicrobials and anti-inflammatories. As such, he required pericardiectomy. This case demonstrates maintaining suspicion for secondary infectious foci as a contributor to the pathogenesis of purulent pericarditis is important, as pulmonary histoplasmosis played a pivotal role in allowing S. intermedius to spread to the pericardium but was not the primary infection. It also highlights the multifaceted evaluation and management of purulent pericarditis, highlighting the role of echocardiography and emergent pericardial drainage if cardiac tamponade is present, the importance of targeted antimicrobial therapy, the superior ability of cardiac magnetic resonance to identify pericardial constriction as a sequela of purulent pericarditis, and indications for pericardiectomy.

Rosai-Dorfman Disease as Constrictive Pericarditis: An Unusual Childhood Presentation.

Rosai-Dorfman disease (RDD) is a rare, multisystemic, histiocytic disorder that usually presents with painless cervical lymphadenopathy. We describe a case of constrictive effusive pericarditis with congestive cardiac failure in a six-year-old child as an initial presentation of RDD. The child underwent pericardiectomy and was treated with steroids, following which the symptoms resolved entirely. While tuberculosis accounts for the majority of cases presenting with constrictive pericarditis in developing countries, the presentation of RDD can be easily missed if not kept in mind as a possibility. This case report documents the unique presentation of a rare disease.

COVID-related constrictive pericarditis requiring pericardiectomy: a case report.

BACKGROUND: The COVID-19 pandemic was primarily considered a respiratory malady in the early phases of the outbreak. However, as more patients suffer from this illness, a myriad of symptoms emerge in organ systems separate from the lungs. Among those patients with cardiac involvement, myocarditis, pericarditis, myocardial infarction, and arrhythmia were among the most common manifestations. Pericarditis with pericardial effusion requiring medical or interventional treatments has been previously reported in the acute setting. Notably, chronic pericarditis with pericardial thickening resulting in constriction requiring sternotomy and pericardiectomy has not been published to date. CASE PRESENTATION: A patient with COVID-19-associated constrictive pericarditis three years after viral infection requiring pericardiectomy was reported. The COVID-19 infection originally manifested as anosmia and ageusia. Subsequently, the patient developed dyspnea, fatigue, right-sided chest pressure, bilateral leg edema, and abdominal fullness. Following recurrent right pleural effusions and a negative autoimmune work-up, the patient was referred for cardiothoracic surgery for pericardiectomy when radiographic imaging and hemodynamic assessment were consistent with constrictive pericarditis. Upon median sternotomy, the patient's pericardium was measured to be 8 mm thick. Descriptions of the clinical, diagnostic, and therapeutic features are provided. Within the first week after the operation, the patient's dyspnea resolved; one month later, leg edema and abdominal bloating were relieved. CONCLUSIONS: Although an association between COVID-19 and cardiac complications has been established, this case adds another element of virus severity and chronic manifestations. The need for sternotomy and pericardiectomy to treat COVID-19-related constrictive pericarditis is believed to be the first reported diagnosis.

Pericardial Calcification: An Uncommon Case with Intraventricular Extension.

An 80-year-old man presented to the cardiology outpatient clinic due to shortness of breath. His past medical history included alcohol intake, hypertension, inferior wall myocardial infarction (five years ago), an ischemic stroke, and permanent atrial fibrillation (diagnosed three years before the current examination). A physical exam revealed a decreased intensity of S1 and S2, irregular rate and rhythm, and no murmurs nor friction rub. X-rays, Computed Tomography, and echocardiography exhibited pericardial calcification, involving mostly the inferior wall and protruding into the left ventricle. A diagnosis of constrictive pericarditis due to pericardial calcification was established and considered idiopathic. Even when it may be related to ischemic heart disease, post-infarction pericarditis could explain how the calcification extended to adjacent territory perfused by the circumflex coronary artery. Combined imaging studies were crucial not only for identifying calcium deposits in the pericardium but also in assessing a patient inherently prone to co-existing and exacerbating conditions. Even though pericardiectomy allows for removal of the clinical manifestations of congestive pericarditis in the most symptomatic patients with pericardial calcification, among patients like ours, with tolerable symptoms, cardiologists should discuss the therapeutic options considering the patient's choices, potentially including a rehabilitation plan as part of non-pharmacological management.

Pericardial Diseases and Best Practices for Pericardiectomy: JACC State-of-the-Art Review.

Remarkable advances have occurred in the understanding of the pathophysiology of pericardial diseases and the role of multimodality imaging in this field. Medical therapy and surgical options for pericardial diseases have also evolved substantially. Pericardiectomy is indicated for chronic or irreversible constrictive pericarditis, refractory recurrent pericarditis despite optimal medical therapy, or partial agenesis of the pericardium with a complication (eg, herniation). A multidisciplinary evaluation before pericardiectomy is essential for optimal patient outcomes. Overall, given the good outcomes reported, radical pericardiectomy on cardiopulmonary bypass, if feasible, is the preferred approach. Due to patient complexity, as well as the technical aspects of the surgery, pericardiectomy should be performed at high-volume centers that have the required expertise. The current review highlights the essential features of this multidisciplinary approach from diagnosis to recovery in patients undergoing pericardiectomy.

Rare severe constrictive pericarditis complication in Erdheim-Chester disease: A case report and literature review.

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis with diverse clinical features. It is characterized by systemic histiocyte infiltration of the bone, skin, central nervous system, lung, kidney, and cardiovascular system. Pericardial involvement is frequently revealed through either pericardial effusion or pericardial thickening in patients with ECD. Although most patients remain asymptomatic, progressive pericarditis, effusion, or cardiac tamponade may occur. Herein, we report a rare and unusual presentation of ECD in a 51-year-old man who experienced severe constrictive pericarditis. The patient presented with uncontrolled fluid retention and heart failure. After the diagnosis of ECD, interferon alpha treatment was administered. The patient recovered dramatically with decreased pleural and pericardial effusion, as well as improvements in the echocardiographic signs of constrictive pericarditis. Despite several therapeutic options described in the literature for managing ECD-related pericardial disease, a standard treatment has not been established. This report highlights the importance of early treatment based on accurate diagnosis of an unusual ECD complication.

Combinational elastography prior to pericardiectomy to assess liver condition in patients with constrictive pericarditis.

A 68-year-old man was diagnosed with pericarditis associated with immunoglobulin G4-related disease and was administered prednisolone 2 years prior to presentation. During the process of tapering off from prednisolone 1 year later, edema of the lower legs and pleural effusion worsened. He gradually developed dyspnea on exertion, and laboratory examinations revealed elevated liver enzyme levels. Diuretics were administered; however, the symptoms did not resolve. Transthoracic echocardiography and cardiac catheterization revealed findings consistent with those of constrictive pericarditis. Pericardiectomy was considered and the perioperative risks due to possible recovery from liver dysfunction were discussed. Combinational elastography was subsequently performed. The results indicated the absence of liver fibrosis, suggesting that liver dysfunction was attributable to liver congestion; thus, the liver dysfunction was considered reversible. Subsequently, pericardiectomy was performed. Given that constrictive pericarditis can lead to liver dysfunction due to congestion, the perioperative risk is often controversial when considering surgical interventions. Learning objective: Combinational elastography may be useful in the preoperative evaluation of patients with cardiac diseases complicated by liver dysfunction to distinguish liver fibrosis, understand the pathogenesis of liver dysfunction, and determine subsequent treatment strategies.

Perioperative management of constrictive pericarditis with cardiac cirrhosis: A case report.

INTRODUCTION: The interactions between the heart and liver have been known for a long time, pericarditis constrictive could cause congestive hepatopathy via right-sided heart failure. Liver cirrhosis correlates with a high risk of mortality so perioperative management greatly influences outcomes. CASE PRESENTATION: An Indonesian man, 50 years old, complained of breath shortness. The patient had a history of pulmonary tuberculosis and was declared cured 30 years ago. The patient began experiencing fatigue 14 years ago, and the patient was diagnosed with constrictive pericarditis 5 years ago. Currently, the patient has an increased jugular venous pressure of 9 cmH2O and abnormal laboratory indicators, including a platelet count of 121,000/µL, albumin count of 3.41 g/L, direct bilirubin count of 0.7 mg/dL, total bilirubin count of 1.4 mg/dL, and INR of 1.4. Echocardiography revealed left ventricle hypertrophy, diastolic dysfunction, and right ventricle failure. Cardiac CT scan showed pericardial calcification. Abdominal ultrasound showed liver congestive and splenomegaly. Transient elastography showed severe fibrosis in liver and stiffness in spleen. The patient underwent pericardiectomy with CTP score of 6 and MELD of 12. The surgery was successful, and the complaint was reduced. The patient experienced an improvement in his condition and able to carry out activities well after 2 years post-surgery. DISCUSSION: The patient has no contraindications to pericardiectomy, CTP class A (5-6) and MELD score <13.5 has a low risk of mortality. CONCLUSION: CTP and MELD scores predict life expectancy in post-surgery cardiac cirrhosis patients.

A Rare Case of Immunoglobulin G4-Related Constrictive Pericarditis Diagnosed Via Multimodality Imaging.

Constrictive pericarditis (CP) presents as a pathophysiological state where the pericardium becomes inelastic due to fibrotic changes, most commonly secondary to a protracted inflammatory process. The disease is characterized by compromised diastolic cardiac function due to loss of pericardial compliance. Immunoglobulin G4 (IgG4)-related disease, an entity marked by the insidious proliferation of IgG4-positive plasma cells and subsequent fibrosis within various organs, is an infrequent but recognized cause of CP. A case of a 55-year-old male patient with clinical manifestations of dyspnea and edema in the lower extremities elucidates the diagnostic complexity inherent to CP. Echocardiography revealed a constellation of signs, including annulus reversus, septal bounce, and a congested inferior vena cava; cardiac magnetic resonance imaging (MRI) demonstrated diffuse pericardial thickening with delayed gadolinium enhancement, suggestive of a long-term inflammatory state; and right heart catheterization confirmed the hemodynamic hallmark of CP-equalization of diastolic pressures across the cardiac chambers. The serological analysis elicited elevated serum levels of IgG4 and IgE, pointing to the differential diagnosis of IgG4-related disease. Given the nonspecific clinical presentation of IgG4-related CP, a heightened index of suspicion combined with a systematic approach to imaging and serological evaluation is paramount.

Clinicopathological features of immunoglobulin G4-related constrictive pericarditis.

AIM: Constrictive pericarditis (CP) is characterised by scarring fibrosis and a loss of pericardial elasticity, which causes heart failure. IgG4 (immunoglobulin G4)-related disease (IgG4-RD) is a systemic fibro-inflammatory disease characterised by the infiltration of IgG4-immunopositive plasmacytes and high serum IgG4 levels that frequently shape tumorous lesions. Although pericardial involvement of IgG4-RD is rare, with indications of CP, pericardial effusion and irregular masses, the clinical and pathological features remain unclear. In this study, we examined the relationship between CP and IgG4-RD. METHODS: Among 35 thick-walled CP cases (histologically pericardial thickening ≥2 mm), eight cases were aetiology identified. Using the diagnostic criteria for IgG4-RD, 11 cases were classified as IgG4-CP, whereas the remainder were considered true idiopathic CP (16 cases) and the clinical pathological features were evaluated. RESULTS: Compared with the other groups, the IgG4-CP group was more common in men and associated with low-grade fever and massive pericardial effusion with frequent recurrence. Deaths resulting from heart failure occurred in a few cases of the IgG4-CP group, but not in other groups. An increase in C-reactive protein and a high positivity rate of anti-nuclear antibodies frequently occurred in the IgG4-CP group. Histologically, the IgG4-CP group included lymphoid follicle, eosinophil infiltration and few calcifications. CONCLUSIONS: Pericardial IgG4-RD occurs not only as nodular lesions, but also as thick-walled CP, and accounts for approximately 40% of thick-walled CP cases of unknown cause. The predominant clinical characteristic was refractory and recurrent pericardial effusion. Recognising IgG4-RD as a cause of CP is important to initiate appropriate therapy.

The Important Role of Preoperative D-Dimer in Constrictive Pericarditis.

Background: The impact of coagulation indicators on postoperative outcomes of patients with constrictive pericarditis undergoing pericardiectomy has been poorly investigated. This study aimed to assess the prognostic role of preoperative coagulation indicators in these patients. Methods: We retrospectively included 158 patients with constrictive pericarditis undergoing pericardiectomy. The diagnostic values of coagulation indicators for postoperative complications were evaluated by ROC curves. Patients were divided into two groups according to the cutoff value calculated by ROC curve. Postoperative outcomes were compared between the two groups. Logistic regression analysis was performed to identify risk factors of postoperative complications. Results: ROC curve showed that among different coagulation indicators, preoperative D-dimer (DD) level could effectively identify patients with postoperative complications (AUC 0.771, 95% CI 0.696-0.847, P < 0.001). Patients were divided into the low DD group and the high DD group. The comparison of postoperative outcomes suggested that high preoperative DD level was significantly associated with longer durations of vasoactive agents using (P = 0.018), intubation (P = 0.020), ICU stay (P = 0.008), chest drainage (P=0.004) and hospital stay (P = 0.002). Multivariable analysis showed that high preoperative DD level was the independent risk factor of postoperative complications (OR 6.892, 95% CI 2.604-18.235, P < 0.001). Conclusion: High preoperative DD level was significantly linked to poor postoperative outcomes and could provide an effective prediction ability for postoperative complications in patients with constrictive pericarditis.

Outcomes and Risk Factors Associated with Pericardiectomy in Patients with Constrictive Pericarditis: A Retrospective Study from China.

PURPOSE: Pericardiectomy is the definitive treatment option for constrictive pericarditis and is associated with a high prevalence of morbidity and mortality. However, information on the associated outcomes and risk factors is limited. We aimed to report the mid-term outcomes of pericardiectomy from a single center in China. METHODS: We retrospectively reviewed data collected from patients who underwent pericardiectomy at our institute from April 2018 to January 2023. RESULTS: Eighty-six consecutive patients (average age, 46.1 ± 14.7 years; 68.6 men) underwent pericardiectomy through midline sternotomy. The most common etiology was idiopathic (n = 60, 69.8%), and 82 patients (95.3%) were in the New York Heart Association function class III/IV. In all, 32 (37.2%) patients underwent redo sternotomies, 36 (41.9%) underwent a concomitant procedure, and 39 (45.3%) required cardiopulmonary bypass. The 30-day mortality rate was 5.8%, and the 1-year and 5-year survival rates were 88.3% and 83.5%, respectively. Multivariable analysis revealed that preoperative mitral insufficiency (MI) ≥moderate (hazard ratio [HR], 6.435; 95% confidence interval [CI] [1.655-25.009]; p = 0.007) and partial pericardiectomy (HR, 11.410; 95% CI [3.052-42.663]; p = 0.000) were associated with increased 5-year mortality. CONCLUSION: Pericardiectomy remains a safe operation for constrictive pericarditis with optimal mid-term outcomes.

A novel multi-task machine learning classifier for rare disease patterning using cardiac strain imaging data.

To provide accurate predictions, current machine learning-based solutions require large, manually labeled training datasets. We implement persistent homology (PH), a topological tool for studying the pattern of data, to analyze echocardiography-based strain data and differentiate between rare diseases like constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). Patient population (retrospectively registered) included those presenting with heart failure due to CP (n = 51), RCM (n = 47), and patients without heart failure symptoms (n = 53). Longitudinal, radial, and circumferential strains/strain rates for left ventricular segments were processed into topological feature vectors using Machine learning PH workflow. In differentiating CP and RCM, the PH workflow model had a ROC AUC of 0.94 (Sensitivity = 92%, Specificity = 81%), compared with the GLS model AUC of 0.69 (Sensitivity = 65%, Specificity = 66%). In differentiating between all three conditions, the PH workflow model had an AUC of 0.83 (Sensitivity = 68%, Specificity = 84%), compared with the GLS model AUC of 0.68 (Sensitivity = 52% and Specificity = 76%). By employing persistent homology to differentiate the "pattern" of cardiac deformations, our machine-learning approach provides reasonable accuracy when evaluating small datasets and aids in understanding and visualizing patterns of cardiac imaging data in clinically challenging disease states.

Constrictive physiology is not present in all dogs with idiopathic chylothorax.

OBJECTIVE: To determine whether subtotal pericardectomy affects recurrence and long-term outcomes in dogs with idiopathic chylothorax (IC). ANIMALS: 12 client-owned dogs diagnosed with IC between July 26, 2016, and March 23, 2023. METHODS: The diagnosis of constrictive physiology (CP) was established with cardiac catheterization and defined as elevated and equal diastolic pressures in all 4 cardiac chambers. Dogs were then entered into the constrictive physiology (CP) group or non-CP (NCP) group. All dogs received at least a thoracic duct ligation (TDL). The dogs in the CP group had a subtotal pericardectomy performed in addition to TDL. Repeated surgical interventions, recurrence, long-term outcomes, and survival times were recorded. RESULTS: 8 dogs were entered into the CP group and underwent TDL and subtotal pericardectomy. Four dogs were entered in the NCP group and underwent only a TDL. Four dogs in the CP group and 1 in the NCP group required multiple surgeries for recurrent chylothorax. The 1-, 2-, and 3-year disease-free rates were, respectively, 100%, 100%, and 50% for the NCP group and 87.5%, 72.9%, and 72.9% for the CP group (P = .935). The 1-, 2-, and 3-year survival rates were, respectively, 100%, 100%, and 100% for the NCP group and 87.5%, 72.9%, and 72.9% for the CP group (P = .317). CLINICAL RELEVANCE: Constrictive physiology should be evaluated by cardiac catheterization before surgical treatment of IC in dogs. If CP is not diagnosed, subtotal pericardectomy may not be required.