2.1 Characteristics of the population under study
During the study period, 829 patients underwent pericardiectomy; of them, 3 met the exclusion criteria, so a total of 826 patients were eligible and included in the study group.
2.1.1 Diagnosis of constrictive pericarditis
The diagnosis of constrictive pericarditis was made on the basis of clinical manifestation, echocardiography, chest computed tomography scan, cardiac catheterization, surgery, and pathological criteria. Typical symptoms and signs are a prominent change in the x and y descent in jugular venous pulse, dyspnea upon exertion, palpitations, abdominal distension, as well as edema in the ankles or legs. Echocardiography and chest computed tomography scan revealed a severely thickened or calcified pericardium and cardiac catheterization revealed elevated end-diastolic pressure and the “square root sign” of right ventricular pressure tracing. Surgical and pathological findings were reviewed to confirm the preoperative diagnosis. ( Figure 1- Figure 4) [8-10]
2.1.2 Surgical technique
Pericardiectomy was performed via sternotomy, the pericardium was removed between the two phrenic nerves and from the great vessels to the basal aspect of the heart. The pericardium was palpated to identify a relatively soft and uncalcified area after median sternotomy, and the thymus removed laterally. A #-shaped incision was made over the pericardium. Dissection was started at the base of the aorta, extended downwards to the lateral and posterior walls of the left ventricle, followed by the diaphragmatic pericardium. The pericardium over the right atrium and vena cava was resected last. If calcified plaques penetrating the epicardium were present, we left small “islands” of calcified pericardial tissue. Cardiopulmonary bypass was avoided during surgery except for concomitant valve replacement.
All survivors discharged from hospital were monitored to the end date of the study. At the outpatient department, all patients were investigated with echocardiogram, electrocardiogram, and X-ray chest film, once every 3 to 12 months. At the last follow-up, the patients were contacted by telephone or micro-massage or interviewed directly at the outpatient department.
2.2.1 Preoperative and operative data
826 consecutive patients undergoing pericardiectomy for constrictive pericarditis were included in the study. The patients were divided into two groups: group with multiorgan failure (n=86) and group without multiorgan failure (n=740) (Table 1 and Table 2 )
There were 66 operative deaths (66/826, 8.0%). The causes of operative deaths were multiorgan failure (86/826, 10.4%), including cardiogenic shock + AKI + ventricular fibrillation (15/86), cardiogenic shock +AKI (46/86), cardiogenic shock + AKI + hepatic failure + septicemia (10/86), cardiogenic shock + AKI + respiratory failure (15/86). (Table 6)
Preoperative CVP (25.0±0.4 versus 19.3±0.2 mmHg, P＜0.001) in group with multiorgan failure were significantly higher than that in group without multiorgan failure.(Table 2) 1 patient required extracorporeal membrane oxygenation.
Fluid balance on operation day （D0）of group with multiorgan failure were significantly less negative than that of group without multiorgan failure (-640.7±52.0 ml versus -1223.9±32.6 ml, P＜0.001). While fluid balance postoperative day D2 of group with multiorgan failure was significantly more negative than that of group without multiorgan failure (-1176.1±154.9 ml versus -478.9±20.9 ml, P＜0.001). Use of adrenaline of group with multiorgan failure were significantly higher than that of group without multiorgan failure (100% versus 25.9%, P＜0.001; 1.6±0.02 versus 0.02±0.01 μg/kg/min, P＜0.001; respectively ) (Table 3).
Chest drainage (1268.3 ± 85.7 versus 696.8 ± 13.8 ml, P＜0.001), and surgical duration (230.0 ± 5.7 versus 174.1 ± 2.1 mins, P＜0.001)，bleeding during operation (518.6 ± 28.4 versus 385 ± 11.9 ml, P＜0.001), blood lactate (12.5±0.5 versus 2.1±0.1 mmol/l, P＜0.001) of group with multiorgan failure were significantly more than those of group without multiorgan failure.
Table 4 showed the use of inotropic medication (n=826).
Postoperatively, CVP decreased statistically significantly（P＜0.001）, and LVEDD and LVEF improved statistically significantly（P＜0.001, P＜0.001; respectively (Table 5).
The common early postoperative complications included acute renal injury (222/826, 26.9%), long-term intubation time＞48h (393/826, 47.6%), and multiorgan failure (86/826, 10.4%). (Table 6)
2.2.2 Analysis of risk factors of early mortality after pericardiectomy
Univariate analysis of potential risk factors of LCOS showed that numerous factors are associated with multiorgan failure, including male (P＜0.001), time between symptoms and surgery (P＜0.001), thickness of pericardium (P＜0.001), intubation time (P＜0.001), ICU retention time (P＜0.001), hospitalized time postoperative (P＜0.001), preoperative central venous pressure (P＜0.001), postoperative central venous pressure (P＜0.001), D0 fluid balance (P＜0.001), D2 fluid balance (P＜0.001), postoperative chest drainage (P＜0.001), preoperative LVEDD(P＜0.001), postoperative LVEDD (P＜0.001), surgical duration (P＜0.001), bleeding during operation (P＜0.001), serum creatinine 24h after surgery (P＜0.001), serum creatinine 48h after surgery (P＜0.001), fresh-frozen plasma (P＜0.001), packed red cells (P＜0.001), blood lactate (P＜0.001), and tuberculosis pericarditis (P=0.003).
When they were included in multivariate analysis models, multivariate analyses also showed that numerous factors are associated with multiorgan failure, including male (P=0.006), time between symptoms and surgery (P＜0.001), thickness of pericardium (P＜0.001), intubation time (P＜0.001), ICU retention time (P＜0.001), hospitalized time postoperative (P＜0.001), preoperative central venous pressure (P＜0.001), postoperative central venous pressure (P＜0.001), D0 fluid balance (P＜0.001), D2 fluid balance (P＜0.001), postoperative chest drainage (P＜0.001), preoperative LVEDD(P＜0.001), postoperative LVEDD (P＜0.001), surgical duration (P＜0.001), bleeding during operation (P＜0.001), serum creatinine 24h after surgery (P=0.042), serum creatinine 48h after surgery (P＜0.001), fresh-frozen plasma (P＜0.001), packed red cells (P＜0.001), blood lactate (P＜0.001).
2.2.3 Histopathologic study results
Histopathologic studies of pericardium tissue from every patient were done. The diagnosis of tuberculosis was confirmed on the basis of clinical findings and histopathologic features, including the presence of typical granuloma and caseous necrosis, acid-fast bacilli in Ziel-Nelson tissue staining, and bacteriologic studies using the polymerase chain reaction (PCR) test on the pericardial fluid or tissue for evidence of mycobacterium tuberculosis.
In this series from Guangxi, China, characteristic histopathologic features of tuberculosis (434/826,52.5%) of pericardium were the most common histopathologic findings, and 260 patients (392/826,47.5%) had the histopathologic findings of chronic nonspecific inflammatory changes. (Figure 3, Figure 4)
2.2.4 Follow-up results
760 survivors were discharged from hospital and 684 patients were monitored to the end date of the study and the follow-up was 90.0% (684/760) completed. The mean duration of follow-up was 126.4 ± 3.5 months (range, 1 to 342), 7 late deaths (7/684, 1.0%) occurred 131, 193, 208, 210, 215, 240, and 300 months after being discharged from our hospital. 3 died of heart failure, 1 of cerebral hemorrhage, and 3 of unknown reason. The latest data of follow-up showed that 656 survivors were in NYHA class I (656/684, 95.9%) and 21 in class II (21/684, 3.1%). (Figure 5)