Cardiovascular Surgery
Modified Bicaval Technique in Orthotopic Heart Transplantation ― Comparison With Conventional Bicaval Technique ―
2019 年 83 巻 1 号 p. 117-121
詳細
2019 年 83 巻 1 号 p. 117-121
Background: Orthotopic heart transplantation (HT) is the treatment of choice for patients with end-stage heart failure (HF). The bicaval technique was introduced as a safe alternative minimizing modification of atrial geometry. The modification of bicaval anastomosis is suggested to compensate for caliber mismatch and small donor. The present study was performed to compare these 2 techniques in terms of postoperative CT scan and clinical outcomes.
Methods and Results: Retrospectively, 158 consecutive patients with end-stage HF underwent orthotopic HT between January 2009 and June 2013 were analyzed. Of these, we excluded 3 patients with total HT. The study group was divided into modified technique (n=37) or conventional technique (n=118). A total of 113 patients (modified: n=29, conventional: n=84) were examined with cardiac CT. Discrepancy in the size of the vena cava compared with that of the anastomosis site was assessed. There was no significant difference in the complication and survival rates. There was 1 incident of moderate-to-severe tricuspid valve regurgitation in the modified group (n=1, 2.7%). Both the SVC ratio (1.07±0.13 vs. 1.28±0.32, P=0.001) and IVC ratio (1.06±0.07 vs. 1.13±0.19, P=0.009) were higher in the conventional group, which meant more stenotic imaging findings were observed in the conventional group.
Conclusions: Orthotopic HT with modified bicaval anastomosis is an attractive alternative with easy orientation and equivocal outcomes.
Orthotopic heart transplantation (HT) is the treatment of choice for patients with end-stage heart failure (HF). Ever since Lower et al first described the biatrial surgical technique, it has been the gold standard.1 Dreyfus et al subsequently introduced total HT, which enables the preservation of atrial anatomy and atrioventricular valve function.2 However, total HT is a longer, more technically demanding operation and cannot be performed when there is concomitant lung donation. Therefore, the bicaval technique was introduced as a safe alternative that minimizes atrial geometry modification.1,3 The advantage of the bicaval technique over the biatrial technique with regard to hemodynamics and sinoatrial node function has been described in several studies.4–6 However, some have indicated that the bicaval technique can lead to significant stenosis of the caval anastomosis.7,8 Modification of the bicaval anastomosis was introduced as an alternative to the conventional technique to compensate for caliber mismatch and create less stricture.9 This study aimed to investigate the clinical differences between the 2 techniques.
Between January 2009 and June 2013, 158 consecutive patients underwent orthotopic HT at Asan Medical Center, Seoul, Korea. Of these, 3 patients who underwent total HT were excluded. The patients were divided into 2 groups: 37 who underwent the modified bicaval procedure and 118 who underwent the conventional bicaval procedure.
HT was performed by 3 chief cardiac surgeons (A, B and C) according to the duty schedule. Selection of transplantation technique was based on each surgeon’s preference. Surgeon A used the modified bicaval technique (n=37) whereas surgeon B (n=70) and surgeon C (n=48) used the conventional bicaval technique. There was potential for technical differences between surgeons, but they all had sufficient experience prior to the study period, including more than 200 cases of open heart surgery and 20 cases of HT each year with good outcomes.
Surgical TechniquesThe donor heart was harvested in the usual manner, as previously described.10 The conventional bicaval technique was performed as described by Sarsam et al.3 In the modified technique, recipient cardiectomy was performed, leaving the left atrial cuffs. Most of the right atrial wall was then excised, leaving a strip of the right atrial posterior wall as bridging tissue between the superior and inferior venae cavae (Figure 1). Caval anastomosis was performed after adjusting the donor caval length. The donor left atrium, aorta and pulmonary arteries were sutured in the usual manner.
Intraoperative image of left atrial cuffs in the modified bicaval technique. IVC/SVC, inferior/superior vena cava.
The preoperative immunosuppressive protocol contained anti-interleukin2 receptor monoclonal antibody (anti-IL2 R mAb), with 1.5–2.0 g oral mycophenolate mofetil. Intravenous methylprednisolone (500 mg) was administered intraoperatively. After surgery, 1–2 g/day mycophenolate mofetil and anti-IL2 R mAb were administered to maintain the white blood cell count in the range of 4,000–6,000/μL. The trough FK 506 levels were maintained at 10–15 ng/mL during the 1st year and 6–8 ng/mL thereafter. Three injections of 125 mg methylprednisolone were administered over 24 h (1 injection every 8 h). The initial postoperative prednisone dose was 1 mg/kg/day, which was reduced to 0.25 mg/kg/day after 1 month and to 0.1 mg/kg/day after 1 year. If possible, prednisone was discontinued at 1 year after transplantation.
Follow-upThe mean follow-up duration was 55.7±17.6 (range, 1–90) months. All patients were examined using transthoracic echocardiography (TTE). Tricuspid regurgitation (TR) was evaluated using the apical 4-chamber view and was scored as none (0), trace/trivial (1+), mild (2+), moderate (3+), and severe (4+). Significant TR was defined as moderate regurgitation or worse.
Early graft failure was defined as low cardiac output syndrome with a need for retransplantation. Acute renal failure was defined as an abrupt and sustained decrease in kidney function, with a requirement for continuous renal replacement therapy. Mechanical circulatory support included extracorporeal membrane oxygenation and ventricular assist devices.
A total of 113 patients was examined using cardiac computed tomography (CT) with intravenous contrast for evaluation of the anastomosis 1 month before discharge. One reviewer (first author), who was blinded to all clinical data, analyzed all of the CT images. The superior vena cava (SVC) diameter (A), anastomosis site diameter (B), inferior vena cava (IVC) diameter (C), and anastomosis diameter (D) were measured, and ratios for the diameter sizes were calculated.
Discrepancy in the size of the vena cava compared with that of the anastomosis site was assessed as the ratio between both parameters (SVC ratio, A/B; IVC ratio, C/D) (Figure 2). A second blinded reviewer (radiology staff) measured the diameters again to confirm the accuracy of the diameter measurements.
Measurement of superior vena cava ratio (A/B) and inferior vena cava ratio (C/D) on cardiac computed tomography. (1,3) Conventional bicaval technique; (2,4) modified bicaval technique.
Cardiac CT was performed using a 2nd-generation dual-source CT system (Somatom Definition Flash; Siemens Healthcare, Erlangen, Germany). Images were acquired after injecting 60–80 mL of iomeprol-400 (Iomeron; Bracco Imaging, Milan, Italy) using the bolus-tracking technique. Retrospective ECG-gated scanning with pulsing (20–70%) was performed with a body size-adaptive protocol based on the patient’s body size. The mean estimated radiation effective dose was 8.7 mSv.
Clinical follow-up was performed in the outpatient clinic. All data regarding deaths were obtained from the Korean National Registry of Vital Statistics.
Statistical AnalysisCategorical variables are presented as percentages or frequencies, and continuous variables are expressed as mean±standard deviation. The variables for the 2 groups were compared using Student’s t-test. Kaplan-Meier curves were used to describe overall survival, and the differences in these rates between groups were assessed using the log-rank test. A P value <0.05 was considered to be significant. Statistical analysis was conducted using the IBM SPSS 21 software (IBM SPSS Statistics for Windows, Version 21.0. IBM Corp., NY, USA).
The preoperative baseline characteristics of both study groups are compared in Table 1. Compared with the conventional group, the modified group had shorter cardiopulmonary bypass and total ischemic times and was more likely to have chronic renal failure. There was no significant difference between the 2 groups.
| Modified bicaval |
Conventional bicaval |
P value | |
|---|---|---|---|
| Patients, n | 37 | 118 | |
| Age (R), years | 49.1±12.8 | 48.6±13.1 | 0.83 |
| Age (D), years | 34.4±10.9 | 34.9±10.1 | 0.83 |
| Male sex (R), n (%) | 25 (67.6%) | 82 (69.5%) | 0.55 |
| Male sex (D), n (%) | 29 (80.6%) | 100 (84.7%) | 0.83 |
| Body weight (R), kg | 59.6±10.2 | 61.5±14.0 | 0.37 |
| Body weight (D), kg | 66.5±11.0 | 68.1±12.8 | 0.45 |
| Height (R), cm | 165.4±8.6 | 166.2±8.2 | 0.63 |
| Height (D), cm | 171.2±8.4 | 171.2±7.8 | 0.99 |
| BSA | 1.65±0.2 | 1.68±0.2 | 0.43 |
| Diabetes mellitus, n (%) | 4 (10.8%) | 22 (18.6%) | 0.27 |
| Hypertension, n (%) | 7 (18.9%) | 12 (10.2%) | 0.16 |
| PVD | 2 (5.6%) | 2 (1.7%) | 0.20 |
| CVA | 2 (5.6%) | 9 (7.6%) | 0.65 |
| COPD | 2 (5.6%) | 4 (3.4%) | 0.58 |
| Preoperative admission | 22 (59.5%) | 65 (55.1%) | 0.64 |
| Preoperative ICU | 4 (10.8%) | 15 (12.7%) | 0.76 |
| Preoperative inotrope use | 17 (45.9%) | 66 (55.9%) | 0.29 |
| Preoperative ECMO/VAD | 2 (5.4%) | 9 (7.6%) | 0.65 |
| Preoperative ventilator | 2 (5.4%) | 12 (10.2%) | 0.38 |
| CRF, n (%) | 6 (16.2%) | 7 (5.9%) | 0.05 |
| Pulmonary hypertension | 42.2±15.6 | 44.1±15.4 | 0.53 |
| TV pressure gradient | 36.5±15.8 | 39.1±15.4 | 0.38 |
| Total ischemic time | 142.7±69.0 | 165.6±57.3 | 0.05 |
| CPB time | 119.9±50.4 | 184.2±256.4 | 0.01 |
BSA, body surface area; COPD, chronic obstructive pulmonary disease; CPB, cardiopulmonary bypass; CRF, chronic renal failure; CVA, cerebrovascular accident; D, donor; ECMO, extracorporeal membrane oxygenation; ICU, intensive care unit; PVD, peripheral vascular disease; R, recipient; TV, tricuspid valve; VAD, Ventricular assist device.
The 30-day, 1-year, and 5-year survival rates were 98.1%, 96.1%, and 89.7%, respectively. There were 3 in-hospital deaths: cerebral hemorrhage (n=2) and sepsis (n=1). The 30-day, 1-year, and 5-year survival rates were 97.3%, 97.3%, and 87.9%, respectively, in the modified group compared with 98.3%, 96.6%, and 90.3%, respectively, in the conventional group. Kaplan-Meier curves for estimated survival that compared both groups showed no significant differences (Figure 3).
Kaplan-Meier curves for survival comparison after surgery using conventional or modified bicaval heart transplantation technique.
Postoperative complications are presented in Table 2. There was no significant difference in complication rates after surgery. Only 1 patient in the modified group was diagnosed with atrial fibrillation.
| Variable | Modified | Conventional | P value |
|---|---|---|---|
| Patients, n | 37 | 118 | |
| Early graft failure, n (%) | 0 (0%) | 1 (0.8%) | 0.57 |
| Bleeding, n (%) | 3 (8.1%) | 6 (5.1%) | 0.49 |
| Acute renal failure, n (%) | 3 (8.1%) | 15 (12.7%) | 0.45 |
| MCS, n (%) | 4 (10.8%) | 6 (5.1%) | 0.22 |
| Early stroke, n (%) | 0 (0%) | 3 (2.5) | 0.33 |
| Atrial fibrillation, n (%) | 1 (2.8%) | 0 (0%) | 0.07 |
MCS, mechanical circulatory support.
Echocardiographic evaluation revealed that the left atrium was larger in the modified group than in the conventional group (51±9.6 vs. 45±9.4, P=0.003). There was one incident of moderate-to-severe tricuspid valve regurgitation in the modified group (n=1, 2.7%) (Table 3). In this patient, initial TTE findings suggested a trivial TR grade with minimal pericardial effusion. However, pericardial thickening with constrictive physiology was found 1 month after surgery. Significant TR (+3) occurred in the 8th postoperative month because of late-onset constrictive pericarditis. The patient died from combined severe coronary artery disease in the 2nd postoperative year.
| Variables | Modified bicaval |
Conventional bicaval |
P value |
|---|---|---|---|
| Echocardiographic data, n | 36 | 116 | |
| Echo follow-up, months | 56.0±18.9 | 53.9±18.6 | 0.55 |
| LVID end-systolic, mm | 28±5.6 | 28±5.1 | 0.90 |
| LVID end-diastolic, mm | 44±5.3 | 45±5.3 | 0.45 |
| LA, mm | 51±9.6 | 45±9.4 | <0.01 |
| LVEF, % | 62±7.2 | 63±5.2 | 0.81 |
| Peak TR velocity, m/s | 2.3±0.3 | 2.2±0.3 | 0.56 |
| TR, n (%) | |||
| Grade I | 34 (91.9%) | 113 (95.8%) | |
| Grade II | 1 (2.7%) | 3 (2.5%) | |
| Grade III | 1 (2.7%) | 0 | |
| Computed tomography, n | 29 | 84 | |
| SVC ratio (SVCR) | 1.07±0.13 | 1.28±0.32 | <0.01 |
| IVC ratio (IVCR) | 1.06±0.07 | 1.13±0.19 | <0.01 |
IVC, inferior vena cava; LA, left atrium; LVEF, left ventricular ejection fraction; LVID, left ventricular internal diameter; SVC, superior vena cava; TR, tricuspid valve regurgitation.
Both the SVC ratio (1.07±0.13 vs. 1.28±0.32, P=0.001) and the IVC ratio (1.06±0.07 vs. 1.13±0.19, P=0.009) were high in the conventional group, implying that more stenotic imaging findings were observed in this group. However, there were no episodes of anastomosis site stenosis that required intervention.
Orthotopic HT is the treatment of choice for patients with end-stage HF.1–3 Significant advances have been made in preoperative and postoperative management of transplantation treatments, particularly immunosuppression treatment. However, operative techniques for HT have not changed significantly.11 The advantages of the conventional bicaval technique include lower incidence of sinus node dysfunction and well-maintained atrial architecture and function compared with the biatrial technique.6,12 However, when the SVC and IVC are transected for bicaval anastomosis, there are potential risks of shrinkage and retraction. In addition, in the presence of snares for caval drainage cannulation, the anatomical orientation can be lost, potentially resulting in a twisted or kinked anastomosis with excessive suture line tension.
Our results demonstrated the influence of the surgical technique on venous anastomosis and postoperative outcomes after HT. We did not find any significant differences in the postoperative survival rate or the occurrence of significant TR. The possible explanation for this result is that the modified bicaval procedure is the same as the conventional procedure in terms of atrial architecture. Thus, we considered that there were no adverse effects of leaving a strip of the right atrial posterior wall attached.
Several reports insist that the modified technique can prevent technical disadvantages such as shrinkage, retraction, and distortion of the venae cavae, which are encountered with the conventional technique.9,13 CT revealed the ratio between the vein and anastomosis site was close to 1:1 in the modified group, which suggested that the modified technique created a better anastomosis site. Late anastomotic stricture may also be less frequent with the modified technique because the anastomosis can be performed without tension or kinking. In addition, it is easier to adjust the length of the atrial excision to the donor organ, particularly when it is smaller than that of the recipient.
Study LimitationsSpecifically, the retrospective nature of the analysis and the lack of postoperative CT data for some patients. The selection of the surgical strategy was the preference of the surgeon and the modified bicaval technique was performed by a single surgeon, which may limit generalization of our results. Moreover, the evaluation was based on CT data and not clinical outcomes such as strictures that required intervention.
In conclusion, orthotopic HT with a modified bicaval anastomosis represents an attractive alternative to the conventional bicaval technique, with easy orientation and equivocal outcomes.
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