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The bidirectional Glenn (BDG) shunt operation serves as temporary treatment of single-ventricle physiology before the eventual Fontan procedure. Some cases can be performed without the support of a cardiopulmonary bypass (CPB) machine. In this study, we present the surgical outcomes of off-pump BDG operations with the use of temporary veno-atrial shunt to decompress the superior vena cava (SVC) during clamping.
JOURNAL OF MEDICAL RESEARCH BIDIRECTIONAL GLENN OPERATION WITHOUT CARDIOPULMONARY BYPASS: OPERATIVE PROTOCOL AND EARLY RESULTS Nguyen Tran Thuy¹, Ngo Thi Hai Linh¹, Doan Quoc Hung² ¹Cardiovascular Center, E Hospital ²Hanoi Medical University The bidirectional Glenn (BDG) shunt operation serves as temporary treatment of single-ventricle physiology before the eventual Fontan procedure Some cases can be performed without the support of a cardiopulmonary bypass (CPB) machine In this study, we present the surgical outcomes of off-pump BDG operations with the use of temporary veno-atrial shunt to decompress the superior vena cava (SVC) during clamping From June 2013 to June 2015, 23 patients underwent off-pump BDG operations at Cardiovascular Center, E Hospital All patients were operated on using a venoatrial shunt to decompress the SVC Satisfactory results with mean oxygen saturation increased from 79.6 ± 11.2 % to 87.2 ± 4.7 % The superior vena cava (SVC) clamping time was 14 ± 2.4 minutes (ranging from 12 to 21 minutes) No neurological complications or deaths occurred after the surgery and the postoperative period was uneventful In conclusion, the use of venoatrial shunt to decompress SVC during the off-pump BDG operation is safe and produces good surgical outcomes Its wider adoption can the deleterious effects associated with CPB The operation is easily reproducible at low cost and overcome Keywords: congenital heart disease, bidirectional Glenn operation, without cardiopulmonary bypass I INTRODUCTION Bidirectional Glenn shunt operation is performed as the initial step in the treatment of functional single-ventricle physiology before the completion of the Fontan procedure The purpose of this surgery is to provide balanced venous blood flow into two pulmonary arteries for oxygenation, as Corresponding author: Nguyen Tran Thuy, E Hospital Email: drtranthuyvd@gmail.com Received:09 May 2017 Accepted: 16 November 2017 JMR 111 E2 (2) - 2018 oppoed to providing mixed ateriovenous blood, as in the Blalock – Taussig shunt surgery (aortopulmonary shunt) [1 - 3] Off-pump BDG operations without a temporary shunt to decompress the SVC will cause an elevation in the cerebral blood volume, leading to increased intracranial pressure and eventually, thereby, brain reduced blood flow to the brain and damage [3; 4] The BDG operation is conventionally performed with the support of CPB at the expense of higher cost and disadvantages 75 JOURNAL OF MEDICAL RESEARCH of CPB Therefore, globally, there has been a variety of reports on BDG operations without CPB [1; 5; 6] The have show that in offpump BDG operation, pulmonary arterial pressure is lower and the hospital length of stay of off-pump group is shorter than that of the on-pump group [7; 8] However, there have been no official reports on this issue in Vietnam In this study, we present the surgical protocol to perform off-pump BDG operation using the SVC-RA pressure lowering system and present early outcomes of this newly applied technique [9], [10] II SUBJECTS AND METHODS Subjects Subjects were patients who had attributes suitable for BDG operation, without any intracardiac defects requiring correction including: pulmonary artery-plasty, atrial septal extension, atrioventricular valvuloplasty, etc Methods The study disign was a retrospective observational study Patients were prepared for the survey through the following steps: - Physical examination: Clinical symptoms (evaluating the severity of heart failure, using the NYHA classification, and the level of cyanosis), SpO2, and medical history - Laboratory tests: + Routine blood tests, electrocardiography, and chest x-ray + Echocardiography: evaluate left ventricular function, abnormal wall motion, 76 chamber size, the functional status of the heart valves, pulmonary artery (PA) size + Cardiac catheterization: measure PA size, anatomy, pressure and resistance - Definitive diagnosis was established based on the following: physical examination, Doppler echocardiography, cardiac catheterization, blood tests, electrocardiography and chest x-ray - Surgical consultation, hospital admission, and preoperative medical therapy - When all conditions had been assured, the patients underwent surgery according to the same protocol in anesthesia, operative techniques, and postoperative resuscitation In the operating room, hemodynamic parameters were recorded - Technical procedure: + General anesthesia, intubation Premedication with Midazolam, Fentanyl, Rocuronium Patients were on controlled mechanical ventilation with Vt = 150 ml and the respiratory rate of 18 per minute The anesthesia was maintained by Isoflurane, Fentanyl, and Rocuronium A femoral vein catheter was placed for drug distributions and monitoring of the right atrial pressure A right internal jugular vein catheter was inserted for SVC pressure monitoring An invasive arterial pressure line was also placed - Surgical steps: + Whole body antiseptic application, from the chest to the legs; + Median sternotomy; + Dissect the SVC and ligate the azygos vein; + Dissect the right branch of PA, and measure PA pressure; JMR 111 E2 (2) - 2018 JOURNAL OF MEDICAL RESEARCH + Set up the system to decrease SVC-PA pressure + Trial right PA clamp for several minutes to check the changes in transcutaneous oxygen saturation (SpO2) Systemic heparin with the dose of mg/kg to achieve the ACT of more than 200 seconds Set up the system to decrease SVC-PA pressure with the head of the patients elevated 15 degrees, inject methylprenisolone (20 mg/ kg) intravenously, SVC clamp to anstomose with right PA, maintain the difference between mean arterial pressure and mean SVC pressure during clamping higher than 40 mmHg During surgery, hemodynamic stability was maintained by fluid replacement and inotropes: adrenaline 0.1 mcg/kg/min and Milrinone 0.3 mcg/kg/min + Make end-to-side SVC-PA anastomosis by 7.0 prolene suture + Remove cannulae, achieve hemostasis, insert drains, electrodes, close the pericardium if possible + Close the sternotomy by steel suture, soft tissue was closed using running suture or interrupted absorbable suture in patients with high risks of infection + In the intensive care unit, an echocardiography, routine laboratory tests (complete blood count, electrolytes, arterial blood gases, ) were done All complications and actions taken were recorded + After the ICU stay, patients were transferred to Pediatric Cardiology Department for further treatment until discharge Ethics All study procedures complied with the ethical principles of biomedical research Participants consented to take part in the study and were told that they could withdraw at any time Participants’ information was kept secure and confidential III RESULTS From June 2013 to June 2015, we performed off-pump BDG operation on 23 patients The mean SVC clamp time was 14 ± 2.4 minutes (ranged from 12 - 21 minutes) During clamping, the mean central venous pressure ranged from 24 to 40 mmHg (average 31.5 ± 6.1 mm Hg) Preoperative PA pressure ranged 11 - 25 mmHg (average 16.3 ± 3.2 mmHg) There was no conversion to CPB machine Indications of patients undergoing BDG operations are summarized in Table Table Indications of patients undergoing BDG operations Other surgeries Patients (n) Percent (%) Single-ventricle physiology 11 47.8 Double outlet right ventricle with transposition of the great arteries 21.7 Transposition of the great arteries, pulmonary stenosis, large ventricular septal defect 26.2 Atrioventricular disassociation, double outlet right ventricle 4.3 JMR 111 E2 (2) - 2018 77 JOURNAL OF MEDICAL RESEARCH Early results The mean ventilator time after surgery was 2.6 ± 1.2 hours (1 - hours), the ICU length of stay was 13.2 ± 3.1 (10 - 18 hours); no death occurred Echocardiography evaluation at discharge showed no anastomosis stenosis, and postoperative electrocardiography (ECG) revealed no arrhythmia Mean postoperative PA pressure was 13.6 ± 2.5 mmHg Table Postoperative complications Complications Patient (n) Percent (%) Chylothorax 4.3 Pneumonia 8.6 Pulmonary effusion requires drainage 4.3 Surgical wound infection 4.3 Reoperation 4.3 Neurological deficits 0 Reoperation due to thrombus at the Glenn anastomosis Table Pre and postoperative Hct, SpO2 Parameters Preoperative Postoperative p Hct (%) 0.53 ± 0.11 0.43 ± 0.05 0.001 SpO2 (%) 79.96 ± 11.2 87.2 ± 4.7 0.011 The hospital length of stay ranged from to days (average 7.1 ± 1.3 days) Echocardiography showed no significant pressure gradient through the SVC-RPA anastomosis and also showed good velocity of blood flow; ECG showed normal sinus rhythm in all patients, and no neurological complications were recorded IV DISCUSSION Several studies have documented the decrease in oxyhemoglobin in brain tissue, a 50% reduction in blood flow in the middle cerebral artery with significant changes 78 in encephalography Rodriguez found that clamping the SVC decreases the systolic pressure of cerebral arteries and subsequently decreases the brain's oxygen supply [2 - 4] To avoid these complications many studies have reports on the used a temporary shunt to decompress the SVC and improve perfusion of the brain Table is summary of all studies in the past 15 years examining BDG operations without CBP Lamberti polished his research on seven patients in 1990 and subsequently, there was a series of other studies examining off-pump BDG surgery [1; 5; 9] JMR 111 E2 (2) - 2018 JOURNAL OF MEDICAL RESEARCH Table Studies on off-pump BDG surgery Study Year Number of study patients Temporary shunt Lamberti 1990 SVC – RA Lal 1996 SVC – RA Murthy K S 1999 SVC – PA Jahangiri 1999 No Villagra F 2000 No Tiereli 2003 30 SVC – RA/PA Maddali 2003 SVC – RA Liu 2004 20 SVC – RA/PA Luo 2004 36 SVC – RA Maeba 2006 18 SVC – RA/PA Kotani 2006 14 SVC – RA Hussain 2007 22 No Kandakure 2010 218 SVC – RA 13 studies 389 Total RA: right atrium; PA: pulmonary artery; SVC: superior vena cava (Until now, there have been no official reports on this technique in Vietnam) In the study of Ulisses Alezandre Crotti, the mean age of on-pump group was 66 months and that of off-pump group was 50 months (p = 0.17 using Mann-Whitney test) This suggests the differences in age, gender, weight, types of defects between on-pump and off-pump group are not important factors in choosing the use of peripheral circulation The choice of a temporary shunt depends on the experience and ability of the surgeons, and anesthegist, as well as the conditions of the surgical center Our technique uses a temporary veno-atrial shunt with the following steps: placing a venous graft at the junction of SVC and azygos vein, which effectively decreases the pressure of the clamped SVC and avoids the possibility of SVC stenosis In addition, the head-elevated position during operation facilitates the adequate decompression of SVC and provides enough space surgical JMR 111 E2 (2) - 2018 79 JOURNAL OF MEDICAL RESEARCH Figure Description of a veno-atrial shunt used in our technique SVC: superior vena cava; RPA: right pulmonary artery; LPA: left pulmonary artery; RA: right atrium According to our experiences, with the veno-atrial shunt, SVC pressure after clamping did not exceed 40 mmHg Postoperative chylothorax and dysfunction of the diaphragm occured at low incidences because, with our technique, the dissect on field of SVC was short; avoids and the injury to phrenic nerve and the refocus surrounding lymphatics Performing Glenn operation on patients who already have a Blalock – Taussig shunt or patent arteriosus ductus (PAD) is more convenient as the aortopulmonary shunt continuously supplies blood for the lungs during the reconstruction of Glenn anastomosis and maintains the good stable oxygen saturation The choice of SVC and atrial cannula size were based on the size of the patients SVC and right atrium, and patient’s weight, skin area in CPB During surgery, the cooperation between 80 surgeons and anesthetist is key to a successful off-pump BDG operation [6] During SVC clamping, the blood flow to the brain is reduced; therefore, to maintain good cerebral perfusion during off-pump BDG surgery, the authors proposed the concept of transcranial pressure, which is the difference between mean aterial pressure and mean SVC pressure during SVC clamping (transcranial pressure = mean arterial pressure – central venous pressure) [7] This pressure has to be maintained at a minimum of 30 mmHg during SVC clamping to assure adequate cerebral perfusion Veno-atrial shunt reduced SVC pressure and improved cerebral perfusion [3; 4] Monitoring of parameters of brain function to provide additional information about hemodynamic effects of SVC clamping on brain tissue transcranial Doppler ultra- JMR 111 E2 (2) - 2018 JOURNAL OF MEDICAL RESEARCH sound, near-infrared spectroscopy, and encephalography [6] However, these tests were not available during this study so the authors monitored brain function by assessing mean arterial pressure and central venous pressure Corticosteroid was used to minimalize brain edema and neurological insults Body temperature was kept at approximately 33 - 34⁰C in order to reduce the metabolism of brain cells and adjust for the reduced pressure of cerebral blood flow during SVC clamping Inotropes and crystalloid replacement were used to maintain adequate cerebral blood flow and a transcranial pressure higher than 30 mmHg during SVC clamping [8] Hypoxia was regulated by increasing fraction of inspiratory oxygen (FiO2), increasing mean arterial pressure by using inotropes, and providing enough circulating fluid and to improve blood flow Postoperative treatment to the lung decreas pulmonary vascular resistance and increas blood return to the SVC Pulmonary dilation medications (milrinone, iloprost ) helped to decrease pulmonary arterial pressure and end-diastolic left ventricular pressure [1] Prolonged mechanical ventilation time resulted in increased intrathoracic pressure and negatively affected the blood return to the SVC and blood flow through the shunt, early weaning and extubation helped circument these problems The mean time on ventilator in our study was 2.6 ± 1.2 hours (1 - hours), which is comparable to other studies [1] Short ventilatory time is also a big advantage of off-pump BDG operation compared to conventional JMR 111 E2 (2) - 2018 BDG surgery with CPB [2; 3; 12] The different factors in our study are comparable to those Crotti.The mean duration to extubation of the off-pump group was hours and that of on-pump group was 11 hours (p = 0.83) The mean length of stay in the ICH was days and days in the on-pump and off-pump group, respectively (p = 0.29) The average hospital length of stay of the former group was days, of the latter group was days, and of the whole study group was days In Mohamed, the off-pump group were extubated earlier, and had shorter length of stay in the ICU and shorter hospital length of stay than on-pump group In our study, all cases had shunts that supplied blood to the lungs; and the patent arteriosus ductus, collaterals, aortopulmonary shunt (Blalock-Taussig) had the shunt ligated to avoid the increased left ventricular after load, improve cardiac function, and decrease the severity of atrioventricular valve regurgitation [9] Mean postoperative pulmonary arterial pressure was 13.6 ± 2.5 mmHg, which was the ideal pressure after BDG operation According to Tables and 4, the oxygen saturation was significantly improved after surgery (p < 0.011) and the hematocrit decreased substantially postoperatively (p < 0.001) In 23 study participants, there were six cases with early postoperative complications, which accounted for 26.1% of the total sample (Table 2), and only one cases with more than one complication According to Chang [9], the incidences of postoperative complications, such as superior vena cava syndrome, low cardiac output syndrome, arrhythmia, were high, while in research in our center and by oth81 JOURNAL OF MEDICAL RESEARCH er authors [10], the incidences of the above mentioned complications were very low There were no case requiring reoperation in our study; in other research the rate of this complication was 6% There was a case requiring reoperation; especially three days after BDG surgery, facial edema occurred and echocardiography revealed thrombi inside SVC In reoperation, we found that there were thrombi along the central venous catheter and at the Glenn anastomosis The thrombi were removed and the central venous catheter was replaced The reason for this thrombi formation may be from in the previous surgery, during the separation of SVC when we cut a part of the central venous catheter that lies in right atrium (Catheter which is too long will cause the difficulty for operation and cannot measure SVC pressure), In general, the incidences of postoperative complications in our study are comparable or lower than other studies [11; 12] In our study, there were no deaths in offpump group and two deaths in the on-pump group There were no cases with chylothorax in the off-pump group, but eight patients in the on-pump group suffered from this complication Only two patients in off-pump group had early complications, while 14 patients in the on-pump group did One advantage of the Glenn procedure without peripheral circulation is the significant reduction in post surgical complications compared to on-pump group Our results are comparable to those of Mohamed’s study The rates of hemorrhage requiring reoperation in two groups are significantly different (p = 0.044); the rate of chylothorax in on-pump group is 82 significantly higher than that of the off-pump group (p < 0.01) The early mortality rates of on-pump and off-pump groups are 0% and 4%, respectively The causes of death in on-pump group were low cardiac output syndrome, heart failure, and neurological complications Comparing the results from this study, to ours the off-pump group had better postoperative recovery, shorter time on mechanical ventilator, shorter length of stay in the ICU and hospital, and fewer post surgical complications compared to those undergroing the on-pump Glenn procedure Without the CPB machine, patients can avoid unwanted effect including: increased pulmonary vascular resistance, blood dilution, air embolism and a host of other undesirable effects Tireli [13] 2003, confirmed that in the off-pump BDG operation, pulmonary arterial pressure was lower and the hospital length of stay of off-pump group was shorter than the those of on-pump group All patients were on heparin in the first 24 hours, and aspirin was used subsequently Patients were monitored regularly, and all of them maintained good oxygen saturation; no neurological complications occurred Reducing medical cost a global priority According to Hussain (2007), the cost of an on-pump BDG surgery is 1200 USD and that of an off-pump BDG operation is only 250 USD [8] To date, the cost of a BDG shunt institution with CPB (49 million VND) is times higher than that of the same operation without CPB (7 million VND) at our Cardiovascular Center The off-pump BDG operation technique reduced cost by omitting use of CPB, reducing use of blood products and JMR 111 E2 (2) - 2018 JOURNAL OF MEDICAL RESEARCH reducing the suctioning system after sterilization Postoperative period and hospital length of stay were shorter, and the rates of pulmonary effusion, chylothorax and diaphragm paralysis were lower Lastly no neurological complications were documented V CONCLUSION After performing off-pump BDG shunt institution in 23 patients from June 2013 to June 2015, at Cardiovascular Center - E Hospital, we concluded that off-pump BDG operation using veno-atrial shunt to decompress the SVC was safe, and produced satisfactory surgical outcomes This technique can avoid the disorders caused by CPB, significantly improve oxygen saturation, and the quality of life, and reduce mortality rate after Fotan procedure Acknowledgements I would like to express my deepest gratitude to the Cardiovascular Center, E Hospital for supporting us in the data collection process REFERENCES A K D P R Kandakure (2012) Venoatrial Shunt-Assisted Cavopulmonary Anastomosis Asian Cardiovasc Thorac Ann, 18, 569 – 573 L Y Liu J, Chen H, Shi Z, Su Z, Ding W (2004) Bidirectional Glenn procedure without cardiopulmonary bypass Ann Thorac Surg, 77, 1349 – 1352 W N Rodriguez RA, Cornel G (2000) Should the bidirectional Glenn procedure be better performed through the JMR 111 E2 (2) - 2018 support of cardiopulmonary bypass? 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Juneja (2007) The bidirectional cavopulmonary (Glenn) shunt without cardiopulmonary bypass: is it a safe option? Interact CardioVascThorac Surg, 6, 77 - 82 C A e al (1993) Early bidirectional cavopulmonary... admission, and preoperative medical therapy - When all conditions had been assured, the patients underwent surgery according to the same protocol in anesthesia, operative techniques, and postoperative