TECHNICAL TIPS FOR PAEDIATRIC CARDIOLOGY AND CARDIAC SURGERY-3 Continuous versus interrupted technique of Ventricular Septal Defect (VSD) closure in total correction for Tetrology
of Fallot Pertaining to Residal VSD Riffat Tanveer, Arif-ur-Rehman Khan, Tariq Azam Siddiqi, Sohail Siddique, Ameena Nasreen, Salman-ur-Rehman, Saad Badar National Institute of Cardiovascular Diseases (NICVD), Karachi. Abstract Objective: To analyze the outcome of continuous versus interrupted closure technique of ventricular septal defect (VSD) closure in Tetrology of Fallot with reference to postoperative residual VSD after total correction Methods: A randomised control study was conducted between January 2008 to December 2008 at The Department of Cardiac Surgery, National Institute of Cardiovascular Diseases (NICVD), Karachi. The results of total correction (T.C) of VSD in patients with Tetralogy of Fallot, with emphasis on the suturing technique and eventually on the occurrence of residual ventricular septal defect(VSD) were analyzed. Transventricular as well as transatrial route was used to approach VSD. In thirty patients VSD was closed with 5/0 proline continuous double ended suture while in remaining 30(50%) patients VSD was closed with interrupted 5/0 prolene double ended sutures. Postoperative echocardiography was done in all patients as a routine on second postoperative day, to document residual VSD. Results: The study included 60 (100%) patients with T.O.F. There were 20 (33.3%) females and 40 (66.6%) males with ages ranging between 04 to 18 years (mean 13.025 ± 2.123 years). Postoperative echocardiography showed residual VSD in 05 (8.3%) patients at posteroinferior rim of VSD. Of these 05 cases, in four VSD had been closed with continuous 5/0 proline double ended sutures, and one had VSD closed with interrupted 5/0 double ended sutures. Conclusion: Residual VSD is common with continuous suturing technique as compared to interrupted suturing technique. This is perhaps because of poor myocardium quality and higher RV pressures in our patients presenting at a late age. Small (less than 05 milimeter) residual VSD can be treated conservatively in haemodynamically stable patients (JPMA 60:253; 2010). Introduction Tetrology of Fallot is the most common cyanotic congenital heart defect.1 The mortality rates for untreated TOF are progressive with patients age. With surgery (palliative shunts and corrective surgery) prognosis has improved. Total correction is performed by open heart surgery. Mortality is 3% in children and 2.5% to 8.5% in adults.2 For closure of VSD transatrial and transventricular approaches can be used.3-5 Conventionally, Ventricular Septal Defects (VSDs) are repaired with synthetic patch-Dacron (polyethylene terephthalate) or Goretex (expanded polytetrafluoroethylene).Nonabsorbable continuous or interrupted stitches can be used to close the VSD.3 Surgical correction of TOF can be carried out as early as the first year of life with low morbidity and mortality.6-10 In recent years there has been a considerable increase in adult patients with congenital heart disease.7 Although grown up children can cope well with complicated intra-cardiac repair procedure, total correction in older children and young adults is very challenging. The massive right ventricular hypertrophy completely obscures the morphology of defects hence making the exposure of VSD technically difficult. Therefore in majority of these patients, satisfactory repair through right atrium alone is a procedure requiring high expertise and frequently right ventriculotomy has to be undertaken.3,5,8 Amongst the myriad complications occurring after TC for TOF, residual VSD shares a percentage of 1% to 8% with catastrophic short and long-term consequences.9 The techniques of VSD closure in TOF varies among different surgeons. Although remarkable results have been achieved in the western world, by employing continuous suturing technique for VSD closure in TOF, but the children operated upon are younger, within the first five years of life. In contrast to this a majority of our patients appear late for total correction usually in the second decade of life, as they are referred late. Hence their myocardium differs in architecture from those presenting early as well as the normal heart. The myocardium is hypertrophied, less resilient and friable.10-13 This along with a high RV pressure at a late age, renders the myocardium more likely to give way after suturing. This study was undertaken to compare the results of Interrupted versus Continuous suture techniques for VSD closure with regards to residual VSD after total correction for Tetrology of Fallot in our patient population. Patients and Methods A randomized comparative study was conducted on patients with Tetralogy of Fallot undergoing Total Closure (TC) of VSD between January and December, 2008. The objective was to observe the frequency of failures as residual VSD. The study was approved by the Ethical Review Board of the institution. An informed consent was sought from all patients included in the study. Patients were subjected to transthoracic echocardiography for the diagnosis of TOF and to delineate the main central pulmonary vasculature. All TOF patients with hypoplastic main pulmonary artery and normal right and left pulmonary artery were included in the study. Patients excluded were those with other associated cardiac abnormalities, with branch pulmonary artery stenosis and left anterior descending coronary artery arising from right coronary artery as a continuation of conus branch. All Total Corrections were done under general anaesthesia with continuous invasive monitoring of ECG, arterial pressure, central venous pressure and oxygen saturation. Median sternotomy incision was made to reach pericardium. During pericardiotomy, the pericardial patch was harvested. Forty-seven patients had right S/P shunt which was functioning in 34 patients and non-functioning in remaining 13 patients. Functioning shunt was ligated before undertaking cardiopulmonary bypass (CPB). All patients were put on CPB by aortic and bicaval venous cannulation. Moderate systemic hypothermia (core body temperature between 28-30 degree centrigrade) along with topical cooling was applied. Cold antegrade blood cardioplegia was given after aortic cross clamping. VSD was approached through the right ventricle in 54 patients. However right atrial approach was used in 6 patients under nine years of age as they had less right ventricular hypertrophy compared to the others. A synthetic patch (Dacron) was used to close the VSD in all patients. In 30 (50%) patients VSD was closed with continuous 5/0 proline double ended suture. In remaining 30 (50%) patients VSD was closed with interrupted 5/o prolene double ended sutures. Infundibular muscular resection was performed in 58 patients. This was not necessitated in two patients both of whom fell under 10 years of age with minimal RV hypertrophy. In 44 patients right ventricular outflow tract (RVOT) was enlarged using transannular patch technique. Intraoperati e transesophageal echocardiography (TEE) was not used as the facility was not available at our institute. All patients were nursed in the intensive care unit postoperatively and all were routinely subjected to transthoracic echocardiography on 2nd postoperative day, as majority of the patients depict stability by this period. However, two patients needed transthoracic echocardiography (TTE) earlier because of intractable instability. Data analysis was performed through SPSS version - 10 on computer. Qualitative data including sex, NYHA functional class, risk factors, drug history, ECG finding, x-ray finding, echocardiographic findings (pulmonary valve, VSD 254 J Pak Med Assoc and ASD) were presented by frequency and percentage; chisquare test was applied to compare the proportions of these variables at p 1.5).9,25 Four patients in our study were reopened due to excessive bleeding. For patients presenting with residual VSD or right ventricular outflow tract obstruction (RVOTO) after correction of TOF, reoperation should be considered if progressive right ventricular failure and clinical deterioration develop. Residual VSDs are poorly tolerated in patients with TOF because these individuals cannot tolerate an acutely imposed volume overload. A residual VSD with a 2:1 shunt or an RVOTO of greater than 60 mm Hg is an urgent indication for reoperation. Surgery can be performed with low risk and can result in improvement. Patients with small(less than 05 mm size) residual VSD who are haemodynamically stable can be treated conservatively.9 One patient in our study from continuous technique of VSD closure group, required reoperation for residual VSD while the remaining 4 patients settled without redo surgery. Active prosthetic patch infection is a rare, but serious condition which may require the replacement of the patch. Abscess formation may occur at the tricuspid annulus involving the septal patch, and the leaflet and/or annulus may require reconstruction using an autologous pericardial patch. One patient from our study of the group with continuous suturing technique for closure of VSD, developed infective endocarditis. He responded to conservative therapy with antibiotics. Conclusion Residual VSD is common with continuous suturing repair technique as compared to interrupted suturing technique of VSD closure. This is perhaps because of poor myocardium quality and higher RV pressures in our late presenting patients compared to Western population of patients. Small(less than 05 mm size) residual VSD can be treated conservatively if haemodynamically stable. References 1. Brickner ME, Hillis LD, Lange RA, Brickner ME. Congenital heart disease inadults. Second of two parts. N Engl J Med 2000; 342: 334-42. 2. Presbitero P, Prever SB, Contrafatto I, Morea M. 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