Suruchi Hasija

Prophylactic Vasopressin in Patients Receiving the Angiotensin-Converting Enzyme Inhibitor Ramipril Undergoing Coronary Artery Bypass Graft Surgery

OBJECTIVE The purpose of this study was to compare the effects of continuation versus discontinuation of the angiotensin-converting enzyme (ACE) inhibitor ramipril and assess the efficacy of prophylactic vasopressin infusion on hemodynamic stability and vasoactive drug requirements in patients undergoing coronary artery bypass graft (CABG) surgery. DESIGN A prospective, randomized, double-blinded, single-center clinical study. SETTING Tertiary care hospital. PARTICIPANTS Forty-seven patients on the ACE inhibitor ramipril for 6 weeks before undergoing elective primary CABG surgery on cardiopulmonary bypass (CPB). INTERVENTIONS Patients were randomly divided into 3 groups: group A (n = 16), patients discontinued ramipril 24 hours before surgery; group B (n = 16), patients continued ramipril until the morning of surgery; and group C (n = 15), patients continued ramipril until the morning of surgery and received vasopressin infusion (0.03 U/min) from the onset of rewarming until the hemodynamics were stable without vasopressor agents. The anesthetic technique and conduct of CPB were standardized for all the groups. Hemodynamic parameters and vasoactive drug requirements were recorded for 3 days postoperatively. MEASUREMENTS AND MAIN RESULTS Patients in group A maintained stable mean arterial pressure (MAP) and systemic vascular resistance (SVR). In group B, MAP and SVR decreased after the induction of anesthesia and remained so throughout surgery (p < 0.05). In group C, MAP and SVR decreased upon the induction of anesthesia (p < 0.05) but normalized after CPB. CONCLUSIONS Preoperative ACE inhibitor continuation predisposed to hypotension upon the induction of anesthesia and in the post-CPB period. Prophylactic low-dose vasopressin infusion prevented post-CPB hypotension. Low-dose vasopressin can be considered as potential therapy in these patients.

Evaluation and Comparison of Early Hemodynamic Changes After Elective Mitral Valve Replacement in Patients With Severe and Mild Pulmonary Arterial Hypertension

OBJECTIVE To evaluate and compare early hemodynamic changes after elective mitral valve replacement (MVR) in patients with severe and mild pulmonary arterial hypertension (PAH). DESIGN A prospective observational study. SETTING University-affiliated hospital. PARTICIPANTS Sixty patients undergoing elective MVR. INTERVENTIONS The patients were divided into 2 equal groups based on the presence (group A) or absence (group B) of severe PAH defined as systolic pulmonary artery pressure (PAP) > or = 50 mmHg on preinduction pulmonary artery catheterization. Thiopental, fentanyl, midazolam, isoflurane, and rocuronium (or vecuronium if the heart rate >100 beats/min) were used for the induction and maintenance of anesthesia. MVR was performed using standard cardiopulmonary bypass (CPB) techniques. The therapy for PAH was electively instituted in all patients with a nitroglycerin infusion (0.5-1 microg/kg/min), deliberate hypocarbia (arterial carbon dioxide tension < or = 35 mmHg), fractional inspired oxygen concentration = 1.0, and elective ventilation for at least 12 hours in the postoperative period. Hemodynamic and arterial blood gas parameters were serially measured before induction; after intubation; after termination of CPB; after extubation; and at 6, 24, and 48 hours after surgery. Differences in these parameters were analyzed within and among the groups using appropriate statistical tests. MEASUREMENTS AND MAIN RESULTS The mean CPB and aortic cross-clamp times were similar in the 2 groups (78 +/- 33 and 50 +/- 21 minutes in group A and 63 +/- 32 and 41 +/- 23 minutes in group B). The mean PAP, pulmonary capillary wedge pressure, and pulmonary vascular resistance decreased significantly soon after CPB in both groups (p < 0.001), but the decrease was significantly lower in group A (p < 0.001). The mean PAP approached near-normal values in group A (23 +/- 8 mmHg) and normal values in group B (16 +/- 6 mmHg) immediately postoperatively. There was an increase in cardiac index (p < 0.01) after CPB in group A. A relative improvement in oxygenation occurred after MVR in group A compared with group B (p < 0.001). Patients in group A were ventilated for a longer duration (25.9 +/- 18.8 v 17.3 +/- 7.9 hours, p < 0.05). There was no significant difference in the inotropic requirement between the 2 groups. There was no mortality in either group. CONCLUSIONS PAP returns to near-normal values in patients with severe preoperative PAH and to normal values in patients with mild preoperative PAH immediately after MVR. The outcome after surgery in patients with severe PAH is comparable to those with mild PAH.

Coagulopathies in cyanotic cardiac patients: An analysis with three point - of - care testing devices (Thromboelastography, rotational thromboelastometry, and sonoclot analyzer)

Introduction: In the last few years, viscoelastic point-of-care (POC) coagulation devices such as thromboelastography (TEG), rotational thromboelastometry (ROTEM), and Sonoclot (SON) analyzer have been increasingly used in major surgeries for timely assessment and management of coagulopathies. The aim of the present study was to evaluate coagulation profile of cyanotic cardiac patients with TEG, ROTEM, and SON analyzer. In addition, we assessed the correlation of standard laboratory coagulation tests and postoperative chest drain output (CDO) with the parameters of POC testing devices. Materials and Methods: Thirty-five patients of either gender, belonging to the American Society of Anesthesiologists Grade I–III, and undergoing elective cardiac surgery on cardiopulmonary bypass for cyanotic congenital heart disease were included in this study. To identify possible coagulation abnormalities, blood samples for TEG, ROTEM, SON, and standard laboratory coagulation were collected after induction of anesthesia. The correlations between variables were assessed using Pearsons correlation coefficient. P < 0.05 was considered statistically significant. Results and Discussion: EXTEM clot time (CT) and clot formation time (CFT) were prolonged in 87% and 45% patients whereas INTEM CT and CFT were prolonged in 36% and 73% patients, respectively. FIBTEM maximum clot firmness (MCF) was decreased in 30% patients. We observed significant correlation between fibrinogen concentration and ROTEM FIBTEM MCF (r = 0.94, P < 0.001). The SON platelet function (SON PF) showed good correlation with platelet count (r = 0.85, P < 0.001). We also found significant correlation between preoperative FIBTEM MCF and CDO in first 4 postoperative hours (r = 0.49, P = 0.004) and 24 postoperative hours (r = 0.52, P = 0.005). Receiver operating characteristic analysis demonstrated that SON PF and TEG maximum amplitude are highly predictive of thrombocytopenia below 100 × 109/L (area under the curve [AUC] - 0.97 and 0.92, respectively), while FIBTEM-MCF is highly predictive of hypofibrinogenemia (fibrinogen <150 mg/dL (AUC, 0.99). Conclusion: Cyanotic cardiac patients have preoperative coagulation abnormalities in ROTEM, TEG, and SON parameters. ROTEM FIBTEM is highly predictive of hypofibrinogenemia while SON PF is highly predictive of thrombocytopenia. ROTEM FIBTEM can be studied as a marker of increased postoperative CDO.

Extra cardiac Fontan without cardiopulmonary bypass: techniques and early results

Extracardiac Fontan is currently the preferred final palliation for patients with a univentricular heart. The operation is commonly performed on Cardiopulmonary bypass on a beating heart. In this review, we discuss a protocol for successfully performing this operation without cardiopulmonary bypass. The advantages and pitfalls of this technique are briefly discussed.

Paediatric myocardial protection-strategies, controversies and recent developments

During the last two decades, there has been a phenomenal rise in the number of patients undergoing early primary repair for congenital heart defects. Repair of these intracardiac defects usually requires open heart surgery that necessitates cardiopulmonary bypass, aortic cross clamping and administered cardiac arrest. To achieve this goal, cardioplegia is administered at predetermined intervals to ensure a quiescent heart and protection of the myocardium from ischaemia at the same time. Cardioplegia administration is usually done in conjunction with hypothermia to decrease the metabolic demands of the arrested heart as hypothermia alone is inferior to the combination of hypothermia and cardioplegia in providing adequate myocardial protection. The types and methods of cardioplegia in use today are as diverse as individual surgeons; and most institutions have over time developed their own preferred myocardial protection techniques that have proven to be safe and effective. Most of the available literature and concepts in pediatric myocardial protection today have been borrowed from observations in adults and ex- vivo and in-vivo animal models. The extrapolation of these concepts to pediatric myocardium is inappropriate as immature myocardium is not simply a “small adult heart”. It has unique differences and susceptibilities. This review provides a synopsis of pediatric myocardial protection including types, mechanisms, composition and comparative features of pediatric cardioplegia solutions currently in use all over the world. As of now, there is no evidence favoring one technique or strategy over the other. Pediatric myocardial protection protocols in general are currently experience based.

Randomized Study Comparing Pre-Operative Glycemic Profile in Pediatric Cardiac Surgical Patients Administered Oral Carbohydrate Solution Preoperatively versus Those Kept Fasting

Objectives: Hypoglycemia is a recognized danger in pediatric patients. Extended period of preoperative fasting in this subset of patients is not well tolerated with metabolic derangements. The oral carbohydrate loading preoperatively can ameliorate many adverse effects. The aim of this study was to compare the glycemic profile in pediatric cardiac surgical patients kept fasting preoperatively with those fed oral clear solutions of carbohydrate half hour prior to induction of anaesthesia. Also we tried to establish a correlation with other factors contributing to preoperative hypoglycemia. Methodology: We planned a randomized controlled study. Group A included patients who were kept fasting according to the ASA guidelines preoperatively and Group B included patients who received 2 ml per kg of body weight of 10% Dextrose water as oral feeds half hour before the expected time of start of anaesthesia. Results: The mean (SD) preoperative BG concentrations were higher in group B (102.5 ±16.97) as compared to group A (64.08 ± 25.37) (p value -0.86 and -0.67) (pvalue Conclusion: Preoperative oral carbohydrate preloading can develop as the easiest and cheapest path to better perioperative blood glucose concentration management in congenital cardiac disease children.

Successful Use of Intra-aortic Balloon Counterpulsation for Systemic Ventricular Failure Following Total Pericardiectomy for Calcific Chronic Constrictive Pericarditis

We report two male patients aged 18 and 19 years, respectively, undergoing total pericardiectomy for chronic calcific constrictive pericarditis who developed systemic ventricular failure unresponsive to medical management following surgery. The failing circulation was successfully reestablished using intra-aortic balloon counterpulsation. Aortic counterpulsation facilitates recovery of ventricular function and appears to be a reasonable alternative in select instances of refractory cardiac failure following pericardiectomy.

Randomized Controlled Trial of Heparin Versus Bivalirudin Anticoagulation in Acyanotic Children Undergoing Open Heart Surgery

OBJECTIVE To determine the safety and efficacy of bivalirudin as an anticoagulant for pediatric open heart surgery (OHS) and to determine its appropriate dosage for this purpose. DESIGN Prospective, randomized controlled trial. SETTING Tertiary care hospital. PARTICIPANTS Fifty acyanotic children aged 1-12 years undergoing OHS. INTERVENTIONS The children were randomized to receive either 4 mg/kg of heparin (n = 25, group H) or 1 mg/kg of bivalirudin bolus followed by 2.5 mg/kg/h infusion (n = 25, group B) as the anticoagulant. The doses were adjusted to maintain activated clotting time (ACT) above 480 seconds. At the conclusion of surgery, protamine (1.3 mg/100 U of heparin) was administered to children in group H. MEASUREMENTS AND MAIN RESULTS The children were comparable in both groups with regard to demographic characteristics. The mean age and weight were 51.5 months and 13.4 kg in group H, and 59.3 months and 13.4 kg in group B. The dose of anticoagulant required was 4.0 ± 0.2 mg/kg in group H and 1.7 ± 0.2 mg/kg followed by 3.0 ± 0.7 mg/kg/h infusion in group B (p < 0.001). One child in group H required an additional dose compared to 13 (54.2%) children in group B. Intraoperatively, the ACT achieved was higher in group H compared to group B (p < 0.05). The ACT returned to baseline value after protamine administration in group H, but it remained elevated for 2 hours after termination of cardiopulmonary bypass (CPB) in group B (p < 0.01). The ACT was higher in group B compared to group H for 6 hours after termination of CPB (p < 0.05). Heparin prolonged the onset of clotting, decreased the rate and strength of thrombus formation, and inhibited platelet function to a greater extent than bivalirudin on viscoelastic coagulation testing. The total duration of surgery was prolonged in group B. The postoperative chest tube drainage was similar in group B (4.9 mL/kg) as in group H (5.9 mL/kg) in spite of higher ACT. The transfusion requirements were similar. No adverse event occurred in any patient. CONCLUSION Bivalirudin is a safe and effective anticoagulant for pediatric OHS. Though it is not suitable as a routine anticoagulant for this purpose, it may be used as a heparin alternative in instances when heparin cannot be used. The dose required to maintain ACT for more than 480 seconds was 1.7 ± 0.2 mg/kg followed by 3.0 ± 0.7 mg/kg/h infusion. The ACT remained elevated for 2 hours after stopping the infusion. Bivalirudin did not increase postoperative bleeding and transfusion requirement.

A Comparative Study of Histopathological Changes in the Ascending Aorta and the Risk Factors Related to Histopathological Conditions and Aortic Dilatation in Patients with Tetralogy of Fallot and a Functionally Univentricular Heart

BACKGROUND The purposes of this study were to prospectively evaluate the histologic characteristics of the aortic wall of patients undergoing univentricular type of repair and compare the same with the findings observed in patients undergoing intracardiac repair of tetralogy of Fallot (TOF). PATIENTS AND METHODS Operatively excised full-thickness aortic wall tissue from 99 consecutive patients undergoing either intracardiac repair of TOF (group I; n=42) or univentricular repair (group II; n=57) were studied by light microscopy. Age at operation was 13 months to 28 years (mean 99.97±73.21months) for group I and 9 months to 25 years (mean 79.52±60.09) months for group II patients. RESULTS Dilatation of the ascending aorta was present in 85.7% patients with TOF and 91.2% patients with a univentricular heart. Seventeen (17.2%) aortic specimens were histologically normal and were used as normal controls (group I, n=5; group II, n=12). A lamellar count of less than 60 was associated with a sensitivity of 97.2% and a specificity of 66.7% in patients undergoing repair of TOF and a sensitivity of 84.6% and a specificity of 80% in patients undergoing univentricular type of repairs respectively. Patients undergoing intracardiac repair of TOF and those undergoing univentricular repair exhibited 23.67 times (15.91-147.40) and 8.48 times (3.62-15.84) increased risk of aortic dilatation respectively. CONCLUSIONS Our findings indicate the existence of significant elastic fragmentation, muscle disarray, medionecrosis and fibrosis involving the ascending aortic media in patients with a functionally univentricular heart and dilated aorta. These histopathological changes are similar to those encountered in patients with TOF and dilated aorta.

Effect of heparin and Bivalirudin on the kinetics of clot formation: Viscoelastic coagulation testing

INTRODUCTION Heparin is a widely used anticoagulant that inhibits thrombin and factor Xa via antithrombin III. Bivalirudin is a direct thrombin inhibitor and does not inhibit factor Xa. It inhibits both circulating and clot-bound thrombin. In order to better understand the mechanisms of action of these anticoagulants, we studied their effects on the viscoelastic coagulation tests: Rotational thromboelastometry, Thromboelastography and Sonoclot.Here, we provide only representative signatures obtained on viscoelastic coagulation testing of blood samples of patients undergoing open heart surgery and anticoagulated with either heparin or bivalirudin.