Longitudinal Assessment of Neurocognitive Function after Cardio Pulmonary Bypass

Mohan, R (2007) Longitudinal Assessment of Neurocognitive Function after Cardio Pulmonary Bypass. Masters thesis, Madras Medical College, Chennai.


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INTRODUCTION: In 1954, Lillehei first reported the effective use of Extracorporeal circulation in the repair of CHD using cross circulation with the patient's parent functioning as the oxygenator. Gibbon first described and used a mechanical extracorporeal oxygenator, which he termed the Heart-Lung machine. On May 6, 1953, Gibbon performed the first successful Open heart surgery using a Heart-Lung machine while repairing an Atrial Septal defect. Increasingly complex repairs subsequently became possible with the refinement of Cardiopulmonary bypass (CPB) techniques and the use of hypothermic circulatory arrest that Barratt-Boyes et al (1971) and Castaneda et al (1974) popularized. Further refinements in CPB hardware and techniques, perfusion methods, myocardial and Brain protection over the past 2 decades contributed to improved outcomes of surgical treatment of CHD. The use of CPB is associated with significant cerebral morbidity. The two main clinical manifestations of Brain injury after CPB are Stroke and Cognitive decline. Cognitive decline has increasingly been recognized as a complication after cardiac surgery. Although important advances in techniques for perioperative anesthesia, surgery, and the protection of organs have resulted in substantial reductions in age-adjusted and risk-adjusted mortality, the incidence of cognitive decline has changed little over the past years. The quality of life of patients undergoing cardiac surgical procedures has recently received much attention, especially with respect to the effect of such procedures on cognitive and neuropsychologic outcomes. Elderly patients with multiple health problems, who are at higher risk than other groups of patients for Neurologic and Neurocognitive problems, are now able to undergo surgical procedures relatively late in life without serious concern about loss of life. However, they are at substantially increased risk for Central Nervous System dysfunction and, in particular, Cognitive decline after surgery. The clinical and financial implications of these problems can be profound, since prolonged hospitalization and an increased use of resources are associated with major and even minor Neurobehavioral declines. AIM : This prospective study has been conducted to evaluate various factors associated with Cognitive dysfunction and is aimed at improving the surgical outcome in our patients. The aim of this study Is To perform pre operative Cognitive evaluation and to study the incidence of Cognitive decline after cardiac surgery. 1. To assess the manifestations of Neurocognitive decline after Cardio pulmonary bypass. 2. Comparison between results concerning Cognitive decline in our patients and previous clinical reports and identification of incremental risk factors. 3. To discuss various modalities in improving the surgical outcome. MATERIALS AND METHODS : This study was conducted at The Department of Cardiothoracic Surgery, Madras Medical College and Government General Hospital, Chennai from November 2004 to January 2007. Institutional ethical clearance was obtained for the study. 95 patients who underwent elective open-heart surgery in different units were taken up for the study. Patients who had emergency surgery, who underwent procedures in Deep Hypothermia or Circulatory arrest, who had a History of Stroke, Seizures or previous Psychiatric pathology, Carotid artery disease or Cardiac tumors were not included in the study. Also patients who had less than eighth standard of education or who could not read were excluded. Evaluation was done pre operatively; 7 days post operatively and during the 6t h month of follow up. RESULTS: This study was conducted in 95 eligible patients, 47 of whom were females and 48 males. The mean age of the patients was 30.66 ±12.33 (females 28.35 ±10.18, males 33.5 ±13.95). 6 patients did not turn up for follow up at 6 months. 29 patients underwent surgical correction for Atrial septal defect, 7 patients for Ventricular septal defect, 1 patient had Ventricular septal defect with Aortic regurgitation, 1 patient had Left Atrial myxoma, 30 patients underwent surgery for Mitral valve disease, 9 patients had Aortic valve disease, 4 patients had both Aortic and Mitral valve disease. 14 patients had coronary artery disease and underwent bypass grafting. Saphenous veins formed majority of conduits used with the mean number of grafts being 2.08 ± 0.49. CONCLUSION : Neurocognitive Dysfunction is a frequently occurring complication. The results confirm a High Incidence of Cognitive decline. The incidence in our study was 46.3% in the immediate postoperative period and 13.7% at 6 months. Female patients who constituted 49% of the study group had a Higher Incidence of Anxiety, Depression and Neurocognitive dysfunction. Patients with Lower Ejection Fraction pre operatively had Higher rates of Cognitive decline. This could be due to lower baseline Neurocognitive function in this group of patients. Valvular heart surgeries and Coronary artery bypass grafting were also associated with Higher cognitive decline. These surgeries were associated with Prolonged Cross clamp time and Extracorporeal circulation time. Extracorporeal circulation causing microscopic air embolism and Cerebral and Systemic Inflammatory Activation may be responsible for transient disturbance of Neuronal Metabolism. Microscopic Air embolism could result in Diffuse Cerebral Hypoxemia. However we performed no transcranial Doppler measurements to visualize and confirm the emboli. Lower baseline Neurocognitive function was also associated with Higher rates of Cognitive decline. Pre surgical counseling by Psychologists may probably help in improving the Postoperative Psychological Status.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Longitudinal Assessment ; Neurocognitive Function ; Cardio Pulmonary Bypass.
Subjects: MEDICAL > Cardio Vascular and Thoracic Surgery
Depositing User: Kambaraman B
Date Deposited: 10 Nov 2017 17:00
Last Modified: 10 Nov 2017 17:00
URI: http://repository-tnmgrmu.ac.in/id/eprint/3873

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