Introduction

In General hospital like ours, it is not uncommon to find various medically compromised patients seeking surgical procedures. The coronary artery disease patients contribute sizable proportion of such compromised patients. Based on such fact, we are inspired to initiate a study of clinical nature in such patients.^[1] As long as common population does not receive expert cardiovascular surgical management of various diseases, the proportion of such patients seeking non cardiac surgery is likely to remain high. The study of such a kind also provides us best opportunity for clinical assessment during actual anesthetic management. Also we have chance to assess the risk factors based on available data.

Administrating anesthesia to patients with preexisting cardiac disease is an interesting challenge. Most common cause of preoperative morbidity & mortality in cardiac patients is ischemic heart disease. Ischemic heart disease (IHD) is a leading cause of morbidity and mortality in the world and of perioperative complications in cardiac patients.^[2] The number of people with coronary artery disease with or without intervention coming for non-cardiac procedures has also increased. IHD is number one cause of morbidity and mortality all over the world. Care of these patients requires identification of risk factors, preoperative evaluation & optimization, medical therapy, monitoring and choice of appropriate anesthetic technique & drugs.^[2] Patients with coronary artery diseases undergoing non-cardiac surgery are at an increased risk for peri-operative complications such as myocardial ischaemia, MI, cardiac failure, arrhythmias, cardiac arrest and increased morbidity and mortality. These complications are much higher in patients with recent MI or unstable angina who require urgent or emergency cardiac surgery.^{[3,4,5,6,7,8]}

It is true to say that anesthetist is the person who maintains delicate relationship between the two supporting system of ventilation & perfusion, the later being both pulmonary and systemic. By prevention of abnormal PaO₂, PaCO₂ and P_H of arterial blood that the anesthetist’s role can be best understood, because sympathetic Stimulation is likely to result with low pao₂, high paCO₂ low P_H.

Our special aspect is the management of anesthesia in the Cardiac patients, which requires expertise to administer type of anesthesia, local anesthetic drug volume as well as use of inhalation agent & muscle relaxation agent.^[3]

Present study was done with objectives to study common coronary artery disease and their patho physiology, to identify patients at risk through history, physical examination and electrocardiogram, to evaluate the severity of underlying cardiac disease through cardiac testing taking care to minimize expenditure and to perform specialized test only on high risk patients, testing low risk patients increases cost may causes harm by delaying a non-cardiac operation.

Subjects and Methods

In the present study total 60 patients (37 males & 23 females) having Ischemic heart disease were enrolled in three different groups. The study was carried out at P.D.U. Hospital, Rajkot from October 2006 to October 2008. Diagnosis of all the cases was confirmed by the physician. Many patients had associated history of hypertension and diabetes mellitus.

Results

In the present study, total 60 patients underwent non-cardiac surgeries in general anesthesia, regional anesthesia or peripheral nerve block with different anesthetic drugs and techniques at P.D.U. hospital Rajkot from oct.2006 to 2008.

[Table 2] shows that mostly lower limb surgeries were performed under spinal anesthesia while abdominal and surface surgeries were under general anesthesia. Only limb surgeries were performed under block anesthesia. The shortest procedure in group A and group B was 30 minutes while group C had 40 minutes. The longest surgical procedure in group and group B was 145 minutes while the of group C was 180 minutes.

[Table 3] 25%patients of Group A, 15% patients of Group B and 30% patients of Group C were taking digoxin. Most of the patients were talking anti-coagulant, anti-ischemic or anti-hypertensive therapy.

Above [Table 6] suggests that prolong and major surgical procedures are more associated with the cardiac complications and mortality. Both the patients expired during surgery had developed cardiac complications.

Discussion

In the present study various ischemic heart disease patients undergoing different elective and emergency surgical procedure under different anesthetic techniques, during October 2006 to October 2008.

In present study table I patient‘s characteristics suggest that patients of IHD are more common in older age group(60-70 yrs) and are less common in younger age group(< 50 yrs) . Patients who were in the weight group (60-80 kg) constituted 70% of IHD patients. Male preponderance is present in group A, group B and group C patients.

[Table 2] showing operative data suggests that 60% of lower limb surgeries and lower abdominal surgeries were performed under spinal and epidural anesthesia, upper limb surgeries were performed under peripheral nerve blocks while lower abdominal, neuro and surface surgeries were performed under general anesthesia. Most of the surgical procedures were completed in 1 to 1^1/2hr. in group A patients while in group B patients maximum surgical procedures were completed within 1 hr while in group C patients surgical procedures were completed within 2 Hrs. Two studies were conducted in 1997 about cardiac events in non cardiac surgery.

There are various predictors for cardiovascular mortality. Obesity and physical activity are important predictors of cardio vascular mortality. There are various predictors published regarding to investigate whether cardiovascular mortality related to obesity could be modified by physical activity. In middle age, obesity was associated with increased risk of cardiovascular death but the association weakened with age. After 70, there was no association between BMI and cardiovascular death. At alt ages, a lower level of physical activity was associated with a higher cardiovascular mortality.^[9]

Vatten, lars et al described in European journal of cardiovascular prevention rehabilitation on adiposity and physical activity as predictors of cardiovascular mortality. As women are highly active compensate for obesity than in men so risk was higher in man.^[10]

Patients with significant ischemic changes in ECG were advised to go for 2D echo-cardiography. In Patients treated with diuretics and digitalis, preoperative electrolyte levels were estimated. About 60-70 % patients were taking antiplatelet drugs such as aspirin and clopidogrel.

[Table 3] shows distribution of patients according to nature of pretreatment drugs. Patients with optimized cardio vascular status per operatively by pharmacological treatment have minimal intra operative and post operative complications. Feringa et al has conducted study on Patients with left ventricular dysfunction who are undergoing major non-cardiac vascular surgery are at increased risk of adverse postoperative events. They concluded that the perioperative use of ACE inhibitors, beta-blockers, statins, and aspirin is independently associated with a reduced incidence of in- hospital mortality in patients with left ventricular dysfunction who are undergoing major noncardiac vascular surgery.^[11] Karthikeyan G Bhargava B has explained managing patients undergoing noncardiac surgery need to shift emphasis from risk stratification to risk modification.^[12]

[Table 4] shows distributions of three groups according to Goldman multifactorial index of cardiac risk classification and the incidence of post-operative complications.

According to criteria’s stated in Goldman cardiac risk index, 27 patients were more than age of 70 years and 32 patients had past H/O MI. 5 patient had other than sinus rhythm and >5 VPC per min. 1 patient had s.pottasium less than 3 meq/L and 1 patient had shown signs of chronic liver disease.

[Table 5] shows distribution of three groups according to revised cardiac risk index. As stated in RCRI criteria 32 patients had h/o MI, 27 had h/o angina, 10 had Q wave in ECG while 34 patients were taking nitrates. 22 patients had symptoms s/o CCF and 20 patients had cardiomegaly in chest X-ray PA view. 2 patients had h/o stroke and one had TIA. 3 patients had raised S.creatinine level while 15 patients had been operated for abdominal surgery.^[13]

[Table 6] shows distribution of patients according to surgical risk index. As stated in this risk index patients who were operated for high risk surgeries like emergency surgeries (n= 14), peripheral vascular surgeries (n=6), prolonged surgical procedures associated with large fluid shift and blood loss (n=5) had been associated with intraoperative cardiac complications and 2 mortalities. Emergency surgery is a special case for immediate surgery precludes the time needed to fully evaluate and optimize this patient. In these patients cardiac complications are two to five times more likely to occur.

[Table 7] shows distribution of patients according to ASA physical status grading where majority of the patients were in class III (50%) while 40% were in class IV having two mortalities. Although ASA classification was most commonly used There are some important factors not taken in to account are Age> 75 years, complexity of operation, duration of operation and whether disease is incidental or factorial in current iIIness.^[14]

[Table 8] shows distribution of patients according to NYHA classification where 28 patients fall under class III and 12 in class IV. Patients of both the classes had some intra & post-operative complications with 2 deaths of class IV patients. Thus preoperative cardiac risk assessment is not completed by using single cardiac risk classification. Rather then it must be a multifactorial risk assessment which can actually estimate the cardiac risk associated with non-cardiac surgery in IHD patients. Kareic AA and Rizvon MK have described perioperative cardiovascular escalation. This article covers steps in assessing cardiovascular risk in candidates for non-cardiac surgery, including consideration of patient specific and surgery specific factors.

Effect of G/A, S/A, E/A peripheral nerve blocks on intraoperative and postoperative ECG. Landsberg et al described during the last 20 years, studies using continuous perioperative electrocardiogram (ECG) monitoring in patients at high risk for postoperative cardiac complications have revolutionized our understanding of the pathophysiology, circumstances, timing and possible prevention of perioperative ischemia and postoperative morbidity and mortality.^[15]

Inj. Glycopyrollate (0.04mg/kg) was given to all the patients. As the atria of heart are richly innervated by parasympathetic vagal nerve fibers and the SA node is therefore sensitive to muscarinic receptor blockade. It produces moderate tachycardia and it has little effect on blood pressure. Inj. Ranitidine (1.0mg/kg) and Inj. Ondansetron (0.08, 0.1mg/kg) were given to prevent intraoperative and postoperative vomiting and acidity that might be associated with haemodynamic changes such as rise in blood pressure and tachycardia. All patients were induced with Inj.sodium Pentothal and inj. succinyl choline. In patients who were hypovolaemic or had severe cardiac dysfunction, a precipitous and uncompensated fall in cardiac output had occurred after even a small dose of thiopental. Simultaneous injection of Inj.lignocaine was given to provide haemodynamic stability during laryngoscopy. it can attenuate heart rate, blood pressure, pressure product and pressure rate quotient. In some patients, I had used glyceryl nitrate patch (5 mg) on left side of precordium.

N₂O was used for maintenance as it is good analgesic. Vecuronium was chosen as muscle relaxant which was essentially devoid of cardiovascular effects and so more cardio stable. Atracurium is also highly cardio stable but rarely causes hypotension. Reversal of muscle paralysis with standard agents did not appear to have any detrimental effects in patients with CAD.

In the present study induction of general anesthesia lowers systemic BP by 20-30 o/o. Tracheal intubation increases the blood pressure by 20-30 mm Hg with tachycardia and agent such as nitrous oxide lowers cardiac output of 15%. Additionally inhalational, intravenous anesthetics along with muscle relaxants can be detrimental by sensitizing the myocardium to circulating catecholamine. There may be increased risk of ventricular ectopy. D. Micholoudis and A petrou et al described continuous spinal anesthesia/ analgesia for perioperative management of high risk patients. The intraoperative effect of continuous spinal anesthesia observed in abdominal and orthopedic surgery is reported.^[11]

The total amount of local anesthetic used was 40ml of 1% lignocaine and 20mI of 0.5% of bupivacaine with adrenaline 5mg/ml. postoperatively only one patient was kept in I.C.U. for close observation and monitoring purpose while the remaining patients were sent directly to the wards from the recovery room. There were no complications intraoperatively or postoperatively. The postoperative follow-up of the patients continued for 24-36 hours and the follow-up period was uneventful. By comparing the two anesthetic techniques in the overall population, they found a similar prevalence of patients who had myocardial ischemia and a similar number of ischemic episodes per patient. Episodes of myocardial ischemia were similarly distributed in intraoperative and postoperative periods in both groups. It is relevant that under GA, IHD patients represent most of the population who suffered myocardial ischemia (83%). On the contrary, in the group of patients operated on under LA, the prevalence was equally distributed in the two subpopulations.

Surgeries done under peripheral nerve blocks like under brachial block (50%) and sciatic and femoral nerve blocks (10%) required larger local anesthetic volume compared to other blocks, to decrease the required dose Inj.adrenaline should be added in a proper doses and titrated doses of these drugs should be used. Larger volume may be associated with sedation, myocardial toxicity and myocardial depression. To avoid these side effects, adrenaline had been used be with caution to permit larger doses in combination. intraoperative and postoperative complication in all three group patients. Major complilications encountered were hypotension, hypertension, bradycardia, tachycardia and arrhythmia. 2 patients belong to group C patients had died post operatively.

It was infer that operations managed under peripheral nerve blocks are associated with minimal haemodynamic changes while those operated under regional anesthesia has moderate haemodynamic changes while those operated under general anesthesia also have moderate to severe haemodynamic changes. Weitz H H has done study on perioperative cardiac complications. Although infrequent perioperative cardiac complications are source of major morbidity or mortality, as the population ages, prevalence o (disease increasing.^[16]

Post-operative care is as much important as intra operative management. Fluid management, respiration and haemodynamic stability should be considered post operatively.

Thus preoperative assessment of cardiac risk in patients undergoing non cardiac surgery is a challenge to anesthesiologist. A history, thorough physical examination and judicious use of laboratory investigations will supplemented by the data related to the surgical procedures—type, site etc. suffice to assign the categories to patients as low risk, intermediate risk and high risk for surgery. It is important to combine preoperative assessment of cardiac risk with perioperative cardiac risk reduction strategies and optimization of medical treatment to improve patient’s long-term cardiac outcome. Therapeutic strategies may be different according to situation. PledicaI treatment may be optimized, surgical procedure and anesthetic management may be modified, or risk / benefit ratio of a surgical procedure should be evaluated differently.

Conclusion

By careful understanding of the ischemic heart disease and knowing circulatory variable affecting the ischemic heart disease we can improve anesthetic management of such patients. Through preanesthetic assessment is essential to know the associated risk factors. Pre-operative treatment with anti-ischemic drugs, anti-hypertensive drugs, digoxin, furosamide reduces the incidence of post-operative CCF. Heavy sedation is necessary and atropine should be avoided in premedication. A good anesthetic technique includes adequate analgesia, oxygenation ventilation and normovolemia. Intra operative monitoring of the vital data pulse, blood pressure, respiratory rate in spontaneous respiration and three limb lead E.G.G. help to detect arrhythmia. Patients managed by peripheral nerve blocks and central neuraxiel blockade has better outcome. High standard of post-operative care including pain relief and continuous ECG monitoring is required to reduce the increased morbity and mortality in susceptible patients. Choice of anesthetic technique depends up on type of surgery, duration of surgery and surgical risk factors of patients.