Perioperative Myocardial Infarction
Perioperative Myocardial Infarction is diagnosed by the appearance of fresh Q waves. Non-Q, inyocarrlial infarction is suspected when there is serial rise in cardiac cnzymes. Initial reading of cardiac enzymes aftw CAHG on by pass, may show elevation, which settles down if there is no pcri operative MI. With betlcra myocardial protection these days, the incidellcc of peri operative MI which was 5.8 per cent in CASS report has come down Lo 2.5 per cent or even less. The incidence is higher after endartclcctomy. In recent reports, there is no difference in the incidence of pemi operative MI between CABG on pump and off pump(OPCAB).Late follow up shows that 95 per cent of the patients are free of fatal or non-fatal MI five y e a s after CABG. This falls to 85 per cent at 10 years and 65 per cent at 15 years.
Peri Operative Arrhythmias
Cardiac arrhythmias are not uncommon after CABG. These may be ventricular or atrial.
Ventricular Arrhythmias
Perioperative Myocardial Infarction is diagnosed by the appearance of fresh Q waves. Non-Q, inyocarrlial infarction is suspected when there is serial rise in cardiac cnzymes. Initial reading of cardiac enzymes aftw CAHG on by pass, may show elevation, which settles down if there is no pcri operative MI. With betlcra myocardial protection these days, the incidellcc of peri operative MI which was 5.8 per cent in CASS report has come down Lo 2.5 per cent or even less. The incidence is higher after endartclcctomy. In recent reports, there is no difference in the incidence of pemi operative MI between CABG on pump and off pump(OPCAB).Late follow up shows that 95 per cent of the patients are free of fatal or non-fatal MI five y e a s after CABG. This falls to 85 per cent at 10 years and 65 per cent at 15 years.
Peri Operative Arrhythmias
Cardiac arrhythmias are not uncommon after CABG. These may be ventricular or atrial.
Ventricular Arrhythmias
These include premature ventricular contractions (PVC), ventricular tachycardia(VT) and ventricular fibrillation (VT). At times they may be responsible for sudden cardiac death in the post-operative period. So these patients are closely monitored in the first 48 hours. Electrolyte imbalance or ischaernia of the myocardium may trigger ventricular irritability. Coirection of electrolyte and acid base imbalance and judicious use of anti arrhyhnic agents help in the management of ventriculx arrhythmias. Atrial and ventricular pacing wires inserted at the time of surgery help in managing post-operative arrhythmias.
Cardioversion with synchronized shock and defibrillation will be life saving.
Atrial Arrhythmias
Atlial fibrillation is the most common rhythm abnormality after CABG.Paroxysmal atrial tachycardia and atrial flutter are less common. Increased sympathetic stimulation and withdrawal of beta-blockers may be causative factors. The treatment is based on two principles: (1) Rate Control, and (2) Rhythm Control. Rapid intra venous digitalization is seldom used these days.
If haemo dynamics is stable, beta-blockers are used intravenously with caution.Pr~pranolol 0.5 mg LV every two minutes up to a maximum dose of 4mg will help in most cases. Verapa~nil 40mg through naso gastric tube or up to 5mg IV are considered dangerous to treat AF. The currently favoured drug is arniodarone in doses of 5mgIkg given over 20 minutes as an infusion followed by continuous infusion for 4-8 hrs. Oral anliodarone therapy is then continued.
Atrial flutter and paroxysmal atrial tachycardia (PAT) can b e controlled by rapid atrial pacing. Most of the inotropic agents make these arrhythmias worse. It is preferable to give these patients amrinone, which is an inodilator. Beta-blockers and Veraparnil are also helpful. Heart block is treated by pacing through epicardial wires inserted at the time of operation or urgent transvenous temporary pacing.
Diabetes Mellitus Management after Open Heart Surgery
Diabetic patients undergoing coronary artery bypass surgery who are on oral hypoglycemic drugs are pre operatively stabilized with insulin.In the immediate post-operative period, blood sugar levels remain high because of stress and exogenous and endogenous catecholamines. Blood sugar is checked two hourly and controlled with plain insulin intravenously according to a sliding scale. Now it is felt that a strict control of sugar is necessary in the post-o p erative period. The sliding scale is as follows:If the intravenous fluid is 5 per cent dextrose, it is covered with 10 units of insulin/500 ml bottle. On the first post-operative day when the sugars are stabilized, insulin is made subcutaneous 4-6 hourly, using sliding scale. Blood sugar should be kept below 160 mg per cent.
Cardioversion with synchronized shock and defibrillation will be life saving.
Atrial Arrhythmias
Atlial fibrillation is the most common rhythm abnormality after CABG.Paroxysmal atrial tachycardia and atrial flutter are less common. Increased sympathetic stimulation and withdrawal of beta-blockers may be causative factors. The treatment is based on two principles: (1) Rate Control, and (2) Rhythm Control. Rapid intra venous digitalization is seldom used these days.
If haemo dynamics is stable, beta-blockers are used intravenously with caution.Pr~pranolol 0.5 mg LV every two minutes up to a maximum dose of 4mg will help in most cases. Verapa~nil 40mg through naso gastric tube or up to 5mg IV are considered dangerous to treat AF. The currently favoured drug is arniodarone in doses of 5mgIkg given over 20 minutes as an infusion followed by continuous infusion for 4-8 hrs. Oral anliodarone therapy is then continued.
Atrial flutter and paroxysmal atrial tachycardia (PAT) can b e controlled by rapid atrial pacing. Most of the inotropic agents make these arrhythmias worse. It is preferable to give these patients amrinone, which is an inodilator. Beta-blockers and Veraparnil are also helpful. Heart block is treated by pacing through epicardial wires inserted at the time of operation or urgent transvenous temporary pacing.
Diabetes Mellitus Management after Open Heart Surgery
Diabetic patients undergoing coronary artery bypass surgery who are on oral hypoglycemic drugs are pre operatively stabilized with insulin.In the immediate post-operative period, blood sugar levels remain high because of stress and exogenous and endogenous catecholamines. Blood sugar is checked two hourly and controlled with plain insulin intravenously according to a sliding scale. Now it is felt that a strict control of sugar is necessary in the post-o p erative period. The sliding scale is as follows:If the intravenous fluid is 5 per cent dextrose, it is covered with 10 units of insulin/500 ml bottle. On the first post-operative day when the sugars are stabilized, insulin is made subcutaneous 4-6 hourly, using sliding scale. Blood sugar should be kept below 160 mg per cent.
Chest Complications
Many of the patients undergoing coronary artery bypass surgery have risk factors for post-operative lung con~plications. These include old age, chronic obstructive pulmonasy disease (COPD) and heavy smoking with reduced pulmonary functions. So it is important to prevent and treat lung colnplications in the early post-operative period.
After CABG, patients are ventilated for a Tew hours or overnight. Paticnts should ]lave stopped smoking from the time of first consultation for ischaemic hea1-t disease. Pu1moniu.y function tests and pre-operative pliysiotlierapy are done in patients who are at risk. All patients are taught deep breathing and coughing by a physiotherapist pre-operatively. While patient is on ventilator, effective suction to clear all secretions, intermittent lnandatory ventilation (IMV) and pcriodic sighs to prevent alveolar collapse help in reducing puln~onary complications. After extubation, if required, intermittent positive pressure ventilation (IPPV) with a mask will rcduce chances or alveolar collapse. Alvcolm collapse lends to intra pullnonary right to lett shunt and fall in PO,. Regular physiotherapy, coughing,deep breathing and nebulisation with bronc60 dilators will be helpful for early recovery. Tf collapse of segments of lung occurs, fibre optic bronchoscopy should be done. Very few patierits might require prolonged ventilation aiter tracheostomy.
Chest and Leg Wound Complications
The patients unde going CABG are usually elderly, obese and ncarly a cluarlcr of them are diabetic. So sonic of them get superficial or deep cliest wound infectio~ls and morc seriously sternal dehiscence. The incidence of stel-nal breakdown is higher if bilaterill internal malnlnaly artesics ale hrtrvcsted for grafting. It is better to avoid wound problenis with meticulous aseptic precautions, careful liaernostasis and accurate closure of wounds in layers.
Diet
Pre-operatively, patients are on low calorie, low fat diet. However in the immediate post-operative period, strict dieting is not advisable. They need good nutrition for proper wound healing. After a month, they should go back to their previously prescribed diet. Smoking is strictly prohibited forever.
Risk Factor Modification
Even after CABG, patients are at risk of progression of native coronary arteiy disease and development of lesions in the conduits. Modification of risk factors by strict dieting and life style change is important. Effort should be made to achieve ideal body mass index (BMI). Tight co~itrol of diabetes and ideal lipid profilepis vely important. Hypertension has to be strictly controlled. Smoking is prohibited permanently.
Anti Platelet Drugs
In the early years of CABG, patients used to be put on aspirin and persantin(Dipylidamole). Persantin is not routinely prescribed now. Aspirin dose can be reduced to 75-100 mglday. Those patients who are intolerant to aspirin are given ticlopidine or clopidogrel.
Anti Lipid Drugs
The current thinking is that it is very important to keep lipid levels low. It helps in preventing atherosclerotic changes in venous grafts and the long-term patency of grafts improves.
Use of Beta-blockers
In some centers, patients are routinely put on beta-blockers after CABG.European coronary artery surgery study showed that only 25 per cent of pftients use beta-bl~ckers after surgery. However there is a recent trend of using them more frequently after CABG .
Many of the patients undergoing coronary artery bypass surgery have risk factors for post-operative lung con~plications. These include old age, chronic obstructive pulmonasy disease (COPD) and heavy smoking with reduced pulmonary functions. So it is important to prevent and treat lung colnplications in the early post-operative period.
After CABG, patients are ventilated for a Tew hours or overnight. Paticnts should ]lave stopped smoking from the time of first consultation for ischaemic hea1-t disease. Pu1moniu.y function tests and pre-operative pliysiotlierapy are done in patients who are at risk. All patients are taught deep breathing and coughing by a physiotherapist pre-operatively. While patient is on ventilator, effective suction to clear all secretions, intermittent lnandatory ventilation (IMV) and pcriodic sighs to prevent alveolar collapse help in reducing puln~onary complications. After extubation, if required, intermittent positive pressure ventilation (IPPV) with a mask will rcduce chances or alveolar collapse. Alvcolm collapse lends to intra pullnonary right to lett shunt and fall in PO,. Regular physiotherapy, coughing,deep breathing and nebulisation with bronc60 dilators will be helpful for early recovery. Tf collapse of segments of lung occurs, fibre optic bronchoscopy should be done. Very few patierits might require prolonged ventilation aiter tracheostomy.
Chest and Leg Wound Complications
The patients unde going CABG are usually elderly, obese and ncarly a cluarlcr of them are diabetic. So sonic of them get superficial or deep cliest wound infectio~ls and morc seriously sternal dehiscence. The incidence of stel-nal breakdown is higher if bilaterill internal malnlnaly artesics ale hrtrvcsted for grafting. It is better to avoid wound problenis with meticulous aseptic precautions, careful liaernostasis and accurate closure of wounds in layers.
Diet
Pre-operatively, patients are on low calorie, low fat diet. However in the immediate post-operative period, strict dieting is not advisable. They need good nutrition for proper wound healing. After a month, they should go back to their previously prescribed diet. Smoking is strictly prohibited forever.
Risk Factor Modification
Even after CABG, patients are at risk of progression of native coronary arteiy disease and development of lesions in the conduits. Modification of risk factors by strict dieting and life style change is important. Effort should be made to achieve ideal body mass index (BMI). Tight co~itrol of diabetes and ideal lipid profilepis vely important. Hypertension has to be strictly controlled. Smoking is prohibited permanently.
Anti Platelet Drugs
In the early years of CABG, patients used to be put on aspirin and persantin(Dipylidamole). Persantin is not routinely prescribed now. Aspirin dose can be reduced to 75-100 mglday. Those patients who are intolerant to aspirin are given ticlopidine or clopidogrel.
Anti Lipid Drugs
The current thinking is that it is very important to keep lipid levels low. It helps in preventing atherosclerotic changes in venous grafts and the long-term patency of grafts improves.
Use of Beta-blockers
In some centers, patients are routinely put on beta-blockers after CABG.European coronary artery surgery study showed that only 25 per cent of pftients use beta-bl~ckers after surgery. However there is a recent trend of using them more frequently after CABG .
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