**Pharmacologic support of myocardial dysfunction**

Pharmacological treatment of low cardiac output and reduced oxygen delivery to vital organs is often required in the perioperative cardiac surgical setting. Inadequate treatment may lead to multiple organ failure, one of the main causes of prolonged hospital stay, postoperative morbidity and mortality. Optimal use of inotropes and vasopressors is still controversial and needs further large multinational randomized controlled trials.

However, some recommendations can be made:


#### **Mechanical circulatory support**

*The intra-aortic balloon pump (IABP)* is recommended in the case of heart dysfunction with suspected coronary hypoperfusion. It's main mechanism of action is a reduction of afterload and diastolic coronary perfusion pressure. The IABP reduces heart work and myocardial oxygen consumption, favourably modifying the balance of oxygen supply/demand.

*Extra-corporeal membrane oxygenation (ECMO)* is increasingly used for temporary mechanical circulatory support. Advantages of the system include low cost, availability in all cardiac surgical centers and versatile use for cardiac, pulmonary and renal support. ECMO is used as a bridge to recovery, to transplantation, to long-term assist-device and to decision making.

*Ventricular assist devices* are used today as an established option for patients with end-stage heart failure to obtain a level of functionality that results in an acceptable quality of life for the patient.

#### **Cardiac arrhythmias**

#### *Temporary pacing*

Two temporary right atrial and two right ventricular epicardial pacing wire electrodes are usually placed at the conclusion of cardiac surgery. Atrial pacing wires can be used diagnostically to record atrial activity. These recordings, obtained simultaneously with standard limb leads, can distinguish among atrial and junctional arrhythmias and differentiate them from more life-threatening ventricular arrhythmias. (6)

The use of pacing is often required in the per- and postoperative period to increase heart rate. Atrial or AV pacing will nearly always demonstrate superior haemodynamics to ventricular pacing. Reentrant rhytms can be terminated by rapid pacing.

#### *Arrhythmias after cardiac surgery*

The development of cardiac arrhythmias following open-heart surgery is fairly common and related to altered impulse formation and conduction. An understanding of these mechanisms and the electrophysiologic effects of antiarrhythmic drugs provides a rational basis for the treatment of the different rhythm disturbances.

#### *Atrial fibrillation*

Despite various prophylactic measures, atrial fibrillation and flutter occur in about 35 % of all cardiac surgical patients, most commonly on the second and third postoperative day. Etiologic factors include atrial distension, pericardial inflammation, enhanced sympathetic activity, surgical trauma and poor atrial preservation.

To prevent atrial fibrillation, ß-blockers with or without class III ( Sotalol) antiarrhythmic properties, are commonly administered orally in the perioperative phase. Dual site atrial pacing and numerous other medications (amiodarone, magnesium sulphate, triodothyronine, digoxin, steroids, procainamide, verapamil, diltiazem) have all been reported to have some favourable effect on the incidence of atrial fibrillation after cardiac surgery.

Treatment consists of cardioversion in the haemodynamically unstable patient. For the stable patient, rate control and attempts to achieve conversion are usually initiated. Drugs used for rate control include calcium-channel blockers (diltiazem, verapamil), ß-blockers (esmolol, metoprolol), magnesium sufate and digoxin. For conversion to sinus rhythm, magnesium sulphate, IA medications (procainamide, quinidine) , IC (propafenone) or III antiarrhythmics (Ibutilide, Amiodarone) are commonly used. (29,30,31)

#### **Ventilation management**

Pulmonary complications following cardiac surgery are common, even in patients with healthy lungs, and include diminished functional residual capacity (FRC) following general anaesthesia and muscle relaxants, reductions in vital capacity (VC) following median

and diastolic coronary perfusion pressure. The IABP reduces heart work and myocardial

*Extra-corporeal membrane oxygenation (ECMO)* is increasingly used for temporary mechanical circulatory support. Advantages of the system include low cost, availability in all cardiac surgical centers and versatile use for cardiac, pulmonary and renal support. ECMO is used as a bridge to recovery, to transplantation, to long-term assist-device and to decision making. *Ventricular assist devices* are used today as an established option for patients with end-stage heart failure to obtain a level of functionality that results in an acceptable quality of life for

Two temporary right atrial and two right ventricular epicardial pacing wire electrodes are usually placed at the conclusion of cardiac surgery. Atrial pacing wires can be used diagnostically to record atrial activity. These recordings, obtained simultaneously with standard limb leads, can distinguish among atrial and junctional arrhythmias and

The use of pacing is often required in the per- and postoperative period to increase heart rate. Atrial or AV pacing will nearly always demonstrate superior haemodynamics to

The development of cardiac arrhythmias following open-heart surgery is fairly common and related to altered impulse formation and conduction. An understanding of these mechanisms and the electrophysiologic effects of antiarrhythmic drugs provides a rational

Despite various prophylactic measures, atrial fibrillation and flutter occur in about 35 % of all cardiac surgical patients, most commonly on the second and third postoperative day. Etiologic factors include atrial distension, pericardial inflammation, enhanced sympathetic

To prevent atrial fibrillation, ß-blockers with or without class III ( Sotalol) antiarrhythmic properties, are commonly administered orally in the perioperative phase. Dual site atrial pacing and numerous other medications (amiodarone, magnesium sulphate, triodothyronine, digoxin, steroids, procainamide, verapamil, diltiazem) have all been reported to have some

Treatment consists of cardioversion in the haemodynamically unstable patient. For the stable patient, rate control and attempts to achieve conversion are usually initiated. Drugs used for rate control include calcium-channel blockers (diltiazem, verapamil), ß-blockers (esmolol, metoprolol), magnesium sufate and digoxin. For conversion to sinus rhythm, magnesium sulphate, IA medications (procainamide, quinidine) , IC (propafenone) or III

Pulmonary complications following cardiac surgery are common, even in patients with healthy lungs, and include diminished functional residual capacity (FRC) following general anaesthesia and muscle relaxants, reductions in vital capacity (VC) following median

differentiate them from more life-threatening ventricular arrhythmias. (6)

ventricular pacing. Reentrant rhytms can be terminated by rapid pacing.

favourable effect on the incidence of atrial fibrillation after cardiac surgery.

antiarrhythmics (Ibutilide, Amiodarone) are commonly used. (29,30,31)

basis for the treatment of the different rhythm disturbances.

activity, surgical trauma and poor atrial preservation.

oxygen consumption, favourably modifying the balance of oxygen supply/demand.

the patient.

**Cardiac arrhythmias**  *Temporary pacing* 

*Arrhythmias after cardiac surgery* 

*Atrial fibrillation* 

**Ventilation management** 

sternotomy and intrathoracic manipulation, atelactasis, increased intravascular lung water, and increased capillary leakage and extravascular lung water due to the inflammatory response to CPB and surgery. Multiple blood product transfusions and excessive fluid loading may further compromise lung functioning. Acute FRC reduction results in arterial hypoxemia due to ventilation-perfusion mismatch and shunting. In the early postoperative phase, restoration of FRC and maintenance of adequate gas exchange in the face of rising VO2 and VCO2 are the primary goals. This can be achieved by a lung-protective ventilation strategy with adequate levels of PEEP. (32,33,34)

For several decades, the medical care of the cardiac surgical patients in the perioperative setting consisted of high-dose opioid stress-free anaesthesia and prolonged mechanical ventilation in the ICU. In recent years, the concepts of Fast-Track Cardiac Anesthesia, Early Extubation and Short-Stay Intensive Care became the backbone of modern perioperative care. Indeed, several randomized trials have shown the safety of fast-tracking. (35,36,37,38,39)

Alterations in anaesthetic protocols using short-acting sedatives-hypnotics and analgesics, less invasive surgical and perfusion techniques, improved perioperative haemostasis management, fluid restriction, preservation of normothermia and reduction of the inflammatory response were all crucial steps in the development of fast-track cardiac surgery. As the number of elderly people is growing fast and cardiac surgery is now an accepted practice in these older patients, fast-tracking makes it possible to more efficiently use the limited facilities and resources. (40)

The debate regarding the optimal extubation time, the window of opportunity, is still ongoing. (41) There are several studies on outcome after extubation in the operation room, which show that it is feasible with good results.(42, 43) However, the nadir of ventricular function occurs about 4 hours following cardiopulmonary bypass. Also, the first few hours after cardiac surgery are characterized by periods of haemodynamic instability, temperature dysregulation, increased mediastinal blood loss and other homeostatic disturbances. Patients can rapidly deteriorate in this early postoperative phase and we believe that instabilities can be best anticipated and treated in an ICU setting in sedated and ventilated patients. The window of opportunity for extubation is therefore between 2 and 6 hours postoperatively.

Weaning strategies should be protocolized.(44) In table 1 is shown a nurse-driven weaning protocol which includes the criteria for the start of the weaning procedure, adequate breathing criteria and the extubation criteria. Only three steps in this protocol may mandate the consultation of the ward doctor.

After ventilatory weaning, the next step in the postoperative ICU management is the discharge of the patient to a step-down unit. This is usually accomplished within 8 hours after arrival in the ICU. Intensive Care discharge criteria are shown in Table 2.

#### **The postoperative (intensive) care unit**

The advent of Fast-Track Cardiac Anaesthesia and Short-Stay Intensive Care after Cardiac Surgery also started the discussion whether or not these patients should be treated in a conventional ICU setting. Can adequate and safe postoperative care be given to these patients in parallel "special-care units" such as a dedicated Cardiac Recovery Area (CRA). If a hospital has such a highly-equipped special care unit with a competent and qualified ICU doctor on the ward, adequate nurse-patient ratio and immediate access to ICU-OR facilities, then special care may be feasible. Several institutions reported safe and adequate care in these special units. (45,46) However, in the early postoperative phase, the clinical condition of the patient may

Table 1. Weaning protocol


Table 2. ICU Discharge Criteria

Table 1. Weaning protocol

Table 2. ICU Discharge Criteria

deteriorate extremely rapidly. Therefore, continuous adequate monitoring and maximal acute treatment or intervention should always be readily possible for these patients in the early postoperative period. We believe that currently in most hospitals, the ICU setting is the safest and best place to recover from cardiac surgery. In the integrated model, in which all patients are admitted to the ICU, the postoperative management such as nursing-topatient ratio is variable based on patient requirements. The goal is thus a postoperative unit that allows variable levels of monitoring and care based on patient need. In this model, discharge to a step-down unit as soon as possible after extubation and stabilization of vital parameters should be strived after for every single patient.

#### **Postoperative anticoagulation**

After *coronary artery surgery*, antiplatelet therapy has been shown to inhibit platelet deposition on vein grafts and may delay or attenuate the development of fibrointimal hyperplasia and atherosclerosis. Aspirin should therefore be started after CABG surgery and continued indefinitely because of its beneficial effects in patients with native coronary disease. (47)

After tissue *aortic valve surgery*, there is some evidence that short-term anticoagulation may reduce the incidence of thromboembolism. Therefore, anticoagulation is generally recommended for 3 months in younger patients or those with no contraindication for anticoagulation, and is then converted to aspirin. If anticoagulation is not used, aspirin is given. (48,49)

After mechanical aortic valve surgery, all patients should receive anticoagulation indefinitely to achieve an INR of 2.5 – 3.5 for tilting and bileaflet valves.

After mitral tissue valve or mitral ring implantation, anticoagulation should be given for 3 months to achieve an INR of 2.0 – 3.0 and should then be converted to aspirin if the patient is in sinus rhythm. Anticoagulation should be continued indefinitely in patients with atrial fibrillation, an enlarged left atrium (> 50 mm in diameter), or a history of thromboembolism. After mechanical mitral valve insertion, anticoagulation is given to achieve an INR of 2.5 – 3.5. The addition of aspirin is safe and may further reduce the thromboembolic risk. (50,51)

#### **Echocardiography**

During the past few decades, the effect of perioperative transoesophageal echocardiography's (TEE) influence on perioperative cardiac surgical decision making has become increasingly more appreciated. Data from several clinical investigations have consistently implicated an important, clinically significant, and cost-effective role for TEE as a safe and valuable haemodynamic monitor in identifying high-risk patients, in assessing in the determination of the definitive surgical approach, and in providing a timely postcardiopulmonary bypass evaluation of the procedure, thereby allowing for the opportunity to immediately re-intervene or to at least triage patients appropriately. In addition, perioperative TEE has been instrumental in diagnosing cardiac and associated great vessel pathology and in identifying structural abnormalities, aortic disease, intracardiac masses, and pericardial disease. TEE is perhaps most useful for the perioperative evaluation of cardiac valvular disease, especially during surgical procedures involving the mitral valve. In the intra- and early postoperative period of cardiac surgery, an experienced echocardiographer remains an indispensable clinical team member. Increasing numbers of cardiac anaesthesiologists and intensivists are now being trained and certified as perioperative echocardiographers. (52,53,54)

#### **Analgesia and sedation**

An essential element of postoperative care is the provision of adequate analgesia and sedation. In the patient in whom delayed extubation is anticipated, the residual effects of anesthetics and midazolam in combination with a narcotic are generally accepted.

With the trend toward earlier extubation, short-acting narcotics and analgesics are administered during surgery. This requires early postoperative administration of shortacting medications for pain relief and sedation. We prefer to give low dose continuous infusions of morphine in combination with propofol in the ICU. This usually produces adequate sedation and pain relief without respiratory depression and allows for fairly early extubation.
