**4. Prevention of neurological damage in aortic valve surgery**

Identifying patients at high risk of neurological damage is as important as the techniques to prevent it.

**Pre-operative prevention:** achieving adequate metabolic control, especially in hypertensive and diabetic patients, optimizing treatment for each patient (antihypertensive, anti-anginal), hemodynamic stabilisation and prevention of the patient's previous arrhythmias, and attempting to reduce postoperative atrial fibrillation. It is also important to carry out a prophylaxis to minimise perioperative stress through suitable information for the patient on the surgery they are to undergo.

**Intraoperative prevention:** the possibility of embolisation is the main cause of postoperative stroke, especially as regards the ascending aorta's atheromatous plaques, so it is important to conduct a pre- and post-operative transesophageal echocardiography to diagnose these plaques. In this way one can locate and change the cannulation site, location and type of clamping. Another region from which the embolisations come is the left atrial appendage, above all the flap, and the risk of embolisation here may be reduced by ligature of the same. In valve surgery, delicate mobilization of the heart is particularly important as well as adequate purging of the cavities.

CPB may cause injury to the central nervous system in various ways: it is a cause of embolism and a stimulus for the activation of systemic inflammatory response. This is why


medium - Sepsis


infarction)

epilepsy)



(generalized epilepsy)







SYNDROME DIAGNOSTICS MECHANISMS

STROKE Prior epilepsy

neuropathy

lesion

nerve

**4. Prevention of neurological damage in aortic valve surgery** 

Table 1. Major neurological complications in cardiac surgery

encephalopathy Metabolic encephalopathy Encephalopathy for various reasons

Cerebral Haemorrhage

Paraparesis · Spinal cord infarction - Hypotension (border zone)

Recurrent laryngeal

Injury of the phrenic

Identifying patients at high risk of neurological damage is as important as the techniques to

**Pre-operative prevention:** achieving adequate metabolic control, especially in hypertensive and diabetic patients, optimizing treatment for each patient (antihypertensive, anti-anginal), hemodynamic stabilisation and prevention of the patient's previous arrhythmias, and attempting to reduce postoperative atrial fibrillation. It is also important to carry out a prophylaxis to minimise perioperative stress through suitable information for the patient on

**Intraoperative prevention:** the possibility of embolisation is the main cause of postoperative stroke, especially as regards the ascending aorta's atheromatous plaques, so it is important to conduct a pre- and post-operative transesophageal echocardiography to diagnose these plaques. In this way one can locate and change the cannulation site, location and type of clamping. Another region from which the embolisations come is the left atrial appendage, above all the flap, and the risk of embolisation here may be reduced by ligature of the same. In valve surgery, delicate mobilization of the heart is particularly important as well as

CPB may cause injury to the central nervous system in various ways: it is a cause of embolism and a stimulus for the activation of systemic inflammatory response. This is why

Diffuse encephalopathy Anoxo-ischemic

Epilepsy Diffuse encephalopathy

Peripheral neuropathy Brachial plexus

prevent it.

the surgery they are to undergo.

adequate purging of the cavities.

Focal defect Stroke

membrane oxygenators are used, as well as arterial line filters and smaller circuits coated with heparin. These circuits also attempt to maintain the functioning of platelets, preventing the formation of procoagulants, fibrinolysis, reducing bleeding and the need for transfusion. Proper control of temperature is important (avoiding cerebral hyperthermia), metabolic control and correctly maintaining the acid-base status so as not to increase the possibility of neurological effects.

Cerebral hypoperfusion may reduce purging of microemboli, thereby encouraging neighbouring infarcts. This is why hemodynamic stability should be maintained throughout the surgery. Although autoregulation of cerebral blood flow during cardiopulmonary bypass occurs within a wide range of pressures, hypertensive and diabetic patients may require higher average pressures to maintain perfusion (90 mm Hg). Therefore, although the optimal level is not firmly established, one attempts to apply more pressure than usual to reduce neurological damage in high-risk patients.

Non-CPB surgery does not remove medical complications since the inflammatory response is also triggered, though to a lesser degree. This is associated with a relative reduction in the risk of stroke by 50%.

It is important to try to avoid haematomas on the central or peripheral vascular accesses and pressure zones in order to decrease potential injury to the peripheral nervous system.

**Post-operative prevention:** metabolic control should be continued as regards blood glucose and adequate oxygenation, and anticoagulation and antiagregation should be started immediately. Arrhythmias should be avoided as much as possible, especially atrial fibrillation, usually by using beta blockers.

One should continue avoiding zones of compression or of excessive pressure in order to decrease injury to the peripheral nervous system.

It is very important at this stage to control all that has been mentioned above since all of this may prolong the time in intensive care units, possibly leading to polyneuropathy in the critical patient with a pattern of axonal damage that would cause long-term consequences similar to those caused by the side effects of a stroke. It is therefore important to get the patient to sit up as soon as possible.
