Keywords
anesthetic considerations - cardiac disease - neurosurgery
Introduction
Many neurosurgical procedures and associated pathophysiological states have significant
interactions with the cardiovascular system in most healthy patients. Conversely,
patients with underlying cardiac disease may come across the need to be anesthetized
for neurosurgical procedures, which may be elective or emergency in nature. Several
clinical considerations come into play for this group of patients, in terms of preoperative
assessment and optimization, intraoperative management, and postoperative care. Preservation
of cardiovascular stability is a primary concern, as the central nervous system (CNS)
function depends on the presence of adequate oxygen and substrate for metabolism.
This article attempts to review and discuss several aspects of neuroanesthesia for
a patient with cardiovascular disease. This review is primarily narrative in character,
with most of the recommendations having been referenced to the 2014 new ESC/ESA (European
Society of Cardiology/European Society of Anaesthesiology) guidelines on noncardiac
surgery and the 2014 ACC/AHA (American College of Cardiology/American Heart Association)
guidelines on perioperative cardiovascular evaluation and management of patients undergoing
noncardiac surgery. References have also been made to 2018 ESA guidelines for preoperative
evaluation of adults undergoing elective noncardiac surgery. Apart from these, Ovid,
PubMed, Google Scholar, and Medline were searched with MeSH terms “anesthetic management,”
“noncardiac surgery,” and “neurosurgery,” with a primary focus on review articles
and controlled studies.
Preoperative cardiovascular disturbances are common in patients undergoing neurosurgical
interventions that include, but are not limited to, blood pressure fluctuations, electrocardiographic
abnormalities, arrhythmias, and myocardial ischemia or failure.[1] There are concurrent central neurogenic effects on the heart as well as autonomic
nervous system, as also the effects exerted due to underlying medical conditions.
Preexisting cardiac disease, both symptomatic and asymptomatic, should be identified
and investigated, as much as possible. The decision to perform further diagnostic
evaluations should follow established guidelines, while customizing it as per patient
and surgical indications.[2] The use of appropriate scoring systems is a reliable and fairly standard way to
stratify risk as well as predict outcome. These include the EuroScore, CAREscore,
etc., which, however, are more useful in cardiac patients undergoing cardiac surgery.[3]
[4] These unique issues pose a significant challenge to the anesthetist and therefore
call for a systematic approach to the problem.
One is likely to come across patients in clinical practice with cardiac issues that
may be congenital or acquired, such as hypertension, ischemic heart disease, valvular
heart disease, arrhythmias, and patients with pacemakers or ICD (implantable cardioverter-defibrillator)
in situ. [Table 1] summarizes common cardiac conditions and their relevance to the brain. The more
critical ones may present in a decompensated state of a chronic cardiac illness. Deserving
due attention is the list of many cardiac medications that these patients are often
on and that could have an impact on the perioperative management. The discussion of
management of most of these patients is based on the 2014 revised ACC/AHA recommendations
that provide a useful tool in terms of assessment, risk stratification, and optimization.
Also taken into consideration are the 2014 new ESC/ESA guidelines on noncardiac surgery.[5] The 2018 ESA guidelines on preoperative evaluation of adult patients undergoing
noncardiac surgery also discuss the assessment and optimization of patients with cardiac
disease.[6] These have also been referred to and incorporated into this review.
Table 1
Common cardiac conditions and their effects on the brain
|
Cardiac pathology
|
CNS concerns
|
|
Abbreviation: CNS, central nervous system.
|
|
Hypertension
|
Impaired cerebral microcirculation
|
|
White matter hyperintensities, Alzheimer-like changes, lacunar infarcts
|
|
Risk of aneurysmal rupture
|
|
Risk of subarachnoid hemorrhage, stroke
|
|
Valvular heart disease
|
Arrhythmias and risk of thromboembolism leading to ischemic stroke
|
|
Anticoagulation postvalvular replacement
|
|
Congenital heart disease
|
Risk of stroke and brain abscess
|
|
Developmental delay in children
|
|
Heart failure
|
Impaired cerebral perfusion
|
|
Anticoagulants
|
Risk of hemorrhage/intracranial hematoma
|
Preoperative Assessment and Optimization
Preoperative Assessment and Optimization
Preanesthetic evaluation is a process of clinical assessment, risk stratification,
and optimization before surgery to reduce the perioperative morbidity and mortality.
Most neurosurgical procedures are considered to be moderate to high-risk surgeries.
Apart from these patient-related risk factors, each neurosurgical procedure carries
its inherent risk and requires specific preoperative evaluation and optimization.
Risk stratification not only provides information to both the patient and the neurosurgeon
to understand the benefit versus risk of each neurosurgical procedure but also helps
the perioperative physician optimize the patient before surgery. The essential consideration
in optimization is the urgency of indication. While the terms “emergency” and “urgency”
are commonly used, the guideline writing committee for 2014 ACC/AHA recommendations
further defined two terminologies.[4] A “time-sensitive procedure” defined as one in which a delay of 1 to 6 weeks, to
allow for an evaluation and significant changes in management will negatively affect
outcome, which would include most of so-called elective neurosurgical procedures.
An “elective procedure” was defined as one in which the procedure could be delayed
for up to 1 year, without significant consequences.
As many times as it may have been stated and restated, the significance of a detailed
and structured history cannot be undermined. Combined with a thorough clinical examination,
it is the simplest and the most effective tool in preoperative assessment. Apart from
the duration and severity of the underlying cardiac disease, detailed information
of the concomitant medications and any past medical interventions are also necessary.
Two patients with similar cardiac conditions and planned for similar neurosurgical
procedures may carry different preoperative risk, simply by being differently optimized.
Besides a more accurate risk stratification, this step can also help decide the necessary
investigations, thereby avoiding delays caused by unnecessary laboratory work. It
goes without saying that these aspects may be rushed in case of an emergency, but
none should be omitted or bypassed.
Congenital Heart Disease
As stated above, cardiac issues of significance could be a result of the underlying
neurological condition or an independent entity. The latter, in turn, could either
be a congenital or an acquired condition, both of which bear individual significance.
Children and adults with CHD (congenital heart disease) are at increased risk of mortality
and morbidity when undergoing noncardiac surgery.[7] A point system for the risk stratification of a CHD patient before undergoing a
procedure was developed by Mossad.[8] This classification factors in variables such as complexity and physiology of cardiac
lesion, type and urgency of surgery, age, and the duration of preoperative hospital
stay. A patient presenting for noncardiac surgery may have undergone a corrective
cardiac surgery, may have a residual cardiac lesion after correction, or may have
an uncorrected lesion such as a grown-up with CHD (GUCHD). GUCHD patients represent
a spectrum, from completely well patients with normal physiology to those with severely
deranged physiology.
Cyanotic heart diseases such as tetralogy of Fallot predispose the patient to recurrent
brain abscess as well as cerebral infracts due to underlying polycythemia, and also
complicate the anesthetic management of the same. Fever, coagulopathy, dehydration,
electrolyte imbalance, and metabolic acidosis are areas of concern, and most anesthetists
prefer to have these corrected prior to surgery, where possible. Children surviving
with dTGA (transposition of the great arteries) are also more likely to have abnormal
neurological examinations, learning disabilities, and behavioral disorders, compared
with general population.[9]
[10] Motor and global developmental delay may be seen more commonly in children with
multiple types of CHD, in addition to TGA.[10] More than one-half of newborns with CHD have clinical evidence of neurological abnormalities
on examination even prior to corrective cardiac surgery, and these are a major risk
factor for later neurodevelopmental impairment.[11] Additional factors such as prolonged circulatory arrest or adverse events during
cardiopulmonary bypass may add to the neurological insult.[12]
A thorough evaluation of the patient with CHD should be undertaken before elective
neurosurgery, including an electrocardiogram (ECG), chest X-ray, echocardiography,
and blood tests for full blood count and coagulation screen. When feasible, this should
be performed in a center equipped with experienced surgeons and cardiac anesthesiologists.
This ensures that CHD specialists are involved in close perioperative follow-up, and
this should always be the case when a complex and cyanotic adult patient with CHD
is prepared for neurosurgery.
Anesthetic management is centered around the balance between systemic and pulmonary
vascular resistance, guiding the choice of anesthetic agents for induction and maintenance.
Avoidance of activation of the sympathetic nervous system with consequent catecholamine
release needs to be weighed against the effects of a reduction in systemic vascular
resistance (SVR), which can worsen hypoxia, resulting in hemodynamic collapse. The
cerebral perfusion pressure (CPP) may also be adversely impacted. Reactive pulmonary
hypertension could be challenging to manage in older children or adults with untreated
shunts, which may be worsened by sympathetic stimulation, acidosis, hypercapnia, and
hypothermia. Input and output monitoring become even more significant, given the risk
of heart failure weighed against hypoperfusion, which can aggravate underlying renal
impairment, given the association with extracardiac anomalies of airway, skeletal,
genitourinary, and gastrointestinal systems. Good pain relief and control of nausea-vomiting
along with monitoring for events, such as dysrhythmias, bleeding, and thromboembolic
events, are warranted.
Ischemic Heart Disease and Heart Failure
Active or unstable cardiac conditions, such as unstable angina, acute heart failure,
and symptomatic cardiac arrhythmias, and valvular heart disease or recent myocardial
infarction (MI) (within 6 months) are associated with very poor perioperative outcome.
Heart failure is a major independent predictor of adverse perioperative outcome in
noncardiac surgery and carries a greater perioperative risk than ischemic heart disease.[13] Severely reduced left ventricular ejection fraction (LVEF < 30%) itself is an independent
contributor to perioperative outcome and a long-term risk factor for death in patients
with heart failure undergoing elevated-risk noncardiac surgery.[14] Diastolic dysfunction, with or without systolic dysfunction, also carries a significantly
higher-risk postoperative heart failure.[15] The role of a multidisciplinary team, with the anesthetist, neurosurgeon, cardiologist,
possibly a cardiothoracic surgeon, and an intensivist, is reiterated.
For an elective procedure, the ideal approach would be to treat acute coronary episodes
and optimize heart failure as much as possible. Appropriate medical therapy, if not
already in place, should be initiated as well as titrated. This may include β-blockers,
calcium channel blockers, antiarrhythmic drugs, diuretics, and possible use of ventricular
assist devices. Almost all elective neurosurgical procedures can be delayed till the
stabilization of an acute cardiac event.
Valvular Heart Disease
More challenging could be a situation with a patient with severe valvular heart disease
but not in heart failure. In such cases, the risk of proceeding with a failing valve
versus the benefit of having the valve replacement performed is a difficult decision
to make. Severe valve stenosis can lead to adverse hemodynamic events leading to MI
or heart failure with aortic stenosis (AS) and mitral stenosis (MS), respectively.
Stenotic valvular lesions can be particularly challenging to manage intraoperatively.
Induction in patients with AS should focus on stable hemodynamics while achieving
adequate anesthetic depth, due to the low fixed cardiac output state. All efforts
should be made to maintain normal sinus rhythm to ensure the atrial contribution to
ventricular filing is maintained. Any hypotension can cause reduced coronary as well
as cerebral perfusion pressure and should be rapidly managed with the early use of
boluses of α-adrenergic agonists. Anesthetic management of MS should focus on control
of heart rate, ventricular preload, diminished right ventricular (RV) and left ventricular
(LV) contractile function and coexisting pulmonary hypertension. All measures to avoid
increases in pulmonary arterial (PA) pressures, by avoiding hypoxia, hypercarbia,
acidosis, lung hyperexpansion, and nitrous oxide should be practiced. Patients are
often on anticoagulation, whose management is discussed in detail, later in the text.
In patients ineligible for surgical valve replacements, the options of balloon dilatation
or transcatheter valve replacement (for aortic valve) or valve commissurotomy (for
mitral valve) should be considered. This decision making also should involve all the
specialties, consider the urgency of neurosurgical indication (malignancy, aneurysm),
and include the patient’s opinion as well. The postoperative anticoagulation in valve
replacements only adds to the challenges, with the potential to cause or worsen an
intracranial bleed.
Hypertension
Patients with hypertension are probably the most common to be encountered. In many
cases, newly diagnosed hypertensives are started on treatment, but insufficiently
optimized due to lack of time or started on multiple medications in an attempt to
bring down the “blood pressure within normal limits” urgently. Due consideration must
also be given to the possibility of intracranial pathology as the cause of hypertension.
Many of these patients end up getting either hypotensive due to overtreatment or have
hypertensive surges intraoperatively. These are of particular significance in neuroanesthesia
as blood pressure trends significantly impact CPP and therefore intracranial pressure
(ICP). There is also a marked risk of acute postoperative hypertension, to the tune
of 57% to 91% in patients undergoing intracranial neurosurgery.[16] Rather than blindly target a “normal” number for blood pressure, it is reasonable
to record a baseline and carry out a charting in whatever time is available. This
chart should be used intraoperatively as a guide for blood pressure management, which
will help preserve autoregulation as well as avoid unnecessary chasing of “normal
values.” It has been recommended to cancel elective surgery if the systolic blood
pressure is 180 mm Hg or higher or if the diastolic blood pressure is 110 mm Hg or
higher.[17] A assessment of end-organ damage due to hypertension can be a useful guide to determine
the urgency and need for treatment.
Patients with Status Postcardiac Intervention
This group includes patients having undergone corrective cardiac surgery or interventions
for management of cardiac symptoms. The cardiac functional status for most patients
would have been significantly improved, possibly optimized to the maximum. More relevant
in these patients would be the management of concurrent medical treatment. The concerns
and recommendations for continuation of antihypertensives, β-blockers, etc. have been
discussed later in this text. The more challenging aspect is the management of anticoagulation.
Patients having undergone valve replacement or at high risk of thrombosis would have
been started on warfarin, whereas patients having required revascularization or thrombolytic
therapy may have been started on single or dual antiplatelet therapy. Apart from these,
newer anticoagulants such as rivaroxaban are also being used for long-term anticoagulation.
Continuation of these may increase the risk of surgical bleeding, whereas discontinuation
may exacerbate or complicate the underlying cardiac condition.
The decision to stop this therapy before surgery is controversial, and consultation
with specialists such as the hematologist, cardiologist, and surgeon is useful. Contraindications
to antithrombotic therapy include traumatic brain injury, craniotomy, hemorrhagic
stroke, uncontrolled hypertension, and preexisting coagulopathies and/or advanced
hepatic or renal disease. The urgency of procedure and the indication for starting
the therapy in the first place should be reviewed. Patients on warfarin, especially
for prosthetic valves in situ, are better managed with a bridging therapy to heparin,
which is more titrable.
For patients at high risk of bleeding but also with high thrombotic risk, aspirin
can be continued but all other antiplatelet medications must be withheld (7 days for
clopidogrel and 14 days for ticlopidine), whereas if the thrombotic risk is low and
if the bleeding risk outweighs the potential cardiovascular benefit, aspirin is withheld
for 7 days as well.[18] This is also recommended for patients undergoing spinal surgery or certain neurosurgical
procedures. The decision should, however, be determined by individual assessment of
risk versus benefit.[6] This can be done using several criteria or risk factors for thromboembolism.[19] Rivaroxaban needs to be withheld for at least 48 hours to eliminate its risk of
bleeding, and it is generally restarted 48 to 72 hours postoperatively, thus eliminating
the need for bridging therapy. Patients with coronary stents (bare metal as well as
drug eluting) need individual risk stratification for continuation or stopping of
antiplatelet drugs.[20] The use of vitamin K, fresh frozen plasma, and prothrombin complex concentrate should
be considered as appropriate.
Preoperative Medications
Patients diagnosed with long-term, optimized hypertension should avoid changes in
the regimen, in the immediate preoperative period, if possible, unless essential.
Although ACC/AHA guidelines recommend continuation of angiotensin-converting enzyme
(ACE) inhibitors and angiotensin receptor blockers,[4] it may be reasonable to withhold them on the day of surgery, given the risk of protracted
hypotension, which is far more ominous in neuroanesthesia. Patients on diuretics need
extra caution when being administered osmotic diuretics such as mannitol, and an eye
should be kept on intravascular volume as well as electrolytes. The accompanying diuresis
may result in volume contraction, which increases the risk of hypotension causing
myocardial or cerebral ischemia. These acute changes in intravascular volume may not
be tolerated well by patients with decreased cardiac reserve.
Multiple studies have reported improved outcome in patients receiving perioperative
β-blockers; however, newer studies have reported that perioperative β-blockers may
not be effective if heart rate is not well controlled or in low-risk patients.[21] The recommendations on perioperative β-blockade have been seriously challenged after
the discovery of scientific unreliability in the DECREASE (Dutch Echocardiographic
Cardiac Risk Evaluation Applying Stress Echocardiography) studies that provided much
of the evidence in its support.[22] The evidence in this regard has been critically reanalyzed, and now the only remaining
1B recommendation is that patients currently on this therapy should continue it during
the perioperative period.[6]
In a recent retrospective review of patients for noncardiac surgery, acute surgical
anemia increased the risks of cardiac complications in β-blocked patients, hence suggesting
that higher transfusion triggers should be considered in elective surgical patients
on β-blockers.[23] The current 2014 ACC/AHA guidelines on the perioperative β-blocker administration
advocate that perioperative β-blockade should be used in patients on β-blockers and
those with positive stress test undergoing major vascular surgery.[24] Due consideration should be given to severe bradycardia, in β-blocked patients,
which may occur in cases of herniation. Acute administration of β-blockers without
titration has been concluded to be unfavorable for outcome, whereas statins have been
shown to improve perioperative cardiac outcome, hence are continued in patients currently
taking them.[25]
Very careful risk-benefit analysis is called for, in patients on long-term anticoagulation,
for several conditions, for example, AF, deep vein thrombosis, valve replacement,
or coronary stenting. This has been discussed in detail earlier in the text.
Investigations and Cardiac Testing
Investigations and Cardiac Testing
Preoperative investigations should include cardiac testing (as indicated) as well
as the general investigations. Most patients undergoing neurosurgery will need a hemoglobin
testing and a blood group and cross-match (where transfusion is a possibility). Other
blood investigations should be governed by presence of specific conditions such as
renal function tests in diabetes or long-standing hypertension and electrolytes in
patients on diuretics or mannitol. A resting ECG is desirable in all major procedures.
Preoperative cardiac testing incorporates functional testing as well as investigations.
Functional tests are used to obtain information that may have been missing or insufficient
in history. Functional status is a reliable predictor of perioperative and long-term
cardiac events, and so patients with reduced functional status preoperatively are
at an increased risk of complications. On the other hand, a good functional status
in an asymptomatic patient can rule out the need for several investigations. The most
common method of functional assessment is metabolic equivalents (METs), in which 1
MET is the resting or basal oxygen consumption of a 40-year-old, 70-kg man and is
largely derived from activities of daily living.[26] Perioperative cardiac and long-term risks are increased in patients unable to perform
4 METs of work during daily activities. More formally applied scales such as the DASI
(Duke Activity Status Index) and the Specific Activity Scale can be used to assess
the functional status.[27]
[28] It may be noted here that neurosurgical patients may have a limited functional status
by virtue of underlying pathology as well, and this must be borne in mind during evaluation.
The 2018 ESA guidelines recommend the use of the ACS National Surgical Quality Improvement
Program (NSQIP) index score and the RCRI (Revised Cardiac Risk Index) in conjunction,
for risk stratification of preoperative cardiac risk.[29]
As mentioned above, a resting preoperative 12-lead ECG is required for almost all
major procedures. It is particularly useful as a baseline, to compare with in case
of any new changes in the postoperative period. It is preferable to obtain one within
last 3 months, if the patient is stable. It must be noted that some ECG changes may
be a result of the underlying neurological issue rather than a cardiac one. For example,
a patient with subarachnoid hemorrhage (SAH) may show several rhythm abnormalities
on ECG. ECG abnormalities occur in 50% to 72% of patients with intracranial pathology,
some of which may not appear for 2 weeks after the first insult but are not always
associated with cardiac abnormalities.[30] Most common findings are ST-segment changes, flat or inverted T waves, prominent
U waves, and prolongation of the QTc interval.[31] Therefore, the extent of myocardial ischemia is difficult to assess from ECG alone
in a patient with intracranial pathology.
A preoperative LV function evaluation with echocardiography should be asked for a
patient with undiagnosed dyspnea, or worsening heart failure, or any other change
in clinical status. Postvalvular replacement should also be requested, if more than
1 year has elapsed since the last evaluation.[32] In patients with valvular heart disease, severity of stenosis or regurgitation,
systolic function, and right heart pressures should all be estimated. If time permits,
a stress echo can provide more accurate and reliable information. If further indicated,
nuclear imaging study or coronary angiography may be performed as appropriate.
The measurement of the serum concentrations of brain natriuretic peptide (BNP) or
its inactive precursor N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be
used for risk stratification and prognostication.[33] The assessment of cardiac troponins is recommended in high-risk patients both before
and 48 to 72 hours after surgery.[5] Measurement of biomarkers, especially natriuretic peptides, may be helpful in assessing
and diagnosing patients with heart failure. However, there is no evidence for their
routine use in patients with cardiac disease.
Anesthetic Management
Basic principles of maintaining hemodynamic stability and cerebral protection apply
as for neurosurgical procedures performed in any patient. However, the use of goal-directed
fluid and drug therapies, along with invasive or noninvasive cardiac output monitoring
to improve outcome, has found support in many studies. The delicate balance between
maintaining a relative hypertensive state and preventing hypertensive surges becomes
even more challenging against the background of cardiac disease. On occasion, the
need to maintain a low normal blood pressure, as during arteriovenous malformation
repair, or inducing hypertension to maintain cerebral perfusion during vasospasm,
following SAH, adds to the anesthetic challenges. These hemodynamic changes can have
a profound effect on an already compromised cardiovascular system.
A good, balanced anesthetic technique is crucial for cerebral protection, preserving
CPP, preventing surges in ICP, reducing cerebral metabolic rate of oxygen consumption
(CMRO2), and preventing secondary insults. Furthermore, the anesthetic technique of choice
should maintain or only minimally interfere with cerebral autoregulation and responsiveness
to CO2. It should also be able to maintain relaxation of the brain and provide fast, predictable
recovery for early evaluation of the surgery.
Of particular concern is the delicate management of fluid balance. Patients with cardiac
disease, especially heart failure and valvular heart disease, are at increased risk
of fluid overloading. This should especially be taken care of in emergencies such
as traumatic brain injury or SAH, where an attempt of fluid resuscitation can cause
cardiac compromise. The use of agents such as mannitol and furosemide, used to decrease
ICP, can cause fluid and electrolyte imbalance. Particularly K+ depletion can precipitate arrhythmias in susceptible patients and cause problems
in patients on treatment with digoxin.
Goals during induction of anesthesia are to maintain cerebral and myocardial perfusion
with judicious use of appropriate induction agents. Both propofol and thiopentone
preserve cerebral autoregulation and decrease metabolic requirement of O2 as well as cerebral blood flow.[34] Generous doses of opioids at induction help in preventing exaggerated hemodynamic
responses to airway management. The prophylactic use of vasopressors may be considered
to avoid extreme changes in hemodynamics; the choice of appropriate agent should be
made with the consideration of underlying cardiac condition. This may include the
use of drugs such as dobutamine, noradrenaline, and adrenaline to maintain cardiac
output as well as SVR. Even though mean blood pressure, and therefore CPP, is increased
by all catecholamines, adrenaline has been seen to significantly increase the cerebral
blood flow, compared with noradrenaline and dopamine, in some animal studies.[35] The use of total intravenous anesthesia, with monitoring of the depth of anesthesia,
has become a standard practice in many centers, due to a predictable and consistent
induction as well as maintenance of anesthesia. The use of target-controlled infusion
offers the benefit of use of optimum doses of hypnotic agents with stable hemodynamics.
It has especially become the technique of choice for traumatic brain injury. The choice
of muscle relaxants is dictated by the need for electrophysiological monitoring during
the surgery. Intraoperative electrophysiological monitoring may help prevent postoperative
deficits.
The maintenance of anesthesia can be performed using volatile as well as intravenous
anesthetics. Apart from the neuroanesthetic perspective, the use of either is acceptable
in patients with cardiac disease. The use of total intravenous anesthesia (TIVA) offers
the advantage of more accurate titration of anesthetic agents and hence better control
of hemodynamics. The use of nitrous oxide is better avoided against the background
of pulmonary hypertension and in conjunction with volatile agents when motor-evoked
potentials are being monitored.[36]
Apart from standard monitoring, advanced cardiac monitoring may be considered. As
stated earlier, ECG interpretation can be tricky in these patients due to interplay
of cardiac as well as neurological factors. Common ECG changes include T-wave abnormalities,
Q-T prolongation (which may predispose patients to torsades de pointes and ventricular
fibrillation), ST segment changes, prominent U waves, and various rhythm abnormalities,
such as supraventricular tachyarrhythmias, bradyarrhythmias, and ventricular tachyarrhythmias.[37] These should be treated with β-blockers, calcium channel blockers, and other antiarrhythmic
drugs, as indicated. The mechanism of these changes is understood to be multifactorial,
which include elevated catecholamine levels, hypercortisolism, and hyperkalemia. There
is also a strong association between hypothalamic lesions and myocardial damage.[38]
The use of transesophageal echocardiography (TEE) is especially beneficial in patients
with cardiac disease, as early changes in myocardial function may be detected. Invasive
blood pressure monitoring is recommended in most patients, governed by either the
underlying cardiac condition or the neurosurgical procedure planned. The monitoring
of cardiac output (along with stroke volume, stroke volume variation, and SVR) may
add significant clinical input to the management. Transcranial Doppler, in particular,
is useful to determine whether autoregulation is intact and whether a protocol is
appropriate for maintaining CPP.
Positioning for surgery may also bear implications that are more serious than for
normal patients. Care must be taken of the change in hemodynamics during positioning,
especially sitting up, prone, etc. The sitting position for craniotomy may be required
in certain neurosurgical procedures. Problems associated with this position, however,
limit its use in patients with cardiac disease. It is not uncommon to observe severe
decreases in blood pressure in the sitting position with anesthetized patients. In
patients with coronary artery disease, this could result in myocardial ischemia, whereas
in patients with valvular heart diseases requiring maintenance of high preload, cardiovascular
collapse may occur.[39] Thus, the sitting position may be avoided in these patients, where possible. And
even when used, vigilant monitoring with invasive cardiac output monitoring and TEE
is indicated.
The consideration of stable hemodynamics with minimal surges is applied during emergence
as well. The continuation of remifentanil infusion till the end serves this purpose
well. Dexmedetomidine has also been found to be a useful component of balanced anesthesia;
however, recommendations and evidence for the use of same are awaited. Potential advantages
of neuroprotection, preservation of neuronal function, cardiovascular stability, opioidsparing
effects, and minimal respiratory depression during awake procedures and intensive
care sedation render it a useful anesthetic adjunct.[40]
Postoperative pain management is an important consideration to prevent tachycardia
and increased myocardial oxygen demand, while also preventing surges in ICP. Multimodal
analgesia, including the use of patient- controlled analgesia, with acetaminophen
and opioids, as well as surgical infiltration with local anesthetic agents is useful.
Solution containing adrenaline, to reduce bleeding, should be avoided or used with
caution, due to the risk of arrhythmias. Attention must also be paid to treatment
of postoperative nausea and vomiting (PONV). Where postoperative mechanical ventilation
is continued, the decision to extubate must factor in the underlying cardiac disease.
Effective management of pain and PONV and use of shortacting opioids can help fast-track
extubation and prevent adverse outcome.
The use of postoperative intensive care, where indicated, is a good measure to improve
outcome. Patients having undergone neurosurgical procedures have been reported to
develop stress or Takotsubo’s cardiomyopathy, due to catecholamine surge. Intensive
care management should be multidisciplinary, with a considerable contribution of cardiology
team. The continuation of cardiac medication should be attempted as much as possible
and resumption of anticoagulation considered, where and when feasible. In cases in
which the surgery was performed as an emergency procedure, detailed cardiac evaluation
should be requested as soon as feasible.
Cardiac emergencies occurring intraoperatively could be challenging to manage. The
emergency could be due to the underlying pathology or the neurosurgical procedure.
These could range from arrhythmias and hemodynamic instability to cardiac arrest.
Cardiopulmonary resuscitation (CPR) could be particularly challenging due to positioning,
like the sitting or the prone position. Procedures such as craniotomy for tumors,
epilepsy surgery, and skull base surgery have reported incidences of bradycardia and
asystole, whereas posterior fossa surgery has been shown to result in ST elevation,
ventricular fibrillation, and asystole. CPR has been successfully applied in lateral
and sitting position; however, there is lack of standard guidelines related to management
of patients in these positions.[41] Most patients respond to removal of surgical stimulus (scalp traction), atropine,
and resuscitation.[42]
Conclusion
Patients with cardiac disease are at risk of significant adverse cardiac events while
undergoing neurosurgical procedures, elective as well as emergency. A careful evaluation
of risk factors, with the best possible optimization of concurrent illness, is the
most reasonable plan. The involvement of a multidisciplinary team should be the standard
practice.
