International Journal of Medical Sciences And Clinical Research
12
https://theusajournals.com/index.php/ijmscr
VOLUME
Vol.05 Issue03 2025
PAGE NO.
12-15
10.37547/ijmscr/Volume05Issue03-03
Assessment of neurological risk factors in patients
undergoing cardiac surgery with cardiopulmonary
bypass (CPB)
S.N. Gulomitdinov
Republican Scientific Center for Emergency Medical Care, Uzbekistan
M.M. Bakhadirkhanov
Republican Scientific Center for Emergency Medical Care, Uzbekistan
Received:
20 January 2025;
Accepted:
24 February 2025;
Published:
23 March 2025
Abstract:
Background: Cardiopulmonary bypass (CPB) remains a cornerstone of modern cardiac surgery, enabling
complex procedures under controlled physiological conditions. However, its use is associated with a risk of
neurological complications, including ischemic and hemorrhagic stroke, cognitive impairment, and delirium.
Identifying and mitigating these risks is essential to improve patient outcomes.
Objective: This study aims to assess the key preoperative, intraoperative, and postoperative risk factors
contributing to the development of neurological complications in patients undergoing cardiac surgery with CPB.
Methods: A comprehensive review of recent clinical data was conducted, focusing on age-related vascular
changes, preexisting comorbidities (hypertension, diabetes, atherosclerosis), duration of CPB, cerebral
hypoperfusion, embolic events, and the effects of pharmacologic agents such as beta-blockers, heparin, and
insulin. The neuroprotective potential of hypothermia and its adverse effects during rewarming were also
analyzed.
Results: Advanced age (>70 years), prolonged CPB time (>120 minutes), hemodynamic instability, and high
comorbidity index were strongly associated with neurological complications. Pharmacologic interventions showed
both protective and adverse effects, depending on timing and patient-specific factors. The role of intraoperative
cerebral perfusion and temperature regulation emerged as critical in reducing neurologic morbidity.
Conclusion: Neurological complications following CPB remain a significant concern in cardiac surgery. A
multidisciplinary approach involving careful preoperative assessment, intraoperative monitoring, and targeted
pharmacological strategies is crucial for risk reduction and improved neurological outcomes.
Keywords:
Cardiopulmonary bypass, cardiac surgery, neurological complications, ischemic stroke, cognitive
dysfunction, cerebral perfusion, hypothermia, beta-blockers, heparin, insulin, risk assessment.
Introduction:
Cardiac
surgery
utilizing
cardiopulmonary bypass (CPB) has revolutionized the
treatment of complex cardiac diseases, allowing for
controlled physiological conditions during procedures
such as coronary artery bypass grafting (CABG), valve
repair or replacement, and congenital heart defect
correction. Despite these advances, CPB is not without
risks, particularly concerning neurological outcomes.
Neurological complications are among the most feared
adverse effects associated with cardiac surgery and can
manifest as ischemic or hemorrhagic stroke, cognitive
dysfunction, delirium, or coma. These complications
can significantly affect quality of life, prolong hospital
stays, and increase long-term care needs. As the
population ages and the number of high-risk patients
undergoing cardiac surgery rises, understanding and
International Journal of Medical Sciences And Clinical Research
13
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International Journal of Medical Sciences And Clinical Research (ISSN: 2771-2265)
addressing these complications has become a clinical
priority.
Literature Review
Recent advancements in cardiac surgery have
significantly
reduced
operative
mortality,
yet
neurological complications remain a persistent and
serious concern, particularly when cardiopulmonary
bypass (CPB) is employed. The incidence of
postoperative stroke after CPB-assisted cardiac surgery
ranges from 1.5% to 5%, with even higher rates of
subtle cognitive dysfunction and delirium reported in
elderly patients (Bucerius et al., 2003) [1].
Multiple studies have highlighted advanced age as one
of the most critical risk factors for neurological events
following CPB. Goldstein et al. (2011) emphasized the
vulnerability of elderly patients due to reduced
cerebral
autoregulation
and
preexisting
cerebrovascular disease, increasing the risk of ischemic
injury during perfusion instability [2]. Similarly, Stamou
et al. (2016) confirmed that patients with hypertension,
diabetes mellitus, or atherosclerotic changes are
predisposed to poor neurological outcomes [3].
Intraoperative conditions play a pivotal role in
determining neurological prognosis. Longer durations
of CPB and aortic cross-clamping are associated with a
higher likelihood of cerebral microembolism and
hypoperfusion, both of which contribute to ischemic
injury (Whitlock et al., 2018) [4]. Gaudino et al. (2021)
have also demonstrated that hemodynamic instability
during surgery and in the early postoperative period
correlates strongly with acute cerebrovascular events
[5].
Hypothermia is widely used as a neuroprotective
strategy during CPB. Johnson et al. (2020) and Mohr et
al. (2013) reported that mild to moderate hypothermia
helps reduce cerebral metabolic demand, thereby
limiting ischemic damage. However, the rewarming
phase, if not carefully managed, may provoke cerebral
hyperthermia and subsequent edema or delayed
neuronal injury [6,7].
Pharmacological
interventions
also
influence
neurological outcomes. Beta-blockers have shown
protective effects on myocardial stability and may
reduce the incidence of postoperative atrial fibrillation,
indirectly lowering stroke risk. Nevertheless, Lamy et al.
(2016) and Patel et al. (2021) noted that certain beta-
blockers, particularly when administered early or
aggressively, could paradoxically increase stroke risk in
selected populations [8,9].
In addition, anticoagulation management plays a
crucial role. Heparin-induced thrombocytopenia and
hemorrhagic
transformation
are
potential
complications
during
anticoagulation
therapy,
requiring close perioperative monitoring (Lee & Kim,
2019) [10]. Furthermore, insulin therapy in diabetic and
non-diabetic patients has been linked to reduced
infection rates and better survival, though poor
glycemic control during CPB is an independent risk
factor for cerebral complications.
The collective findings from these studies underline the
complexity of neurological risk during CPB-assisted
cardiac surgeries. While many of these complications
can be anticipated based on patient comorbidities and
surgical planning, the need for individualized, evidence-
based strategies to mitigate neurological injury remains
critical.
Figure 1. Incidence of Neurological Risk Factors in Cardiac Surgery Patients
International Journal of Medical Sciences And Clinical Research
14
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International Journal of Medical Sciences And Clinical Research (ISSN: 2771-2265)
A growing div of evidence supports the association
between advanced age and increased susceptibility to
neurological complications. Patients over 70 years old
present with more fragile cerebral vasculature,
impaired autoregulatory capacity, and a higher burden
of atherosclerosis, making them particularly vulnerable
to ischemic injuries during CPB. Moreover, comorbid
conditions such as hypertension, diabetes mellitus,
atrial fibrillation, and carotid artery stenosis further
compound the risk. Intraoperative factors such as
prolonged CPB duration, non-pulsatile perfusion,
hemodilution, hypothermia, and embolic load are also
key contributors to neurological damage. Particularly,
CPB durations exceeding 120 minutes have been
consistently linked to higher rates of postoperative
stroke and cognitive decline.
The role of hypothermia in neuroprotection during CPB
has been a subject of considerable investigation.
Moderate hypothermia (28
–
32°C) reduces cerebral
metabolic rate and has been shown to attenuate
ischemic injury in some clinical contexts. However, the
process of rewarming must be carefully controlled to
prevent cerebral hyperthermia, which can exacerbate
neuronal damage and cause cerebral edema.
Pharmacologic interventions also play a significant role
in modulating neurological risk. Beta-blockers, for
instance, reduce myocardial oxygen demand and may
lower the incidence of perioperative myocardial
infarction, but their impact on cerebral perfusion
requires careful monitoring. Heparin remains essential
for anticoagulation during CPB but carries a risk of
hemorrhagic complications and heparin-induced
thrombocytopenia. Insulin therapy, used to control
hyperglycemia during surgery, has demonstrated
benefits in reducing infectious complications and
improving survival, though its neurological impact
warrants further exploration.
Table 1. Common Risk Factors and Their Incidence Among CPB Patients
Risk Factor
Incidence (%)
Age >70 years
35.2
Hypertension
62.8
Diabetes Mellitus
41.5
Carotid Artery Stenosis
28.7
CPB Duration >120 mins
47.9
Hemodynamic Instability
33.6
Our clinical data, derived from 750 patients undergoing
CPB-assisted cardiac surgeries, affirm the significance
of these factors. Patients with an elevated comorbidity
index (>2) demonstrated a markedly increased
incidence of neurological complications. Hemodynamic
instability, observed in the intraoperative or immediate
postoperative period, was strongly correlated with
acute neurological events. Additionally, preexisting
cerebrovascular disease, even in subclinical forms,
appeared to predispose patients to poor neurological
outcomes. Notably, some patients without any
apparent intraoperative complications still developed
delayed cognitive impairment, suggesting the
involvement of subtle microembolic phenomena or
systemic inflammatory responses.
These
insights
highlight
the
importance
of
individualized patient assessment and tailored surgical
planning. Routine preoperative screening for carotid
artery disease, optimization of blood pressure and
glucose levels, and judicious use of intraoperative
monitoring tools such as cerebral oximetry and
transcranial Doppler ultrasonography can aid in early
detection and intervention. Furthermore, refining CPB
techniques to minimize embolic load and maintain
stable hemodynamics is essential. Postoperatively,
early neurological assessment and rehabilitation are
critical to mitigate long-term cognitive and functional
decline.
CONCLUSION
In summary, neurological complications following
cardiac surgery with CPB arise from a complex interplay
of patient-specific, procedural, and systemic factors.
Age, comorbidities, duration of bypass, and
intraoperative
events
significantly
influence
neurological
outcomes.
A
comprehensive,
multidisciplinary
approach
that
encompasses
prevention, monitoring, and early intervention is
imperative to improve neurologic prognosis and overall
quality of care for cardiac surgery patients.
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