Key-words:
Atrial fibrillation - neurosurgery - positioning
Introduction
Transient atrial fibrillation (AF) is a well-known cardiovascular rhythm disturbance
during the perioperative period. It could be due to acute alcohol intake, myocardial
infarction, acute carditis, hyperthyroidism, pulmonary embolism, etc., It is associated
with increased cardiovascular morbidity and mortality.[[1]] It has been associated with cancer; however, the literature related to its occurrence
in patients with brain tumors is limited.[[2]],[[3]] Here, we would like to discuss a rare case of transient AF in a patient with a
right-sided sphenoid wing meningioma who was posted for surgical excision. For submission
of this case report, institutional review board approval is not required, but informed
consent was obtained from the patient's gaurdian.
Case Report
A 64 year old female of weight 75 kg and height 160 cm (body mass index [BMI] – 29.3
kg/m2) presented with urinary incontinence and left-sided weakness. Her only significant
past history included regular treatment for hypertension (tablet amlodipine 5 mg/day)
for 3 years and no other cardiac abnormality. Preoperative neurological examination
revealed left-sided hemiparesis (muscle power – 4/5). The examination of the cardiorespiratory
system was unremarkable. She was anticipated to have difficult peripheral intravenous
(IV) access. Preoperative assessment was done one day before surgery and was within
normal limits, including electrocardiogram (ECG) [[Figure 1]]. Magnetic resonance imaging (MRI) of the brain revealed a right-sided sphenoid
wing meningioma with a mass effect and midline shift of 11 mm. A craniotomy and excision
of the tumor under general anesthesia (GA) was planned. On the day of surgery, the
American Society of Anesthesiologists standard monitors such as ECG, noninvasive blood
pressure (NIBP), and pulse oximetry (SpO2) were attached in the operation theater.
The baseline vitals on the monitor showed heart rate (HR) which varied between 153
and 160/min, NIBP – 126/80 mmHg, and SpO2 – 99%. On the monitor, ECG showed an irregular
rhythm with absent P waves on lead 2 and V5 (new-onset AF). The pulse oximetry waveform
was irregular in height and rhythm. The patient's pulse was irregularly irregular
on palpation, suggestive of AF. The patient was given IV esmolol 30 mg, which resulted
in a decrease of HR by 10 beats/min for 10 min, following which the arrhythmia persisted
at the same rate (153–160/min). Transthoracic echocardiography done intraoperatively
revealed grossly normal cardiac contractility with no clot in the left atrium, and
the decision to proceed with surgery was made in view of the neurosurgical emergency
after taking high-risk informed consent for perioperative major adverse cardiovascular
events from the patient's guardian. Emergency cardiac drugs were kept ready. The left
radial artery was cannulated for invasive blood pressure monitoring before the induction
of anesthesia. GA was induced with IV morphine 9 mg, propofol 100 mg, and atracurium
30 mg. GA was maintained with isoflurane/oxygen. The patient was anesthetized and
intubated with a 7.5 mm cuffed endotracheal tube. Postintubation, the patient's head
was kept in the neutral position for insertion of the central line in the right subclavian
vein, by removing the pillow under the patient's head and placing a sandbag in the
interscapular area. Just after positioning the patient as such, the arrhythmia reverted
to normal sinus rhythm on ECG with a HR of 72 beats/min [[Figure 2]]a and [[Figure 2]]b. The patient continued to have normal sinus rhythm for the rest of the intraoperative
period. Surgical positioning was done, i.e., supine position with the head rotated
to the left side by 30° and neck slightly extended with the malar eminence as high
as possible. The patient's head was secured with four pins and was in an extended
position at a face plane angle of 25°–30° and the neck relatively less flexed at an
angle of 30°. Moreover, it was ensured that a gap of at least two fingers was present
between the mentum and clavicle to avoid extensive rotation of the neck and venous
engorgement. The surgery was completed successfully. Postoperatively, ECG showed normal
sinus rhythm and HR. The patient was extubated on postoperative day (POD) 2 and discharged
on POD 5 in stable condition.
Figure 1: Preoperative electrocardiogram
Figure 2: (a) Intra-operative baseline electrocardiogram suggestive of atrial fibrillation
(b) Normal sinus rhythm
Discussion
Different types of cardiovascular changes have been described in the literature following
acute brain insults due to trauma, intracranial hemorrhage, stroke, etc. However,
we could not find relevant literature where inappropriate head-and-neck positioning
in the less compliant brain due to brain tumor has resulted in transient cardiac arrhythmias.
Neuroanatomic connections between the brain and the heart are provided by parasympathetic
ganglia and the intermediolateral gray columns of the spinal cord, thereby affecting
the HR and rhythm. The right side is predominantly associated with HR control and
the left side with the origin of arrhythmias. Loss of right-sided predominance of
parasympathetic control has been shown to cause sinus tachyarrhythmias only in patients
with right-sided strokes.[[4]] Pawar et al. have reported a case where a 57 year old woman suffered a road traffic
accident following syncopal attacks, and on presentation, AF was present; further,
brain imaging revealed a left temporal mass.[[3]] In our case, the patient had a right-sided sphenoid wing meningioma, and hence
laterality of the tumor may have also played a role in the onset of AF.
Abrupt occurrence and cessation of AF is an unusual finding in our case which lead
to the hypothesis that the pillow placed under the patient's head resulted in neck
flexion and engorgement of neck vein in a patient with compromised intracranial compliance
whose MRI already demonstrated raised ICP.[[5]] The raised ICP might have caused transient AF, which reverted to normal sinus rhythm
with a neutral placement of neck while positioning for central line insertion.
A pillow of 7–9 cm height has been advised to obtain the “sniffing position” with
approximately 35° cervical flexion (to align the pharyngeal and laryngeal axis) and
maximal head extension at the atlanto-occipital joint (to align the oral axis with
pharyngeal and laryngeal axis) for intubation. Park et al. compared three different
pillow heights (3, 6, and 9 cm) with a sniffing position to determine the optimal
pillow height for the best laryngoscopic view and found that best views were obtained
with the use of a 9 cm pillow.[[6]] However, pillows of 6 cm height were better suited in short-necked patients with
the thyromental distance of <7 cm.[[6]],[[7]] Our patient had a short neck, the pillow with 9 cm height might have caused more
neck flexion than required. This might have contributed to transient AF in our case.
A “ramped” position with horizontal alignment of the external auditory meatus with
the sternum is recommended in obese patients. Although this patient did not classify
as obese by definition (BMI ≥30), a ramped position might have been a more appropriate
position during intubation (BMI 29.3 kg/m2 with a short neck).[[8]]
In 15 patients undergoing elective neurosurgery (with ICP <20 mmHg, majority of patients
had intracranial tumors), Mavrocordatos et al. observed collective effects of head,
neck, and operation table on ICP in 15 different positions.[[5]] They demonstrated that flexion with rotation caused significant increases in ICP
(neutral position– 8.8 mmHg, right rotation and flexion– 16.2 mmHg and left rotation
and flexion- 15.8 mmHg).Hence, the changes in ICP associated with head and neck positioning
may contribute to cardiovascular disturbances in susceptible patients who lie on the
steep part of the intracranial compliance curve. This may lead to unnecessarily delay
in the surgical procedure which can further worsen neurological status and affect
overall outcome.
None of the anesthetic drugs routinely used are known to control AF. However, propofol
has been shown to have both pro and anti-arrhythmic properties.[[9]] Case reports have suggested the role of propofol in the reversion of AF; however,
its effect was noted at 90 s after administration of propofol bolus of 1 mg/kg (peak
action of IV propofol).[[10]] Animal studies have indicated that morphine may have antiarrhythmic properties,
but other studies have found no effects.[[11]] A review of literature did not reveal antiarrhythmic properties for any of the
other drugs used. The patient continued to have AF after receiving all these agents,
and hence it is unlikely that these agents had any effect on the suppression of AF.
IV esmolol 30 mg was also given to counter the AF, but it did not produce the desired
result. Moreover, the suppression of AF was a sudden occurrence, immediately after
removing the pillow from under the patient's head. No drug bolus/new drug was introduced
at that point, and hence it is unlikely that the suppression of AF was a response
to the effect of any drugs used.
To conclude, in neurosurgery, head-and-neck position is an important component of
the armamentarium to prevent or treat raised ICP. Our case highlights an unusual occurrence
of transient AF in patient with a brain tumor that may be attributed to the disturbances
in the neurocardiac axis following head-and-neck positioning during a neurosurgical
intervention. Hence, the neuroanesthetist should always be more vigilant regarding
the optimal head-and-neck positioning to prevent undue venous congestion, rise in
ICP, and cardiac arrhythmias.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form, the patient's guardian has given her consent for her images and other
clinical information to be reported in the journal. The guardian understands that
her name and initials will not be published and due efforts will be made to conceal
identity, but anonymity cannot be guaranteed.
