Page 107 - BH-2-3

Brain & Heart Adenosine cardiac arrest in aneurysm surgery

patient’s pupils were 3/3 mm in diameter, equally reactive clip placement. This outcome is consistent with the study
to light, and able to tolerate room air. conducted by Bebawy et al., which found that initial doses
5
of adenosine provide an anticipated momentary interval
3. Discussion of cardiac pause approximating 45 s. Normotension, sinus
AiCS describes a brief flow arrest technique to reduce rhythm, normoxemia, normocarbia, and normothermia
perfusion pressure and decrease aneurysm turgor, thereby are all aimed at once ROSC is achieved. As with our
facilitating clip ligation. Adenosine is efficacious and safely patient, vital signs spontaneously returned to baseline,
administered in combination with remifentanil + propofol with BIS and rSO remaining within the normal range, for
2
+ low-dose volatile anesthetic. Patient selection for AiCS which any silent episodes of cerebral ischemia have been
7
depends on the complexity of the aneurysm and the patient ruled out.
profile. In our patient, challenges related to aneurysm Differences in dose-response times may be attributed
include the location and depth of basilar tip aneurysm with to factors such as race, underlying vascular disease, site of
limited surgical exposure, a 2.5 cm giant aneurysm with a administration, and interactions with other medications. 10-15
wide neck, thin walls, and expected high turgor, and the In our patient, adenosine was administered through left
possibility of thrombosis and severe atherosclerosis. The subclavian central access to account for its short half-life
successful clipping of the basilar tip aneurysm in this case (<10 s) and total body clearance of about 30 s.
was primarily attributed to the use of AiCS. Adenosine, a known potent systemic vasodilator,
AiCS offers easy administration without advanced may cause persistent hypotension, leading to arrhythmia
preparation or complex logistical coordination with followed by asystole. The application of external
cardiovascular surgery. This technique also provides defibrillator pads is recommended for all patients who
maximal surgical field space to facilitate permanent clip receive adenosine to provide external pacing in the event
ligation without obstruction from temporary clips and of prolonged bradycardia or asystole, or for cardioversion
perforators, leading to decreased flow toward the aneurysm in cases of hemodynamically unstable atrial fibrillation. 16
without the risk of intraoperative rupture and better Adenosine induces vasodilation in healthy coronary
collapse of the aneurysm through global hypotension, arteries but does not affect atherosclerotic vessels. In
essentially negating the risk of bleeding. As compared to patients with cardiac ischemia, the vasodilation of healthy
7
other techniques for cardiac standstill, particularly rapid coronary arteries can lead to a paradoxical coronary
ventricular pacing, which enforces ventricular tachycardia vascular steal involving an increase in blood flow away
to consequently reduce stroke volume and cardiac output, from non-ischemic tissue. This may cause significant
17
AiCS provides rapid onset, offset, and high predictability in intraoperative ST depression, followed by sustained
providing a brief period of profound systemic hypotension ventricular tachycardia and atrial flutter, particularly in
with a low side-effect profile, making it a valuable tool patients with a known history of myocardial infarction.
18
8
in cerebrovascular surgery. The timing and expected Consequently, it is recommended to avoid adenosine
duration of flow arrest are carefully coordinated with administration in patients with severe left main coronary
the neurosurgeon for adequate aneurysm dissection and artery stenosis or extensive multi-vessel coronary artery
clip placement. Careful monitoring and neuroprotective disease. 5
strategies were applied to optimize cellular integrity
during this period through continuous propofol infusion, Cardiac conduction abnormalities may predispose
adequate fluid hydration, normoglycemia, normoxemia, patients to post-administration cardiac arrhythmia and
and normothermia. prolonged cardiac arrest, with an incidence of 1%. A study
has described a patient with pre-operative premature
Two approaches for AiCS have been described in the atrial contractions who developed atrial fibrillation after
earlier section of this paper. The dose-escalation technique adenosine administration, accompanied by a prolonged
starts with 6 – 12 mg IV of adenosine, titrated on demand, duration of cardiac asystole. 9
while the dose-estimation technique requires a single dose
of adenosine computed at 0.24 – 0.42 mg/kg IV to achieve Adenosine acts on A2B adenosine receptors
flow arrest expected to last within 30 – 60 s. Although in bronchial smooth muscles, thereby causing
5,6
4-7,19,20
both approaches are deemed safe, the dose-estimation bronchoconstriction. Several reports have noted
technique is favored as the efficacy of repeated adenosine bronchospasm after adenosine administration in patients
5,21,22
9
doses in asystolic duration is unpredictable. In our case, diagnosed with severe reactive airway diseases.
a single dose of 0.4 mg/kg IV was administered at the Finally, the breakdown and uptake of adenosine
neurosurgeon’s request, effectively facilitating permanent are inhibited by dypiridamole, nimodipine, and
12
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Volume 2 Issue 3 (2024) 4 doi: 10.36922/bh.3394