Transcranial Doppler Waveforms During Intra-aortic Balloon Pump Counterpulsation for Vasospasm Detection After Subarachnoid Hemorrhage

Abstract

Background: Transcranial Doppler ultrasound is a standard screening tool for vasospasm after subarachnoid hemorrhage. Prevention of vasospasm-induced delayed cerebral ischemia after subarachnoid hemorrhage depends on optimization of cerebral perfusion pressure, which can be challenged by neurogenic stress cardiomyopathy. Intra-aortic balloon pumps have been utilized to augment cerebral perfusion, but they change the transcranial Doppler waveform, altering its interpretability for vasospasm screening.

Objective: To assess the features of the transcranial Doppler waveform that correlate with vasospasm.

Methods: We retrospectively reviewed cases of subarachnoid hemorrhage that underwent same-day transcranial Doppler ultrasound and angiography. Transcranial Doppler waveforms were assessed for mean velocity, peak systolic velocity, balloon pump-augmented diastolic velocity, and a novel feature, "delta velocity" (balloon pump-augmented velocity - systolic velocity). Relationship of flow velocity features to vasospasm was estimated by generalized estimating equation models using a Gaussian distribution and an exchangeable correlation structure.

Results: There were 31 transcranial Doppler and angiography pairings (12 CT angiography/19 digital subtraction angiography) from 4 patients. Fourteen pairings had proximal vasospasm by angiography. Delta velocity was associated with proximal vasospasm (coefficient -6.8 [95% CI -9.8 to -3.8], P < .001). There was no significant correlation with proximal vasospasm for mean velocity (coefficient -13.0 [95% CI -29.3 to 3.4], P = .12), systolic velocity (coefficient -8.7 [95% CI -24.8 to 7.3], P = .29), or balloon pump-augmented velocity (coefficient -15.3 [95% CI -31.3 to 0.71], P = .06).

Conclusion: Delta velocity, a novel transcranial Doppler flow velocity feature, may reflect vasospasm in patients with subarachnoid hemorrhage and intra-aortic balloon pumps.

Figure 1.

IABP-induced changes to arterial waveform. A normal arterial waveform A and an arterial waveform altered by the intra-aortic balloon pump (IABP) B. Inflation of the IABP just prior to the dicrotic notch creates the characteristic double-peaked waveform in which the augmented diastolic pressure is higher than the systolic pressure.

Figure 2.

Measurement of systolic velocity and peak diastolic intra-aortic balloon pump (IABP)-augmented velocity. Examples of transcranial Doppler ultrasound waveform from the R middle cerebral arterial (MCA) without A and with B IABP counterpulsation. Note that the software automatically labeled “systolic velocity” is actually the peak diastolic IABP-augmented velocity (PDAV).

Figure 3.

Delta velocity vs proximal vasospasm. An elevation of the delta velocity (PDAV – systolic velocity) was significantly associated with the presence of proximal vasospasm (coefficient –6.8 [95% CI –9.8 to –3.8], P < .001).