Pulse pressure and perioperative stroke

Abstract

Purpose of review: Central pulse pressure (PP), a marker of vascular stiffness, is a novel indicator of risk for perioperative morbidity including ischemic stroke. Appreciation for the mechanism by which vascular stiffness leads to organ dysfunction along with understanding its clinical detection may lead to improved patient management.

Recent findings: Vascular stiffness is associated with increased mortality and neurologic, cardiac, and renal injury in nonsurgical and surgical patients. Left ventricular hypertrophy and diastolic dysfunction along with microcirculatory changes in the low vascular resistance, high blood flow, cerebral and renal vasculature are seen in patients with vascular stiffness. Pulse wave velocity and the augmentation index have higher sensitivity for detecting of vascular stiffness than peripheral PP as the hemodynamic consequences of vascular stiffness are secondary to alterations in the central vasculature. Vascular stiffness alters cerebral autoregulation, resulting in a high likelihood of having a lower limit of autoregulation more than 65 mmHg during surgery. Vascular stiffness may predispose to cerebral hypoperfusion, increasing vulnerability to ischemic stroke, postoperative delirium, and acute kidney injury.

Summary: Vascular stiffness leads to alterations in cerebral, cardiac, and renal hemodynamics increasing the risk of perioperative ischemic stroke and neurologic, cardiac, and renal dysfunction.

Figure 1.

Demonstration of radial artery and central aortic arterial pressure waveform from an elderly patient demonstrating vascular stiffness and a young patient with a compliant vasculature. The peripheral arterial waveforms of the elderly (top left panel) and younger patient (lower left panel) appear morphologically similar. The central aortic pressure waveform, however, demonstrate difference imparted by dynamics imposed on the waveform by elevated pulse wave velocity and early return of reflected waves. The arrow marks the point of return to the central circulation of the reflected arterial waves. The elderly patient (top right panel) demonstrates loss of diastolic augmentation and elevation of systolic pressure with the hallmark elevation in augmentation index (point between inflection of the pressure wave on the arterial waveform upstroke and systolic pressure. Reused with permission from Barodka, V.M., et al [8].

Figure 2.

Pulse wave velocity measurements from an elderly and young patient. The pulse wave is measured with an applanation sensor placed on the carotid artery and femoroal artery representing central and peripheral arterial circulation, respectively. The pulse wave velocity is defined as the difference between distance between the carotid and femoral artery pulse upstroke divided by time (measured from the ECG. Reused with permission from Barodka, V.M., et al [8].