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Sudden Cerebral Vasoconstriction During Induced Polymorphic Ventricular Tachycardia and Fibrillation: Further Observations of a Paradoxic Response
Author(s) -
GRUBB BLAIR P.,
DURZINSKY DENNIS,
BREWSTER PAMELA,
GBUR CAROLYN,
COLLINS BRAD
Publication year - 1997
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1997.tb03537.x
Subject(s) - medicine , cardiology , cerebral circulation , middle cerebral artery , diastole , transcranial doppler , ventricular fibrillation , anesthesia , vascular resistance , vasoconstriction , ventricular tachycardia , cerebral blood flow , hemodynamics , blood pressure , ischemia
To determine the effect of induced polymorphic VT/VF on the cerebral circulation, transcranial Doppler (TCD) ultrasonography was used to prospectively assess changes in cerebral blood flow velocity during ICD implantation. Fourteen patients (13 men, 1 woman, mean age 58 ± 20 years, range 34‐74 years) who were survivors of an out of hospital cardiac arrest, were evaluated during routine ICD implantation. TCD ultrasonography was used to assess middle cerebral artery systolic velocity (V s ), diastolic velocity (Vd), pulsatility index (PI = V s – V d /V mean ) and resistance index (RI = V s ‐V a lV s ) before, during, and after DFT testing with alternating current induction of polymorphic VT/VF. In each of the 14 patients studied, concomitant with the abrupt onset of hypotension, TCD sonography demonstrated a 33%± 28% decrease in diastolic velocity, a 42%± 28% increase in systolic velocity, a 190%± 141% increase in FI, and a 44%± 19% increase in RI. These findings reflect an increase in cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the point of insonation of the middle cerebral artery. This response is paradoxic, as the expected response of the cerebral circulation to hypotension is vasodilation, but it is consistent with observations made in other acute hypotensive settings, such as tilt induced neurocardiogenic syncope.