Velocity of microemboli and transit time from the heart to the brain in patients with patent foramen ovale and artificial heart valves.
There is no information about the physical behavior of microemboli en route from their source to the cerebral vessels. Microemboli could abide to a certain laminae, and have a consistent velocity, or wander between different laminae, and keep changing their velocity. Two hundred and seventy four microemboli were recorded by transcranial Doppler (TCD) in six patients with artificial valves, and 119 microemboli were recorded in response to i.v. injection of saline agitated with air in eight patent foramen ovale (PFO) patients. Transit time of microemboli, calculated based on their arrival time at the cerebral vessel (site of monitoring) was explored as a possible function of their measured velocity at the detection point. In the PFO group, the relation between embolus velocity and transit time was: embolus velocityPFO = -41.8 * transit time + 100.6, whereas for the artificial heart valve group it was: embolus velocityValve = -22.6 * transit time + 67.1. Transit time, in both clinical groups, was inversely related to velocity (p < 0.001), thus, early appearing emboli had higher velocity and vice versa. The inverse relation between transit time and measured terminal velocity implies a consistent velocity per microemboli en route, in both groups. Thus, a flow abided to a certain laminae seems to characterize microemboli.
Telman
Gregory
G
Department of Neurology, Rambam Medical Center, Haifa, Israel. g_telman@rambam.health.gov.il
Kouperberg
Efim
E
Sprecher
Elliot
E
Reisner
Shimon
S
Goldsher
Dorit
D
Yarnitsky
David
D
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D002560:Cerebrovascular Circulation; D006331:Heart Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006344:Heart Septal Defects, Atrial / Q000150:complications / Q000503:physiopathology*; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000000981:diagnostic imaging*; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000502:physiology*; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*