Table I.

TCD Studies Measuring HITS and Cognitive Function in Cardiac Surgery

Author & Year	Study Type	Surgical Procedure	n	Cognitive Assessments Definition of Decline	NP Time	Cognitive Findings in Relation to TCD
Motallebzadeh, 2007[13]	Randomized Prospective	CABG -on-pump -off-pump	212	8 NP tests Composite score	Preop; Postop discharge, 6 weeks, & 6 months	HITS: on-pump (1605) vs. off- pump (9) (p<.01) After adjustment for age, education, and on-pump status, HITS did not remain in the cognitive decline regression model
Bokeriia, 2007 [54]	Prospective	CABG Valve ± CABG	62	11 NP tests Z-scores on individual tests	Preop; Postop 2–4 weeks	HITS: CABG (463) vs. Valve ±ABG (881) (p<.01) Total HITS not associated with cognitive function Left ME may predict verbal memory performance (p=.07) Right ME may affect psychomotor function (p=.07)
Stroobant, 2006[55]	Prospective	CABG -on-pump -off-pump	50	7 NP tests 20% decline on 20% of tests	Preop; Postop 6 days and 6 months	HITS: on-pump (335) vs. off- pump (145) (p<.01) No correlation between number of HITS and NP tests
Abu-Omar, 2006[41]	Randomized Prospective	CABG -on-pump -off-pump	25	1 Verbal Memory Task	Preop; Postop 4 weeks	HITS: on-pump (254) vs. off- pump (35) (p<.01) No difference in preop and postop testing HITS negatively correlated with MRI prefrontal activation (r=−.61, p<.01)
Stygall, 2003[9]	Longitudinal Prospective	CABG	107	11 NP Tests Residualized change scores Simple change scores	Preop Postop 5 years	ME predicted of NP decline at 5 years (unadjusted)
Whitaker, 2003 & 2006 [56,57]	Randomized Prospective	CABG -3 arterial filters	192	9 NP tests ≥1 SD decline in ≥2 tests	Preop; Postop 6–8 weeks	Arterial filter decreases HITS HITS not correlated with NP change ≤35 HITS associated with better NP recovery
Lund, 2003[58]	Randomized Prospective	CABG -on-pump -off-pump	52	8 NP tests 20% decline on ≥2 tests	Preop; Postop 3 months	HITS: on-pump (90) vs. off-pump (16) (p<.01) No correlation between HITS and NP impairment
Eifert 2003[59]	Prospective Randomized	CABG +/− Valve -Aortic filter	24	4 reaction time tests for attention and alertness	Preop; Postop 7 days	No difference between filter and non filter group with respect to HITS or NP function HITS were not correlated with NP performance
Nadareishvili, 2002 [60]	Prospective	Valve Replacement	36	4 Cognitive screening measures Measures analyzed individually	Postop 3 months	No correlation between HITS and cognitive decline (p > 0.05)
Browndyke 2002[61]	Prospective Controlled	CABG or Valve	27	5 NP Measures Measures analyzed individually	Preop; Postop 10 days and 30 days	Surgical subjects perform worse than controls Surgical subjects performed worse at 10days than at 30 days No correlations between HITS and NP performance
		Controls	25
Fearn, 2001 [62]	Prospective	CABG	65	Cognitive Drug Research Battery (4 tests)	Preop; Postop 1, 8, & 24 weeks	57% of patients had >200 HITS HITS correlated with decreased memory accuracy
Jacobs, 1998[42]	Prospective	CABG ± Valve	18	10 NP Tests	Preop; Postop 10 days, 3 months	12 patients with completed TCD PET scan uptake correlated with HITS No relationship of HITS and NP performance
Braekken, 1997[63]	Prospective	CABG and Valve Replacement;	40	10 NP Tests ≥1 SD decline in ≥1 test	Preop; Postop 2 months	Valve repair patients with cognitive deficits were more likely to have increased HITS counts. CABG patients had lower HITS counts
Clark, 1995 [64]	Randomized Prospective	CABG	41	Neurobehavioral Cognitive Status Examination Cognitive decline not defined	Preop Postop 5–10 days	Gradient effect of HITS with NP decline in 35% of those with >60 HITS

CABG - coronary artery bypass graft; + CABG - indicates with or without coronary artery bypass graft; HITS - high intensity transient signals; ME - microemboli; MRI - magnetic resonance imaging; NP-neuropsychological; On-Pump- utilizing the cardiopulmonary bypass machine/pump; Off-pump - surgery not requiring use of the cardio-pulmonary bypass machine/pump; Preop – preoperative; Postop- postoperative; SD- standard deviation