The use of a cardiopulmonary heart pump during
coronary artery bypass grafting surgery does not
significantly damage such high-level mental tasks as
thinking, reasoning and remembering, according to a study
by Johns Hopkins researchers recently published in
Neurology.
CABG surgery is effective for the relief of angina and
reducing the risk of a heart attack but has been widely
feared to cause "pump-related" damage to the cerebral
cortex, according to Guy M. McKhann, a professor in the
Department of
Neurology at the School of Medicine.
To gauge whether there was a clinical basis for this
concern, McKhann led a nonrandomized study comparing the
cognitive abilities of on-pump CABG patients, off-pump CABG
patients, nonsurgical patients with coronary artery disease
and heart-healthy individuals.
The results of the study showed that on-pump CABG
patients had no significant differences in their
higher-level mental functions than the other groups tested,
McKhann said.
"This outcome should be reassuring to both patients
and surgeons engaged in on-pump CABG surgeries," he
said.
The study, conducted between September 1997 and
September 2003, involved 380 individuals--140 on-pump CABG
patients, 72 off-pump CABG patients, 99 nonsurgical
patients with coronary artery disease and 69 heart-healthy
patients. The on-pump CABG patients and the nonsurgical
patients with coronary artery disease were exclusively
Johns Hopkins-based. The off-pump CABG patients came from
Johns Hopkins; Sinai Hospital and University of Maryland
Medical Center, both in Baltimore; Washington Adventist
Hospital, Takoma Park, Md.; and Pinnacle Health System,
Harrisburg, Pa.
Study participants were given a battery of
standardized neuropsychological tests, which were repeated
three months and 12 months later.
Test scores were sorted and combined into eight areas:
verbal memory, visual memory, language, attention span,
visuoconstruction (the ability to copy a complex figure),
motor speed (the time to perform motor activity, such as
writing the alphabet), psychomotor speed (the time to
complete an action that requires some planning) and
executive function (the ability to plan ahead and make
judgments).
The Center for Epidemiologic Studies Depression scale
and Functional Status Questionnaire were also administered
at baseline and follow-up, and all subjects were tested by
the same team of investigators, who traveled to the sites
to examine patients. Previous test results were not
reviewed before subsequent testing so that testers were
unlikely to be able to bias results based on such
knowledge.
Self-reporting of well-being was included in the study
in the areas of memory, mental arithmetic, personality and
reading newspapers and books. For example, subjects were
asked whether they thought their personality had improved,
changed for the worse or stayed the same over time and
since the previous interview. Reading, defined as whether
or not a patient typically read either newspapers or books,
was assessed at each visit.
At the start of the study, subjects with coronary
artery disease (CABG on-pump, CABG off-pump and
nonsurgical) had overall lower performance than the
heart-healthy group in several cognitive domains. But by
three months, all groups had improved, a result that
McKhann said was most likely due to familiarization with
the testing procedures. Between three and 12 months, there
were minimal changes in individual subjects for all groups,
and no consistent differences between the CABG and off-pump
patients were observed.
"These results offer no evidence that the cognitive
test performance of on-pump CABG patients differed from
that of off-pump control groups with coronary artery
disease over a one-year period," McKhann said.
Other researchers who participated in the study were
O.A. Selnes, Department of Neurology, School of Medicine;
W.A. Baumgartner and M.A. Grega, Department of Surgery,
School of Medicine; L.M. Borowicz Jr. and M.M. Bailey, the
Zanvyl Krieger Mind/Brain Institute; and S.J.E. Barry and
S.L. Zeger, Department of Biostatistics, Bloomberg School
of Public Health.
The study was supported by a grant from the National
Institute of Neurological Diseases and Stroke of the
National Institutes of Health, a Johns Hopkins Medical
Institutions General Clinical Research Center grant and the
Dana Foundation.
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