ANS Pathophys Flashcards
Which agents will affect a transplanted heart? Which will not?
Epi, isoproterenol, glucagon
(directly stimulate SA node)
will not work: indirect agents
neo, glyco, atropine
Why is a transplanted heart not responsive to indirect stimulation of the SA node/indirect agents?
neo, glyco, atropine
heart rate depends on the SA node’s intrinsic rate
no influence from ANS (vagus nerve or cardiac accelerator fibers)
T/F:
Neo can cause bradycardia in a transplanted heart.
False
only happens in someone with an intact SNS
Expected resting heart rate of a transplanted heart
100-120
(relies on SA node’s intrinsic rate)
A transplanted heart will eventually respond to circulating catecholamines. How?
A & B adrenergic receptors are intact
Paragangliomas (formerly called glomangiomas)
- neuroendocrine tumors from neural crest cells
- origin similar to pheochromocytoma but also in extra-adrenal locations
- surrounding the aorta, in lung, near the carotid artery, glossopharyngeal nerve, jugular vein, and middle ear
Multiple system atrophy (MSA) with autonomic dysfunction predominating
“Shy-Drager syndrome”
degeneration of:
- locus coeruleus,
- intermediolateral (IML) column of the spinal cord,
- peripheral ANS neurons
manifests as orthostatic hypoTN
ANS dysfunction in patients with MSA. How do they respond to GA?
compensation for vasodilation and tachycardia from voltailes may be impaired = exaggerated hypoTN
transplanted hearts have a fixed HR, so that means the CO is dependent on…
preload
sensitive to hypovolemia!
CO = HR x SV
T/F:
transplanted hearts are sensitive to epi
true
What happens if you give a transplant heart verapamil?
AV block
the transplanted heart will not show reflex tachycardia from these 2 agents
- hydralazine
- nifedipine
T/F:
Transplanted hearts are resistant to BBs.
False
more sensitive
EKG changes with transplanted heart
two p waves
(intrinsic SA node & transplanted heart)
does not affect cardiac function
What cardiac reflex remains intact with transplanted hearts?
bainbridge
the SA node stretch will directly increase its firing rate
these 2 maneuvers do not affect a transplanted heart rate
valsava
carotid sinus massage
most common cuase of cardiac denervation in non-cardiac surgery patients
diabetic ANS dysfxn
giving cholinesterase inhibitors to a transplanted heart
no bradycardia
but
will activate PNS elsewhere so give with anticholinergic
derived from neural crest cells
autonomic ganglia
and
chromaffin cells
of the adrenal medulla
T/F:
Paraganglioma tumor size determines the signs and symptoms.
false
location
Paragangliomas rarely secrete vasoactive substances, but when they do, ___ secretion is the most common (thus mimicking a pheochromocytoma).
norepinephrine (hypertension)
paragangliomas
Serotonin or kallikrein secretion can cause carcinoid-like symptoms such as …
bronchoconstriction, diarrhea, headache, flushing, and hypertension.
Histamine or bradykinin release can cause bronchoconstriction and hypotension.
can be used to treat carcinoid-like syndrome
Octreotide
bronchoconstriction, diarrhea, headache, flushing, and hypertension.
paragangliomas
Anesthetic concern
- Cranial nerve paragangliomas (glossopharyngeal, vagus, and hypoglossal) can impair swallowing, aspiration, airway obstruction.
- if in the IJ, surgical dissection risks air embolism
