Widespread cardiovascular autonomic dysfunction in primary amyloidosis: does spontaneous hyperventilation have a compensatory role against postural hypotension?
OBJECTIVE
To investigate the possible causes of abnormal blood pressure control in light chain related (primary, AL) amyloidosis.


METHODS
Cardiovascular, autonomic, and respiratory response to passive tilting were investigated in 51 patients with primary amyloidosis (mean (SEM) age 56 (2) years) and in 20 age matched controls. Spontaneous fluctuations in RR interval, respiration, end tidal carbon dioxide, blood pressure, and skin microcirculation were recorded during supine rest and with tilting. The values were subjected to spectral analysis to assess baroreflex sensitivity and the autonomic modulation of cardiac and vascular responses.


METHODS
Tertiary referral centre.


RESULTS
Autonomic modulation of the heart and blood pressure was nearly absent in the patients with amyloidosis: thus baroreflex sensitivity and the low frequency (0.1 Hz) fluctuations in all cardiovascular signals were severely reduced (p < 0.01 or more), as were respiratory fluctuations in the RR interval, and no change was observed upon tilting. Despite reduced autonomic modulation, blood pressure remained relatively stable in the amyloid group from supine to tilting. End tidal carbon dioxide was reduced in the amyloid patients (p < 0.001) indicating persistent hyperventilation; the breathing rate correlated inversely with the fall in blood pressure on tilting (p < 0.05).


CONCLUSIONS
In primary amyloidosis, pronounced abnormalities in arterial baroreflexes and cardiovascular autonomic modulation to the heart and the vessels may be partly compensated for by hyperventilation at a slow breathing rate.
Bernardi
L
L
Department of Internal Medicine, IRCCS S. Matteo and University of Pavia, Pavia, Italy. lbern1ps@unipv.it
Passino
C
C
Porta
C
C
Anesi
E
E
Palladini
G
G
Merlini
G
G
D000686:Amyloidosis / Q000150:complications / Q000503:physiopathology*; D001158:Arteries / Q000502:physiology; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology*; D007022:Hypotension / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011187:Posture; D012119:Respiration; D012867:Skin / Q000098:blood supply; D016683:Supine Position; D018667:Tilt-Table Test
D002245:Carbon Dioxide