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Baroreceptor activity in patients with aortic stenosis prior to cardiac surgery
BARORECEPTOR M.E.
ACTIVITY Sinclair
IN PATIENTS
WITH
AORTIC
M.B.,Ch.B.,FFARCS, Nuffield
STENOSIS
A.
Department John Radcliffe OXFORD,
Fisher
PRIOR
TO CARDIAC
SURGERY
B.M.,B.S.,FFARCS
of Anaesthetics Hospital OX3 9DU
Intro&cticn It hss been noticed by the authors that patients presenting for aortic valve surgery for sortie stenosis suffered falls in blcad press on induction of anaesthesia which were not accunpaniedbysn increase inhesrt rate. Inviewofthese findingswe have investigatedthe teroreflex activity in patients with aortic stenosis before induction of anaesthesia and canpared the res.iLts with patients pricm to coronazy artery surgery. Method Twelve patients presenting for csrdio-pulmonsry bypass, b.S%Iri or IV, NyHk 2-3 WE studiedafter obtaining infomd consent, and the approval ofthslocal hospital ethics cam&tee. 6 patients (@oup 1) hsd aortic stenosis snd 6 patients (Group 2) coronary artery disease. Three of the patients in Group 1 had pure aortic stenosis and three had mixed stenosis and inccaipetence on catheter studies. All patients were premeditated with pspaveretua 15-2Cmp. and.hyoecineO.4mg. i.m. Intra-arterial (radial), central venous (superiorvenacava) andperipherslvenous cannulae were placed under local snalgesia and the electrocardiogram wssmonitoredcontinuoAyusingleadsinthe configuration. All WC variables were7-e =?$~a Mingograph I??@2ink jet recorder running at 50 mn sec. Follaving csnnulation patients were allowed to rest for 10 mirlutis . Baroreflex activity was assessed by measuring the reflex slowing of the heart rate produced by a rise in systolic pressure1 @-flowing the rapid injection of pheq'lephrine The dose was selected to produce a transient 1ugkg-. elevation of 20-30 ma Hg in systolic pressure. The R-R interval was plotted sgainst the systolic pressure ofthepreviousbeatandthedahasnalysed~1ines.r regression analysis. The derived slope was used as an expression of baroreflex sensitivity. Statistical evaluationoftheremittswasperfomasdusing the Mann Whitney 'Zr" test for un-paired non-parametric data.
located not only in the aortic arch, but also the carotid sinus, ventricles snd atria. In aortic valve disease, the left ventricular end-diastolic pressure (L.V.E.D.P.) ~COZIIES elevated. There is a decrease in the ccrnpliance ventricular wall as the ventricle hypertzophies.(" '?Z chsngesmayoccurinleftventriculsr fsilure(ypich, indogs, has been shown to reduce baroreflex activity. In aortic stenosis there is a dmnpened aortic pressure waveformwhichcould contributetothe resetting of the tsroreceptors in the aortic arch. Further studies sre in progress to determine if, by treating the aortic stencsis with a prosthetic valve, the teroreflexes return to normal. TmE 1.
IaN S.D.
BMfGLJX9ows
(WI slowing pernm.Hg. increase)
CRCUP1 (n=6)
Gi0.P 2 (n=6)
-1.49 4.18 3.59 -0.94 0.68 2.53 1.43 2.37
13.79 13.55
6.27
4.65 12.60
8.50 pCO.01
9.89 3.96
References 1. %vth,H.S., S1einht.P.. & Pickerinn.T.G. k auantitative -. method of assessing bsroreflex sensitivity. Circulation Research; XXIV: 104-121, 1969 2. Sobe1,B.E. and Roberts,R. Hypotensicn and syncope. In: BraunwaldE. ed..Hesrt Disease.k text&cd of candio;agukr4rsxdWne. %shingtcn: W.B.Sa&,ersCunpany: 3. Hig&,C.B., Vatner,S.F., &k&rg,D.L., & Braur&&d,E. Alterations in the taroreceptorreflex in conscious dogs with heart failure. J.Clin.Invest.; 51: 715-724, 1972.
Results hclroup l,+there were 4 msles and 2 females (mean age: 64 years (S.D 11.8)) and in Gmup 2 there were 5 males end 1 femeite (mean age: 52 years (S.D. 8.1)). There was no significant difference between the ages of the two groups. The slops ofthebaroreflex responses sre shcxe-~intablel. AlQ~qjesults fmnGroup2 fellwittithf! acc"ptednom!ml In (I&up 1, the three patients with mixed aortlc stenosis and incanpetence had flat -flex slopes. These were. below the nomal range. Wl six patients with aortic stenosis had significantly depressed bsroreflex slopes canparetl with the patients in Group 2 (p
ACTIVITY Sinclair
IN PATIENTS
WITH
AORTIC
M.B.,Ch.B.,FFARCS, Nuffield
STENOSIS
A.
Department John Radcliffe OXFORD,
Fisher
PRIOR
TO CARDIAC
SURGERY
B.M.,B.S.,FFARCS
of Anaesthetics Hospital OX3 9DU
Intro&cticn It hss been noticed by the authors that patients presenting for aortic valve surgery for sortie stenosis suffered falls in blcad press on induction of anaesthesia which were not accunpaniedbysn increase inhesrt rate. Inviewofthese findingswe have investigatedthe teroreflex activity in patients with aortic stenosis before induction of anaesthesia and canpared the res.iLts with patients pricm to coronazy artery surgery. Method Twelve patients presenting for csrdio-pulmonsry bypass, b.S%Iri or IV, NyHk 2-3 WE studiedafter obtaining infomd consent, and the approval ofthslocal hospital ethics cam&tee. 6 patients (@oup 1) hsd aortic stenosis snd 6 patients (Group 2) coronary artery disease. Three of the patients in Group 1 had pure aortic stenosis and three had mixed stenosis and inccaipetence on catheter studies. All patients were premeditated with pspaveretua 15-2Cmp. and.hyoecineO.4mg. i.m. Intra-arterial (radial), central venous (superiorvenacava) andperipherslvenous cannulae were placed under local snalgesia and the electrocardiogram wssmonitoredcontinuoAyusingleadsinthe configuration. All WC variables were7-e =?$~a Mingograph I??@2ink jet recorder running at 50 mn sec. Follaving csnnulation patients were allowed to rest for 10 mirlutis . Baroreflex activity was assessed by measuring the reflex slowing of the heart rate produced by a rise in systolic pressure1 @-flowing the rapid injection of pheq'lephrine The dose was selected to produce a transient 1ugkg-. elevation of 20-30 ma Hg in systolic pressure. The R-R interval was plotted sgainst the systolic pressure ofthepreviousbeatandthedahasnalysed~1ines.r regression analysis. The derived slope was used as an expression of baroreflex sensitivity. Statistical evaluationoftheremittswasperfomasdusing the Mann Whitney 'Zr" test for un-paired non-parametric data.
located not only in the aortic arch, but also the carotid sinus, ventricles snd atria. In aortic valve disease, the left ventricular end-diastolic pressure (L.V.E.D.P.) ~COZIIES elevated. There is a decrease in the ccrnpliance ventricular wall as the ventricle hypertzophies.(" '?Z chsngesmayoccurinleftventriculsr fsilure(ypich, indogs, has been shown to reduce baroreflex activity. In aortic stenosis there is a dmnpened aortic pressure waveformwhichcould contributetothe resetting of the tsroreceptors in the aortic arch. Further studies sre in progress to determine if, by treating the aortic stencsis with a prosthetic valve, the teroreflexes return to normal. TmE 1.
IaN S.D.
BMfGLJX9ows
(WI slowing pernm.Hg. increase)
CRCUP1 (n=6)
Gi0.P 2 (n=6)
-1.49 4.18 3.59 -0.94 0.68 2.53 1.43 2.37
13.79 13.55
6.27
4.65 12.60
8.50 pCO.01
9.89 3.96
References 1. %vth,H.S., S1einht.P.. & Pickerinn.T.G. k auantitative -. method of assessing bsroreflex sensitivity. Circulation Research; XXIV: 104-121, 1969 2. Sobe1,B.E. and Roberts,R. Hypotensicn and syncope. In: BraunwaldE. ed..Hesrt Disease.k text&cd of candio;agukr4rsxdWne. %shingtcn: W.B.Sa&,ersCunpany: 3. Hig&,C.B., Vatner,S.F., &k&rg,D.L., & Braur&&d,E. Alterations in the taroreceptorreflex in conscious dogs with heart failure. J.Clin.Invest.; 51: 715-724, 1972.
Results hclroup l,+there were 4 msles and 2 females (mean age: 64 years (S.D 11.8)) and in Gmup 2 there were 5 males end 1 femeite (mean age: 52 years (S.D. 8.1)). There was no significant difference between the ages of the two groups. The slops ofthebaroreflex responses sre shcxe-~intablel. AlQ~qjesults fmnGroup2 fellwittithf! acc"ptednom!ml In (I&up 1, the three patients with mixed aortlc stenosis and incanpetence had flat -flex slopes. These were. below the nomal range. Wl six patients with aortic stenosis had significantly depressed bsroreflex slopes canparetl with the patients in Group 2 (p