Download Factors Affecting the Acute Response, Increase in Exercise

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Medical Research Society
were recorded continuously. A mean of 3.6
episodes per patient of ST depression were
Two patients had a
recorded (48% painful).
mean of 3.5 episodes of ST elevation (mean 2.5
painful).
In the 6 patients with ST
depression only, all but one episode was
preceded by arousal and lightening of the
sleep pattern on the EEG coinciding with a
sudden increase in heart rate and bodily
movement. One episode of ST depression was
preceded by central apnoea lasting 25 seconds
when the oxygen saturation fell by 16%
(96 to 80%). I n the 2 patients with episodes
of ST elevation and depression, these changes
were not preceded by arousal, apnoea o r
increases in heart rate and both patients had
angiographically proven coronary spasm and
no significant coronary stenoses. The other
6 patients had severe 3 vessel disease.
Thus, nocturnal ischaemia in the presence
of coronary disease is likely to be
precipitated by increased myocardial oxygen
demand produced by arousal, body movements
in sleep and sudden increases in heart rate.
FACTORS AFFECTING THE ACUTE RESPONSE,
INCREASE IN EXERCISE PERFORMANCE AND SURVIVAl IN
PATIENTS RECEIVING VASODILATOR THERAPY FUR
CHRONIC BEART FAILURE
R. CANEPA-ANSON, J.R. DAWSON, S.R. RELIBESI,
G.C. SUTTON and P.A. POOLELWILSON
National Heart Hospital, London, England
Prediction of the effects of vasodilator therapy remains an unresolved clinical problem. We
performed multiple regression analyses between
clinical and haemodynamic variables under control
conditions, the acute haemodynamic response,
changes in long term exercise performance and
survival in patients treated with pirbuterol, an
oral El-adrenoceptor agonist, because of severe
chronic heart failure (NYHA class 2-4 despite
digoxin and frusemide 80-250 mg/day).
Seventy
patients .were studied acutely and 63 began treatment with pirbuterol 20 mg t.i.d. for 3 months.
Acutely the combination of high initial systemic resistance and low stroke volume correlated
with the acute fall in resistance (p<O.Ol), but
there were no correlations with the acute change
in stroke volume. Thirty-one patients had exercise tests before and after 3 months treatment.
Increased duration of treadmill exercise at 3
months correlated with increased stroke volume
acutely (p<O.Ol) and long term (p<0.025), hut
not with falls in left ventricular filling pressure or systemic resistance. The 20 patients who
died on treatment with pirbuterol differed from
survivors in havin larger hearts (p<0.05), lower
"HA class (p<O.OlT and lower stroke volume (p<
0.001) before treatment, but not in their acute
haemodynamic response.
Control resting haemodynamics predict the acute
fall in systemic resistance with vasodilator therapy, hut not the increase in stroke volume.
Long term improvement in exercise performance may
be anticipated from increases in stroke volume
but not from falls in left ventricular filling
pressure or systemic resistance, either acutely
or long term. SuPvival is unaffected by the acute response to vasodilator therapy but correlates with the severity of cardiac dysfunction
before the introduction of vasodilator therapy.
Resting haemodynamics cannot predict left ventricular reserve. Vasodilator therapy should be
introduced earlier in the course of the disease
if patients are to survive long enough to
benefit.
116 ALPHA ADRENOCEPTOR BLOCKADE IMPROVES
EXERCISE TOLERANCE IN ANGINA PECTORIS
P. COLLINS and D.J. SHERIDAN
Department of Cardiology, Welsh National School
of Medicine, Cardiff CF4 4XN
The afterload reducing effects of post Synaptic
alpha receptor blockade should improve exercise
capacity in patients with exertional angina.
TO test this we carried out a double blind crossover trial of indoramin, a post synaptic alphal
adrenoceptor blocking drug, versus placebo in
15 patients with chronic stable angina and
positive exercise tests, 13 of whom had angiographically proven coronary artery disease.
Each patient received indoramin 25 mg t.i.d.
(shown i n a preliminary pilot study not to reduce
blood pressure below 110/60 mmHg) and matching
placebo for 3 weeks each, separated by a washout
For ethical reasons treatperiod of 1 week.
ment with beta blockers and nitrates were continued throughout the study period, although none
were receiving calcium antagonists. Exercise
tests to the onset of angina during which total
oxygen consumption was measured, were performed
prior to the study and at the end of each treatment period.
Indoramin increased exercise
duration (17,%), from 402+39 (SEM) to 470+35
seconds (p < 0.01), and total oxygen consumption
during exercise (2l%), from 9.9Ll.Z to 12.021.3 1
(p<O.Ol), whereas the peak double product was
changed little, 18311+795 to 1893451263. Close
correlations were observed between oxygen
consumption and exercise duration, but neither
correlated well with the maximal double product.
One patient developed impotence but elected to
continue the study, one patient withdrew from
the study because of marked tiredness while on
active treatment. Five patients complained of
tiredness during active treatment, and two during
placebo. Thus alpha receptor blockade provides
additional benefit to patients with stable
angina, who are receiving beta blockers and
nitrates.
117 POTENTIALLY HAZAPXIUS RESPONSES To
SALBUTAMOL GIVEN BY NEBULISER
S.R. SMITH M.J.
KENDALL AND C. RYDER
Department of Therapeutics and Clinical
Pharmacology, The Medical School, Fdgbaston,
Birmingham Bl5 2TH
The administration of beta agonists by nebuliser
is well established in the2treatment of patients
with airways obstruction. When given intravenously however these agents have been shown to
produce a variety of unwanted responsesmcluding
tachycardia and hypokalaemia. We have therefore
studied the administration of salbutamol by
nebuliser to determine whether these systemic
effects occur in response to inhaled drugs.