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CHAPTER 28
Fig. 193k demonstrates pulse and blood pressure changes during the delivery of the baby
and placenta.
MECHANISM OF CARDIAC IRREGULARITIES
In analysing the mechanism of the irregularities of cardiac rhythm observed in this case,
it must first be pointed out that they are neither peculiar to pregnancy and labour in
women nor to ejaculations in men with high spinal cord lesions, but are just another
manifestation of exaggerated viscero-spinal reflex responses as an expression of the
autonomic stress syndrome as described following distension of the bladder (Guttmann
& Whitteridge, 1947; Guttmann, 1954). The difference in intensity and extent of the
cardiac irregularities is explained by the difference in duration, frequency and intensity
of the visceral stimulation. The increase in blood pressure as a result of the vasoconstric-
tion, which in lesions above T5/6 involves the greater part of the vascular bed of the body,
is most likely to be responsible for the observed bradycardia as part of a depressor reflex
response aroused by the intact aortic and carotic sinus nerves on the one hand and the
prevalence of vagal stimulation on the other. However, it seems likely that the stimulation
of the autonomic innervation of the heart itself is the decisive factor of the irregularities
of the heart rhythm. Whether and to what extent an increase of the level of catecho-
lamines, locally and/or circulating, may contribute to the development and intensity of
the cardiac arhythmias or may be even responsible as their initiator needs further studies.
In discussing this humoral factor, it must be remembered that irregularities of cardiac
rhythm may occur during and immediately after the acute hypertensive paroxysms due
to phaeochromocytoma. These arhythmias include extra-systoles and auricular fibril
lations (Heglin Rand & Holzmann, 1937; Espersen & Jorgensen, 1947), atrio-ventricular
block, dissociation with interference, and wandering pacemaker (Burges
et
a/., 1936;
Mortell & Whittle, 1945; Espersen & Jorgensen, 1947). Some of these arhythmias were
interpreted by Raab (1953) as continued primary sympathetic and simultaneous secon
dary vagal stimulation.
It is also of interest to compare our findings on cardiovascular changes described
during labour in women with cord lesions above T5/6 with those occurring in non-
paralysed women during labour. Adams & Alexander (1958) found that, during uterine
contractions, cardiac output increased by 19-7 per cent (dye dilution technique), and
there was a rise in mean blood pressure from 94 to 120 mm. The electro-cardiogram
during labour, unless non-paraplegic women are suffering from heart disease, shows no
abnormalities, apart from extra-systoles in sympatheticotonic individuals.
In conclusion, the observations made on pregnancy and labour in women with severe
lesions of the spinal cord are of great interest not only from a neuro-physiological point
of view but, even more, from a practical gynaecological standpoint. In particular, the
profound cardio-vascular reactions during the end of the first and second stages of labour
resulting in hypertension, bradycardia, headaches and cardiac arhythmias, sweating
and oculo-pupillary changes, etc., in women with cord lesions above Tf/6 must be most
carefully observed by both the medical and nursing attendants as they provide an impor
tant index of the progress of labour and the need for operative assistance. A rise of blood
