mechanism of pulmonary edema following sympathectomy

Unilateral pulmonary edema is unusual in presentation and is mainly seen in the re-expansion phase after pneumothorax, systemic-to-pulmonary shunt, parenchymal lung disease, and unilateral sympathectomy. The mechanisms of unilateral pulmonary edema include an increase in capillary blood flow, reduced surfactant, rapid re-expansion of a collapsed lung, and disruption of venular post-capillary sphincter function after sympathectomy.^1–3

http://onlinelibrary.wiley.com/doi/10.1111/j.1527-5299.2005.03861.x/full

Severe pain in 21.4% of patients 30 days post surgery

http://icvts.ctsnetjourna...ntent/full/10/6/919/TBL2

No significant change in tissue blood flow after sympathectomy

Lumbar sympathectomy is widely used in the treatment of peripheral vascular disease involving the lower extremity. The obvious increase in skin temperature postoperatively has led to the belief that there is a concommitant increase in perfusion of all tissues in the leg. 

Recent evidence suggests that this increase in total blood flow represents, in the main, arteriovenous shunting with a little, if any effect on the nutritive blood flow at the tissue level. Studies aimed at investigating the effect of lumbar sympathectomy on regional tissue circulation have utilized the local clearance of radioactive isotopes. No significant change in the clearance of these substances in muscle have been noted following lumbar sympathectomy in man.

Tissue Blood Flow in the Canine Lower Limb Following Lumbar SympathectomyVASC ENDOVASCULAR SURG November 1972 6: 227-238,

increased blood supply is associated with decreased vascular permeability

The influence of the sympathetic nervous system on capillary permeability was studied in cats. The dye penetration from the blood through the synovial membrane was tested by perfusing the two knee joints, one of which was deprived of its sympathetic nerve supply by unilateral lumbosacral
sympathectomy.
In confirmation of previous experiments, it was found in a great majority of experiments that, in spite of marked vasodilatation, the dye excretion was considerably reduced on the sympathectomised side.
A permeability factor under the influence of the sympathetic nervous system has been postulated; its character and mechanism is still unknown.
Further unpublished experiments seem to support the view that increased blood supply is associated with decreased vascular permeability.
Res Exp Med (Berl) 173, 1--8 (1978)

The effect of cervical sympathectomy on retinal vessel responses to systemic autonomic stimulation

The retinal vessel calibre responses to systemic sympathetic stimulation, were studied in nine patients (eight male; mean age: 31.7 years; range: 19-58 years) with unilateral disruption of their cervical sympathetic tract. All patients had ipsilateral decreased/absent facial sweating and a Horners syndrome, evidence of unilateral sympathetic denervation. Both eyes of each patient were studied and the results were analysed in two groups: the group of nine sympathectomised eyes and the control group of unaffected fellow eyes. During handgrip contraction there was a significant difference in the mean retinal arteriolar constriction (mean +/- SEM) between the group of sympathectomised eyes (4.6 +/- 0.89%) and control eyes (7.1 +/- 1.13%), p less than 0.01. Similarly, there was a significant difference in mean venule constriction during sustained handgrip contraction between the group of sympathectomised eyes (1.5 +/- 0.67%) and control eyes (4.9 +/- 0.98%), p less than 0.05. There was no significant difference in the mean rise in diastolic blood pressure between the two groups: control eyes +27.9 +/- 2.38 mmHg and sympathectomised eyes +27.8 +/- 2.25 mmHg. There was no correlation between the blood pressure and retinal vessel responses in either group. These results suggest that the sympathetic nervous system plays an integral role in retinal blood flow regulation.
http://www.ncbi.nlm.nih.gov/pubmed/2323469

GUSTATORY SWEATING AND OTHER RESPONSES AFTER SYMPATHECTOMY

Gustatory sweating on the head, neck and arms, often occurs after cervico-thoracic sympathectomy. Haxton (1948) reported an incidence of 36 percent, the same as in the present series. It was thought that some information about regeneration in the cervical sympathetic might be revealed by investigation of this surgical curiosity.

Although sweating is the common gustatory response after cervical sympathectomy, other changes are experienced. Haxton (1948) described associated paresthesia and flushing, gooseflesh may occur (Herxheimer, 1958) and vaso-constriction is reported in this paper. These occur together or separately and occasionally sweating might be absent. The subject has been confused by comparison with post-parotidectomy gustatory sweating which has a different mechanism (Glaister et al.,1958; Bloor, 1958).

Sweating is produced by cholinergic sympathetic fibres. In normal individuals both vasocontriction and gooseflesh are adrenergic. This also holds in gustatory responses.  Figure 2 shows blocking of sweating by atropine, whilst gooseflesh continues unchanged.
   The tingling sensations were described as being unlike normal sensation, and likened to plucking out of hair. In one patient in was so unpleasant that she refused to take a test stimulus. Flushing usually occurs on the upper chest and neck, and is an erythema with sharp demarcation, not associated with a rise in skin temperature.
   Of the patients, 29 were found to have gustatory responses, and 24 were studied in detail. Of 22 patients with sweating who could be studied, 11 had gooseflesh, 10 tingling, 6 flushing, and 4 vasoconstriction. Four patients, however, had no sweating and their gustator responses consisted of gooseflesh and tingling in one, tingling alone, and flushing in two. None of these four showed vasoconstriction.
   The stimulus for testing used was usually Worcester sauce, but specificity of the response was sometimes great, and one patient reacted only to boiled sweets made by one particular firm.

http://brain.oxfordjournals.org/content/92/1/137.extract   &
http://ang.sagepub.com/content/17/3/143.extract

cervical sympathectomy works systemically through hypothalamus endocrine system

Background: To investigate the general action of stellate ganglion block (SGB), we examined the effects of heat stimulation and cold stress on the behavior and stress hormone of the bilateral cervical sympathectomy rats as a long-term and repeated SGB model. Methods: Wistar's male rats were divided into three groups: control (C), sham operation (S) and sympathectomy (Sx) groups. After 2 weeks, two experiments were done. One was measurement of escape response time from the heat stimulus and the other was hormone measurement. Serum adreno-corticotropic hormone (ACTH), .ALPHA.-melanocyte stimulating hormone (.ALPHA.-MSH) and .BETA.-endorphine (.BETA.-END) levels were measured assigning 3 groups to 2 subgroups with and without cold stress. Results: Escape response time was significantly extended in the Sx group. ACTH in the Sx group was significantly higher than in other groups, but changes of ACTH by cold stress were similar in 3 groups. In the Sx group .ALPHA.-MSH was hardly changed by cold stress while .ALPHA.-MSH was significantly decreased in the S group. Changes of .BETA.-END by cold stress were similar in the S and Sx groups. Conclusions: These results suggest that SGB works systemically through hypothalamus endocrine system and affects stress hormone differently. (author abst.)

http://sciencelinks.jp/j-east/article/200402/000020040204A0020288.php

The cerebral vessels became hypersensitive to epinephrine after cervical sympathectomy

The cerebral vessels became hypersensitive to epinephrine after cervical sympathectomy.
HERTZMAN, A. B., AND DILLON, J. B.
Annual Review of Physiology
Vol. 4: 187-214 (Volume publication date March 1942)

post-sympathectomy neuralgia is proposed here to be a complex neuropathic and central deafferentation/reafferentation syndrome

http://www.ncbi.nlm.nih.gov/pubmed/8867242

Nerve regeneration commonly occurs following both surgical of chemical ablation

This systematic review found only one small study (20 participants) of good methodological quality, which reported no significant difference between surgical and chemical sympathectomy for relieving neuropathic pain. Potentially serious complications of sympathectomy are well documented in the literature, and one (neuralgia) occurred in this study.

The practice of sympathectomy for treating neuropathic pain is based on very weak evidence. Furthermore, complications of the procedure may be significant.

http://www2.cochrane.org/reviews/en/ab002918.html

This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2011 Issue 3, Copyright © 2011 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available inThe Cochrane Library (ISSN 1464-780X).

decreased brain metabolism, rather than an increased intracranial pressure, is the cause of decreased cerebral blood flow after superior cervical sympathetic ganglionectomy

"The reduced brain metabolism and consequently reduced cerebral perfusion in the late 

postsympathectomy period could account for reduction in CSF production (Bering3)."

"In support of the above statement we mention that on the late postsympathectomy (11 to 24 months) group of dogs besides the lowered CBF 

(31.36 ml/100 gm brain weight/minute) and MCP (79.3 mm NS) also a lowered MVP (46.5 mm NS) was found. These data indicate that cervicalsympathectomy has a profound and intricate effect on the dynamics of cerebrovascular fluids and probably, in the background of all observedphenomena, a decreased cerebral metabolism as a sympathectomy effect is the underlying cause. Correspondingly the cerebral metabolic rate ofoxygen (CMR O2) decreased to 2.94 and 2.43 ml of O2/IOO gm brain weight/ minute in the sympathectomized groups." 

"Decreased brain metabolism, rather than an increased intracranial pressure, is the cause of decreased cerebral blood flow after superior 

cervical sympathetic ganglionectomy."

http://archsurg.ama-assn.org/cgi/content/summary/90/3/418

Secondary Effects of Sympathectomy - Disturbance of Sexual Function

If a portion of the autonomic nervous system is removed to modify a specific disease process, unrelated physiologic mechanisms will also be affected. The degree to which these other mechanisms may be affected often governs the selection of operative procedures. The results produced by interfering with mechanisms other than those for which the operation is performed might be designated as side-effects or secondary effects. . . .

N Engl J Med 1951; 245:121-130July 26, 1951

http://www.nejm.org/doi/full/10.1056/NEJM195107262450401

We disagree that surgery and botulinum toxin are treatments of choice in severe cases of hyperhidrosis

The truth is exactly the opposite. Surgery is only rarely necessary, and the editorial quite properly warns of numerous surgical pitfalls, which include recurrence of hyperhidrosis, almost certain impotence, compensatory sweating, permanent neurological damage from anoxia, and death (their words). Botulinum toxin, which they recommend for axillary or plantar hyperhidrosis, requires 12 injections per axilla and 24-36 injections per foot. Even this horrendous procedure gives only 11 months' relief, and antibody formation may reduce long term efficiency.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1118569/

Iontophoresis should be tried before other treatments

Iontophoresis is easy to perform, effective in about 90% of patients in two studies with 54 and 30 participants, free of hazardous side effects, and well accepted by almost all patients.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1118569/

the Kuntz nerve played no part in the success or failure of ETS surgery

If you research the topic of ETS, you will come across various claims and counter-claims
about the importance or otherwise of the Kuntz nerve. The Kuntz nerve is a small nerve
fibre sometimes seen on the second rib not far from the main sympathetic chain. Its
function is not known in humans. Some web-sites on ETS claim success rates of up to
100% for facial blushing because they search for and destroy the Kuntz nerve(s). These
same people also claim to be able to correct failed ETS operations by reoperating and
destroying the Kuntz nerve.
At the meeting of the International Society for Sympathetic Surgery in Germany, May
2003, attended by a majority of the world’s experts in ETS surgery (including us), all but
one of the surgeons present were of the opinion that the Kuntz nerve played no part in the
success or failure of ETS surgery for facial blushing. We share this majority opinion.
www.lapsurgeryaustralia.com.au

"Sympathectomy is a technique about which we have limited knowledge, applied to disorders about which we have little understanding."

http://www.pfizer.no/templates/Page____886.aspx

diabetic autonomic neuropathy is due to a lesion of the sympathetic nerve supply to the skin

"We conclude that the diabetic anhidrotic syndrome, a form of diabetic autonomic neuropathy, is due to a lesion of the sympathetic nerve supply to the skin."

Diabetologia

Volume 22, Number 2, 96-99, DOI: 10.1007/BF00254836

 

Sympathectomy IS a (surgically caused) lesion of the sympathetic nerve supply to the skin 

to induce a patient's participation by appeal to their nonrational preferences, this is also a violation of their autonomy

In this paper we argue that the standard focus on problems of informed consent in debates about the ethics of human experimentation is inadequate because it fails to capture a more fundamental way in which such experiments may be wrong. Taking clinical trials as our case in point, we suggest that it is the moral offence of using people as mere means which better characterizes what is wrong with violations of personal autonomy in certain kinds of clinical trials. This account also helps bring out another important way in which the autonomy of the participants in clinical trials my be violated, even in cases where they have given informed consent to their involvement. Where relevant information about the trial is framed in such a way as to induce a patient's participation by appeal to their nonrational preferences, this is also a violation of their autonomy, and one which is distinct from a failure of informed consent. The underlying wrongness of both kinds of violations, we argue, is plausibly captured by the moral offence of using people as mere means.

MEDICAL EXPERIMENTATION, INFORMED CONSENT AND USING PEOPLE
DEAN COCKING 1 JUSTIN OAKLEY 1
1 Centre for Human Bioethics Monash University

Fake websites in the service of the ETS industry - who protects the patients?

Mia:
Many surgeons compete with each other for the attention of the 'costumer' in the saturated market of the www. Adaptations to a business model raises ethical questions that should have been explored long ago and should have raised the ire of the medical community. The occasional whimper of discord is silenced by the cacophony of (ignorant) enthusiasm. Not quite the scientific behavior one would expect.

How does the entrepreneurial aspect of medicine impact on the information patients are given? In the area of elective procedures, is it in the interest of the service provider to provide full disclosure? Does self-interest influence and modify how the information is conveyed? How information morphs into little facts and more emoting. to appeal to the irrational in all of us. To be seduced.

Fake websites that pretend to be independent,  informative, with the sole raison d'etre to praise the surgeon's skill, expertise and experience, - and to hook the patient into reading more on the surgeons' website, with many obvious links to the surgeon on every page.
Why are predatory practices of medical professionals tolerated?

In 70 % compensatory sweating severe, recurrence rates were 15% and 19% at 1 and 2 years after surgery

In T2 and T3 resection, all patients experienced Compensatory Sweating and over 70% of the patients felt it was severe. Even in T2 resection, 90% of patients experienced CS and in 50% of these it was severe. High rates of CS are reported in Asian countries with hot and humid climates.

In T2 resection, recurrence rates were 15% and 19% at 1 and 2 years after surgery.It was not rare for a patient to experience recurrence more than 3 years after surgery.
Motoki Yano, MD, PhD and Yoshitaka Fujii, MD, PhD

Volume 138, Issue 1, Pages 40-45 (July 2005)

The results of endoscopic sympathectomy deteriorate progressively from the immediate outcome

British Journal of Surgery ISSN 0007-1323

1999, vol. 86, no1, pp. 45-47 (12 ref.)

a strong association of autonomic dysfunction and impaired cerebral autoregulation

Furthermore, we found a strong association of autonomic dysfunction and impaired autoregulation indicated by a correlation between the LF/HF ratio and Sx (p <>

Influences of autonomic dysbalance and mental state during withdrawal are suggested. The finding of an affected autoregulation during acute withdrawal might indicate an increased risk for cerebro-vascular disease.

Drug and Alcohol Dependence
Volume 110, Issue 3, 1 August 2010, Pages 240-246

Conditions arising after Sympathectomy

After stellate ganglion blockade: HORNER'S SYNDROME

• Drooping eyelid
• Constricted pupil (impaired vision in low light)
• Absent/reduced sweating one side of the face and head
• Redness of eyes
• Facial flushing
  

After regional sympathectomy: DUMPING SYNDROME:

• Rapid emptying of the stomach: lower end of small intestine fills too quickly
• Early dumping: nausea/vomiting/bloating/diarrhoea/shortness of breath
• Late dumping: 1-3 hours after eating: weakness/sweating/dizziness
• Both types may co-exist.

http://www.theaword.org/index.php?option=com_content&view=article&id=223:conditions-arising-after-sympathectomy&catid=84:the-sympathetic-nervous-system&Itemid=41

Surgical sympathectomy is one of the causes or Orthostatic Hypotension

Causes of Orthostatic Hypotension

Peripheral

Amyloidosis

Diabetic, alcoholic, or nutritional neuropathy

Familial dysautonomia (Riley-Day syndrome)

Guillain-Barré syndrome

Paraneoplastic syndromes

Pure autonomic failure (formerly called idiopathic orthostatic hypotension)

Surgical sympathectomy

http://www.merckmanuals.com/professional/sec07/ch069/ch069d.html

Other causes of autonomic dysfunction: sympathectomy

Patients with progressive autonomic dysfunction (including diabetes) have little or no increase in plasma noradrenaline and this correlates with their orthostatic intolerance (Bannister, Sever and Gross, 1977). In patients with pure autonomic failure, basal levels of noradrenaline are lower than in normal subjects (Polinsky, 1988). Similar low values are observed in patients with sympathectomy and in patients with tetraplegia. (p.51)

The finger wrinkling response is abolished by upper thoracic sympathectomy. The test is also abnormal in some patients with diabetic autonomic dysfunction, the Guillan-Barre syndrome and other peripheral sympathetic dysfunction in limbs. (p.46)

Other causes of autonomic dysfunction without neurological signs include medications, acute autonomic failure, endocrine disease, surgical sympathectomy . (p.100)

Anhidrosis is the usual effect of destruction of sympathetic supply to the face. However about 35% of patients with sympathetic devervation of the face, acessory fibres (reaching the face through the trigeminal system) become hyperactive and hyperhidrosis occurs, occasionally causing the interesting phenomenon of alternating hyperhidrosis and Horner's Syndrome (Ottomo and Heimburger, 1980). (p.159)

Disorders of the Autonomic Nervous System

By David Robertson, Italo Biaggioni

Edition: illustrated

Published by Informa Health Care, 1995

ISBN 3718651467, 9783718651467

Bilateral sympathectomy produced fatal heart block in a few of their experiments

Mendlowitz. Schauer, and Gross⁴ pointed out that the heart rate became slower after removal of the sympathetic chain, but this bradycardia was only temporary. Bilateral sympathectomy produced fatal heart block in a few of their experiments.

American Heart Journal
Volume 22, Issue 4, October 1941, Pages 545-548

bradycardia and other cardiac complications are common side effects?

The most common side effects of sympathectomy are compensatory sweating, gustatory sweating and cardiac changes including decreasing heart rate, systolic-diastolic and mean arterial pressure. The mechanism of bradycardia and other cardiac complications that develop after thoracic sympathectomy are still unclear.

http://tipbilimleri.turkiyeklinikleri.com/abstract_54802.html

"It is a lie that sympatholysis may specifically cure patients

with unqulified "reflex sympathetic dystrophy". This was already stated by the father of sympathectomy, Rene Leriche, more than half a century ago.
...it is not an error. but a lie. While conceptual errors are not only forgivable, but natural to inexact medical science, lies, particularly when entrepreneurially inspired are condemnable and call for a peer intervention.

J. Neurology (1999) 246: 875-879

After thoracoscopic sympathectomy for hyperhidrosis, very severe discomfort and hyperhidrosis occurred with alarming frequency and intensity

"After thoracoscopic sympathectomy for hyperhidrosis, very severe discomfort and hyperhidrosis in the neighboring non-sympathectomized regions occurred with alarming frequency and intensity."
(p.879)

Cousins and Bridenbaugh's Neural Blockade in Clinical Anesthesia and Pain Medicine by Michael J Cousins, Phillip O Bridenbaugh, Daniel B Carr, and Terese T Horlocker
Wolters Kluwer Health
Edition: 4 - 2008

Lack of disclosure to ETS patients is unethical and would be criminal in a just society

It is the doctor's moral and ethical duty to provide you with full and honest disclosure of the facts prior to surgery. The whole doctrine of informed consent is to prevent patients from having to realize they made a mistake in hindsight. You shouldn't have had to find out from a former patient's wife that the surgery would cause drenching sweating on your back. It was Garza's job to do that. He completely lied to you regarding the supposed reversibility. Anyone who goes through medical school knows that can't crush a nerve with a metal clamp, remove it later and have the nerve return to normal functioning.

Although it is not possible to predict exactly what will occur in each individual case, there is nearly 100 years of published scientific and medical research available on the effects of sympathectomy. That research paints a very different picture of the effects of this surgery than the one presented to patients considering this surgery. That's the issue. Generally, they lie and tell patients that CS is inconsequential in all but a tiny fraction of cases and simply fail to disclose a huge number of verified adverse effects of the surgery. They take advantage of the patient's ignorance on medical matter. It's unethical and would be criminal in a just society.

In short, you do have a way of knowing what will likely occur as a result of the surgery before you have it done. All the information necessary to make an informed decision exists. It's just not getting to patients.

http://etsandreversals.yuku.com/reply/22927/Would-you-do-it-again#reply-22927

Surgical sympathectomy listed as neurologic disorder

Other neurologic disorders
- Idiopathic orthostatic hypotension
- Multiple sclerosis
- Parkinsonism
- Posterior fossa tumor
- Shy-Drager syndrome
- Spinal cord injury with paraplegia
- Surgical sympathectomy
- Syringomyelia
- Syringobulbia
- Tabes dorsales (syphillis)
- Wernicke's encephalopathy
Dizziness: Classification and Pathophysiology
The Journal of Manual and Manipulative Therapy, Vol. 12, No 4 (2004)

Effects of Sympathectomy on Muscle

We have previously reported functional and histological studies in five beagle dogs with unilateral lumbar sympathectomy. Three months later, fatiguability in the gracilis muscles was increased on the denervated sides, and this was associated with an increase in the relative distribution of FT fibres. Biochemical studies now show that these changes were associated with an increase in cytosolic protein without change in DNA content; this is consistent with
an increase in cell size. There was a reduction in the proportion of slow myosin light chain isoforms from 50 ± 7 to 34 ± 6%. Noradrenaline levels were increased on the denervated sides but this may reflect greater vascularity. Calcium content did not correlate with fibre type but there was a positive relation with both noradrenaline content (r= 0·73;
P<0·05) and DNA content (r= 0·84; P<0·05). It is concluded that sympathectomy induces several biochemical changes in skeletal muscle which constitute a change and increase in fast myosin light chain synthesis and a corresponding fibre type transformation.

Clinical Physiology (Oxford, England) 1988 Apr; vol 8 (issue 2): pp 181-91

2.
The objective of this paper was to study the effect of sympathetic innervation on morphological and histochemical aspects of skeletal muscle tissue. Rabbit masseter muscle was studied using histochemical and immunohistochemical methods for periods of up to 18 months post-sympathectomy. The morphological and enzymatic characteristics of control masseter muscles were similar on both the left and right sides. The main features were muscle fibres with a mosaic pattern and a predominance of type IIa fibres, followed by type I. Type IIb fibres showed very low frequency. Sympathectomized animals showed varying degrees of metabolic and morphological alterations, especially 18 months after sympathectomy. The first five groups showed a higher frequency of type I fibres, whilst the oldest group showed a higher frequency of type IIb fibres. In the oldest group, a significant variation in fibre diameter was observed. Many fibres showed small diameter, atrophy, hypertrophy, splitting, and necrosis. Areas with fibrosis were observed. Thus cervical sympathectomy induced morphological alterations in the masseter muscles. These alterations were, in part, similar to both denervation and myopathy.

International Journal of Experimental Pathology
Volume 82, Issue 2, pages 123–128, April 2001

Sympathectomy limits blood flow to a vital organ like the brain

1. Acta Physiol Scand. 2000 Sep;170(1):33-8.

Middle cerebral artery blood velocity during exercise with beta-1 adrenergic and unilateral stellate ganglion blockade in humans.

Ide K, Boushel R, Sørensen HM, Fernandes A, Cai Y, Pott F, Secher NH.

Department of Anaesthesia, The Copenhagen Muscle Research Centre, University of Copenhagen, Rigshospitalet, Denmark.

A reduced ability to increase cardiac output (CO) during exercise limits blood flow by vasoconstriction even in active skeletal muscle. Such a flow limitation may also take place in the brain as an increase in the transcranial Doppler determined middle cerebral artery blood velocity (MCA V(mean)) is attenuated during cycling with beta-1 adrenergic blockade and in patients with heart insufficiency. We studied whether sympathetic blockade at the level of the neck (0.1% lidocaine; 8 mL; n=8) affects the attenuated exercise - MCA V(mean following cardio-selective beta-1 adrenergic blockade (0.15 mg kg(-1) metoprolol
i.v.) during cycling. Cardiac output determined by indocyanine green dye dilution, heart rate (HR), mean arterial pressure (MAP) and MCA V(mean) were obtained during moderate intensity cycling before and after pharmacological intervention. During control cycling the right and left MCA V(mean) increased to the same extent (11.4 1.9 vs. 11.1 1.9 cm s(-1)). With the
pharmacological intervention the exercise CO (10 1 vs. 12 1 L min(-1); n=5), HR (115 4 vs. 134 4 beats min(-1)) and delta MCA V(mean) (8.7 2.2 vs. 11.4 1.9 cm s(-1) were reduced, and MAP was increased (100 5 vs. 86 2 mmHg; P < 0.05).

However, sympathetic blockade at the level of the neck eliminated the beta-1 blockade induced attenuation in delta MCA V(mean) (10.2 2.5 cm s(-1)). These results indicate that a reduced ability to increase CO during exercise limits blood flow to a vital organ like the brain and that this flow limitation is likely to be by way of the sympathetic nervous system.

PMID: 10971220 [PubMed - indexed for MEDLINE]