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Results for “Autonomic Denervation”

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PubMed1973

Neural control of counter-regulatory events during glucopenia in man.

The effect of autonomic denervation on the metabolic and hormonal responses during intracellular glucopenia in man was investigated. 2-Deoxy-d-glucose (2 DG), a competitive inhibitor of glucose metabolism, was administered intravenously to nine normal volunteers and to five patients, three with complete cervical cord transection (C-6) and two with idiopathic orthostatic hypotension. Before, during, and after a 20 min infusion of 2 DG (50 mg/kg) plasma concentrations of glucose, lactate, FFA, total catecholamines, immunoreactive insulin (IRI), human growth hormone (HGH), and cortisol were determined for periods up to 150 min. In control subjects, the initial elevation of FFA, glucose. HGH, and cortisol corresponded with the rise in total catecholamines, with maximal levels attained at 60 min, lactate rose at a slower rate, reaching peak levels at 150 min: although no change in IRI was noted. In contrast, 2 DG-induced glucopenic stress in the autonomic denervated subjects was characterized by no detectable catecholamine release or significant rise in glucose, FFA, lactate, or IRI. However, HGH and cortisol responses in four of the five patients were of a similar or greater magnitude than controls.These studies demonstrate that the integrity of the sympathoadrenomedullary axis is essential for the counter-regulatory response to intracellular glucopenia in man. Cortisol and HGH have no apparent role in these events.

Adrenal Medulla↗

PubMed2001

Neuroanatomical basis for first- and second-order representations of bodily states.

Changes in bodily states, particularly those mediated by the autonomic nervous system, are crucial to ongoing emotional experience. A theoretical model proposes a first-order autoregulatory representation of bodily state at the level of dorsal pons, and a second-order experience-dependent re-mapping of changes in bodily state within structures such as cingulate and medial parietal cortices. We tested these anatomical predictions using positron emission tomography and a human neurological model (pure autonomic failure), in which peripheral autonomic denervation prevents the emergence of autonomic responses. Compared to controls, we observed task-independent differences in activity of dorsal pons and context-induced differences in cingulate and medial parietal activity in PAF patients. An absence of afferent feedback concerning autonomically generated bodily states was associated with subtle impairments of emotional responses in PAF patients. Our findings provide empirical support for a theory proposing a hierarchical representation of bodily states.

Aged↗

PubMed1998

Denervation of eccrine glands in patients with familial amyloidotic polyneuropathy type I.

OBJECTIVE: To study the alterations in the structure and innervation of eccrine glands in familial amyloidotic polyneuropathy (FAP) type I with Val 30 Met transthyretin mutation. BACKGROUND: Anhidrosis of the distal lower limbs is a prominent feature of FAP type I. METHODS: Qualitative and morphometric study of amyloid deposition, eccrine glands, and their innervation in nine patients with FAP type I (duration of sensory symptoms, 8.4 +/- 3.9 years [mean +/- SD]; range, 3 to 15 years) and seven control subjects. RESULTS: On light microscopy, the endoneurium of cutaneous nerve fascicles had no definite amyloid deposition. Amyloid deposition was observed around eccrine glands in seven of nine patients. On electron microscopy, no focal destruction and degeneration of eccrine glands or ducts and of Schwann cell processes with or without nerve terminals or unmyelinated axons were observed in relation to adjacent amyloid deposition. Secretory vacuoles and granules of dark cells were markedly decreased in some secretory coils. Nerve terminals and unmyelinated axons of eccrine glands were considerably fewer in patients than in control subjects, and denervation was prominent in all patients. A few nerve terminals and unmyelinated axons of eccrine glands were present in patients who had experienced sensory symptoms for 3, 5, and 6 years, but were absent in patients with sensory symptoms for more than 7 years. CONCLUSIONS: Eccrine glands are markedly to totally denervated in patients with FAP type I and chronic sensory symptoms. The extent of denervation indicates the severity of autonomic denervation and therefore may suggest the timing of liver transplantation.

Adult↗

PubMed2003

Effects of transection and extrinsic denervation and a model of autotransplantation of the porcine jejunoileum on cholesterol biodynamics.

BACKGROUND/PURPOSE: Small bowel transplantation impairs enteric function, necessitating transection, extrinsic denervation, and ischemia-reperfusion of the small intestine. The authors investigated how each of these nonimmunologic insides of the transplantation procedure modulates biodynamics of cholesterol and absorption of lipids. METHODS: Twenty-three pigs with similar food, cholesterol, and fat intake underwent sham laparotomy (group 1), transection (group 2), extrinsic jejunoileal denervation (group 3), or a model of autotransplantation, including extrinsic jejunoileal denervation with in situ ischemia-reperfusion (group 4). Serum lipids, absorption, and excretion of cholesterol, bile acids, and fat were determined after 8 weeks. Plasma cholesterol precursors and plant sterols, respective markers of cholesterol synthesis, and absorption, were measured after 2 and 8 weeks. RESULTS: When compared with sham laparotomy and transection groups, denervation and autotransplantation significantly decreased weight gain and increased plasma cholesterol precursors and fecal excretion of bile acids. In relation to sham operated animals, transection alone modestly increased plasma plant sterols at 2 weeks and biliary secretion and mass absorption of cholesterol. The latter changes were not observed after denervation or autotransplantation, ie, fractional and total absorption of cholesterol were significantly decreased in autotransplanted pigs when compared with transected controls. As compared with all the other groups, autotransplantation significantly increased bacterial metabolites of neutral sterols in feces and net fecal elimination of cholesterol, mainly as bile acids. CONCLUSIONS: Extrinsic autonomic denervation of the jejunoileum, with or without synchronous ischemia-reperfusion, results in increased cholesterol synthesis, bile acid malabsorption, and decreased weight gain. Cholesterol malabsorption may develop gradually after intestinal autotransplantation, and even a short period of ischemia further impairs absorptive function of the denervated jejunoileum, resulting in increased fecal elimination of cholesterol mainly as bile acids.

Anastomosis, Surgical↗

PubMed2004

Octreotide in the treatment of small intestinal dysfunction after a model of jejunoileal autotransplantation in the pig.

Enteric denervation and ischemic injury contribute to dysmotility and malabsorption following intestinal transplantation. We hypothesized that, by prolonging bowel transit and by ameliorating dysmotility, octreotide (OT) may improve cholesterol and bile acid absorption after jejunoileal autotransplantation. Seventeen pigs with fixed food intake underwent either jejunal transection (n = 6), or jejunoileal autotransplantation, which includes extrinsic autonomic denervation, lymphatic interruption, and in situ cold ischemia (n = 11). Five randomly chosen autotransplanted animals received intramuscular long-acting OT (10 mg) once a month. After 8 weeks, weight gain, intestinal transit time, fecal excretion of bile acids and cholesterol, and fractional cholesterol absorption were determined. Jejunal and ileal specimens were collected for histochemical analyses. Plasma cholestenol and campesterol, respective markers of cholesterol synthesis and absorption, were measured after 2 and 8 weeks. Following jejunoileal autotransplantation, octreotide treatment significantly increased the median intestinal transit time from 22.8 to 24.8 h and the median body weight gain from 166 to 187%. Jejunoileal autotransplantation significantly increased fecal bile acid excretion, plasma cholestenol, and bacterially modified fecal neutral sterols, and decreased absorption of cholesterol, plasma campesterol, and biliary cholesterol secretion. These changes were not significantly modified by OT treatment. Bowel wall and mucosal structure, mucosal proliferation, and weight or microvilli showed no statistically significant differences between autotransplanted animals with or without OT treatment. Findings of the present study suggest that octreotide prolongs intestinal transit time and improves weight gain after jejunoileal autotransplantation, but has no effect on malabsorption of cholesterol and bile acids.

Animals↗

PubMed2004

Growth hormone selectively improves intestinal cholesterol absorption after jejunoileal autotransplantation in pigs.

BACKGROUND/PURPOSE: Small bowel transplantation impairs enteric function and causes malabsorption of cholesterol and bile acids. Growth hormone stimulates intestinal absorptive function. The authors hypothesized that long-term growth hormone therapy could improve absorption of bile acids and cholesterol after autotransplantation of the jejunoileum. METHODS: Sixteen pigs with similar food, cholesterol, and fat intake underwent either sham laparotomy or a model of jejunoileal autotransplantation, including extrinsic autonomic denervation, lymphatic interruption, and in situ cold ischemia. Five randomly chosen autotransplanted animals received daily growth hormone treatment for 8 weeks. Serum lipids, absorption, and excretion of cholesterol, bile acids, and fat were determined after 8 weeks. Mucosal morphometrics, proliferation, and enzyme activities were determined. Plasma cholesterol precursors and plant sterols, respective markers of cholesterol synthesis and absorption, were measured after 2 and 8 weeks. RESULTS: After jejunoileal autotransplantation, growth hormone treatment significantly increased body weight gain, cholesterol absorption efficiency from 45.1% to 62.1%, plasma campesterol to cholesterol proportions, and biliary secretion of cholesterol. With or without growth hormone treatment, autotransplantation significantly increased fecal bile acid excretion, plasma cholesterol precursors, fecal bacterially modified neutral sterols, mucosal thickness of the ileum (but not jejunum), and intestinal transit time when compared with sham-operated animals. Crypt cell proliferation, mucosal enzyme activities, and microvilli showed no differences between the groups. CONCLUSIONS: These findings suggest that growth hormone treatment selectively improves cholesterol, but not bile acid absorption, after autotransplantation of the jejunoileum.

Animals↗

PubMed1988

Dysautonomia in a cat.

Autonomic dysfunction was diagnosed in a 2.5-year-old spayed domestic shorthair cat. The cat had an 8-day history of progressive anorexia, signs of depression, constipation, weight loss, and intermittent regurgitation. Physical examination findings were signs of depression, dehydration, cachexia, bradycardia, bilateral nonresponsive mydriasis, prolapse of both nictitating membranes, dry oral and nasal mucous membranes, and urinary bladder atony. Thoracic radiography revealed megaesophagus. The cat lacked esophageal motility and had a decreased gastric emptying rate. Providing adequate fluid intake, electrolyte balance, and nutrition is a major problem in the management of dysautonomic cats. We were able to provide adequate nutritional support for this patient, using total parenteral feeding and, later, enteral nutrition using a nasogastric tube. Results of an ocular pharmacologic study indicated that the mydriasis and prolapse of the nictitating membrane were attributable to complete autonomic denervation of the eye. Using the method described, topical, autonomic-stimulating agents may assist the clinician in diagnosing dysautonomia in the feline. This report describes a syndrome that is well recognized in the United Kingdom and has the potential to develop in the United States.

Animals↗

PubMed1995

Specific effects of zatebradine on sinus node function: suppression of automaticity, prolongation of sinoatrial conduction and pacemaker shift in the denervated canine heart.

We evaluated the cardiac electrophysiological effects of zatebradine in eight anesthetized and autonomically denervated canines, with particular emphasis on the effects on sinus node automaticity and sinoatrial conduction (SACT), both at rest and after atrial overdrive pacing. Sinus node function was assessed by using the recorded sinus node electrogram and also by applying a previously validated mathematical model of sinus node function which allows separate evaluation of effects of pacing on SACT and suppression of automaticity. Other standard electrophysiological parameters also were measured. Tests were performed before and after incremental doses of zatebradine (0.0625, 0.125 and 0.25 mg/kg). Zatebradine caused a significant, dose-related increase in cardiac cycle length. There also was a significant, dose-related increase in both suppression of automaticity and SACT (independent of changes in cycle length) after zatebradine. The only other significant electrophysiological effect was a relatively minor increase in the ventricular effective refractory period (13%). Higher doses of zatebradine were associated with spontaneous pacemaker shift characterized by loss of the sinus node electrogram and variation in P-wave morphology. Our results confirm that the effects of zatebradine are relatively specific for the sinus node. These included: 1) prolongation of resting sinus cycle length; 2) enhanced suppression of automaticity after overdrive pacing; 3) prolongation of SACT; and 4) induction of sinus node pacemaker shifts. This agent should be used cautiously in patients with possible sinus node dysfunction.

Animals↗

PubMed1997

Vagal and sympathetic denervation in the development of oleic acid-induced pulmonary edema.

This study investigates the effects of autonomic denervation on extravascular lung water, pulmonary hemodynamics, the filtration coefficient of pulmonary vasculature and oxygenation in the development of pulmonary edema. Thirty seven dogs were divided into seven groups. No experimental treatment was conducted in group Nc (n = 4, sham operation) or group Nv (n = 6, bilateral vagotomy) during a 3 h observation period. In the following groups, oleic acid (0.06 ml/kg) was injected into a central vein to induce pulmonary edema: group OAc (n = 6, intact innervation); group OAv (n = 6, bilateral vagotomy); group OAa (n = 6, alpha-blockade by phentolamine); group OAs (n = 6, alpha- and beta-blockade by sympathectomy); and group OAvs (n = 3, vagosympathectomy). The results showed that in the dogs with normal lungs, bilateral vagotomy per se did not cause lung injury during 3 h of observation. However, in oleic acid pulmonary edema, vagotomy significantly deteriorated pulmonary edema by increasing pulmonary intravascular pressures; Alpha- or alpha- and beta- sympathetic inhibition deteriorated pulmonary edema by increasing pulmonary microvascular permeability. The severity of oleic acid-induced pulmonary edema was same in the dogs with vagosympathectomy as in the dogs with intact innervation. These results suggest the inhibition of vagal or sympathetic innervation will aggravate pulmonary edema in the dog.

Animals↗

PubMed2002

Diabetic gastroparesis in association with autonomic neuropathy and microvasculopathy.

Gastroparesis is a frequent and sometimes life-threatening complication of diabetes mellitus. Autonomic neuropathy seems to be one of the most important mechanisms underlying this entity, together with the other probable pathologies. The present study was performed in order to identify an alternative to gastric scintigraphy as a screening test. The gastric emptying times of 60 subjects (Group 1: 20 insulin-dependent patients, Group 2: 20 non-insulin-dependent diabetes mellitus patients, and Group 3: 20 healthy volunteers) were monitored by gastric scintigraphy. Perception thresholds for cold, heat, and vibration were tested by a quantitative sensory test, and QTc dispersions were calculated from standard electrocardiography recordings. In addition, fasting blood glucose, hemoglobin A1c and urine beta2-microglobulin and microalbumin concentrations were determined for the patient groups. Funduscopic examination was performed by an independent ophthalmologist. Gastroparesis was determined in both patient groups, regardless of fasting blood glucose and hemoglobin A1c concentrations. A strong correlation was observed between nephropathy, retinopathy, and cardiac autonomic denervation (QTc) and gastroparesis. In conclusion, retinal and renal microvasculopathy parameters and cardiac autonomic function tests may be useful for screening diabetic patients for gastroparesis.

Adult↗

PubMed1996

QT interval and dispersion in primary autonomic failure.

OBJECTIVE: To investigate the role of the autonomic nervous system in determining QT interval and dispersion. PATIENTS AND METHODS: 32 patients with chronic primary (idiopathic) autonomic failure (19 men, mean age 60 years) and 21 normal controls (11 men, mean age 59) without symptoms of ischaemic heart disease were studied retrospectively. Autonomic failure was diagnosed by a combination of symptomatic postural hypotension, subnormal plasma noradrenaline response to head-up tilt, and abnormal cardiovascular responses to standing, Valsalva manoeuvre, mental stress, cutaneous cold, isometric exercise, and deep breathing. QT intervals were measured from surface electrocardiograms and QT dispersion was defined as maximum QT--minimum QT occurring in any of the 12 leads. RESULTS: Mean heart rate (RR intervals) was similar in patients with autonomic failure and controls (S2 lead: 865 (132) v 857 (108) ms, P = NS; V2 lead: 865 (130) v 868 (113) ms, P = NS). QT intervals measured from electrocardiogram leads S2 and V2 were significantly longer in patients than in controls (401 (40) v 376 (16) ms, P < 0.01; and 403 (41) v 381 (20) ms, P < 0.05 respectively). The mean maximum QT interval in any lead, which is the best estimate of the maximum duration of electrical systole, was significantly longer in the patients than in controls (417 (48) v 388 (23) ms, P < 0.005). Linear regression analysis of QT and RR intervals for both groups showed a significant difference between the slopes of the two regression lines (F = 8.4, P < 0.001). However, QT dispersions were similar between patients and controls. CONCLUSIONS: Patients with primary autonomic failure have prolongation of QT intervals, indicating that the autonomic nervous system is an important determinant of QT interval. However, QT dispersion does not seem to be affected by chronic primary autonomic denervation.

Autonomic Nervous System Diseases↗

PubMed2001

Electrocardiographic changes during postnatal development in conscious swine with cardiac autonomic imbalance.

Using a conscious swine model, we studied the effects of different patterns of cardiac autonomic denervation on alterations of R-R and Q T intervals for 8 postnatal weeks. Newborn pigs were assigned randomly to four different groups: sham-operated controls (C), stellate ganglion ablation (SGX), either left (LSGX) or right (RSGX), and the right cardiac vagus nerve (RCVX) transection. The ECGs were recorded by telemetry while animals rested quietly or were judged behaviorally to be asleep. Analyses of the ECG included measurements of R-R and Q-T intervals, as well as corrected Q-T intervals (QTc). Poincaré plots were used to display age-related differences in R-R and Q-T intervals. For stellectomized animals, significantly prolonged R-R intervals were first observed at post-surgical week 3 in the RSGX group and at week 5 in the LSGX group. Significantly prolonged QTc was found only in the RSGX group. In the RCVX group, shortened QTc and R-R intervals were noted at 6 and 7 weeks after denervation. Furthermore, three of six RSGX animals (50%) and one of four RCVX animals (25%) exhibited marked pauses in sinus rhythm that were unrelated to changes in heart rate or to sinus arrhythmia. These results in conscious animals support our hypothesis that abnormal autonomic innervation of the heart during maturation, e.g., withdrawal of vagal cardiac modulation or asymmetry of sympathetic innervation, impairs cardiac electrical stability.

Aging↗

PubMed1988

Ocular autonomic function in progressive autonomic failure.

Ocular autonomic function was assessed in 4 patients with progressive autonomic failure (PAF) and age-matched control subjects, by measurement of the pupil cycle time, and determination of autonomic denervation hypersensitivity of the iris. Pupil cycle time was abnormal in all patients with PAF; sustained pupil cycling was absent in 5 of the 8 eyes tested of the PAF patients, compared with only 16 eyes from 70 control subjects. Pupil constriction in response to 2.5% methacholine, indicative of parasympathetic denervation hypersensitivity, was significantly increased in patients with PAF (p less than 0.001), whilst pupil dilation in response to 0.5% phenylephrine, indicative of sympathetic denervation hypersensitivity, was also significantly higher in the PAF patients (p less than 0.001). The results suggest that ocular autonomic function may provide a sensitive early indicator of generalised autonomic dysfunction.

Aged↗

PubMedDate not supplied

Selective denervation of the autonomic nerve supply of the nasal mucosa.

The autonomic innervation of the nasal mucosa has been studied in normal rats and in rats in which the supplying nerves had seen selectively transected; postoperative survival times varied from 2 weeks up to 18 months. The vascular structures appeared to be innervated both by acetylcholinesterase- and noradrenalin-containing fibres. Furthermore a nerve plexus consisting of both types of fibres was observed in the subepithelial region. The nasal glands however showed only a cholinergic innervation. The pattern of the autonomic nerve supply deduced from these selective denervation experiments does not differ fundamentally from the generally accepted scheme of this system in the nose of other mammals. Denervation occurred within 2 weeks after transection of the supplying nerves, but after longer survival times reinnervation was observed.

Acetylcholinesterase↗

PubMed2003

Absence of clinical signs of cardiac denervation after percutaneous myocardial laser revascularization.

BACKGROUND: Percutaneous myocardial revascularization with laser (PMR) is a catheter-based technique that has generated much interest in the treatment of patients with severe coronary artery disease. Several mechanisms have been proposed to explain the reported clinical benefits of this technique. Cardiac autonomic denervation is among these. METHODS: We studied 32 consecutive patients with chronic severe angina not suitable for other revascularization approaches. Canadian Class Society (CCS) class clinical assessment, Naughton exercise stress test, and scintigraphic myocardial perfusion were evaluated before and 1 and 6 months after PMR. Ewing's autonomic tests, heart rate variability (HRV), and plasmatic catecholamines were assessed before revascularization in non-diabetic and diabetic patients and repeated 1 month after PMR in 13 non-diabetics. A psychological test was carried out before PMR to evaluate the attitude towards this new procedure. RESULTS: All the markers of autonomic cardiac control were unmodified after the procedure. Moreover, scintigraphic perfusion measured in the lasered areas was similar before and after the procedure. On the other hand, the clinical conditions significantly improved (CCS class from 3+/-0.8 to 1.9+/-0.9 at 1 month, P<0.01) and the exercise-related ischemic threshold was significantly better (from 311+/-28 to 453+/-51 s, P<0.05). The patients with a psychologically 'positive' expectation for this new procedure had results comparable to those with a 'negative' expectation. CONCLUSIONS: PMR improves symptoms in patients with end-stage coronary artery disease in the absence of any detectable clinical sign of heart denervation.

Aged↗

PubMed1995

Development of a swine animal model for the study of sudden infant death syndrome.

An animal model with selective cardiac autonomic denervation was developed in neonatal swine for the purpose of future studies concerning the possible role of abnormal cardiac innervation in the etiology of sudden infant death syndrome. Twenty-six 4- to 8-day old piglets were randomly assigned to one of the following treatment groups: right stellate ganglionectomy (RSG), left stellate ganglionectomy (LSG), right cardiac vagotomy (RCV), and sham-operated control group. Piglets were anesthetized with Saffan and mechanically ventilated on room air. The thoracic wall was opened, and the sternum was divided, permitting exposure of pleura, heart, and lungs. After completion of one of these operative procedures, the thoracic wall was closed in layers. On successful recovery from anesthesia and extubation, piglets were returned to their sows. Postoperative administration of antibiotics was performed during the first week. Electrocardiograms were recorded once a week over an 8-week period. The sham-operated control group had a postnatal increase in QTc and decrease in heart rate. The RSG group had significantly longer QTc than the sham-operated control group QTc, whereas the RCV group had significantly shorter QTc interval than sham-operated controls. Surgical complications caused the death of two piglets (hemorrhage in one and aspiration in the other), infection caused the death of one piglet 2 weeks after surgery, and three died of unknown causes (one from the RSG group and two from the RCV group). The cause of death for these three animals could not be determined (necropsy was not revealing) because they were not monitored at the time of their demise.(ABSTRACT TRUNCATED AT 250 WORDS)

Alfaxalone Alfadolone Mixture↗

PubMed1984

Supersensitivity of the rabbit iris sphincter muscle induced by trigeminal denervation: the role of substance P.

The rabbit left ophthalmic nerve (first branch of the left trigeminal nerve) was cut at the intracranial, peripheral side of the trigeminal ganglion and the effects of denervation were examined using iris sphincter muscle preparations isolated from the left and right eye, as denervated and control innervated preparations, respectively. Electrical transmural stimulation produced a substance P-operated contraction, in addition to a cholinergic one, in the preparation isolated from the right control eye. The former response was abolished in the preparation isolated from the left denervated eye, thereby indicating that the trigeminal, substance P nerve ipsilaterally innervates the iris sphincter muscle. Exogenously applied carbachol and substance P produced concentration-dependent contractions in preparations isolated from either eye. Supersensitivity characterized by a decrease in median effective concentration (EC50) values and an increase in maximal response was observed in the responses to both agents of the left denervated preparation. Such supersensitivity developed slowly after trigeminal denervation and 3 weeks was required for full development. Exogenously applied KCl produced substance P-operated and direct muscle contractions in the right control preparations. In the left denervated preparations, the substance P-operated contraction was either markedly attenuated or abolished, while the direct muscle-related contraction was enhanced after trigeminal denervation. The length of the left denervated preparation was longer than that of the right control preparation, and the resting tensions required to produce maximal carbachol contraction shifted to lower values. These physical changes of the iris sphincter muscle developed within 5 days after trigeminal denervation. In the non-denervated preparation treated with capsaicin in vitro, electrical transmural stimulation and KCl failed to produce the substance P-related contraction. However, supersensitivity to neither exogenously applied substance P, carbachol and KCl nor physical changes were observed in the capsaicin-treated preparation. These results suggest that trigeminal, substance P-related nerves tonically and ipsilaterally innervate the rabbit iris sphincter muscle and that the denervation results in non-specific supersensitivity. These findings are essentially the same as those observed in various types of smooth muscles after autonomic denervation.

Action Potentials↗

PubMed2004

Is PA-PWRmax truly a preload-independent index of myocardial contractility in anesthetized humans?

This study tested the hypothesis that the preload-adjusted maximal power index (PA-PWRmax) is a load-independent index of human myocardial contractility. Based on the ventricular pressure-volume relationship and derived from stroke work, the index is the product of instantaneous ventricular pressure and volume changes, divided by a correction term of end-diastolic volume (EDV2) or end-diastolic area (EDA3/2) to adjust for preload effects. Echocardiographic measures of instantaneous ventricular area change may be used to obtain PA-PWRmax noninvasively. We prospectively evaluated 28 human subjects undergoing cardiac evacuation before cardiopulmonary bypass procedures. Continuous peripheral arterial pressure, pulmonary arterial pressure, and echocardiographic views of the left ventricle in the transgastric short-axis view were recorded. Simultaneously gated instantaneous fractional shortening (FS) and PA-PWRmax indices were calculated, with FS = (EDA - ESA)/EDA and PA-PWRmax = [MAP (EDA - ESA)]/ EDA3/2, where ESA = end-systolic area and MAP = instantaneous mean arterial pressure. FS decreased uniformly with cardiac evacuation and decreasing pulmonary artery diastolic pressure (t = -5.4; 95% confidence interval, -10 to -0.046; p < 0.001), as did PA-PWRmax (t = -5.8; 95% confidence interval, -2.25 to -1.08; p < 0.001). FS and PA-PWRmax showed a strong downward correlation (r = 0.81). Unlike previous studies of autonomically denervated animals, our study did not find PA-PWRmax to be preload independent, perhaps because of the instantaneous homeostatic mechanisms of the human autonomic nervous system linking contractility to loading conditions.

Anesthesia, General↗