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.

Changes in R-R and Q-T intervals following cardiac vagotomy in neonatal swine.

Asymmetric innervation of the myocardium, especially a predominance of sympathetic innervation, may establish conditions whereby electrical instability could result. Using a swine animal model, we studied the effect of right cardiac vagal denervation on the variability of R-R and Q-T intervals. Newborn pigs were assigned randomly to two groups: sham-operated controls (C), or denervation of the right cardiac vagus nerve (RCVX).

The area postrema of newborn swine is activated by hypercapnia: relevance to sudden infant death syndrome?

This study was performed to investigate a role of the neonatal area postrema (AP) in the chemoreceptor response to hypercapnia which is defective in sudden infant death syndrome (SIDS). AP responses to CO2 inhalation were monitored in 1 to 5 week old piglets by mapping neurons that were induced to express the c-fos gene product, Fos--a marker of functional activation. Interpretive confounds were minimized by controlling for hypoxia, the effects of surgical procedures and ambient environmental stressors on neuronal activity (c-fos expression).

Induction of c-fos gene expression by spinal cord transection in the rat.

Sympathetic nerve activity is maintained after high spinal injury through circuits that remain in question. We evaluated patterns of c-fos gene induction as a monitor of spinal neurons responding to high spinal cord transection in the rat. Rats were anesthetized with isofluorane.

Induction of c-fos gene expression by spinal cord transection in Sus scrofa.

Functional responses of primary sensory afferents and spinal cord were monitored in swine subjected to a high cervical (C1) spinal transection. Two and a half hours after transection, dorsal root ganglia and cervical and thoracolumbar spinal segments were processed immunocytochemically for the c-fos gene product, Fos and related antigens. In spinal-transected animals, Fos-like immunoreactivity (FLI) was induced in spinal laminae I, V, VII and X and the intermediolateral cell column but not in sensory ganglia as compared to controls: spinal-intact age-matched littermates.

Effects of cardiac autonomic imbalance on postnatal changes in the electrocardiographic Q-T interval in conscious swine.

The effects of partial autonomic denervation of the heart rate and Q--T interval were examined during maturation in swine. Four groups of newborns were prepared: right stellate ganglionectomy (RSG), left stellate ganglionectomy (LSG), right cardiac vagotomy (RCV) and sham-operated. Swine were studied postsurgically for eight weeks.

Anatomy of medullary and peripheral autonomic neurons innervating the neonatal porcine heart.

Gross and microscopic anatomical investigations were carried out in 14 piglets aged from 4 to 66 days. True Blue (7-50 microliters) and Diamidino Yellow (7-50 microliters) were injected individually into 2 different cardiac sites (the right atrial ganglionated plexus, the inferior vena cava, inferior atrial ganglionated plexus, the right atrium or the right ventricle). Gross anatomy: Globular superior cervical and nodose ganglia, elongated stellate ganglia, multiple small middle cervical ganglia and multiple small mediastinal ganglia along the course of cardiopulmonary nerves were identified.

Age-related effects of cardiac sympathetic denervation on the responses to cardiopulmonary receptor stimulation in piglets.

The effects of right stellate ganglionectomy (RSG) and bilateral stellate ganglionectomy (BSG) on cardiovascular responses to phenyl biguanide (PBG, 80 micrograms/kg) were studied in 1- and 8-wk-old piglets. Animals were anesthetized with Saffan, paralyzed, thoractomized, and ventilated with 100% O2. Recordings of the ECG (lead II) and aortic pressure (AoP) were used to compute the maximum R-R interval, heart rate (HR), and mean AoP, and to determine the occurrence of atrioventricular conduction block (AVB).

Hypotension-induced expression of the c-fos gene in the medulla oblongata of piglets.

Neural networks that mediate the reflex response to baroreceptor withdrawal were explored in Sus scrofa. Induction of c-fos was used as a monitor of synaptic activity in response to hypotension sustained by systemic administration of a peripheral vasodilator, sodium nitroprusside. Patterns of c-fos gene expression were compared between Saffan-anesthetized experimental animals and age-matched normotensive controls administered vehicle.

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.

Neuronal activity of the stellate ganglia in neonatal swine.

In anesthetized, paralyzed, and artificially ventilated neonatal pigs, neuronal activity was recorded extracellularly from the intact right stellate ganglion. Of 301 investigated neurons, only a few had spontaneous activity: 27 neurons generated activity either during lung inflation or deflation, and 1 neuron generated activity related to the cardiac cycle. The remaining 273 neurons were activated by stroking of body hair or by light pressure applied to various somatic sites.

Cardiac responses elicited by stimulation of loci within stellate ganglia of developing swine.

Stimulation with bipolar electrodes of specific loci in stellate ganglia elicited in anesthetized piglets, 1-4 weeks of age, alterations in cardiac function and aortic pressure. Responses were also elicited by chemical stimulation in specific loci of these ganglia. The probability of eliciting a cardiovascular response by stimulating loci in a stellate ganglion increased with increasing postnatal age.

Chest pain in adolescents.

Adolescents with chest pain were compared with healthy adolescents to determine if they were more likely to believe they had cardiac disease and were less healthy than their peers. Perceptions were examined with a questionnaire and results analyzed by chi 2 analysis. Twenty-two percent of adolescents with chest pain were diagnosed with cardiac problems, a prevalence rate higher than previous reports.

Effects of elevated plasma magnesium concentration on cerebrospinal fluid levels of magnesium in neonatal swine.

To determine whether magnesium (Mg) can cross the blood brain barrier in developing swine, simultaneous measurements of [Mg] in plasma and cerebrospinal fluid (CSF) were made during experimental elevation of plasma [Mg] in 12 swine of differing postnatal age. All were anesthetized with Saffan and maintained at normal arterial blood gas composition. Aortic pressure and heart rate were monitored.

Effects of acute hypoxemia on responses to dopamine and dobutamine in neonatal swine.

The effects of acute hypoxemia on cardiovascular responses to dopamine (DA) and dobutamine (DB) were studied in 2-4 day (n = 21) and 13-17 day (n = 27) old swine under sodium pentobarbital anesthesia. Sequential 10-min infusions of 2, 5 and 15 mu/kg/min of DA or DB or normal saline were administered under conditions of normoxemia and repeated during hypoxemia. Data are presented as mean percent of baseline value +/- SE.

Unusual observations on hypermagnesemic levels and cardiorespiratory effects in neonatal swine.

Mg is being used as a therapeutic agent in different clinical conditions, i.e. preeclampsia or eclampsia, and as a tocolytic agent to prevent premature delivery.

Increasing extracellular calcium concentration does not prevent hypotensive effects of verapamil in neonatal swine.

Effects of CaCl2 on cardiac function and regional circulatory responses to verapamil (V) infusion were studied in pentobarbital-anesthetized 2-week-old swine. V 100 micrograms/kg (n = 15) or 300 micrograms/kg (n = 15), given as a 2-min intravenous infusion, was repeated after 30 min. Only V was given to 15 of these.

Comparative effects of bicarbonate and dichloroacetate in newborn swine with hypoxic lactic acidosis.

Unlabelled: Sodium bicarbonate (BC) and dichloroacetate (DCA) were studied in 7- to 14-day-old (n = 25) anesthetized swine with hypoxic acidosis. BC (base deficit X kg X 0.3, n = 10), DCA (300 mg/kg, n = 7) or saline (n = 8) was infused for 1 h.

Young long distance runners. Physiological and psychological characteristics.

This study presents the physiological and psychological characteristics and the running histories of 16 subjects who began long distance running at age 4-12 years. Running duration was 3-15 years (mean 8.4 +/- 3.

Use of demand pacemaker in children with Guillain-Barré syndrome and cardiac arrhythmias.

We report 2 patients with Guillain-Barré syndrome who exhibited autonomic dysfunction, including lability of blood pressure and heart rate, frequent episodes of profound bradycardia, and occasional asystole. Both patients required insertion of a temporary venous pacemaker which was activated a few times during the following days. The potential need for ventilatory support in patients with Guillain-Barré syndrome is well known; however, death in these patients due to acute cardiovascular failure during autonomic dysfunction continues to occur.

Bilateral origin of the left anterior descending coronary artery in a young man.

Abnormalities of coronary artery origin from the aorta have been implicated in sudden death in sports among young athletes. We describe an 18-year-old patient who presented with nonspecific chest pain, developed ventricular couplets during recovery from a stress test, and whose coronary angiograms revealed bilateral left anterior descending coronary arteries, an abnormality that has not been previously reported.

Chest pain, dyspnea on exertion, and exercise induced asthma in children and adolescents.

Unlabelled: The contribution of maximal exercise tests to the evaluation of 180 patients with chest pain associated with exercise (n = 147) or dyspnea on exertion (DOE, n = 33) was examined. The ages ranged from 5 to 22 (mean 13.2) years, and 68 patients were females.