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Biomedical subjects

C J Porter

Publications and source records attributed to C J Porter.

At least 91 records · Page 5Linked to original sources
PubMed1987

Identification and confirmation of arsenobetaine and arsenocholine in fish, lobster and shrimp by a combination of fast atom bombardment and tandem mass spectrometry.

Using fast atom bombardment (FAB) ionization combined with tandem mass spectrometry (MS/MS), the identity of arsenobetaine (AB) in extracts of sole, haddock, lobster and shrimp was unequivocally confirmed. Evidence was also presented for the presence of arsenocholine (AC) in the shrimp extract. Confirmation was obtained by comparing the collision-induced dissociation (CID) daughter ion and parent ion spectra of major ions in the FAB spectra from these extracts with those from the authentic standards.

Animals↗
PubMed1987

Intermediate follow-up and predicted survival after the modified Fontan procedure for tricuspid atresia and double-inlet ventricle.

We reviewed the records of 135 patients with tricuspid atresia and 120 patients with double-inlet ventricle who underwent modified Fontan procedure from 1973 to June 1985. This represents 67% of the total number of patients undergoing the procedure during this period. There were 32 (12%) in-hospital deaths (14 tricuspid atresia, 18 double-inlet ventricle) and 23 late deaths (13 tricuspid atresia, 10 double-inlet ventricle). For patients surviving to hospital dismissal, the 5 year survival was 87%. Follow-up data (mean 3.9 years) were obtained for 157 patients who survived at least 1 year after operation. At last follow-up, of the 157 patients, 92% were in NYHA class I or II, 92% claimed to be improved clinically by the operation, and 98% could work or attend school. Fifty percent were not taking medication at last follow-up. Some degree of edema or ascites was found in 16%. The study showed that (1) the modified Fontan procedure can be performed with low in-hospital mortality (12%) in patients with tricuspid atresia and double-inlet ventricle, (2) hospital survivors have an estimated 5 year survival of 87%, (3) subjectively, functional status is good for hospital survivors at intermediate follow-up, and (4) fluid retention continues to be a problem in a minority (16%) of patients.

Blood Vessel Prosthesis↗
PubMed1986

Progressive atrioventricular block during exercise in univentricular heart.

Two patients who had univentricular heart presented with complaints of recurrent nausea and vomiting during exertion. Exercise study revealed 1:1 atrioventricular conduction and no symptoms at rest; at peak exercise, both patients experienced progressive, high grade, second degree atrioventricular block and nausea. Both patients underwent permanent pacemaker implantation, with relief of symptoms. Exercise testing is important in evaluating patients who are at increased risk of spontaneous atrioventricular block, and exertion-induced nausea may be a clue to its presence.

Child↗
PubMed1985

Exercise testing in children with Wolff-Parkinson-White syndrome.

Exercise testing using a modified Bruce treadmill protocol was performed by 17 children with Wolff-Parkinson-White (WPW) syndrome. All had intracardiac electrophysiology studies as well. Endurance time, heart rate and blood pressure were normal during exercise. Ventricular premature complexes were seen with exercise in 2 patients and supraventricular tachycardia with exercise testing was seen in 2. Disappearance of the delta wave with exercise correlated with a long anterograde effective refractory period of the Kent bundle (360 to 390 ms). Children with partial normalization of the QRS during exercise had a longer anterograde effective refractory period of the Kent bundle than those in whom preexcitation persisted. In 1 patient, disappearance of the delta wave with exercise confirmed the diagnosis of WPW syndrome. Preexcitation was seen only after exercise in 1 patient. Exercise testing is of value in the evaluation of children with WPW syndrome; children with WPW syndrome who have total normalization of the QRS interval during exercise and few or no symptoms of tachycardia do not require electrophysiologic study.

Adolescent↗
PubMed1985

Trace analysis by gas chromatography/mass spectrometry (GC/MS) using a tandem double-focusing/quadrupole instrument.

Analysis for oestradiol bis-tert-butyldimethylsilyl ether by gas chromatography/mass spectrometry (GC/MS) with selected reaction monitoring ([M]+.----[M-C4H9]+) using a tandem double-focusing/quadrupole instrument gave a detection limit below 10 pg. During analyses of a plasma extract, the selectivity of detection was superior to conventional selected ion monitoring. A parent ion resolution of 5000 was used to eliminate detection of all components but the chosen analyte.

Estradiol↗
PubMed1985

Atrial flutter in the young: a collaborative study of 380 cases.

As children with cardiac disease grow older, atrial flutter becomes more prevalent. A collaborative study was performed in 19 institutions to determine the clinical characteristics of these children and the factors affecting prognosis. There were 380 patients with one or more electrocardiographically documented episodes of atrial flutter that first occurred between ages 1 and 25 years (mean age at onset 10.3). Episodes of flutter continued to occur for a mean of 2.5 years after the onset. Of the 380 patients, 60% had repaired congenital heart disease, 13% palliated congenital heart disease, 8% unoperated congenital heart disease, 8% an otherwise normal heart, 6% cardiomyopathy, 4% rheumatic heart disease and 2% other lesions. Overall, drugs were effective in eliminating atrial flutter in 58% of patients; specifically, amiodarone and digoxin plus quinidine were effective in 53%, digoxin alone in 44% and propranolol in 21%. Amiodarone was effective in seven (78%) of nine patients. Corrective surgery was performed after the onset of atrial flutter in 66 patients; in 52% the atrial flutter was easier to control or it resolved and in only 4% it was worse. At follow-up (mean 6.5 years), 83% of the patients were alive (49% without atrial flutter and 34% with atrial flutter) and 17% died (10% suddenly, 6% of nonsudden cardiac cause and 1% of noncardiac cause). Cardiac death occurred in 20% of those for whom an effective drug could not be found to eliminate atrial flutter compared with 5% of those who were treated with an effective drug (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Flutter↗
PubMed1985

Permanent cardiac pacing after the Fontan procedure.

Permanent cardiac pacing after a Fontan procedure is complicated by complex cardiovascular anatomy. Of 332 patients undergoing the Fontan procedure at the Mayo Clinic, we evaluated 15 who postoperatively required permanent pacing (mean age 16.5 years, range 4 to 31 years). Underlying congenital cardiac defects included univentricular heart in nine patients, double-outlet right ventricle in three, and tricuspid atresia in three. The indication for pacing was postoperative heart block in seven patients, congenital heart block in five, postoperative sick sinus syndrome in two, and heart block because of previous operation in one. Pacemakers were implanted immediately postoperatively in 11 patients and 12 to 57 months later in four patients. VVI systems were used in nine patients, DDD in four, AAI in one, and a Medtronic Activitrax VVI in one. All ventricular leads were epicardial. Four atrial leads were transvenous endocardial and one was epicardial. Three patients died 4, 9, and 69 months later of causes unrelated to pacing. Among the 12 survivors, mean follow-up was 34 months (range 1 to 107 months). Two patients had a total of three episodes of loss of ventricular capture because of increased chronic thresholds. Our current approach to pacing after a Fontan procedure includes (1) intraoperative placement of temporary atrial and ventricular electrodes, (2) intraoperative attachment of a permanent ventricular epicardial lead for congenital or surgically induced high-grade atrioventricular block, (3) postoperative insertion of transvenous atrial leads if dual-chamber pacing is indicated, and (4) use of programmable pulse generators with high output capability.

Adolescent↗
PubMed1984

Antegrade conduction and AV node function in patients with unidirectional retrograde accessory pathways.

In 26 patients with unidirectional retrograde accessory pathways (URAP), antegrade conduction properties were evaluated. During electrophysiologic study the interval from the low septal right atrial potential to the His bundle potential (LSRA-H) in sinus rhythm (SR) was found to be less than 60 msec in 7 out of the 18 patients with left-sided URAP and in one out of two patients with septal URAP. Each of the six patients with right-sided URAP had an LSRA-H equal to or greater than 70 msec. During atrial extrastimulus testing, LSRA-H failed to prolong more than 100 msec (LSRA-H increment equal to or less than 100 msec) in four of six patients with left-sided URAP and LSRA-H of less than 60 msec in SR as well as in the one of two patients with septal URAP in whom the LSRA-H in SR was less than 60 msec. During rapid atrial pacing, we found 1:1 AV node conduction at a pacing rate of more than 200 bpm in the one patient with septal URAP and in 7 out of 14 patients with left-sided URAP who could be assessed. Three of these patients had progression from 1:1 AV conduction to 2:1 AV block without intervening Wenckebach. In conclusion, accelerated AV node conduction in SR and reduced AV node function during rapid atrial pacing or extrastimulus testing was found in 44% of our patients with left-sided or septal URAP. Since these patients are at higher risk for faster ventricular response to atrial flutter and fibrillation and for high frequency during supraventricular tachycardia, these findings were of clinical relevance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Amiodarone treatment of critical arrhythmias in children and young adults.

The majority of sudden cardiac deaths in children occur in patients with prior arrhythmias and an abnormal heart. Amiodarone was given to 39 young patients (35 with an abnormal heart) with arrhythmias unresponsive to conventional treatment. Their age ranged from 6 weeks to 30 years with nine patients younger than 2 years of age. Atrial flutter was present in 16 patients, ventricular tachycardia in 14 patients and supraventricular tachycardia in 9 patients. The most common diagnosis (14 patients) was postoperative repair of congenital heart disease. The dose ranged from 2.5 to 21.6 mg/kg per day (mean 8.2). Elimination of arrhythmia (on 24 hour electrocardiography) occurred in 15 of 16 patients with atrial flutter, 11 of 14 with ventricular tachycardia and 5 of 9 with supraventricular tachycardia. Symptomatic side effects were: rash (three patients), headache (two patients), nausea (one patient) and peripheral neuropathy (one patient); seven patients had asymptomatic corneal microdeposits which normalized in all after the drug was discontinued. No side effects occurred in patients younger than 10 years of age. The following changed with treatment (p less than 0.05): heart rate decreased (three patients with atrial flutter and sick sinus syndrome required pacemaker implantation for bradycardia) and QTc increased; thyroxine (T4) and serum reverse triiodothyronine (T3) increased. During follow-up study (range 6 months to 3 years), 21 of the 39 patients continued to take amiodarone with complete control of arrhythmias, 9 were no longer taking the drug and 9 died (7 nonsudden and 2 sudden deaths). Amiodarone is an extremely effective treatment for infants and children with tachyarrhythmias resistant to conventional treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Junctional automatic ectopic tachycardia: new proposed treatment by transcatheter His bundle ablation.

Three infants with junctional automatic ectopic tachycardia (JET) were seen over an 8-month period. Each had decreased left ventricular function. Two were treated with amiodarone, which together with propranolol reduced the tachycardia rate 10 to 40 bpm, but did not result in sinus rhythm. One patient died suddenly at home, as had 50% of our patients with JET treated with conventional medication. Two patients were treated by transcatheter ablation of the bundle of His and implantation of an atrial synchronous pacemaker. Neither has had subsequent tachycardia or required drugs. One patient resumed sinus rhythm and does not use his pacemaker. The other patient has complete AV block and continues to use her pacemaker. This aggressive approach to this lethal dysrhythmia offers hope for prevention of the former bad prognosis.

Amiodarone↗
PubMed1983

Pacemaker treatment of sick sinus syndrome in children.

The sick sinus syndrome is being recognized with increasing frequency in children. Although it is sometimes benign, it can be serious or have fatal consequences. Fifty-one patients (mean age 10.5 years) underwent permanent cardiac pacing for sick sinus syndrome. Twenty patients had epicardial ventricular pacing and 12 had an epicardial atrial implant. Seven had endocardial atrial pacing, six epicardial atrioventricular (AV) sequential pacing, four epicardial universal pacing and two endocardial universal pacing. Of the 49 symptomatic patients, 45 had relief of symptoms. Eleven of 18 patients with associated tachyarrhythmias had amelioration of their tachycardia. There were no early but two late deaths unrelated to the pacemakers. Seven patients during a mean follow-up period of 26 months required reoperation for pacing lead or sensing problems. Permanent pacing for sick sinus syndrome in children is a safe and symptomatically effective procedure.

Adolescent↗