Ventricular pacemaker upgrade: experience, complications and recommendations

OBJECTIVE

To assess outcomes of pacemaker upgrade from single chamber ventricular to dual chamber.

DESIGN

Retrospective analysis of patients undergoing the procedure.

SETTING

Specialist cardiothoracic unit.

PATIENTS

44 patients (15 female, 29 male), mean (SD) age at upgrade 68.2 (12.9) years.

INTERVENTIONS

Upgrade of single chamber ventricular to dual chamber pacemaker.

MAIN OUTCOME MEASURES

Procedure duration and complications.

RESULTS

Principal indications for upgrade were pacemaker syndrome (17), "opportunistic"--that is, at elective generator replacement (8), heart failure (7), non-specific breathlessness/fatigue (7), and neurally mediated syncope (3). Mean (SD) upgrade procedure duration (82.9 (32.6) minutes) significantly exceeded mean VVI implantation duration (42.9 (13.3) minutes) and mean DDD implantation duration (56.6 (22.7) minutes) (both p < 0.01). Complications included pneumothorax (1), ventricular arrhythmia requiring cardioversion (2), protracted procedure (10), atrial lead repositioning within six weeks (8), haematoma evacuation (1), superficial infection (1), and admission to hospital with chest pain (1); 20 patients (45%) suffered one or more complications including four of the eight who underwent opportunistic upgrade.

CONCLUSIONS

Pacemaker upgrade takes longer and has a higher complication rate than either single or dual chamber pacemaker implantation. This suggests that the procedure should be performed by an experienced operator, and should be undertaken only if a firm indication exists. Patients with atrial activity should not be offered single chamber ventricular systems in the belief that the unit can be upgraded later if necessary at minimal risk.

Comparison of radial versus brachial approaches for diagnostic coronary angiography when the femoral approach is contraindicated

One hundred patients with contraindications to the femoral approach were randomized to undergo diagnostic coronary angiography via percutaneous radial puncture or brachial artery cutdown. Procedure duration, fluoroscopy time, and total radiation dose were significantly less via the radial route, whereas procedural success, complication rates, and pain scores were comparable; we conclude that the radial technique should be the arm approach of choice for new trainees, although there will be occasions when radial access fails and a brachial approach is required.

Genetic and physical mapping of the McKusick-Kaufman syndrome

McKusick-Kaufman syndrome is a human developmental anomaly syndrome comprising mesoaxial or postaxial polydactyly, congenital heart disease and hydrometrocolpos. This syndrome is diagnosed most frequently in the Old Order Amish population and is inherited in an autosomal recessive pattern with reduced penetrance and variable expressivity. Homozygosity mapping and linkage analyses were conducted using two pedigrees derived from a larger pedigree published in 1978. The PedHunter software query system was used on the Amish Genealogy Database to correct the previous pedigree, derive a minimal pedigree connecting those affected sibships that are in the database and determine the most recent common ancestors of the affected persons. Whole genome short tandem repeat polymorphism (STRP) screening showed homozygosity in 20p12, between D20S162 and D20S894 , an area that includes the Alagille syndrome critical region. The peak two-point LOD score was 3.33, and the peak three-point LOD score was 5.21. The physical map of this region has been defined, and additional polymorphic markers have been isolated. The region includes several genes and expressed sequence tags (ESTs), including the jagged1 gene that recently has been shown to be haploinsufficient in the Alagille syndrome. Sequencing of jagged1 in two unrelated individuals affected with McKusick-Kaufman syndrome has not revealed any disease-causing mutations.

Exercise electrocardiogram and single vessel coronary artery disease

The aim of this study was to assess the efficiency of exercise tests in identifying ischaemia in the territories supplied by the three main coronary arteries. We prospectively analysed 578 patients with single vessel coronary disease (> 50% stenosis in one vessel and completely normal other vessels). Patients with single vessel coronary artery disease were divided into three groups: patients with significant left anterior coronary artery disease (group 1, n = 234); patients with significant right coronary artery disease (group 2, n = 201); patients with significant left circumflex disease (group 3, n = 143). Our study, which is the largest prospective study of patients with angiographically documented single vessel coronary artery disease, suggests that the exercise electrocardiogram is a poor predictor of circumflex coronary artery ischaemia. In addition, the site of ST depression identified from the electrocardiogram was a poor predictor of the site of myocardial ischaemia. No single lead could distinguish between the three groups and the location of coronary stenosis could not be predicted by location of ST depression.

Capture-S, a nontreponemal solid-phase erythrocyte adherence assay for serological detection of syphilis

A solid-phase erythrocyte adherence assay has been developed for the serological detection of reagin antibodies in syphilis. Capture-S (Immucor, Inc., Norcross, Ga.) is a nontreponemal, qualitative screening test for the detection of immunoglobulin G (IgG) and IgM antilipid antibodies in serum or plasma samples from blood donors. The Capture-S assay utilizes a modified Venereal Disease Research Laboratory antigen bound to microtitration wells and anti-IgG- plus anti-IgM-coated indicator erythrocytes as the detection system. The Capture-S assay was evaluated at six separate sites on 10,942 specimens. For patient samples of clinically diagnosed syphilis categories (n = 366), the Capture-S assay yielded a sensitivity of 80.7% versus 80.3% for the rapid plasma reagin (RPR) card test (Becton Dickinson Microbiology Systems, Cockeysville, Md.). In comparative experiments on patient and donor samples (n = 10,222), the Capture-S assay demonstrated a sensitivity of 94% compared to 91.2% for the RPR card test. The Capture-S and RPR card tests produced essentially equivalent specificities of 99.2% and 99.3%, respectively, for this sample population. For five test sites, the Capture-S and RPR card test demonstrated a 98.3% agreement (10,085 of 10,264) of test results. These evaluations indicate that the Capture-S compares favorably to the RPR card test in assay sensitivity and specificity, with the added benefits of ease of use, accommodation of high-volume testing, and potential for automation.

Perceived discomfort associated with working with persons with varying disabilities

Perceptions of discomfort by nondisabled coworkers are a major barrier to the acceptance of disabled persons into work groups. This research examined whether reported discomfort varied by the type or nature of the disability. 151 subjects rated 20 types of disabilities in terms of how uncomfortable or comfortable they would be working closely at a nonspecified task with a person with the particular disability. A stable hierarchy of the 20 disabilities was found. Patterns and implications are discussed. Gender of the rater influenced the ratings, specifically females exhibited less discomfort with disabilities over-all than did males. Prior contact with a disabled person, either personally or at unspecified work, did not affect the ratings of discomfort.

Trimeresurus venom inhibition of anti-HPA-1a and anti-HPA-1b antibody binding to human platelets

A solid-phase red cell adherence assay was used to demonstrate the specific inhibitory effect of seven species of Trimeresurus snake venom on the binding of HPA-1a- and HPA-1b-specific platelet antibodies. Trimeresurus venom did not inhibit the binding of HLA-, HPA-3a-, HPA-3b-, HPA-4a-, HPA-5a-, and HPA-5b-specific platelet antibodies. Venom from other genera of snakes, including representatives from Agkistrodon, Ancistrodon, Bitis, Bothrops, Bungarus, Causus, Crotalus, Dendroaspis, Ecis, Micrurus, Naja, Notechis, Ophiophagus, Pseudechis, Sepedon (Hemachatus), and Vipera, all failed to specifically inhibit anti-HPA-1a and HPA-1b binding. These results may indicate that the component in Trimeresurus snake venom previously reported to bind to the platelet GPIIb-IIIa complex, inhibiting fibrinogen binding, binds close to the HPA-1a and HPA-1b epitopes.

The health maintenance organization: guilty of complacency

This critique indicts the health maintenance organization (HMO) for failure to respond to its most basic marketplace, partnership, and business obligations. Management competence is to blame; selective contracting, product development, and standardized practice patterns are nonexistent. It will be difficult for this HMO to become appropriately focused and action oriented rapidly.

Early complications after dual chamber versus single chamber pacemaker implantation

This study was performed to compare the frequency of early complications after single chamber versus dual chamber permanent pacemaker implantation. Early complication was defined as one occurring in the 6-week period following implantation. We prospectively analyzed consecutive pacemaker implantation from January 1987 to June 1993 at our regional center. All complications were also analyzed for the relationship to operator experience, the venous access route, and the presence of temporary pacing wire at the time of implantation of the permanent pacing system. A total of 2019 new pacemaker units were implanted during this period. 1733 patients (85.8%) received a VVI pacemaker and 286 (14.2%) a DDD unit. Wound infection occurred in 11 (0.6%) VVI patients and 6 (2.1%) DDD patients. Lead displacement occurred in 18 (1%) VVI patients and 15 (5.2%) DDD patients (11 [3.8%] atrial and 4 [1.4%] ventricular). There were 10 (0.6%) pneumothoraces, 9 (0.5%) hematomas requiring drainage, 1 (0.06%) chylocele, and 2 (0.1%) deaths in the VVI group. There were 2 (0.7%) pneumothoraces, 2 (0.7%) hematomas, and no deaths in the DDD group. There was no significant increase in complications for experienced infrequent implanters (< 12 systems per year). In both groups the subclavian approach was associated with a risk of pneumothorax when compared to the cephalic approach. The rate of wound infection was higher in patients who had a temporary pacing wire in place. The use of prophylactic antibiotics does not appear to affect the incidence of wound infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Complete hepatic venous isolation and extracorporeal chemofiltration as treatment for human hepatocellular carcinoma: a phase I study

BACKGROUND

We performed a phase I study of a novel system of complete hepatic venous isolation and extracorporeal chemofiltration in patients with unresectable hepatocellular carcinoma (HCC) to determine (a) whether systemic exposure to doxorubicin could be limited after high-dose hepatic arterial infusion (HAI), and (b) the hepatic maximum tolerated dose (MTD) of doxorubicin.

METHODS

Ten patients with biopsy-proven HCC were treated with 20-min HAI of doxorubicin (17 total treatments). Two patients were treated with doxorubicin 60 mg/m2, three patients were treated at 90 mg/m2, and five patients received 120 mg/m2. A newly developed dual-balloon vena cava catheter was advanced from the femoral vein, and the balloons were inflated to isolate and capture total hepatic venous outflow. The hepatic venous blood was pumped through extracorporeal carbon chemofilters before return of the blood to the systemic circulation.

RESULTS

Peak systemic doxorubicin levels were an average 85.6% lower than were peak prefilter levels (p < 0.01). Because all catheters were placed percutaneously and because the chemofiltration markedly limited systemic chemotherapy exposure, patients were discharged 1 day after 16 of the 17 treatments. The hepatic and systemic MTD of doxorubicin in this treatment protocol was 120 mg/m2.

CONCLUSIONS

This novel system of complete hepatic venous isolation and chemofiltration limits systemic chemotherapy toxicity and will allow use of higher doses of chemotherapeutic agents to treat HCC.

Increased doxorubicin levels in hepatic tumors with reduced systemic drug exposure achieved with complete hepatic venous isolation and extracorporeal chemofiltration

We evaluated a novel system of complete hepatic venous isolation and chemofiltration (CHVI-CF) to reduce systemic drug exposure following regional hepatic infusion of doxorubicin. Rabbits bearing hepatic VX-2 tumors were given doxorubicin via either hepatic arterial infusion (HAI) or portal venous infusion (PVI). A dual-balloon vena cava catheter and extracorporeal chemofilter were used to capture and filter hepatic venous blood in experimental animals. Control animals received chemotherapy without hepatic venous isolation and chemofiltration. Following a 5-min HAI of doxorubicin (3 or 5 mg/kg), control and experimental animals had similar doxorubicin levels in their livers and VX-2 tumors, but experimental animals showed a significant reduction in doxorubicin levels in systemic plasma, heart, and kidney tissue as compared with control animals (P < 0.01). HAI produced a 4-fold increase in doxorubicin levels in VX-2 tumors as compared with the drug levels obtained using PVI (P < 0.01). A single HAI of 3 mg/kg doxorubicin in animals treated with CHVI-CF produced marked tumor necrosis at 7 and 14 days after treatment. By increasing the total body clearance of doxorubicin, this system will allow HAI of higher doses of drug in attempts to improve the antitumor response.

Hemodynamic evaluation of the Monostrut and spherical disc Björk-Shiley aortic valve prosthesis with Doppler echocardiography

A Doppler echocardiographic study was performed to assess whether the Monostrut model of the Björk-Shiley valve (Shiley, Inc., Irvine, Calif.) had an improved hemodynamic performance in comparison with the spherical disc model in the aortic position. Twenty retrospectively randomly selected patients were studied, 10 with each valve type. Within each valve type two sizes of valve were studied, 21 and 23 mm. The two groups were comparable with respect to age, postoperative time, fractional shortening, New York Heart Association functional class preoperatively, and body surface area. Pulsed and continuous wave Doppler measurements were recorded at rest. Continuous wave Doppler recordings were performed every 2 minutes after exercise with supine bicycle ergometry until 10 minutes after exercise. Peak and mean gradients across the aortic valve prostheses were estimated. Both groups achieved a significant and comparable rise in heart rate with exercise. The mean gradients +/- standard error of the mean at rest and 2 minutes after exercise were 19.7 +/- 1.9 mm Hg and 30.9 +/- 2.2 mm Hg, respectively in the spherical disc group compared with 14.9 +/- 1.1 mm Hg and 23.6 +/- 1.7 mm Hg in the Monostrut group (p < 0.05 and p < 0.025, respectively). Peak transvalvular gradient at rest was 30.7 +/- 2.7 mm Hg in the spherical group compared with 23.9 +/- 1.9 mm Hg in the Monostrut group (p < 0.05). We conclude that the Monostrut Björk-Shiley valve prosthesis has better hemodynamic performance than the spherical disc model in the aortic position.

Measurement of regional left ventricular function using labelled magnetic resonance imaging

A technique for assessing regional left ventricular function using magnetic resonance imaging is described. Spatial modulation of magnetization (SPAMM) is effected immediately before images are obtained at various intervals during the cardiac cycle using a modified field echo even rephasing technique (FEER). By performing such modulation in two planes, a grid pattern of labelling can be produced across the image. On the resulting labelled short axis images of the left ventricle, the systolic increase in thickness (thickening) and decrease in length (shortening) of different regions of myocardium can then be measured. The findings in five normal volunteers are presented. Radial shortening was twice as great in the endocardium (mean 20.4%, standard deviation (SD) 5.7) than in the epicardium (mean 10.2%, SD 5.5) and appears to offer more promise as a marker of regional function than simple thickening (mean 9.8%, SD 13.6).

Studies in copper status and atherosclerosis

Findings of this paper indicate that leucocyte copper has a significant link with the level of atherosclerosis found within the groups studied. Therefore copper may be involved in the mechanisms associated with ischaemic heart disease (IHD).

Red cell antibody identification by solid phase red cell adherence utilizing dried RBC monolayers

Recent technological advances in the immobilization and drying of red cell monolayers for use in solid phase red cell adherence (SPRCA) assays have resulted in the development of reagent red cells for antibody screening and identification that are stable at mom temperature. Panels consisting of twelve different RBC samples dried onto individual microplate wells were evaluated with 176 samples whose antibody specificities had previously been determined by conventional hemagglutination techniques. Identification tests performed with dried SPRCA panels proved to be more sensitive and less time consuming than hemagglutination tests. The red cell antigens of dried membranes were shown to be stable and reactive following storage for 120 days at mom temperature.

The multislice cylinder: a new approach to quantification of cardiac single photon emission tomography

A new method of displaying SPECT (single photon emission tomography) thallium-201 images is described in which cardiac activity is constructed as a cylindrical map. Exercise thallium-201 scintigrams from 52 patients with known or suspected coronary artery disease are analysed by this technique and a simplified severity score devised.

A comparison of planar and tomographic thallium scintigraphy in patients with coronary artery disease

Planar and tomographic scans from 57 patients are compared and related to coronary arteriographic results. Tomography identified inferior and septal defects not seen on planar imaging. Planar imaging better identified apical defects. Lesions of the left circumflex were poorly defined by both techniques.

Radionuclide assessment of diastolic function in aortic regurgitation: a critical study of its measurement

Systolic and diastolic ventricular function was assessed in patients with aortic regurgitation as the peak ejection and filling rates. The measured rate of change of volume was related to the ejection fraction when expressed in end diastolic volumes per second (EDV.s-1) but not when expressed as stroke volumes per second (STV.s-1) suggesting that an apparent variation in left ventricular volume change when expressed as EDV.s-1 may occur as a result of an increase in end diastolic volume rather than any absolute alteration in filling rate. There was a significantly greater increase in peak filling than peak ejection rate with increasing heart rate in patients with aortic regurgitation, and this relation was exaggerated compared with that in controls. No definite difference in these indices of left ventricular function was found in patients with aortic regurgitation of severity varying from mild to severe. Isolated measurements of left ventricular filling rate may not accurately reflect left ventricular compliance since other factors, particularly heart rate, must be considered.

Radionuclide evaluation of aortic regurgitation: assessment of ventricular function by Fourier phase analysis

Forty patients with chronic isolated aortic regurgitation were studied by phase analysis of equilibrium radionuclide ventriculography to see whether this technique could detect changes in left ventricular (LV) function before the onset of symptoms. This technique was compared to the radionuclide ejection fraction and echocardiography. The severity of LV volume overload was assessed using the radionuclide regurgitant index. Patients with clinically severe aortic regurgitation had severe volume overload (high regurgitation index), increased echocardiographic left ventricular dimensions and significantly increased phase spread (loss of synchrony of wall motion) compared to mild and moderate groups. All but one had well maintained global left ventricular function assessed by the ejection fraction. All seven patients with definite symptoms had a marked increase in phase spread and severe volume overload.

Molecular cloning and sequencing of a rat preprogastrin complementary deoxyribonucleic acid

Gastrin biosynthesis involves a complex series of posttranslational modifications; their elucidation requires a knowledge of the structure of the gastrin precursor. The complete structure of rat preprogastrin was deduced from the nucleotide sequence of a full length cDNA clone isolated from a rat antral cDNA library. Northern blot hybridization analysis of rat antral RNA together with human antral RNA, reveals a single mRNA species of approximately 670 bases. Comparison of this sequence with those of porcine and human gastrin reveals extensive (73%) homology in the gastrin coding region as well as short regions of conserved nucleotides in the noncoding regions. The rat sequence encodes a preprogastrin of 104 amino acids which consists of a signal peptide, a 37 amino acid prosegment; and the gastrin 34 sequence, followed by a glycine (the amide donor), and flanked by pairs of arginine residues. Cleavage at an internal pair of lysine residues yields gastrin 17. Unlike the human and porcine sequences, rat preprogastrin contains a 9 amino acid carboxy-terminal extension peptide (-Ser-Ala-Glu-Glu-Glu-Asp-Gln-Tyr-Asn) which is homologous to the midportion of gastrin 17 including the site of tyrosine sulfation.