The Roles of USG and NCCT in the Diagnosis of Acute Appendicitis: A Study in a Tertiary Care Center in North Eastern India

Background

Acute appendicitis is a common cause of hospital admission and emergency laparotomy among children and young adults. Although the diagnosis is clinical, the use of radiological imaging has emerged over the past decades. Its principal use is as a problem-solving tool in equivocal cases. Owing to the increased use of imaging in the last few years, the negative appendicectomy rate has dropped significantly. In this prospective observational study, we compared the diagnostic accuracy of Ultrasonography and Non-Contrast Computed Tomography.

Method

One hundred and eighteen patients with clinically suspected appendicitis followed a designed protocol. Patients underwent appendicectomy after a first performed positive ultrasonography or after a positive Non-Contrast Computed Tomography when Ultrasonography was equivocal or nonspecific. When any other diagnosis was apparent in either imaging modality which could explain the symptomatology in the patient, they were considered negative for acute appendicitis and treated accordingly.

Results

The respective sensitivity, specificity, and accuracy for Ultrasonography, Non-Contrast Computed Tomography, and the whole diagnostic pathway for the diagnosis of acute appendicitis were 70.73%,80.83%, and 78.54; 100%,100%,100%, and 83.6%; and 100%,83.33% and 94.92%.

Conclusion

Using Ultrasonography as the first-line diagnostic tool and Non-Contrast Computed Tomography as a complementary second-line diagnostic tool, appendicitis can be diagnosed with high accuracy and the negative laparotomy rate can be brought down significantly without any increase in the risk of complications. Computed Tomography is superior to Ultrasonography for the diagnosis of acute appendicitis.

Persistent Primitive Trigeminal Artery – A Rare Vessel

Primitive carotido vertebral anastomosis is a well-recognized entity. During intrauterine development, craniovertebral blood circulation is characterized by temporary connections between the primitive internal carotid and dorsal longitudinal neural arteries. With normal development, they regress in the prenatal period. The most common of these is a persistent primitive trigeminal artery (PPTA) We report the case of a young male patient with intracranial bleed in the left capsuloganglionic region who was subsequently found to have a persistent primitive trigeminal artery on Magnetic Resonance Imaging Angiography.

Treatment of long bone infection by a biodegradable bone cement releasing antibiotics in human

Repair of methicillin-resistant Staphylococcal (MRSA) chronic osteomyelitis and resulting bone defect is one of the major challenges in orthopaedics. Previous study has shown the effectiveness of antibiotic loaded biodegradable composite bone cement with in vitro tests and in the treatment of experimental osteomyelitis. The cement is composed of poly(lactide-co-glycolide) encapsulated antibiotic-biphasic calcium phosphate granule complex and additive antibiotic powder in gypsum binder. In this study, the cement was studied further to evaluate its in vitro biological properties (cytocompatibility, platelet activation), anti-infective, and bone regenerative potential in comparison to poly(methyl methacrylate) (PMMA) cement and parenteral therapy in 43 patients (age 5-57 years) with chronic MRSA osteomyelitis by analyzing the results of histopathology, radiographs, magnetic resonance imaging, scanning electron microscopy, and serum drug concentrations for 1 year. The composite cement showed superior cytocompatibility and coagulant activity compared to PMMA cement. Moreover, the results of different postoperative clinical and radiological examinations also proved the supremacy of composite cement over the other treatment modalities in terms of success rate, faster sepsis control and bone regeneration. Low serum antibiotic concentrations and normal serum calcium levels indicate that the calcium-rich composite cement is safe for application in human. Therefore, we conclude that the composite bone cement is a promising candidate for the treatment of chronic osteomyelitis.

Joint scores in hemophilic arthropathy in children: Developing country perspectives

OBJECTIVE

Hemophilia is a common X-linked recessive coagulopathy causing recurrent bleeding into the synovial joints and results in articular and periarticular abnormalities. To our knowledge, this is the first comprehensive study aimed at studying the clinico-radiological joint score evaluation in hemophilic arthropathy in children from a developing country and its possible impact on the quality of life.

METHODS

In this hospital-based, prospective, descriptive study, all children presenting to the pediatric rheumatology clinic were studied. The joint physical examination was scored using the Hemophilia Joint Health Score 2.1 (HJHS 2.1). The patients were then subjected to imaging of the most affected joint using ultrasonography (USG) and magnetic resonance imaging (MRI). Detailed USG and MRI radiological evaluation was recorded in the predesigned proforma using the Hemophilia Early Arthropathy Detection with Ultra Sound (HEAD-US) score and MRI DENVER score. The physical quality of life as per Functional Independence Score in Hemophilia (FISH) was noted. The clinical, radiological, and functional scores were analyzed with an appropriate statistical measure.

RESULTS

The mean age at presentation was 7.4 years (interquartile range 4.9-10), with the knee being the most common joint involved. All of the USG score, MRI score, and FISH score have a significant correlation (p<0.05), with the HJHS 2.1 score with correlation coefficients of 0.7086, -0.8916, and 0.8607, respectively. USG and MRI had a correlation coefficient of -0.7145 and -0.8326 with FISH, respectively.

CONCLUSION

The degree of association between HJHS 2.1 score was found to be maximum with HEAD-US score, whereas a negative correlation was seen evaluating FISH score with both HEAD-US and MRI DENVER scores. Use of these scores, specifically HEAD-US score, will result in consistent assessment of hemophilic joints, optimizing the management of the destructive changes.

Medical students perception of ultrasound and computed tomography sessions in gross anatomy curriculum: a study in an Indian medical college

Background: Integration of Ultrasonography (USG) and Computed Tomography (CT) sessions into medical curriculum has been started and numerous studies show that they could be useful in anatomy teaching as an adjunct to traditional ways including didactic lectures, cadaveric material or 3D models. Information regarding the benefit and feasibility of integrating radiology sessions into Indian medical curriculum is still lacking.Methods: We introduced didactic and practical sessions of USG and CT focusing on Liver morphology into first year anatomy course and found out student’ perception by Likert- scale type questionnaire at the end. We collected opinions once again from the same cohort during their clinical rotations as junior doctors regarding the effectiveness of radiological sessions at very beginning of their career.Results: The first year students stated that radiology sessions were very interesting (97%) and effective (95%) to improve their anatomy understanding, 93% indicated it will make them more confident while taking practical examinations, 97% indicated such sessions should be incorporated in current anatomy curriculum. Majority of junior doctors (88% of responders) accepted the importance of early exposure to practical radiology in medical curriculum and recommended to include practical USG and CT sessions in anatomy course.Conclusions: This study was first to experiment the impact of practical radiology sessions in anatomy and collect feedback from both first year students and junior doctors in an Indian medical college. Our study shows it is possible and beneficial to include structured ultrasonography and CT sessions to the present MBBS curriculum in conjunction with traditional teaching methods.

Ruptured submitral aneurysm

Submitral aneurysm is a rare entity, with around few hundred cases reported till date. Presentation can be varied. We describe here a case of submitral aneurysm in a young male with rupture into the left atrium cavity.

Refractory Seizure in Childhood: Dyke-Davidoff-Masson Syndrome Revisited

Dyke-Davidoff-Masson syndrome (DDMS) is a rare disorder characterized by recurrent seizures, facial asymmetry, contralateral hemiplegia, radiologic features of cerebral hemiatrophy, and ipsilateral compensatory hypertrophy of the skull bone and sinuses. We describe three cases of children with DDMS, who initially presented with refractory seizure to the pediatric department of North Bengal Medical College and Hospital, India. In each case, the clinical features noted along with computed tomography or magnetic resonance imaging helped confirm the diagnosis of DDMS. DDMS should be considered as a differential diagnosis of refractory seizures in children. We seek to emphasize the importance of thorough clinical and neuroimaging workup of seizure disorder in children for the proper management of the condition.

Osteomeatal Complex: A Study of Its Anatomical Variation Among Patients Attending North Bengal Medical College and Hospital

Lateral nasal wall of each nasal cavity provides the final common pathway of drainage of the mucociliary clearance of frontal, maxillary and anterior ethmoidal air cells. Anatomical variants like concha bullosa, Haller cells, agger nasi cells, enlarged bulla ethmoidalis may obstruct the mucociliary clearance through osteomeatal complex and cause rhino sinusitis. The objectives were to find out the anatomical variation of osteomeatal complex and its dimensions when present. The present study was a descriptive, hospital based cross sectional study carried out in the outpatient departments of North Bengal Medical College and Hospital, West Bengal, India, among patients aged 15 years and above. Coronal CT scan of paranasal sinus and orbit region was done. Data was collected with the help of semi structured predesigned and pretested questionnaire. Of the 44 study patients, 15.9 % had concha bullosa, 11.36 % had paradoxical middle concha, 27.3 % had Haller cell, 18.2 % had agger nasi cell. Lateral attachment and medial free margin of uncinate process were also measured in respect to medial body line. 77.3, 59.1 and 47.7 % had sneezing, rhinorrhoea and headache respectively. The harmony of mucociliary clearance and obstruction free osteomeatal complex is the key factor for ventilation and drainage of maxillary, frontal and anterior ethmoidal air cells.

A case of bilaterally elongated styloid process differing in osseo-morphology

In a cranium of a male cadaver styloid processes have been found to be unusually long with different lengths. Elongation of styloid process involvethe entire 'Stylohyoid complex/chain', though not rare as reported in earlier literatures, but the osseomorphological and radiological analysis of present case brings out a unique variety as its described in the article.

Image quality associated with the use of an MR-compatible incubator in neonatal neuroimaging

OBJECTIVES

MRI in the neonate poses significant challenges associated with patient transport and monitoring, and the potential for diminished image quality owing to patient motion. The objective of this study was to evaluate the usefulness of a dedicated MR-compatible incubator with integrated radiofrequency coils in improving image quality of MRI studies of the brain acquired in term and preterm neonates using standard MRI equipment.

METHODS

Subjective and objective analyses of image quality of neonatal brain MR examinations were performed before and after the introduction of an MR-compatible incubator. For all studies, the signal-to-noise ratio (SNR) was calculated, image quality was graded (1-3) and each was assessed for image artefact (e.g. motion). Student's t-test and the Mann-Whitney U-test were used to compare mean SNR values.

RESULTS

39 patients were included [mean gestational age 39 weeks (range 30-42 weeks); mean postnatal age 13 days (range 1-56 days); mean weight 3.5 kg (range 1.4-4.5 kg)]. Following the introduction of the MR-compatible incubator, diagnostic quality scans increased from 50 to 89% and motion artefact decreased from 73 to 44% of studies. SNR did not increase initially, but, when using MR sequences and parameters specifically tailored for neonatal brain imaging, SNR increased from 70 to 213 (p=0.001).

CONCLUSION

Use of an MR-compatible incubator in neonatal neuroimaging provides a safe environment for MRI of the neonate and also facilitates patient monitoring and transport. When specifically tailored MR protocols are used, this results in improved image quality.

Sirenomelia

Sirenomelia is a rare malformation of caudal part of embryo. It is characterised by complete or partial fusion of the legs into a single lower limb. Abnormalities of the kidneys, large intestines and genitalia are common. Sirenomelia cases have only one umbilical artery and one vein. Upper body birth defects are rare and include abnormalities of heart, lungs, arms, spine and brain. Here we report a case of sirenomelia with uncommon upper body birth defects involving right forearm and hand, and the rib cage. Vascular steal phenomenon cannot explain the upper body birth defects.

Guided fine needle aspiration cytology of retroperitoneal masses - Our experience

Background:

Early pathological classification of retroperitoneal masses is important for pin-point diagnosis and timely management.

Aims:

This study was done to evaluate the usefulness and drawbacks of guided fine needle aspiration cytology (FNAC) of retroperitoneal masses covering a period of two years with an intention to distinguish between neoplastic and non-neoplastic lesions and to correlate with histologic findings.

Materials and Methods:

FNAC was done under radiological guidance in all cases using long needle fitted with disposable syringe. Appropriate staining was done and cytology was correlated with histology which was taken as the gold standard for comparison.

Results:

Fifty-one patients who presented with retroperitoneal masses were studied. Forty-four lesions were malignant cytologically and 7 were inflammatory (tuberculous). According to radiological and cytologic findings, we classified our cases into four groups: renal tumors, retroperitoneal lymphadenopathy, germ cell tumors, soft tissue tumors. Except for cases of non-Hodgkin lymphoma (NHL) and metastatic lesions, we had sensitivity and specificity of 100%. In NHL the sensitivity and specificity were both 50%. In cases of metastatic adenocarcinoma, the sensitivity and specificity were 84.6% and 81.8%, respectively.

Conclusions:

Ignoring the pitfalls, guided FNAC is still an inexpensive and reliable method of early diagnosis of retroperitoneal lesions.

Childhood steroid-responsive ophthalmoplegic migraine

Ophthalmoplegic migraine (OM) is characterized by recurrent attacks of headache with paresis of ocular cranial nerves. Previously, it was classified as a variant of migraine, but recently, International Headache Classification (IHCD-II) has reclassified OM to the category of neuralgia. Presently, OM is considered a type of recurrent demyelinating cranial neuropathy. We report an adolescent girl with OM, who had been treated with steroid and showed dramatic improvement.

A two-centre collaborative study on clinico-epidemiological profile of a recent outbreak of epidemic dropsy in New Delhi (India) with special emphasis on its cardiac manifestations in pediatric patients

A hundred and six clinically diagnosed cases of epidemic dropsy, admitted in June to August 1998 to the P-III unit of RML Hospital and the Department of Pediatrics, Safdarjang Hospital, were studied. All of them consumed mustard oil contaminated with Argemona mexicana, confirmed by ferric chloride and nitric acid tests. No specific sex predilection was seen. No child was affected below the age of 3 years. Pedal edema and reddish hyperpigmentation were the most consistent findings (100 per cent). Frank cardiac failure was seen in only 24 (22.64 per cent), yet persistent tachycardia was alarmingly high (104/106, i.e. 98.4 per cent). Notably ECG showed prolonged Q-T interval in 24 children (22.64 per cent), unrelated to serum Ca2+ level in patients with congestive cardiac failure (CCF). Color Doppler echocardiography showed biventricular dilatation in all the 24 patients with CCF. Wide pulse pressure was recorded in two patients only. Mortality occurred in only two patients (1.89 per cent). Eye involvement was a late finding. All those who survived (i.e. 104/106) recovered completely, except two patients who were left with sarcoid-like changes of skin telangiectasia.

Eosinophilic cholecystitis as a possible late manifestation of the eosinophilia-myalgia syndrome

We describe a case of acute acalculous cholecystitis occurring in a 43-year-old woman with a history of the eosinophilia-myalgia syndrome, associated with the ingestion of 1-tryptophan. The patient underwent a laparoscopic cholecystectomy and subsequent histological examination of the gallbladder revealed an infiltrate predominantly of eosinophils, suggesting a possible relationship to the underlying condition. This may represent a late complication of the eosinophilia-myalgia syndrome--such an association has not previously been reported in the literature. The gastrointestinal and hepatic complications of this syndrome are discussed.

Experimental investigation and mathematical modeling of Pluronic F127 gel dissolution: drug release in stirred systems

We have examined the dissolution of Pluronic F127 gels in a USP dissolution apparatus under stirred conditions, and simultaneously monitored the release of model drugs from these gels. The drugs selected were propranolol HCl, metronidazole and cephalexin. Our results show that drug release is zero-order and is controlled by the dissolution of the gel for all the drugs, under various conditions of temperature, F127 concentration, drug concentration, and for stirring speeds between 20 and 80 rpm. The addition of inorganic salts has no significant effect on dissolution rate or drug release. Increasing F127 concentration in the gel decreases gel dissolution and drug release rates. We have developed a predictive mathematical model based on the assumption that uptake of water into the gel and subsequent disentanglement of F127 micelles control gel dissolution. There is good agreement between experimental results and model predictions for stirring speeds above 20 rpm. As stirring speed is decreased to 20 rpm and below, there are discrepancies between actual and predicted values, presumably due to a significant diffusion component that contributes to drug release.

Non-specific inflammatory gingival enlargement--a case report

An unusual case of unilateral idiopathic gingival hyperplasia in a 6 year old child is reported and its management discussed.

Effect of Salts on the Micellization, Clouding, and Solubilization Behavior of Pluronic F127 Solutions

We have examined the effect of NaCl, Na(2)SO(4), Na(3)PO(4), and NaSCN on F127 solutions; properties examined were critical micellization temperature (cmt), cloud point, and solubilization of a model hydrophobic drug, propyl paraben. Static light scattering showed that the first three salts lower the cmt of F127 in the order Na(3)PO(4)>Na(2)SO(4)>NaCl. The extent of lowering depends on the salt concentration and can be ascribed to the water structure-making properties of these salts. NaSCN, a water structure breaker, was found to increase cmt. Pyrene fluorescence was used to study the changes in micellar interior in the presence of salts. We found that the micellar micropolarity is not significantly changed by salts, evidenced by a constant I(1)/I(3) ratio of pyrene. However, the I(e)/I(3) ratio changes significantly with salts, being lower for NaCl, Na(2)SO(4), and Na(3)PO(4) and higher for NaSCN. This is consistent with an increase in the total hydrophobic micellar domain, in micellar microviscosity, or both. Solubilization of propylparaben increases in the presence of Na(3)PO(4), consistent with a larger hydrophobic domain for solubilization. The thermodynamics of micellization continue to be entropically driven in the presence of salts, evidenced by a positive entropy overcoming an unfavorable enthalpy. Copyright 2000 Academic Press.

A Study of the Temperature-Dependent Micellization of Pluronic F127

We have examined the temperature-dependent micellization of the pharmaceutically important PEO-PPO-PEO copolymer, Pluronic F127, using static light scattering and various aspects of the pyrene fluorescence spectrum (monomer intensity, excimer formation and the I1/I3 ratio). All techniques gave essentially the same value for the critical micellization temperatures (cmt) of various F127 solutions, and our results agreed with those reported in the literature. Cmt values decrease with increasing F127 concentration. We observed significant solubilization of pyrene in F127 solutions below the cmt, which was also reflected in the measured I1/I3 ratios. The thermodynamics of the micellization process were studied and gave different results at low and high F127 concentrations. In the low F127 concentration range (up to approximately 50 mg/mL), we obtain DeltaH = 312 kJ mol-1 and DeltaS = 1.14 kJ mol-1 K-1. Above 50 mg/mL we obtain DeltaH = 136 kJ mol-1 and a DeltaS = 0.54 kJ mol-1 K-1. This discontinuity in thermodynamic behavior can be due to a change in aggregation number with temperature and/or a change in the micellization process at higher concentrations. Copyright 1999 Academic Press.

Conjunctival impression cytology for detection of early vitamin A deficiency in children

Children presenting with recurrent infections have a high risk of developing vitamin A deficiency. Conjunctival impression cytology (CIC) was used in the present study in such children to detect subclinical deficiency and to monitor the outcome after therapy. Seventy children with history of recurrent infections, and 10 healthy children in the age group of six months to five years were included in the study. CIC was performed using millipore filter paper and stained with PAS stain. A three tier grading system was used consisting of normal, borderline abnormal and abnormal for interpretation. Vitamin A supplementation was given in children in the latter two categories. Repeat cytology showed reversal to normal in these children. Hence in children with high risk of developing vitamin A deficiency, it is suggested to do CIC for detection and monitoring it.

The 'mouse face' appearance of the vertebrae in Paget's disease

Paget's disease is occasionally found as an incidental finding on bone scans performed for the evaluation of metastatic disease, which causes a diagnostic and a subsequent therapeutic dilemma. We have previously described the "Mouse Face" appearance of vertebrae on bone scans (increased uptake in the vertebral body, posterior elements, and the spinous process), which was fairly specific for Paget's disease in a small series. This retrospective study was undertaken to determine if this observation holds true in a larger series. Bone scans performed in 2,881 patients were randomly selected, and were reviewed by 2 physicians. Thirty-nine cases with a "Mouse Face" appearance were identified. Diagnosis was established in 30 of the 39 patients by correlative radiographic studies and/or clinical follow-up. Twenty patients were referred for the evaluation of possible metastases, and 7 were found to have metastases at the sites of "Mouse Face". The other 13 had Paget's disease. However, 6 of the 7 patients with metastases had extravertebral findings compatible with multiple metastases, and the remaining patient had a "Mouse Face" lesion only, with a question of metastases. Ten patients were evaluated for Paget's disease or others, and none of them had metastases at the site of the "Mouse Face". The "Mouse Face" appearance is more suggestive of Paget's disease than metastases even in patients with cancer. These patients should be assumed unlikely to have vertebral metastases, unless proven by another correlative radiologic study.

Brain perfusion imaging during preoperative temporary balloon occlusion of the internal carotid artery

The main objective of this study was to assess whether 99mTc-HMPAO brain SPECT imaging can identify patients at high risk of developing an infarct following permanent carotid occlusion in the course of brain surgery.

METHODS

Test balloon occlusion of the internal carotid artery was performed in 44 patients with a variety of head and neck tumors or aneurysms. Technetium-99m-HMPAO was injected intravenously while the balloon was initiated and a SPECT study was obtained 30 min later. Follow-up CT scans were obtained routinely for all patients at 2 wk and 1 mo following surgery, or earlier when necessary. Thirty patients and five normal volunteers had semiquantitative analysis of cerebral perfusion.

RESULTS

Twenty-six patients demonstrated ipsilateral perfusion abnormalities during trial occlusion. Eight patients in this group underwent bypass grafting prior to sacrifice of the artery: two resulting in infarcts. Eighteen patients had symmetric cerebral perfusion during occlusion and four of these patients underwent permanent therapeutic carotid occlusion; three patients had subsequent infarcts and the fourth patient had an impending stroke.

CONCLUSION

Patients with symmetric cerebral perfusion measured by 99mTc-HMPAO SPECT may still have a high long-term complication rate following carotid sacrifice. The scan findings in these patients were not predictive of the outcome. Patients with asymmetric cerebral perfusion had alternative therapeutic approach to carotid sacrifice and most of them had good surgical outcomes.

Reversible cerebral perfusion abnormalities associated with cyclosporine therapy in orthotopic liver transplantation

A 60-yr-old woman experienced several episodes of generalized seizures following 2 wk of immunosuppressive therapy with cyclosporine for orthotopic liver transplantation. CT showed low density in the white matter of the parieto-occipital lobes. A 99mTc-HMPAO brain SPECT showed diminished perfusion in the parieto-occipital cortex bilaterally. Although the cyclosporine was discontinued, the patient's neurologic status initially worsened and then improved over the next several days. Repeat perfusion brain SPECT showed resolution of most of the perfusion abnormalities, while repeat CT showed persistent white matter changes in the parieto-occipital lobes. We report the presence of reversible cortical perfusion abnormalities in conjunction with cyclosporine therapy. The findings suggest that perfusion brain SPECT may be a sensitive monitor of cyclosporine-induced neurotoxicity.

Variable expression of the Opc outer membrane protein in Neisseria meningitidis is caused by size variation of a promoter containing poly-cytidine

Opa proteins of Neisseria meningitidis exhibit translational phase variation via addition or deletion of repetitive coding repeat units within the DNA encoding the protein leader sequence. In contrast, Opc phase variation is the result of transcriptional regulation. Transcription starts 13 nucleotides after the -10 region of an unusual promoter sequence containing a variable number of contiguous cytidine residues and lacking a -35 region. Efficient expression of Opc occurred in strains with 12 to 13 cytidine residues, intermediate expression in strains with 11 or 14 residues and no expression with < or = 10 or > or = 15 residues. This unusual regulation may have evolved because the Opc protein enables meningococcal invasion and is immunogenic.

Long term performance of atrial leads

Long term performance of 163 atrial leads implanted in 158 patients between July 1981 and June 1993 was evaluated. There were 122 DDD and 36 AAI units, with 125 (77%) polyurethane and 38 (23%) silicone leads. One hundred and nine (67%) unipolar and 54 (33%) bipolar leads were used. Patients were followed in the Pacemaker Clinic for 6 to 124 months (mean 50 +/- 39 months). Five patients were lost to follow up. Transient malfunction was observed in 18 cases (sensing 13, pacing 5) within the first 2 weeks. In 13 cases failure to sense subsided spontaneously and in 4 pacing malfunction could be corrected by reprogramming. Lead dislodgement occurred in 4 patients (2.5%), all within the first week. After the 1st month malfunction was uncommon. Between 1 and 12 months undersensing occurred in 4 (2.5%). In 3 cases it could be corrected by reprogramming. In the first year, reoperation was performed in 5 cases for lead related problems (3 dislodgements, 2 insulation failures). Beyond 12 months complications were as follows: failure to sense-8 (5%), failure to pace-3 (2%), insulation break -1 (0.6%). Majority of these problems could be managed by reprogramming. Reoperation was performed in 1 case with insulation break. The pacing mode had to be changed in 5 (3%) patients with dual chamber units who had loss of P wave sensing. During follow-up 98%, 98%, 96%, 95% and 83% of the leads were working satisfactorily at 1,2,3,4 and 9 years respectively. Thus atrial leads have excellent long term performance and an acceptable rate of late malfunction.

Long term performance of silicone insulated and polyurethane insulated cardiac pacing leads

The long term performance of various pacing leads in use for at least one year is reported from one centre. Between January 1975 and December 1990, 1056 cardiac pacing leads were implanted in 881 patients (mean age 57 +/- 13 years). Eight hundred and three leads were silicone insulated (SI) and 253 leads were polyurethane insulated (PUI). Leads from different manufacturers were used (Medtronic, CPI, Telectronics). The average duration of follow up was 56.6 +/- 77 months (range 12-221 months) for SI and 47.1 +/- 24 months (range 12-99 months) for PUI leads. Overall lead failure occurred more often in the PUI group (n = 46, 18.2%) compared to SI group (n = 93, 11.3%, p < 0.025). Majority of lead failures occurred in the first 36 months after implantation. In particular, Medtronic models 6971, 6972 (urethane) and 6901 (silicone) showed higher rate of complications (25.5%, 26.3% and 44.5% respectively).

Acute hemodynamic effects of different atrioventricular intervals in dual chamber pacemakers: is there an optimum atrioventricular delay

Conflicting data have been reported regarding adjustment of atrioventricular (AV) interval to maximise hemodynamic performance of dual chamber pacemakers. Eleven consecutive patients with complete heart block and dual chamber pacemakers were paced at three AV intervals (150, 200, 250 msec) and free running rates (60-93 bpm, mean 73 +/- 12 bpm) with simultaneous measurements of cardiac output, atrial contribution to left ventricular filling, left ventricular ejection fraction, and peak aortic velocity and acceleration by echo-Doppler techniques to define the optimum AV delay. At all the three AV intervals tested there was no difference in cardiac output (4.7 +/- 0.96, 4.83 +/- 1.12, 4.77 +/- 1.19 litres/min respectively, p = NS), left ventricular ejection fraction (60.2 +/- 10.6%, 61.2 +/- 9.9% and 64 +/- 8.3%, p = NS), atrial contribution to left ventricular filling (0.37 +/- 0.10, 0.38 +/- 0.09, 0.36 +/- 0.16, n = 8, p = NS), peak aortic velocity (104 +/- 8, 105 +/- 12, 104 +/- 13 cm/sec, p = NS) and aortic acceleration (19.68 +/- 4.26, 20.4 +/- 5.58 and 19.0 +/- 4.54 m/sec2, p = NS). Compared to AV delay of 150 msec an increase in cardiac output of 0.5 L/minute was observed in three patients at an AV delay of 200 msec and in one patient at the AV delay of 250 msec. These data suggest that it is difficult to generalize an optimum AV delay in patients with dual chamber pacemakers. With the AV interval in the range of 150-250 msec, only a minority of patients could improve their haemodynamics at rest by adjusting this interval if the baseline cardiac function was normal.