Electron microscopy of fine-needle aspiration biopsy specimens: a brief review

The cellular sample obtained by fine-needle aspiration biopsy is usually small and therefore requires extreme care during processing for electron microscopy. The most significant technical problem is due to contamination of the sample by red blood cells, which tend to dilute the samples. Red blood cells in these samples may be removed prior to processing by either using Bovine serum albumin as a gradient or by filtration of the specimen by a nylon sieve. Experience at our institution with the use of electron microscopy for interpretation of fine-needle aspiration biopsy samples is briefly reviewed.

Fine-needle aspiration biopsy of pediatric neoplasms: correlation between electron microscopy and immunocytochemistry in diagnosis and classification

A series of fine-needle aspiration biopsies performed in 635 children were reviewed. The diagnoses rendered in these patients included malignant lymphoma in 139 (21.9%); Hodgkin's disease, 25 (3.9%); neuroblastoma, 58 (9.1%); Wilms' Tumor, 37 (5.8%); Ewing's sarcoma, 32 (5.0%); rhabdomyosarcoma, 25 (3.9%); retinoblastoma, 22 (3.5%); leukemia infiltrate, 33 (5.2%); and miscellaneous tumors, 52 (8.2%). In 171 patients (26.9%), the biopsy was nondiagnostic. The cytomorphological characteristics of these lesions are briefly described and illustrated. Salient morphological features are further correlated with histological and ultrastructural appearances. Immunocytochemical patterns of these tumors are also discussed briefly.

Iontophoretic transmyocardial drug delivery. A novel approach to antiarrhythmic drug therapy

BACKGROUND

Antiarrhythmic drugs often fail to achieve therapeutic effects without toxic systemic levels. Direct transport of drugs into the myocardium may circumvent this problem and may also provide new insights into antiarrhythmic drug effect on arrhythmogenic tissues. In a canine model, procainamide (PA) was delivered iontophoretically using pulsed current synchronized with the ventricular depolarization via an implantable defibrillator patch electrode that was modified to contain a 3.6-ml chamber. Myocardial tissue concentrations of PA were evaluated in 7-day myocardial infarcts (n = 16) that were exposed to 10 minutes of iontophoretic PA delivery and compared with passive diffusion (n = 5) and intravenous (n = 16) PA. These dogs were followed for 3 hours. The infarcted tissue PA levels were compared with normal myocardium. Coronary and systemic blood levels of PA, effective refractory period (ERP), diastolic threshold, and efficacy of ventricular tachycardia (VT) suppression were evaluated throughout the follow-up period.

METHODS AND RESULTS

Three hours after 10 minutes of iontophoretic, passive, and intravenous PA, the epicardial layer concentration in the center of the infarcted zone was 840 +/- 853 micrograms/g, 93 +/- 90 micrograms/g, and 15 +/- 8 micrograms/g of tissue, respectively. In the endocardial layer, the PA concentrations with iontophoresis were 38 +/- 57 micrograms/g and were significantly higher than those achieved with either passive diffusion 38 +/- (4 +/- 2 micrograms/g) or with intravenous delivery (11 +/- 5 micrograms/g) (p less than 0.05). Epicardial tissue PA concentrations 3 hours after iontophoresis, passive diffusion, and intravenous PA in the normally perfused tissues were 14 +/- 13 micrograms/g, 3 +/- 2 micrograms/g, and 16 +/- 8 micrograms/g of PA, respectively. Venous blood levels were 2 +/- 3 micrograms/ml 3 hours after iontophoresis, 1 +/- 1 microgram/ml 3 hours after passive PA delivery, and 11 +/- 7 micrograms/ml with intravenous administration (p less than 0.05 intravenous versus passive and iontophoresis). Iontophoretic delivery of PA resulted in 22 +/- 29 msec ERP prolongation intramurally in the infarcted zone with no significant normal tissue ERP prolongation. Passive delivery of PA produced no significant changes in ERP. After intravenous infusion, the ERP in the infarcted zone increased by 35 +/- 29 msec and 13 +/- 12 msec in the normal tissue. Sustained monomorphic VT was induced in 20 animals. In one of these animals, only nonsustained VT could be induced at baseline; however, after intravenous PA, VT could be induced and remained inducible throughout the 3-hour follow-up period. In the iontophoretic delivery group, PA suppressed VT in all of the animals, with termination time ranging from 20 seconds to 7 minutes. In three cases, sustained monomorphic VT could be reinduced, two after 60 minutes and one after 120 minutes. However, in seven dogs, VT could not be induced during the 3-hour follow-up period. None of the dogs in which PA was delivered iontophoretically into the infarcted myocardium developed VT that was not induced before delivery of the drug. Intravenous PA administration resulted in VT suppression in one of 10 dogs. In two dogs, VT could not be induced before intravenous infusion of PA. However, after intravenous PA, VT could be induced. Immunohistochemical mapping of the PA within the infarcted tissue revealed transmural PA distribution.

CONCLUSIONS

These data show that 1) the delivery of high transmural concentrations of PA directly into infarcted myocardium is both feasible and effective...

Induction of ventricular fibrillation versus monomorphic ventricular tachycardia during programmed stimulation. Role of premature beat conduction delay

BACKGROUND

Premature stimuli can cause ventricular fibrillation (VF) during electrophysiological testing. The electrophysiological correlations associated with the onset of VF were evaluated in 40 patients who had this rhythm induced during programmed ventricular stimulation. These parameters were compared with those observed in 51 patients who had inducible sustained monomorphic ventricular tachycardia (VT) and 45 patients who had no inducible sustained ventricular tachyarrhythmias.

METHODS AND RESULTS

Shortest premature coupling intervals for S2, S3, and S4 at induction of tachycardia or before achieving refractoriness, corresponding conduction latencies (defined as the time from the premature stimulus to the upstroke of the depolarization wave front recorded 35 mm away from the stimulation site), and ventricular activation times (defined as the time from the premature stimulus to the end of the depolarization wave) were compared. The mean coupling intervals were longest in the inducible VT patients: 300 +/- 30, 254 +/- 57, and 228 +/- 32 msec for S2, S3, and S4, respectively. In the inducible VF group, the coupling intervals were 260 +/- 37, 208 +/- 20, and 213 +/- 30 msec. In the group with no inducible VT or VF, these coupling intervals were 251 +/- 24 (p less than 0.01 versus inducible VT group), 209 +/- 27 (p less than 0.001 versus inducible VT group), and 194 +/- 21 msec (p less than 0.05 versus inducible VT and VF groups). The coupling interval of the last premature extrastimulus was above 200 msec in 70% of the patients in whom VF was induced. The largest increases in latency and activation times were recorded in patients in whom VF was induced. The cumulative increase in latency, defined as increased conduction time from baseline, summed for all the premature stimuli was also the greatest at initiation of VF. In contrast, the smallest increases in these parameters were noted in the patients with no inducible VT or VF. Measurements of total activation time yielded similar results as those recorded for latencies. The most important parameters distinguishing the VT patient population from the other two groups were the low ejection fractions and the longer coupling intervals at which VT was induced, whereas in the VF group, the most important discriminating factor was cumulative activation time. Sixty-three percent of the inducible VF patients presented with abnormal hearts (myocardial infarction or cardiomyopathy), whereas 88% of the inducible VT patients had abnormal hearts. In contrast, only 25% of the patients in whom no arrhythmia was induced presented with abnormal hearts. Mean ejection fraction was 32 +/- 15% for the inducible VT group, 45 +/- 13%* for the inducible VF group, and 51 +/- 17%* for patients with no inducible VT/VF (*p less than 0.001 versus VT).

CONCLUSIONS

The results suggest that 1) initiation of ventricular tachycardia during programmed ventricular stimulation occurs with minimal conduction latency; 2) because of the large overlap in coupling intervals where VF or VT were induced, a single coupling interval cannot be recommended to adequately separate these groups; and 3) induction of VF was preceded by increased latency and prolongation of the local activation time. These parameters should not be allowed to prolong if VF is to be avoided during programmed stimulation. In addition, 4) the initiation of VF during electrophysiological studies is often associated with the presence of structural heart disease; such structural disease may promote conduction latency and the development of VF.

Selective transcatheter ablation of the fast and slow pathways using radiofrequency energy in patients with atrioventricular nodal reentrant tachycardia

BACKGROUND

The safety and efficacy of selective fast versus slow pathway ablation using radiofrequency energy and a transcatheter technique in patients with atrioventricular nodal reentrant tachycardia (AVNRT) were evaluated.

METHODS AND RESULTS

Forty-nine consecutive patients with symptomatic AVNRT were included. There were 37 women and 12 men (mean age, 43 +/- 20 years). The first 16 patients underwent a fast pathway ablation with radiofrequency current applied in the anterior/superior aspect of the tricuspid annulus. The remaining 33 patients initially had their slow pathway targeted at the posterior/inferior aspect of the right interatrial septum. The fast pathway was successfully ablated in the initial 16 patients and in three additional patients after an unsuccessful slow pathway ablation. A mean of 10 +/- 8 radiofrequency pulses were delivered; the last (successful) pulse was at a power of 24 +/- 7 W for a duration of 22 +/- 15 seconds. Four of these 19 patients developed complete atrioventricular (AV) block. In the remaining 15 patients, the post-ablation atrio-His intervals prolonged from 89 +/- 30 to 138 +/- 43 msec (p less than 0.001), whereas the shortest 1:1 AV conduction and effective refractory period of the AV node remained unchanged. Ten patients lost their ventriculoatrial (VA) conduction, and the other five had a significant prolongation of the shortest cycle length of 1:1 VA conduction (280 +/- 35 versus 468 +/- 30 msec, p less than 0.0001). Slow pathway ablation was attempted initially in 33 patients and in another two who developed uncommon AVNRT after successful fast pathway ablation. Of these 35 patients, 32 had no AVNRT inducible after 6 +/- 4 radiofrequency pulses with the last (successful) pulse given at a power of 36 +/- 12 W for a duration of 35 +/- 15 seconds. After successful slow pathway ablation, the shortest cycle length of 1:1 AV conduction prolonged from 295 +/- 44 to 332 +/- 66 msec (p less than 0.0005), the AV nodal effective refractory period increased from 232 +/- 36 to 281 +/- 61 msec (p less than 0.0001), and the atrio-His interval as well as the shortest cycle length of 1:1 VA conduction remained unchanged. No patients developed AV block. Among the last 33 patients who underwent a slow pathway ablation as the initial attempt and a fast pathway ablation only when the former failed, 32 (97%) had successful AVNRT abolition with intact AV conduction. During a mean follow-up of 6.5 +/- 3.0 months, none of the 49 patients had recurrent tachycardia. Forty patients had repeat electrophysiological studies 4-8 weeks after their successful ablation, and AVNRT could not be induced in 39 patients.

CONCLUSIONS

These data suggest that both fast and slow pathways can be selectively ablated for control of AVNRT: Slow pathway ablation, however, by obviating the risk of AV block, appears to be safer and should be considered as the first approach.

D-alanine: D-alanine ligase of Escherichia coli. Expression, purification and inhibitory studies on the cloned enzyme

A 1.2 kb BamHI fragment from pDK30 [Robinson, Kenan, Sweeney & Donachie (1986) J. Bacteriol. 167, 809-817] was cloned in pDOC55 [O'Connor & Timmis (1987) J. Bacteriol. 169, 4457-4482] to give two constructs, pDOC89 and pDOC87, in which the Escherichia coli D-alanine:D-alanine ligase (EC 6.3.2.4) gene (ddl) was placed under the control of the lac and lambda PL promoters respectively. Both constructs, when used to transform E. coli M72, gave similar levels of expression of the ddl gene. The expressed enzyme was purified to homogeneity and the amino acid sequence of its N-terminal region was found to be consistent with that predicted from the gene sequence, except that the N-terminal methionine was not present in the mature protein. [1(S)-Aminoethyl][(2RS)2-carboxy-1-octyl]phosphinic acid (I), previously shown to bind tightly to Enterococcus faecalis and Salmonella typhimurium D-alanine:D-alanine ligases following phosphorylation Parsons, Patchett, Bull, Schoen, Taub, Davidson, Combs, Springer, Gadebusch, Weissberger, Valiant, Mellin & Busch (1988) J. Med. Chem. 31, 1772-1778; Duncan & Walsh (1988) Biochemistry 27, 3709-3714], was found to be a classical slow-binding inhibitor of the E. coli ligase.

Intracardiac rhabdomyosarcoma: transesophageal echocardiographic findings and diagnosis

Transesophageal echocardiography (TEE) was performed on a 41-year-old woman who presented with a cerebrovascular accident. TEE confirmed the presence of a morphologically bizarre biatrial tumor with precarious, vigorous motion throughout the cardiac cycle. Surgical intervention was decided on, and the patient underwent cardiac surgery for tumor excision 16 hours after TEE. Intraoperative frozen section diagnosis was spindle cell sarcoma, and subsequent immunohistochemical analysis showed the tumor to be a rhabdomyosarcoma. The data are presented here, and the role of TEE to establish a preoperative diagnosis of intracardiac tumor is discussed.

Use of intravenous esmolol to predict efficacy of oral beta-adrenergic blocker therapy in patients with neurocardiogenic syncope

The usefulness of esmolol in predicting the efficacy of treatment with an oral beta-adrenergic blocking agent was evaluated in 27 consecutive patients with neurocardiogenic syncope. Seventeen patients had a positive head-up tilt test response at baseline and 10 patients required intravenous isoproterenol for provocation of hypotension. All patients were then given a continuous esmolol infusion (500 micrograms/kg per min loading dose for 3 min followed by 300 micrograms/kg per min maintenance dose) and rechallenged with a head-up tilt test at baseline or with isoproterenol. Of the 17 patients with a positive baseline tilt test response, 11 continued to have a positive response to esmolol challenge. Sixteen patients (including all 10 patients with a positive tilt test response with isoproterenol) exhibited a negative response to upright tilt during esmolol infusion. Irrespective of their response to esmolol infusion, all patients had a follow-up tilt test with oral metoprolol after an interval of greater than or equal to 5 half-lives of the drug. All 16 patients (100%) with a negative tilt test response during esmolol infusion had a negative tilt test response with oral metoprolol. Of the 11 patients with a positive tilt test response during esmolol infusion, 10 (90%) continued to have a positive response with oral metoprolol. It is concluded that in the electrophysiology laboratory, esmolol can accurately predict the outcome of a head-up tilt response to oral metoprolol. This information may be helpful in formulating a therapeutic strategy at the initial head-up tilt test in patients with neurocardiogenic syncope.

Role of implantable cardioverter defibrillator therapy in the management of high-risk patients

Cardiovascular mortality from ventricular tachycardia (VT) and ventricular fibrillation (VF) continues to be a major health problem. Several therapeutic approaches are now available to treat patients with known VT/VF. Among the various therapeutic options are antiarrhythmic drugs, catheter or surgical ablation of VT focus, and implantable cardioverter defibrillator (ICD). The overall 2-year cardiovascular mortality is significantly reduced by ICD therapy. The ICD is particularly useful in patients with 1) no inducible but clinical VT/VF, 2) drug refractory VT/VF, and 3) VT/VF in association with left ventricular ejection fraction of less than or equal to 30%. Significant improvements in ICD therapy have already been made; these improvements include tiered antitachycardia therapy, antibradycardia pacing, lower defibrillation threshold, and longer life of generator. Further improvements are expected, including nonthoracotomy approach to defibrillation, pectoral implant, and dual chamber sensing. It is likely that with all of the advances in ICD therapy its acceptance as a therapeutic option will increase.

Malignant mesothelioma: King Faisal Specialist Hospital and Research Centre experience

Ten cases of malignant mesothelioma were diagnosed and treated at the King Faisal Specialist Hospital and Research Centre over a ten year period from 1977 to 1987. Seven of these cases were referred from the Southern Province and were clustered in the Al-Baha and Najran districts. In only one case (a plumber from Taif) was there the likelihood of occupation exposure. None of the patients had interstitial changes or pleura plaques on chest x-ray. Epidemiological studies are warranted to establish the etiology of mesothelioma in the Southern region of Saudi Arabia.

Does reception of appropriate shocks from the implantable cardioverter defibrillator affect survival?

The implantable cardioverter defibrillator has become an important therapeutic modality for treatment of life-threatening ventricular tachyarrhythmias. Recent reports have suggested that patients who receive appropriate shocks from this device have an inordinately high overall mortality, and questioned the extent of benefit these patients derive from the implant. This report analyzed the survival among 184 patients who received the implantable cardioverter defibrillator to assess survival differences between patients who received appropriate shocks versus those who did not. At a mean follow-up of 24 +/- 18.7 months, 68 patients received an appropriate shock from their device while 116 did not receive an appropriate shock. Overall survival of the entire population was quite similar to those published by others. There was no significant difference between overall survival of patients who received an appropriate shock versus those who did not. However, there was a statistically significant difference in sudden death mortality. The group of patients that received appropriate shocks included all five sudden deaths. This observation suggested that sudden death in this population was likely due to ventricular tachyarrhythmias rather than strictly bradycardia or asystole. The "benefit" of the device to the entire population was also assessed by estimating survival after receipt of the first appropriate shock. Using this approach, an estimated 10% of patients died without receiving an appropriate shock. In other words, ultimately, 90% of patients were expected to benefit from the device. This survival curve, which initiated only after receipt of the first appropriate shock was fairly similar to those estimated from conventional methods. Therefore, survival after receipt of an appropriate shock was comparable to overall survival and there was no significant difference between survival of patients who received appropriate shocks and those who did not.

When is it safe not to replace an implantable cardioverter defibrillator generator?

In most reports on patients receiving implantable cardioverter defibrillators, shocks were received mainly during the first 2 to 3 years. Thus, the question had been raised as to the need for device replacement after 3 or 4 years if no shocks had been received. In order to answer this question, shock experience in 184 patients receiving the implantable cardioverter defibrillator was analyzed. Patients were followed for a mean of 24 +/- 18.7 months. A patient's shock was judged to be appropriate if there was electrocardiographic documentation of sustained ventricular tachyarrhythmia at the time of shock or if it was preceded by sudden onset of presyncopal or syncopal symptoms. The majority of patients had coronary artery disease. In approximately two-thirds of patients, left ventricular ejection fraction was below 40%. One hundred fourteen patients had inducible sustained monomorphic ventricular tachycardia. On follow-up, there were 29 deaths, five of which were sudden. Sixty-eight patients received an appropriate shock during follow-up (37%). Over 90% of these 68 received their first shock within the 2 years after implant. The actuarial risk of receiving an appropriate shock by the fifth year after implant was 69%. Conversely, 31% of patients who survived 5 years had not received an appropriate shock. Hazard analysis indicates that there is a high incidence of first appropriate shock during the year following implant. Subsequently, the incidence dropped to a relatively steady rate with a rise in this rate during the fifth year. This analysis suggested a bimodal distribution of appropriate shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Ramadan fasting and thyroid hormone profile

A study comprising 41 males, 5 females of the age ranging from 28 to 56 years was conducted during Ramadan of 1989 to compare T3, T4 and TSH levels in fasting with the levels of non-fasting conditions. Each individual gave 6 blood samples: One sample was taken 20 days before the onset of Ramadan, 3 samples at different fasting days and last two samples were drawn 23 days and five months after the end of Ramadan, respectively. The results showed a significant gradual rise in TSH throughout the fasting month, although the mean levels remained within normal limits. Pre- Ramadan levels were re-attained well after the end of Ramadan. There was no significant change in T3 and T4 levels.

Echocardiographic demonstration of decreased left ventricular dimensions and vigorous myocardial contraction during syncope induced by head-up tilt

Two-dimensional echocardiography was performed during a head-up tilt test in 11 control subjects (group I) and 18 patients with recurrent unexplained syncope. In four patients (group II), the head-up tilt test was negative at baseline and after isoproterenol infusion. Syncope was induced during baseline head-up tilt in nine patients (group III) and after isoproterenol challenge in five (group IV). The echocardiographic variables assessed were left ventricular end-systolic and end-diastolic areas and percent fractional shortening. At the end of head-up tilt, end-systolic area decreased by 4.5 +/- 1.3 and 3.0 +/- 1.2 cm2 in groups III and IV, respectively, compared with 0.5 +/- 0.7 and 0.2 +/- 0.1 cm2 in groups I and II, respectively (p less than 0.04). Similarly, end-diastolic area decreased by 5.5 +/- 2.6 cm2 in group III compared with 2.7 +/- 1.9 and 1.75 +/- 0.4 cm2 in group I and II, respectively (p less than 0.04). Additionally, at the end of the baseline study, fractional shortening was significantly greater in group III and group IV (43 +/- 5%) than in groups I and II (p less than 0.01). In conclusion, syncope induced by head-up tilt is associated with vigorous myocardial contraction and a significant decrease in left ventricular end-systolic dimensions. This left ventricular hypercontractility may play an important role in the pathogenesis of syncope induced by head-up tilt.

Fine-needle aspiration biopsy (FNAB) diagnosis of testicular involvement in acute lymphoblastic leukemia in children

A series of 106 fine-needle aspiration biopsy specimens obtained from the testes of children with acute lymphoblastic leukemia was reviewed retrospectively. Involvement by leukemia was seen in 34, there was no evidence of disease in 52, and the cellular sample was inadequate in 20. All aspiration smears, except those with leukemic involvement, showed a variable number of Sertoli cells. Testicular leukemia was diagnosed by the presence of numerous leukemic cells and rare or no Sertoli cells. Fine-needle aspiration biopsy is a simple but effective technique for diagnosing leukemic involvement of the testis in children with acute lymphoblastic leukemia.

Cardiovascular causes of syncope. Identifying and controlling trigger mechanisms

Syncope usually has a cardiovascular source, so neurologic evaluation has a low diagnostic yield in these patients. Cardiac arrhythmias in persons with or without structural heart disease can produce syncope. Neurocardiogenic dysfunction that results in diminished venous return and hypercontractility is another frequent cause. Postural hypotension or left ventricular outflow obstruction may also be to blame. Careful history taking and physical examination, head-up tilt testing, echocardiography or radionuclide isotope imaging, and electrophysiologic study are often diagnostic. However, syncope remains undiagnosed in some patients, and they may require periodic reassessment. Treatment options are available for most cardiovascular disorders, among them use of pharmacologic agents; catheter, surgical, or radio-frequency modification of certain tachycardias; and permanent pacing.

Detection of Escherichia coli cytotoxins by enzyme-linked immunosorbent assays

Sandwich enzyme-linked immunosorbent assays (ELISAs) were developed to detect Escherichia coli cytotoxins. Wells were coated with monoclonal antibodies from hybridomas 13C4 and (or) 11E10, and biotin conjugates of these antibodies were used for detecting verotoxin 1 and Shiga-like toxin II, respectively. Sensitivities were about 100 and 200 cytotoxic doses, respectively. Verotoxin 2 was detected by ELISA with monoclonal antibody 11E10, but at a sensitivity of only about 4000 cytotoxic doses. ELISA results of polymyxin-treated cell extracts from cultures of 67 E. coli strains were in agreement with Vero cell assay as regards the presence and type of toxin.

Fine-needle aspiration biopsy diagnosis of pediatric neoplasms

A series of fine-needle aspiration biopsies performed in 635 children were reviewed. The diagnosis rendered in these patients included malignant lymphoma in 139 (21.9%), Hodgkin's disease, 25 (3.9%); neuroblastoma, 58 (9.1%); Wilms' tumor, 37 (5.8%); Ewing's sarcoma, 32 (5.0%); rhabdomyosarcoma, 25 (3.9%); retinoblastoma, 22 (3.5%); leukemia infiltrate, 33 (5.2%); and miscellaneous tumors, 52 (8.2%). In 171 patients (26.9%), the biopsy was nondiagnostic. The cytomorphological characteristics of these lesions are briefly described and illustrated. Salient morphological features are further correlated with histological and ultrastructural appearances.

Local preparation, standardization and quality control of technetium labelled macroaggregated albumin for lung perfusion studies

Lung perfusion study is an important investigation in various pulmonary diseases. The radiopharmaceutical commonly used now-a- days is imported macroaggregated human albumin (in kit form), which is labelled with technetium (Tc99m-MAA). Due to its high cost the technique could not be fully exploited. We have tried to locally prepare freeze dried MAA particles. Various parameters like concentration of protein, pH value, temperature, quality and quantity of reducing agents were studied to find out the optimum conditions for radiolabelling and the desired particle size. More than 98% of the added radioactivity was found tagged to the MAA particles in the final preparation (confirmed by paper chromatography). Labelled agent was found to be radiochemically stable for up to 6 hours. Initial animal and later human studies showed an ideal spectrum of particle size.

Fine-needle aspiration biopsy of papillary thyroid carcinoma: cytologic, histologic, and ultrastructural correlations

Aspiration smears from a series of 21 papillary thyroid carcinomas were studied and a number of morphologic features correlated with the histologic and ultrastructural patterns. These included types of papillary structures, metaplastic cells, grooved and lobulated nuclei, optically clear nuclei, intranuclear inclusions, and macrophages. Generally there was a close correlation between histologic and cytologic findings. The numbers of macrophages and metaplastic cells appeared to be exaggerated in aspiration smears as compared with those seen on histologic sections. Optically clear nuclei were not seen on the air-dried cytologic smears. Grooved nuclei were somewhat difficult to recognize in the aspiration smears, although lobulated nuclei were identified easily. We consider the latter to be a significant feature in the diagnosis of papillary carcinoma. Ultrastructurally grooved nuclei showed a deep linear indentation of the nuclear membranes. Lobulated nuclei were characterized by multiple indentations that divided the nucleus into several lobules.

Unexplained syncope evaluated by electrophysiologic studies and head-up tilt testing

OBJECTIVE

To determine the clinical characteristics of subgroups of patients with unexplained syncope having electrophysiologic studies and head-up tilt testing and to assess the efficacy of various therapies.

DESIGN

Retrospective study.

SETTING

Inpatient services of a tertiary referral center.

PATIENTS

Eighty-six consecutively referred patients with unexplained syncope.

MEASUREMENTS

All patients had electrophysiologic examinations. Patients with negative results subsequently had head-up tilt testing.

MAIN RESULTS

Twenty-nine (34%) patients (group 1) had abnormal electrophysiologic results, with sustained monomorphic ventricular tachycardia induced in 72%. Thirty-four (40%) patients (group 2) had syncope provoked by head-up tilt testing. The cause of syncope remained unexplained in 23 (26%) patients (group 3). Structural heart disease was present in 76%, 6%, and 30% of groups 1, 2, and 3, respectively. In group 1, pharmacologic or nonpharmacologic therapy was recommended based on electrophysiologic evaluation. All group 2 patients had negative results on head-up tilt testing while receiving oral beta blockers (27 patients) or disopyramide (7 patients). Group 3 patients did not receive any specific therapy. During a median follow-up period of 18.5 months, syncope recurred in 9 (10%) patients.

CONCLUSIONS

The combination of electrophysiologic evaluation and head-up tilt testing can identify the underlying cause of syncope in as many as 74% of patients presenting with unexplained syncope. Therapeutic strategies formulated according to the results of these diagnostic tests appear to prevent syncope effectively in most patients.

Sudden cardiac death: management of high-risk patients

Sudden cardiac death remains a leading cause of death in the United States, accounting for more than 350,000 deaths each year, and the survival rate of victims remains low. Most survivors face a significant risk for recurrence. The typical substrate is chronic--abnormal myocardium with fibrosis (often from previous myocardial infarction) and left ventricular dysfunction. Acute triggers for sudden cardiac death are primarily electrical, ischemic, metabolic, neurohormonal, and pharmacologic. In most electrocardiographically documented cases of sudden cardiac death, the trigger-substrate interaction appears to result in ventricular tachycardia and fibrillation. After initial resuscitation, survivors need a thorough cardiovascular evaluation, including definition of coronary anatomy, left ventricular function, and wall-motion abnormalities, as well as an electrophysiologic evaluation. An attempt must be made to determine what each survivor's correctable triggers are. Management should address all reversible triggers, such as acute ischemia and electrolyte abnormalities, and should include modifying or correcting the arrhythmogenic substrate. Empiric antiarrhythmic therapy offers no advantage in such modification. Pharmacologic therapy with antiarrhythmic drugs should be guided by an objective therapeutic endpoint, which is best accomplished through the use of programmed ventricular stimulation and serial electrophysiologic studies. Other therapeutic options include surgical suppression of ventricular tachycardia and implantation of a cardioverter defibrillator.