An ecological and epidemiological single-season survey of Anaplasma and Ehrlichia positive ticks in Victoria Falls National Park, Zimbabwe.

There is an urgent need for continued research on the ecology of tick-borne diseases in Africa. Our objective was to provide a preliminary description of the ecology and epidemiology of tick species, tick-borne pathogens, and animal hosts in Zimbabwe, focusing efforts at Victoria Falls National Park, for a single season. We tested the hypothesis that tick surveillance and pathogen screening data can be used to model associations among ticks, hosts, and pathogens. We collected ticks from domesticated animals and wildlife in Zimbabwe and screened the ticks for the presence of Anaplasma and Ehrlichia bacteria. Nearly 30% of the screened ticks were PCR-positive; 89% of tick species were PCR-positive, and 88% of animal species carried at least one PCR-positive tick. We sequenced a subset of amplicons that were similar to three Anaplasma species and three Ehrlichia species. The odds of a tick being PCR-positive increased when many ticks were collected from the host or the tick was collected from a cow (domesticated animal). Tick species shared host species more often than expected. We demonstrate that ticks in northwestern Zimbabwe present a One Health problem for nearby wildlife and humans.

Supplemental feeding of deer reduces tick abundance in Mississippi, U.S.A.

Prior research on baiting and feeding of wildlife found changes in habitat and the concentration of wildlife on a local scale (e.g., hundreds of meters). Since changes in habitat and host density affect ticks, feeding wildlife may lead to changes in tick and tick-borne disease ecology. We quantified the effect of feeding deer on ticks and tick-borne diseases at 79 pairs of sites with and without deer feeders during May-August of 2019 and 2020. We captured 0.4 fewer adult (p<0.05) and 1.2 fewer nymphal ticks (p=0.01) at feeder sites. This effect intensified over time with one fewer tick trapped at old feeders (≥5 years) compared to new feeders (<5 years, p<0.05). Greater daily wildlife visitation rates (p<0.001) may have allowed questing ticks to encounter hosts more readily. Most collected ticks were Amblyomma americanum (92.8%), a vector of Ehrlichia and Rickettsia pathogens, though prevalence of these pathogens did not differ (p>0.13) at a local scale. Supplemental deer feeding appears to influence ticks, possibly due to decreased tick habitat and increased wildlife use around feeders. Our findings indicate feeding does not lead to increased prevalence of Ehrlichia or Rickettsia bacteria within A. americanum locally.

Spray and Pour-On Acaricides Killed Tennessee (United States) Field-Collected Haemaphysalis longicornis Nymphs (Acari: Ixodidae) in Laboratory Bioassays.

Haemaphysalis longicornis Neumann (Asian longhorned tick) is an exotic and invasive tick species presenting a health and economic threat to the United States (U.S.) cattle industry due to its ability to transmit pathogens and infest hosts in large numbers. The objective of this study was to evaluate available products at causing H. longicornis mortality in a laboratory bioassay. The efficacy of products was evaluated at label rates using H. longicornis nymphs collected from a cattle farm in eastern Tennessee in two different bioassays (spray or dip) against untreated controls. After exposure, ticks were transferred to clean petri dishes and checked for mortality at 0, 1, 2, 3, 4, 21, 24, and 48 h post exposure. No mortality occurred in the untreated controls, whereas all treated ticks were dead within 24 h of exposure (P < 0.0001). These findings support the hypothesis that currently available spray and pour-on products are effective at causing H. longicornis mortality. We conclude that these acaricides can be used as a component to prevent H. longicornis dispersal and for control in the U.S.

The Common Bed Bug (Hemiptera: Cimicidae) Does Not Commonly Use Canines and Felines as a Host in Low-Income, High-Rise Apartments.

The common bed bug (Cimex lectularius L.) is a known pest and an obligate blood-feeding ectoparasite. Bed bugs can feed on warm-blooded animals including humans, bats, poultry, and rabbits, but no research has investigated the use of companion animals (canines and/or felines) as a blood source. This study investigates how long known host DNA could be detected in a bed bug and the prevalence of bed bugs feeding on companion animals. Laboratory-reared bed bugs were fed host blood to determine how long DNA of human, feline, canine, and rabbit blood could be detected up to 21 d postfeeding. Additionally, 228 bed bugs were collected from 12 apartments with pets (6: canine, 5: feline, and 1: canine and feline), characterized as engorged or unengorged, and then screened with host-specific primers to identify the bloodmeal. Host meals of human, rabbit, feline, and canine blood were detected up to 21 d after feeding laboratory strains. All bed bugs died after feeding on the canine blood, but DNA could be detected up to 21 d post feeding/death. Of the field-collected bed bugs analyzed, human DNA was amplified in 158 (69.3%) bed bugs, canine DNA amplified in 7 bed bugs (3.1%), and feline DNA amplified in 1 bed bug (0.4%). Results of this study suggest that bed bugs predominately feed on humans and rarely feed on companion animals when they cohabitate in low-income, high-rise apartments. Additionally, results from this study warrant future investigations into host use by bed bugs in different housing structures and socioeconomic environments.

Bed Bug (Hemiptera: Cimicidae) Detection in Low-Income, High-Rise Apartments Using Four or Fewer Passive Monitors.

Bed bug, Cimex lectularius L., management in low-income, high-rise housing for the elderly and disabled can be difficult. Early detection is key to slowing their spread, and reducing management cost and time needed for control. To determine the minimum number of passive monitors needed to detect low-level bed bug infestations in this environment, we evaluated three monitors placed one, two, or four per apartment in a 3 by 3 experimental design. One sticky monitor, The Bedbug Detection System, and the two pitfall monitors, ClimbUp Insect Interceptors BG and BlackOut BedBug Detectors, were evaluated. Bed bugs were trapped by the ClimbUp Insect Interceptors BG and the BlackOut BedBug Detector in 88% and 79% of apartments, respectively, but only in 39% of the apartments monitored with The Bedbug Detection System. The Bedbug Detection System required significantly longer time to detect bed bugs than either the ClimbUp Insect Interceptor BG or the BlackOut BedBug Detector. With the less effective Bedbug Detection System data removed from analyses, detection rates ranged from 80 to 90%, with no significant differences among one, two, or four monitors per apartment. Results indicate it is especially important to include a bed placement when only placing a few monitors. Future work should compare the combination of cursory visual inspections with various monitor numbers and placements per apartment to determine the most efficient, cost-effective system that will be accepted and implemented in low-income housing.

Late recurrent saphenofemoral junction reflux after ligation and stripping of the greater saphenous vein.

OBJECTIVE: This study was done to determine the long-term incidence of refluxing epifascial-to-deep vein reconnections in the area of the former saphenofemoral junction after ligation of the true junction, along with all proximal tributaries, and resection of the greater saphenous vein. PATIENTS AND METHODS: A total of 125 limbs in 77 patients, representing 66% of 117 survivors among 602 patients who underwent operation between 1960 and 1967, were evaluated clinically and with duplex sonography for possible superficial-to-deep vein reconnections and clinical recurrence of thigh varicosities at a mean follow-up of 34 years. RESULTS: Clinical examination suggested saphenofemoral recurrence in 59 limbs (47%). In 11 instances these were actually varices associated with isolated superficial system reflux or reflux originating from a distally located perforating vein. Color-coded duplex ultrasonography demonstrated saphenofemoral reflux in 75 limbs (60%), versus the 48 identified on clinical examination (P <.001), and documented that the junction ligation had not been performed incorrectly by absence of the terminal valve or any patent proximal saphenous remnant. The reflux originated at the site of the ligated saphenofemoral junction in 53 limbs (71%) and from a nearby circumjunctional deep vein in the other 22 (29%). Of the real junctional recurrences, 22 appeared as a tangled cluster, and 31 involved a single-lumen varix. Only 27 recurrences were sufficiently symptomatic to warrant consideration of additional treatment; 25 of these were clinically evident, single-lumen, true junctional recurrences. CONCLUSIONS: This 34-year clinical follow-up study shows a 60% incidence of junctional and circumjunctional reconnections after ligation of the true saphenofemoral junction and its related tributaries. Color-coded duplex sonography is a necessary concomitant to clinical examination, detecting more recurrences and defining the pathologic anatomy to direct clinically indicated additional treatments.

Survey of laparoscopic entry injuries provoking litigation.

STUDY OBJECTIVE: To examine injuries sustained during laparoscopic entry procedures that provoked malpractice claims in order to discern relative vulnerability of specific organs and differences in injury patterns, mortality, and financial awards, and specific entry devices involved in domestic claims versus those in other countries. DESIGN: Survey (Canadian Task Force classification II-2). SETTING: Insurance company records. INTERVENTIONS: Abstracts of malpractice allegations in 135 domestic cases insured by United States member companies of the Physician Insurers Association of America and 111 cases by its non-United States affiliates were examined. MEASUREMENTS AND MAIN RESULTS: Most cases in the United States involved biliary-gastrointestinal surgery rather than gynecologic procedures; this was reversed for the non-United States database. Major vessel injury was proportionally more common in the domestic group. Small bowel led the group of structures injured. Most injuries involved trocars of various types (185), including blunt types (16); and needle injuries were noted in 39 cases. Injuries were recognized more immediately in the United States, and mortality was related to delay in diagnosis of bowel penetration. Indemnity payments were greater for serious nonfatal injuries versus deaths in the United States, but the opposite was true in other countries. CONCLUSION: Probably no needle-trocar system can guarantee avoidance of injury during laparoscopic entry, especially when the trajectory of insertion puts great vessels at risk. Bowel injuries occur during open as well as closed techniques of insertion, and with optical trocar systems as well. Vascular injury is usually obvious, but delayed recognition of loss of bowel integrity is related to increased mortality, especially in patients over 60 years of age.

Three spectra of laparoscopic entry access injuries.

BACKGROUND: Procedure-based surveys oflaparoscopic entry access injuries show a reassuringly low incidence, varying from 5 per 10,000 to 3 per 1,000, and, consequently, can provide only limited specific injury data. The current study uses existing injury-based reporting systems to access a uniquely large number of entry injuries to define the nature and outcomes of such events. STUDY DESIGN: Claims arising from US and non-US entry access injuries, between 1980 and 1999, reported to the Physicians Insurers Association of America by their member and affiliate companies and entry-injury medical device reports to the US FDA, from 1995 through October 1997, were analyzed to determine operative procedures, physician specialties, entry devices, and techniques associated with specific injuries. Individual injuries were analyzed for their relative incidence and potential to cause disability and death. RESULTS: Five hundred ninety-four structures or organs were injured in 506 patients, resulting in 65 deaths (13%). General surgical procedures made up at least 67% of combined medical device reports and US Physicians Insurers Association of America cases, and gynecologic procedures accounted for 63% of non-US claims. Bowel and retroperitoneal vascular injuries comprised 76% of all injuries incurred in the process of establishing a primary port. Nearly 50% of both small and large bowel injuries were unrecognized for 24 hours or longer. Delayed recognition, along with age greater than 59 years and major visceral vascular injuries, were each independent significant predictors of death. CONCLUSIONS: No entry technique or device is absolutely safe. Avoidance of entry injuries depends on patient-specific anatomic orientation and control of entry axial force. Certain entry devices can be facilitating in controlling axial force. Overall, this large aggregate of entry access injuries shows them to be more serious and, along with other data, implies that they might be more common than reported in procedure-based studies.

Defining the role of extended saphenofemoral junction ligation: a prospective comparative study.

OBJECTIVE: This study explores the added effect of extended saphenofemoral junction (SFJ) ligation when the greater saphenous vein (GSV) has been eliminated from participating in thigh reflux by means of endovenous obliteration. GSV obliteration, unlike surgical stripping, can be done with or without SFJ ligation to isolate and study SFJ ligation's specific contribution to treatment results. METHODS: Sixty limbs treated with SFJ ligation and 120 limbs treated without high ligation were selected from an ongoing, multicenter, endovenous obliteration trial on the basis of their having primary varicose veins, GSV reflux, and early treatment dates. RESULTS: Five (8%) high-ligation limbs and seven (6%) limbs without high ligation with patent veins at 6 weeks or less were excluded as unsuccessful obliterations. Treatment significantly reduced symptoms and CEAP clinical class in both groups (P =.0001). Recurrent reflux developed in one (2%) of 49 high-ligation limbs and eight (8%) of 97 limbs without high ligation by 6 months (P =.273). New instances of reflux did not appear thereafter in 57 limbs followed to 12 months. Recurrent varicose veins occurred in three high-ligation limbs and four limbs without high ligation by 6 months and in one additional high-ligation limb and two additional limbs without high ligation by 12 months. Actuarial recurrence curves were not statistically different with or without SFJ ligation (P >.156), predicting greater than 90% freedom from recurrent reflux and varicosities at 1 year for both groups. CONCLUSION: These early results suggest that extended SFJ ligation may add little to effective GSV obliteration, but our findings are not sufficiently robust to warrant abandonment of SFJ ligation as currently practiced in the management of primary varicose veins associated with GSV vein reflux.

Endovenous management of saphenous vein reflux. Endovenous Reflux Management Study Group.

PURPOSE: This study assessed clinical outcomes of two catheter-based endovenous procedures to eliminate or greatly mitigate saphenous vein reflux. MATERIALS AND METHODS: A computer-controlled, dedicated generator and two catheter designs were used to treat 210 patients at 16 private clinic and university centers in Europe. The Closure catheter applied resistive heating over long vein lengths to cause maximum wall contraction for permanent obliteration; the Restore catheter induced a short subvalvular constriction to improve the competence of mobile but nonmeeting leaflets. RESULTS: Closure treatment caused acute obliteration in 141 (93%) of 151 limbs; Restore treatment, shrinking one or more valves, acutely reduced reflux to less than 1 second in 41 (60%) of 68 limbs. Closure treatments were associated with early recanalization (6%), paresthesias (thigh, 9%; leg, 51%; P <.001), 3 skin burns, and 3 deep-vein thrombus extensions, with 1 embolism. Restore treatments were thrombogenic (16%) despite prophylactic anticoagulation, and treated valves enlarged over 6 weeks, becoming less competent. Clinical Efficacy Assessment Project clinical class was significantly improved after both treatments, up to 1 year. At 6 months, 87% of 53 Closure patients were class 0 or 1, 75% were symptom-free, and 96% of 55 treated limbs were completely free of reflux. Fourteen of 31 Restore patients (45%) had no symptoms, but 55% were class 2 or lower and only 19% had less than 1-second reflux. CONCLUSION: Closure treatment is clinically effective, albeit with offsetting complications and early failures; these are being addressed through four procedural modifications. Restore valve shrinking, although conceptually attractive, is too problematic to be competitive with Closure treatment or saphenectomy.

Role of duplex imaging in endovenous obliteration for primary venous insufficiency.

PURPOSE: To assess the role of duplex imaging in defining suitable pathological anatomy for endovenous obliteration and characterizing its treatment outcomes over time. METHODS: Eighteen lower limbs in 17 patients (12 women; mean age 48 years; range 29-74 years) presenting with varicose greater saphenous veins (GSVs) were treated with endovenous obliteration without adjunctive high ligation. Duplex imaging was used as an intraprocedural guidance tool for vein access and catheter positioning and for preprocedural evaluation and serial surveillance after the procedures. RESULTS: In the 18 limbs, preprocedural duplex scanning defined reflux owing to incompetence of the terminal valve (n = 6), subterminal valve (n = 9), or truncal valve (n = 3). Duplex imaging facilitated percutaneous vein puncture and was essential in catheter positioning at the saphenofemoral junction (SFJ). At 1 week, the saphenous trunks of all 18 limbs were either shrunken and obliterated (n = 7) or occluded by thrombus without shrinkage (n = 11). By 6 months, 7 GSVs were no longer sonographically visible, 10 were shrunken and obliterated, and 1 had a segmental partial recanalization. In the 15 limbs with terminal or subterminal valve incompetence at 1 week, 5 had total SFJ obliteration, 4 had > or =1 patent tributaries draining directly into the femoral vein through an open SFJ, and 6 had > or =1 patent tributaries draining into an open SFJ through a short (<2 cm) proximal saphenous trunk. By 6 months, only 1 limb had total SFJ occlusion; the other 14 had at least 1 persistent or reopened tributary. CONCLUSIONS: Duplex scanning is indispensable for selecting patients, guiding the procedure, and defining the morphological maturation and hemodynamic changes that appear to characterize successful endovenous obliteration.

Strut fracture mechanisms of the Björk-Shiley convexo-concave heart valve.

Investigations of convexo-concave (C/C) valve outlet strut fractures (OSFs) were initially confounded by knowledge that the strut was subject to bending forces in arresting the opening disc. Pulse duplicator studies subsequently showed that closing loads were all born by the inlet strut, along with an understandable focus on the nature of the welds, where most fractures occurred. As observations of explanted valves accumulated, certain features pointed to unusual closing loads that might be contributory factors, but these hypothetical forces could not be verified. Epidemiological extrapolations and case-matched control studies have shown that certain valve and patient characteristics were each associated independently with increased OSF risk, leading to clinically valuable risk stratification, but little additional understanding of why OSFs continued to occur. Detection of the causative, highly transient (< 0.5 ms), outlet-strut-tip impacts due to closing disc over-rotation that have almost ten times the force of disc opening, and the capability of inducing leg-base bending stresses beyond the strut wire's fatigue endurance limit had to await the development of computer-controlled pulse duplicators and strut-leg strain gaging. Exercised young animals easily achieved such strut loading, but most human patients would probably have more difficulty. The actual OSF mechanism is a long-term, valve-patient interaction that requires the concurrence of susceptible valve geometry and sufficient ventricular contractility potential to develop the isovolumic, high dP/dt needed for forceful disc over-rotation. Critical strut tip loading must then occur often enough to fatigue fracture both strut legs within the patient's lifetime with the valve.

Welding metallurgy's putative influence on Björk-Shiley convexo-concave valve outlet strut failures.

BACKGROUND AND AIM OF THE STUDY: Multiple reports of convexo-concave valve outlet strut fractures have focused on the welds, often implicating putative defects of uncertain character and significance. This study differs from all others in that it systematically assesses a large number (n = 60) of intact and fractured valves and clearly differentiates findings on the critical, tensile-stressed, inflow side of the outlet strut leg from those on the outflow side, which are subject only to compression. METHODS: Each valve was examined by scanning electron microscopy and subjected to multiple metallographic sectioning of each strut-flange interface. All fractures and selected intact valves were further analyzed with X-ray dispersive spectroscopy. RESULTS: Fatigue striations were seen in all fractured valves, and their orientation indicated that every fracture initiated in an area on the inflow side, spreading out progressively towards the outflow side. Data indicated that 22% of the first-to-fail leg separations and 17% of all fractures initiated outside of the weld. Element segregation areas were seen in 40% of welds, significantly more commonly in intact valves, invariably located on the outflow side, and typically (85%) apart from the fracture path. Microporosity was identified in 15% of welds, usually near the outflow side, and in the same proportion of intact and fractured valves. One fracture surface had a 38 microns, inflow-side void that might have been a factor in crack initiation in this valve, which was highly stressed. CONCLUSIONS: With this singular exception, no metallurgical feature of any weld was found that appeared to have contributed, even in a minor way, to the process of outlet fracture.

High-burst-strength, feedback-controlled bipolar vessel sealing.

BACKGROUND: The inherent tedium of intracorporeal knot tying has stimulated greater interest in energy-based and mechanical alternatives for hemostasis. METHODS: Three hundred thirty-one arteries and veins were sealed by application of precisely controlled electrothermal energy and physical pressure, allowing for brief cooling in compression, in experimental animals and fresh abattoir vessels. These seals were compared for bursting strength with occlusions by ultrasonic and bipolar coagulation, surgical clips, and ligatures. RESULTS: Ultrasonic and bipolar occlusions were significantly less likely to have burst strengths greater than 400 mmHg as compared with seals, clips, and ligatures (p < 0.001). Seal competence could be visually assessed by its translucence. CONCLUSIONS: Precise energy control with physical compression, including a brief cooldown, produces a distinctive, translucent seal of partially denatured protein that can typically be transected after a single application. These seals have bursting strengths comparable to those of clips and ligatures and resist dislodgement because they are intrinsic to the vessel wall structure.

In vivo accuracy of two radiographic systems in the detection of Björk-Shiley convexo-concave heart valve outlet strut single leg separations.

OBJECTIVE: Modified cineradiographic systems have been used clinically to detect partially broken outlet struts in normally functioning Björk-Shiley convexo-concave heart valves. Almost all such valves were explanted, presuming that full failure would likely follow. Inasmuch as the clinical setting only rarely permits examination of normally rated valves, the accuracy of radiographic detection cannot be clinically defined. This study uses the clinical radiographic technique in sheep implanted with known-status convexo-concave valves, comparing its accuracy and that of a newly developed, geometric image magnification radiography system. METHODS: Twenty-one sheep with mitral convexo-concave valves were studied on both systems. Five were used for extensive training. When operators were expert with both systems, images of four intact valves and 12 valves with outlet strut single leg separations, along with a seventeenth single leg separation valve used for calibration, were integrated into 112 image sets organized into a balanced incomplete block design for evaluation by eight trained, blinded reviewers. RESULTS: Cineradiography sensitivity was 24% versus 31% for direct image magnification. The odds ratio for detection of single leg separation by direct image magnification versus cineradiography was 2.0 (95% confidence interval, 0.76 to 5.9; p = 0.13). Cineradiography specificity was 93% versus 90% for direct image magnification. Sensitivity and specificity varied markedly by reviewer, with sensitivity ranging from 8% to 55% and specificity from 51% to 100% for the combined technologies. CONCLUSIONS: The data support the need for more intensive training for convexo-concave valve imaging and further investigation of unconventional radiographic technologies. Clinical cineradiography of convexo-concave valves may detect as little as 25% of valves having a single leg separation, underestimating the prevalence of single leg separations and thereby implying more rapid progression to full fracture than is actually the case.

Thermoregulated radiofrequency endometrial ablation.

OBJECTIVE: To test the hypothesis that treating dysfunctional uterine bleeding by automated application of electrothermal energy to the uterine cavity, with precise regional control, might yield results equivalent to those reported for hysteroscopically directed laser and electrosurgical endometrial ablations. MATERIALS AND METHODS: Patients with life style compromising menorrhagia, referred to six gynecologic surgical centers for hysterectomy or endometrial ablation, were admitted to the study if they had normal cervical cytology, a benign endometrial biopsy, no defined cause for their bleeding, and consented to participate in the evaluation of a newly developed Vesta DUB Treatment System. The device consists of a silicone-inflatable electrode carrier to be inserted into the uterine cavity and a controller to monitor and distribute current from a matched electrosurgical generator. Treatment involved a 3-minute or shorter warm-up period and a 4-minute treatment phase. RESULTS: Three- to 24-month follow-up data were available for 187 patients, with a mean follow-up of 14.8 months. The amenorrhea rate was 38%. Bleeding was reduced in 95% of patients. Actuarially, 88 +/- 3% of patients should expect to be free of menorrhagia, dissatisfaction, or need for a second procedure out to 24 months. CONCLUSIONS: The unique regional feed-back control offered by this system causes thorough, evenly distributed, thermal destruction 4-5 mm into the myometrium that reduces bleeding with durability equivalent to published reports of hysteroscopic endometrial ablation.

Litigious consequences of open and laparoscopic biliary surgical mishaps.

Three hundred six injuries or complications coincident to 296 laparoscopic cholecystectomies were analyzed for the nature and extent of injuries and litigious outcomes that followed. The data were drawn from 31 member companies of the Physician Insurers Association of America, a trade association that initiated the study. The outcomes were compared to 261 contemporaneous open cholecystectomy claims. Biliary tract injuries were the most common, accounting for almost two thirds of all injuries. The spectrum of cases, originally selected for indemnity potential, reflected relative incidences in the medical literature. Laparoscopic injuries were significantly more severe, more likely to result in indemnity, and more apt to involve higher mean +/- standard deviation dollar values (160 dollars +/- 154 x 10(3)) to surviving claimants than injuries resulting from open procedures (106 dollars +/- 122 x 10(3), P = 0.01). Injury recognition at the time of the original procedure had no discernible mitigating effect because 80% of recognized injuries required an additional operative procedure. Risk-aversive behavior should include paying particular attention to placement of the first port, more liberal use of the Hasson technique, placement of all other ports under direct vision, elimination of intraoperative anatomic uncertainty, programmed inspection of the abdomen before withdrawing the laparoscope, and acquiring sufficient knowledge of electrosurgical principles to ensure the safe use of this potentially dangerous modality.

Acoustic assessment of the physical integrity of Björk-Shiley convexo-concave heart valves.

BACKGROUND: Several lines of evidence indicate a two-stage failure mode for the Björk-Shiley convexo-concave (C/C) heart valve, in which one of the two outlet strut legs separates from the flange before the other, potentially providing an opportunity to identify and prophylactically replace failure-prone valves. Radiographic single leg separation (SLS) detection, although successful, is subjective and skill intensive, implying a need for both an objective preliminary screen and subsequent corroboration of the radiographic findings. METHODS AND RESULTS: We developed a time-windowed, power density analysis of C/C valve closing sounds to detect the vibrational resonance that characterizes the presence of an intact outlet strut in clinically functioning, 29-mm-flange size C/C valves. Recordings from more than 800 patients enrolled in radiographic SLS detection studies were analyzed, and the assessment algorithm was evaluated through a blinded test of 32 study valves for which the true status became known consequent to an autopsy or surgical explantation. Valves were objectively scored on a 0-to- 1 scale, with 1 being assuredly intact and scores of < 0.50 indicating a probable SLS. All except five valves (incorrectly designated probable SLS) were classified correctly, for a sensitivity of 1.00 (95% confidence interval, 0.79 to 1.00) and a specificity of 0.69 (0.41 to 0.89). CONCLUSIONS: This level of accuracy is sufficient to serve as an effective preliminary screen, potentially allowing a threefold concentration of SLS prevalence among the C/C valves of patients undergoing radiographic assessment. The value of acoustic classification in avoiding unnecessary operations prompted by false-positive radiographs is less certain.

Radiographic detection of single strut leg separations as a putative basis for prophylactic explantation of Björk-Shiley convexo-concave heart valves.

Cineradiography, using higher kVp and two or more specified profiles for each outlet strut leg, was used to evaluate Björk-Shiley convexo-concave (C/C) heart valves with epidemiologically defined > 0.1% per year estimated fracture rates. Among 828 mitral valves, eight radiographs were assessed as definite single leg separations (SLS) and 23 were read as probable SLS. Explantation confirmed SLS in 24 valves; 4 probables were false positives, and 3 patients with probable SLS ratings decided against explantation. Four patients with SLS died, an operative mortality of 14%. Only 23 mitral and 6 aortic valves receiving ratings ranging from apparently normal to suspicious have become available for verification; 1 rated apparently normal was found to have a SLS. Two patients experienced fatal fractures and 1 SLS valve was explanted 3 to 15 months after apparently normal x-ray studies; it cannot be known if a SLS was or was not present at the time of these examinations. As 97% of negatively rated valves remain in situ, the sensitivity of the test is similarly not known. Only 1 SLS has been detected among 136 aortic valves. Uncertainty about test accuracy and SLS progression condition the clinical utility of radiographic SLS detection, particularly with respect to assurance from apparently normal readings. However, radiographic identification of an SLS substantially enhances epidemiologically derived risk categorization as a basis for consideration of prophylactic replacement for the approximately 12,000 valves with a > 0.1% estimated annual fracture risk, currently thought to be implanted in living patients.

A working cardiac valve phantom for radiographic assessment of prosthetic heart valves.

RATIONALE AND OBJECTIVES: A working valve phantom (WVP) that both exercises the valve occluder and simulates movements of the mitral annulus is described. It was designed to develop a method for radiographic detection of a single broken leg of the two-legged Björk-Shiley convexo-concave (C/C) heart valve outlet strut. METHODS: The WVP consists of a pneumatically driven left ventricular assist device immersed in 22 cm of water. Left ventricular assist device annulus movements are generated by systolic turgor and diastolic relaxation of the aortic outflow graft within limits set by the holding fixture design. RESULTS: WVP images were comparable in attenuation, valve motion, and diagnostic sensitivity to clinical C/C valve images and were effective in assessing leaflet excursions in another valve model. Techniques developed in the WVP have proved successful in the clinical detection of C/C valves that have a single broken leg but that show normal function in all other tests. CONCLUSION: The WVP can be a useful tool for developing refined radiographic assessments of prosthetic heart valves.