Prevalence of pannus formation after aortic valve replacement: clinical aspects and surgical management

Pannus formation after aortic valve replacement is not common, but obstruction due to chronic pannus is one of the most serious complications of valve replacement. The causes of pannus formation are still unknown and effective preventive methods have not been fully elucidated. We reviewed our clinical experience of all patients who underwent reoperation for prosthetic aortic valve obstruction due to pannus formation between 1973 and 2004. We compared the initial 18-year period of surgery, when the Björk–Shiley tilting-disk valve was used, and the subsequent 13-year period of surgery, when the St. Jude Medical valve was used. Seven of a total of 390 patients (1.8%) required reoperation for prosthetic aortic valve obstruction due to pannus formation. All seven patients were women; four patients underwent resection of the pannus and three patients needed replacement of the valve. The frequency of pannus formation in the early group was 2.4% (6/253), whereas it was 0.73% (1/137) in the late group (P < 0.05). Pannus was localized at the minor orifice of the Björk–Shiley valve in the early group and turbulent transvalvular blood flow was considered to be one of the important factors triggering its growth. We also consider that small bileaflet valves have the possibility of promoting pannus formation and that the implantation of a larger prosthesis can contribute to reducing the occurrence of pannus.     

Pannus formation in aortic valve prostheses in the late postoperative period

We present three patients who underwent repeat aortic valve replacement for prosthetic valve dysfunction caused by tissue ingrowth in the late postoperative period. These patients (three women aged 48–51 years, mean 49.3 ± 1.53 years) underwent operations for restriction of prosthetic valve leaflet movement by pannus in the left ventricular outflow tract. The interval from the previous operation ranged from 8.0 to 9.6 years (mean 9.6 ± 2.0 years). The symptoms of the patients were New York Heart Association functional class I, II, and IV in one patient each. Diagnosis was made by cinefluoroscopy in two patients and aortography in one patient. The operative procedures consisted of aortic valve replacement (n = 1) and aortic valve replacement with mitral valve replacement (n = 2). Pannus was found at the left ventricular aspect of the prosthetic valve in all patients. In two patients, the pannus directly restricted movement of the leaflet and also severely narrowed the inflow orifice of the prosthetic valve. In the other patient, the pannus had grown at a distance of 7mm from the valve and narrowed the left ventricular outflow tract circularly. The postoperative course was uneventful and all three patients were discharged in a good condition. One patient died of pneumonia 8 months after surgery and the other two patients have remained well and have been followed up for one and a half years. In conclusion, there may be a discrepancy between the clinical symptoms and the grade of subvalvular stenosis caused by pannus. Therefore, it is essential for satisfactory operative results that early diagnosis be made by various means.     

A SAM valve prosthesis in the mitral position: report of a case of long-term survival

No long-term survivals over 20 years after valve replacement with SAM (Sakakibara-Arai-Mera) valve prostheses have been described. We report a 57-year-old woman who survived for 31 years after mitral valve replacement with the SAM valve (Type M, 5M). Echocardiography revealed remarkable dilatation of the left atrium and moderate tricuspid regurgitation. Cineradiography, however, showed no restricted or asymmetric disc movement of the SAM valve. Cardiac catheterization revealed moderate pulmonary hypertension (64/30mmHg), with a mean pulmonary capillary wedge pressure of 25mmHg and a mean transprosthetic pressure gradient of 13mmHg. The mitral valve area was calculated to be 0.9 cm². No findings of pannus overgrowth around the SAM valve were confirmed on echocardiograms or left ventriculograms. Although the diagnosis of prosthetic valve obstruction resulting from pannus formation was suspected, the patient strongly refused replacement of the SAM valve because of her poor prognosis with bilateral breast cancer with systemic metastases. We believe that this patient may be the last living patient with the SAM valve.     

Observation of cavitation pits on a mechanical heart valve surface in an artificial heart used in in vivo testing

The aim of this study was to observe mechanical heart valve (MHV) cavitation pits resulting from in vivo testing of an electrohydraulic total artificial heart (EHTAH). During in vivo testing with three sets of valves (one set used in two animals), the slope of the driving pressure (left and right driving pressure) was used as a factor for investigating cavitation intensity, and the occurrence of cavitation was determined by the observation of cavitation pits on the explanted valve surfaces. Medtronic Hall valves were installed at the inlet and outlet positions of the two blood pumps. The EHTAH was tested using calves weighing 69–80 kg. The cavitation pits on the valve surface of the inlet valves of the left and right blood pumps were examined by scanning electron micrography. The driving pressure slope 5 ms before valve closure exceeded the cavitation threshold during in vitro testing. On both inlet valves, many large pits formed when the driving pressure slope was high and the pump operating time was long. When estimating cavitation intensity during in vivo testing, both a high driving pressure slope and a long operating time are important factors. The cavitation pits observed on the valve surfaces resulting from in vivo testing will eventually lead to leaflet fracture.     

心脏瓣膜术联合冠状动脉旁路移植术治疗心脏瓣膜疾病患者的临床价值研究

目的:分析心脏瓣膜术联合冠状动脉旁路移植术治疗心脏瓣膜疾病患者的临床价值.方法:选取我院于2017年5月至2019年5月期间收治的80例心脏瓣膜病患者为研究对象,随机分为研究组和对照组,各40例.对比两组术后相关指标情况、手术前后心功能指标.结果:研究组呼吸机辅助通气时间、ICU监护时间以及住院时间均短于对照组(P<0...     

Characteristics of cavitation intensity in a mechanical heart valve using a pulsatile device: synchronized analysis between visual images and pressure signals

To investigate the characteristics of cavitation intensity, we performed a synchronized analysis of the visual images of cavitation and the pressure signals using a pulsatile device. The pulsatile device employed was a pneumatic ventricular assist device (PVAD) that is currently being developed by our group. A 23-mm Medtronic Hall valve (M-H valve) and a 23-mm Sorin Bicarbon bileaflet valve (S-B valve) were mounted in the inlet port of the PVAD after the sewing ring had been removed. A function generator provided a square signal, which was used as the trigger signal, via Electrocardiogram R wave (ECG-R) mode, of the control - drive console for circulatory support. The square signal was also used, after a suitable delay, to synchronize operation of a pressure sensor and a high-speed video camera. The data were stored using a digital oscilloscope at a 1-MHz sampling rate, and then the pressure signal was band-pass filtered between 35 and 200 kHz using a digital filter. The valve-closing velocity, visual cavitation time, and root mean square (RMS) pressure of the M-H valve were greater than those of the S-B valve. Both the visual cavitation time and RMS pressure represent the cavitation intensity, and this is a very important factor when estimating mechanical heart valve cavitation intensity in an artificial heart.     

Closing behavior of the mechanical heart valve in a total artificial heart

Recently, cavitation on the surface of mechanical heart valves has been studied as a cause of fractures occurring in implanted mechanical heart valves. The cause of cavitation in mechanical heart valve was investigated in both 25-mm Björk–Shiley and 25-mm Medtronic Hall valves. The closing events of these valves in the mitral position were simulated in an electrohydraulic total artificial heart with a stroke volume of 85?ml. The tests were conducted under physiologic pressures at heart rates of 60, 70, 80, and 90 beats/min with cardiac outputs of 4.5, 5.5, 6.4, and 7.5?l/min, respectively. The disk closing behavior was measured by a laser displacement sensor. The closing behaviors were investigated under various atrial and aortic pressures. In both valves, the duration of closing decreased with an increase in the cardiac output. The greater the amount of atrial pressure, the shorter the closing duration of both valves. The maximum closing velocity of the Medtronic Hall monostrut valve ranged from 0.8 to 0.9?m/s, and that of the Björk–Shiley monostrut valve ranged from 0.73 to 0.78?m/s. In both valves, the maximum closing velocities were less than the reported cavitation thresholds. This suggests that there should be no possibility of occurrence of cavitation in an electrohydraulic total artificial heart with mechanical heart valve.     

Effects of mechanical valve orifice direction on the flow pattern in a ventricular assist device

We have been developing a pneumatic ventricular assist device (PVAD) system consisting of a diaphragm-type blood pump. The objective of the present study was to evaluate the flow pattern inside the PVAD, which may greatly affect thrombus formation, with respect to the inflow valve-mount orientation. To analyze the change of flow behavior caused by the orifice direction (OD) of the valve, the flow pattern in this pump was visualized. Particle image velocimetry was used as a measurement technique to visualize the flow dynamics. A monoleaflet mechanical valve was mounted in the inlet and outlet ports of the PVAD, which was connected to a mock circulatory loop tester. The OD of the inlet valve was set at six different angles (OD = 0°, 45°, 90°, 135°, 180°, and 270°, where the OD opening toward the diaphragm was defined as 0°) and the pump rate was fixed at 80 bpm to create a 5.0 l/min flow rate. The main circular flow in the blood pump was affected by the OD of the inlet valve. The observed regional flow velocity was relatively low in the area between the inlet and outlet port roots, and was lowest at an OD of 90°. In contrast, the regional flow velocity in this area was highest at an OD of 135°. The OD is an important factor in optimizing the flow condition in our PVAD in terms of preventing flow stagnation, and the best flow behavior was realized at an OD of 135°.     

Dynamics of a mechanical monoleaflet heart valve prosthesis in the closing phase: Effect of squeeze film

An analysis of the dynamics of a mechanical monoleaflet heart valve prosthesis in the closing phase is presented. The backflow velocity of the fluid and the pressure distribution on the occluder during the closing phase were computed using a control volume approach in the unsteady state. Using moment equilibrium principles on the occluder motion and the squeeze film dynamics of the fluid between the occluder and the guiding strut at the instant of impact, the velocity of the occluder tip and the impact force between the occluder and the guiding struts were computed. The dynamics of fluid being squeezed between the occluder and the guiding struts are accounted for by Reynolds' equation. The effect of the fluid being squeezed between the occluder and the guiding strut was to reduce the velocity of the occluder tip at the instant of valve closure as well as to dampen the fluttering of the occluder before coming to rest in the fully closed position. The squeeze film fluid pressure changed rapidly from a high positive value (10 MPa) to a relatively large negative value (−15 MPa) in <1 msec. The results of this study may be extended for the analysis of cavitation inception and mechanical stresses on the formed elements and valve components, as well as to estimate the endurance limits of prosthetic valves.     

Relationship between the membranous septum and the virtual basal ring of the aortic root in candidates for transcatheter implantation of the aortic valve

Knowledge of the anatomy of the membranous septum, as a surrogate to the location of the atrioventricular conduction axis, is a prerequisite for those undertaking transcatheter implantation of the aortic valve (TAVI). Equally important is its relationship of the virtual basal ring. This feature, however, has yet to be adequately described in the living heart. We analyzed computed tomographic angiographic datasets from 107 candidates (84.1 ± 5.2 years, 68% women) for TAVI. Using multiplanar reconstructions, we measured the height and width of the membranous septum, and the distances of its superior and inferior margins from the virtual basal ring plane. We also assessed the extent of wedging of the aortic root between the mitral valve and the ventricular septum. Mean heights and widths of the membranous septum were 6.6 ± 2.0, and 10.2 ± 3.1 mm, respectively, with its size significantly associated with that of the aortic root (P < 0.05). Its superior and inferior margins were 4.5 ± 2.3 and 2.1 ± 2.1 mm, respectively, from the plane of the basal ring. The inferior distance, the surrogate for the adjacency of the atrioventricular conduction axis, was ≤ 5mm in 91% of the patients. Deeper wedging of the aortic root was independently correlated with a shorter inferior distance (β = 0.0569, P = 0.0258). The membranous septum is appreciably closer to the virtual basal ring than previously appreciated. These findings impact on estimations of the risk of damage to the atrioventricular conduction axis during TAVI. Clin. Anat. 31:525–534, 2018. © 2018 Wiley Periodicals, Inc.     

The first documented case of Aspergillus cardiac surgical site infection in Sweden: an epidemiology study using arbitrarily primed PCR

Bergman A, Lignell A, Melhus Å. The first documented case of Aspergillus cardiac surgical site infection in Sweden: an epidemiology study using arbitrarily primed PCR. APMIS 2009; 117: 568–74. Here we report two rare cases of severe thoracic Aspergillus fumigatus infections after lung and heart surgery at the same thoracic intensive care unit at the same time. The main objective was to identify a possible source of transmission. With arbitrarily primed polymerase chain reaction a patient‐to‐patient transmission could rapidly be ruled out as the cause of the first documented case of aspergillosis after open‐heart surgery in Sweden. Although no definitive source was identified, a genetically similar strain was found in a contaminated supply room.     

Isolated infective endocarditis of the pulmonary valve: an autopsy analysis of nine cases

IntroductionInfective endocarditis (IE) of the pulmonary valve is uncommon and usually occurs in conjunction with tricuspid and/or left-sided valvular endocarditis. There have been only sporadic reports of isolated pulmonary valvular infective endocarditis (PVIE). This report documents the pathological features of nine such cases at autopsy.MethodsAmong 155 cases of IE encountered in a 14-year period, we selected nine cases that had isolated PVIE for analysis. The clinical records were reviewed for the patient demographics, presence or absence of underlying cardiac disease or other predisposing factors, and modes of presentation; these were correlated with the relevant investigations. A detailed study of the heart was done in all with special attention to the pulmonary valve morphology.ResultsThe nine cases of isolated PVIE formed 5.8% of the IE cases, seen in six males and three females, largely adults. Seven patients (77.8%) had admissions for about 24 h. Hospital admission was sought for mainly progressive shortness of breath (66.7%) and fever (44.4%). Congenital heart disease was seen in seven (77.8%); two (an infant and an adult) had normal hearts. A single blood sample for blood culture in two patients was negative. Two-dimensional echocardiography, performed in eight, revealed vegetations on the pulmonary valve in four. The pulmonary valve was tricuspid in six cases, bicuspid in two, and unicuspid in one. The vegetations (active in three, active and healing in two, healed in four) were accompanied by concomitant thickening, shortening, perforations, or complete destruction of the cusps. Involvement of the right ventricular outflow tract or the main pulmonary artery was identified in five hearts. Five patients (55.6%) developed pulmonary complications, related to the endocarditis.ConclusionsDetection of PVIE, especially the isolated type, may be underdiagnosed. This condition should be kept in mind during evaluation of patients especially with cardiac anomalies, who present with fever, prominent respiratory symptoms, and negative blood cultures.     

Incidental in vivo detection of an epithelioid hemangioendothelioma of the mitral valve

Valvular epithelioid hemangioendotheliomas (EHE) are exceptional. To the authors' knowledge only four cases have been reported. Herein is described an EHE incidentally detected in the mitral valve of a 69-year-old woman with chronic rheumatic valvular heart disease. The 0.4 cm lesion was situated in the anterior leaflet and was discovered in the pathological study after mitral valve replacement. The patient was alive and well 6 months after operation. Review of the literature including the present report, revealed that the mean age was 60.2 years (range, 49-69 years). Symptomatic patients had clinical features of valvular disease or embolism. Each of the four cardiac valves can be affected. Mean tumor size was 2.4 cm (range, 0.4-8 cm). In 40% of cases the EHE was an incidental finding at autopsy or in a removed valve. In two cases the involved cusp was affected by chronic rheumatic disease. In conclusion, EHE is a rare lesion that can be an incidental finding and it should be considered in the differential diagnosis of valve tumors. Although EHE can present a histologically benign appearance, the correct pathological diagnosis is clinically important because the lesion can be potentially malignant. Regular follow up is suggested due to this potential.     

Pulmonary disease caused by Mycobacterium xenopi: the first case in Korea

Mycobacterium xenopi is a nontuberculous mycobacterium (NTM) that rarely causes pulmonary disease in Asia. Here we describe the first case of M. xenopi pulmonary disease in Korea. A 66-year-old man was admitted to our hospital with a 2-month history of productive cough and hemoptysis. His past medical history included pulmonary tuberculosis 44 years earlier, leading to a right upper lobectomy. Chest X-ray upon admission revealed cavitary consolidation involving the entire right lung. Numerous acid-fast bacilli were seen in his initial sputum, and M. xenopi was subsequently identified in more than five sputum cultures, using molecular methods. Despite treatment with clarithromycin, rifampicin, ethambutol, and streptomycin, the infiltrative shadow revealed on chest X-ray increased in size. The patient's condition worsened, and a right completion pneumonectomy was performed. The patient consequently died of respiratory failure on postoperative day 47, secondary to the development of a late bronchopleural fistula. This case serves as a reminder to clinicians that the incidence of NTM infection is increasing in Korea and that unusual NTM are capable of causing disease in non-immunocompromised patients.     

胃间质瘤致胃套叠一例

患者女,64岁,因"间断呕吐咖啡样物4 d"入院。患者主诉4 d前无明显诱因出现恶心,呕吐咖啡样物质,共呕吐5次,无晕厥,无意识不清。自服吗丁啉呕吐减轻,仍有腹痛,遂就诊河北省沧州市中心医院。查体:神志清楚,语言流利,腹部平坦,未见胃肠型及蠕动波,触诊腹部柔软,剑突下压痛,无反跳痛及肌紧张,肝脾肋下未触及,肝区及双肾区叩击痛阴性,移动性浊音阴性,肠鸣音正常。既往身体健康,否认高血压病、冠心病、糖尿病史,以及肝炎、结核等传染病史;无手术、外伤、输血史及过敏史。     

In vitro laser Doppler anemometry of pulsatile flow velocity and shear stress measurements downstream from a jellyfish valve in the mitral position of a ventricular assist device

Thrombus formation and hemolysis have both been linked to the dynamic flow characteristics of heart valve prostheses. To enhance our understanding of the flow characteristics past the mitral position of a jellyfish (JF) valve in the left ventricle under physiological pulsatile flow conditions, in vitro laser Doppler anemometry (LDA) measurements were carried out. The hydrodynamic performance of the JF valve was compared with that of a Bjork-Shiley tilting-disk valve (BS mono). The results indicated that both valves created disturbed flow fields and turbulence shear stress levels in the immediate vicinity and up to 1D (diameter of the valvering) downstream from the valve that were capable of causing lethal damage to blood elements. At a location further downstream, the JF valve showed better hydrodynamic performance than the BS in terms of back flow properties and velocity and turbulence stress characteristics. However, any imperfection in the manufacturing of the valve structure, particularly membrane thickness, adversely affected the performance of the JF valve.     

Relationship between exercise-induced heart rate increase and the formation of microbubbles and high-intensity transient signals in mechanical heart valve implanted patients

Introduction

The formation and collapse of vapor-filled bubbles near a mechanical heart valve is called cavitation. Microbubbles can be detected in vivo by doppler ultrasonography (USG) as HITS (high intensity transient signals) in cranial circulation. We investigated the relationship between exercise induced heart rate increase and HITS formation in cranial circulation.

Material and methods

Thirty-nine mechanical heart valve implanted (8 aortic valve replacement (AVR) + mitral valve replacement (MVR), 9 AVR, 22 MVR) patients aged 18-80 years old were included in our study. Microbubbles were counted in the left ventricular cavity via transthoracic echocardiography at rest per cardiac cycle. Afterwards transcranial Doppler USG was performed and HITS were counted in each patient''s middle cerebral artery at 5 min duration. Subsequently an exercise test according to the Bruce protocol was performed. After achieving maximal heart rate, microbubbles in the left ventricle and HITS were counted again.

Results

Microbubbles in the left ventricle and transcranial HITS increased after exercise significantly compared to resting values (15.79 ±10.91 microbubbles/beat vs. 26.51 ±18.00 microbubbles/beat, p < 0.001; 6.13 ±8.07 HITS/5 min vs. 13.15 ±15.87 HITS/5 min, p = 0.001). There was a significant correlation between microbubbles and HITS counts after peak exercise (r = 0.55, p < 0.001).

Conclusions

In our study, we found that the microbubbles were increasing as the heart rate increased and more HITS were propelled to the cerebral circulation. As previously shown, HITS can alter cognitive functions. Therefore heart rate control is essential in mechanical heart valve patients to protect neurocognitive functions.     

Experimental analysis of fluid mechanical energy losses in aortic valve stenosis: Importance of pressure recovery

Current methods for assessing the severity of aortic stenosis depend primarily on measures of maximum systolic pressure drop at the aortic valve orifice and related calculations such as valve area. It is becoming increasingly obvious, however, that the impact of the obstruction on the left ventricle is equally important in assessing its severity and could potentially be influenced by geometric factors of the valve, causing variable degrees of downstream pressure recovery. The goal of this study was to develop a method for measuring fluid mechanical energy losses in aortic stenosis that could then be directly related to the hemodynamic load placed on the left ventricle. A control volume form of conservation of energy was theoretically analyzed and modified for application to aortic valve stenosis measurements.In vitro physiological pulsatile flow experiments were conducted with different types of aortic stenosis models, including a venturi meter, a nozzle, and 21-mm Medtronic-Hall tilting disc and St. Jude bileaflet mechanical valves. The energy loss created by each model was measured for a wide range of experimental conditions, simulating physiological variation. In all cases, there was more energy lost for the nozzle (mean=0.27 J) than for any other model for a given stroke volume. The two prosthetic valves generated approximately the same energy losses (mean=0.18 J), which were not statistically different, whereas the venturi meter had the lowest energy loss for all conditions (mean=0.037 J). Energy loss correlated poorly with orifice pressure drop (r ²=0.34) but correlated well with recovered pressure drop (r ²=0.94). However, when the valves were considered separately, orifice and recovered pressure drop were both strongly correlated with energy loss (r ²=0.99, 0.96). The results show that recovered pressure drop, not orfice pressure drop, is directly related to the energy loss that determines pump work and therefore is a more accurate measure of the hemodynamic significance of aortic stenosis.     

Fatal rhino-orbito-cerebral infection caused by Saksenaea vasiformis in an immunocompetent individual: first case report from India

A 56-year-old female patient presented with history of nasal blockage, nasal bleeding, headache, since one month. On admission the patient developed severe headache, decreased vision of eyes and blindness. Clinical diagnosis of rhino-orbital involvement was confirmed by computerized tomography of the paranasal sinuses. The diagnosis of fungal infection was confirmed by KOH examination, haematoxylin and eosin examination and Gomori's methanamine silver stain of the biopsy material. Diagnosis was confirmed by culture on Sabouraud Dextrose agar, slide culture on Czapek Dox medium and the isolate was identified as Saksenaea vasiformis. The patient was started on intravenous amphotericin B (received only one dose before succumbing), but she did not respond to the treatment, developed hemiparesis, slurred speech, diminished reflexes and ultimately died. The involvement of the brain was confirmed by computerised tomographic scan. We believe this case to be the first case of rhino-orbito-cerebral infection due to Saksenaea vasiformis and that of second case in an immunocompetent patient in the world.