Valvular Failure Research Articles

Modern ideas about the mechanisms of development of valvular insufficiency in chronic venous insufficiency

Annotation. Despite the improvement of methods of diagnosis and treatment of chronic venous insufficiency of the lower extremities, this problem remains relevant and not fully resolved. The confirmation is a large percentage of patients with trophic changes, as a result of deep disorganization of the venous wall and valves in the system of deep and superficial veins. The purpose of this article is to conduct a literature analysis of the various mechanisms of the development of valvular insufficiency in order to improve the treatment of patients with chronic venous insufficiency. A scientific search was carried out for the period from 2000 to 2022 according to the primary search strategy “valvular failure of the veins of the lower extremities”, and the AND/OR combination in the scientific databases MEDLINE (PubMed), Scopus, Web of Science. Among practicing doctors, there are two views on the initial levels of the formation of valvular insufficiency in varicose disease: the beginning of varicose transformation is associated with the expansion of individual venous branches, and the failure of the main trunks of the subcutaneous veins joins much later. Another factor in the pathogenesis of trophic changes in chronic venous diseases is changes in the viscoelastic properties of the walls of deep veins, which lead to valvular insufficiency and impaired venous outflow. The main cause of trophic ulcers in patients with chronic venous insufficiency is the formation of persistent pathological vertical reflux in the system of deep and superficial veins and the presence of horizontal reflux at the level of communicating and penetrating veins of the lower third of the thigh. Orthostatic venous stasis causes a progressive violation of venous hemodynamics and leads to deterioration of microcirculation and disruption of tissue nutrition.

P94 LATE–ONSET POST–INFECTIVE AORTIC PSEUDO–ANEURYSM AFTER BIOPROSTETHIC AORTIC VALVE REPLACEMENT

Abstract A 74 year–old man was admitted three months after SAVR symptomatic for dyspnea. Past medical history: DM type 2, PAD and recent SAVR after diagnosis of severe aortic stenosis, complicated by Stafilococcus Epidermidis blood culture sternal wound dehiscence, requiring Robicsek technique treatment and long–term parenteral antibiotics. He was finally discharged to our cardiac rehab unit. Blood analysis: negative blood culture at admission with negative CPR. Late positivity (after 2 weeks) for a Staphylococcus epidermidis reinfection. EKG: normal atrio–ventricular and intra–ventricular conduction with regular repolarization. TTE: Normal left ventricular volume and ejection fraction with severe aortic regurgitation secondary to suspected partial bioprosthesis detachment. TOE: valvular detachment with a newly–formed pouch located in the mitro–aortic membrane. Bioprosthetic valvular failure (BVF) is a pathological entity arising from a variety of conditions affecting prosthetic heart valves. We present the case of a late–onset partial valvular bioprosthesis detachment associated with a newly–formed pseudoaneurysm due to late infective endocarditis occurred after cardiac surgery, initially manifested with negative cultural findings and suddenly evolved in severe aortic regurgitation. Valvular detachment is an infrequent complication of infective endocarditis. Surgery is the only option capable of restoring a proper anatomy and a correct function of the valvular apparatus. Patient underwent re–do surgery and a new SAVR was needed after confirmation of diagnosis with no residual aortic regurgitation after discharged. BVF is a fearsome and severe condition presenting with a wide spectrum of clinical presentation. Our experience highlights the need of a prompt diagnosis. Late positivity of blood cultures for Stafilococcus Epidermidis probably depend on prolonged antimicrobial therapy after sternal dehiscence treatment which have probably masked laboratoristic finding in early phase (negative CPR and blood cultures). An early intervention is mandatory in order to prevent systemic dissemination or acute decompensation secondary to severe aortic regurgitation. Surgical approach in this case guaranteed a radical treatment with no residual regurgitation or sub–acute microbial infection. 4–weeks parenteral antibiotics during cardiac–rehab efficacy–controlled relapse of CPR and blood–culture (negative before final discharge).

Development of Antithrombogenic ECM-Based Nanocomposite Heart Valve Leaflets.

Thrombogenicity, which is commonly encountered in artificial heart valves after replacement surgeries, causes valvular failure. Even life-long anticoagulant drug use may not be sufficient to prevent thrombogenicity. In this study, it was aimed to develop a heart valve construct with antithrombogenic properties and suitable mechanical strength by combining multiwalled carbon nanotubes within a decellularized bovine pericardium. In this context, the decellularization process was performed by using the combination of freeze–thawing and sodium dodecyl sulfate (SDS). Evaluation of decellularization efficiency was determined by histology (Hematoxylin and Eosin, DAPI and Masson’s Trichrome) and biochemical (DNA, sGAG and collagen) analyses. After the decellularization process of the bovine pericardium, composite pericardial tissues were prepared by incorporating −COOH-modified multiwalled carbon nanotubes (MWCNTs). Characterization of MWCNT incorporation was performed by ATR-FTIR, TGA, and mechanical analysis, while SEM and AFM were used for morphological evaluations. Thrombogenicity assessments were studied by platelet adhesion test, Calcein-AM staining, kinetic blood clotting, hemolysis, and cytotoxicity analyses. As a result of this study, the composite pericardial material revealed improved mechanical and thermal stability and hemocompatibility in comparison to decellularized pericardium, without toxicity. Approximately 100% success is achieved in preventing platelet adhesion. In addition, kinetic blood-coagulation analysis demonstrated a low rate and slow coagulation kinetics, while the hemolysis index was below the permissible limit for biomaterials.

Evaluation of cardiac beat synchronization control for a rotary blood pump on valvular regurgitation with a mathematical model.

We have studied the cardiac beat synchronization (CBS) control for a rotary blood pump (RBP) and revealed that it can promote pulsatility and reduce cardiac load. Besides, patients with LVAD support sometimes suffer from aortic and mitral regurgitation (AR and MR). A control method for the RBP should be validated in wider range of conditions to clarify its benefits and pitfalls prior to clinical application. In this study, we evaluated pulsatility and cardiac load reduction obtained with the CBS control on valvular failure conditions with a mathematical model. Diastolic assist could reduce cardiac load on the left ventricle by decreasing external work of the ventricle even in MR cases while it was not so effective in AR cases. Systolic assist can still promote pulsatility in AR and MR cases; however, aortic valve function should be carefully confirmed since pulse pressure can be wider not due to systolic assist but to AR.

3-year outcomes of self-expanding Corevalve prosthesis - The Italian Registry.

3-year outcomes of self-expanding Corevalve prosthesis - The Italian Registry.

Supplemental Studies for Cardiovascular Risk Assessment in Safety Pharmacology: A Critical Overview

Safety Pharmacology studies for the cardiovascular risk assessment, as described in the ICH S7A and S7B guidelines, appear as being far from sufficient. The fact that almost all medicines withdrawn from the market because of life-threatening tachyarrhythmias (torsades-de-pointes) were shown as hERG blockers and QT interval delayers led the authorities to focus mainly on these markers. However, other surrogate biomarkers, e.g., TRIaD (triangulation, reverse-use-dependence, instability and dispersion of ventricular repolarization), have been identified to more accurately estimate the drug-related torsadogenic risk. In addition, more attention should be paid to other arrhythmias, not related to long QT and nevertheless severe and/or not self-extinguishing, e.g., atrial or ventricular fibrillation, resulting from altered electrical conduction or heterogeneous shortening of cardiac repolarization. Moreover, despite numerous clinical cases of drug-induced pulmonary hypertension, orthostatic hypotension, or heart valvular failure, few safety investigations are still conducted on drug interaction with cardiac and regional hemodynamics other than changes in aortic blood pressure evaluated in conscious large animals during the core battery mandatory studies. This critical review aims at discussing the usefulness, relevance, advantages, and limitations of some preclinical in vivo, in vitro, and in silico models, with high predictive values and currently used in supplemental safety studies.

Clinical Summaries

Clinical Summaries

A 32‐year‐old nursing student with hoarseness and dysphagia to solids

A 32‐year‐old nursing student with hoarseness and dysphagia to solids

Long-term evaluation of Carpentier-Edwards porcine bioprosthesis for rheumatic heart disease

Objectives The clinical results of Carpentier-Edwards standard bioprosthesis have been extensively studied for valvular heart surgery in America and Europe. However, the data of long-term performance of Carpentier-Edwards standard porcine valve in areas with a high prevalence of rheumatic heart disease are still lacking. In this study, we assessed the clinical performance of Carpentier-Edwards standard porcine bioprostheses in a patient group with high prevalence of rheumatic heart disease. Methods A total of 872 patients underwent valvular heart surgery with Carpentier-Edwards standard porcine bioprostheses replacement between 1975 and 1999 and the results were analyzed. Rheumatic etiology counts for 95% of the patients. Mean age of operation was 40 ± 14 years (mitral valve), 43 ± 19 years (aortic valve), and 45 ± 13 years (double valve). Follow-up was 95.6% complete and continued up to 24 years (total 7017 patient-years) with mean of 8.9 ± 5.1 years. Results The operative mortality rate was 5.85%. Actuarial patient survival rates after discharge at 5, 10, 15, and 20 years were 92.5%, 83.8%, 72.3%, and 35.8%, respectively. A total of 442 cases received reoperation due to failure of bioprostheses. The mean duration to valve failure is 12.2 ± 0.4 years. Actuarial estimate of freedom from structural valvular failure at 5, 10, 15, and 20 years were 96.3%, 63.7%, 24.4%, and 7.7%, respectively. Conclusion The long-term result of Carpentier-Edwards standard bioprostheses in the present patient group is satisfactory. However, freedom from valve failure is lower than that of Western series. Younger age at operation and higher prevalence of rheumatic etiology in this area are possible causes.

APPLICATION OF VIBRO-ACOUSTOGRAPHY IN DETECTION OF SINGLE LEG SEPARATION (SLS) IN THE BJORK-SHILEY CONVEXO-CONCAVE (BSCC) HEART VALVES

Background: Occurrence of SLS in the BSCC mechanical heart valves may cause the fracture of outlet strut and total valvular failure. If SLS is detected, it is possible to prophylactically replace the valve. This study has aimed at differentiating the acoustic characteristics of BSCC valves with SLS from those of intact valves. An innovative method of Vibro-Acoustic Spectrography (VAS) has been utilized in this study. Methods: VAS utilizes the radiation force of ultrasound to actively vibrate the object at a range of kHz frequencies, and records the resulting vibrations with a sensitive detector. The recorded data are then used to determine the mechanical frequency response of the object by the Fourier transform. The stress field produced by this technique is highly localized, allowing one to target only the strut and thus avoid interference from vibrations of other structures. Twenty-four BSCC valves were selected: 12 intact valves (25, 27, 29 mm) and 12 explanted valves with SLS (27, 29, 31, 33 mm). The center frequency of the VAS system was 3.0 MHz with the radiation force frequency of 1–15 kHz. Results: It has been demonstrated that the two ends of the fractured leg created three basic configurations: completely separated, partially separated, and completely attached. Also, explanted BSCC valves with SLS consistently exhibited different resonance frequencies than those of the intact valves. Intact valves outlet struts showed resonance frequencies of 6.8–10.8 kHz (size dependent). The corresponding frequencies for the SLS valves ranged from 2.1 kHz to 4.8 kHz, depending on the fracture types. This study has shown that threshold frequency values of 4.8–6.8 kHz can be effectively used to differentiate SLS from intact valves. Conclusions: VAS can be effectively used as an active probing method for remote detection of SLS in the BSCC heart valves.

Infective Endocarditis Due to Unusual or Fastidious Microorganisms

Infective endocarditis due to fastidious microorganisms is commonly encountered in clinical practice. Some organisms such as fungi account for up to 15% of cases of prosthetic valve infective endocarditis, whereas organisms of the HACEK group (Haemophilus parainfluenzae, H. aphrophilus, and H. paraphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae) cause 3% of community-acquired cases of infective endocarditis. Special techniques are necessary to identify these microorganisms. A history of contact with mammals or birds may suggest infection caused by Coxiella burnetii (Q fever), Brucella species, or Chlamydia psittaci. A nosocomial cluster of postsurgical infective endocarditis may be caused by Legionella species or Mycobacterium species. If risk factors that are commonly associated with fungal infections (cardiac surgical treatment, prolonged hospitalization, indwelling central venous catheters, and long-term antibiotic use) are present, fungal endocarditis is possible. Patients with endocarditis and a history of periodontal disease or dental work in whom routine blood cultures are negative might have infection due to nutritionally variant streptococci or bacteria of the HACEK group. Communication between the microbiologist and the clinician is of crucial importance for identification of these microorganisms early during the course of the infection before complications such as embolization or valvular failure occur. In this article, we review the microbiologic and clinical features of these organisms and provide recommendations for diagnosis and treatment.

Popliteal Valvular Construction Using a Silastic Sling (Technique II) for Deep Venous Insufficiency of the Lower Limb

Objective: To establish the safety and efficacy of a silastic sling procedure for reconstructing popliteal vein. Design: Prospective survey of patients undergoing surgical treatment for popliteal vein reflux. Setting: Department of Surgery, County Hospital, Bad Karlshafen, Germany. Patients: 209 patients undergoing surgery for popliteal vein incompetence. Interventions: Silastic sling procedure (Technique II) for correction of popliteal vein incompetence. Main outcome measures: Continuous wave Doppler ultrasound examination of popliteal vein, ambulatory foot vein pressure measurements, lower limb venography. Results: One week following surgery 202 patients (of 209) reported relief of pain and reduction of limb oedema. 77 patients with ulcers (of 85) healed following the surgical procedure. Ambulatory venous pressure improved from 71 SD 11 mmHg to 36 SD 17 mmHg. There was prolongation of the venous refilling time from 9 SD 5 seconds to 27 SD 17 seconds. Postoperative phlebography in 92 patients was performed on the tenth post-operative day and in no patient was deep vein thrombosis observed. In 82 of these patients phlebography demonstrated that the constructed popliteal valve was patent. Conclusions: Construction of a popliteal valve using the author's silastic sling technique is a satisfactory method for managing patients with otherwise uncontrolled popliteal vein reflux due to either primary valvular failure or previous deep vein thrombosis.

Augmentation Cystoplasty and Closure of the Urethra for the Destroyed Lower Urinary Tract

Five paraplegic patients with pressure ulceration complicated by incontinence related to fistula formation were treated by deliberate closure of the urethra and augmentation cystoplasty with a continent stoma. This procedure is similar in scope to urinary diversion but preserves a low-pressure reservoir and obviates the use of tubes for drainage of urine. Overall outcome was excellent. Valvular failure occurred in one patient and required revision. The follow-ups range from 1 to 5 years, with a mean of 24 months. One patient developed reservoir calculi as a late complication, necessitating removal with flexible endoscopy via the continent conduit. All patients have preserved normal upper tracts. Augmentation cystoplasty with closure of the urethra is a reasonable procedure in such patients providing for low-pressure urinary storage and permitting secondary or simultaneous plastic surgical procedures on perineal pressure ulceration and osteomyelitis.

Accurate Patient Diagnosis of Acute Porcine Valve Failure

Spontaneous porcine bioprosthetic valve failure is usually of gradual onset. We report a case of acute porcine mitral valve rupture resulting in rapid hemodynamic decompensation. The patient perceived the moment of valvular failure as the abrupt onset of a vibrating sensation in his chest. As the number of patients with porcine bioprostheses continues to increase, acute valvular failure may become a more common clinical entity.

Bioprosthetic valvular failure: Clinical and pathological observations in an experimental animal model

We compared the clinical, hemodynamic, and morphological findings in 18 young sheep in which porcine valvular bioprosthesis (eight animals) and bovine pericardial bioprostheses (10 animals) were implanted in the tricuspid position. At the time of terminal elective studies (mean of 5.2 +/- 0.2 months after implantation), six animals had ascites, 16 had hepatic congestion, and four had bioprosthetic valvular infection. Hemodynamic studies (n = 10) showed that the tricuspid transvalvular mean diastolic gradients were not different at implantation and at termination of the study (4.7 +/- 0.8 versus 4.9 +/- 0.9 mm Hg); however, tricuspid valve end-diastolic gradients increased from 1.2 +/- 0.6 to 3.9 +/- 0.5 mm Hg (p less than 0.01). Each of the 18 valves had calcific deposits. Quantitative studies revealed that implanted porcine valvular bioprosthesis (n = 7) contained a mean of 323 +/- 165 mg of calcium/gm of dry weight of cuspal tissue, in contrast to 0.2 mg/gm in unimplanted porcine valvular prostheses. Similarly, implanted bovine pericardial bioprostheses (n = 6) contained a mean of 421 +/- 115 mg of calcium/gm of dry weight of cuspal tissue, in contrast to 0.3 mg/gm im unimplanted bovine pericardial bioprostheses. Morphological findings in both types of bioprostheses included calcific deposits, collagen degeneration, leaflet immobilization and retraction, and fibrous sheaths. The latter were more extensive in bovine pericardial bioprostheses than in porcine valvular bioprostheses. We conclude: (1) that the pathological alterations which develop in bovine pericardial bioprostheses are generally similar to those in porcine valvular bioprostheses, but may be more severe; (2) that these alterations lead to physiological and clinical sequelae similar to those of bioprosthetic valvular failure in human subjects; and (3) that young sheep constitute an excellent experimental model for in vivo testing of bioprosthetic cardiac valves.

Pulmonary artery patch homograft. A canine experimental evaluation of a cusp-bearing homograft patch.

The reconstruction of the right ventricular outflow tract with a freeze-dried pulmonary artery patch after resection of a patch containing the ventral semilunar valve is demonstrated as a method to test the viability of the freeze-dried pulmonary artery homograft. In 10 animals, the lyophilized patch was cusp-bearing and in 5 animals – for control purposes – non-cusp-bearing. The observed period ranged from 1 to 12 months. Transvalvular pressures were controled in elected time intervals. Macroscopic and histologic evaluation was carried out after sacrifice. The valve-bearing patches gave no sign of valvular failure in the functional and morphological studies. The control group showed varying degrees of pulmonary valvular insufficiency, but the patches were, as the valve-bearing ones, morphologically acceptable.

The clinical picture of adult rheumatic carditis.

SummaryIn a series of 96 cases of adult rheumatic carditis, symptoms of myocarditis were present in 70 per cent; signs of valvulitis were seen in 23 per cent, and pericarditis was the dominant clinical feature in 7 per cent. A follow-up examination was made on 55 patients, on the average 8 years after the attack of rheumatic fever. A recurrence of carditis was observed in 3 patients only, mitral heart disease with cardiac decompensation had developed in 1 patient, and in 23 patients there were some slight signs of previous carditis. In 14 of the last mentioned cases, or in 25 per cent of the patients followed up, the auscultation finding suggested an organic lesion of the mitral valve, however without other clinical or fluoroscopic changes characteristic of mitral heart disease.A relative mitral valve failure, caused by the inflammatory heart damage, was a common finding, as was indicated by several cases in which murmurs during the convalescence stage, suspicious for valvular failure still later had disa...