Cavitation versus Degassing: In Vitro Study of the Microbubble Phenomenon Observed During Echocardiography in Patients with Mechanical Prosthetic Cardiac Valves

Background: With the advent of second harmonic imaging in echocardiography, microbubbles have been observed during opening and closure of mechanical prosthetic valves. The single phenomenon of cavitation, an extremely short event described in the literature, cannot explain the persistence of microbubbles during several hundred milliseconds. Therefore, in vitro we reproduced two distinct phenomena created by a local depression occurring during the closure and/or opening of prosthetic valves: Cavitation and degassing. Methods: We used a water circuit system enriched with CO₂ that passes through a Venturi tube in order to create variable pressure gradients. Three types of observations were performed: (1) the dimensions of the bubbles as a function of pressure, (2) calibration of the echocardiograph, and (3) comparison and illustrations of the difference between bubble formation by cavitation (vaporization) and degassing (liberation of CO₂). Results: According to the different pressures exerted, the dimensions of the bubbles only vary by several microns, not measurable in practice. Second, the calibration of the echocardiograph reveals that the dimensions of the bubbles measured by ultrasound are greater by a factor of 1.75. Finally, the observed cavitation is a short phenomenon (several milliseconds) and happens under a great local pressure gradient. The degassing produces microbubbles lasting up to as long as > 1 second under much lower pressure. Conclusion: This in vitro study suggests that microbubbles observed during several hundred milliseconds after the opening of prosthetic cardiac valves are the result of degassing of CO₂ in blood rather than a cavitation phenomenon as suggested in the literature.     

Ten Years of Infective Endocarditis: A Clinicopathologic Study

ABSTRACT The records of 46 patients with infective endocarditis diagnosed either clinically or postmortem were analyzed. Twenty-six patients were over 60 years of age. S. aureus was the predominant organism, almost exclusively found in patients with acute endocarditis. Thirty-six patients had pre-existing heart disease, the most common being non-rheumatic valvular calcification and congenital defects. Two thirds of the patients, especially those with aortic valve regurgitation, developed new or progressive heart failure. A correct clinical diagnosis was established in only 30 patients. Twenty-three patients died, the mortality being 71% in acute and 32% in subacute disease. Only one of eight patients with prosthetic valve infection died. Four patients required urgent valve replacement. Early surgical intervention should be considered in patients with uncontrolled heart failure.     

Acquired AortoVentricular Tunnel: A Rare Complication of Infective Endocarditis

A 26-year-old man presented to emergency department with fever associated with night sweating and weight loss since 2 months prior to admission. He was an intravenous heroin user admitted for infective endocarditis of aortic valve 1 year ago. Transthoracic echocardiography followed by the transesophageal study showed bileaflet aortic prosthesis with normal transvalvular gradient and severe paravalvular aortic insufficiency. A pseudoaneurysm of intervalvular fibrosa connecting left ventricular outflow tract (LVOT) to noncoronary sinus of valsalva was detected.     

Neocuspidization of the Pulmonary Valve with Autologous Pericardium in the Adult Patient with Ventricular Septal Defect and Infective Endocarditis: A Case Report and Review of the Literature

Congenital heart disease (CHD) is one of the risk factors for developing infective endocarditis (IE). Right-sided IE occurs in 5%–10% of endocarditis cases, and pulmonary valve (PV) is involved in less than 2% of such patients. Literature data are few, and optimal treatment methods, indications for surgery, and types of operative techniques are still under debate. We present an adult patient with a rare combination of the ventricular septal defect (VSD) and PV IE who underwent surgical treatment. Neocuspidization with autologous pericardium was utilized for the reconstruction of his PV. We discuss details of this novel surgical technique.     

The Changing ‘Face’ of Endocarditis in Kentucky: An Increase in Tricuspid Cases

Background

Advancements in medical technology and increased life expectancy have been described as contributing to the evolution of endocarditis. We sought to determine whether there has been a change in the incidence, demographics, microbiology, complications, and outcomes of infective endocarditis over a 10-year time span.

Methods

We screened 28,420 transthoracic and transesophageal echocardiogram reports performed at the Gill Heart Institute for the following indications: fever, masses, emboli (including stroke), sepsis, bacteremia, and endocarditis in 2 time periods: 1999 to 2000 and 2009 to 2010. Data were collected from diagnosed endocarditis cases.

Results

Overall, 143 cases of infective endocarditis were analyzed (48 in 1999-2000 and 95 in 2009-2010). The endocarditis incidence per number of admissions remained nearly constant at 0.113% for 1999-2000 and 0.148% for 2009-2010 (P = .153). However, tricuspid valve involvement increased markedly from 6% to 36% (P < .001). Also, reported history of intravenous drug use increased from 15% to 40% (P = .002). Valvular complications doubled from 17% to 35% (P = .031). Septic pulmonary emboli increased from 10% to 25% (P = .047). Despite these noted differences, inpatient mortality remained unchanged at 25% and 28% (P = .696) for the 2 time periods, respectively.

Conclusions

The incidence of endocarditis at the University of Kentucky Medical Center has not changed and mortality remains high, but the “face of endocarditis” in Kentucky has evolved with an increased incidence of tricuspid valve involvement, valvular complications, and embolic events.     

A Fracture Mechanics Model for Cavitation Damage in Mechanical Heart Valve Prostheses

In the 1994 Replacement Heart Valve Guidance of the Food and Drug Administration (FDA), both cavitation and damage tolerance analyses are required for mechanical heart valves (MHV). Cavitation results from a sequence of events. First, vaporous bubbles are generated in the blood flow. They then collapse to form high-speed micro liquid jets, striking against the solid valve boundary, and subsequently causing pits on the surface. Micro cracks may initiate around the pitted areas under repeated jet impacts superimposed with cyclic loading. These events are, of course, closely related to the shape and size of an MHV. The factors specified in the current FDA guidance and considered by many authors for calculating working stresses, including static stresses, dynamic stresses, residual stresses, and stress concentrations, appear to be inadequate. The local high pressure caused by cavitation jets is another important factor which may aggravate crack propagation. The present paper is aimed at quantitatively assessing the influence of cavitation jets on the safe service life of an MHV using a damage tolerance approach. A new fracture mechanics model for estimating service lives of MHV prostheses is proposed, in which bubble dynamics and cavitation phenomenon are incorported. Numerical results show that the local high pressure is dominant, and is large enough to cause a crack to propagate at a greater rate, and resulting in much shorter fatigue life for an MHV.     

Tropheryma whipplei Endocarditis: A Two-patient Case Series

Background

Whipple endocarditis is caused by Tropheryma whipplei and is a well-described complication of Whipple's disease. Limited and small case series have been published regarding the presentation, diagnosis, and clinical course of this disease.

Methods/Results

We describe 2 cases of patients with T. whipplei endocarditis, one of which underwent a successful heart transplant.

Conclusion

In both cases of Whipple's endocarditis, there was a subacute prodromal phase followed by an acute rapid decompensation with severe destruction of the aortic valve, heart failure, and embolism. Because the diagnosis of T. whipplei endocarditis is typically not made until pathological examination of tissue, clinicians must have a high suspicion for it in the absence of other offending organisms, especially among middle-aged white males with sub-acute symptoms and embolic complications.     

A Case of Brucellosis Complicated by Endocarditis and Disseminated Intravascular Coagulation

ABSTRACT Brucellosis, being eradicated among domestic animals in some countries, is still prevalent in some others where it poses a potential threat to the consumers of milk and cheese and those working with animals and meat. The patient presented below had contracted a severe and long-standing Brucella abortus infection by ingesting raw camel milk. She had signs of endocarditis and disseminated intravascular coagulation, but recovered when treated with tetracyclin and streptomycin.     

Tumor Plop in a Febrile Child: Unusual Presentation of Tricuspid Valve Endocarditis

Tricuspid valve endocarditis in a structurally normal heart of child is extremely rare and mysterious disease, which may mimic several other illnesses. We are reporting here a six-year-old child who presented with prolonged fever and unusual auscultatory sound of tumor plop, later proven to having tricuspid valve endocarditis by 2D echocardiography. The patient underwent surgical excision of the vegetations with repair of the tricuspid valve leaflets with successful outcome.     

Left Atrial Wall Dissection: A Rare Sequela of Native-Valve Endocarditis

Left atrial wall dissection is a rare condition; most cases are iatrogenic after mitral valve surgery. A few have been reported as sequelae of blunt chest trauma, acute myocardial infarction, and invasive cardiac procedures. On occasion, infective endocarditis causes left atrial wall dissection.We report a highly unusual case in which a 41-year-old man presented with native mitral valve infective endocarditis that had caused left atrial free-wall dissection. Although our patient died within an hour of presentation, we obtained what we consider to be a definitive diagnosis of a rare sequela, documented by transthoracic and transesophageal echocardiography.     

Infective Endocarditis Complicated with Anterior Mitral Leaflet Abscess: A Case Report

Infective endocarditis (IE) is defined as infection of endocardial surface of the heart. It may include one or more heart valves, the mural endocardium or a septal defect. Its intracardiac effect includes severe valvular insufficiency which may lead to intractable congestive heart failure and myocardial abscess. Infective endocarditis especially complicated by an abscess is associated with high mortality, despite the medical and surgical therapeutic options available. Surgical intervention is indicated in cases of heart failure or uncontrolled infection and sometimes for the prevention of embolic phenomena. We report a case of 42 yrs/M with RVHD admitted in Dr D.Y.Patil hospital, Kolhapur. He had high grade, continuous fever, vomiting, cough with expectoration since 15 days prior to admission. He had prior embolic stroke 2 months back from which he recovered completely. The diagnosis of Infective endocarditis was confirmed clinically & echocardiographically by Duke''s criteria. His ECHO showed severe MR, Moderate MS and large vegetations on AML oscillating through mitral orifice along with subvalval (mitral) abscess. Due to severe haematemesis following Mallory weiss tear surgical intervention was not possible. Patient succumbed as a result of refractory pulmonary oedema.     

Retrograde Transcatheter Closure of Mitral Paravalvular Leak through a Mechanical Aortic Valve Prosthesis: 2 Successful Cases

The presence of a mechanical aortic valve prosthesis has been considered a contraindication to retrograde percutaneous closure of mitral paravalvular leaks, because passing a catheter through the mechanical aortic valve can affect the function of a mechanical valve and thereby lead to severe hemodynamic deterioration. We report what we believe are the first 2 cases of retrograde transcatheter closure of mitral paravalvular leaks through a mechanical aortic valve prosthesis without transseptal or transapical puncture. Our experience shows that retrograde transcatheter closure of mitral paravalvular leaks in this manner can be an optional approach for transcatheter closure of such leaks, especially when a transapical or transseptal puncture approach is not feasible. This technique might also be applied to other transcatheter procedures in which there is a need to pass a catheter through a mechanical aortic valve prosthesis.     

Echocardiographic mimicker of thrombus on a mechanical aortic valve prosthesis due to cavitation: A paradoxical phenomenon of pressure recovery

We describe a case of a mass‐like echocardiographic density on a mechanical prosthetic aortic valve. We initially suspected a thrombus vs vegetation on transthoracic echocardiography, but after transesophageal echocardiography, the density was subsequently determined to be cavitation by reviewing the initial images in slow motion.     

Fusobacterium necrophorum Endocarditis with Liver Abscesses: A Case Report and Review of the Literature

Fusobacterium necrophorum is a very rare cause of endocarditis. We herein report a case of F. necrophorum endocarditis with liver abscesses in a 51-year-old woman. This is the first reported case of monomicrobial F. necrophorum endocarditis to present in a patient over 50 years old. We also reviewed 10 reported cases, including the present case. Our review indicated that anaerobic bacteria, including Gram-negative anaerobic bacilli such as F. necrophorum, should be considered in the differential diagnosis of infective endocarditis, especially in patients without preexisting organic heart disease.