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PubMed2004

Comparison of systolic cardiac function before and after treatment of atrial fibrillation in horses with and without additional cardiac valve insufficiencies.

Clinical, electrocardiographic and echocardiographic examinations were conducted before therapy and 4 days after conversion to normal sinus rhythm in 15 horses with a history of atrial fibrillation of 2-6 months duration. Seven horses showed no other signs of cardiac disease. Four horses suffered additionally from mitral valve insufficiency, while six horses had aortic valve insufficiency, including two of the four horses with mitral valve insufficiency, but none had signs of congestive heart failure. Doppler echocardiographic estimates of various variables were made for assessment of systolic heart function. These included heart rate, stroke volume, cardiac output and cardiac output per kg of body weight (heart index). After conversion to normal sinus rhythm, the horses without heart valve insufficiency showed a statistically significantly decreased heart rate (-24%) and cardiac output (-3%), but an increase in stroke volume (+8.4%) and heart index (+9%). The horses with heart valve insufficiency experienced a statistically significant decrease in heart rate (-21%) after conversion to normal sinus rhythm, but showed an increase in all other variables. Cardiac output increased statistically significantly by 20%, stroke volume by 54% and heart index by 58%.

Animals↗
PubMed1976

Cardiac valve replacement in the first 21 years of life.

From 1969 through 1974, 25 patients under age 21 years had prosthetic cardiac vlave replacement at the Emory University Hospital. Twenty-nine valves were replaced in this group. Patients ranged in age from 2 to 21 years, with a mean of 14 years. Concomitant correction of associated cardiac lesions was required in 14 (56%). Five (21%) had had prior open valvuoplastic procedures. Operative mortality for the entire group was 12%, with an additional late mortality of 8%. There have been no early or late deaths in the last three years' experience. Best results are obtained when early correction of isolated valvular lesions is done as soon as clinical deterioration on vigorous medical management is recognized. The presence of multiple intrcardiac lesions or prior valve surgery does not preclude excellent results. Current indications for surgical correction and follow-up management are presented.

Adolescent↗
PubMed2006

Characterization of molecules mediating cell-cell communication in human cardiac valve interstitial cells.

Cell-cell interactions and adhesion determine cellular architectural organization, proliferation, signaling, differentiation, and death. We have identified the molecular components of different cell-cell junctions in human valve interstitial cells (ICs) both in situ and in culture. ICs were isolated, cultured, and phenotyped for cell surface and cytoplasmic markers by flow cytometry and immunocytochemistry. Western blotting was used to identify and quantify the molecular components of these cell-cell junctions in human valve ICs and compared with expression in smooth muscle and fibroblast cell types. N-cadherin and desmoglein were weakly detected on a low percentage of ICs, and the other classical cadherins were not detected. alpha- and beta-catenin, but not gamma-catenin, were expressed at equivalent levels by all valve ICs. Valve ICs did not express connexin-32 and -40; however, connexin-26 and -43 were equally expressed by a low percentage of ICs, demonstrating cell surface and cytoplasmic expression ,and connexin-45 was weakly expressed. The other cell types also expressed N-cadherin, alpha- and beta-catenin, desmoglein and connexin-43. The expression of these junctional molecules was predominantly by valve ICs on the inflow side of the valves. Human valve ICs have the ability to communicate with other valve ICs and mediate cell-cell adhesion via N-cadherin, connexin-26 and -43, and desmoglein. The junctions between valve ICs could support an interconnecting and coordinated cellular unit capable of controlling the functionality of the valve.

Cell Communication↗
PubMed1982

Coenzyme Q10: the prophylactic effect on low cardiac output following cardiac valve replacement.

A randomized, prospective study of the effectiveness of preoperative administration of coenzyme Q10 on the prophylaxis of postoperative low cardiac output state was performed in 50 patients with acquired valvular diseases necessitating valve replacement. There were 25 patients in the treatment group and 25 in the control group. Patients in the treatment group received 30 to 60 mg of coenzyme Q10 orally for six days before operation. Preoperative clinical variables, operative procedures, total cardiopulmonary bypass time, and aortic cross-clamping time were similar for the two groups. Postoperatively, mild to severe low cardiac output state developed in 28 of 50 patients (56%) and necessitated the administration of considerable amounts of inotropic agent. The treatment group showed a significantly lower incidence of low cardiac output state during the recovery period than the control group (p less than 0.05). These results suggest that preoperative administration of coenzyme Q10 will increase the tolerance of human hearts to ischemia during aortic cross-clamping.

Adult↗
PubMed2006

Durability of a cardiac valve leaflet made of calf pericardium: fatigue and energy consumption.

We studied the mechanical behavior of membranes of calf pericardium, similar to those employed in prosthetic valve leaflets, when subjected to tensile fatigue. The objective was to assess its durability, as a fundamental property of cardiac bioprosthesis, and analyze the energy consumption. For this purpose, the authors built a hydraulic simulator to subject a spherical valve leaflet made of calf pericardium to cyclic stress mimicking cardiac function. A total of 522 assays were performed in 40 samples, subjected to cyclic pressures greater than 6 atm, and 482 subjected to pressures ranging between 2 and 6 atm. The mathematical expression that establishes the relationship between the pressure exerted and the frequency was obtained. If we assume that the function is continuous, this equation provides the range of fatigue tolerated for a given number of cycles. Using the optimal values (the five highest values per series), the expression was found to be y = 9.95x(-0 1214) (R(2) = 0.955), where x represents the frequency in cycles per second and y the pressure in atmospheres. In addition, we established the mathematical relationship between the energy consumed and the frequency, which was a function of the pressure exerted, regardless of the region or zone from which the samples had been obtained. The methods of manual and morphology-based selection employed produced widely dispersed results. When a mechanical criterion was included, the similarity in the energy consumed during fatigue testing markedly improved the correlation, with a coefficient of determination between paired samples of R(2) = 0.7477. A mechanical criterion, such as energy consumption, can help to improve sample selection and produce more consistent results. Finally, we obtained the mathematical expression that relates the energy consumed to the pressure exerted and the number of cycles per second to which the valve leaflet was subjected. This procedure enables us to establish the limit to the energy that a biomaterial can consume over a period of time during which it is subjected to a working pressure and, thus, calculate more precisely its durability.

Animals↗
PubMed1989

An improved noninvasive method for measurement of cardiac output and evaluation of left-sided cardiac valve incompetence.

A time-saving method was developed to label red blood cells in vitro with 99mTc while avoiding centrifugation. After tin incubation, extracellular tin was oxidized by sodium hypochlorite, and EDTA was added for stabilizing the complex prior to 99mTc incubation. Labeling yields were 95%, and in vivo decay showed a high stability with a mean biologic half-life of eleven hours. The first-passage radionuclide technique for determination of cardiac output using the above-mentioned tracer was evaluated by using the left ventricle as area-of-interest with individual background correction after complete mixing of the tracer. This technique showed a high level of agreement with invasive methods. By combining this method for measurement of the forward stroke volume with the multigated equilibrium principle for determination of the total left ventricular stroke volume using similar background corrections, an exact evaluation of regurgitation fractions was obtained. In patients with aortic and mitral valve disease the noninvasive radionuclide technique gave similar but probably more accurate results as compared with contrast aortography and ventriculography. The radionuclide technique may be suitable for monitoring and selecting patients for surgical treatment.

Aortic Valve Insufficiency↗
PubMed1999

Thermal analysis characterization of aortic tissues for cardiac valve bioprostheses.

Two multistep extractions were achieved on porcine aortic tissues to obtain acellular matrices used for cardiac bioprostheses. The evaluation of structural modifications and the possible damage of extracellular matrix fibrous proteins were investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Protein-water interactions and degradation temperatures were determined by TGA. DSC was used to characterize protein thermal transitions (glass transition and denaturation), which provided information on the dynamic structure of the aortic tissue components. Sodium dodecyl sulfate (SDS) extraction had a destructuring effect, while Triton and cholate treatments did not affect the structural integrity of either elastin and collagen. A DSC comparison showed that SDS destabilizes the collagen triple helical domain and swells the elastin network.

Absorption↗
PubMed2005

The St. Jude Medical cardiac valve prosthesis: a 25-year experience with single valve replacement.

BACKGROUND: From October 1977 to October 2002, 4,480 patients (age range, 17 to 94 years; average, 64 +/- 13 years) underwent single valve replacement with the St. Jude Medical heart valve. Of 2,982 aortic (AVR) and 1,498 mitral valve replacements (MVR), concomitant coronary artery bypass grafting was performed on 42% and 33%, respectively. METHODS: Cardiac Surgical Associates has maintained an independent database of patients having valve replacement with the St. Jude Medical prosthesis since the world's first implant. Patients were contacted by questionnaire or phone from November 2002 through June 2003. Hospital course and valve-related events were verified by patient chart review or physician contact. RESULTS: Follow-up was 95% complete. Operative mortality was 4% with AVR and 9% with MVR. Total follow-up was 32,190 patient-years (range, 1 month to 24.8 years; average, 7 +/- 5 years). During the study period, patient freedom from late mortality was 61% (AVR, 61%; MVR, 63%), and from valve-related mortality 92% (AVR, 93%; MVR, 91%). Freedom from thromboembolic events was 85% (86% AVR, 81% MVR), from bleeding events, 81% (81% AVR, 81% MVR), from reoperation, 98% (99% AVR, 97% MVR), from endocarditis, 98% (99% AVR, 98% MVR), and from valve thrombosis, 99% (99% AVR, 98% MVR). There was one MVR structural failure (0.06%). CONCLUSIONS: The St. Jude Medical valve has proven to be an effective and durable valve prosthesis with a low event rate during the long term.

Adolescent↗
PubMed2000

Cardiac valve papillary fibroelastomas: clinical, histological and immunohistochemical studies and a physiopathogenic hypothesis.

BACKGROUND AND AIM OF THE STUDY: Cardiac papillary fibroelastoma (CPF) is a rare and histologically benign tumor, but may have a malignant propensity for life-threatening complications; thus, surgical removal is justified. Case histories were reviewed of four patients who underwent surgical management after diagnosis of CPF located on aortic (n = 2) or mitral (n = 2) valves. Our aim was to provide explanations for the clinical diversity of the lesions and, using histological and immunohistochemical methods, to hypothesize the genesis of these tumors. METHODS: Among four patients with a diagnosis of valvular CPF, two had previous and recent history of neurological embolic symptoms with small echographically located tumors attached to the ventricular side of aortic cusps. Two other patients (one with paroxysmal atrial fibrillation, one with no neurological or rhythmically related stroke) had CPFs located on the posterior or anterior mitral leaflets. RESULTS: Surgical excision was performed with a conservative valve-sparing approach. Histological and specific immunohistochemical (IHC) studies were conducted on all samples. The postoperative course was uneventful, and histological analysis confirmed the diagnosis of CPF with typical fronds characterized by three successive layers. In the first two patients there was correlation between neurological events and the presence of thrombus aggregated on the injured superficial endothelial layer. In the other patients, no endothelial damage or thrombus was found. IHC studies showed dysfunction of the superficial endothelium, a centrifugal mesenchymal cellular migration arising from the central layer to the superficial layer with differentiation steps, the presence of dendritic cells in the intermediate layer, and remnants of cytomegalovirus (CMV) in the intermediate layer. CONCLUSION: Despite their benign histological aspect, and independent of their size, CPFs justify surgical excision because of their high potential to systemic embolization. In most cases, valve sparing management is possible with no observed recurrence after complete excision. The presence of dendritic cells and CMV strongly suggests the possibility of a virus-induced tumor, therefore evoking the concept of a chronic form of viral endocarditis.

Adult↗