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PubMed1999

Regression of ventricular repolarisation inhomogeneity after aortic bileaflet valve replacement in patients with aortic stenosis.

BACKGROUND: Aortic valve replacement relieves mechanical outflow obstruction in patients with aortic stenosis. However, there is limited information on whether aortic valve replacement can provide regression of ventricular repolarisation inhomogeneity. OBJECTIVES: To determine whether aortic valve replacement can provide regression of ventricular repolarisation inhomogeneity in patients with aortic stenosis after bileaflet aortic valve replacement. METHODS: We studied the changes of electrocardiographic QT or QTc intervals and QT or QTc dispersions of 71 patients with severe aortic stenosis and angiographically insignificant coronary lesions (<50% in diameter) before and after valve replacement (6+/-3 days after operation). Seventy-one healthy control subjects, matched for age and sex, served as control subjects. Twelve-lead electrocardiograms and echocardiographic examinations were measured before and after surgery. The QT interval was corrected for heart rate using the standard Bazett formula. QT dispersion was defined as the difference between maximal and minimal QT interval measurements occurring among any of the 12 leads on a standard electrocardiogram. QTc dispersion was calculated in a manner similar to QT dispersion. No subject had fewer than nine measurable leads. RESULTS: Left ventricular systolic blood pressure, pressure gradient across aortic valve, left ventricular mass index, and systolic wall stress were significantly reduced after valve replacement compared with before valve replacement. The QT interval significantly decreased from 425+/-38 ms to 398+/-32 ms after replacement (P<0.0001). The QTc dispersion significantly decreased from 62+/-25 ms to 32+/-13 ms after replacement (P<0.0001). The value of QT or QTc dispersion after replacement was similar to that in controls. Univariate analysis revealed that QTc dispersion was significantly only correlated with left ventricular mass index (r=0.236, P=0.05). Multivariate analysis revealed that the best predictor of QTc dispersion was sex and left ventricular mass index (P=0.008 and 0.005, respectively). CONCLUSIONS: Our study demonstrated a favorable consequence of aortic valve replacement distinct from hemodynamic improvement. Patients with aortic stenosis before valve replacement have abnormal prolonged QT or QTc intervals and increased QT or QTc dispersions. After successful valve replacement left ventricular mass index regressed and QT or QTc intervals and QT or QTc dispersions were normalized. These findings warrant further investigation in a large trial and long-term follow-up for clinical implications.

Aortic Valve↗
PubMed2003

Gerbode's defect resulting from infective endocarditis.

We present a report of a Gerbode's defect (left ventricular-right atrial communication) resulting from bacterial endocarditis in a 63-year-old man. Also presented is a brief overview of the literature and a possible preoperative echocardiographic diagnostic criterion relating to this unusual condition.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Replacement of the left-side valves of an implanted total artificial heart.

The MagScrew total artificial heart (TAH) is under development. Despite its anticipated durability and reliability, the possibility of a bioprosthetic valve malfunction exists. As a result, the potential for valve replacement surgery, instead of device replacement, would be desirable after a TAH implant. In two of our 90-day animal experiments, we successfully replaced the left-side valves through a left thoracotomy opposite to the right-sided incision site for the initial TAH implant. The results of these cases suggest that the left-side valves could also be replaced through a left thoracotomy approach in humans. To confirm the ability to access the left-side valves in humans, four human cadaver studies were performed with the use of a mock pump designed for human application. This report describes the operative techniques for left-side valve replacement in animals and discusses the advantages of a left thoracotomy in clinical situations, based on results from the human cadaver studies.

Animals↗
PubMedDate not supplied

Clinical and hemodynamic comparison of the Medtronic Freestyle and Toronto SPV stentless valves.

The excellent hemodynamics of stentless valves have been observed by numerous investigators. With the recent release of the Toronto SPV (stentless porcine valve) and the Medtronic Freestyle stentless valves in North America, it is appropriate to now compare the clinical and hemodynamic performance of these devices. We analyzed the results of 995 patients who underwent aortic valve replacement (AVR) with either of the two valves; in all cases a subcoronary implant technique was used. There were important differences in the preoperative characteristics for the two groups: Medtronic Freestyle patients were notably older than the Toronto SPV patients (70.7+/-8.6 vs 61.8+/-11.1 years, p < 0.001) and were markedly more symptomatic (p < 0.0001). In the Toronto SPV group, most patients had New York Heart Association (NYHA) Class II (41.5%) or Class III (44.7%) symptoms preoperatively, while in the Freestyle group, 61.5% were in Class III and 12.5% were in Class IV. There were no notable differences in mortality or morbidity for the two groups. Both devices demonstrated a meaningful decrease in mean gradient and a corresponding increase in effective orifice area (EOA). Furthermore, the indexed EOA (EOA/body surface area [BSA]) was > 1cm2/m2 for all valves indicating there was no patient-prosthetic mismatch. There was a meaningful decrease in left ventricular (LV) mass as well as LV mass index (LVMI) for both devices up to 3 years postoperatively. Our data indicate that there were no differences in clinical outcome or hemodynamic performance of these two valves. Both devices offer excellent results with normalization of LV function.

Aged↗
PubMed2005

Stentless vs. stented aortic valve replacement: left ventricular mass regression.

The aim of this retrospective study was to evaluate the time-related regression of left ventricular hypertrophy after stentless vs. stented aortic valve replacement. From January 1992 to December 2002, 145 patients had a Toronto stentless porcine valve and 106 had a stented Carpentier-Edwards aortic valve replacement. Over a 10-year follow-up, survival was superior in the Toronto group vs. the Carpentier-Edwards group (84% vs. 74% at 4 years; 78% vs. 68% at 6 years; p < 0.001). A significant and constant reduction of peak and mean transvalvular gradients after valve replacement resulted in substantial regression of left ventricular mass index in both groups, which did not reach statistical significance. However, this phenomenon stopped at 3 years, and left ventricular mass index increased slowly after 5 years. Stentless and stented bioprostheses both showed good early and late clinical and hemodynamic outcomes, with the advantage of better midterm survival for stentless xenografts.

Adult↗
PubMed2006

In search of a pediatric cardiac surgeon's 'Holy Grail': the ideal pulmonary conduit.

The limited lifespan of all currently available conduits leads to repeat operations and interventional procedures in many children. Each reoperation entails considerable risk to life, expenditure and compromised quality of life as the conduit degenerates. The ideal conduit should be available freely, inexpensive, require no anticoagulation, be resistant to infection, free from thromboembolism, have no gradients or regurgitation and have unlimited durability. This review explores various options as surgeons and researchers endeavor to develop the ideal conduit--which will fulfill all of the above-mentioned criteria. Various currently available conduits are analyzed. Special emphasis is given to tissue-engineered valves and percutaneous valve implantations.

Animals↗
PubMed2001

Current medical management of valvular heart disease.

Drug therapy plays a key role in the management of valvular heart disease, though in many cases it does not alter its course or delay the need for surgery. The importance of drug therapy lies in stabilizing the patient's condition when the disease is due to abnormal valve structure, and in treating the underlying condition when the condition is due to a functional abnormality. Drug therapy also lowers the risk of bacterial endocarditis and rheumatic fever.

Aortic Valve Insufficiency↗
PubMed2000

Mitral valve replacement with small-sized tilting-disc mechanical prostheses may lead to moderate stenosis.

BACKGROUND: Analyzing the hemodynamics of small-sized tilting-disc mechanical prostheses implanted in the mitral position. METHODS EXPERIMENTAL DESIGN: this is a retrospective study. The mean follow-up of patients was 114+/-27 months (range 68-152 months). SETTING: departments of Cardiovascular Surgery and Cardiology in a general community hospital Patients: this study includes 9 survivors of 17 patients undergoing mitral valve replacement with this type of device between May, 1982 and July, 1991. INTERVENTIONS: all subjects underwent mitral valve replacement with size 25 mm Sorin tilting-disc mechanical prostheses. MEASURES: all patients underwent transthoracic echocardiography. Five consenting patients also underwent transoesophageal echocardiography. The following parameters were measured: peak gradient, mean gradient, peak velocity, mean velocity, pressure half-time and Doppler area. RESULTS: The ejection fraction was 50% or more in all patients. The following mean results were obtained: peak gradient: 17.4+/-2.5 mmHg; mean gradient: 8.2+/-0.6 mmHg; peak velocity: 2.1+/-0.1 m/sec; mean velocity: 1.43+/-0.06 m/sec; pressure half-time: 135.9+/-29.7 msec; Doppler area: 1.7+/-0.3 cm2. CONCLUSIONS: Valve replacement with Sorin 25 mm tilting-disc mechanical prostheses appears to originate a moderate degree of mitral stenosis and, therefore, we do not recommend their use if at all possible.

Adult↗
PubMed2002

[Cox/maze III procedure combined with mitral valve replacement in treatment of rheumatic mitral valve disease with atrial fibrilation].

OBJECTIVE: To compare the curative effect of Cox/maze III procedure combined with mitral replacement and that of mitral valve replacement (MVR). METHODS: Fifty-six patients suffering from rheumatic heart disease with atrial fibrillation (AF) were treated by Cox/maze III procedure combined with MVR (maze group). Another 56 age, sex, and heart function-matched patients with the same diagnosis underwent MVR alone during the same period. Warfarin was administered after operation in both groups. Comparison of operative complication and curative effects was made. RESULTS: The aortic cross-clamp time and cardio pulmonary bypass time (CPB) were longer in maze group than in MVT group (75 +/- 22 min vs 41 +/- 11 min, P < 0.05 and 124 +/- 40 min VS 68 +/- 19 min, P < 0.05). Bleeding happened after the heart reatored beating in 2 patients in maze group and in one patient in MVT group, all these 3 patients responding satisfactorily to hemostasis. The early post-operative mortality was 1.79% (1/56) in both groups. In maze group, AF disappeared in all patients but one who had node rhythm. Normal sinus rhythm was restored in 98.18% of the patients (54/55). Atrial contractility was restored in all patients with sinus rhythm. One year after operation, 98.18% patients' cardiac function changed to grade and 1.82% changed to grade II. In MVR group AF disappeared after operation temporarily for 24 hours in 7 patients and re-appeared, and AF disappeared in one patients for 2 years so far. One year after operation, the cardiac function of 94.6% patients in MVR group changed to grade I, of 3.6% patients to grade II, and of 1.8% patients to grade III. No serious hemorrhage relate d to anticoagulant therapy happened. One patient in MVR group suffered from hemiplegia due to cerebral embolism. The late mortality was 1.8% on maze group amd 3.6% in MVR group. CONCLUSION: Cox/maze III procedure combined with NVR is safe and effective in treating rheumatic heart disease with AF.

Adult↗
PubMed2004

[Bio-artificial organs: cardiac applications].

The most important bio-prosthetic organs in cardiovascular medicine are artificial heart valve prostheses and blood pumps. Cardiac valve prostheses can be divided in 'mechanical' and 'biological' valves. Mechanical prostheses are entirely made of artificial materials and require a meticulous anticoagulation therapy. The biological heart valves or heterografts (the allo- and autografts are not considered in this issue) are made of fixed or crosslinked biological tissue and therefore anticoagulation of the patient is not necessary. Actual mechanical heart valves consist of a titanium ring in which one or more leaflets made of pyrolite carbon assure the opening and closing mechanism. Biological heart valves are made of fixed porcine aortic valves or of fixed bovine pericardium. Both tissues can be mounted on a metal frame (so-called 'stented valves') or they can lack this structure ('stentless valves'). The problem with these biological valves is the durability: during the years they start degenerating or calcifying. To prevent this, recent biological heart valves are treated with an anti-mineralisation procedure. Since recent years intense research is ongoing to develop a living heart valve by 'tissue engineering'. When the entire heart fails, and pharmacological treatment remains inadequate or a heart transplantation is not immediately possible, artificial blood pumps are implanted. In general, two categories of blood pumps can be distinguished: displacement and rotary blood pumps. Displacement pumps move a certain amount of blood by the movement of a flexible membrane. This movement is pneumatically or electrically driven and requires an extensive installation: artificial ventricles, tubing, motors, pneumatic systems and driving consoles. Examples in clinical use are: Novacor, Heart Mate, Thoratec, Medos/HIA. Recent developments focus on miniaturisation and endovascular implantation. The rotary blood pumps are well suited for these purposes. They can be either axial, diagonal or radial pumps. A promising new develoment is the Impella pump: this is an axial flow pump having a diameter of 4 mm, which is implanted, inclusive the electrical motor, in the failing heart and delivers an output of 2 to 10 liter/minute. Clinical testing of this device is ongoing.

Animals↗
PubMed2004

Intraoperative transesophageal echocardiography after aortic valve replacement does not predict subsequent transvalvular gradients.

BACKGROUND AND AIM OF THE STUDY: Intraoperative transesophageal echocardiography (TEE) can be used to assess gradients after aortic valve replacement (AVR). However, altered cardiac output after weaning from cardiopulmonary bypass, dynamic changes in valve function early after surgery, and limitations in transducer alignment may compromise the ability to predict valve hemodynamics on follow up. The study aim was to compare gradients on intraoperative TEE immediately after AVR with gradients on transthoracic echocardiography (TTE) after two to four months. METHODS: Among 90 patients who underwent AVR between September 2002 and April 2003, 31 had both intraoperative 'post-pump' TEE, including transaortic gradients, and TTE at two to four months after surgery. Mean and peak transvalvular gradients were compared between time periods, and a receiver operator curve (ROC) was constructed to test the ability to predict a mean gradient >15 mmHg (upper quartile of patients) on follow up. RESULTS: There was no discernable correlation between mean gradient on intraoperative imaging and at follow up (R2 = 0.09; p = 0.11); for peak gradient there was a statistically significant but extremely weak correlation between time points (R2 = 0.17; p = 0.02). A ROC revealed very poor prediction of high mean gradient on follow up based on mean gradient on intraoperative TEE (area under curve 0.63). CONCLUSION: Gradients on intraoperative TEE immediately after AVR do not correlate with later gradients on TTE. The mean gradient on intraoperative TEE holds no useful predictive value for a high mean gradient at follow up.

Aged↗
PubMed2002

The On-X prosthetic heart valve at five years.

BACKGROUND: Multicenter clinical trials were conducted in Europe and North America to evaluate the performance of the On-X bileaflet heart valve prosthesis (Medical Carbon Research Institute, Austin, TX). METHODS: A total of 532 patients underwent implantation, 303 for aortic valve replacement (AVR) and 229 for mitral valve replacement (MVR), at 20 centers from September 1996 to July 2001. The study followed the guidelines of the AATS/STS. Mean follow-up was 23 months (total 1024 patient-years; maximum 5 years). Poolability analysis was performed to show the equivalence of the populations. RESULTS: Patients and results were found to be similar and poolable. Freedom from adverse events at 2 years in the study were as follows: thromboembolism, 96.0% for AVR patients and 96.3% for MVR; thrombosis, 100% for AVR and 100% for MVR; bleeding events, 96.6% for AVR and 95.7% for MVR; and overall mortality, 95.2% for AVR and 92.4% for MVR. Median lactate dehydrogenate levels were in the normal range for AVR and MVR patients at all intervals. At 1 year, AVR echocardiographic results for the 19 to 25 valves, respectively, ranged from 1.5 to 2.8 cm2 for effective orifice area and 9.2 to 4.7 mm Hg for mean gradient, and MVR effective orifice area by pressure half-time was 2.8 cm2 and mean gradient was 4.2 mm Hg. CONCLUSIONS: The two trials have given similarly excellent results for the On-X valve.

Adult↗
PubMed2001

Emergency redo mitral valve replacement in a 27-year-old pregnant female with a clotted prosthetic mitral valve, preoperative fetal demise and postoperative ventricular assist device: a case report.

A 27-year-old Laotian woman with a St Jude mechanical mitral valve became pregnant, requiring a change in her anticoagulant after the first trimester when her warfarin sodium (coumadin) was replaced with enoxaparin sodium (lovenox). Her prosthetic valve clotted and became dysfunctional. She was 16 weeks pregnant and was taken to the operating room for emergency surgery for replacement of the valve. The fetus had not been viable for 1-2 weeks, but still remained in utero. The clotted valve was replaced with another St Jude valve of a slightly smaller diameter (27 mm). The patient could not be weaned from bypass so a right ventricular assist device (RVAD) was inserted. The patient was weaned from the RVAD after 2 days of support. Two days following removal of the RVAD the fetus spontaneously aborted. The patient had a long, complicated hospital course and was discharged 3 months later. She subsequently died 4 months after discharge of a cerebral hemorrhage from excessive anticoagulation.

Adult↗
PubMed2002

Aortic cusp extension valvuloplasty for rheumatic aortic valve disease: midterm results.

BACKGROUND: The surgical management of rheumatic aortic insufficiency in the young remains problematic owing to the drawbacks of prosthetic valve replacement at this age. In young foreign patients, for whom long-term anticoagulation therapy is unavailable, we have used a glutaraldehyde preserved autologous pericardium cusp extension technique to repair rheumatic aortic valve insufficiencies resulting from cusp retractions. METHODS: From September 1992 to December 2000, 89 consecutive patients with a mean age of 16 +/- 5 years underwent triple pericardial aortic cusp extension valvuloplasty. Eighty patients had pure aortic insufficiency, 9 had mixed aortic disease. Twenty-nine patients (33%) had isolated aortic valve disease and 60 patients (69%) had combined aortic and mitral valve disease with significant tricuspid valve disease in 21 (24%). Aortic repair consisted of free edge aortic cusp extension using three rectangular strips of glutaraldehyde stabilized autologous pericardium. Twenty-nine patients (33%) underwent an isolated aortic repair, 39 patients (44%) underwent combined aortic and mitral procedures (34 mitral repairs, 3 mitral homografts, and 2 prosthesis replacements), and 21 patients (23%) underwent a triple valve repair. RESULTS: The hospital mortality was 2.2%. Primary failure of the aortic repair requiring immediate reoperation occurred in 2 patients. During follow-up (mean of 62 +/- 22 months) 1 patient died and 7 underwent redo valvular surgery. At 5 years the actuarial survival rate was 96.4%, and 92.1% of the patients were free from redo valvular surgery. At 7 years 90% of the patients were free from valve-related complications. Among the 76 patients free from redo valvular surgery at follow-up, 6 had deterioration of the repair resulting in grade II aortic and mitral insufficiencies. CONCLUSIONS: Our midterm results of glutaraldehyde stabilized autologous pericardial aortic cusp extension are encouraging and suggest that this technique should be considered as a viable alternative palliative procedure in a young rheumatic population, allowing for growth of the annulus and delaying to a less critical period the need for the lifelong anticoagulation therapy required for a prosthetic mechanical valve.

Adolescent↗
PubMedDate not supplied

Use of three-dimensional sonomicrometry to study the motion of the mitral valve.

To develop an anatomically correct mitral valve prosthesis, one needs to study the dynamics of the mitral valve apparatus in vivo. The authors used three-dimensional (3D) sonomicrometry and custom visualization software to develop a system to study the mitral valve. Sixteen ultrasonic transducers each were implanted into the hearts of pigs under cardiopulmonary bypass. Four of these crystals were affixed to the base and apex of both papillary muscles, four were attached to the free edge of the anterior and posterior leaflets where the main chordae attach, six were placed around the mitral annulus, and two were affixed to the epicardial wall. The digital sonomicrometer system sequentially fired each transducer and listened for an ultrasound signal at the other 15. This process was repeated so that all 16 transducers were sequentially fired, and each cycle of 16 was repeated 200 times/sec. The matrix of distances obtained between all the combinations of pairs of the 16 transducers was converted to x, y, z coordinates, the shape of the mitral valve apparatus was reconstructed in 3D on a graphics computer, and the valve's motion was analyzed over several cardiac cycles. The authors conclude that mapping of the mitral valve apparatus in pigs by 3D sonomicrometry provides quantitative measurements that can aid in the design of a mitral valve prosthesis that closely replicates the anatomy and function of the natural valve.

Animals↗