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At least 613 records · Page 34Linked to original sources
PubMed1989

[Ten-year experience with the St. Jude Medical valve replacement: comparison with the Björk-Shiley valve].

St. Jude Medical (SJM) valve replacement in 995 patients with a cumurative follow-up period of 2,730 patient-years was compared with the Björk-Shiley (BS) valve replacement in 406 patients, who had followed up for 3,779 patient-years (pt-yr). The overall survival rates of aortic, mitral, and double valve replacement with SJM (and BS) at 10 years were 60.6% (80.0%), 89.6% (81.9%), 90.3% (73.9%), respectively. The linealized incidences of thromboembolism, valve thrombosis, prosthetic valve endocarditis, anticoagulation-related hemorrhage, significant hemolysis, and structural failure in SJM (and BS) were as follows: 1.32%/pt-yr (0.82%/pt-yr), 0.11%/pt-yr (0.21%/pt-yr), 0.18%/pt-yr (0.08%/pt-yr), 0.04%/pt-yr (0.24%/pt-yr), 0.18%/pt-yr (0.13%/pt-yr), and 0%/pt-yr (0.05%/pt-yr), respectively. Reoperation (explant and re-replacement or suture repair) was required in 10 SJM patients (0.37%/pt-yr) and in 14 BS cases (0.37%/pt-yr). Actuarially over 97% of patients were free of valve-related mortality at 10 years in both groups. From these results we conclude that both SJM and BS valves are equally excellent cardiac valve prosthesis. Considering the better hemodynamic characteristics and technical feasibility, we have thus far adopted SJM, rather than BS, as a first prosthesis of choice.

Adult↗
PubMed1981

Congenitally bicuspid aortic valve causing severe, pure aortic regurgitation without superimposed infective endocarditis. Analysis of 13 patients requiring aortic valve replacement.

Although stenosis and infective endocarditis are commonly appreciated complications of the congenitally bicuspid aortic valve, pure severe aortic regurgitation complicating this congenital malformation, unassociated with either stenosis or infection, is not well recognized. Among 189 patients who had aortic valve replacement at the National Heart, Lung, and Blood Institute because of isolated pure aortic regurgitation, the congenitally bicuspid aortic valve, never the site of infective endocarditis, was responsible for the aortic regurgitation in 13 (7 percent). This report describes certain clinical and morphologic findings in 13 men, aged 26 to 65 years (mean 43), who required aortic valve replacement because of severe aortic regurgitation secondary to a noninfected, nonstenotic congenitally bicuspid aortic valve. Although not generally recognized, the noninfected congenitally bicuspid aortic valve is an important cause of pure aortic regurgitation severe enough to warrant aortic valve replacement.

Adult↗
PubMed1991

Comparison of allografts and prosthetic valves when used for emergency aortic valve replacement for active infective endocarditis.

Aortic valve replacement (AVR) using allografts is an established method of treating aortic valve disease. It is uncertain, however, whether the increased technical demands of allograft AVR can be justified in emergency operations. This study reports 15 patients treated between 1987 and 1990 for acute bacterial or fungal endocarditis involving the aortic valve. Patients underwent emergency AVR because of severe congestive failure, overwhelming sepsis or cerebral emboli. Eight patients received prosthetic valves (group I: 4 mechanical, 4 porcine) and 7 received human allografts (group II: 5 aortic and 2 pulmonary). The groups were comparable in age (group I, 55 years; group II, 51 years), intravenous drug abuse (group I, 1; group II, 3), and previous AVR (group I, 3; group II, 2). One group I and 4 group II patients had septal abscesses. Additional procedures in group I included mitral valve replacement (2), tricuspid valve replacement (1) and aortic root replacement (1). Additional procedures in group II were mitral valve repair (1), root replacement (1), atrial septal defect closure (1) and aortocoronary bypass (1). Mean bypass times (group I, 189 minutes; group II, 204 minutes) and cross-clamp times (group I; 108 minutes; group II, 121 minutes) were similar. Operative deaths occurred in 4 of 8 group I and 1 of 7 group II patients. All surviving patients have been successfully followed (group I, 28 months; group II, 18 months). No group I patient has required reoperation. One group II patients required reoperation for recurrent infection affecting the allograft, and another group II patient died 10 months postoperatively from noncardiac causes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Risk of repeat mitral valve replacement for failed mitral valve prostheses.

BACKGROUND: Advances in tissue prosthetic valve design and manufacturing have stimulated renewed interest in the use of biological valves in younger patients. This approach, however, risks reoperation. We therefore reviewed our recent experience with repeat mitral valve replacement to better define its contemporary risks. METHODS: Using a computerized database, we identified and compared 106 patients undergoing repeat mitral valve replacement with 562 control patients undergoing primary mitral valve replacement between January 1993 and December 2000 at our institution. RESULTS: There were no significant differences between repeat and primary surgery groups with respect to age (mean 66 +/- 12 vs 64 +/- 13 years), gender distribution (women 65% vs 64%), preoperative functional class, ejection fraction, or active endocarditis (6.6% vs 3.4%). The indication for reoperation in the repeat group was structural dysfunction in 49 patients (46%), paravalvular leak in 21 patients (20%), nonstructural dysfunction in 11 patients (10%), and progression of other native valve disease in 8 patients (8%). Prior prostheses were mechanical in 46 patients (43%). Mean time to reoperation was 11.5 +/- 7.1 years. There were 5 deaths out of 106 patients in the repeat group (4.7%) and there were 23 deaths out of 562 patients in the control group (4.1%) (p = NS). Multivariate analysis identified prior myocardial infarction (p = 0.014, odds ratio 2.9) and nonelective surgical status (p = 0.004, odds ratio 2.3) as significant predictors of operative mortality. CONCLUSIONS: The risk of repeat mitral valve replacement was low suggesting that there should be less reluctance to recommend patients choose a bioprosthesis over a mechanical prosthesis. Given the expected durability of current designs, bioprosthetic use may be explored in younger patients without subjecting those individuals to excessive risk.

Aged↗
PubMed2005

Up to 16 years follow-up of aortic valve reconstruction with pericardium: a stentless readily available cheap valve?

OBJECTIVE: There is lack of information regarding the long-term behavior of aortic valve reconstruction with pericardium (AoR). A 16-year follow-up is reported here. METHODS: Between 1988 and 1995, 92 consecutive patients had AoR with bovine (Group I, n=27) or glutaraldehyde-treated autologous pericardium (Group II, n=65). The mean age was 30 years (range 12-68). There were 65% males, 92% in sinus rhythm, 84% had rheumatic etiology and 36% had 'other valve' surgery. Mitral valve replacement with a mechanical prosthesis is a contraindication to the operation. RESULTS: Hospital mortality was 2%. The reconstructed aortic valve performed well with excellent hemodynamics. The mean follow-up interval was 10.5+/-4 years, range 9-16 years (longer for group I,12 versus 10 years) with 4% late deaths and seven patients lost to follow-up. Survival rate was 85+/-4%. There were no episodes of thromboembolism. Freedom from reoperation for the whole group was 68+/-5% at 10 years and 47+/-6% at 16 years. For group I, it was 68+/-9% at 10 years and 48+/-10% at 16 years, while for group II it was 72+/-6 and 45+/-8% at 10 and 15 years, respectively. Excluding endocarditis (one in group I and seven in group II) and 'other' reasons for reoperation (two in group I and three in group II), the freedom from structural valve degeneration (SVD) at 10 and 16 years was 78+/-1 and 55+/-10% for group I. For group II, it was 80+/-5% at 10 years and 58+/-9% at 15 years. The mean interval at which the valve degenerated was 8.8 years+/-3.6 and did not differ between the two groups. CONCLUSIONS: AoR is feasible with good hemodynamics, low mortality and thromboembolic rate. Its behavior at 10 years is comparable to that of stentless aortic valve bioprosthesis. It can be performed with either xenopericardium or glutaraldehyde-treated autologous pericardium, but the latter has the advantage of being inexpensive and readily available.

Adolescent↗
PubMed2005

Intermediate results of isolated mitral valve replacement with a Biocor porcine valve.

BACKGROUND: We analyzed the intermediate experience, survival, and prosthetic complications of patients who received the Biocor valve, a new-generation porcine valve, in the mitral position. METHODS: At the University of Padua, between May 1992 and January 2004, 154 consecutive patients (102 female and 52 male patients; mean age, 72.3 +/- 6 years; age range, 37-86 years) received 158 mitral Biocor prostheses (Biocor Industria e Pesguisa Ltda, Belo Horizonte, Brazil). Thirty-five percent of the patients had previous mitral operations, 24% had coronary artery bypass grafting, and 34.6% had other procedures. Median preoperative New York Heart Association class was III. Echocardiography was performed in 75% of the long-term survivors. Follow-up included 609.4 patient-years and was 100% complete, with a median time of 4 patient-years (range, 0.02-11.3 years). At 8 years, 20 (14%) of 142 operative survivors were still at risk. RESULTS: Early mortality was 13.6%. According to univariate analysis, New York Heart Association class III to IV, ejection fraction of less than 40%, urgency, male sex, and coronary artery bypass grafting were significant perioperative risk factors. Eight- and 10-year actuarial survival was 51.1% +/- 5.6% (40 deaths). Eight-year actuarial freedom from valve-related death, thromboembolism, anticoagulant-related hemorrhage, endocarditis, paravalvular leak, and valve-related complications were 85.2% +/- 5%, 85.7% +/- 4.4%, 92.6% +/- 3.7%, 94.1% +/- 3%, 91.8% +/- 3%, and 70.2% +/- 5.7%, respectively. Freedom from structural valve deterioration was 100%. Actual freedom from reoperation was 93.2% +/- 2.2%. By Doppler echocardiography, the peak and mean transprosthetic gradients were 15 +/- 5 mm Hg and 6.3 +/- 3 mm Hg, respectively (mean follow-up, 4.2 +/- 2.7 years). CONCLUSION: At intermediate follow-up, the Biocor prosthesis in the mitral position showed excellent results in terms of valve durability when compared with other second-generation tissue valves.

Adult↗
PubMed1998

Aortic homografts versus mechanical valves in aortic valve replacement in young patients: a retrospective study.

BACKGROUND: Whether aortic homografts (AH) or mechanical devices (MD) are the valves of choice for aortic valve replacement in young patients (age 20 to 50 years) is unclear. Hence, we examined all aortic valve replacements performed with AH and MD in a retrospective study. METHODS: Between 1988 and 1995, 45 patients (mean age, 38.6+/-8.5 years) underwent aortic valve replacement with an AH and 40 patients (mean age, 42.0+/-7.2 years) with an MD. Patients' demographic data were comparable in all respects, except acute endocarditis, which was an absolute indication for the use of an AH. RESULTS: The mean follow-up time was 51.7+/-22.6 months for AH versus 44.6+/-26.9 months for MD (not significant). There were significant differences in postoperative outcome among the two groups (p < or = 0.05): perioperative death (4 versus 0 for AH and MD, respectively); reoperation (8 for AH versus 0 for MD); and endocarditis (5 versus 0 for AH and MD). There were higher incidences of embolism (2 versus 0) and hemorrhage (2 versus 0) in MD compared with AH. Only late death was comparable among the two groups with 5 patients in each group. CONCLUSIONS: The mechanical valves in our midterm follow-up are superior to homografts. However, embolic and hemorrhagic complications in MD are continuously impending and cumulative during a long-term follow-up. The surprisingly high rate of endocarditis in the AH group is only partly caused by the indication: 2 cases were recurrent, but there were also 2 new onsets of endocarditis. In 4 cases structural deterioration was responsible for reoperation. Aortic valve replacement with aortic homografts showed a rather unfavorable midterm outcome in this selected group of young patients. A surprisingly high rate of graft endocarditis and structural deterioration led to subsequent reoperations. Although our results with mechanical valves are satisfying, embolism and hemorrhage are impending risk factors for many years to come in these young patients.

Adult↗
PubMed2002

Obstruction of St Jude medical valves in the aortic position: a consideration for pathogenic mechanism of prosthetic valve obstruction.

Between 1995 and 2000, 8 patients with St. Jude Medical (SJM) valves in the aortic position required 9 redo valve replacement for prosthetic valve obstruction. Obstruction of the prosthetic valve was diagnosed by simultaneous echocardiography and cineradiography, and process of restricted leaflet movement that progressed to hemodynamic impairment was observed by serial studies in three recent patients. An oral anticoagulation was considered to be adequate in all patients except one patient who had withdrawal of warfrain. Pannus was the sole cause of valve obstruction in seven events in 6 patients, and both thrombus and pannus in 2 patients. Pannus overgrowth was found on the inflow aspect of the SJM valve, and involved the ends of the straight edge of the leaflets over pivot guards. These results suggest that pannus might play the primary role in development of obstruction of aortic SJM valves in patients on adequate oral anticoagulation.

Aged↗
PubMed1997

Survival and cause of death after mitral valve replacement in patients aged 80 years and over: collective results from the UK heart valve registry.

OBJECTIVE: Over the last decade there has been an increasing number of patients aged 80 years and over undergoing heart valve replacement. However, literature on the outcome of mitral valve replacement (MVR) in this age group is still limited. METHODS: We conducted the present study by analysing data extracted from the UK Heart Valve Registry. From January 1986 to December 1994, 86 patients underwent isolated MVR and 10 underwent combined MVR with aortic valve replacement (AVR) and were reported to the Registry. RESULTS: The 30 day mortality was 10.4% (9/86) in the MVR group and 10% (1/10) in the MVR and AVR group. The actuarial survival was 79.8, 64.1 and 40.7% at 1, 3 and 5 years, respectively, in the MVR group. Of the 10 early (30 day) deaths, 8 were due to cardiac reasons and 19 of the 28 late deaths were due to non-cardiac reasons. A total of 55 (57.2%) patients received a bioprosthetic valve implant and 41 (42.8%) patients received a mechanical valve implant. There was no difference in survival between the two groups. CONCLUSIONS: The above results suggest that MVR in octogenarians produces a satisfactory early postoperative outcome and moderate medium-term benefit. There is no difference in survival between patients receiving bioprosthetic and patients receiving mechanical valve implants.

Actuarial Analysis↗
PubMed1998

Clinical, echocardiographic, and pathologic features of aortic wall dehiscence of porcine bioprosthetic valves: a cause of rapidly progressive mitral regurgitation and heart failure after bioprosthetic mitral valve replacement.

The aim of this study was to define the clinical, echocardiographic, and pathologic correlates of commissural dehiscence of aortic wall from the stent post of the porcine bioprostheses in the mitral position. This form of valve degeneration was found in 5 of 23 explanted mitral bioprostheses. A thickened, separated aortic wall at multiple commissural sites along with other evidence of valve degeneration was identified in the three patients who had chronic congestive heart failure. A large dehiscence at a single commissural site with otherwise normal valve morphology was present in the two patients who had acute heart failure. Two dimensional/Doppler echocardiography showed a prolapsing or a flail anteriorly positioned leaflet and an eccentric posteriorly directed mitral regurgitation jet in all patients. These echocardiographic findings in patients with a porcine bioprosthetic mitral valve should suggest commissural dehiscence from the aortic wall as a possible mechanism of valve failure. Exclusive involvement of the porcine aortic bioprosthesis placed in the mitral position along with involvement of strut of the bioprosthesis facing the aortic root in all cases suggests excessive hemodynamic stress on the valve in the mitral position and in particular on the anteriorly placed strut as the potential cause of this form of valve degeneration.

Aged↗
PubMed2001

Aortic valve replacement with pericardial valves in patients with small aortic roots. Clinical results in a consecutive series of patients receiving 19 and 21 mm prostheses.

OBJECTIVE: To determine how second generation pericardial valves perform in patients with small aortic roots. DESIGN: Ninety patients who underwent isolated aortic valve replacement (AVR) with 19 or 21 mm Mitroflow or Carpentier-Edwards (Perimount) valves between 1989 and 1996 were studied. Mean age was 78 years. Concomitant coronary bypass surgery was performed in 41%. RESULTS: Thirty-day mortality was 5.6%. Ninety-seven percent had acceptable transprosthetic mean pressure gradients (25 mmHg or less) 1 week after surgery. Follow-up was 100% complete and 76% of the patients were alive after a mean of 5 years. There was no structural valve failure or valve thrombosis. One patient required reoperation for perivalvular leak. Four patients had transient ischemic attacks and seven had strokes. These figures are, however, within the expected range for the age. CONCLUSION: Second generation pericardial valves perform well in elderly patients with small aortic roots. Postoperative hemodynamics are acceptable, valve durability of up to 8 years adequate, and the clinical results good, considering the age of the patients.

Aged↗
PubMed1997

25 years of aortic valve replacement using mechanical valves. Risk factors for early and late mortality.

This study describes the changes that have taken place in patient characteristics in 25 years of aortic valve replacement using mechanical valves, and looks for risk factors for early and late mortality. During this period, 1449 mechanical valves were implanted. Overall early mortality (< 30 days) was 5.3% and for aortic valve replacement without concomitant procedures 3.9%. Overall survival rates at 5, 10 and 15 years were 80%, 63% and 49%, respectively. Despite an increased proportion of higher risk patients (older age, more reoperations, more concomitant coronary bypass surgery) survival rates improved throughout the study period. Early mortality was related to an early year of operation, urgency, reoperation and concomitant surgery to the tricuspid valve or ascending aorta. Late mortality was higher for patients of older age, with an early year of operation, male gender, concomitant coronary bypass surgery, mitral valve surgery or replacement of the ascending aorta. Aortic regurgitation did not have a major influence on early nor late mortality. The improvement in early and late mortality in more recent years was largely the result of the introduction of cardioplegia. A changing, non-proportional effect was observed for several risk factors during the follow-up period. This study illustrates the changes and improvements in medical care that have taken place in patients requiring aortic valve replacement.

Aortic Valve↗
PubMed1984

Bioprosthetic valve replacement in children--long-term follow-up of 135 isolated mitral valve implantations.

From August 1976 to January 1980, 135 patients, age 20 years or younger (mean 13.7 +/- 3.46 years), received 37 Hancock, 4 Angell-Shiley and 94 Carpentier-Edwards prostheses as a mitral valve substitute. Only patients who had isolated mitral valve replacement were included in this study. All patients were in NYHA class III and IV and 22 had acute rheumatic valvulitis. Approximately half of the patients had mitral regurgitation. Early mortality was 4.4% (6 patients). The cumulative follow up period was 356 patient-years. Thirty-eight patients died late (10.7% per patient year), of which 26 (7.3% per patient year) died of valve related causes. Sixty-four patients (18% per patient year) had mitral valve replacement for a degenerated bioprosthesis. Eleven patients with degenerating prostheses died without surgery and 5 await reoperation. Hence, structural valve failure occurred in 80 instances (22.5% per patient year). Actuarial survival at 7 years was 50%. Complication-free valve survival was 15%. Only 7 patients (5.2%) remain with their original prostheses, free from degeneration. Our experience confirms that bioprostheses have a prohibitive failure rate in children. Degenerating valves should be replaced early rather than late.

Adolescent↗
PubMed1997

Minimally invasive cardiac valve surgery improves patient satisfaction while reducing costs of cardiac valve replacement and repair.

OBJECTIVE: This study compares the quality of valve replacement and repair performed through minimally invasive incisions as compared to the standard operation for aortic and mitral valve replacement. SUMMARY BACKGROUND DATA: With the advent of minimally invasive laparoscopic approaches to orthopedic surgery, urology, general surgery, and thoracic surgery, it now is apparent that standard cardiac valve operations can be performed through very small incisions with similar approaches. METHODS: Eighty-four patients underwent minimally invasive aortic (n = 41) and minimally invasive mitral valve repair and replacement (n = 43) between July 1996 and April 1997. Demographics, procedures, operative techniques, and postoperative morbidity and mortality were calculated, and a subset of the first 50 patients was compared to a 50-patient cohort who underwent the same operation through a conventional median sternotomy. Demographics, postoperative morbidity and mortality, patient satisfaction, and charges were compared. RESULTS: Of the 84 patients, there were 2 operative mortalities both in class IV aortic patients from multisystem organ failure. There was no operative mortality in the patients undergoing mitral valve replacement or repair. The operations were carried out with the same accuracy and attention to detail as with the conventional operation. There was minimal postoperative bleeding, cerebral vascular accidents, or other major morbidity. Groin cannulation complications primarily were related to atherosclerotic femoral arteries. A comparison of the minimally invasive to the conventional group, although operative time and ischemia time was higher in minimally invasive group, the requirement for erythrocytes was significantly less, patient satisfaction was significantly greater, and charges were approximately 20% less than those in the conventional group. CONCLUSIONS: Minimally invasive aortic and mitral valve surgery in patients without coronary disease can be done safely and accurately through small incisions. Patient satisfaction is up, return to normality is higher, and requirement for postrehabilitation services is less. In addition, the charges are approximately 20% less. These results serve as a paradigm for the future in terms of valve surgery in the managed care environment.

Adult↗
PubMed1997

Allograft valves for aortic and mitral valve replacement.

Allograft valves have been used in cardiac valve replacement for 35 years. During much of this time, certain centers have used allograft aortic valves for aortic valve replacement and have reported excellent long-term results. After an initial period of failure using allograft mitral valves for mitral valve replacement, the technical problems of papillary muscle dehiscence and mitral regurgitation appear minimized by current investigators who now report encouraging early results. The current status of allograft use for aortic and mitral valve replacement is reviewed.

Aortic Valve↗
PubMed1988

A review of surgery for acquired tricuspid valve disease, including an assessment of the stented semilunar homograft valve, and the results of operation for multivalvular heart disease.

A total of 246 operations were performed in 230 patients for correction of acquired tricuspid valve disease. All but three of the patients had multivalvular heart disease. There was an 11% hospital mortality which fell to 7% in the later era (1973-82). Mortality was similar for tricuspid annuloplasty and tricuspid replacement and for double and triple valve surgery. On multivariate analysis the incremental risk factors for hospital death were extreme functional disability (Class V), being of Caucasian race, and having a high cardiothoracic ratio (CTR). Actuarial survival was 58% at 9 years postoperative. The incremental risk factors for late death were prior cardiac surgery, age at operation greater than or equal to 55 years, and advanced functional disability (Classes IV, V). The actuarial incidence of significant tricuspid incompetence following annuloplasty was 12% at 3 years, and following stented homograft semilunar valve replacement was 6% at 3 years and 24% at 8 years. Severe homograft valve incompetence was always associated with recurrent left-sided valve lesions or residual pulmonary hypertension. It is concluded that a homograft valve is a superior form of tricuspid valve replacement.

Adolescent↗
PubMed1992

Bovine pericardium versus porcine aortic valve: comparison of tissue biological properties as prosthetic valves.

The choice of a bioprosthetic valve substitute remains controversial with the major concern being primary tissue failure after implantation. We compared biological properties of the two most frequently used bioprosthetic valve materials, bovine pericardium and porcine aortic valve, before and 90 days after subcutaneous implantation in rats. Before implantation, tissue collagen and water content were measured in nine pieces of bovine pericardium and porcine valves, each fixed in 0.625% glutaraldehyde; calcium, tissue collagen, and water content were measured in another nine pieces of the same tissues after 90 days' implantation. Bovine pericardium had higher collagen content than that of porcine valve (hydroxyproline, 7.98 +/- 0.05* vs. 4.56 +/- 0.02 micrograms/mg, dry weight) but lesser water content (72.16 +/- 3.22%* vs. 87.36 +/- 1.62%) before implantation (*p < 0.001, mean +/- SD, t test); after implantation, bovine pericardium still maintained higher collagen content (hydroxyproline, 4.89 +/- 0.04* vs. 2.61 +/- 0.06 micrograms/mg, dry weight) but contained the same amount of water (60.24 +/- 5.08% vs. 61.43 +/- 9.00%) and calcium (214.43 +/- 34.34 vs. 199.33 +/- 53.44 micrograms/mg, dry weight) (*p < 0.001, mean +/- SD, t test). We conclude that bovine pericardium has superior intrinsic biological properties for prosthetic valve manufacture. With proper integration of properties and design it will in some applications be superior to the porcine aortic valve.

Animals↗
PubMedDate not supplied

Comparison of exercise hemodynamics among nonstented aortic bioprostheses, mechanical valves, and normal native aortic valves.

BACKGROUND: While aortic valve prostheses are known to perform well at rest, few studies have examined them under stress. We compared stress hemodynamics of mechanical valves and nonstented porcine valves in the aortic position to that of normal native aortic valves. METHODS: Dobutamine echocardiography was used to assess mean and peak gradients and effective orifice area index (EOAI) at rest and exercise in patients with the Toronto Stentless Porcine Valve (SPV) (n = 13, mean implant size 25.7 mm), Sorin Bicarbon mechanical valve (SOR) (n = 11, mean implant size 24.5 mm), and patients with normal native aortic valves (NOR) (n = 10). Dobutamine infusion was started at 5 micron/kg per minute, and increased by increments of 5 micron/kg per minute until the target heart rate was achieved or until a maximal dose of 40 micron/kg per minute. RESULTS: At rest and exercise, respectively, cardiac output (L/min) was 5.2 and 10.4 for Toronto SPV; 7.4 and 13.5 for SOR; and 4.6 and 11.2 for NOR. Measured EOAI (cm2) was 1.1+/-0.2 and 1.15+/-0.2 for TORONTO SPV; 1.60+/-0.3 and 1.58+/-0.3 for SOR; and 1.45+/-0.2 and 1.46+/-0.2 for NOR. Mean gradients (mmHg) were 5.48+/-1.1 and 5.83+/-0.9 for TORONTO SPV; 5.26+/-0.8 and 11.3+/-1.8 for SOR; and 1.54+/-0.4 and 2.18+/-0.7 for NOR. Peak gradients (mmHg) were 11.9+/-2.0 and 21.0+/-3.7 for TORONTO SPV; 10.79+/-1.7 and 25.9+/-3.4 for SOR; and 2.38+/-0.9 and 6.1+/-2.3 for NOR. CONCLUSIONS: Although the mechanical group (SOR) had larger measured EOAI, the greater increase in gradients with exercise in this group suggests that the TORONTO SPV is less obstructive to flow.

Aortic Valve↗