Xu Yu Jin

Effects of Valve Substitute on Changes in Left Ventricular Function and Hypertrophy After Aortic Valve Replacement

BACKGROUND Residual left ventricular hypertrophy adversely affects long-term outcome after aortic valve replacement. A stentless biological valve in the aortic position has been shown to offer a better hemodynamic profile than a stented one. However, it remains to be defined whether this difference is translated into inter-mediate-term effects on left ventricular structure and function. METHODS One hundred thirty-seven patients receiving single aortic valve replacement (52 with concomitant coronary artery bypass graft) were enrolled in this study. Ninety-eight were men, and the mean age was 68 years (range, 55 to 90 years). Of the 137 patients, 39 had an aortic homograft, 72 a Toronto stentless porcine valve, and 26 had a stented porcine or bileaflet mechanical valve, with mean valve size of 25 +/- 2.5 mm (mean +/- standard deviation). Left ventricular muscle mass and function were assessed by M-mode echocardiography performed before and 0.5, 6, 12, 24, and 36 months after operation, and recorded on paper for off-line digitizing. Peak valve prosthesis pressure gradients were quantified by continuous wave Doppler. RESULTS A total of 330 echocardiograms obtained during this study were adequate for computer digitizing. Clinical data, preoperative left ventricular function, and hypertrophy were similar between the three groups. Significant improvement in left ventricular function and major regression of left ventricular hypertrophy had occurred in the entire population by 6 months after operation. Multivariate analysis of variance showed that patients with previous aortic regurgitation had a larger left ventricular cavity size (p < 0.001) and greater mass index (p = 0.001) postoperatively than those with previous aortic stenosis. In addition, peak valvular gradient was lower (p < 0.001), mass index less (p < 0.001), and left ventricular function more normal both systolic, by a greater peak velocity of dimension shortening (p = 0.05) and wall thickening (p = 0.002), and diastolic, by a greater peak velocity of dimension lengthening (p = 0.046), with an aortic homograft or stentless porcine valve compared with a mechanical or stented biological valve. There was no significant difference in peak valve gradient, left ventricular mass index, or function between the aortic homograft and the stentless porcine valve. Age, sex, and concomitant coronary artery bypass graft, as well as aortic cross-clamp time, cardioplegia method, and valve size all proved to be insignificant determinants of postoperative left ventricular hypertrophy or function. CONCLUSIONS In the first 2 years after implantation, the superior hemodynamic performance of aortic homograft and stentless porcine valve appears to result in more extensive regression of ventricular hypertrophy and greater improvement of left ventricular function than occurs with a mechanical or stented biological valve. These findings encourage the use of a stentless biological valve in older patients requiring aortic valve replacement, and a larger scale long-term randomized study of stentless versus stented biological valve or mechanical valve seems warranted.

First permanent implant of the Jarvik 2000 Heart

BACKGROUND Heart failure is a major public-health concern. Quality and duration of life on maximum medical therapy are poor. The availability of donor hearts is severely limited, therefore an alternative approach is necessary. We have explored the use of a new type of left-ventricular assist device intended as a long-term solution to end-stage heart failure. METHODS As part of a prospective clinical trial, we implanted the first permanent Jarvik 2000 Heart--an intraventricular device with an innovative power delivery system--into a 61-year-old man (New York Heart Association functional class IV) with dilated cardiomyopathy. We assessed the effect of this left-ventricular assist device on both native heart function and the symptoms and systemic characteristics of heart failure. FINDINGS The Jarvik 2000 Heart sustained the patients circulation, and was practical and user-friendly. After 6 weeks, exercise tolerance, myocardial function, and end-organ function improved. Symptoms of heart failure have resolved, and continuous decreased pulse-pressure perfusion has had no adverse effects in the short term. There has been no significant haemolysis and no device-related complications. The skull-mounted pedestal is unobtrusive and has healed well. CONCLUSIONS The initial success of this procedure raises the possibility of a new treatment for end-stage heart failure. In the longer term, its role will be determined by mechanical reliability.

Survival advantage of stentless aortic bioprostheses.

BACKGROUND Bioprostheses (BPs) are used to avoid anticoagulation after aortic valve replacement (AVR) in patients over 65 years of age. Stentless BPs offer established hemodynamic benefits. We sought to determine whether these advantages translate into improved survival. METHODS Between 1993 and 1997, follow-up data (for Food and Drug Administration submission) were collected prospectively for 160 consecutive, unselected hospital survivors who received the Freestyle valve (FS). Equivalent data were collected for 247 Carpentier-Edwards (CE) porcine xenograft patients. Detailed comparative statistical analysis was used to compare events and survival between the groups. Follow-up was 100% complete for the FS (5.2 years maximum; mean 3.2+/-1.0 years) group and 98% (7.2 years maximum; mean 3.8+/-2.0 years) for CE. RESULTS The groups were well matched in age (FS, 73+/-6 years; CE, 74+/-6 years), gender (FS, 58% male; CE, 62% male), ventricular function, and number of patients requiring coronary grafts (FS, 41%; CE, 37%). Actuarial survival at 5 years was 84% for FS versus 69% for CE (p = 0.023 Kaplan Meier, p = 0.009 Cox). Annual mortality rates were 3.6% for FS versus 7.1% for CE (p = 0.001). Thromboembolic rate was 0.8% per year for FS and 2.4% for CE (p = 0.024) without a difference in cardiac rhythm. Incidence of nonstructural dysfunction (paravalvular leak) was 0.2% for FS versus 1.3% for CE (p = 0.020). CONCLUSIONS By 5 years, the stentless valve patients had improved survival and reduced adverse events. Though differences in durability are yet to be proved, our findings support the use of stentless bioprostheses in this age group.

Mechanical Support in Dilated Cardiomyopathy: Signs of Early Left Ventricular Recovery

BACKGROUND Recent reports have documented left ventricular recovery in patients with dilated cardiomyopathy off-loaded long term with a left ventricular assist device. We sought to document the natural history of left ventricular recovery. METHODS We implanted the TCI left ventricular assist device without the intention to perform transplantation in 2 patients with dilated cardiomyopathy who had been rejected for transplantation. Both were in New York Heart Association functional class IV and had renal failure. One was a diabetic. We studied left ventricular function with detailed echocardiography at 4, 6, and 8 weeks postoperatively. RESULTS With the left ventricular assist device turned off, we observed a progressive increase in myocardial contractility beginning as early as 4 weeks after implantation and improving progressively. Histologic examination showed resolution of myocytolysis in both patients. CONCLUSIONS Left ventricular recovery begins earlier than was previously suspected. Mechanical bridge to myocardial recovery is a potential approach to therapy for such patients.

Valve replacement with a stentless bioprosthesis: Versatility of the porcine aortic root☆☆☆★

OBJECTIVE Stentless valves convey important hemodynamic benefits but are used selectively depending on aortic root structure. The Freestyle valve (Medtronic, Inc, Minneapolis, Minn) is a versatile device that can be implanted by different methods depending on operating conditions. We aimed to demonstrate that a stentless valve could be used in every patient without increased risk of morbidity or mortality. We documented the effects of this valve on clinical outcome and left ventricular mechanics. METHODS The Freestyle valve was implanted by the modified subcoronary method into 200 consecutive unselected patients who received a tissue valve in the aortic position and by root replacement in 2. Forty-three percent were older than 75 years. Forty percent underwent coronary bypass. Detailed clinical and echocardiographic follow-up (Food and Drug Administration protocol) was used out to 3 years. RESULTS Mean ischemic time was 43+/-6 minutes for isolated aortic valve replacement and 63+/-14 minutes with concomitant procedures. Thirty-day mortality was 6%, none of the deaths being valve related. Hemodynamic function improved progressively with falling valve gradients and increased effective orifice areas. Left ventricular mass fell within normal limits over 2 years, but at 3 years there was a non-valve-related upswing. No instances of valve thrombosis, hemolysis, or paravalvular leak were noted. Less than 5% had mild to moderate aortic regurgitation. CONCLUSIONS The Freestyle valve can be used in virtually every patient with aortic valve disease and provides superlative hemodynamic outcome. Hospital mortality and morbidity are similar to those reported for stented valves in an elderly population.

Medium-term determinants of left ventricular mass index after stentless aortic valve replacement

BACKGROUND This study aimed to investigate the risk factors for elevated left ventricular mass index 3 to 5 years after stentless aortic valve replacement, and to elucidate the underlying physiologic mechanisms. METHODS Eighty-nine patients (age, 76 +/- 6 years, 51 males) having a stentless porcine valve for aortic stenosis (n = 76) or regurgitation (n = 13) were prospectively studied by Doppler echocardiography 3 to 5 years after operation. Left ventricular systolic function, mass index, blood pressure, cardiac rhythm, and New York Heart Association function class were all determined. Stentless valve effective orifice area, mean pressure drop, and the presence and degree of aortic regurgitation were quantified. RESULTS The mean stentless aortic valve size was 24 +/- 2 mm. At follow-up time of 45 +/- 9 months, effective orifice area index was 1.2 +/- 0.35 cm2 x m(-2), and mean pressure drop was 5.7 +/- 3.8 mm Hg. Left ventricular mass index was 128 +/- 47 g x m(-2), and ejection fraction was 63% +/- 14%. Multivariant analysis showed a greater left ventricular mass index to be associated with nonsinus rhythm (versus sinus) (163 +/- 8 versus 131 +/- 7 g x m(-2)), greater pulse pressure (> 84 mm Hg) (161 +/- 7 versus 133 +/- 7 g x m(-2)), New York Heart Association class II or III (versus class I) (166 +/- 10 versus 128 +/- 5 g x m(-2)), and male sex (versus female) (160 +/- 7 versus 134 +/- 8 g x m(-2)), all p < 0.01. Mean pressure drop (> 8 mm Hg), effective orifice area index (< 1.0 cm2 x m(-2)), the presence of mild regurgitation of the stentless valve, or the type of previous valve disease were insignificant determinants of left ventricular mass index. CONCLUSIONS Three to five years after the implantation, stentless aortic valve hemodynamics remain excellent. Left ventricular hypertrophy caused by previous native aortic valve disease had largely regressed. However, patient-related factors, particularly systemic blood pressure, cardiac rhythm, and function, are significant causes of late residual left ventricular hypertrophy. Thus, continued medical care and earlier surgical intervention may further improve the outlook for these patients.

Left ventricular remodelling and improvement in Freestyle stentless valve haemodynamics

OBJECTIVE To assess how left ventricular (LV) hypertrophy, geometry and function change after stentless aortic valve replacement for aortic stenosis, and to elucidate the physiological mechanism of the improvement in stentless valve haemodynamics. METHODS 81 patients with aortic stenosis (age 75 +/- 6 years, 47 male) underwent aortic valve replacement (plus CABG in 33 patients) with a Freestyle stentless porcine valve (mean size 23 +/- 2 mm). They were prospectively investigated by Doppler echocardiography at 2 weeks, 3-6, 12, and 24 months after operation. Two hundred and forty-six echocardiograms were obtained and analysed. Aortic valve performance was assessed from its effective orifice area (EOA), the transvalvular increase in mean flow velocity (delta mV), the deceleration time of aortic flow velocity, and mean pressure drop (mPG). LV hypertrophy was assessed from LV mass index; LV geometry, from the ratio of wall thickness to the radius (T/R ratio) and LV function, from stroke volume index (LVSVI) and myocardial stroke work (SW). RESULTS By 2 years after operation, LV mass index had fallen from 162 +/- 64 to 109 +/- 36, g/m2, and T/R ratio from 0.61 +/- 0.25 to 0.43 +/- 0.10. LVSVI increased from 29.4 +/- 10 to 42 +/- 17, ml/m2, and myocardial SW from 3.1 +/- 1.6 to 5.2 +/- 2.2, mJ/cm3 (all P < 0.001 by ANOVA), while LV outflow tract diameter remained unchanged. At the same time, stentless valve EOA increased from 1.59 +/- 0.75 to 2.2 +/- 0.72, cm2, and delta mV (from 82 +/- 31 to 49 +/- 24, cm/s) and mPG (from 9.7 +/- 5.0 to 5.2 +/- 3.7 mmHg) both fell significantly (all P < 0.001 by ANOVA): as the deceleration time of aortic flow velocity increased from 153.6 +/- 64.1 to 202.7 +/- 37.6 ms (P < 0.001 by ANOVA). CONCLUSION After stentless aortic valve replacement, LV mass index and wall thickness both fall towards normal, and myocardial stroke work increases. These ventricular remodelling processes are accompanied by a more physiological flow jet at valve cusp level, which permits a greater stroke volume to be ejected with a smaller transvavular velocity increase, so that effective orifice area increases.

Mechanical bridge to recovery in fulminant myocarditis

A patient with acute fulminant lymphocytic myocarditis and cardiogenic shock was successfully treated by mechanical off loading of the left ventricle. A nonpulsatile left-heart bypass was undertaken with an implantable centrifugal blood pump. Careful weaning resulted in device removal on the seventh day. Left and right ventricular function is sustained at 7 months. Widespread application of this method depends on the availability of an inexpensive user friendly blood pump, appropriate weaning protocols and emerging strategies to promote sustainable myocardial recovery.

Pericardial and Porcine Stentless Aortic Valves: Are They Hemodynamically Different?

BACKGROUND We sought to compare the early hemodynamic performance of pericardial stentless aortic valves with that of well-established porcine stentless aortic prostheses. METHODS A total of 169 patients (97 men and 72 women, aged 73+/-6 years) undergoing aortic valve replacement received either a pericardial (Pericarbon, Sorin Biomedica, Saluggia, Italy; n = 89) or a porcine (Freestyle, Medtronic, n = 80) stentless aortic valve. Aortic valve hemodynamics and root dynamism were assessed by Doppler echocardiography at discharge and 12 months after implantation. RESULTS Clinical demographic data, valve size (24.0+/-1.9 vs 24.6+/-2.3 mm), and body surface area (1.85+/-0.19 vs 1.80+/-0.19 m2) did not differ between porcine and pericardial valves (both p > 0.05). The 1-year postoperative mean valve pressure gradient (4.2+/-2.6 vs 3.7+/-2.6 mm Hg), effective orifice area (2.2+/-0.8 vs 2.2+/-0.8 cm2), and left ventricular ejection fraction (62+/-13 vs 63+/-13, %) also did not differ (all p > 0.05). However, at discharge, systolic increase in aortic sinus diameter was significantly greater in pericardial valves than in porcine ones (7.7+/-5.7 vs 4.9%+/-4.2%, p < 0.01). Furthermore, pericardial valves had a greater slope of effective orifice area-systolic aortic flow relationship (0.89+/-0.07 vs 0.70+/-0.06, cm2/100 mL/s, p < 0.01). CONCLUSIONS Nonprosthetic thin-walled pericardial valves appear to offer better aortic root dynamism and more efficient hemodynamics than those of porcine valves immediately after implant. At 1-year follow-up, however, both types of stentless valves provide equally excellent hemodynamics. The clinical choice between the two will depend on their long-term durability.

Fifth-year hemodynamic performance of the prima stentless aortic valve

BACKGROUND The medium-term hemodynamic performance of stentless valves has not been widely reported, particularly in comparison with in vitro studies. Therefore, we have assessed prospectively the hemodynamics of the Edwards Prima valve in its fifth year after implantation in the aortic position, and compared the results with those at 1 month after implantation and also with in vitro data. METHODS Thirty-five patients (age, 77 +/- 6 years; 19 men) were prospectively studied by Doppler echocardiography at 1 month and 52 +/- 8 months after implantation of a Prima stentless valve. Valve hemodynamics were assessed by measuring the mean pressure gradient, mean valve resistance, and effective orifice area. Left ventricular systolic function was quantified by ejection fraction, the degree of hypertrophy by ventricular mass index, and the ratio of ventricular wall thickness to cavity radius as a measure of ventricular geometry. RESULTS With a mean valve size of 24.6 +/- 2.2 mm in the fifth year after implantation, the mean pressure gradient was 6.2 +/- 3.5 mm Hg, the mean valve resistance, 29 +/- 16 dyne x s(-1) x cm(-5)), and the effective orifice area was 2.05 +/- 0.50 cm2. Compared with 1 month after operation, there was a 47% decrease in mean valve resistance (p = 0.002) and a 39% increase in effective orifice area (p = 0.001). Furthermore, both effective orifice area and mean valve resistance in the fifth year did not differ from their in vitro counterparts, whereas the left ventricular ejection fraction (0.64 +/- 0.14), the left ventricular mass index (119 +/- 49 g/m2), and the ratio of ventricular wall thickness to cavity radius (0.44 +/- 0.13) were within the normal range. CONCLUSIONS This study suggests that the Prima valve is a reliable stentless aortic bioprosthesis. This is supported by a favorable medium-term clinical outcome, durable hemodynamic performance, and normal mean values of left ventricular ejection fraction and mass index in the fifth year after implantation.