Homograft replacement of the aortic valve and root as a functional unit.

Homograft replacement of the aortic valve has inherent advantages for the patient in terms of decreased incidence of thromboembolism, endocarditis, and anticoagulation-related complications. Limitations in its use stem from a significant incidence of postoperative aortic regurgitation, related to difficulty with consistent commissural and sinotubular geometry when inserted in the subcoronary position. To minimize this complication, we used a homograft as a functional unit in 71 patients between 1986 and May 1993, either as a root replacement (n = 58) or as an intraaortic inclusion cylinder (n = 13). There were 4 pulmonary and 67 aortic homografts. Mean age of the 16 female and 55 male patients was 42 +/- 19 years (range, 0.6 to 84 years). Thirty patients had predominantly aortic regurgitation, 19 aortic stenosis, 18 mixed aortic valve disease, and 4 primary aneurysmal disease. Eighteen (25.4%) had infective endocarditis. Thirty-five patients (49%) had a previous operation on the aortic valve. Hospital mortality was 14.1% (10/71), 0% for inclusion cylinders and 17.2% (10/58) for root replacements (p = not significant). Recent follow-up was obtained in all hospital survivors. Mean follow-up period was 35 months (range, 1 to 81 months). There were six late deaths, 1/13 for inclusion cylinders and 5/48 for root replacements. Actuarial survival at 5 years was 74.9% +/- 5.6%. Reoperation was required in 3 patients (all with root replacements), 1 for postoperative endocarditis, 1 for left coronary ostial obstruction, and 1 for late onset of aortic dilatation and regurgitation (pulmonary homograft used as a root replacement). Two patients currently have asymptomatic greater than 2/4 aortic regurgitation. Freedom from significant aortic regurgitation was 88% +/- 7% at 6-year follow-up. More consistent maintenance of the sinotubular and commissural geometry of the aortic homograft may be achieved with the root replacement or the inclusion cylinder techniques. This may reduce the incidence of postoperative aortic regurgitation and further benefit the patient by reducing the need for reoperation in the future.

Medium-term follow-up of pulmonary autograft replacement of aortic valves in children.

Pulmonary autograft replacement (PAG) of the aortic valve in children has been shown to be safe and effective with a low incidence of late valve dysfunction. Relief of all types of left ventricular outflow tract obstruction using the pulmonary root has been possible. Concern about the durability of the pulmonary root in the aortic position, and the potential for growth of the pulmonary autograft used either as a root replacement or intraaortic implant, has been questioned. Sixty-five consecutive patients, aged 1.8 to 21 years (mean 12 years) operated on between September 1986 and January 1993, 35 with an intra-aortic implant (IA) and 30 with root replacement (RR), were evaluated by clinical and serial echocardiographic studies (ECHO) up to 6.5 years post-operatively. The hospital mortality rate was 3.0% (70% CL 2.1-5.1%). Two patients required reoperation for PAG insufficiency (AI), one for technical malalignment necessitating replacement at 6 months, and one with progressive leaflet prolapse due to adherence of the valve leaflet to a ventricular septal defect (VSD) patch. Freedom from significant aortic regurgitation at 6-year follow-up was 100% for RR and 91 +/- 6% for IA, and freedom from all valve-related complications including reoperation was 92 +/- 5% at 6 years. Significant enlargement of the aortic annulus which parallels somatic growth has been measured by ECHO in 17 IA implants (P < 0.001) and 17 RR patients (P < 0.01) by 1 year, and in 10 IA (P = 0.007) and 6 RR (P < 0.05) by 2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary autograft replacement in children. The ideal solution?

Fifty-one children, aged 1.8 to 21 years (mean, 11.4) with aortic valve replacement using a pulmonary autograft are reviewed. Twenty-nine were intra-aortic implants and 22 were root replacements. There was one operative death, no late deaths, and two have required reoperation. Actuarial freedom from reoperation was 93% +/- 5.5 at 5.6 years. Freedom from progression of aortic insufficiency (AI) was 81% +/- 9 at 5.6 years in the intra-aortic implants and 86% +/- 10 in the root replacement. Enlargement of the pulmonary autograft was seen echocardiographically in both groups. This enlargement was consistent with somatic growth and not associated with progression of AI. Ten of 19 patients with aortic stenosis had an LV mass index suggestive of LV hypertrophy before operation. At 1 year, 18 of 25 had a normal LV mass index. Thirteen of 16 patients with AI had preoperative abnormal LV mass index. All but four returned to normal by 1 year. Low operative risk, excellent function, resolution of abnormal LV hemodynamics, and enlargement consistent with somatic growth suggest that the pulmonary autograft is the ideal replacement for the malfunctioning aortic valve.

Pulmonary autograft replacement of the aortic valve: an evolution of technique.

The use of the patient's pulmonary valve for replacement of the patient's diseased aortic valve was introduced and developed by Mr. Donald Ross. Its demonstrated durability, freedom from thromboembolism, and potential for growth has led to increased utilization of this technique. Modifications of the earlier techniques have led to a reproducible operation with low operative risk and excellent mid-term results.

Normal left ventricular function following pulmonary autograft replacement of the aortic valve in children.

To assess growth potential and hemodynamic sequelae of pulmonary autograft valves implanted into aortic outflow tracts of children, we reviewed our experience with 37 patients (2-21 years) from August 1986 to December 1990. Twenty patients had predominantly aortic stenosis (AS), and 17 had aortic insufficiency (AI). Operative mortality was 3%. Two technical failures required reoperation. Of survivors, six (18%) have moderate AI. Pre- and postoperative echocardiograms were reviewed. The AS group showed increased left ventricular (LV) cavity size by greater than 1-year follow-up, and decreased LV wall and interventricular septal thickness. In the AI group, wall and septal thickness increased by 10 days and LV cavity decreased by 10 days, 60 days, and greater than 1 year. Root replacements (n = 14) showed mean increases of 4.3 mm and 5.3 mm, respectively, in diameters of the aortic annulus and aortic sinuses at greater than 1 year. Intraaortic implants increased 3.1 mm (annulus) and 3.9 mm (sinuses) at greater than 1 year. The pulmonary autograft procedure is safe, and successful implantation normalizes LV dimensions and function rapidly. The autograft valve shows evidence of growth at greater than 1 year postoperative. The pulmonary autograft may be the ideal valve replacement in children.

Aortic valve and left ventricular outflow tract replacement using allograft and autograft valves: a preliminary report.

A comparison of allograft and autograft (pulmonary) replacement of the aortic valve has, to our knowledge, not been done in America. Fifty-seven patients (age range, 2 to 70 years; mean age, 30 years) underwent 59 operations for replacement of the aortic valve (20) or entire left ventricular outflow tract (39) using autograft (35) or allograft (24) valves. Many had undergone a previous operation (25) or had concomitant procedures (13). Postoperative mortality was 8.5% (5/59). Two deaths occurred in the allograft group and three in the more complex pulmonary autograft group. One late death occurred. One autograft was replaced with an allograft 7 months postoperatively for severe aortic regurgitation. There have been no episodes of either endocarditis or thromboembolism. Forty-nine of 51 survivors are in New York Heart Association class I. Preliminary results suggest that congenital or acquired disease of the left ventricular outflow tract and aortic valve can be safely and effectively treated with either allograft or autograft valve transplantation.

The superiority of cold oxygenated dilute blood cardioplegia.

It has been clearly shown, both in a laboratory model and in humans, that oxygenation of crystalloid cardioplegic solutions markedly enhances myocardial preservation. The addition of a small volume of red cells to a crystalloid perfusate improves capillary perfusion. Based on these results, we have changed our cardioplegic solution from cold crystalloid to cold oxygenated dilute blood. In the present study we retrospectively evaluate the results of 400 operative procedures to determine whether the addition of oxygenation and a small volume of blood to the cardioplegic solution enhances myocardial protection in the clinical setting. Two hundred consecutive patients who underwent operation with cardioplegic arrest using a cold crystalloid cardioplegic solution (group 1) were compared with a subsequent 200 patients who underwent operation with cold oxygenated dilute blood cardioplegia (group 2). Patients in group 2, who received cold oxygenated dilute blood cardioplegia, had a significantly reduced need for postoperative intraaortic balloon pump counterpulsation and for atrioventricular pacing. Also, patients in group 2 had a lower incidence of perioperative myocardial infarction and had improved early outcome. None of the 200 patients in group 2 had electrocardiographic evidence of perioperative infarction. We conclude that cold oxygenated dilute blood cardioplegia provides better preservation than does a nonoxygenated crystalloid solution during elective ischemic arrest, because a cold crystalloid solution is able to deliver oxygen and the red cells are able to enhance capillary perfusion.

Improved myocardial preservation with oxygenated cardioplegic solutions as reflected by on-line monitoring of intramyocardial pH during arrest.

To examine the relationship between intramyocardial pH during global ischemic arrest and subsequent functional and biochemical recovery, 40 canine hearts were subjected to 4 hours of arrest at 10 degrees C. Four groups, each containing 10 hearts, were differentiated by the oxygen concentration of a hyperkalemic crystalloid cardioplegic solution (CCS), which was infused every 20 minutes. In group 1 the CCS was equilibrated at 4 degrees C with nitrogen to remove oxygen. In group 2 the CCS was aerated at 4 degrees C. In group 3 the CCS was treated to achieve an oxygen tension (PO2) similar to group 2 but with a reduced nitrogen content to prevent bubble formation, which is theoretically possible during reperfusion ("myocardial bends"). In group 4 the CCS was fully oxygenated at 4 degrees C. The resulting PO2 of CCS measured at 10 degrees C was less than 20, 170, 170, and 750 mm Hg in groups 1, 2, 3, and 4, respectively. Left ventricular function (LVF) was assessed from function curves at constant mean aortic pressure and heart rate. Functional recovery, expressed as a percentage of prearrest LVF, was 38.1% +/- 10.7% in group 1 and 84.0% +/- 8.1% in group 4 (p less than 0.008). Functional recovery was 64.9% +/- 5.5% and 69.1% +/- 7.0% in groups 2 and 3, which had similar PO2. Differences in recovery between groups 2 and 3 and group 1 approached statistical significance (p less than 0.05, NS). The mean-integrated intramyocardial pH during arrest was higher (p less than 0.003) in group 4 (7.14 +/- 0.05) than in group 1 (6.84 +/- 0.06) or group 2 (6.86 +/- 0.07). The minimum intramyocardial pH during arrest was higher in group 4 than in any other group (p less than 0.002). Myocardial adenosine triphosphate concentration at the end of arrest, expressed as a percentage of its prearrest value, was highest in group 4 (75.9% +/- 8.1%) and lowest in group 1 (54.3% +/- 5.7%), a difference approaching statistical significance (p less than 0.05, NS). These data suggest that the measurement of intramyocardial pH is a useful on-line indicator of the adequacy of preservation during hypothermic arrest and that excess nitrogen in aerated CCS had little or no effect on recovery. The data confirm the hypothesis that oxygenation of CCS is associated with good myocardial preservation, which may be attributed to the provision of oxygen for the support of aerobic metabolism during arrest.

The effect of adding mannitol or albumin to a crystalloid cardioplegic solution: a prospective, randomized clinical study.

To determine if the myocardial protection afforded by a cold crystalloid potassium cardioplegic solution could be improved by the addition of either mannitol or albumin, a prospective clinical study was undertaken in which 58 patients undergoing elective aortocoronary bypass were randomized to one of three groups. Each group featured a different cardioplegic solution. The solutions were a standard potassium crystalloid solution, a solution containing mannitol sufficient to raise the osmolality by 20 to 30 mOsm, and a solution containing 5% albumin. Preoperative, intraoperative, and postoperative evaluation included serial measurements of ejection fraction, myocardial-specific isoenzyme, and hemodynamic indexes of performance. Electrocardiographic evaluation for perioperative myocardial infarction and the need for postoperative inotropic and mechanical support were also included. No differences were found among the groups. Therefore, although the use of mannitol or albumin has been shown to be beneficial in an experimental setting, superiority of either additive could not be demonstrated clinically.