Naoji Hanayama

Patient prosthesis mismatch is rare after aortic valve replacement: valve size may be irrelevant

BACKGROUND Although small valve size and patient-prosthesis mismatch are both considered to decrease long-term survival, little direct evidence exists to support this hypothesis. METHODS To assess the prevalence of patient-prosthesis mismatch and the influence of small valve size on survival, we prospectively studied 1,129 consecutive patients undergoing aortic valve replacement between 1990 and 2000. Mean and peak gradients and indexed effective orifice area were measured by transthoracic echocardiography postoperatively (3 months to 10 years). Abnormal postoperative gradients were defined as those patients with mean or peak gradient above the 90th percentile (mean gradient > or = 21 or peak gradient > or = 38 mm Hg). Patient-prosthesis mismatch was defined as those patients with indexed effective orifice area below the 10th percentile (< 0.60 cm2/m2). RESULTS A multivariable analysis identified internal diameter of the implanted valve as the only independent predictor of abnormal gradients postoperatively. However, there was no significant difference in actuarial survival between normal and abnormal gradient groups (7 years: 91.2% +/- 1.5% versus 95.0% +/- 2.2%; p = 0.48). Freedom from New York Heart Association class III or IV (7 years: 74.5% +/- 3.1% versus 74.6% +/- 6.2%; p = 0.66) and left ventricular mass index were not different between normal and abnormal gradient groups. Patients with and without patient-prosthesis mismatch were similar with respect to postoperative left ventricular mass index, 7-year survival (95.1% +/- 1.3% versus 94.7% +/- 3.0%; p = 0.54), and 7-year freedom from New York Heart Association class III or IV (79.3% +/- 6.6% versus 74.5% +/- 2.5%; p = 0.40). In patients with patient-prosthesis mismatch and abnormal gradients, the majority had prosthesis dysfunction owing to degeneration. CONCLUSIONS Severe patient-prosthesis mismatch is rare after aortic valve replacement. Patient-prosthesis mismatch, abnormal gradient, and the size of valve implanted do not influence left ventricular mass index or intermediate-term survival.

Are stentless valves hemodynamically superior to stented valves? A prospective randomized trial

BACKGROUND Although stentless aortic bioprostheses are believed to offer improved outcomes, hemodynamic benefits remain unsubstantiated. METHODS Fifty-three patients were randomized to receive the stented C-E pericardial valve (CE) and 46 patients the Toronto Stentless Porcine valve (SPV). Annuli were sized for the optimal insertion of both valve types, such that surgeons were required to commit to specific valve sizes before randomization. Echocardiographic measurements and functional status (Duke Activity Status Index) were assessed at 3 and 12 months postoperatively. RESULTS Although cardiopulmonary bypass times (CE: 118.6+/-36.3 minutes; SPV: 148.5+/-30.9 minutes; p = 0.0001) and aortic cross-clamp times (CE: 95.4+/-28.6 minutes; SPV: 123.6+/-24.1 minutes; p = 0.0001) were significantly prolonged in the SPV group, perioperative morbidity and mortality was similar between groups. Neither valve offered a superior internal diameter for any given annular diameter (mean decrease in left ventricular outflow tract diameter after valvular implantation: SPV: 3.4+/-1.11 mm versus CE: 3.7+/-1.33 mm; p = 0.25). Although labeled mean valve size was significantly larger in the SPV group, the actual mean valve size based on internal valvular diameter was no different between groups (CE: 21.9+/-2.0 mm; SPV: 22.3+/-2.0 mm; p = 0.286). Although effective orifice areas increased, and mean and peak transvalvular gradients decreased in both groups over time, no differences were demonstrated between groups at 12 months. Similarly, although significant regression of left ventricular mass was accomplished in both groups over time, no differences were demonstrated between groups. Finally, Duke Activity Status Index scores of functional status improved in both groups over time; however, no differences were noted between groups at 12 months postoperatively. CONCLUSIONS Although offering excellent outcomes, stentless valves did not demonstrate superior hemodynamic indices in comparison to stented valves up to 12 months after implantation.

Determinants of Incomplete Left Ventricular Mass Regression Following Aortic Valve Replacement for Aortic Stenosis

Abstract  Objective: Incomplete regression of left ventricular hypertrophy (Abn‐LVMI) following AVR for aortic stenosis (AS) may decrease long‐term survival. In this prospective study, we identified the predictors of Abn‐LVMI. Methods: Between 1990 and 2000, 529 patients undergoing AVR for AS had clinical and hemodynamic data collected prospectively. Preoperative and annual postoperative transthoracic echos were employed to assess left ventricular mass index (LVMI) and hemodynamics. Abn‐LVMI was defined as the 75th percentile of the lowest postoperative LVMI (>128 mg/m2, n = 133). All other patients were included in the normal regression group (N‐LVMI). Univariate and multivariable logistic regression analyses were used to determine the predictors of Abn‐LVMI. Results: Preoperative hypertension, diabetes, coronary disease, valve size, mean postoperative gradients, effective orifice area, and patient‐prosthesis mismatch (PPM, indexed EOA <0.60 cm2/m2) did not predict Abn‐LVMI. By logistic regression the most important positive predictor of Abn‐LVMI was the extent of preoperative LVMI, with an odds ratio of 37.5 (p < 0.0001). Survival (93.4 ± 1.8% vs 94.8 ± 2.3%, p = 0.90) and freedom from NYHA III–IV (75.0 ± 3.7% vs 76.6 ± 5.3%, p = 0.60) were similar for both groups at 7 years. Conclusions: Measures of valve hemodynamics were not important predictors of incomplete regression of hypertrophy. The extent of preoperative hypertrophy was the most important predictor, suggesting that earlier surgical intervention may reduce the extent of hypertrophy postoperatively. Furthermore, the significance of LV hypertrophy to long‐term survival must be reassessed, in the absence of scientific evidence.

Clinical Assessment of Prolonged Myocardial Preservation for Patients With a Severely Dilated Heart

BACKGROUND The purpose of this study was to compare the myocardial protective effect of histidine-tryptophan-potassium and glucose-insulin-potassium cardioplegic solutions in patients with a dilated heart (left ventricular diastolic diameter > 55 mm, left ventricular systolic diameter > 45 mm) associated with prolonged cross-clamp time (longer than 200 minutes). METHODS We selected 20 patients with dilated hearts due to severe aortic regurgitation. Glucose-insulin-potassium cardioplegia was used in 11 patients and histidine-tryptophan-potassium cardioplegia was used in 9 patients. RESULTS After operation, the cardiac index was significantly increased in the histidine-tryptophan-potassium group (p < 0.05). Postoperative percent fractional shortening was 13.4% +/- 3.1% in the glucose-insulin-potassium group and 23.6% +/- 2.6% in the histidine-tryptophan-potassium group (p < 0.05). Creatine kinase levels were significantly lower in the histidine-tryptophan-potassium group than that in the glucose-insulin-potassium group (p < 0.05). The incidence of ventricular arrhythmia (higher than Lowns grade 2) was lower in the histidine-tryptophan-potassium group. CONCLUSIONS These data support the superiority of the histidine-tryptophan-potassium method over the glucose-insulin-potassium method for protection of the dilated heart during prolonged ischemia in open heart operations.

Contemporary trends in aortic valve surgery: a single centre 10-year clinical experience.

Abstract  The purpose of this study is to present a comprehensive profile of the trends in aortic valve replacement at a single institution over the past decade. Prospectively collected data concerning 873 patients undergoing aortic valve replacement (AVR), with and without coronary artery bypass grafting (CABG), were analysed. The patients were divided into three time periods: period I, (1990 to 1993); period II, (1994 to 1996); and period III, (1997 to 2000). Actuarial survival of AVR patients with and without CABG at 7 years was 82.9 ± 2.4% and 79.1 ± 3.3% (p = 0.17), respectively. Actuarial survival at 7 years for stentless, mechanical, and stented valve patients were 89.5 ± 2.7%, 85.5 ± 2.8%, and 76.0 ± 3.2%, respectively. There was a significant difference in survival between the stentless and stented valve groups (p = 0.014). Age (63.8 ± 12.9 yrs, 66.2 ± 11.0 yrs, 67.9 ± 10.3 yrs; p = 0.01), the incidence of peripheral vascular disease (5.1%, 10.8%, 16.6%; p = 0.001), and the extent of coronary artery disease necessitating CABG (34.0%, 38.8%, 41.0%; p = 0.05) have increased significantly in the later time period. However, operative mortality has remained constant (4.7%, 4.8%, 4.5%; p = 0.9). Moreover, perioperative complications have decreased significantly (27.4%, 18.0, 16.0%; p = 0.001). Multivariate analysis identified more recent time period as independent protective factor for early mortality and morbidity (period I, RR 1.00; period II, RR 0.47; period III, RR 0.40).

Successful repair for a giant coronary artery aneurysm with coronary arteriovenous fistula complicated by both right- and left-sided infective endocarditis

We report a rare case of a 65-year-old woman who underwent an emergent lifesaving heart operation for an undiagnosed right coronary artery aneurysm with a coronary arteriovenous fistula complicated by active infective endocarditis, which affected the aortic valve, mitral valve, and coronary sinus. We performed direct closure of the coronary arteriovenous fistula, ligation of the right coronary artery aneurysm, double coronary artery bypass grafting, and double valvular replacement. Five years after the operation, she had no sign of congestive heart failure or infection, and was not receiving antibiotics.

Infectious endocarditis caused by Rhodococcus equi.

Rhodococcus equi is an unusual cause of infection. Furthermore, this infection also tends to be typically described in immunocompromised patients. This report describes a 25-year-old previously healthy man with infectious endocarditis that was found to have been caused by R equi complicated by a subarachnoid hemorrhage, subdural hematoma, and a superior mesenteric artery aneurysm. The patient was successfully treated with antibiotic therapy, followed by a resection of the superior mesenteric artery aneurysm and a repair of the mitral valve.

Should the Aortic Valve Homograft Be Recryopreserved

BACKGROUND The number of homograft donors is limited and the once-thawed homograft may be unsuitable for the recipient and obliged to be wasted. The purpose of this study was to investigate the possibility of recryopreserving and using the once-thawed homograft for another patient. METHODS Canine aortic valve leaflets were frozen to -80 degrees C by a programmed freezer, stored in liquid nitrogen, and thawed after 1 week. A subgroup of leaflets was left at 4 degrees C for 15 minutes, re-cryopreserved, and thawed after 1 week. Pathologic and flow cytometric evaluations were performed. RESULTS After thawing, by pathology, alignment of the fibers was acceptably maintained but the membrane and cytoplasm of the fibroblast were damaged. These findings were not significantly aggravated even after rethawing. By flow cytometry, fibroblast viability was 90.7%+/-1.7% immediately after thawing, 87.6%+/-1.0% after thawing for 15 minutes at 4 degrees C, 63.7%+/-2.7% during refreezing at 0 degrees C, and 39.4%+/-4.3% after rethawing. CONCLUSIONS From the standpoint of fibroblast viability, it is not possible to recryopreserve the once-cryopreserved and thawed aortic valve homograft.

Mid-term follow up results of Japanese heart transplant patients operated in UCLA Medical Center

UNLABELLED Japanese candidates have been accepted for heart transplantation by the UCLA Medical Center in the US since 1993 due to the lack of donors available from brain-dead patients. OBJECTIVES AND METHODS We monitored to patients who underwent such heart transplantation and have been seen at the out-patient clinic at Tokyo Womens Medical University following transplantation. Pre-operative diagnosis was dilated cardiomyopathy in all patients. One patient underwent Novacor implantation as a bridge to heart transplant. All patients underwent cardiac echocardiography and cardiac catheterization including intraluminal echography. RESULTS All patients survived with an actuarial survival curve of 100% at 1 year, 100% at 3 years and 87% at 5 years in 4.15 years of average follow-up. Two patients died due to liver dysfunction and cerebral emboli. The postoperative functional status of patients was New York Heart Association classification I in 8 (100%). Immunosuppressive therapies included triple drug therapy using either cyclosporin or tacrolimus. The incidence of acute rejection (/pt) exceeding grade 3 was 4% within three months, 3.5% in 3-6 months, and no significant rejection episode more than 6 months after transplantation. Posttransplantation coronary artery disease was seen in 2 patients, but no progression was seen after diltiazem therapy. CONCLUSION Our postoperative follow-up after cardiac transplantation appears to be satisfactory.

Mechanisms of Exercise Response in Denervated Heart After Transplant

Mechanisms through which the denervated heart responds to supine exercise were assessed in various ways in seven cardiac transplant recipients, 1–37 months after surgery. The results were compared with those in 15 normal subjects. The heart rate at rest and after exercise in transplant patients was 30% higher than normal (P < 0.01). Although cardiac output at rest was similar in both groups, early in exercise the means by which cardiac output increased in the transplant patients differed from normal. In the transplant recipients during the early stage of exercise, the blood norepinephrine level was significantly elevated, and the percent fraction shortening and velocity of circumferential fiber shortening (Vcf) was also higher than in normal subjects with an approximately similar heart rate. The level of atrial natrium diuretic peptide was also significantly increased during exercise by augmented preload (P < 0.01). These results support the concept that in the transplanted heart, there are increases in cardiac output via mechanisms different from those in normal hearts.