Partial left ventriculectomy: which patients can be expected to benefit?

Background. Although some patients with end-stage heart disease will benefit from a partial left ventriculectomy, no criteria have been found for identifying this group preoperatively. Our experience with partial left ventriculectomy at two institutions—the Texas Heart Institute in Houston, TX, USA, and Dedinje Cardiovascular Institute in Belgrade, Yugoslavia—showed a higher survival rate and better postoperative myocardial function in the Yugoslavian patients.

Methods. We reviewed data from 42 patients (21 at each center) who had idiopathic cardiomyopathy, a left ventricular end-diastolic dimension of more than 70 mm, wall thickness of 1 cm or greater, and New York Heart Association class III or IV symptoms. The only significant difference in preoperative status between the two groups was duration of symptoms. Histologic specimens, blinded as to origin, were graded with regard to myocyte hypertrophy, cytoplasmic vacuolation, and fibrosis. Computer-assisted myocyte and nuclear morphometry was also performed.

Results. Immediately postoperatively, there were no significant intergroup differences in the reduction in cardiac dimension or in corrections of mitral regurgitation. During 6-month follow-up, however, the Texas Heart Institute patients had a lower cardiac index (1.8 versus 3.0 L·min⁻¹·m⁻²; p = 0.001) and left ventricular ejection fraction (24% versus 34%; p = 0.006) than the Dedinje Cardiovascular Institute patients. The Texas Heart Institute patients differed from the Dedinje Cardiovascular Institute patients in the degree of severe or moderate changes in myocyte hypertrophy (90% versus 29%; p = 0.0003) and fibrosis (71% versus 29%; p = 0.006), as well as in the measurements of median myocyte diameter (35 ± 7 μm versus 27 ± 4 μm; p = 0.0002) and median nuclear size (15 ± 4 μm versus 12 ± 2 μm; p = 0.0029).

Conclusions. In the Texas Heart Institute patients, the significant intergroup difference in clinical outcome may have been related to increased myocyte hypertrophy and fibrosis. Further studies should be performed to determine the usefulness of these criteria in selecting patients for partial left ventriculectomy.     

Preliminary experience with the St. Jude Medical Regent mechanical heart valve in the aortic position: early in vivo hemodynamic results

Background. The St. Jude Medical Regent is a new generation mechanical aortic valve.

Methods. Between March 2000 and July 2001, this valve was implanted in the aortic position in 40 patients (21 men; mean age 59.1 ± 9.0 years). Preoperatively, 24 patients (60%) were in New York Heart Association functional class III or IV. Eighteen patients (45%) underwent associated procedures. Mean valve size was 21.4 ± 2.4 mm. The mean duration of follow-up was 8.5 ± 4.5 months (range, 1 to 16 months).

Results. There were no operative deaths. Early complications included one reoperation for bleeding and one transient low output syndrome. Valve replacement was followed by a significant reduction in mean and peak transaortic gradients over time (p < 0.001) and analysis of variance failed to demonstrate statistical differences between valve size over time (p = not significant). A significant reduction in left ventricular hypertrophy occurred over time (p = 0.01) in all valve sizes (p = not significant between groups): baseline left ventricular mass index was 194 g/cm²; it reduced by 22 g/cm² (p = 0.006) at discharge. Left ventricular mass index decreased from 172 ± 55 g/cm² to 156 ± 44 g/cm² (p = 0.03) from discharge to 2 months. Further reductions were not significant. Relative wall thickness decreased from 0.57 ± 0.13 preoperatively to 0.42 ± 0.06 at discharge (p = 0.001), and again at 2 months (−0.2; p = not significant), and at 1 year (−0.02; p = not significant).

Conclusions. The early experience with the St. Jude Medical Regent valve has been satisfactory.     

Early experience with partial left ventriculectomy in the Asia-Pacific region

Background. We report our early experience with partial left ventriculectomy done by a group of cardiac surgeons in the Asia-Pacific region.

Methods. Partial left ventriculectomy was done in 48 patients (mean age, 43 years) with advanced symptomatic cardiomyopathy. The origin of cardiomyopathy was idiopathic in 30 patients, valvular in 10, ischemic in 3, peripartum in 3, sarcoidosis in 1, and viral myocarditis in 1. Procedures performed on the mitral valve were repair with Alfieri method in 8 patients, ring annuloplasty in 2, and replacement in 25.

Results. Seventy-seven percent of patients required myocardial support for weaning from cardiopulmonary bypass, and the overall in-hospital mortality rate was 27%. Mean follow up was 6.5 months (range, 1 to 18 months), and patient survival at 1, 3, and 6 months after discharge was 91%, 88%, and 84%, respectively. Sixty-five percent of survivors with idiopathic and valvular disease achieved significant and sustained improvement in ventricular contractility and symptoms, but there were no clear symptomatic benefits from partial left ventriculectomy in patients with cardiomyopathy from other causes. Most cases of late recurrence of heart failure symptoms (90%) appeared to be related to the development of progressive mitral incompetence.

Conclusions. After partial left ventriculectomy left ventricular function improved in patients with idiopathic and valve related cardiomyopathies. Late deterioration was related to the development of significant mitral valve incompetence postoperatively, hence definitive mitral valve repair or replacement at the time of the partial left ventriculectomy procedure is advised.     

Comparison of clinical results for unilateral and bilateral thoracoscopic lung volume reduction

Background. It is widely believed that bilateral thoracoscopic lung volume reduction (BTLVR) yields superior results when compared with unilateral thoracoscopic lung volume reduction (UTLVR) with regard to spirometry, functional capacity, oxygenation and quality of life results.

Methods. To address these issues, we compared the results of patients undergoing UTLVR (N = 338 patients) and BTLVR (N = 344 patients) from 1993 to 1998 at five institutions. Follow-up data were available on 671 patients (98.4%) between 6 and 12 months after surgery, and a patient self-assessment was obtained at a mean of 24 months.

Results. It was found that BTLVR provides superior improvement in measured postoperative percent change in FEV₁ (L) (UTLVR 23.3% ± 55.3 vs BTLVR 33% ± 41, p = 0.04), FVC(L) (10.5% ± 31.6 vs 20.3% ± 34.3, p = 0.002) and RV(L) (−13% ± −22 vs −22% ± 17.9, p = 0.015). BTLVR also provides a slight improvement over UTLVR in patient’s perception regarding improved quality of life (UTLVR 79% vs BTLVR 88%, p = 0.03) and dyspnea relief (71% vs 61%, p = 0.03). There was no difference in mean changes in Po₂ (mm Hg) (UTLV 4.5 ± 12.3 vs BTLVR 4.9 ± 13.3, p = NS), 6-minute walk (UTLVR 26% ± 66.1 vs BTLVR 31% ± 59.6, p = NS) or decreased oxygen utilization (UTLVR 78% vs BTLVR 74%, p = NS).

Conclusions. These data suggest that both UTLVR and BTLVR yield significant improvement, but the results of BTLVR seem to be superior with regard to spirometry, lung volumes, and quality of life.     

Left ventricular volume reduction without ventriculectomy

Partial left ventriculectomy (the Batista procedure) to achieve left ventricular volume reduction (LVVR) has been advocated as an alternative to cardiac transplantation in patients with end-stage dilated left ventricles. Here, we describe a new technique of LVVR that uses realignment of the papillary muscles, thus avoiding ventriculectomy, and report preliminary results. Eight patients (all male, mean age 49.3 [range 38 to 70] years) underwent LVVR between October 1998 and March 2000 as an adjunct to surgical coronary revascularization. Five were assessed with echocardiography and cardiopulmonary exercise testing before and after (mean follow-up time 267 [range 94 to 416] days) the operation. LVVR significantly improved left ventricular end-diastolic volume (254 ± 32 to 218 ± 36 mL, p = 0.03), left ventricular ejection fraction (20.14% ± 1.36% to 31.28% ± 2.32%, p = 0.007), and exercise duration (from 394 ± 88 to 611 ± 79 seconds, p = 0.03). A nonsignificant improvement in maximal oxygen consumption was also observed. This technique of LVVR is relatively simple to perform and is accomplished through a small apical cardiotomy. Preliminary results show an encouraging functional improvement following surgery. Future controlled studies are required to assess this novel technique further.     

The Edwards Prima stentless valve: hemodynamic performance at one year

Background. The Edwards Prima stentless valve (EPSV) is a porcine aortic root cylinder with resected coronary ostia, fixed in glutaraldehyde at low pressure. The purpose of this study was to evaluate the hemodynamic performance of the EPSV 1 year after aortic valve replacement.

Methods. From December 1994 to February 1996, 29 patients underwent aortic valve replacement with EPSV used in the subcoronary position (group 1, n = 23) or as a root replacement (group 2, n = 6). Hemodynamic performance of EPSV was assessed by two-dimensional Doppler echocardiography at 1 week, 6 months, and 1 year by calculating peak transprosthetic velocity, peak and mean gradients, effective orifice area, degree of aortic regurgitation, and regression of left ventricular hypertrophy.

Results. There were no operative deaths. One patient in group 2 died after 3 months at reoperation for endocarditis. In group 1 early mean gradient (25 ± 5 mm Hg for 23 mm and 19 ± 5 mm Hg for 25 mm) decreased at 6 months and 1 year in the 23-mm size (17 ± 7 mm Hg and 15 ± 4 mm Hg, p < 0.01) and at 1 year in the 25-mm size (14 ± 4 mm Hg, p = 0.03) without modifications of the effective orifice area in both sizes. A significant reduction in left ventricular hypertrophy occurred at 6 months and 1 year in both sizes. In group 2 lower early gradients were recorded with subsequent improvement at follow-up; reduction in left ventricular hypertrophy occurred as well.

Conclusions. The EPSV used in the subcoronary position has shown high early gradients, which partially regressed at 6 months, with further improvement at 1 year. Gradients are attributed to inward folding of the Dacron cloth at the right coronary ostium, being more evident in patients with aortic stenosis without dilatation of the aortic root and coronary ostia close to the annulus. In such patients a better early hemodynamic result can be obtained by using the EPSV as a root replacement.     

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 ≥ 21 or peak gradient ≥ 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.     

Valvular heart operation in patients with previous mediastinal radiation therapy

Background. The outcome of valvular heart operations in patients with previous mediastinal radiation therapy was studied.

Methods. This is a single center retrospective study of 60 patients (37 females, 23 males) with a mean age of 62 ± 15 years (28 to 88 years old) operated on from January 1976 to December 1998. Valvular heart operations performed included aortic valve replacements (n = 26), mitral valve procedures (n = 16), tricuspid valve procedures (n = 6), and multiple valve procedures (n = 12). A total of 264 clinical, hemodynamic, electrocardiographic and echocardiographic variables were analyzed.

Results. Total follow-up was 199 patient-years with a mean of 3.3 ± 3.1 years and a range of 0 to 12.4 years old. Early mortality was 7 patients (12%). Early mortality in patients with constrictive pericarditis was 40% (4 of 10) compared with 6% (3 of 50) in patients without constrictive pericarditis. By univariate analysis, early mortality was associated with constrictive pericarditis (p = 0.011), reduced preoperative ejection fraction (p = 0.015), and longer cardiopulmonary bypass times (p = 0.037). A total of 14 patients (23%) required permanent pacemaker placement before (n = 7), during (n = 1), or early (n = 6) after valvular heart operations. There were 19 late deaths (malignancies, 7; heart failures, 5; other cardiac, 4; and other noncardiac, 3). Overall survival and freedom from late cardiac death and cardiac reoperation at 5 years for hospital survivors were 66% ± 8%, 82% ± 7%, and 93% ± 4%, respectively. By univariate analysis, late cardiac death was associated with low ejection fraction (p = 0.002), New York Heart Association (NYHA) functional class IV (p = 0.004), preoperative congestive heart failure (p = 0.02), and preoperative atrial fibrillation (p = 0.038). Eighty-five percent of the discharged patients were in NYHA functional class I or II at follow-up.

Conclusions. Early results of valve replacement after mediastinal radiation therapy were good except in the presence of constrictive pericarditis. Long-term outcome was limited by malignancy and heart failure. Early surgical intervention is recommended before the development of risk factors for late death, namely, severe symptoms, left ventricular dysfunction, and atrial fibrillation.     

Ventricular remodeling after cardiomyoplasty in heart failure sheep: passive and dynamic effects

Background. Recent reports claim that cardiomyoplasty (CMP) has a girdling effect on the left ventricle, to prevent dilatation and functional deterioration, but the mechanism of its long-term effects on the native heart is not known. We compared the relative role of CMP’s active squeezing and passive girdling in chronically failing hearts.

Methods. After induction of stable heart failure (left ventricular ejection FRACTION = 27% ± 7%) by staged coronary microembolization, CMP was performed in 11 of 18 sheep. After 8 weeks pacing training of the latissimus dorsi muscle (LDM), cardiac assist was begun with 1:2 synchronous bursts in 6 sheep (d-CMP, N = 6), and the LDM in the passive group (p-CMP, N = 5) remained unstimulated. Four (base line) and 30 weeks after induction of heart failure, the pressure-volume relationship was derived.

Results. After 30 weeks in d-CMP the slope (E_max) of the end-systolic pressure-volume relationship increased by 66% ± 55% (p < 0.05) and external work efficiency by 48% ± 41% (p < 0.01). In the passive CMP and control groups, slope and external work efficiency were unchanged. Conversely, left ventricular end-diastolic volume decreased (−14% ± 12%, p < 0.05) in the dynamic CMP group compared with a static course in the passive CMP group (3% ± 10%, p > 0.05) and an increase (18% ± 15%, p < 0.05) in controls.

Conclusions. Dynamic CMP improved native heart’s contractility and external work efficiency. In addition, whereas passive CMP has simply a girdling effect, dynamic CMP also induces reverse left ventricular chamber remodeling.     

Comparison of outcomes between living donor and cadaveric lung transplantation in children

Background. Long-term survival in lung transplant is limited by bronchiolitis obliterans (BOS). We compared outcomes in pediatric living donor bilateral lobar (LL) vs cadaveric lung transplant (CL).

Methods. Children were studied who had LL or CL with at least 1 year follow-up. Data collected included acute rejection episodes, pulmonary function tests (PFT), BOS, and survival. Mean age was 13.36 ± 3.16 years in LL and 12.00 ± 4.19 years in CL patients (p = 0.37, ns).

Results. There was no difference in rejection (p = 0.41, ns). CL had rejection earlier (2.48 ± 3.84 months) than LL (13.60 ± 10.74 months; p = 0.02). There was no difference in 12 month PFT. But at 24 months, LL had greater forced expiratory volume in 1 second (FEV₁) (p = 0.001) and FEF_25–75% (p = 0.01) than CL. BOS was found in 0/14 LL vs 9/11 (82%) CL after 1 year (p = 0.04). After 2 years, 0/8 LL and 6/7 (86%) CL had BOS (p < 0.05). LL had 85% survival vs 79% for CL at 12 months. At 24 months, LL survival was 77% vs 67% for CL.

Conclusions. Pediatric LL had less BOS and better pulmonary function than CL. As BOS is a determinant of long-term outcome, we believe LL is the preferred lung transplant method for children.     

Hemodynamic changes with right lateral decubitus body positioning in the tilted porcine heart

Background. In beating-heart coronary surgical procedures, exposure of posterior vessels through sternotomy causes cardiac function to deteriorate. We hypothesized that turning the subject to the right lateral decubitus position before cardiac retraction improves exposure of posterior vessels and preserves cardiac pump function on displacement.

Methods. Eight 80-kg open-chest pigs were instrumented with catheter-tip manometers. After a stepwise 60-degree turn to the right lateral decubitus position of the body, the heart was retracted anteriorly to 90 degrees with a suction stabilizer.

Results. Right lateral body positioning caused an approximately 45-degree right deviation of the apex, thereby exposing the left atrial groove. Stroke volume, mean arterial pressure, right atrial pressure, and right ventricular end-diastolic pressure increased to 106% ± 5% (mean ± standard error of the mean, p = 0.31), 106% ± 3% (p = 0.01), 129% ± 8% (p = 0.001), and 171% ± 14% (p = 0.002), respectively, compared with control values. In contrast, left atrial pressure decreased to 73% ± 6% (p = 0.007), whereas left ventricular preload remained unchanged (110% ± 8%, p = 0.26). Additional anterior displacement to 90 degrees fully exposed the posterior vessels, and stroke volume decreased to 90% ± 3% (p = 0.01) and mean arterial pressure to 93% ± 5% (p = 0.07) at the expense of further increased right ventricular preload (256% ± 28%, p < 0.001).

Conclusions. By placing the subject in the right lateral decubitus position, exposure through sternotomy of posterior vessels in the beating porcine heart was facilitated while mean arterial pressure was maintained.     

Modified Norwood operation for hypoplastic left heart syndrome

Background. We examined early results in infants with hypoplastic left heart syndrome undergoing the Norwood operation with perioperative use of inhaled nitric oxide and application of extracorporeal membrane oxygenation.

Methods. Medical records were reviewed retrospectively.

Results. Between April 1997 and March 2001, 50 infants underwent a modified Norwood operation for hypoplastic left heart syndrome. Mean age at operation was 7.5 ± 5.7 days, and mean weight was 3.1 ± 0.5 kg. Five infants had a delayed operation because of sepsis. The mean diameter of the ascending aorta by echocardiography was 3.6 ± 1.8 mm. Ductal cannulation was used to establish cardiopulmonary bypass in all patients. Mean circulatory arrest time was 39.4 ± 4.8 minutes. The size of the pulmonary-systemic shunt was 3.0 mm in 6 infants, 3.5 mm in 37, and 4.0 mm in 7. Infants with persistent hypoxia (partial pressure of oxygen < 30 mm Hg) received nitric oxide after they were weaned from cardiopulmonary bypass. Extracorporeal membrane oxygenation was initiated in 8 infants in the pediatric intensive care unit primarily for low cardiac output and in 8 in the operating room because of the inability to separate them from cardiopulmonary bypass. The 30-day mortality rate was 22% (11 of 50 patients), and the hospital mortality rate was 32% (16 of 50 patients). Mean follow-up was 17 months. Ten patients (20%) underwent stage-two repair, with one operative death. One survivor had a Fontan procedure, and 2 underwent heart transplantation, with one death.

Conclusions. Early application of extracorporeal membrane oxygenation for hemodynamic instability and selective use of nitric oxide for persistent hypoxia in the immediate postoperative period may improve survival of patients with hypoplastic left heart syndrome. Renal failure requiring hemofiltration during extracorporeal membrane oxygenation (p < 0.05) and cardiopulmonary arrest in the pediatric intensive care unit (p < 0.05) were predictors of hospital mortality.     

Recurrence of aortic insufficiency after aortic root remodeling with valve preservation

Background. Aortic root remodeling (ARR) has recently been proposed for patients with aortic aneurysms and valve insufficiency (AI). To define factors associated with a favorable functional outcome, a review of the mid-term results with ARR was undertaken.

Methods. Between March 1994 and October 1997, 17 consecutive patients (11 men, 6 women), aged 57 ± 11 years (range 35–71), had elective ARR for aortic aneurysm with or without annuloaortic ectasia (13), sinus of Valsalva aneurysm (3), or chronic aortic dissection (1). Moderate or severe AI was present in 11 patients (65%). Preoperative aortic root diameter was 58 ± 5 mm (range 51–70). ARR involved replacement of all three aortic sinuses and coronary button reimplantation, using grafts with a mean diameter of 28 ± 2 mm (range 24–30).

Results. There was one early death (6%) due to multiple organ failure. Survivors were followed for 16 ± 12 months (range 1–44). Actuarial 3-year survival was 94% ± 6%. Discharge echocardiogram showed a decrease in AI in all patients: AI was absent in 11 (69%) and mild in 5 (31%). Recurrence of moderate or severe AI after a mean of 16 ± 9 months (range 9–28) was noted in 6 patients (37%), 3 of whom had no AI at discharge. Five of 6 patients required aortic valve replacement. Comparison of demographic and operative variables showed that severe preoperative AI (67% vs 20%, p = 0.06), annuloaortic ectasia (100% vs 20%, p = 0.002), and cystic medial necrosis (100% vs 20%, p = 0.002) were significantly more prevalent in patients developing severe AI at follow-up. The 10 patients (63%) with absent AI showed durable competence of the valve and relief from symptoms at follow-up.

Conclusions. Despite early restoration of valve competence, AI may recur and progress after ARR at medium-term follow-up in a proportion of patients. The severity of preoperative AI and the nature of aortic root disease may negatively influence the durability of repair. Continued observation of results with ARR appears mandatory to identify the appropriate surgical candidates.     

Valved homograft replacement of aneurysmal pulmonary arteries for severely symptomatic absent pulmonary valve syndrome

Background. Patients with absent pulmonary valve syndrome (APVS) with respiratory distress (RD) have previously had a high mortality. In 1990 we adopted a strategy of primary repair including total replacement of the aneurysmal central pulmonary arteries (PAs) for patients with RD.

Methods. Retrospective review was made of 54 consecutive patients with APVS between 1960 and 1998. Median age and weight were 4 months and 4.8 kg. RD was present in 23 patients (10 neonates, 16 required ventilation). Fifteen patients had repair with homograft replacement of the PAs and VSD closure (group 1). Twenty-seven patients had transannular patch with VSD closure with PA-plasty (group 2, n = 21) or without PA plasty (group 3, n = 6). Twelve had miscellaneous procedures (group 4); in 6 the VSD was left open.

Results. Operative, 1-, 5-, and 10-year survivals were 83%, 80%, 78%, and 78%, respectively. Risk factors for operative mortality in multivariate analysis were RD (p = 0.04), neonates (p = 0.02), weight less than 3 kg (p = 0.02), open VSD (p = 0.02) and surgery before 1990 (p = 0.04). Since 1990 operative mortality has decreased to 11% (p = 0.04). RD was the only time-related predictor of survival in multivariate analysis (p = 0.004). In patients with RD, survival with homograft was 73% versus 41% with other techniques (p = 0.2). Mean follow-up was 72 ± 50 months. There were no significant differences in freedom from reintervention rates among the surgical groups (p = 0.08).

Conclusions. Aggressive homograft replacement of the central pulmonary arteries has been associated with improved survival in patients with APVS especially in neonates with severe RD.     

Predicting Feasibility of Biventricular Repair of Right-Dominant Unbalanced Atrioventricular Canal

Background. In right-dominant unbalanced atrioventricular (AV) canal, there are no criteria to judge adequacy of the left ventricle for biventricular repair. The purpose of this study was to test the hypothesis that right ventricular volume overload in this condition results in right-to-left septal bowing and contributes to the appearance of a small left ventricle.

Methods. Five consecutive neonates and young infants (age range, 23 days to 5 months; median age, 3 months) with right-dominant unbalanced complete AV canal underwent biventricular repair. Preoperative and postoperative echocardiographic measurements of left (LV) and right ventricular size and AV valve component size were made. Potential LV volume was assessed preoperatively using a theoretic model that assumed a normalization of septal bowing.

Results. There was no perioperative mortality; 1 patient died 71 days postoperatively of problems related to the left AV valve. Preoperatively, all patients had severe LV hypoplasia, with a mean end-diastolic indexed true LV volume of 14.8 ± 9.1 mL/m², indexed potential LV volume of 32.0 ± 18.8 mL/m², left AV valve to total AV valve ratio of 0.30 ± 0.06, and LV to right ventricular long-dimension ratio of 0.65 ± 0.1. Postoperatively, all patients had indexed true LV volumes greater than 30 mL/m² (mean volume, 35.6 ± 3.9 mL/m²), and the left AV valve to total AV valve ratio and the LV to right ventricular long-dimension ratio increased to 0.42 ± 0.03 and 0.88 ± 0.11, respectively. Both preoperative potential and true LV volumes correlated well with postoperative true LV volumes: r = 0.90 (p = 0.040) and r = 0.93 (p = 0.023), respectively. Increases in LV length and left AV annulus size indicated contributions of volume loading and surgical patching to the right of the ventricular crest to the increase in LV size.

Conclusions. In our small series, preoperative indexed potential LV volume of 15 mL/m² or greater (present in all patients) allowed biventricular repair of right-dominant unbalanced AV canal. Any previous criteria for LV hypoplasia in this condition need to be reconsidered. This study also has implications for other right-sided volume-loaded lesions in which the left ventricle initially is judged to be hypoplastic but in which biventricular repair may be feasible.     

Biological and clinical assessment of a new bisphosphonate, (chloro-4 phenyl)thiomethylene bisphosphonate, in the treatment of Paget's disease of bone

Several Biophosphonates have been used as therapeutic agents for Paget's bone disease. (Chloro-4 phenyl)thiomethylene-bisphosphonate (CIPsMBP) has recently been shown to have significant antiosteoclastic activity while an affect of CIPsMBP on mineralization was only observed at high doses. We tested this drug for 6 months in 23 pagetic patients distributed in three groups. Gr 1 (n = 5) receiving 200 mg/day showed a decrease of serum alkaline phosphatase (SAP) to 42 ± 4% (p < 0.01) of initial value (100%) while hydroxyprolinuria/creatinuria ratio (OH/Cr) dropped to 69 ± 8% of baseline. In 4 patients receiving 400 mg/day, SAP improved to 48 ± 9% of initial value (p < 0.01) and OH/Cr to 40 ± 3% (p < 0.01). In the last group (n = 14) receiving 200 mg/day for 3 months, and 400 mg/day thereafter up to the 6th month SAP decreased to 53 ± 4% and OH/Cr to 62 ± 6% of initial value (p < 0.01).

Clinical improvement was significant from the first month of treatment. No resistance (mean decrease of SAP lower than 30%) was recorded and no radiological or clinical evidence of mineralization defect appeared. The clinical and biological tolerance was excellent throughout the study.     

PET Scan Predicts Recovery of Left Ventricular Function After Coronary Artery Bypass Operation

Background. Viable but hypocontractile myocardium can show functional improvement after revascularization (hibernation). It is sometimes difficult, however, to predict viability and recovery in patients with severe left ventricular function. This study sought to identify possible predictive factors of recovery of cardiac function after revascularization in patients with three-vessel disease.

Methods. Positron emission tomography (fluoro-18-deoxyglucose uptake for metabolism; nitrogen 13–labeled ammonia for flow) and equilibrium-gated nuclear angiography (for the global ejection fraction) were performed in 59 patients with three-vessel disease before and after undergoing coronary artery bypass grafting. The positron emission tomographic data were expressed as match normal (flow and metabolism normal), mismatch (low flow, high metabolism), match viable (moderate decrease in flow and metabolism), and match necrosis (low flow and metabolism).

Results. Stepwise logistic regression analysis showed that only mismatch regions played a significant role in predicting postoperative improvement in function (p = 0.019). There were 1.7 ± 1.5 mismatch regions in 31 patients who showed an improvement in their ejection fraction (0.47 ± 0.14 versus 0.58 ± 0.11; mean ± standard deviation) versus 0.8 ± 1.0 mismatch regions (p = 0.017) in patients who did not show recovery. There was more pronounced functional improvement with increasing numbers of mismatch regions, and patients with at least one mismatch region had a high likelihood of recovery (p < 0.001). In patients with a very low preoperative ejection fraction and two or more mismatch regions, there was early significant recovery (0.27 ± 0.08 versus 0.46 ± 0.06; p = 0.009).

Conclusions. At least one mismatch region must be present for there to be a postoperative functional benefit. When a low left ventricular ejection fraction is associated with mismatch, early recovery is substantial.     

Long-term survival after thoracoscopic lung volume reduction: a multiinstitutional review

Background. It has been suggested that bilateral thoracoscopic lung volume reduction (BTLVR) yields significantly better long-term survival than unilateral thoracoscopic lung volume reduction (UTLVR).

Methods. All perioperative data were collected at the time of the procedure. Follow-up data were obtained during office visits or by telephone.

Results. A total of 673 patients underwent thoracoscopic LVR: 343 had either simultaneous or staged BTLVR and 330, UTLVR. As of July 1998, follow-up was available on 667 (99%) of the 673 patients with a mean follow-up of 24.3 months. The patients in the BTLVR group were significantly younger (62.6 ± 8.0 years versus 65.4 ± 8.1 years; p < 0.0001), had a higher preoperative arterial oxygen tension (69.7 ± 12 mm Hg versus 65.3 ± 11 mm Hg; p < 0.0001), and had a superior preoperative 6-minute walk performance (279.9 ± 93.6 m [933 ± 312 feet] versus 244.5 ± 101.4 m [815 ± 338 feet] p < 0.0001). There was no difference in the operative mortality rate between the two groups (UTLVR, 5.1%, and BTLVR, 7%). Actuarial survival rates for the UTLVR group at 1 year, 2 years, and 3 years were 86%, 75%, and 69%, respectively versus 90%, 81%, and 74%, respectively, for the BTLVR group (p = not significant).

Conclusions. Contrary to previous reports, survival after BTLVR was not superior to that after UTLVR even though the former group appeared to have a lower risk preoperatively because of younger age, higher arterial oxygen tension, more advantageous anatomy, and better functional status. Despite thoracoscopic LVR, the actuarial mortality rate approached 30% at 3 years, and this calls into question whether this procedure offers any survival advantage to patients with end-stage emphysema.     

Reduced incidence of atrial fibrillation with minimally invasive direct coronary artery bypass

Background. Atrial fibrillation (AF) is a frequent complication after coronary artery bypass graft (CABG) surgery. The purpose of this study was to determine the incidence of postoperative AF after minimally invasive direct coronary artery bypass (MIDCAB) in comparison with CABG.

Methods. Between November 1995 and May 1997, 96 MIDCAB procedures were performed. During the same period, 42 patients underwent traditional single CABG using the left internal mammary artery graft (S-CABG). The incidence of in-hospital AF, defined as a sustained episode requiring treatment, was compared between the two groups.

Results. There was no difference in age, ejection fraction, or preoperative risk score between the groups. The use of β-blockers before or after surgery was not different. The incidence of postoperative AF in the first 6 weeks after surgery was 4% (4 of 96) for MIDCAB and 28% (12 of 42) for S-CABG (p = 0.003). Patients with postoperative AF were older than those without AF (AF 75.5 ± 13.2, non-AF 64.4 ± 10.9, p = 0.005). MIDCAB patients had a shorter hospital stay (4.0 ± 1.2 versus 7.0 ± 5.1 days, p < 0.05). Increased hospital stay attributable to AF was 0.6 ± .5 days for MIDCAB and 0.9 ± .2 days for S-CABG patients. There were no hospital deaths in either group.

Conclusions. The incidence of postoperative AF after single vessel bypass surgery is reduced to a very low level after MIDCAB in comparison with CABG.     

Reversibility of Cardiac Dysfunction After Valve Replacement in Elderly Patients With Severe Aortic Stenosis

Background. The role of aortic valve replacement for aortic stenosis has not been fully defined in terms of the postoperative reversibility of cardiac dysfunction and pulmonary hypertension in elderly patients.

Methods. Cardiac function, assessed by radioisotope ventriculography and catheterization data, was evaluated before and after operation, and their results were compared between preoperative and postoperative data in each group of younger patients (<69 years, group I, n = 29) and elderly patients (≥70 years, group II, n = 21).

Results. One month postoperatively the peak ejection rate determined by radioisotope ventriculography improved significantly in comparison with the preoperative value in elderly patients (preoperatively, 228 ± 38 versus postoperatively, 319 ± 116% end-diastolic volume per second, p < 0.05), although their preoperative peak ejection rate was severely depressed. The postoperative peak filling rate of the elderly group was not completely reversible to almost normal value, whereas that of the younger group was completely reversible. Early diastolic peak filling rate (one-third peak filling rate) was not reversible in both two groups. Pulmonary hypertension in the elderly patients was reversible to postoperative almost normal pulmonary artery pressure despite the severity of aortic stenosis (systolic pulmonary artery pressure preoperatively, 37 ± 16 mm Hg versus postoperatively, 25 ± 5 mm Hg, p < 0.02; diastolic pulmonary artery pressure preoperatively, 15 ± 6 mm Hg versus postoperatively, 10 ± 4 mm Hg, p < 0.05).

Conclusions. Both cardiac dysfunction, reflected by reduction of peak ejection rate, and pulmonary hypertension in elderly patients with severe aortic stenosis were reversed, reaching almost normal values 1 month after operation.