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.     

Adjustable Model of Chronic Left Ventricular Dysfunction

Background. As an adjunct to the development of skeletal muscle-powered left ventricular assist devices, an adjustable model of chronic left ventricular failure was developed.

Methods. Implantation of a left ventricular balloon to induce heart failure was accomplished via left thoracotomy. Upon recovery, left ventricular failure was simulated by manipulation of left ventricular balloon volume to chronically raise left atrial pressure.

Results. Left atrial pressure increased from a baseline of 9.3 ± 0.7 mm Hg to 18.5 ± 1.2 mm Hg, 20.2 ± 1.8 mm Hg, and 26.0 ± 1.2 mm Hg by the 2nd, 6th, and 10th postoperative week, respectively. Cardiac index declined from a baseline of 4.4 ± 0.3 L · min⁻¹ · m⁻², reaching stability by the 8th postoperative week at 3.0 ± 0.4 L · min⁻¹ · m⁻². Stroke volume index declined from 1.12 ± 0.1 mL · kg⁻¹ · beat⁻¹ to 0.60 ± 0.1 mL · kg⁻¹ · beat⁻¹ by the 10th postoperative week. Mean survival was 75 ± 7 days. Causes of death included left ventricular failure, thromboembolism, and euthanasia.

Conclusions. This method of simulating chronic left ventricular dysfunction proved to be stable and adjustable and has been useful in the development of ventricular assist systems.     

Effects of Cardiomyoplasty on Right Ventricular Filling During Volume Loading

Background. Although cardiomyoplasty (CMP) is thought to improve ventricular systolic function, its effects on ventricular diastolic function are not clear. Especially the effects on right ventricular diastolic filling have not been fully investigated. Because pericardial influences are more pronounced in the right ventricle than in the left ventricle, CMP with its external constraint may substantially impair right ventricular diastolic filling.

Methods. Fourteen purebred adult beagles were used in this study. Seven underwent left posterior CMP, and 7 underwent a sham operation with a pericardiotomy and served as controls. Four weeks later, the hemodynamic effects of CMP were evaluated by heart catheterization before and after volume loading (central venous infusion of 10 mg/kg of 4.5% albumin solution for 5 minutes).

Results. In the CMP group, mean right atrial pressure and right ventricular end-diastolic pressure increased significantly from 3.1 ± 1.2 mm Hg to 6.1 ± 2.0 mm Hg (p < 0.001) and from 4.0 ± 1.8 mm Hg to 9.6 ± 2.5 mm Hg (p < 0.001), respectively. Volume loading in the control group did not significantly increase either variable. Right ventricular end-diastolic volume and stroke volume did not change significantly (from 53 ± 9.3 mL to 60 ± 9.0 mL and from 20 ± 2.3 mL to 21 ± 3.2 mL, respectively) in the CMP group. In the control group, however, right ventricular end-diastolic volume and stroke volume increased significantly from 45 ± 7.7 mL to 63 ± 14 mL (p < 0.05) and from 18 ± 4.3 mL to 22 ± 4.2 mL (p < 0.05), respectively.

Conclusions. These results suggest that CMP may reduce right ventricular compliance and restrict right ventricular diastolic filling in response to rapid volume loading because of its external constraint.     

Aortic valve replacement in severe aortic stenosis with left ventricular dysfunction: determinants of cardiac mortality and ventricular function recovery

Objective: The influence of left ventricular (LV) dysfunction on survival of patients with severe aortic stenosis is poorly characterized. Few data are available about preoperative predictors of cardiac mortality and LV function recovery after aortic valve replacement of such patients. The aim of our study was to examine the outcome and the preoperative predictors of postoperative cardiac death and of LV function recovery in these patients. Methods: We evaluated 85 consecutive patients with severe aortic stenosis (aortic valve area <1 cm²) and severe depression of LV ejection fraction (EF) <35% at cardiac catheterization. Among them, 52 underwent aortic valve replacement and they were compared to patients who were not operated on. All patients had a mean clinical follow-up of 53 months and 94% of them had a mean echocardiographic follow-up of 14 months after aortic valve replacement. Results: The mean baseline characteristics included: LVEF 28±6%, peak-to-peak transvalvular gradient 51±29 mmHg, aortic valve area 0.63±0.25 cm². Thirty-three patients did not undergo aortic valve replacement: 32 of them died within 3 years. Fifty-two patients underwent aortic valve replacement and 16 had a concomitant coronary bypass surgery. In-hospital mortality was 8%. Postoperative NYHA functional class changed from 2.84±0.67 to 1.43±0.44 (P<0.001) and LVEF from 29±6% to 43±10% (P<0.001). At follow-up 10 patients died of heart disease. By multivariate analysis, preoperative LV end-systolic volume index (ESVI) was the only covariate of cardiac death (LVESVI/10 ml/m², OR 1.3, CI 1.1–1.8, P<0.028). By using a receiver operating characteristic curve, LVESVI≤90 ml/m² was the best cut-off value (sensitivity and specificity 78%) to fit with a better survival (93% vs. 63%, P<0.01) and with LVEF recovery after aortic valve replacement (EF improved by 15±10% vs. 8±5%, P<0.001). Conclusions: Despite LV dysfunction, aortic valve replacement appears to change drastically the natural history of severe aortic stenosis. Preoperative LV levels predict different postoperative survival rate and LVEF recovery.     

Evidence for palliative enlargement of the right ventricular outflow tract in severe tetralogy of Fallot

Objective: If the pulmonary artery (PA) tree in patients with Fallot's tetralogy (TOF) is extremely hypoplastic, a shunt procedure may be difficult and not desirable because of side-effects. Moreover, the failing catch-up growth of the pulmonary annulus is well known. In patients with a severe form of TOF, we performed palliative transannular patching of the right ventricular outflow tract. The early and long-term follow-up was evaluated. Methods: Eleven patients (93 days (10–245 days); 3.5±0.7 kg (2.5–4.3 kg)) had highly symptomatic TOF (Hb: 18±2 g/dl, SO₂: 68±11%); angiographic diameters: RPA: 4.1 mm (2.5–6.4 mm), LPA: 3.4 mm (1.6–7.0 mm), PA trunc: 4.4 mm (2.5–7.0 mm). All 11 underwent transannular enlargement of the right ventricular outflow tract without closure of the ventricular septum defect. A PA index (cross-sectional area of the pulmonary arteries to BSA) was used to compare pre- and postoperative data. For follow-up, the patients were repetitively examined clinically and echocardiographically. Results: Preoperative PA index was 87±40 mm²/m² (normal: 330±35 mm²/m²). Postpalliation angiograms (age: 10–14 months) demonstrated a significant catch-up growth in nine patients (PA index from 99±40 to 310±54 mm²/m²) and inadequate growth in two patients (PA index 63 and 115 mm²/m²). Perioperative mortality was zero. Ten patients (43 months; 6–105 months) underwent elective repair. Six patients received pulmonary homograft valves (6–15 years after repair) because of severe pulmonary valve insufficiency and severe RV dilation. Complications: One patient died 10 months postpalliation due to pneumonia, one patient received a pacemaker after repair and died (2 months post-repair) due to pacemaker failure, a 5-year-old patient died 1 month after repair due to sepsis. All eight long-term survivors (12–17years) are in excellent clinical condition. Echocardiography revealed good RV function and near normal diameters at peak systolic pressures between 25 and 50 mmHg. Only one patient developed brady-arrhythmia; a pacemaker was implanted 8 years after repair and 2 years after homograft implantation. Conclusions: In a very severe form of TOF, palliative right ventricular outflow tract construction may provide the potential for complete repair. In the presented high-risk patient group, mortality was not related to the hypoplastic pulmonary arteries. Obviously, all patients need pulmonary valve implantation in the long run.     

Selected ventriculoplasty for idiopathic dilated cardiomyopathy with advanced congestive heart failure: midterm results and risk analysis

Background: To treat advanced heart failure due to idiopathic dilated cardiomyopathy, surgical ventricular restoration with mitral reconstruction was conducted and evaluated. Methods: In 95 patients (81 men, mean age: 54 years), New York Heart Association class III/IV was 44/51, and 33 patients (36%) were inotropic dependent preoperatively. Mitral regurgitation (≥2+) was noted in all patients. All patients underwent left ventriculoplasty (septal anterior ventricular exclusion in 38, partial left ventriculectomy in 57) and mitral reconstruction (repair 53, replacement 42). Fifty-two patients (55%) had concomitant tricuspid repair. Intra-aortic balloon pumping and left ventricular assist device was used in 24 patients and two patients, respectively. Results: Hospital mortality was 11.6% (11 of 95), with 6.6% (5 of 76) in elective and 31.6% (6 of 19) in emergency operations. The ejection fraction and cardiac index increased from 22.3 ± 6.3% to 27.2 ± 8.0% and from 2.3 ± 0.5 ml/m²/min to 2.8 ± 0.5 ml/m²/min, respectively (p < 0.001). The endodiastolic volume index, endosystolic volume index and diastolic dimension decreased from 232.9 ± 56.1 ml/m² to 160.0 ± 49.8 ml/m², from 178.9 ± 46.7 ml/m² to 113.8 ± 44.7 ml/m² and from 82.0 ± 9.0 mm to 68.9 ± 11.6 mm, respectively (p < 0.001). Late death occurred in 27 patients with 22 cardiac deaths. The mean NYHA class was 1.7 among the survivors. One-, 3- and 5-year survival rates were 72.8%, 61.4% and 50.5%, respectively. In the 62 patients who were non-inotropic dependent preoperatively, 1-, 3-, and 5-year survival rates (81.8%, 73.7% and 62.9%) were significantly better than the inotropic-dependent group (55.3%, 37.3% and 28.0%). Patients with mitral annuloplasty showed a significantly higher 5-year survival rate than patients with mitral valve replacement (59.6% vs 43.6%) in univariate analysis. By application of the exclusion site selection method, the two different ventriculoplasty procedures did not show significant difference in survival rates. Multivariate analysis showed that preoperative inotropes and old age were significant predictors for postoperative mortality. Conclusion: The selected ventriculoplasty in combination with mitral annuloplasty is a useful option for patients with an extremely dilated left ventricle in idiopathic dilated cardiomyopathy. Surgery should be considered before inotropic dependency occurs when prior medical treatment has failed.     

Partial left ventriculectomy for idiopathic dilated cardiomyopathy: early results and six-month follow-up

Background. Recent reports show that partial left ventriculectomy improves hemodynamic and functional status in patients with dilated cardiomyopathy. This study sought to determine the effects of partial left ventriculectomy on clinical outcome and left ventricular function during 6-month follow-up.

Methods. Twenty-two patients underwent partial left ventriculectomy. Mitral valve repair was performed whenever possible, otherwise the valve was replaced. Hemodynamic and functional data were obtained at baseline, as well as 2 weeks and 6 months postoperatively.

Results. Overall, 7 of 22 patients died; there were three early and four late deaths. One-year survival was 68% ± 10%. Ejection fraction increased from 23.9% ± 6.8% before the operation to 40.7% ± 12.5% at 2 weeks and to 36.8% ± 7.7% at 6 months (p < 0.001, for both). The cardiac index before the operation, at 2 weeks, and at 6 months was 2.3 ± 0.8, 2.9 ± 0.6, and 3.4 ± 1.0 L/m² per minute, respectively (p = 0.035, and p = 0.009, compared with baseline). The increase in ejection fraction 2 weeks postoperatively was less in patients with left circumflex artery dominance (10.9% ± 3.2% compared with 19.9% ± 10.7%, respectively, p = 0.017). At 6-month follow up, all surviving patients except one improved New York Heart Association functional class when compared with preoperative status (from 3.8 ± 0.4 to 1.4 ± 0.6, p = 0.0002).

Conclusions. Early hemodynamic improvement after partial left ventriculectomy was maintained during midterm follow-up.     

Unbalanced atrioventricular septal defect with parachute valve

A 5-month-old male patient presented with right-dominant unbalanced atrioventricular septal defect and left-sided parachute valve, and underwent successful biventricular repair. Because of the presence of a small left ventricle, left atrium, and a single left papillary muscle, an additional orifice was created in the left-sided atrioventricular valve with artificial partitioning of the right-sided atrioventricular valve. There was no evidence of mitral stenosis or regurgitation on follow-up echocardiography.     

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.     

Biventricular repair in children with atrioventricular septal defects and a small right ventricle: anatomic and surgical considerations

OBJECTIVE: We sought to characterize morphology and to evaluate a strategy of using biventricular repair in patients with a small right ventricle and an unbalanced atrioventricular septal defect. METHODS: Thirty-eight children with a small right ventricle and an atrioventricular septal defect underwent operative therapy. Thirty-two had biventricular repair, and 6 had single-ventricle palliation. A small right ventricle was defined on the basis of echocardiographic measurements expressed as the atrioventricular valve index (ie, right atrioventricular valve/left atrioventricular valve area) and as the ratio of right ventricular to left ventricular length. Validation of measurements in patients with a small right ventricle and an atrioventricular septal defect was achieved by comparison with balanced case-matched control subjects with atrioventricular septal defects. RESULTS: Children with a small right ventricle and an atrioventricular septal defect had a lower atrioventricular valve index (mean, 0.41 +/- 0.1 vs 0.52 +/- 0.1 [control], P < .0001) and lower right ventricular/left ventricular length ratio (0.78 +/- 0.1 vs 0.99 +/- 0.17 [control], P < .0001). Children with a small right ventricle undergoing single-ventricle palliation had the smallest right ventricular dimensions. There were 4 operative deaths. Three patients with a small right ventricle and an atrioventricular septal defect who underwent biventricular repair and had an atrioventricular valve index of less than 0.50 required early reoperation for right ventricular inadequacy. A restrictive atrial fenestration was created in 11 infants. Survival at 10 years was 87% for patients undergoing biventricular repair versus 100% for control subjects (P = .042). CONCLUSIONS: Extending the use of biventricular repair in properly selected patients with a small right ventricle and an atrioventricular septal defect is feasible. An atrial fenestration improves the physiologic tolerance to repair in selected patients. The use of biventricular repair in children with atrioventricular valve indexes of less than 0.50 requires caution.     

Update 2001: Right latissimus dorsi cardiomyoplasty augments left ventricular systolic performance

As Originally Published in 1993: Right Latissimus Dorsi Cardiomyoplasty Augments Left Ventricular Systolic Performance by Stephen E. Park, MD, Brian L. Cmolik, MD, Robert R. Lazzara, MD, Dennis R. Trumble, MS, and James A. Magovern, MD. Department of Surgery, Allegheny General Hospital, Surgical Research, Allegheny-Singer Research Institute, and Allegheny Campus, The Medical College of Pennsylvania, Pittsburgh, Pennsylvania, USA

We hypothesized that the right latissimus dorsi cardiomyoplasty augments left ventricular performance. Five dogs underwent staged right latissimus dorsi cardiomyoplasty. Ventricular function was studied 1 to 3 weeks later. Left ventricular pressure was measured with a micromanometer and left ventricular dimensions with piezoelectric crystals. Inferior vena caval occlusion was used to vary preload. Pressure-volume data were collected with the muscle unstimulated and stimulated at 1:2 and 1:1 muscle/heart ratios. The end-systolic pressure-volume relation (mm Hg/mL), stroke work, preload recruitable stroke work, left ventricular end-diastolic volume, and the diastolic relaxation constant were calculated and expressed as mean ± standard deviation. Stimulated beats at a 1:2 ratio showed an increase in stroke work of 42.1% (978 ± 381 to 1,390 ± 449 g · cm; p < 0.01) and preload recruitable stroke work of 28.8% (59.4 ± 20.7 to 76.6 ± 11.0 g · cm/cm³; p = 0.05) compared with the unstimulated beats. With the stimulator on at 1:1, smaller changes occurred: stroke work increased 9% (1,167 ± 390 to 1,273 ± 363 g · cm; not significant) and preload recruitable stroke work increased 27% (63.9 ± 22.7 to 80.9 ± 23.1 g · cm/cm³; p = 0.05). There were no significant changes in the end-systolic pressure-volume relation. The diastolic relaxation constant did not change at 1:1 (36 ± 9.7 to 37 ± 6.4 ms; not significant) or 1:2 (36 ± 9.3 to 39 ± 8.2 ms; not significant). Left ventricular end-diastolic volume was unchanged at 1:1 (34 ± 10.7 to 32 ± 10.3 mL) and at 1:2 (31 ± 9.0 to 32 ± 8.7 mL). Right unconditioned latissimus dorsi cardiomyoplasty in anesthetized dogs with normal hearts resulted in enhanced systolic work and contractility with no change in diastolic relaxation at stimulation rates of 1:2 and 1:1.     

The spectrum of double-outlet right atrium including hearts with three atrioventricular valves

Double-outlet right atrium (DORA) is characterized by simultaneous right atrial emptying into both ventricles. Ventriculoatrial septal malalignment is the cardinal morphological feature. Three cases are presented to depict two major types of DORA-DORA with a malaligned atrial septum and DORA with a malaligned ventricular septum. We describe two subtypes of each form of DORA: DORA with a malaligned atrial septum presents with either a common atrioventricular (AV) junction (guarded by a common AV valve) or with a single AV junction (due to the absence of the left AV junction). DORA with a malaligned ventricular septum may be associated with a right ventricle (RV) that is adequate for biventricular repair or a severely hypoplastic RV not compatible with biventricular repair. DORA with a malaligned ventricular septum is closely related to typical straddling of the tricuspid valve. Peculiarly, DORA with a malaligned ventricular septum presents three AV valves at the AV junction and is associated with an abnormal disposition of the AV conduction axis. Clear understanding of the morphology of these lesions is important in preventing a surgical misadventure at the crux of the heart.     

Right internal thoracic artery through the transverse sinus in myocardial revascularization

Background. A major concern in evaluating dynamic cardiomyoplasty has been whether the synchronous stimulation of latissimus dorsi muscle is essential for benefit or not. We studied 10 patients to determine the efficacy of the systolic augmentation generated by the synchronous electrical stimulation of the latissimus dorsi muscle.

Methods. Left ventricular ejection fraction, end-systolic and end-diastolic volume indexes, and stroke volume index obtained during resting, peak exercise, and recovery periods (“on” values) were compared with those obtained 1 week after cessation of electrical stimulus (“off” values). Double product and estimated total body oxygen consumption at peak exercise were also calculated and compared.

Results. Higher ejection fractions (0.36 ± 0.07 versus 0.33 ± 0.06 at rest, 0.40 ± 0.07 versus 0.33 ± 0.07 peak exercise, and 0.37 ± 0.06 versus 0.31 ± 0.06 at recovery) and lower end-systolic volume indexes with relatively constant end-diastolic volume indexes were observed with the cardiomyostimulator on. Further, exercise response was better with the cardiomyostimulator on. Double product indirectly reflected better myocardial oxygen supply/demand ratio when on at peak exercise (17 ± 2.2 mm Hg × beats/min × 10⁻³ for on versus 19 ± 2.6 mm Hg × beats/min × 10⁻³ for off). Estimated total body oxygen consumption was improved at peak exercise when the cardiomyostimulator was functional (12 ± 2.7 mL · kg⁻¹ · min⁻¹ versus 11 ± 2.6 mL · kg⁻¹ · min⁻¹).

Conclusions. Current data suggest a true systolic assist during synchronous contractions of the latissimus dorsi muscle. It is thought, therefore, that synchronous electrical stimulation is essential for maximum benefit and all the beneficial effect of cardiomyoplasty certainly cannot be attributed to simple wrapping itself.     

Impact of postoperative blood pressure control on regression of left ventricular mass following valve replacement for aortic stenosis

Objective: Considerable left ventricular (LV) hypertrophy sometimes remains after aortic valve replacement (AVR) for aortic stenosis. For this issue, most previous studies have focused solely on transprosthetic pressure gradient, although true problem is not the pressure gradient itself but an elevated LV pressure. This study investigated the impact of blood pressure on postoperative LV mass regression, which had been overlooked in previous studies. Methods: Seventy-nine adult patients with pure aortic stenosis who were treated with AVR using bileaflet mechanical valves underwent echocardiography before surgery, around 6 months later (‘early’), and 2–3 years later (31.7±14.7 months, ‘late’). Patients were divided into two groups whether postoperative systolic blood pressure was below (n=47; N group) or above 130 mmHg (n=32; H group) following recommendation of WHO-ISH and JNC 7th report. Preoperative LV mass (g/m²) did not differ significantly (232±80 vs. 243±76, P=0.91). Results: LV mass became significantly smaller and regression was significantly more effective in N group than in H group both at ‘early’ (145±43 vs. 180±54, regression against preoperative value 34.6±19.1 vs. 19.9±26.6%, P=0.007) and ‘late’ (132±41 vs. 178±51, regression 41.1±16.0 vs. 21.0±27.0%, P<0.001) evaluations. Regression between ‘early’ and ‘late’ evaluations was significant only in N group (P=0.012). The LV mass index returned to the normal range at ‘late’ evaluation in 52.1% of N group and 12.5% of H group patients (P<0.001), and 25 out of 29 patients without residual LV hypertrophy were N group patients. Multivariate analyses revealed that preoperative LV mass index (P<0.001) and postoperative systolic blood pressure (P=0.007) showed significant influence on postoperative LV mass index, and postoperative systolic blood pressure alone significantly (P<0.001) influenced the regression ratio of the LV mass against the preoperative value. No prosthesis related variables (size, orifice area index, pressure gradient) had significant influence. Conclusions: For LV mass regression after AVR, postoperative blood pressure appeared to be more important than prosthesis selection. Controlling the systolic blood pressure below 130 mmHg was beneficial, which coincided with recommendation of WHO-ISH and JNC 7th report despite the pressure drop due to prosthesis in the aortic position.     

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.     

Vascular delay and intermittent stimulation: keys to successful latissimus dorsi muscle stimulation

Background. The goal of this study was to obtain physiologically significant increases in peak left ventricular (LV) systolic pressure and stroke volume with latissimus dorsi muscle (LDM) stimulation in cardiomyoplasty (CMP). We hypothesized that preserving LDM integrity by vascular delay and intermittent stimulation would significantly increase LDM cardiac assistance.

Methods. In 4 control dogs and 12 dogs that had undergone a vascular delay (VD) procedure, LV dysfunction was induced by intracoronary microsphere injections. Cardiomyoplasty surgery was performed 14 days later, followed by progressive LDM conditioning. In the control dogs and in 6 of the VD dogs, the LDM was stimulated 24 hours per day (VD plus constant stimulation [CS]). In the other 6 VD dogs, LDMs were stimulated on a daily schedule of 10 hours on and 14 hours off (VD plus interrupted stimulation [IS]). Latissimus dorsi muscle stimulated beats were compared with nonstimulated beats 9 weeks later.

Results. In the control dogs, LDM stimulation had minimal effects. In VD + CS and VD + IS, LDM stimulation increased peak LV pressure, stroke volume, stroke work, and stroke power (p < 0.05). However, these changes were greater in the VD + IS group, in which LDM stimulation increased peak aortic pressure by 17.6 ± 1.7 mm Hg, peak LV pressure by 19.7 ± 1.1 mm Hg, peak positive LV dp/dt by 398 ± 144 mm Hg per second, stroke volume by 5.1 ± 0.7 mL, stroke work by 10.9 ± 0.9 gm · m, and stroke power by 122.7 ± 11.6 gm · m per second (p < 0.05 compared with VD + CS). Quantitative morphometric analysis showed minimal LDM degeneration in the VD + IS group (7.5% ± 1.1%), and VD + CS group (10.5% ± 4.5%) compared with the control group (29.5% ± 4.5%, p < 0.05).

Conclusions. VD and IS considerably increased the LV assistance with LDM stimulation. Further studies of this combined approach to CMP should be planned.     

Comparison of the morphologic and vascular reactivity of the proximal and distal radial artery

Background. Variations in the morphology and vascular reactivity of the proximal and distal radial artery might influence its performance as a bypass conduit.

Methods. The morphologic and functional characteristics of the proximal and distal RAs were compared with those of the left and right internal mammary arteries by using histologic and in vitro organ bath techniques.

Results. Proximal RA had a significantly greater medial cross-sectional area compared with that of the distal RA (2.48 ± 0.27 mm² compared with 1.86 ± 0.21 mm², p < 0.05), which were both significantly greater than the left internal mammary artery (0.54 ± 0.09 mm²) or the right internal mammary artery (0.67 ± 0.03 mm²). Proximal RA had a significantly greater response to 90 mmol/L potassium chloride than that of distal RA (88.4 ± 7.3 compared with 60.2 ± 10.3 mN, p < 0.05), and both contracted more than the left internal mammary artery (30.3 ± 2.9 mN) and the right internal mammary artery (32.6 ± 4.1 mN). There was no difference in the response to noradrenaline and adrenaline between proximal and distal RA, both of which contracted more than the left and right internal mammary arteries.

Conclusions. When choosing a segment of RA for use as a bypass conduit, regional variations in biologic properties should be considered.     

Successful biventricular repair after initial Norwood operation for interrupted aortic arch with severe left ventricular outflow tract obstruction

Background. Management of newborns with interrupted aortic arch (IAA) remains challenging. Associated severe left ventricular outflow tract obstruction (LVOTO) have often led to increased mortality with neonatal biventricular repair. We review our experience with an alternative approach for this complex surgical problem.

Methods. From May 1991 to June 1999, 28 neonates were treated for IAA. Thirteen of 28 neonates (46%) had type B IAA, ventricular septal defect (VSD) and severe LVOTO (Z value –2 to –7; mean –5 ± 1.7). Mean age was 8 days (3 to 23 days old) with average weight of 3.3 kg (2.4 to 4.2 kg). Eight of 13 (62%) had anomalous right subclavian artery. Ten of 13 (77%) had thymic aplasia and chromosome 22 region q11 deletion. All 13 patients were treated initially with a modified Norwood procedure.

Results. There were no perioperative deaths. Complications included 2 patients with recurrent arch stenosis treated with balloon dilatation. Two patients had systemic arterial shunt revision. Follow-up ranged from 2 to 99 months old (mean 39 months). There were 2 late deaths unrelated to any operation. Nine of 12 patients had a second stage palliation consisting of a bidirectional Glenn shunt. Six patients went on to have biventricular repairs (3 Ross-Konno, 2 Rastelli, 1 VSD closure with LVOT resection). One patient had a modified Fontan operation and 5 patients are awaiting potential biventricular repair.

Conclusions. Children with IAA and severe LVOTO may be managed by initial Norwood palliation with an excellent outcome likely. This initial “univentricular” approach has enabled eventual successful biventricular repair despite severe LVOTO.     

Incomplete atrioventricular septal defect with hypoplastic left ventricle and left atrioventricular valve stenosis

A 2-month-old male infant with incomplete atrioventricular septal defect associated with a hypoplastic left ventricle and left atrioventricular valve stenosis successfully underwent biventricular repair. Echocardiography showed marked dilatation in the right ventricle and a diminutive left ventricle. However, the left ventricular chamber occupied the apex. Left atrioventricular valve stenosis was due to a solitary papillary muscle. Cardiac catheterization showed pulmonary/systemic flow ratio of 3.61, left ventricular end-diastolic volume of 63% of normal, and right ventricular end-diastolic volume of 324% of normal. During surgical repair, the solitary papillary muscle was divided longitudinally and the ostium primum was closed with a bovine pericardium. Postoperative left ventricular function was appropriate. Even when the preoperative end-diastolic left ventricular volume is small, if the left ventricle chamber is at the apex, then the left ventricular performance can be expected to be appropriate to tolerate the volume load after ostium primum closure.     

Repair of anomalous left main coronary artery arising from the pulmonary artery in infants: long-term impact on the mitral valve

Background. Infants presenting with anomalous left coronary artery off the pulmonary artery (ALCAPA) are generally in heart failure and often have significant mitral valve regurgitation (MR). Although establishing a dual coronary circulation is the procedure of choice, there remains controversy as to how the mitral valve is handled.

Methods. We reviewed our experience with this lesion at St. Louis Children’s Hospital. Over the past 15 years, 17 infants under 18 months of age have undergone repair, with all but one being treated with reimplantation of the left coronary artery into the aorta; the other underwent the Takeuchi procedure (intrapulmonary artery baffle) and was excluded from this evaluation. The average age and weight at operation were 0.5 ± 0.3 years and 6.1 ± 1.9 kg, respectively. All presented with varying degrees of heart failure and 9 patients also had either moderate or severe MR.

Results. There was one early and no late deaths after reimplantation of the left coronary artery. The left ventricular function postrepair improved from a preoperative shortening fraction of 0.19 ± 0.09 to 0.34 ± 0.08 (p < 0.01). Moderate or severe MR was present in 2 patients postoperatively, and both developed significant obstruction in the left coronary artery postoperatively as well. Both underwent mitral valve repair and revascularization of the left coronary artery.

Conclusions. Excellent results can be obtained in the treatment of this very high-risk group of patients. Mitral valve repair is not generally necessary at the time of the initial operation. However, should MR recur or persist late, it may herald the presence of a coexistent, significant coronary stenosis. Cardiac catheterization should be performed to assess the patency of the left coronary artery before performing mitral valve surgery.