Bidirectional Glenn procedure improves the mechanical efficiency of a total cavopulmonary connection in high-risk fontan candidates

Effect of ventricular volume before unloading in a systemic ventricle supporting the Fontan circulation

The influence of volume overload on ventricular performance has been previously investigated but primarily with respect to the duration of overload. The aim of the present study was to elucidate whether the magnitude of the preoperative volume overload, represented by the ventricular volume, has any effect on ventricular performance long after the Fontan operation in patients with tricuspid atresia. We evaluated consecutive changes in hemodynamic catheterization data obtained at 1, 5, and 10 years after primary Fontan repair. The variables were compared between patients with larger (n = 20) and smaller (n = 21) ventricles (preoperative end-diastolic volume [percentage of predicted] 262 ± 33%, maximum 320% vs 182 ± 22%, minimum 133%, respectively). In a subgroup of patients (n = 33) who underwent symptom-limited exercise at 10.7 ± 3.0 postoperative years, the peak oxygen uptake was measured, and the potential predictors were interrogated. The difference in ventricular contractility between the groups tended to increase with time, with those with a larger ventricle showing poorer contraction, irrespective of whether it was assessed in a load-dependent (ejection fraction) or load-independent (end-systolic elastance) manner. The differences in these variables reached statistical significance at 10 years (p = 0.028 and p = 0.032). Multivariate analysis indicated a larger ventricle was an independent risk factor of poorer aerobic capacity (p = 0.047). In conclusion, ventricular performance was less preserved in those with a larger ventricle, which might result in suboptimal aerobic capacity. Our findings suggest not only early unloading, but also avoidance of excessive volume overload is of importance to minimize the deleterious effect of volume overload on an inherently susceptible ventricle.

Intracardiac cavopulmonary connection in patients with univentricular heart using intra-atrial lateral tunnel and intra-atrial conduit techniques

BACKGROUND

In this study, we analyzed the time course of hemodynamic efficiency and follow-up in Fontan candidates who underwent the bidirectional Glenn procedure for staged intracardiac cavopulmonary connection (ICPC).

METHODS

Between 1991 and 2008, 52 patients with univentricular heart (mean age, 3.3 years; range, 2-8 years; 27 female patients [51.9%]) underwent ICPC. The cardiac malformations were as follows: tricuspid atresia, 25 cases (48.0%); common ventricle, 16 cases (30.7%); and pulmonary atresia with intact ventricular septum, 11 cases (21.1%). The intracardiac cavopulmonary procedure was indicated for all 52 cases. In 42 patients (80.7%), an intra-atrial lateral tunnel was constructed with a bovine pericardium patch. In the last 10 consecutive cases (19.3%), we performed a modified surgical technique in which we implanted an intra-atrial corrugated bovine pericardium tube sutured around the superior and inferior vena cava ostium. In all cases, a 4-mm fenestration was made to reduce the intratunnel pressure. All 52 patients had previously undergone a Glenn operation.

RESULTS

There were 2 hospital deaths (3.8%) and no recorded late deaths. During the follow-up, all patients were medicated with antiplatelet drugs. To evaluate the hemodynamic performance, we used Doppler echocardiography, computed tomography, and magnetic nuclear resonance studies. There were no prosthesis thromboses during this followup period. To evaluate cardiac arrhythmias, we conducted a Holter study. The last 10 patients with an intra-atrial conduit (IAC) presented with sinus rhythm and no arrhythmias during the last 4 years. The 50 surviving patients (96.1%) have been followed up for 6 to 204 months; all these patients are free of reoperation.

CONCLUSION

The Glenn operation, which is performed at an early age, prepares the pulmonary bed to receive the ICPC. The midterm results of the intracardiac Fontan procedure seem to be good. The modified surgical procedure (IAC) can be a good alternative technique to the Fontan procedure in suitable patients.

Unnatural history of the right ventricle in patients with congenitally malformed hearts

The long-term outcome of patients with congenitally malformed hearts involving abnormal right ventricular morphology and haemodynamics is variable. In most instances, the patients are at risk for right ventricular failure, in part due to morphological differences between the right and left ventricles and their response to chronic volume and pressure overload. In patients after repair of tetralogy of Fallot, and after balloon valvotomy for valvar pulmonary stenosis, pulmonary regurgitation is the most significant risk factor for right ventricular dysfunction. In patients with a dominant right ventricle after Fontan palliation, and in those with systemic right ventricles in association with surgically or congenitally corrected transposition, the right ventricle is not morphologically capable of dealing with chronic exposure to the high afterload of the systemic circulation. In patients with Ebstein's malformation of the tricuspid valve, the degree of atrialisation of the right ventricle determines how well the right ventricle will function as the pump for the pulmonary vascular bed.

Bidirectional cavopulmonary shunt with additional pulmonary blood flow

There are some controversies regarding the usefulness of leaving additional pulmonary blood flow when establishing a bidirectional cavopulmonary shunt. From April 2002 to September 2008, 13 patients (mean age, 24 +/- 16 months) underwent a bidirectional cavopulmonary shunt procedure with fine adjustment of additional pulmonary blood flow, as an intermediate step before the Fontan operation. There were no hospital deaths. Modified Blalock-Taussig shunts were left during the bidirectional cavopulmonary shunt operation in 7 patients, and pulmonary bands were tightened in 4. The main pulmonary artery with a previous pulmonary band was left open in one case. Oxygen saturation increased from 74.5% +/- 7.4% to 84.6% +/- 1.9% after the operation, cardiothoracic ratio decreased from 55.9% +/- 6.1% to 53.2% +/- 3.4%, Left ventricular end-diastolic pressure decreased from 11.0 +/- 2.6 to 7.8 +/- 3.0 mm Hg, and mean pulmonary arterial pressure from 14.7 +/- 7.5 to 10.2 +/- 3.1 mm Hg. Pulmonary artery index did not change significantly. In our experience, additional pulmonary blood flow with adjustment in each patient at the time of shunt construction was an excellent temporary palliation prior to the Fontan operation.

Staged surgical approach in neonates with a functionally single ventricle and arch obstruction: pulmonary artery banding and aortic arch reconstruction before placement of a bidirectional cavopulmonary shunt in infants

The success rate of right-heart bypass surgery in patients with a functionally single ventricle (f-SV) and systemic obstruction is low. In patients with a high risk of subaortic stenosis, we performed an initial step of pulmonary artery banding (PAB) and arch reconstruction before placing a bidirectional cavopulmonary shunt (BCPS) in infants with or without Damus-Kaye-Stansel (DKS) anastomosis. We assessed the success of right-heart bypass surgery. Between October 2003 and August 2008, we performed surgery in 19 neonates (median age 5 days) with f-SV and arch obstruction. Extended aortic arch anastomosis, with or without distal arch augmentation, was performed in 10 patients, and subclavian flap aortoplasty was performed in 9 patients. The circumference of the PAB was determined as the individual patient's body weight in kilograms plus 16.2 +/- 3.7 mm. Eighteen of 19 infants (95%) underwent successful BCPS placement at a median age of 7.8 months. DKS anastomosis was performed concomitantly during BCPS placement in 11 infants in whom subaortic stenosis was morphologically suspected but not demonstrated physiologically. As our first-stage operation, arch reconstruction plus PAB provided high success rates for right-heart bypass operations. This strategy is not leading, but it is a reliable approach for progression along a Fontan pathway.

Outcomes of the bidirectional Glenn procedure in patients less than 3 months of age

OBJECTIVE

The bidirectional Glenn procedure is a well-established procedure performed as part of the single-ventricle palliation pathway. Numerous studies have highlighted the potential benefits of an "early" BDG procedure. The ideal age to perform the BDG procedure, however, remains uncertain. We report our experience with the BDG procedure in patients younger than 3 months.

METHODS

One hundred sixty-nine consecutive patients from 1998 to 2007 undergoing the BDG procedure were divided into 2 groups: younger than 3 months (n = 20) and older than 3 months. The groups were compared for 26 variables. All data were analyzed with Kaplan-Meier survival analysis and the Cox proportional hazard regression test to assess the probability of survival after the BDG procedure in both groups. A stepwise regression analysis was performed for identification of independent factors for postoperative oxygen saturation at hospital discharge.

RESULTS

The groups were comparable, with an equal distribution of patients with right-sided or left-sided single-ventricle anatomy. Although intensive care unit length of stay, ventilation time, and hospital length of stay were longer in the younger group, room air oxygen saturations at discharge, both early and late mortality, and time to the Fontan procedure were similar between groups. The independent variables found for death after the BDG procedure were preoperative mean pulmonary artery pressure, atrioventricular valve regurgitation, and postoperative oxygen saturations at hospital discharge. Survival in patients with hypoplastic left heart syndrome was comparable between groups after 5 years of follow-up.

CONCLUSION

The BDG procedure is feasible and safe in patients as young as 2 months of age, with early and late mortality equivalent to that seen in older patients.

Ventricular energetics in aortic root replacement for annuloaortic ectasia with aortic regurgitation

Aortic root replacement (Bentall operation) is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. We analyzed the mid-term results for left ventricular energetics after the Bentall operation for annuloaortic ectasia with aortic regurgitation. We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on transthoracic echocardiography data before, after, and approximately 1 year after the Bentall operation in 15 patients with annuloaortic ectasia with aortic regurgitation. Left ventricular volume was calculated by the Teichholz M-mode method. Ees and Ea were approximated as follows: Ees=mean blood pressure/minimal left ventricular volume, and Ea=systolic blood pressure/(maximal left ventricular volume--minimal left ventricular volume). Ea/Ees and SW/PVA were then calculated. Left ventricular volume was normalized with body surface area. Ees increased after the Bentall operation and around 1 year later (from 2.17+/-1.09 to 3.92+/-2.26 and 5.33+/-1.90 mmHg x m(2)/ml, P<0.001), thus resulting in an improvement in SW/PVA (from 68.8+/-8.2 to 70.9+/-9.5 and 74.7+/-5.2%, P=0.045). Ea also increased after the Bentall operation and 1 year later (from 1.77+/-0.61 to 2.88+/-1.28 and 3.54+/-1.43 mmHg x m(2)/ml, P<0.001). The mid-term results for ventricular contractility and efficiency after the Bentall operation for annuloaortic ectasia with aortic regurgitation are excellent and satisfactory.

Transition of ventricular function and energy efficiency after a primary or staged Fontan procedure

PURPOSE

The transitional changes of the ventricular function at different time points after total cavopulmonary connection (TCPC) were examined.

METHODS

A total of 29 patients were divided into a primary TCPC group and a staged TCPC group. In both groups, phase I was defined as within 2 months after TCPC and phase II as beyond at least a year after TCPC. Changes in ventricular end-diastolic volume (EDV), ventricular end-systolic elastance (Ees), effective arterial elastance (Ea), and ventriculoarterial coupling (Ea/Ees) were evaluated.

RESULTS

The results for the primary TCPC group are as follows. Phase I: The EDV decreased (P < 0.05). The Ees and Ea both increased (P < 0.05). Ea/Ees showed a tendency to increase (P = 0.08). Phase II: The EDV decreased (P < 0.05). The Ees increased significantly, and Ea showed no significant change. Ees/Ea showed a tendency to decrease (P = 0.07). The results for the staged TCPC group were as follows. Phase I: The EDV decreased significantly after bidirectional cavopulmonary shunt (BCPS). The Ees showed no significant change after BCPS and TCPC. Although Ea increased after BCPS (P < 0.05), it showed no significant change after TCPC. Ea/Ees showed no significant change. Phase II: The Ees increased (P < 0.05) without significant changes of EDV and Ea. As a result, Ea/Ees showed a tendency to decrease.

CONCLUSION

This study suggested improved ventricular function in both groups. These results suggest hemodynamic adaptation to the Fontan circulation. The deleterious effects on ventricular function caused by the Fontan procedure disappeared within a couple of years. This acute effect can be ameliorated by the staged approach to the Fontan circulation.

Factors Influencing Survival in Patients after Bidirectional Glenn Shunt

Clinical characteristics, echocardiographic values, and catheterization data of 45 patients with a functional univentricular heart who had a bidirectional Glenn shunt instituted between November 1994 and October 2006 were retrospectively reviewed. Median age at operation was 20 months (range, 9 months to 19 years). Median follow-up time after the bidirectional Glenn operation was 4 years (range, 1 day to 11 years). The early mortality rate was 4/45 (8.9%); overall mortality was 24.4%. Actuarial survival after a bidirectional Glenn shunt was 73% ± 8% at 5 years and 55% ± 17% at 10 years. In multivariate Cox proportional hazards analysis, heterotaxy syndrome and systemic right ventricle were independent predictors of mortality after the bidirectional Glenn shunt. Age at operation, oxygen saturation, previous surgery, a pulsatile Glenn shunt, cardiopulmonary bypass, postoperative pulmonary artery pressure, bilateral superior venae cavae, and Nakata index were not predictive of mortality. The presence of heterotaxy syndrome and systemic right ventricle in patients with a functional univentricular heart should lead to aggressive investigation and management strategies.

Long-term clinical outcome of atrial isomerism after univentricular repair

OBJECTIVES

We retrospectively reviewed the long-term outcome of atrial isomerism patients after Fontan completion.

METHODS

Since 1972, 58 patients underwent a palliative procedure prior to the Fontan-type operation. Twenty-eight out of 58 patients could not reach Fontan-type operation. Twenty-five patients underwent Fontan-type operation, and 12 of them expired less than five years after the Fontan completion. Eleven patients survived more than five years after the Fontan completion and were identified as long-term survivors. The mean follow-up period was 13+/-5 years.

RESULTS

During follow-up period, four of the 11 patients expired. The actuarial survival rates at 10, 15, and 20 years after univentricular repair (UVR) were 100%, 71.4%, and 53.6%, respectively. The significant predictors of long-term survival by univariate analysis were the staged strategy (p=0.019), total cavo-pulmonary connection with extracardiac conduit (p=0.019), and the absence of postoperative common atrioventricular valve regurgitation (p=0.040). Six out of the seven present survivors showed New York Heart Association class I activity. All present survivors' mean percutaneous oxygen saturation, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, single ventricular end diastolic volume index, and single ventricular ejection fraction were 88.8+/-6.8%, 11.0+/-2.6 mmHg, 5.8+/-2.0 mmHg, 104+/-37 mL/m2, and 52.0+/-6.5%, respectively.

CONCLUSIONS

There are still life-threatening problems 10 years after the UVR. However, the excellent performance status of the present long-term survivors suggests that these problems can all be overcome by the present strategies established for the Fontan-type operation.

Persistent antegrade pulmonary blood flow post-glenn does not alter early post-Fontan outcomes in single-ventricle patients

BACKGROUND

The bidirectional Glenn cavopulmonary anastomosis (BDG) represents the standard interim procedure in treatment of patients with single-ventricle physiology. Anterograde pulmonary blood flow (APBF) maintained after BDG has been shown both to improve and to complicate postoperative clinical course. We studied its effects on outcome after BDG and eventual Fontan completion.

METHODS

From November 1995 to November 2005, 60 patients underwent BDG and Fontan. All patients had APBF from the ventricle to the pulmonary artery at time of BDG. In group 1 (n = 39) APBF was maintained after BDG, whereas APBF was interrupted at BDG in group 2 (n = 21). Cardiac catheterization data, interstage morbidity, and postoperative outcome variables were recorded.

RESULTS

Pre-BDG hemodynamics differed only in that the mean pulmonary artery pressure was higher in group 2 (17.0 +/- 4.4 mm Hg) than in group 1 (13.8 +/- 4.5 mm Hg; p = 0.03). There were no differences between groups 1 and 2 in BDG outcome variables. At pre-Fontan catheterization, group 1 had higher mean pulmonary artery pressure (13.3 versus 10.9 mm Hg, p = 0.01), arterial oxygen saturation (85.8 versus 80.9%, p = 0.0001), and fewer collateral vessels were coil embolized than in group 2 (0.9 versus 1.6, p = 0.02). Mean ventricular end-diastolic pressure was similar between groups. The Nakata index in group 1 remained stable from pre-BDG to pre-Fontan (348 versus 391, p = 0.24), but it decreased in group 2 (375 versus 227, p = 0.046).

CONCLUSIONS

Patients with anterograde pulmonary blood flow after BDG had a modest increase in pulmonary artery growth and arterial oxygen saturations, and decreased collateral vessel formation. This did not, however, confer additional benefit on outcome after BDG or on eventual Fontan completion.

The impact of altitude on early outcome following the Fontan operation

BACKGROUND

The success of a Fontan circulation depends on several factors including low pulmonary vascular resistance. Pulmonary vascular resistance rises in response to hypoxia. Hypoxia is associated with altitude. Therefore, we wondered whether altitude is a risk factor for early failure after the Fontan operation. The aim was to test this hypothesis.

METHODS

Data were obtained from all published series of 'total cavopulmonary' Fontan operations since 1990. The early failure rate from each series and the altitude of the respective cities were recorded. Early failure was defined as death, takedown of Fontan, or transplantation during the same hospital admission. The association between altitude and failure rate was investigated by rank correlation and logistic regression.

RESULTS

24 series were identified from centres situated at altitudes ranging from sea level to 520 metres. The plot of failure rate versus altitude suggests that failure rate increases with altitude. Logistic regression did not fit the data adequately. This was possibly due to the influence of unmeasured and unknown factors affecting the results, as well as the fact that centres were not randomly chosen but were self-selected by virtue of publishing their results. However, Spearman's rank correlation was 0.74 (p = 0.001).

CONCLUSION

The early outcome of the Fontan circulation appears to be adversely affected by altitude.

Appropriate additional pulmonary blood flow at the bidirectional Glenn procedure is useful for completion of total cavopulmonary connection

BACKGROUND

The role and effect of additional pulmonary blood flow at the time of bidirectional Glenn procedure (BDG) is controversial. We assessed our experiences to clarify the effects of controlled additional pulmonary blood flow on outcomes after BDG.

METHODS

Thirty-eight patients who underwent BDG (2.1 +/- 2.1 years of age) were enrolled in this study. In group A (n = 29) additional pulmonary blood flow was controlled by the banding of the pulmonary trunk, or the previously created Blalock-Taussig shunt, to keep the central venous pressure equal to or less than 16 mm Hg at BDG. In group B (n = 9), BDG was the only source of pulmonary blood flow.

RESULTS

One operative death occurred in group B. In group A, 24 patients underwent total cavopulmonary connection (TCPC) 14 +/- 6 months after BDG, and the remaining 5 patients are waiting for TCPC in good condition. In group B, 6 patients underwent TCPC 8 +/- 7 months after BDG. One patient is awaiting TCPC and the remaining patient is considered unsuitable for TCPC. Cardiac catheterization performed in 32 patients showed significant decrease of pulmonary artery (Nakata) index from 307 +/- 73 to 215 +/- 45 mm2/m2 after BDG in group B (p < 0.05). On the other hand, the Nakata index stayed in higher range from 316 +/- 115 to 287 +/- 74 mm2/m2 in group A, and there was a significant correlation between the Nakata index and the percentage of its difference (Y = 40.823 - 0.144 X; n = 26, R = 0.740, p < 0.0001).

CONCLUSIONS

Appropriate additional pulmonary blood flow is useful for the completion of TCPC by means of suppressing the decrease in the size of the pulmonary artery, especially in patients with underdeveloped pulmonary arteries.

Perioperative management of patients with poorly functioning ventricles in the setting of the functionally univentricular heart

The patient with a functionally univentricular heart is at increased risk for ventricular dysfunction for a variety of reasons. At birth, the pulmonary and systemic circulations are in parallel, leading to pulmonary overcirculation and a volume-loaded functional ventricle. Significant atrioventricular valvar regurgitation, abnormal ventriculoarterial coupling, diastolic dysfunction, and altered ventricular geometry can also contribute to long-term ventricular dysfunction. These collected circumstances place the patient at increased risk for perioperative morbidity and mortality. We will discuss in this review the pathophysiology that leads to ventricular dysfunction at each stage of surgical palliation, as well as the strategies for perioperative management. In addition, we will highlight novel strategies for management of ventricular dysfunction.

Single-ventricle palliation for high-risk neonates: the emergence of an alternative hybrid stage I strategy

BACKGROUND

Survival after stage I palliation for hypoplastic left heart syndrome or related anomalies remains poor in high-risk neonates. We hypothesized that a less invasive hybrid approach would be beneficial in this patient population.

METHODS

The hybrid stage I procedure was performed in the catheterization laboratory. Via a median sternotomy, both branch pulmonary arteries were banded, and a ductal stent was delivered via a main pulmonary artery puncture and positioned under fluoroscopic guidance.

RESULTS

Between October 2003 and June 2005, 14 high-risk neonates underwent a hybrid stage I procedure. Eleven of 14 had hypoplastic left heart syndrome. Two also underwent peratrial atrial septal stenting, and 5 required percutaneous atrial stenting later. Two neonates with an intact or highly restrictive atrial septum had emergency percutaneous atrial stent placement. Hospital survival was 11 (78.5%) of 14. One patient required extracorporeal membrane oxygenation support for intraoperative cardiac arrest. He underwent cardiac transplantation but died later of sepsis. One patient died of ductal stent embolization, and a third died of progressive cardiac dysfunction. The first 4 patients required pulmonary artery band revisions. There were none after we modified our technique and added branch pulmonary artery angiograms. There were 2 interstage deaths from atrial stent occlusion and from preductal retrograde coarctation. Eight patients underwent stage II procedures, consisting of aortic arch reconstruction, atrial septectomy, and cavopulmonary shunt. Two patients died after stage II. One patient is awaiting stage II.

CONCLUSIONS

The hybrid stage I palliation is a valid option in high-risk neonates. As experience is accrued, it may become the preferred alternative. However, in aortic atresia, the development of preductal retrograde coarctation is a significant problem.

Midterm ventricular performance after Norwood procedure with right ventricular-pulmonary artery conduit

BACKGROUND

Midterm and long-term results of patients who underwent a Norwood procedure with a right ventricular-pulmonary artery conduit remain unclear. This study aimed to compare the midterm ventricular performance of the Norwood procedure with right ventricular-pulmonary artery conduit and the Norwood procedure with systemic-pulmonary shunt.

METHODS

Twenty-one patients who underwent both a bidirectional Glenn procedure and a total cavopulmonary connection after Norwood palliation at Fukuoka Children's Hospital Medical Center were divided into two groups: the systemic-pulmonary shunt group (n = 11) and the right ventricular-pulmonary artery conduit group (n = 10). End-systolic elastance (contractility), effective arterial elastance (afterload), and ventriculoarterial coupling and the ratio of stroke work and pressure-volume area (ventricular efficiency) were measured on the basis of cardiac catheterization data before the bidirectional Glenn procedure, before and after the total cavopulmonary connection, and at approximately 1 year after total cavopulmonary connection.

RESULTS

After bidirectional Glenn procedure and total cavopulmonary connection, end-systolic elastance of the right ventricular-pulmonary artery conduit group was lower than that of the systemic-pulmonary shunt group, whereas effective arterial elastance of the right ventricular-pulmonary artery conduit group was lower than that of the systemic-pulmonary shunt group. Consequently, there was no difference in ventricular efficiency in both groups 1 year after total cavopulmonary connection.

CONCLUSIONS

The midterm ventricular performance of the right ventricular-pulmonary artery conduit group was comparable with the systemic-pulmonary shunt group in terms of ventricular efficiency. However, after bidirectional Glenn procedure and total cavopulmonary connection, contractility in patients who underwent a Norwood procedure with a right ventricular-pulmonary artery conduit was inferior to that of patients who underwent a Norwood procedure with a systemic-pulmonary shunt.

Left ventricular performance of pulmonary atresia with intact ventricular septum after right heart bypass surgery

OBJECTIVE

The left ventricular performance in patients with pulmonary atresia with intact ventricular septum who were Fontan candidates before and after the bidirectional Glenn procedure and a staged total cavopulmonary connection was compared with that in patients with tricuspid atresia.

METHODS

Contractility (end-systolic elastance), afterload (effective arterial elastance), and ventricular efficiency (ventriculoarterial coupling, arterial elastance/end-systolic elastance ratio), and the ratio of stroke work and pressure-volume area were approximated on the basis of cardiac catheterization data before the bidirectional Glenn procedure, before and after staged total cavopulmonary connection, and approximately 1 year after the completion of total cavopulmonary connection in 20 patients with pulmonary atresia with intact ventricular septum and 21 patients with tricuspid atresia.

RESULTS

The end-systolic elastance of the pulmonary atresia with intact ventricular septum group was significantly inferior to that of the tricuspid atresia group after bidirectional Glenn procedure and total cavopulmonary connection (1 year after total cavopulmonary connection 1.85 +/- 0.51 mm Hg . m 2 . mL -1 vs 2.84 +/- 0.96 mm Hg . m 2 . mL -1 , P < .01). The arterial elastance was not different between groups throughout the assessment period and tended to increase in a stepwise fashion after bidirectional Glenn procedure and total cavopulmonary connection. The arterial elastance/end-systolic elastance ratio and ratio of stroke work and pressure-volume area of the pulmonary atresia with intact ventricular septum group tended to worsen, whereas those of the tricuspid atresia group tended to improve. The difference reached statistical significance 1 year after total cavopulmonary connection (1.15 +/- 0.35 vs 0.82 +/- 0.23 and 64.2% +/- 6.7% vs 71.3% +/- 5.7%, respectively, P < .05 and P < .05, respectively).

CONCLUSION

The contractility and ventricular efficiency of patients with pulmonary atresia with intact ventricular septum are inferior to those of patients with tricuspid atresia after bidirectional Glenn procedure and total cavopulmonary connection. A high-pressure residual right ventricle may impair the left ventricular performance of patients with pulmonary atresia with intact ventricular septum after bidirectional Glenn procedure and total cavopulmonary connection.

Ventricular mechanics in the bidirectional glenn procedure and total cavopulmonary connection

BACKGROUND

The time course of ventricular efficiency in Fontan candidates who underwent both the bidirectional Glenn procedure (BDG) and total cavopulmonary connection (TCPC) were analyzed in this study. We previously reported that volume-load reduction of BDG preceding TCPC allowed for any afterload mismatch to be corrected, thereby improving ventricular efficiency after staged TCPC.

METHODS

We measured percent normal systemic ventricular end-diastolic volume (%N-EDV), contractility (end-systolic elastance [Ees]), afterload (effective arterial elastance [Ea]), and ventricular efficiency (ventriculoarterial coupling [Ea/Ees]) based on cardiac catheterization data before and after both BDG and staged TCPC in 30 patients. Ees and Ea were approximated as follows: Ees = mean arterial pressure/minimal ventricular volume, and Ea = maximal ventricular pressure/(maximal ventricular volume - minimal ventricular volume), and Ea/Ees was then calculated. Ventricular volume was divided by body surface area.

RESULTS

The %N-EDV decreased both after BDG and after staged TCPC, thus resulting in an improvement of Ees. Although Ea increased both after BDG and after staged TCPC, Ea decreased during the interval between BDG and staged TCPC. These changes resulted in an improvement in Ea/Ees during the interval period and after staged TCPC, although Ea/Ees worsened after BDG.

CONCLUSIONS

Correction of afterload mismatch during the interval period between BDG and staged TCPC is considered to be one of the most important factors for obtaining excellent clinical results when selecting a staged strategy to treat high-risk Fontan candidates.

Ventricular energetics after the Fontan operation: contractility-afterload mismatch

OBJECTIVE

Fontan-type operations offer the opportunity to create pulmonary and systemic circulation in series with a single pumping chamber. The effectiveness of such a circulatory pattern determines resting and exercise hemodynamics in these patients. The present study investigated cardiac performance after the Fontan operation by using ventricular-vascular coupling framework analysis.

METHODS

In 12 anesthetized open-chest dogs, Fontan circulation was established by using a cavopulmonary anastomosis. Left ventricular hemodynamic variables were measured by using a combined pressure-volume-conductance catheter. Additionally, aortic flow and pressure were recorded continuously. Ventricular contractility was quantified by using the load-independent slope of the end-systolic pressure-volume relationship. Arterial system properties were quantified by using the end-systolic pressure/stroke volume ratio. The coupling between the left ventricle and arterial system was expressed by using the ratio of end-systolic pressure/stroke volume to slope of the end-systolic pressure-volume relationship. Additionally, external stroke work, total mechanical energy and mechanical efficiency (Mechanical efficiency = Stroke work/Total mechanical energy) were calculated. Impedance spectra were determined by means of Fourier analysis.

RESULTS

During Fontan circulation, the slope of the end-systolic pressure-volume relationship (5.3 +/- 0.6 vs 7.5 +/- 0.6 mm Hg/mL, P <.05) decreased, and the end-systolic pressure-stroke volume relationship (4.2 +/- 0.7 vs 3.3 +/- 0.5 mm Hg/mL, P =.23) increased with parallel increased characteristic impedance. Furthermore, the end-systolic pressure-stroke volume/slope of the end-systolic pressure-volume relationship ratio increased significantly (0.76 +/- 0.04 vs 0.42 +/- 0.03, P <.005). Simultaneously, stroke work (1846 +/- 146 vs 1389 +/- 60 mm Hg/mL, P <.05) and mechanical efficiency (0.82 +/- 0.09 vs 0.56 +/- 0.05, P <.05) were significantly reduced.

CONCLUSIONS

Fontan circulation leads to contractility-afterload mismatch by means of increased impedance caused by additional connection of the pulmonary vascular bed to the systemic vasculature and by means of deterioration of myocardial contractility. The increased ventriculoarterial coupling ratio and reduced mechanical efficiency predict limited cardiac functional reserve after the Fontan operation.

Ventricular energetics in endoventricular circular patch plasty for dyskinetic anterior left ventricular aneurysm

BACKGROUND

The endoventricular circular patch plasty (Dor procedure) applies to patients with a left ventricular dysfunction due to an ischemic dilated ventricle. In the present study, we analyzed left ventricular energetics in patients who underwent the Dor procedure.

METHODS

We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on the cardiac catheterization data before and after the Dor procedure in 8 patients with a postinfarction dyskinetic anterior left ventricular aneurysm. Concomitant procedures included coronary artery bypass grafting in all patients, mitral valve repair in one patient, and cryoablation in one patient. End-systolic elastance (Ees) and Ea were approximated as follows: Ees = mean arterial pressure/minimal left ventricular volume, and Ea = maximal left ventricular pressure/(maximal left ventricular volume-minimal left ventricular volume), and thereafter Ea/Ees and SW/PVA were calculated. The left ventricular volume was normalized with the body surface area.

RESULTS

End-systolic elastance (Ees) increased after the Dor procedure (from 1.15 +/- 0.60 to 1.86 +/- 0.84 mm Hg x m2 x mL(-1), p < 0.01), thus resulting in an improvement in Ea/Ees and SW/PVA (from 2.94 +/- 1.11 to 1.64 +/- 0.49, p < 0.01, and from 0.426 +/- 0.110 to 0.559 +/- 0.082, p < 0.01, respectively), even though Ea did not substantially change (from 2.96 +/- 0.78 to 2.74 +/- 0.55 mm Hg x m2 x mL(-1), p = 0.4).

CONCLUSIONS

Left ventricular contractility and efficiency improves after the Dor procedure in patients with a dyskinetic anterior left ventricular aneurysm. However, afterload does not change. The use of appropriate afterload-reducing therapy thus plays an especially important role in the management of patients who undergo the Dor procedure.

Evolution of staged approach for Fontan operation

BACKGROUND

During the early development of the Fontan operation, a number of physiologic and anatomical limits were proposed as selection criteria, and two criteria, pulmonary vascular resistance and ventricular function, have been important in predicting surgical outcome. The use of the bidirectional cavo pulmonary shunt as a staging procedure performed to control the pulmonary blood flow adequately and reduce ventricular volume over load has resulted in marked improvements in the early and late Fontan procedure results.

METHODS AND RESULTS

At our hospital we perform systemic pulmonary shunt or pulmonary artery banding in patients if pulmonary blood flow can not be controlled adequately in the neonatal period and then perform bidirectional cavo pulmonary shunt six months afterwards. During this operation we also performed simultaneous surgical repair for pulmonary artery distortion, anomalies of pulmonary venous connection, restriction of bulboventricular foramen and atrioventricular valve regurgitation. To determine the efficacy of this staged approach in avoiding increases in pulmonary vascular resistance and impaired ventricular function, surgical results were investigated. From February 1995 to May 2001, eighteen patients with cardiac morphology unsuitable for biventricular repair were admitted to our hospital. Twenty-six palliative procedures, were performed including seven pulmonary artery banding, three systemic pulmonary shunt, thirteen bidirectional cavo pulmonary shunt, one original Glenn procedure, four repair of coarctation of the aorta, two total anomalous pulmonary venous connection repair, one mitral valve plasty, and two patients required Damus-Kaye-Stansel procedure to release restrictive bulboventricular foramen. Fifteen patients underwent a modified Fontan operation (total cavopulmonary connection) after these palliative procedures. The operative mortality rate for these palliative procedures was 3.8% (1/26). The operative mortality rate for Fontan operation was 7.1% (1/14). Three patients awaiting the Fontan operation were considered good candidates for a final operation and no patients in this series were considered unsuitable for Fontan completion.

CONCLUSION

Our strategy of staged approach for Fontan procedure offers a good prognosis.

Cardioprotective effect of ischemic preconditioning on global myocardial ischemia in a sheep right heart bypass model

OBJECTIVES

Ischemic preconditioning has been used to induce the myocardium to adapt to ischemic stress preceded by short periods of ischemia and reperfusion. We used a sheep right heart bypass model with a conductance catheter to assess the cardioprotective effect of ischemic preconditioning on 30-minute normothermic global myocardial ischemia.

METHODS

Ischemic preconditioning was conducted in 6 sheep in 35-minute aortic cross-clampings interspersed with 5 minutes of reperfusion during cardiopulmonary bypass, with 6 sheep as time-matched controls. Global myocardial ischemia was subsequently achieved in 30-minute aortic cross-clamping with left ventricular unloading during normothermic cardiopulmonary bypass. Weaning from cardiopulmonary bypass was conducted 40 minutes after reperfusion. Before ischemia and 40, 70, and 100 minutes after reperfusion, left ventricular pressure-volume loops were measured using a conductance catheter during right heart bypass preparation. Left ventricular contractility, diastolic function, and mechanical efficiency were then evaluated. Right heart bypass was instituted to control the preload and to decompress the right ventricle completely, thereby eliminating parallel conductance variation.

RESULTS

No differences in the studied parameters were seen between ischemic-preconditioning and control groups before ischemia. Left ventricular contractility, diastolic function, and mechanical efficiency in the ischemic-preconditioning group were significantly superior to those in the control group after reperfusion.

CONCLUSIONS

Ischemic preconditioning attenuates postischemic myocardial dysfunction in a sheep model using 30-minute unloaded normothermic global myocardial ischemia. Ischemic preconditioning would thus be clinically significant when the ischemic damage is severe.

Effect of phosphodiesterase III inhibitor on contractility, afterload, and vascular capacitance during right heart bypass preparation

OBJECTIVES

Phosphodiesterase III inhibitors, which have both positive inotropic and vasodilatory effects, occasionally cause hypotension due to afterload reduction and possibly due to preload reduction caused by the increase in vascular capacitance.

METHODS

Six open-chest adult mongrel dogs were used to compare the effects on left ventricular contractility, afterload, and vascular capacitance of the phosphodiesterase III inhibitor, olprinone, with those of dobutamine using a right-heart-bypass model. Contractility and afterload were evaluated by the left ventricular pressure-volume relations with the use of a conductance catheter to derive the end-systolic elastance (Ees) and the effective arterial elastance (Ea). Vascular capacitance change was evaluated by reservoir volume change under a constant bypass flow (80 ml/kg per minute).

RESULTS

Ees increased significantly both with dobutamine (7.6 +/- 2.8 to 14.3 +/- 4.8 mmHg/ml, p < 0.05) and with olprinone (7.6 +/- 2.9 to 11.5 +/- 4.2 mmHg/ml, p < 0.05). Ea did not change with dobutamine (14.4 +/- 3.5 to 14.5 +/- 3.6 mmHg/ml, p = 0.9), whereas it decreased with olprinone (14.0 +/- 4.1 to 11.4 +/- 3.8 mmHg/ml, p = 0.093). Reservoir volume increased after the infusion of dobutamine (-94.0 +/- 39.8 ml), and decreased after the infusion of olprinone (-114.0 +/- 62.3 ml). The difference was statistically significant (p = 0.007). The reservoir volume change indicated that vascular capacitance decreased with dobutamine, and increased with olprinone.

CONCLUSIONS

Pre- and afterload reduction of olprinone combined with the positive inotropic effect are useful in treating congestive heart failure and managing low cardiac output syndrome after cardiac surgery.