S u r g i c a l D e v i c e T h e r a p y fo r H e a r t Fa i l u re i n t h e A d u l t w i t h Congenital Heart Disease Venkatachalam Mulukutla, MDa,*, Wayne J. Franklin, MDa,*, Chet R. Villa, MDb, David Luís Simón Morales, MDc KEYWORDS Adult congenital heart disease Ventricular assist device Heart failure Systemic right ventricle
KEY POINTS Individuals with congenital heart disease (CHD) are at a great risk for heart failure, and the underlying anatomic features are important predictors of heart failure. As the adult with CHD (ACHD) population grows older, multiple events, including years of an altered physiology, the neurohormonal cascade, and many still unknown, culminate in ventricular failure. As the ACHD population continues to grow in number and complexity, those with systemic right ventricle or single ventricle are at an increased risk of ventricular failure following surgical palliation. Ventricular assist devices have been used with success in bridging ACHD patients to heart transplantation or destination therapy. As the ACHD population continues to increase and technological advancement continues, surgical devices will play a significant role in the future.
multiple events, including years of an altered physiology, the neurohormonal cascade, and many still unknown, culminate in ventricular failure. Surgical device therapy is an effective method in supporting patients with heart failure.
INCIDENCE OF HEART FAILURE IN ADULTS WITH CONGENITAL HEART DISEASE Adults with CHD have a myriad of primary underlying conditions: tetralogy of Fallot, Ebstein anomaly, single right or left ventricles palliated with a Fontan procedure, or systemic right ventricle anatomy resulting from congenitally corrected transposition of the great arteries (CC-TGA) or D-transposition of the great arteries (D-TGA) after atrial switch
a Texas Children’s Hospital, Pediatric Cardiology, 6621 Fannin Street, Houston, TX 77030, USA; b Cincinnati Children’s Hospital Medical Center, Pediatric Cardiology, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; c Cincinnati Children’s Hospital Medical Center, Cardiovascular Surgery, 3333 Burnet Avenue, Cincinnati, OH 45229, USA * Corresponding authors. E-mail addresses: [email protected]; [email protected]
Heart Failure Clin 10 (2014) 197–206 http://dx.doi.org/10.1016/j.hfc.2013.09.016 1551-7136/14/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved.
heartfailure.theclinics.com
Congenital heart disease (CHD) has an incidence of approximately 8 per 1000 live births. Fifty years ago only 25% of infants with complex CHD survived beyond their first year of life, but today more than 95% will survive to adulthood.1 Approximately 15% of children born with CHD have potentially life-threatening defects, and many have complex lesions.2 With the advent of neonatal repair for complex lesions, modern surgical mortality rates are less than 5%.3 Today there are more than 1 million adults with CHD, outnumbering pediatric patients with CHD.4 Individuals with adult congenital heart disease (ACHD) are at a great risk for heart failure, and the underlying anatomic features are important predictors of heart failure. As the ACHD population grows older,
198
Mulukutla et al palliation. In addition, each surgical technique may have varied clinical outcomes depending on the era. The probability of heart failure in ACHD by congenital diagnosis is illustrated in Fig. 1. Patients with D-TGA born before the mid-1990s are likely to have undergone an atrial switch operation (described by Senning in 1959 and Mustard in 1964), leading to a systemic right ventricle. However, in the last 2 decades the arterial switch (first described by Jatene in 1983) has become the preferred surgical operation because it results in a systemic left ventricle. After follow-up of 15 to 18 years, there has been a documented decrease in the systemic right ventricular (RV) function in 32% to 48% of Mustard and Senning patients.5 Today, most patients with D-TGA undergo the arterial switch, and many are just now entering their second decade of life. In CC-TGA the right ventricle is the systemic ventricle, and many patients first present with clinical heart failure in adulthood. The anatomic variations are varied and can include pulmonic stenosis, ventricular septal defect, or tricuspid valve abnormalities. Systemic atrioventricular valve regurgitation may be a harbinger of heart failure, owing to worsening ventricular failure and RV volume overload. Two percent of patients per year can develop complete heart block. Presbitero and colleagues6 reported that 24% of the patients in the fifth decade of life had heart failure, increasing to 77% by the sixth decade of life. In study by Piran and colleagues,7 incidence of heart failure in patients with D-TGA subsequent to Mustard procedure was 22%, and 32% in patients with CC-TGA.
In patients born with a single ventricle, many historically underwent the classic atriopulmonary connection procedure, a modification of the approach described in 1971 for tricuspid atresia by Fontan and Baudet.8 The Fontan procedure, or total cavopulmonary connection, leaves the single-ventricle patient with abnormal venous circulation whereby the venal caval blood returns to the lung passively, with a subpulmonary ventricle. Today the Fontan operation has evolved to being a lateral tunnel through the right atrium, or an extracardiac conduit that connects directly to the branch pulmonary arteries. It is often the last surgical palliation in children born with a functional single ventricle. These patients can do well and survive into adulthood, but long-term follow up past the fifth or sixth decade is not known. In one study, 40% of patients who were palliated via a Fontan procedure developed systolic heart failure.7 Tetralogy of Fallot (TOF) is the most common cyanotic heart disease, for which Lillehei performed the first intracardiac repair in 1954. This procedure consisted of repair of a ventricular septal defect and resection of the infundibular region of the RV outflow tract.9 Today the repair minimizes ventricular incision and infundibular resection, and incorporates a transannular patch. The surgical intervention ultimately leads to distortion of pulmonary valve apparatus and pulmonary regurgitation, which is well tolerated for many years but has an effect on the RV size and function.3 Norozi and colleagues10 reported on 94 patients with TOF, of whom 44 had heart failure defined by a brain natriuretic peptide (BNP) level of greater than 100 pg/mL and a maximal oxygen uptake (VO2max) of less than 25 m/kg/min, although most were asymptomatic or minimally symptomatic, of New York Heart Association (NYHA) functional class I or II. Complications of progressive RV dilation include right heart failure with decreased exercise tolerance, atrial and ventricular arrhythmias, and sudden cardiac death. The lifetime incidence of sudden cardiac death is 8.8% in postoperative TOF patients in adulthood.1 Pulmonary valve replacement is considered the treatment of choice, and timing is still debated, with mitigating factors including exercise intolerance, ventricular arrhythmias, and/or RV dysfunction or dilation (RV enddiastolic volume >150 mL/m2).
NEUROHORMONAL ACTIVATION Fig. 1. Incidence of heart failure in adult congenital heart disease. TGA, transposition of the great arteries. (From Norozi K, Wessel A, Alpers V, et al. Incidence and risk distribution of heart failure in adolescents and adults with congenital heart disease after cardiac surgery. Am J Cardiol 2006;97(8):1238–43; with permission.)
Neurohormonal activation is an important factor in adults with heart failure. Data have shown that the degree of neurohormonal activation in adults with heart failure is correlated with functional capacity, left ventricular (LV) dysfunction, and mortality.
Surgical Device Therapy for HF in ACHD Study of heart failure in the ACHD population has shown similar findings. Bolger and colleagues11 showed an elevation in atrial natriuretic peptide (ANP), BNP, endothelin-1 (ET-1), and norepinephrine in the ACHD population with heart failure, as demonstrated in Fig. 2, and these correlate with NYHA class, ventricular function, and mortality.
PHARMACOLOGIC TREATMENT Treatment of adults with congestive heart failure attributable to acquired heart disease has been shown in large randomized controlled trials to be
effective in improving mortality. In one of the landmark studies involving angiotensin-converting enzyme (ACE) inhibition, CONSENSUS, patients with NYHA functional class III or IV heart failure and an LV ejection fraction of less than 35% were prescribed enalapril. Patients taking enalapril had a 12-month relative mortality reduction of 31% and a 10-year averaged mortality reduction of 30%.12 In a meta-analysis involving patients with LV ejection fraction of from less than 35% to 45%, all of whom were NYHA class II to IV, b-blockers decreased mortality by approximately 12% in 1 year and saved 3.8 lives in the first year
Fig. 2. Neurohormonal activation in adults with heart failure. ANOVA, analysis of variance; ANP, atrial natriuretic peptide; BNP, brain natriuretic peptide; ET-1, endothelin-1; NYHA, New York Heart Association. (From Bolger AP, Shama R, Li W, et al. Neurohormonal activation and the chronic heart failure syndrome in adults with congenital heart disease. Circulation 2001;106(1):92–9; with permission.)
199
200
Mulukutla et al per 100 patients treated.13 The RALES trial proved the benefit of an aldosterone agonist, spironolactone, in NYHA class III or IV heart failure. In the ACHD population, the data on the benefit of ACE inhibitors, b-blockers, and spironolactone are sparse. Most of the adult literature is pertinent to patients with ischemic heart disease and older patients, and the adult congenital population is much younger on average, has nonischemic cardiomyopathy, or a single ventricle. Similarly, relatively few studies exist for heart failure in pediatrics. Shaddy and colleagues14 reported, in a randomized control trial of carvedilol for children with heart failure, that there was no significant improvement in outcomes of clinical heart failure in children and adolescents with systolic heart failure. The study included both systemic right and left ventricles, and suggested that ventricular morphology might be an important factor in determining the effect of this medication. In the ACHD population, the authors often prescribe standard heart failure treatment with the hope that it may be effective. It is clear that despite treatment, many patients will develop heart failure. Complicating pharmacologic therapy is the high incidence of sick sinus syndrome and other conduction abnormalities in ACHD patients (especially for D-TGA after Senning or Mustard operation, single-ventricle patients after Fontan completion, and complete heart block CC-TGA). Janousek and colleagues15 reported that in 359 patients after Mustard or Senning operation, there was a prevalence of sinus node dysfunction of 51% at 2 years and 64% at 10 years postoperatively. Incidence of second-degree or third-degree block was 3.2%. In CC-TGA, the risk of heart block is 1% to 2% per year. Use of b-blockers in such a patient population requires close monitoring; the possibility of supraventricular tachyarrhythmia as a result can also be a concern.
DEVICE THERAPY Many adults with complex CHD have had surgeries that are not curative but palliative. In most cases, the literature includes anecdotal evidence and case reports of device therapy used in the ACHD population.
Balloon Pump The intra-aortic balloon pump (IABP) is a form of mechanical support that is placed via femoral arterial access in the descending aorta. The balloon expands during diastole to improve coronary perfusion and deflates during systole to improve forward flow, owing to lower systolic afterload. In the recent IABP-Shock II trial, there was no
significant reduction in 30-day mortality in patients with cardiogenic shock following acute myocardial infarction.16 There are few reports of IABP use in CHD. IABP has been used in the immediate postoperative period following completion of Fontan in 5 series with a total of 21 patients, with survival ranging from 0% to 100%.16 In one case report, a balloon pump was used in a 20-year-old patient with acute cardiogenic shock following a dualchamber epicardial lead placement for sinus node dysfunction. The balloon pump was placed in lieu of extracorporeal membrane oxygenation (ECMO) and was weaned off in 72 hours.17 Thus in specific situations, IABP may be effective for brief periods or before bridging to further support.
Impella (Abiomed) The Impella device (Abiomed, Danvers, MA) is a minimally invasive catheter-based assist device designed to directly unload the left ventricle and expel blood in the ascending aorta. At present there are two models, one that can pump 2.5 liters per minute and a second that can pump 5 liters per minute. In adults, the Impella 2.5 has been used in high-risk percutaneous coronary interventions and in patients with cardiogenic shock.18 In the setting of CHD, there is little reported use. The use of an Impella 2.5 and 5.0 was investigated in a mock circulatory system for a failing Fontan. In this model, the left-sided microaxial pumps were not well suited for cavopulmonary support because of severe recirculation.19
TandemHeart Percutaneous Ventricular Assist Device The TandemHeart (Cardiac Assist, Inc, Pittsburgh, PA) is a temporary cardiac assist device, with an external continuous-flow centrifugal pump placed percutaneously (peripheral ventricular assist device [VAD]). One inflow cannula is inserted across the intra-atrial septum into the left atrium, and the pump withdraws blood and propels it into another cannula in the femoral artery. The pump can deliver flow up to 5 liters per minute and may support patients for up 2 weeks. In the literature to date there are no case reports of its use in the ACHD population.
Berlin Heart EXCOR (Pediatric Ventricular Assist Device) Children with heart failure have limited options for mechanical circulatory support. Fraser and colleagues20 reported a statistically significant difference in mortality of children with heart failure when comparing the Berlin Heart device with ECMO. The EXCOR (Berlin Heart GmbH, Berlin,
Surgical Device Therapy for HF in ACHD Germany) pediatric VAD is a pneumatically driven pulsatile-flow mechanical circulatory support designed for children. As the progress in developing pediatric devices has been challenging because of size constraints, many options do not exist for these smaller patients.20 As a result, pediatric patients with CHD have been mainly placed on the Berlin Heart as a bridge to transplantation. Complications can include bleeding, stroke, and infection.
Left Ventricular Assist Devices According to the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) database, which was established in 2006, there have been more than 6000 adults with heart failure who have been given a left ventricular assist device (LVAD).21 Patients have received the mechanical circulatory device as a bridge to transplant, a bridge to recovery, or a destination therapy. An LVAD has two cannulas, an inflow cannula usually placed in the left ventricle and an outflow cannula placed in the ascending aorta. There are two categories of LVADs, a pulsatile pump or a continuous-flow pump.22 The continuous-flow devices use a centrifugal or axial flow pump and have a central rotor containing magnets. Electric current passes through the coils applying force to the magnets, which in turn cause the rotors to spin and the blood to be moved forward. In a randomized trial comparing devices, 134 patients underwent continuous flow and 66 patients pulsatile flow, and at 2 years there was a statistically significant difference in survival rates, at 58% (continuous flow) versus 24% (pulsatile
flow). There were also statistically significant differences favoring continuous-flow devices regarding infection risk, renal and respiratory failure, and the need for pump replacement.23 The continuous-flow devices are smaller and have proved to be more durable than their pulsatile counterparts.24 Today many devices exist, including the HeartMate I/II/III, Debakey MicroMed VAD, Jarvik 2000, and Berlin Heart EXCOR, among others. In most cases, the literature includes anecdotal evidence and case reports of device therapy used in the ACHD population (Tables 1 and 2). Use of LVADs in ACHD Systemic right ventricles (CC-TGA and D-TGA) In CC-TGA, the morphologic right ventricle is the systemic ventricle, and in D-TGA the morphologic right ventricle is the systemic ventricle after the Mustard or Senning operation. The first case report of LVAD use in D-TGA after a Mustard operation was in 1999.25 In 2 patients (1 CC-TGA and 1 D-TGA status post Senning) reported by Stewart and colleagues,26 both had LVAD implantation and both were placed intraperitoneally because of anatomic considerations. The operations resulted in midline abdominal wound dehiscence as a result of tension from placing the LVAD in a more medial position.26 With the advent of smaller axial flow assist devices the difficulties of wound dehiscence decreased, but the positioning of the VAD flow cannulas continues to be a challenge. In 2010, Joyce and colleagues27 reported placing 2 HeartMate II devices in 2 patients (35 and 33 years old old) with D-TGA, and a DeBakey VAD (MicroMed) in a
Table 1 Short-term mechanical circulatory support systems available in the United States Device (Manufacturer) ECMO (multiple manufacturers) RotaFlow (Maquet) PediMag (Thoratec) Tandem Heart pVAD (Cardiac Assist) Impella 2.5, 5.0 (Abiomed) IABP (Maquet) AB5000 (Abiomed) CentriMag (Thoratec) a
Minimum Patient Size
Anticoagulation Flow Rate Strategy (L/min)
Position
Pump Type
Extracorporeal
Centrifugal or roller pump Centrifugal Centrifugal Centrifugal
No minimum Heparin
Variable
No minimum Heparin 1.3 m2
1.7 m2b (CardioWest)
PVAD/IVAD (Thoratec)
Heartware HVAD (Heartware) HeartMate II (Thoratec) Jarvik 2000 (Jarvik Heart)
Pericardial
Continuous >1.2 m2
Preperitoneal pocket Left ventricle
Continuous >1.3 m2 Continuous >1.2 m2
Flow Rate (L/min)
Warfarin and ASA/ Variablea dipyridamole Warfarin and ASA/
KEY POINTS Individuals with congenital heart disease (CHD) are at a great risk for heart failure, and the underlying anatomic features are important predictors of heart failure. As the adult with CHD (ACHD) population grows older, multiple events, including years of an altered physiology, the neurohormonal cascade, and many still unknown, culminate in ventricular failure. As the ACHD population continues to grow in number and complexity, those with systemic right ventricle or single ventricle are at an increased risk of ventricular failure following surgical palliation. Ventricular assist devices have been used with success in bridging ACHD patients to heart transplantation or destination therapy. As the ACHD population continues to increase and technological advancement continues, surgical devices will play a significant role in the future.
multiple events, including years of an altered physiology, the neurohormonal cascade, and many still unknown, culminate in ventricular failure. Surgical device therapy is an effective method in supporting patients with heart failure.
INCIDENCE OF HEART FAILURE IN ADULTS WITH CONGENITAL HEART DISEASE Adults with CHD have a myriad of primary underlying conditions: tetralogy of Fallot, Ebstein anomaly, single right or left ventricles palliated with a Fontan procedure, or systemic right ventricle anatomy resulting from congenitally corrected transposition of the great arteries (CC-TGA) or D-transposition of the great arteries (D-TGA) after atrial switch
a Texas Children’s Hospital, Pediatric Cardiology, 6621 Fannin Street, Houston, TX 77030, USA; b Cincinnati Children’s Hospital Medical Center, Pediatric Cardiology, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; c Cincinnati Children’s Hospital Medical Center, Cardiovascular Surgery, 3333 Burnet Avenue, Cincinnati, OH 45229, USA * Corresponding authors. E-mail addresses: [email protected]; [email protected]
Heart Failure Clin 10 (2014) 197–206 http://dx.doi.org/10.1016/j.hfc.2013.09.016 1551-7136/14/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved.
heartfailure.theclinics.com
Congenital heart disease (CHD) has an incidence of approximately 8 per 1000 live births. Fifty years ago only 25% of infants with complex CHD survived beyond their first year of life, but today more than 95% will survive to adulthood.1 Approximately 15% of children born with CHD have potentially life-threatening defects, and many have complex lesions.2 With the advent of neonatal repair for complex lesions, modern surgical mortality rates are less than 5%.3 Today there are more than 1 million adults with CHD, outnumbering pediatric patients with CHD.4 Individuals with adult congenital heart disease (ACHD) are at a great risk for heart failure, and the underlying anatomic features are important predictors of heart failure. As the ACHD population grows older,
198
Mulukutla et al palliation. In addition, each surgical technique may have varied clinical outcomes depending on the era. The probability of heart failure in ACHD by congenital diagnosis is illustrated in Fig. 1. Patients with D-TGA born before the mid-1990s are likely to have undergone an atrial switch operation (described by Senning in 1959 and Mustard in 1964), leading to a systemic right ventricle. However, in the last 2 decades the arterial switch (first described by Jatene in 1983) has become the preferred surgical operation because it results in a systemic left ventricle. After follow-up of 15 to 18 years, there has been a documented decrease in the systemic right ventricular (RV) function in 32% to 48% of Mustard and Senning patients.5 Today, most patients with D-TGA undergo the arterial switch, and many are just now entering their second decade of life. In CC-TGA the right ventricle is the systemic ventricle, and many patients first present with clinical heart failure in adulthood. The anatomic variations are varied and can include pulmonic stenosis, ventricular septal defect, or tricuspid valve abnormalities. Systemic atrioventricular valve regurgitation may be a harbinger of heart failure, owing to worsening ventricular failure and RV volume overload. Two percent of patients per year can develop complete heart block. Presbitero and colleagues6 reported that 24% of the patients in the fifth decade of life had heart failure, increasing to 77% by the sixth decade of life. In study by Piran and colleagues,7 incidence of heart failure in patients with D-TGA subsequent to Mustard procedure was 22%, and 32% in patients with CC-TGA.
In patients born with a single ventricle, many historically underwent the classic atriopulmonary connection procedure, a modification of the approach described in 1971 for tricuspid atresia by Fontan and Baudet.8 The Fontan procedure, or total cavopulmonary connection, leaves the single-ventricle patient with abnormal venous circulation whereby the venal caval blood returns to the lung passively, with a subpulmonary ventricle. Today the Fontan operation has evolved to being a lateral tunnel through the right atrium, or an extracardiac conduit that connects directly to the branch pulmonary arteries. It is often the last surgical palliation in children born with a functional single ventricle. These patients can do well and survive into adulthood, but long-term follow up past the fifth or sixth decade is not known. In one study, 40% of patients who were palliated via a Fontan procedure developed systolic heart failure.7 Tetralogy of Fallot (TOF) is the most common cyanotic heart disease, for which Lillehei performed the first intracardiac repair in 1954. This procedure consisted of repair of a ventricular septal defect and resection of the infundibular region of the RV outflow tract.9 Today the repair minimizes ventricular incision and infundibular resection, and incorporates a transannular patch. The surgical intervention ultimately leads to distortion of pulmonary valve apparatus and pulmonary regurgitation, which is well tolerated for many years but has an effect on the RV size and function.3 Norozi and colleagues10 reported on 94 patients with TOF, of whom 44 had heart failure defined by a brain natriuretic peptide (BNP) level of greater than 100 pg/mL and a maximal oxygen uptake (VO2max) of less than 25 m/kg/min, although most were asymptomatic or minimally symptomatic, of New York Heart Association (NYHA) functional class I or II. Complications of progressive RV dilation include right heart failure with decreased exercise tolerance, atrial and ventricular arrhythmias, and sudden cardiac death. The lifetime incidence of sudden cardiac death is 8.8% in postoperative TOF patients in adulthood.1 Pulmonary valve replacement is considered the treatment of choice, and timing is still debated, with mitigating factors including exercise intolerance, ventricular arrhythmias, and/or RV dysfunction or dilation (RV enddiastolic volume >150 mL/m2).
NEUROHORMONAL ACTIVATION Fig. 1. Incidence of heart failure in adult congenital heart disease. TGA, transposition of the great arteries. (From Norozi K, Wessel A, Alpers V, et al. Incidence and risk distribution of heart failure in adolescents and adults with congenital heart disease after cardiac surgery. Am J Cardiol 2006;97(8):1238–43; with permission.)
Neurohormonal activation is an important factor in adults with heart failure. Data have shown that the degree of neurohormonal activation in adults with heart failure is correlated with functional capacity, left ventricular (LV) dysfunction, and mortality.
Surgical Device Therapy for HF in ACHD Study of heart failure in the ACHD population has shown similar findings. Bolger and colleagues11 showed an elevation in atrial natriuretic peptide (ANP), BNP, endothelin-1 (ET-1), and norepinephrine in the ACHD population with heart failure, as demonstrated in Fig. 2, and these correlate with NYHA class, ventricular function, and mortality.
PHARMACOLOGIC TREATMENT Treatment of adults with congestive heart failure attributable to acquired heart disease has been shown in large randomized controlled trials to be
effective in improving mortality. In one of the landmark studies involving angiotensin-converting enzyme (ACE) inhibition, CONSENSUS, patients with NYHA functional class III or IV heart failure and an LV ejection fraction of less than 35% were prescribed enalapril. Patients taking enalapril had a 12-month relative mortality reduction of 31% and a 10-year averaged mortality reduction of 30%.12 In a meta-analysis involving patients with LV ejection fraction of from less than 35% to 45%, all of whom were NYHA class II to IV, b-blockers decreased mortality by approximately 12% in 1 year and saved 3.8 lives in the first year
Fig. 2. Neurohormonal activation in adults with heart failure. ANOVA, analysis of variance; ANP, atrial natriuretic peptide; BNP, brain natriuretic peptide; ET-1, endothelin-1; NYHA, New York Heart Association. (From Bolger AP, Shama R, Li W, et al. Neurohormonal activation and the chronic heart failure syndrome in adults with congenital heart disease. Circulation 2001;106(1):92–9; with permission.)
199
200
Mulukutla et al per 100 patients treated.13 The RALES trial proved the benefit of an aldosterone agonist, spironolactone, in NYHA class III or IV heart failure. In the ACHD population, the data on the benefit of ACE inhibitors, b-blockers, and spironolactone are sparse. Most of the adult literature is pertinent to patients with ischemic heart disease and older patients, and the adult congenital population is much younger on average, has nonischemic cardiomyopathy, or a single ventricle. Similarly, relatively few studies exist for heart failure in pediatrics. Shaddy and colleagues14 reported, in a randomized control trial of carvedilol for children with heart failure, that there was no significant improvement in outcomes of clinical heart failure in children and adolescents with systolic heart failure. The study included both systemic right and left ventricles, and suggested that ventricular morphology might be an important factor in determining the effect of this medication. In the ACHD population, the authors often prescribe standard heart failure treatment with the hope that it may be effective. It is clear that despite treatment, many patients will develop heart failure. Complicating pharmacologic therapy is the high incidence of sick sinus syndrome and other conduction abnormalities in ACHD patients (especially for D-TGA after Senning or Mustard operation, single-ventricle patients after Fontan completion, and complete heart block CC-TGA). Janousek and colleagues15 reported that in 359 patients after Mustard or Senning operation, there was a prevalence of sinus node dysfunction of 51% at 2 years and 64% at 10 years postoperatively. Incidence of second-degree or third-degree block was 3.2%. In CC-TGA, the risk of heart block is 1% to 2% per year. Use of b-blockers in such a patient population requires close monitoring; the possibility of supraventricular tachyarrhythmia as a result can also be a concern.
DEVICE THERAPY Many adults with complex CHD have had surgeries that are not curative but palliative. In most cases, the literature includes anecdotal evidence and case reports of device therapy used in the ACHD population.
Balloon Pump The intra-aortic balloon pump (IABP) is a form of mechanical support that is placed via femoral arterial access in the descending aorta. The balloon expands during diastole to improve coronary perfusion and deflates during systole to improve forward flow, owing to lower systolic afterload. In the recent IABP-Shock II trial, there was no
significant reduction in 30-day mortality in patients with cardiogenic shock following acute myocardial infarction.16 There are few reports of IABP use in CHD. IABP has been used in the immediate postoperative period following completion of Fontan in 5 series with a total of 21 patients, with survival ranging from 0% to 100%.16 In one case report, a balloon pump was used in a 20-year-old patient with acute cardiogenic shock following a dualchamber epicardial lead placement for sinus node dysfunction. The balloon pump was placed in lieu of extracorporeal membrane oxygenation (ECMO) and was weaned off in 72 hours.17 Thus in specific situations, IABP may be effective for brief periods or before bridging to further support.
Impella (Abiomed) The Impella device (Abiomed, Danvers, MA) is a minimally invasive catheter-based assist device designed to directly unload the left ventricle and expel blood in the ascending aorta. At present there are two models, one that can pump 2.5 liters per minute and a second that can pump 5 liters per minute. In adults, the Impella 2.5 has been used in high-risk percutaneous coronary interventions and in patients with cardiogenic shock.18 In the setting of CHD, there is little reported use. The use of an Impella 2.5 and 5.0 was investigated in a mock circulatory system for a failing Fontan. In this model, the left-sided microaxial pumps were not well suited for cavopulmonary support because of severe recirculation.19
TandemHeart Percutaneous Ventricular Assist Device The TandemHeart (Cardiac Assist, Inc, Pittsburgh, PA) is a temporary cardiac assist device, with an external continuous-flow centrifugal pump placed percutaneously (peripheral ventricular assist device [VAD]). One inflow cannula is inserted across the intra-atrial septum into the left atrium, and the pump withdraws blood and propels it into another cannula in the femoral artery. The pump can deliver flow up to 5 liters per minute and may support patients for up 2 weeks. In the literature to date there are no case reports of its use in the ACHD population.
Berlin Heart EXCOR (Pediatric Ventricular Assist Device) Children with heart failure have limited options for mechanical circulatory support. Fraser and colleagues20 reported a statistically significant difference in mortality of children with heart failure when comparing the Berlin Heart device with ECMO. The EXCOR (Berlin Heart GmbH, Berlin,
Surgical Device Therapy for HF in ACHD Germany) pediatric VAD is a pneumatically driven pulsatile-flow mechanical circulatory support designed for children. As the progress in developing pediatric devices has been challenging because of size constraints, many options do not exist for these smaller patients.20 As a result, pediatric patients with CHD have been mainly placed on the Berlin Heart as a bridge to transplantation. Complications can include bleeding, stroke, and infection.
Left Ventricular Assist Devices According to the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) database, which was established in 2006, there have been more than 6000 adults with heart failure who have been given a left ventricular assist device (LVAD).21 Patients have received the mechanical circulatory device as a bridge to transplant, a bridge to recovery, or a destination therapy. An LVAD has two cannulas, an inflow cannula usually placed in the left ventricle and an outflow cannula placed in the ascending aorta. There are two categories of LVADs, a pulsatile pump or a continuous-flow pump.22 The continuous-flow devices use a centrifugal or axial flow pump and have a central rotor containing magnets. Electric current passes through the coils applying force to the magnets, which in turn cause the rotors to spin and the blood to be moved forward. In a randomized trial comparing devices, 134 patients underwent continuous flow and 66 patients pulsatile flow, and at 2 years there was a statistically significant difference in survival rates, at 58% (continuous flow) versus 24% (pulsatile
flow). There were also statistically significant differences favoring continuous-flow devices regarding infection risk, renal and respiratory failure, and the need for pump replacement.23 The continuous-flow devices are smaller and have proved to be more durable than their pulsatile counterparts.24 Today many devices exist, including the HeartMate I/II/III, Debakey MicroMed VAD, Jarvik 2000, and Berlin Heart EXCOR, among others. In most cases, the literature includes anecdotal evidence and case reports of device therapy used in the ACHD population (Tables 1 and 2). Use of LVADs in ACHD Systemic right ventricles (CC-TGA and D-TGA) In CC-TGA, the morphologic right ventricle is the systemic ventricle, and in D-TGA the morphologic right ventricle is the systemic ventricle after the Mustard or Senning operation. The first case report of LVAD use in D-TGA after a Mustard operation was in 1999.25 In 2 patients (1 CC-TGA and 1 D-TGA status post Senning) reported by Stewart and colleagues,26 both had LVAD implantation and both were placed intraperitoneally because of anatomic considerations. The operations resulted in midline abdominal wound dehiscence as a result of tension from placing the LVAD in a more medial position.26 With the advent of smaller axial flow assist devices the difficulties of wound dehiscence decreased, but the positioning of the VAD flow cannulas continues to be a challenge. In 2010, Joyce and colleagues27 reported placing 2 HeartMate II devices in 2 patients (35 and 33 years old old) with D-TGA, and a DeBakey VAD (MicroMed) in a
Table 1 Short-term mechanical circulatory support systems available in the United States Device (Manufacturer) ECMO (multiple manufacturers) RotaFlow (Maquet) PediMag (Thoratec) Tandem Heart pVAD (Cardiac Assist) Impella 2.5, 5.0 (Abiomed) IABP (Maquet) AB5000 (Abiomed) CentriMag (Thoratec) a
Minimum Patient Size
Anticoagulation Flow Rate Strategy (L/min)
Position
Pump Type
Extracorporeal
Centrifugal or roller pump Centrifugal Centrifugal Centrifugal
No minimum Heparin
Variable
No minimum Heparin 1.3 m2
1.7 m2b (CardioWest)
PVAD/IVAD (Thoratec)
Heartware HVAD (Heartware) HeartMate II (Thoratec) Jarvik 2000 (Jarvik Heart)
Pericardial
Continuous >1.2 m2
Preperitoneal pocket Left ventricle
Continuous >1.3 m2 Continuous >1.2 m2
Flow Rate (L/min)
Warfarin and ASA/ Variablea dipyridamole Warfarin and ASA/
