Some thoughts about the "lesser" ventricle in the "greater" circulation.
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Cardiac Surgical Procedures↗
Biomedical subjects
Robert M Freedom
Publications and source records attributed to Robert M Freedom.
Pulmonary atresia with intact ventricular septum: management of, and outcomes for, a cohort of 210 consecutive patients.
OBJECTIVES: We sought to determine trends, and outcomes, for a cohort of patients with pulmonary atresia with intact ventricular septum born between 1965 and 1998. BACKGROUND: Pulmonary atresia with intact ventricular septum is a complex lesion that remains a therapeutic challenge, particularly regarding the suitability for biventricular repair. METHODS: We identified 210 consecutive patients, and reviewed their medical records, initial angiograms, and echocardiograms, along with the relevant surgical and pathology reports. RESULTS: The mean initial Z-score for the diameter of the tricuspid valve was -0.99 +/- 1.95, with Ebstein's malformation in 8%. A right ventricular dependent coronary arterial circulation was found in 23%. The proportion of patients who received treatment increased over time, although placement of an arterial shunt was the predominant initial procedure throughout the experience. At the last follow-up, 107 patients had not reached the planned final stage of their repair, and 79% of these had died. Of the 103 reaching the final stage of planned repair, 58 had undergone attempted biventricular repair, with 34% dying; 14 had undergone attempted one and a half ventricular repair, with 7% dying, and 31 had undergone attempted functionally univentricular repair, with 10% dying. Overall, survival was 57% at the age of 1 year, 48% at 5 years, and 43% at 10 years. Survival improved over time, with survival of 75% at 1 year, and 67% at 5 years, for patients born between 1992 and 1998. An earlier date of birth, the presence of Ebstein's malformation, and prematurity were all significant independent factors associated with decreased survival. A greater severity of coronary arterial abnormalities was significantly associated with a greater likelihood of left ventricular dysfunction during follow-up. CONCLUSIONS: The outcomes for patients born with pulmonary atresia with intact ventricular septum have improved over time, albeit that careful initial management, and better selection, is still indicated for those planned to undergo biventricular repair.
Cardiac Surgical Procedures↗
Outcomes after balloon dilation of congenital aortic stenosis in children and adolescents.
OBJECTIVES: To determine the long-term outcomes and risk factors for, reintervention after balloon dilation of congenital aortic stenosis in children aged 6 months or older. BACKGROUND: Although balloon dilation of congenital aortic stenosis has become a primary therapeutic strategy, few data are available regarding long-term outcomes. METHODS: We carried out a retrospective review of 87 children who had undergone balloon dilation of the aortic valve at median age of 6.9 years. RESULTS: The procedure was completed in 98% of the children, with an average reduction in the gradient across the valve of 64 +/- 28%, and without mortality. Of the children, 76 had been followed for a mean of 6.3 +/- 4.2 years. Reintervention on the aortic valve was required in 32 children, with 12 undergoing reintervention within 6 months, with 1 death. Another patient had died over the period of follow-up due to a non-cardiac event. Estimated freedom from reintervention was 86% at 1 year, 67% at 5 years, and 46% at 12 years. Parametric modeling of the hazard function showed a brief early phase of increased risk, superimposed on an ongoing constant risk. The only incremental risk factor for the early phase was a residual gradient immediately subsequent to the procedure greater than 30 mmHg. Incremental risk factors for the constant phase included the presence of symmetric valvar opening, and greater than moderate regurgitation immediately after dilation. CONCLUSION: Long-term survival was excellent, albeit that the need for further reintervention was high due to the palliative nature of the procedure.
Adolescent↗
The biological "scrabble" of pulmonary arteriovenous malformations: considerations in the setting of cavopulmonary surgery.
Pulmonary arteriovenous fistulas are vascular malformations, which, by virtue of producing abnormal vascular connections proximal to the units of gas exchange, result in intrapulmonary right-to-left shunting. These malformations or fistulas reflect at least in part disordered angiogenesis, and less commonly recruitment and dilation of pre-existing vascular channels. Pulmonary arteriovenous fistulas occur in a number of diverse clinical settings. Such fistulas are a well-established feature of the Weber-Osler-Rendu complex, or hereditary haemorrhagic telangiectasia, an autosomal dominant vascular dysplasia characterized by mucocutaneous telangiectasis, epistaxis, gastrointestinal haemorrhage, and arteriovenous malformations in the lung, brain, liver and elsewhere. They are also seen in the patient with acute or chronic liver disease, disease that is usually but not invariably severe, or those with non-cirrhotic portal hypertension. They may occur as congenital malformations, single or diffuse, large or small in isolation, and when large or extensive enough may result in hypoxaemia, clinical cyanosis, and heart failure. Cerebral vascular accidents are also a well-known complication of this disorder. An extensive literature has accumulated with regard to the pulmonary arteriovenous fistulas seen in the setting of the Weber-Osler-Rendu complex, and there is considerable information on the genetics, basic biology, clinical findings, complications and therapeutic interventions of these malformations in the setting of this syndrome. These issues, however, are not the primary considerations of this review, although some aspects of this fascinating disorder will be discussed later. Rather the focus will be on pulmonary arteriovenous malformations that develop in the setting of cavopulmonary surgery, and their relationship to the pulmonary arteriovenous fistulas occurring in the hepatopulmonary syndrome. The complex tapestry of these overlapping and intersecting clinical observations will be unfolded in the light of their chronology.
Angiography↗
Outcomes for patients with an aortopulmonary window, and the impact of associated cardiovascular lesions.
An aortopulmonary window is a communication between the ascending aorta and pulmonary trunk in the presence of two separate arterial valves, and is often complicated by other associated defects. We sought to determine management and related outcomes in patients with this malformation. We identified those patients presenting between 1969 and 1999 from the databases held in our Departments of Cardiology, Pathology and Cardiovascular Surgery. We obtained data relating to issues concerning demography, clinical findings, imaging, management and outcome. The median age at presentation for the 42 patients identified, of whom 23 were female, was 62 days, with a range from birth to 6 years. Associated cardiac defects were present in 34 patients, including interruption of the aortic arch in 6 patients. The correct diagnosis was initially missed in 13 patients. Of the patients, six died without surgical repair, and 1 patient was lost-to-follow-up. Repair was performed in 35 patients, subsequent to repair of other defects in 4, in association with repair of other defects in 17, of whom 3 died, and as an isolated procedure in 14 patients, one of the latter being treated by transcatheter closure. Overall, there were 9 deaths, all in patients with complex associated defects, except 1 patient with a missed aortopulmonary window after repair of aortic coarctation. Kaplan-Meier estimates of survival were 81% at 3 months until 11.5 years, and 69% up to 21 years. Only the presence of interrupted aortic arch was independently associated with increased time-related mortality, the hazard ratio being 5.87 (p = 0.009). The outcome for an isolated lesion is excellent. Mortality occurs mainly before repair, mostly with complex associated lesions, particularly interruption of the aortic arch.
Aorta↗
Designing therapeutic strategies for patients with a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs.
The palliation of the cyanotic child with a dominant morphologically left ventricle, discordant ventriculo-arterial connections, and obstruction to the pulmonary outflow tract has continued to evolve and mature. The evolution began in the early days of surgical palliation with the Blalock-Taussig shunt, extended to construction of cavopulmonary shunts, if required, and then to the Fontan procedure and its subsequent modifications. This journey took nearly 30 years to complete. There is increasing clinical data to document the beneficial effects of this approach, with ever-improving outcomes. Some aspects of the history of the cavopulmonary shunt have been previously reviewed in this journal and elsewhere, as have analysis of outcomes for some groups of patients considered for surgical completion of the Fontan circulation. While there has been some ongoing interest in ventricular septation since the early success of Sakakibara et al., this approach has largely been abandoned. Considerably more challenges and debate resonate in the surgical algorithms defined for patients whose hearts are characterized by a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs. This latter group will be the focus of this review, as will the aetiology of the myocardial hypertrophy that is particularly frequent in this group of patients, its clinical recognition, indeed its anticipation, and the multiple surgical strategies designed to prevent or treat it. All these manoeuvres are considered to optimise suitability for, and outcome from, creation of the Fontan circulation.
Cardiac Surgical Procedures↗
Percutaneous balloon valvotomy in pulmonary atresia with intact ventricular septum: impact on patient care.
BACKGROUND: Pulmonary atresia with intact ventricular septum (PA-IVS) is a rare congenital lesion with high mortality. Therapy was exclusively surgical until recently, when the use of radiofrequency-assisted perforation of the atretic valve was introduced as a treatment option. This study analyzes the outcomes and morphological changes to right heart structures after percutaneous perforation and balloon dilation of the atretic valve. METHODS AND RESULTS: Between April 1992 and August 2000, 30 patients with PA-IVS underwent attempted percutaneous valve perforation and balloon dilation of the pulmonary valve. Longitudinal echocardiographic measurements of the tricuspid valve diameter, right ventricular length and area were recorded. Z scores were calculated according to published formulas. Perforation was achieved in 27 patients. In 14 patients a modified Blalock-Taussig shunt was performed between 2 and 24 days after valve dilation. There were 3 early and 2 late deaths. Among the survivors (follow-up time of 1 to 87 months), 16 patients had a biventricular circulation, 3 a 1(1/2)-ventricle circulation, and 1 a Fontan operation. Four patients are awaiting further palliation. There was no significant change of the tricuspid valve Z score or right ventricular length Z score with time. CONCLUSIONS: Percutaneous balloon valvotomy is an effective treatment strategy for patients with PA-IVS provided that there is a patent infundibulum and a lack of a right ventricle-dependent coronary circulation. Despite the observation that right heart growth does not increase with body growth in early follow-up, it appears adequate to maintain a biventricular circulation in many patients.
Angiography↗
Outcomes of uncomplicated aortic valve stenosis presenting in infants.
BACKGROUND: The management of uncomplicated aortic valve stenosis presenting with critical obstruction in infants continues to be associated with significant morbidity and mortality. However, not all infants have critical obstruction, and outcomes spanning the broader spectrum of disease severity are less well defined. METHODS: In a 12-year period, 55 infants (<3 months of age) were seen with aortic valve stenosis and with anatomy suitable for biventricular repair. Clinical, echocardiographic, angiographic, management, and outcome data were reviewed. RESULTS: Status at presentation (median age 6 days) included signs of congestive heart failure in 20 patients, cardiovascular collapse in 5 patients, and an asymptomatic heart murmur in 30 patients. The initial echocardiogram showed reduced left ventricular function in 26% of patients, with a mean peak instantaneous gradient of 69 +/- 30 mm Hg in patients with normal function. There were 5 deaths (9%), all in patients with poor ventricular function. The initial intervention was balloon valvotomy in 24 patients and surgical valvotomy in 20 patients, with 11 patients having no intervention to date. The freedom-from-intervention rate was 69% at age 1 week, 58% at 1 month, 36% at 3 months, and 28% at 1 year. Patients without cardiovascular collapse, normal left ventricular function, and gradients <60 mm Hg at presentation (n =1 9) had better survival and longer freedom from intervention than patients with poor ventricular function or gradients >or=60 mm Hg (n = 36, P =.0001). CONCLUSION: Most infants with aortic valve stenosis receive intervention, although this may be safely delayed in selected patients with lower initial gradients and good left ventricular function.
Aortic Valve↗
Cineangiographic aortic dimensions in normal children.
Knowledge of normal aortic dimensions is important in the management of children with aortic disease. So as to define such dimensions, we undertook a retrospective review of clinical data and aortic cineangiograms from 167 subjects without aortic disease having a mean age of 3.67 years, with a range from 0.01 to 14.95 years. Amongst the patients, 56 were without detectable cardiac lesions, 66 patients had mild pulmonary stenosis, 30 were seen with Kawasaki disease, and 15 with small interatrial defects within the oval fossa. Aortograms were available in all. No patient had any hemodynamic derangement that would have affected the aorta during intrauterine life or childhood. Systolic dimensions were measured in the ascending and descending aorta at the level of the carina, at the transverse aortic arch distal to the brachiocephalic, of the left common carotid artery at its origin, at the transverse aortic arch distal to the left common carotid artery, at the aortic isthmus, and of the aorta at the level of the diaphragm. A regression analysis model was used to establish the range of predicted normal values, with their confidence limits, standardizing the values to height as the biophysical parameter having the highest correlation to aortic dimensions. Normal ranges were established for all the levels of measurement. The data should prove useful in identifying abnormalities of the thoracic aorta during childhood, and when assessing the outcomes of interventions.
Adolescent↗
Physiological impact and transcatheter treatment of the persisting left superior caval vein.
A left superior caval vein frequently occurs in the malformed, as well as in the structurally normal, heart. Its physiological impact varies, and is determined by its connections and whether there are associated cardiac lesions. In this review, we describe 3 patients with such a vein, 1 without other lesions and 2 with the anomalous venous channel as a component of a complex cardiac malformation. In all cases, transcatheter techniques were used to treat the physiological dysfunction caused by the presence of the vein. The connections of the vein, and the complexity of the associated cardiac lesions, determine the options for treatment. We define the role of surgical as opposed to transcatheter intervention, and discuss strategies for transcatheter treatment.
Cardiac Catheterization↗
Echocardiographic evaluation, management and outcomes of bilateral arterial ducts and complex congenital heart disease: 16 years' experience.
Bilateral arterial ducts represent an uncommon form of pulmonary or systemic blood supply associated with complex congenital cardiac disease. We sought to determine the role of high-resolution cross-sectional echocardiography and color flow Doppler ultrasonography in assessing this condition, as well as to describe the management and outcome in a group of patients. A retrospective review was conducted of 11 newborns identified over a 16-year period as having bilateral arterial ducts. Pulmonary atresia associated with non-confluent pulmonary arteries was the dominant lesion, with the heterotaxy syndrome also frequently being recognized. Echocardiography best identified the source of blood supply to either the pulmonary or systemic circulations, allowing differentiation from collateral vessels. Stenosis of the right or left pulmonary artery at the initial site of ductal insertion needs careful evaluation on follow-up. Management of patients with this condition remains a challenge, as indicated by the poor outcomes observed in our series.
Coronary Circulation↗
Percutaneous stent implantation to stenotic bioprosthetic valves in the pulmonary position.
BACKGROUND: We evaluated stent implantation across stenotic bioprosthetic pulmonary valves in 9 patients. METHODS: Nine patients (6 male patients) underwent stent implantation across stenotic bioprosthetic pulmonary valves between July 1996 and July 1999 at the Hospital for Sick Children, Toronto. Catheter intervention was indicated if echocardiography revealed Doppler estimates of right ventricular pressure of more than two thirds of systemic arterial pressure (or systolic septal flattening with an estimated gradient of >60 mm Hg across the valve prosthesis). Catheterization was performed during general anesthesia at an age (mean +/- SD) of 9.3 +/- 3.5 years and a weight of 32.0 +/- 17.1 kg 5.9 +/- 1.8 years after surgical insertion of a bioprosthetic valve in the pulmonary position: 7 patients with tetralogy of Fallot, 1 patient with congenital pulmonary stenosis-insufficiency, and 1 patient after a Rastelli operation. All had systolic septal flattening and right ventricular dilatation with moderate-to-severe pulmonary insufficiency before intervention. Fluoroscopy times were 33.1 +/- 9.5 minutes. Seven patients received a single P4014 stent, and 2 received single P308 stents (Palmaz; Johnson & Johnson Interventional Systems, Warren, NJ) without significant complications. RESULTS: The right ventricular systemic pressure decreased acutely from 83% +/- 16% to 41% +/- 10% (P <.001, n = 9), and the transvalvular gradient decreased from 49.7 +/- 8.5 to 11.0 +/- 5.9 mm Hg (P <.001, n = 8). During the follow-up period (10.9 +/- 8.1 months, n = 8), 1 patient had an unsuccessful attempt at redilation of the stent (right ventricular pressure, 60% systemic) and underwent uneventful surgical pulmonary valve replacement. None of the remaining patients had echocardiographic evidence of systolic septal flattening, and right ventricular dimensions did not change significantly. CONCLUSION: Stent implantation is a safe and effective means of providing palliative relief of obstructed bioprosthetic valves in the pulmonary position and can safely delay the requirement for pulmonary valve replacement.
Bioprosthesis↗
Solitary arterial trunk with absence of the ascending aorta: embryologic considerations.
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Aorta↗