Pulmonary valve replacement late after repair of tetralogy of Fallot.

BACKGROUND: Pulmonary valve incompetence is usually well tolerated after tetralogy of Fallot repair but may result in late progressive right heart failure as manifested by increasing fatigue, dyspnea, and frequently arrhythmias. METHODS: All patients who underwent pulmonary valve replacement in our center late after repair of tetralogy of Fallot were reviewed. RESULTS: Eighty-five patients had elective pulmonary valve replacement late (median, 9.3 years) after repair. Operative risk was low (1.1%). Ninety percent of survivors are in New York Heart Association class I. Survival 10 years after pulmonary valve replacement is 95%, with 86% of the patients free of reoperation for valve failure. CONCLUSIONS: Pulmonary valve replacement is infrequently required after repair of tetralogy of Fallot. Pulmonary valve replacement may be performed electively with little risk; it improves symptoms of right heart failure and provides satisfactory long-term survival with low risk of early valve failure. As the population of patients who have had repair of tetralogy of Fallot ages, pulmonary valve replacement will become a more frequent consideration.

Arrhythmia and mortality after the Mustard procedure: a 30-year single-center experience.

OBJECTIVES: Our purpose was to assess the risk factors for late mortality, loss of sinus rhythm and atrial flutter after the Mustard operation. BACKGROUND: The Mustard operation provides correction of cyanosis with low surgical risk in transposition of the great vessels. However, right ventricular failure, loss of sinus rhythm, atrial flutter and death are frequent long-term complications. METHODS: Records of 534 children who underwent the Mustard operation at a single center since 1962 were reviewed for demographic, anatomic, electrocardiographic and physiologic predictors and outcomes. RESULTS: There were 52 early deaths (9.7%). Survival analysis was undertaken for 478 early survivors with a mean follow-up interval of 11.6 +/- 7.2 years. There were 77 late deaths (16.1%), with sudden death (n = 31) the most frequent cause. Survival estimates were 89% at 5 years and 76% at 20 years of age. Risk factors were an earlier date of operation, operative period arrhythmia and an associated ventricular septal defect. Risk (hazard) of late death declined in the first decade, with further peaks in the second decade. Sinus rhythm was present in 77% at 5 years and 40% at 20 years. Loss of sinus rhythm was associated with previous septectomy, postoperative bradycardia and late atrial flutter. Freedom from atrial flutter was 92% at 5 years and 73% at 20 years of age. Risk factors for atrial flutter were the occurrence of perioperative bradyarrhythmia, reoperation and loss of sinus rhythm during follow-up. Risk of atrial flutter demonstrates a late increase. CONCLUSIONS: Ongoing loss of sinus rhythm and late peaks in the risk of atrial flutter and death necessitate continued follow-up.

Augmentation of pulmonary blood flow with an axillary arteriovenous fistula after a cavopulmonary shunt.

Of 320 children with cyanotic congenital heart malformations who had previously undergone cavopulmonary shunt operations, 11 had increasing cyanosis and exercise intolerance and were considered unsuitable for definitive repair, a Fontan procedure, or other palliation. Eight had a previous Glenn shunt and three had a previous bidirectional cavopulmonary connection. To augment pulmonary blood flow, 10 patients underwent creation of an ipsilateral axillary arteriovenous fistula. Mean oxygen saturations were 80% +/- 2% before operation, 85% +/- 2% immediately after operation, and 84% +/- 3% at a mean follow-up interval of 7.4 years (range 0.1 to 15.5 years). Mean hemoglobin values were 202 +/- 10 gm/L before operation, 177 +/- 10 gm/L after operation, and 191 +/- 14 gm/L at latest review. The only complication was mild swelling of the arm distal to the fistula in one patient. All patients reported improvement in exercise tolerance. Eight patients have continued evidence of fistula patency. Development of ipsilateral pulmonary arteriovenous fistulas has not been observed in any patient. Creation of an axillary arteriovenous fistula to augment pulmonary blood flow after a cavopulmonary shunt provides useful palliation for complex cyanotic heart disease when other options are limited. Such additional sources of pulmonary blood flow may influence the development of pulmonary arteriovenous fistulas.

Reoperation for recurrent aortic coarctation.

BACKGROUND: Recurrence of stenosis is a complication of coarctation repair associated with major long-term morbidity. Persistent or exercise-provoked hypertension may indicate recurrent coarctation. Patients failing or not amenable to balloon dilation should be managed surgically. METHODS: A retrospective chart review was performed. RESULTS: Forty-three patients were identified as having undergone repeat surgical intervention for recurrent aortic coarctation between the years 1976 and 1993 at The Hospital for Sick Children in Toronto. Seventy percent of the children had other congenital cardiac anomalies. Eighty-six percent of patients initially treated by subclavian flap aortoplasty or end-to-end anastomosis were managed at reoperation by patch aortoplasty, and 26% of patients also required augmentation of the transverse arch (under hypothermic circulatory arrest) for accompanying hypoplasia. Three patients underwent a second reoperation; all were treated at this reoperation with tube graft interposition. CONCLUSIONS: No ischemic spinal injury occurred in patients managed with either simple proximal aortic cross-clamping or cardiopulmonary bypass. No patient treated with transverse arch augmentation required further surgical intervention. Mortality at reoperation was 7% (3 patients), similar to that of first-time coarctation repair. At follow-up (mean duration, 4.5 years), 57% of patients are normotensive, with no measurable arm-leg gradient.

Subaortic stenosis in the spectrum of atrioventricular septal defects. Solutions may be complex and palliative.

UNLABELLED: From July 1982 through September 1994, 19 children had operative treatment of subaortic stenosis associated with an atrioventricular septal defect. Specific diagnosis were septum primum defects in 7, Rastelli type A defects in 6, transitional defects in 4, inlet ventricular septal defect with malattached chordae in 1, and tetralogy of Fallot with Rastelli type C defect in 1. Twenty-seven operations for subaortic stenosis were performed. Surgical treatment of the outlet lesion was performed at initial atrioventricular septal defect repair in 3 children and in the remaining 16 from 1.2 to 13.1 years (mean 4.9 years, median 3.9 years) after repair. Eighteen of the 19 children had fibrous resection and myectomy for relief of obstruction. Seven children had an associated left atrioventricular valve procedure. One child received an apicoaortic conduit. Seven children (36.8%) required 8 reoperations for previously treated subaortic stenosis. Time to the second procedure was 2.8 to 7.4 years (mean 4.9 years). Follow-up is 0.4 to 14.0 years (median 5.6 years). Six-year actuarial freedom from reoperation is 66% +/- 15%. The angle between the plane of the outlet septum and the plane of the septal crest was measured in 10 normal hearts (86.4 +/- 13.7) and 10 hearts with atrioventricular septal defects (22.2 +/- 26.0; p < 0.01). The outflow tract can be effectively shortened, widened, and the angle increased toward normal by augmenting the left side of the superior bridging leaflet and performing a fibromyectomy. CONCLUSION: Standard fibromyectomy for subaortic stenosis in children with atrioventricular septal defects leads to a high rate of reoperation. Leaflet augmentation and fibromyectomy may decrease the likelihood of reoperation.

Determinants of success in pediatric cardiac patients undergoing extracorporeal membrane oxygenation.

BACKGROUND: The purpose of this retrospective study is to determine the possible predictors of successful cardiac recovery using extracorporeal membrane oxygenation (ECMO) and the practical limits of ECMO support. METHODS: Information was gathered on 31 consecutive children with myocardial failure who could not be resuscitated with other means and underwent ECMO at the Hospital for Sick Children before January 1994. RESULTS: Of the children who underwent ECMO as a means of cardiac rescue, 14/31 (45%) were weaned successfully. Two distinct groups of children were evident based on their initial indications for ECMO: those who had postcardiotomy myocardial dysfunction (n = 25) and those with cardiomyopathy or myocarditis (n = 6). Children with residual defects after cardiotomy (n = 10) did not survive ECMO. Four of the 6 children with cardiomyopathy or myocarditis were weaned successfully. In either group of patients ECMO support beyond 6 days failed to resuscitate the myocardium; all attempts to violate this "time barrier" in our study inevitably failed. CONCLUSIONS: Postcardiotomy residual defects are a contraindication to ECMO. If children with residual defects are excluded, successful weaning from ECMO can be achieved in almost 70%, with almost all recovery occurring with the first 6 days of ECMO.

Right atrial lipoma.

The case of a patient undergoing successful surgical resection of a huge lipoma of the right atrium is presented. The diagnosis was established preoperatively by magnetic resonance imaging. The tumor was involved intimately with the right coronary artery, and careful identification and dissection were required to preserve the vessel. The tumor was removed successfully, and follow-up at 1 year showed no evidence of recurrence.

Small aortic root in childhood: surgical options.

Aortic valve replacement in the pediatric population is complicated by the often complex nature of the left ventricular outflow tract obstruction. Techniques to enlarge the annulus frequently are necessary. From 1977 to 1991, 32 children underwent an annular enlargement procedure at The Hospital for Sick Children, Toronto. During this same era, 110 children underwent a total of 138 aortic valve replacements. Eleven had the annulus enlarged with a posterior patch technique and implantation of a valve (mechanical 8, porcine heterograft 2, homograft 1) ranging from 20 to 25 mm in diameter. Twenty-two children had an anterior annular enlargement (aortoventriculoplasty) and aortic valve replacement with a valve (mechanical 8, porcine 2, homograft 12) 12 to 27 mm in diameter. One child had a posterior patch enlargement performed, followed by a second operation involving anterior annular enlargement. There was one early death in the posterior annuloplasty group and one late death due to failure of a bioprosthetic valve. There were five hospital deaths in the anterior annuloplasty group (22%; 70% confidence interval [CI], 14% to 32%) and two late deaths. Actuarial survival for the 32 children was 78% (70% CI, 70% to 86%) at 5 years and 65% (70% CI, 48% to 82%) at 10 years after repair. Younger children (age less than 1 year) had a significantly worse survival at 5 years (33%; 70% CI, 14% to 52%) than older children (88%; 70% CI, 82% to 95%). The survivors are well, and no reoperations have been necessary because of the children's outgrowing their valve.

Risk factors for atrial tachyarrhythmias after the Fontan operation.

OBJECTIVES: The purpose of this study was to define the incidence and risk factors for atrial tachyarrhythmias after the Fontan operation. BACKGROUND: Atrial tachyarrhythmias cause morbidity after the Fontan operation. Causative factors may be affected by the type of systemic to pulmonary connection. METHODS: The Fontan operation was performed in 270 consecutive patients between 1982 and 1992. The mean age at operation was 7.0 +/- 4.3 years. Direct atriopulmonary connection was used in 138 patients (51%), total cavopulmonary connection in 94 (35%) and right atrial to right ventricular connection in 38 (14%). RESULTS: Atrial tachyarrhythmias were seen early postoperatively in 55 patients (20%), preoperative atrial tachyarrhythmia being the only risk factor. Follow-up was achieved for 228 early survivors (97%) at a mean interval of 4.4 years. There were 20 late deaths. Late atrial tachyarrhythmias were noted in 29% of patients who received an atriopulmonary connection, 14% of those who received a total cavopulmonary connection and 18% of those who received a right ventricular connection (p < 0.02). Significant risk factors as determined by univariate and multiple logistic regression analysis were atriopulmonary connection type (odds ratio 0.40 for total cavopulmonary relative to atriopulmonary connection [p < 0.05] and 0.37 for right ventricular relative to atriopulmonary connection [p = 0.08]), longer follow-up interval (odds ratio 1.32 for each consecutive year [p < 0.002]) and atrial tachyarrhythmia in the operative period (odds ratio 6.31 [p < 0.0001]). CONCLUSIONS: Early postoperative atrial tachyarrhythmias, length of follow-up and atriopulmonary connection are significant independent risk factors for the presence of late atrial tachyarrhythmias.

Experience with the Damus-Kaye-Stansel procedure for children with Taussig-Bing hearts or univentricular hearts with subaortic stenosis.

Anastomosis of the pulmonary artery to the ascending aorta is the essence of a technique for repair of complete transposition proposed by Damus, Kaye, and Stansel. Our Institutional experience with the Damus-Kaye-Stansel procedure (DKS) is limited to 9 children with double-outlet right ventricle and 38 with univentricular heart plus subaortic stenosis. Thirty-eight children (81%) survived the DKS procedure, and there were three late deaths during the mean follow-up of 3.1 years. Five-year survival is 72% (+/- 8%). All six children surviving a DKS and biventricular repair of double-outlet right ventricle have required conduit replacement at a mean interval of 46 months. In the children with univentricular heart, relief of subaortic stenosis with the DKS was successful in all except two. The late function of the semilunar valves is of concern, as 36% of the aortic and 52% of the pulmonary valves have some degree of incompetence.

Survival analysis of infants under age 18 months presenting with tetralogy of Fallot.

The trend to perform early primary repair of tetralogy of Fallot prompted us to review our experience in the current era with the traditional protocol consisting of palliation during infancy, if required, and repair after infancy. During a 10-year period, 270 infants with tetralogy of Fallot presented aged less than 18 months. Thirteen infants (4.8%) had major noncardiac lesions that precluded definitive care for their congenital heart disease. Twenty infants (7.4%) had major associated cardiac lesions (atrioventricular septal defect or absent pulmonary valve syndrome, or both). Survival in this group was poor, with only 58% +/- 12% reaching the age of 10 years. Four of the seven deaths occurred before intracardiac repair was performed. The remaining 237 infants presented with isolated tetralogy of Fallot. Eight-nine percent +/- 2.3% survived to age 10 years. Sixty percent of these infants required palliation, and survival in these infants did not differ from that in those who never required palliation. However, 19 infants (8%) required palliation in the first month of life. In these children, survival to age 10 years was significantly lower (77%), secondary palliation was frequently required (n = 11), and a transannular patch or conduit at the time of repair (10 of 14 patients) was more likely needed than it was in children who had not undergone a palliative procedure during the neonatal period. The survival in infants with tetralogy of Fallot is unlikely to be different, regardless of whether primary repair or a staged repair is carried out. The quality of survival, including the exercise capability and absence of arrhythmias, must be assessed to determine which protocol is superior.

Ventriculo-coronary arterial connections in pulmonary atresia with intact ventricular septum, and their influences on ventricular performance and clinical course.

To define the influence of ventriculo-coronary (VC) arterial connections on ventricular performance and late outcome, and associated wall motion abnormalities in patients with pulmonary atresia and intact ventricular septum, 21 patients aged > or = 6 months (mean 4.3 +/- 3.3 years, range 0.5 to 11.8) were reviewed. Ventricular volumes, mass, systolic functional variables and regional wall motion were measured using biplane ventricular cineangiography. Fourteen patients had VC connections, 11 of whom had coronary artery abnormalities. In comparing patients with VC connections and coronary abnormalities (group I) with those without coronary abnormalities (group II), no hemodynamic differences were observed, except the expected increased right-to-left ventricular systolic pressure ratio in group I (1.33 +/- 0.24 vs 0.72 +/- 0.50). Wall motion abnormalities were observed in 8 patients (7 in group I, and only 1 in group II [p < 0.05]). Ejection fraction in patients with abnormal wall motion was significantly lower (50 +/- 6% vs 57 +/- 7%; p < 0.05) and ventricular systolic pressure ratio significantly higher (1.46 +/- 0.16 vs 0.80 +/- 0.45; p < 0.05) than in those with normal wall motion. Five patients died during follow-up, all of whom had wall motion abnormalities. The findings suggest that patients with VC connections and coronary abnormalities have a higher incidence of wall motion abnormalities, which may reflect ongoing ischemia, and are at risk for late death.

Failure of cryopreserved homograft valved conduits in the pulmonary circulation.

BACKGROUND: This study evaluates our experience with the cryopreserved homograft valved conduit used for reconstruction of the pulmonary circulation in patients with congenital heart disease. METHODS AND RESULTS: Between July 1, 1985, and December 31, 1990, 219 patients had cryopreserved homograft extracardiac valved conduits placed in the pulmonary circuit. Average age at operation was 7.2 years. Of these, 132 patients had a pulmonary homograft, and 87 had an aortic homograft. Twenty-four patients (11%) died in hospital. Hospital survivors (n = 195) have been followed an average of 29.8 months (SD, +/- 18.4 months). Fourteen patients died during follow-up, almost all related to the complexity of their original cardiac malformation. Thirty-two patients (15%) have required reoperation for conduit-related problems. Actuarial freedom from conduit reoperation is 55 +/- 12% at 5 years. The most common indication for reoperation was calcific stenosis (n = 27). Other indications for reoperation were pseudoaneurysm (n = 2), conduit infection (n = 2), and pulmonary insufficiency (n = 1). Reoperation rate for patients with aortic homografts (16 of 87) compared with that for pulmonary homografts (16 of 132) was not significantly different by the actuarial method. CONCLUSIONS: Long-term function of cryopreserved homograft valved conduits in the pulmonary circulation is disappointing.

Surgical connections from ventricle to pulmonary artery. Comparison of four types of valved implants.

BACKGROUND: Four types of valved conduits used to correct venous ventricle to pulmonary artery (V-PA) discontinuity were compared. METHODS AND RESULTS: Four hundred fifty-seven patients with congenital heart defects requiring a V-PA connection during the past 25 years were reviewed. Age at implant varied from 1 day to 64 years (mean, 9.1 years). Four types of valved prostheses were used: 1) homograft conduit (HC, n = 178), 2) valved Dacron conduit (VDC, n = 126), 3) polystan conduit (PC, n = 47), and 4) orthotopic pulmonary valve implant (PVI, n = 106). There were 83 early deaths (18.2%) and 34 late deaths (8.5%). Follow-up ranged from 1 month to 22 years (mean, 3.5 years). One hundred eight conduit replacements were performed in 93 patients (21%). The overall patient survival was 73 +/- 2.3%, 67 +/- 3.2%, and 56 +/- 6.8% at 5, 10, and 15 years, respectively. Factors predictive of patient survival were diagnosis (p < 0.001) and valve size (p < 0.001). Age at operation (p < 0.001) and type of valve (p < 0.001) were the only risk factors for valve survival. At 5 years, survival of PVI (89 +/- 5%) and VDC (89 +/- 4%) was significantly better than survival of HC (46 +/- 13%) or PC (57 +/- 9%). CONCLUSIONS: Patients who survived the initial construction of a V-PA conduit had a reasonable long-term survival. A PVI was the most durable prosthesis. A Dacron porcine-valved conduit had significantly better durability than either a cryopreserved homograft or a PC.

The recognition, identification of morphologic substrate, and treatment of subaortic stenosis after a Fontan operation. An analysis of twelve patients.

Twelve children were identified with subaortic stenosis after Fontan's operation. All had absent resting and isoproterenol-provoked pressure gradient before the Fontan procedure. Six had a univentricular heart of left ventricular morphology, three had a single ventricle of right ventricular morphology, one had tricuspid atresia with transposition of the great arteries, one had pulmonary atresia, intact ventricular septum, and hypoplastic right ventricle, and one had corrected transposition with hypoplastic systemic ventricle. The median interval between the Fontan operation and the recognition of subaortic stenosis was 2.5 years. Ten patients underwent surgical treatment after a prior Fontan operation: Five had myectomy and enlargement of ventricular septal defect with two operative deaths; two had placement of a valved conduit from the ventricular apex to the descending aorta, and both died postoperatively; two with single ventricle had subaortic myectomy, and one had enlargement of ventricular septal defect and pulmonary aortic connection. Complete heart block developed in only one patient. Postoperative testing with Doppler echocardiography with color flow imaging demonstrated good relief of subaortic stenosis. All six children who survived the operation are well 4 months to 4 years later. Subaortic stenosis is a progressive lesion that may develop after a Fontan operation. Its surgical treatment continues to carry a significant mortality. Myectomy and enlargement of ventricular septal defect achieve direct relief of the obstruction with minimal risk of heart block.

Late results after repair of aortic insufficiency associated with ventricular septal defect.

The late results of 70 patients aged 1.96 to 35.9 (mean 10.1) years who had repair of ventricular septal defect and aortic insufficiency from 1968 to 1988 were reviewed. The ventricular septal defect was subcristal in 50 and subpulmonary in 20 patients. Two thirds were situated immediately below some part of the right coronary leaflet with prolapse of that leaflet. Most of the remainder were below the right commissure or the anterior part of the noncoronary leaflet with prolapse of one or both adjacent leaflets. Associated structural defects, usually including some fusion at a commissure, were present in 18 of the 70 patients and occurred more often with a ventricular septal defect in or below the commissure between the right and noncoronary leaflets (p less than 0.001). Follow-up ranged from 1.9 to 19.6 (mean 9.8) years. There were no early deaths or cases of atrioventricular block, but there were two late deaths. Patient survival rate was 96% at 10 years. Freedom from valvuloplasty failure and freedom from reoperation were 76% and 85%, respectively, at 10 years. The major predictor for failure by multivariate analysis was the presence of an associated structural defect (p less than 0.01). Age at repair and position of the ventricular septal defect were not significant risk factors. We conclude that aortic valvuloplasty produces good palliation in most children. The few failures occurred early and chiefly in patients with associated structural valve defects that occurred more frequently in children who had a ventricular septal defect in the right commissure, where both the right and noncoronary leaflets may be affected.

Abnormalities in von Willebrand factor and antithrombin III after cardiopulmonary bypass operations for congenital heart disease.

In patients with congenital heart disease two poorly understood postoperative complications are pulmonary hypertensive crises after repair of large atrioventricular or ventricular septal defects and right atrial and pulmonary thrombi after the Fontan operation. In this study we assessed whether cardiopulmonary bypass in these patients is associated with the release of agents that might induce platelet aggregation and vasoconstriction, such as biologically active von Willebrand factor and platelet-activating factor. In addition, we measured levels of anticoagulants such as antithrombin III and proteins C and S. Three groups of patients with congenital heart disease undergoing cardiopulmonary bypass were monitored through the perioperative period for secundum atrial septal defects, large atrioventricular or ventricular septal defects, and tricuspid atresia or univentricular heart (Fontan candidates). Control values were obtained from age-matched patients; patients requiring major noncardiac operations and those with cardiac disease not requiring cardiopulmonary bypass were also studied. After cardiopulmonary bypass in all three groups biologic activity of von Willebrand factor increased markedly in the immediate and early postoperative periods compared with preoperative values, whereas antithrombin III values were decreased. Platelet-activating factor was detected in only two patients with congenital heart disease, both in the early postoperative period. In contrast, patients who did not have cardiopulmonary bypass did not show these abnormalities. All measured parameters normalized at late follow-up (6 to 18 months after operation). Although cardiopulmonary bypass in these patients resulted in increased von Willebrand factor activity and decreased antithrombin III, changes that may predispose the patient to platelet aggregation and thrombus formation, absolute values in individual patients alone were not predictive of pulmonary hypertensive crises or detectable thrombi. This suggests that these hematologic abnormalities may contribute to but are not by themselves a cause of morbidity in the early postoperative period. Moreover, the increased von Willebrand factor biologic activity seen postoperatively in patients with congenital heart disease suggests that use of synthetic vasopressin may be ineffective and potentially detrimental.

Results of the Fontan procedure for patients with univentricular heart.

One hundred twenty-four consecutive patients with univentricular heart undergoing the Fontan operation were reviewed. Patients with tricuspid atresia or biventricular heart with hypoplasia of one ventricle were excluded. Eighty-four patients had left ventricular morphology. Atrioventricular connection was double-inlet (n = 76), common (n = 29), absent left atrioventricular connection (n = 14), and absent right atrioventricular connection (n = 5). Actuarial survival was 77% (70% confidence limits, 73% to 81%) at 1 year, 66% (70% confidence limits, 60% to 72%) at 5 years, and 49% (70% confidence limits, 36% to 61%) at 10 years, indicating a continuing risk for premature death. Multivariate analysis identified preoperative ventricular function and hypertrophy as risk factors for survival. High postrepair right atrial pressure (greater than 15 mm Hg) emerged as a strong intraoperative predictor of survival. Logistic regression analysis of these factors predicts high probability of death for certain subgroups of patients after the Fontan operation. Forty-four percent (n = 53) of these original 124 patients are alive and in New York Heart Association class I at follow-up. Thirty-eight percent (n = 33) of survivors have worse ventricular function than preoperative. Long-term survival is disappointing. Certain identifiable subgroups of patients with univentricular heart have unacceptable risks for the Fontan operation and should have alternate management. High postrepair right atrial pressure is an ominous sign, and if it persists the Fontan should be fenestrated or taken down.

Expression of ventricular myosin subunits in the atria of children with congenital heart malformations.

The presence of ventricular myosin light chains in the atria of children with congenital heart disease was demonstrated by two-dimensional polyacrylamide gel electrophoresis, peptide mapping, and Western blot analysis. Ventricular myosin light chains were present in 27% of biopsies from 91 children with different forms of congenital heart disease. Perimembranous ventricular septal defects and tetralogy of Fallot were associated with the presence of ventricular myosin light chains in 50% of patients. The presence of ventricular myosin light chains in these atria did not correlate with pressure or volume overload. Analysis of myosin heavy chain isotype in the same biopsies by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, peptide mapping, and Western blot analysis indicated that there was no detectable expression of ventricular myosin heavy chain (beta-subunit), suggesting that the genes for the myosin heavy chains and light chains are not expressed coordinately.