Pulmonary hypertension after operations for congenital heart disease: analysis of risk factors and management.

BACKGROUND: Management of pulmonary hypertension, a potentially fatal complication of operations to correct congenital heart disease, has evolved through the last 15 years. Monitoring of pulmonary arterial pressure and mixed venous saturation became available, and prophylactic use of alpha-blockers and other vasodilators increased. This study examines risk factors for morbidity and mortality from pulmonary hypertension after operations to correct congenital heart disease and evaluates the impact of management changes on outcomes. METHODS: By means of multivariable logistic regression analysis, 880 high-risk patients with congenital heart disease (of 2484 patients undergoing cardiopulmonary bypass between January 1980 and December 1994) were analyzed to determine which were at risk for postoperative pulmonary hypertension and its associated morbidity and mortality. RESULTS: Patients with atrioventricular canal (n = 182), truncus arteriosus (n = 47), total anomalous pulmonary venous connection (n = 90), transposition of great arteries (n = 97), hypoplastic left heart syndrome (n = 50), and ventricular septal defect (n = 414) demonstrated a higher risk of postoperative pulmonary hypertension. By multivariable logistic regression, preoperative pulmonary hypertension (p < 0.0001), absence of mixed venous saturation monitoring (p < 0.0001), and absence of prophylactic alpha-blockade (p = 0.0004) significantly increased postoperative pulmonary hypertension. Preoperative pulmonary hypertension (p < 0.001) and absence of prophylactic alpha-blockers (p = 0.0004) were significant risk factors for in-hospital death related to pulmonary hypertension. Repair at older age (except in the case of total anomalous pulmonary venous connection) was a significant risk for postoperative pulmonary hypertension (p = 0.03). CONCLUSION: Mixed venous saturation monitoring and alpha-receptor blockade reduced the incidence of pulmonary hypertension after operations for congenital heart disease. Early definitive repair reduced morbidity and mortality from postoperative pulmonary hypertension.

Combined Registry for the Clinical Use of Mechanical Ventricular Assist Pumps and the Total Artificial Heart in conjunction with heart transplantation: sixth official report--1994.

BACKGROUND: The Combined Registry has existed since 1985 with a design toward the voluntary submission of data from centers undertaking mechanical circulatory assistance. METHODS: The compiled results of the Combined Registry for the Clinical Use of Mechanical Ventricular Assist Pumps and the Total Artificial Heart was reviewed and subjected to strict statistical evaluation. RESULTS: More than 2000 implanted devices have been reported through January 1994, and 584 of these have been placed with the intention of bridge to heart transplantation. Nearly 70% of these patients have subsequently undergone heart transplantation, and 69% of those patients have survived to discharge from the hospital. Outcome statistics continue to favor isolated left ventricular support, although only discharge rates are significantly improved over right (p = 0.01) or biventricular assistance (p < 0.001) and the total artificial heart (p < 0.001). Within the group of left ventricular devices no individual mode of support proved advantageous over the others for transplantation or discharge rates. The 30-day mortality for all devices is approximately 36%, which remains much higher than that for orthotopic heart transplants. Isolated left ventricular support, however, had a 30-day mortality of only 9% with similar improvement in 12- and 24-month survival. CONCLUSIONS: These data show the continued success with these devices for bridging critically ill patients to transplantation. Additionally, it supports the ongoing development of devices implanted for long-term use, which might replace orthotopic transplantation for those patients currently deemed marginal candidates.

Aprotinin therapy for insertion of ventricular assist devices for staged heart transplantation.

Bleeding after insertion of ventricular assist devices is a common problem which carries a major risk of immediate and late complications. We evaluated the safety and efficacy of aprotinin in six patients undergoing staged heart transplantation and compared the results with those of six patients who received no aprotinin. The groups did not differ significantly with respect to age, gender, preoperative cause of cardiomyopathy, or cardiopulmonary bypass time. Patients treated with aprotinin had a significant reduction in postoperative chest tube drainage (743 +/- 457 versus 2036 +/- 1184 cc, respectively, for aprotinin therapy versus no therapy; p = 0.047). Blood transfusion requirements were reduced in patients treated with aprotinin (2.2 +/- 2.2 versus 10.7 +/- 7.1 U respectively, for aprotinin therapy versus no therapy; p = 0.038). No demonstrable serious side effects were attributed to the aprotinin treatment. We conclude that aprotinin is effective in reducing bleeding and transfusion requirements without increasing the incidence of clinically significant renal dysfunction or thromboembolic events.

Mechanical ventricular assistance: an economical and effective means of treating end-stage heart disease.

BACKGROUND: Heightened awareness of medical costs has escalated criticism toward expensive medical therapy. METHODS: The use of ventricular assistance devices (VADs) at Pennsylvania State University as a bridge to transplantation was reviewed. Records of 43 patients listed as status 1 from July 1991 to July 1994 were compared. RESULTS: This analysis demonstrated that for all patients treated with the intent to transplant, those who were bridged with a VAD exhibited a trend toward an improved transplantation rate (92% versus 68%) and a significantly greater rate of discharge from the hospital (92% versus 55.4%; p = 0.023) than the medically managed patients. Although overall charges and costs were higher in VAD-supported patients, this was related to significantly longer pretransplantation hospitalization. When normalized to daily costs and charges, this discrepancy in expenses was eliminated. CONCLUSIONS: The superior rate of discharge at equitable daily costs and charges for the VAD patients draws continued enthusiasm toward use of these devices as a bridge to transplantation. Furthermore, development of outpatient care for VAD-supported patients and continued advances in the use of these devices may further reduce the cost of managing these critically ill patients.

Heart transplantation for tumor.

Unresectable cardiac tumors, although unusual, are often rapidly fatal. A 31-year-old woman presented with a large tumor arising from the left ventricle and causing symptoms of a constrictive cardiomyopathy. After evaluation with echocardiography, angiography, and computed tomography, an exploration was carried out to confirm the extent of disease. Orthotopic heart transplantation was subsequently performed when a donor organ became available. She is now alive and disease-free 12 months after transplantation.

Transthoracic echocardiographic power motion tissue imaging of an intracardiac tumor that could not be seen with conventional transthoracic echocardiographic recordings.

Power motion imaging allows interrogation of low-velocity tissue. By means of power motion imaging with 2 different late-model echographs we identified an intra-atrial tumor that was undetectable on conventional transthoracic echocardiograms.

Hemodynamic performance of carotid artery shunts.

Although the use of shunts for carotid artery surgery remains controversial, the hemodynamics of the shunts currently available have not been carefully evaluated in vivo. We developed an animal model using contralateral carotid artery ligation, which produced ipsilateral carotid blood flows (640 +/- 44 ml/min) and internal carotid stump pressures (52 +/- 4 mm Hg) over a range commonly seen in carotid artery surgery. Seven shunts were tested and included Javid; 10F and 8F Brener; and 14F, 12F, 10F, and 8F Argyle shunts. The hemodynamic features evaluated for each shunt included maximum shunt flow, the pressure gradients occurring across each shunt, the increase in cerebral perfusion pressure over occlusion pressure associated with shunt placement, and the distal pressure pulse waveform. The larger diameter shunts were consistently better than the smaller diameter shunts. The correlation between shunt flow and the increase in distal pressure produced by shunt placement was high (r = 0.98, p less than 0.05), confirming that high flow rates maintained high perfusion pressure. By relating maximum shunt flow and the pressure gradient to the change in the pressure pulse contour for each shunt, it could be demonstrated that at the larger diameters, straight shunts displayed superior hemodynamic characteristics compared with tapered shunts, whereas at smaller diameters, tapered shunts were superior.

Establishment of a clinically correlated human pericardial fluid bank: evaluation of intrapericardial diagnostic potential.

The development of a clinically correlated human pericardial fluid bank and database is described. A unique feature of this registry is the availability of a large number of pericardial fluid samples for testing with respect to multiple factors and for correlation with angiographic findings and clinical syndromes expressed by the patients. The collection of data at the present time comprises frozen pericardial fluid samples obtained from patients who have undergone cardiac surgery; and historical, clinical, and laboratory data obtained from the patient records. Nearly 400 samples have been stored and analyzed thus far, with sample entry continuing. This registry is designed to evaluate the local factors that play a role in mediating or reflecting myocardial or coronary responses. Pathophysiologic processes of particular interest include restenosis, plaque ruptures, and angiogenesis. Study of the pericardial fluid bank should lead to enhanced understanding of molecular mechanisms, as well as to the explanation for the reasons underlying interpatient variability in these processes. It is further anticipated that this information might provide a foundation for the diagnostic use of pericardial fluid to individualize therapies targeting angiogenesis or plaque physiology.

Long-term left ventricular assist device use before transplantation.

Between September 1992 and April 1995, 19 patients at the authors' institution received pneumatic, pulsatile left ventricular assist devices (LVADs) for bridging to cardiac transplantation. The mean (+/- SD) age of the patients was 51 +/- 14 years (range, 19-64 years). Nine (47%) patients had end-stage idiopathic cardiomyopathy, five (26%) had ischemic cardiomyopathy, and five (26%) other recipients were in cardiogenic shock caused by acute myocardial infarction (AMI). Fifteen (79%) patients were supported with an intraaortic balloon pump or centrifugal LVAD at the time of LVAD insertion (duration, 5.5 +/- 4.1 days). Aprotinin was given to limit bleeding; heparin, followed by warfarin sodium, was used for anticoagulation. A vigorous exercise and nutrition protocol was followed. Cardiac index averaged 2.94 +/- 0.87 L/min/m2 immediately after the implantation procedure. No patient required placement of a right VAD. Average duration of LVAD support was 45 +/- 39 days (range, 3-153 days). Major complications included bleeding requiring reoperation (three patients); cerebrovascular accident (three patients); and severe dysrhythmias requiring direct current cardioversion (four patients). Fourteen (74%) patients underwent transplantation, with one patient still being mechanically supported. All of the patients receiving transplants were discharged from the hospital. Of the individuals who died while supported with the LVAD, 75% were patients with AMI. Timely application of LVADs as part of the interdisciplinary management of end-stage heart disease has generated excellent results for transplant candidates. Right ventricular dysfunction has not necessitated right VAD placement in the authors' experience. Patients with AMI have a higher risk of death while being supported with the device than do more chronically ill recipients.

Results of mechanical ventricular assistance for the treatment of post cardiotomy cardiogenic shock.

The voluntary submission of data on patients who receive mechanical circulatory assistance for post cardiotomy cardiogenic shock and acute myocardial infarction has resulted in an established data base for the ongoing evaluation of these devices. Since its inception in 1985, there have been 1,279 cases reported of implanted ventricular assist devices for post cardiotomy cardiogenic shock. The average duration of support for these devices is approximately 4 days. Those patients who underwent implantation of a centrifugal pump had significantly shorter periods of support when compared with the pneumatically supported group. Patients had similar periods of support when comparing clinical outcome. Approximately 70% of the reported cases underwent centrifugal assistance. The majority of reported cases were supported with isolated left ventricular assistance. There was no significant difference in overall outcome statistics when comparing type or mode of support. Approximately 45% of reported patients were weaned from circulatory assistance, and 25% of all patients survived to discharge. These numbers remain consistent with previously reported statistics. The results with acute myocardial infarction remain limited. Of the 96 reported patients, 26% were weaned from support and only 11.5% survived to discharge. This report continues to support the use and research for advancement of these devices toward the treatment of post cardiotomy cardiogenic shock.

Valved bovine jugular venous conduits for right ventricular to pulmonary artery reconstruction.

Various valved and nonvalved external right ventricle (RV) to pulmonary artery (PA) conduits have been used to palliate congenital heart anomalies. The ideal conduit has not been found. Reasons for conduit failures include stenosis, thrombosis, calcification of the valve or graft wall, and development of an obstructive peel. We evaluated valved and nonvalved conduits constructed from a glutaraldehyde preserved segment of bovine jugular vein. Bovine jugular conduits (n = 31), 10-13 mm in diameter, were implanted into weight-matched adult mongrel dogs using a standard closed heart technique. Valved conduits (VC, n = 17) were stented at the valve annulus with a Gore-Tex ring, whereas the nonvalved conduits (NC, n = 14) were stented at their midpoint. The proximal PA was tightly banded to 3 mm with a ligature. Cardiac output (CO) and hemodynamic gradients were measured at the time of insertion and 8 months postoperatively. Pulmonary artery angiograms were used to assess bovine jugular conduit regurgitation. All xenografts were evaluated by gross and histologic exam. Two dogs had conduits placed but died for reasons unrelated to the conduit before evaluation. Valved conduit leaflets showed thickening, insignificant thrombus deposition in the base of one or more cusps, and a mild degree of regurgitation as assessed by angiograms. Examination of the NC showed mild conduit thickening and a moderate-to-severe degree of regurgitation as assessed by angiograms. There was a significant difference observed in pulmonary outflow gradients between the VC (11 +/- 2 mm Hg) and NC (17 +/- 2 mm Hg) (p < 0.05), although neither group developed a hemodynamically significant gradient. On gross examination, VC ventricles displayed significantly less evidence of volume and pressure overload compared with the NC ventricle. Valved conduits demonstrated significantly less obstruction and regurgitation. The potential clinical advantages of bovine jugular conduits are their availability, potential durability evidenced by lack of early calcification, and the advantage of not requiring a proximal extension for the RV anastomosis. The presence of a durable and functional xenograft valve in valved conduits may prevent postoperative sequelae in some patients.

Bridging to transplant. Equal extended survival for patients undergoing LVAD support when compared with long-term medical management.

Implantation of ventricular assist devices (VADs) to support patients awaiting cardiac transplant has become an effective means of assuring that these critically ill patients survive to transplant. The authors undertook a retrospective analysis of 115 consecutive patients listed for cardiac transplant from January 1992 through June 1995. A VAD was implanted in 19 of these patients. Survival was calculated by intent to treat from the time of transplant listing through heart transplant, if it occurred. The analysis demonstrates that the patients who underwent implantation of a VAD as bridge to transplant had survival times similar to those of patients with medical management. These survival statistics demonstrate the utility of VADs as an effective means to bridge critically ill patients until a suitable donor organ becomes available. In addition, as previous studies have suggested for acute results, earlier implementation and better patient selection may lead to improved long-term survival.

Monocusp valve and transannular patch reconstruction of the right ventricular outflow tract: an experimental study.

Repair of congenital right ventricular outflow tract obstruction often requires reconstruction with a transannular patch to alleviate pulmonary stenosis. Post repair pulmonary insufficiency with right ventricular dilatation and volume overload may result and lead to acute or progressive right heart failure. The use of a monocusp valve has been proposed as a means to prevent this problem. Fresh pericardium is well known to fail clinically, leading to pulmonary insufficiency limiting mid- and long-term results. In a chronic dog model (147 +/- 34 days), three valve types were evaluated: 1) polytetrafluoroethylene (PTFE; n = 9), 2) fresh pericardium (PERI; n = 6), and glutaraldehyde fixed pericardium (GLU; n = 6). Hemodynamics, angiography, and echocardiography were performed at implantation and sacrifice. Gross and microscopic pathology were evaluated. No significant differences were found among the three groups with regard to stenosis as evaluated by echocardiography, measured right ventricular wall thickness, and hemodynamic pressure gradients across the valve. By echocardiography, both PTFE (1 of 9) and GLU (0 of 6) showed less regurgitation than PERI (5 of 6) (p < 0.05). This was confirmed by angiography. PTFE showed less neo-intimal hyperplasia, less thrombus formation, and less calcification than GLU or PERI (p = NS). The PTFE monocusp developed no prohibitive gradients, no early pathologic deterioration, and maintained competence compared with the GLU and PERI groups. Although continued investigation of long-term durability and competence of the PTFE monocusp valve is warranted, both PTFE and GLU values seem to demonstrate less regurgitation than the PERI monocusp valve in an adult dog model of right ventricular outflow tract reconstruction.

Coronary sinus adrenomedullin rises in response to myocardial injury.

Human adrenomedullin (ADM), a peptide comprising 52 amino acids, is a circulating hormone with vasodilator properties. We have evaluated its release by the heart following ischaemic myocardial damage, as indicated by elevated levels of the cardiospecific protein troponin-T (Tn-T) during cardiopulmonary bypass. ADM (pg/ml) and Tn-T (ng/ml) were measured in coronary sinus blood before and after aortic cross-clamp and in venous blood 6 h after surgery in 22 coronary-bypass patients. Based on the pre- and post-clamp Tn-T levels in the coronary sinus, the patients were divided into group I (no change; n=10) and group II (two times increase; n=12). Baseline ADM (362.7+/-106.2 and 303+/-58.7 pg/ml in groups I and II respectively; means+/-S.D.) and Tn-T (0.66+/-0.14 and 0.57+/-0.13 ng/ml respectively) levels were similar in both groups. In group I, the post-clamp ADM (317.6+/-80.8 pg/ml) and Tn-T (0.68+/-0.15 ng/ml) levels did not change significantly. In group II, the post-clamp ADM levels rose significantly above the baseline, mimicking the change in Tn-T (ADM, 541.4+/-89.4 pg/ml; Tn-T, 1.37+/-0.31 ng/ml; P=0.009). After 6 h, the systemic Tn-T levels were similar in both groups (2. 09+/-0.44 and 1.95+/-0.52 ng/ml in groups I and II respectively). We suggest that: (1) minor degrees of myocardial ischaemic damage result in release of ADM by the heart, and (2) ADM may play a protective role in the myocardium during an ischaemic insult. This suggests a possible therapeutic role for ADM in the management of intra-operative myocardial ischaemia.

Alternatives to human heart replacement.

The continuing and increasing discrepancy between the number of available donor hearts and the number of patients who might benefit from cardiac transplantation has prompted efforts in the development of xenotransplantation, mechanical assist devices, and cardiomyoplasty techniques. We briefly review recent work in these three fields. The results of experimental xenotransplantation between closely related species are improving slowly with currently available drugs, and clinical trials in this field may be possible in the near future. Implantable ventricular assist devices are also at a stage of development where permanent implantation is likely to be followed by a reasonable and worthwhile period of patient survival. With regard to cardiomyoplasty, steady progress is being made in clarifying exact indications and patient selection, as well as confirming the potential benefits.

Clinical trials of an intravenous oxygenator in patients with adult respiratory distress syndrome.

In patients with severe adult respiratory distress syndrome, mechanical ventilation may not be able to ensure gas exchange sufficient to sustain life. We report the use of an intravenous oxygenator (IVOX) in five patients who were suffering from severe adult respiratory distress syndrome as a result of aspiration, fat embolism, or pneumonia. IVOX was used in an attempt to provide supplemental transfer of CO2 and O2 and thereby reduce O2 toxicity and barotrauma. All patients were tracheally intubated, sedated, and chemically paralyzed and had a PaO2 < 60 mmHg when the lungs were ventilated with an FIO2 = 1.0 and a positive end expiratory pressure of > or = 5 cmH2O. The right common femoral vein was located surgically, and the patient was systemically anticoagulated with heparin. A hollow introducer tube was inserted into the right common femoral vein, and the furled IVOX was passed into the inferior vena cava and advanced until the tip was in the lower portion of the superior vena cava. IVOX use ranged from 2 h to 4 days. In this group of patients, IVOX gas exchange ranged from 21 to 87 ml x min-1 of CO2 and from 28 to 85 ml x min-1 of O2. One of the five patients survived and was discharged from the hospital. The IVOX transferred up to 28% of metabolic gas-exchange requirements. One patient with a small vena cava showed signs of caval obstruction. Three other patients demonstrated signs of a septic syndrome after the device was inserted.(ABSTRACT TRUNCATED AT 250 WORDS)