Walter E. Pae

Ventricular-Assist Pumping in Patients with Cardiogenic Shock after Cardiac Operations

A ventricular-assist pump was used to support the circulation in eight patients who could not be separated from cardiopulmonary bypass after open-heart operations. In five patients with left ventricular failure, the systemic circulation was maintained with pumping from the left atrium to the aorta for 7.0 +/- 1.8 days (mean +/- S.E.M.); three of these patients were well four to 17 months after surgery. In two patients with biventricular failure, right and left ventricular bypass supported the circulation, but neither patient survived. One other patient had isolated right ventricular failure; pumping from the right atrium to the pulmonary artery maintained the pulmonary circulation for 2.2 days. This patient lived for 18 months. Use of the ventricular-assist pump in our patients provided complete support of the systemic or pulmonary circulation or both. Profoundly depressed ventricular function is potentially reversible if technical problems in employing the pump can be avoided.

Heterotopic prosthetic ventricles as a bridge to cardiac transplantation. A multicenter study in 29 patients

Heterotopic prosthetic ventricles were used to support the circulation in 29 candidates for heart transplantation who were expected to die before procurement of a donor heart. Twenty-one of these patients (average age, 36 years) underwent successful transplantation after 8 hours to 31 days of circulatory support. The other eight patients died because their condition could not be stabilized for transplantation, despite restoration of blood flow. Fourteen patients received biventricular support; 15 received only left ventricular support, with pharmacologic assistance of right heart function. Before transplantation, blood flow from the left prosthetic ventricle averaged 2.8 +/- 0.4 liters per minute per square meter of body-surface area, and from the right prosthesis 2.4 +/- 0.4 liters, as compared with an average flow of 1.6 +/- 0.5 liters per minute per square meter before implantation. Of the 21 patients who received heart transplants, 20 were discharged from the hospital after a median of 31 days. Nineteen patients were alive at 7 to 39 months, and 11 of the first 12 were alive at one year. We conclude that heterotopic placement of prosthetic ventricles as a bridge to transplantation provides an effective method of temporarily supporting cardiac function in critically ill patients without removing the natural heart. The early survival rate after transplantation is similar to that with elective cardiac transplantation.

Aortic valve replacement and combined aortic valve replacement and coronary artery bypass grafting: predicting high risk groups

To determine which groups of patients are at highest risk for operative or late mortality, 259 consecutive patients who underwent operation between 1978 and 1984 were studied; 170 underwent aortic valve replacement and 89 underwent aortic valve replacement combined with coronary artery bypass grafting. Multivariate analysis of risk factors selected emergency operation and patient age older than 70 years as the strongest predictors for operative death. Although patients having aortic valve replacement and coronary artery bypass grafting had a higher operative mortality rate (13.5 versus 3.5%), the combined operation had no independent predictive effect on early or late results. At a mean follow-up time of 48 months after surgery, 72% of the survivors of operation were living, 10% were lost to follow-up and 18% were dead. Seventy-seven percent of long-term survivors were in New York Heart Association functional class I or II. The incidence of thromboembolism, paravalvular leak, bacterial endocarditis and hemorrhage each occurred at a rate of less than 1% per patient-year. The factors associated with late death were preoperative age, male sex, left ventricular end-diastolic pressure, cardiac index and functional class. Despite an increase in operative mortality, patients undergoing emergency operation were not at higher risk of late death. Operative mortality is concentrated among several high risk groups. For patients undergoing elective operation, operative mortality is low, especially if the patient is less than 70 years old. Late results are good for all groups of patients undergoing operation, including those who are at greater risk of dying at operation.

The LionHeart LVD-2000 : a completely implanted left ventricular assist device for chronic circulatory support

Management of patients with end-stage cardiac disease remains a vexing problem. Limitations in medical management and a fixed supply of donor organs for cardiac transplant have a continued impact on this growing population of patients. Mechanical circulatory support has proved very successful as a means of bridging patients to cardiac transplant when all medical options have been exhausted. The development of a chronic system of circulatory support has been underway at the Pennsylvania State University for nearly 30 years. These efforts have been recently merged with the industrial partnership with Arrow International toward the development of the LionHeart LVD-2000 (Arrow International, Reading, PA) completely implanted left ventricular support system. We present an overview of the system, details of implantation, a review of preclinical studies, and a synopsis of the first European implants. Early results have demonstrated the system to be safe, effective, and reliable. Transcutaneous energy transmission and the compliance chamber have been validated.

The RECOVER I: A multicenter prospective study of Impella 5.0/LD for postcardiotomy circulatory support

OBJECTIVES Cardiogenic shock after cardiac surgery is accompanied by a high mortality rate. Early institution of hemodynamic support with a versatile, easy to insert left ventricular assist device might help bridge patients to recovery or to the next therapy, and improve the outcomes. METHODS Patients developing cardiogenic shock or low cardiac output syndrome after being weaned off cardiopulmonary bypass were enrolled in a prospective single-arm feasibility study (RECOVER I). The primary safety endpoint was the frequency of major adverse events (death, stroke) at 30 days or discharge, whichever was longer. The primary efficacy endpoint was survival of the patient to implementation of the next therapy, which included recovery at 30 days after device removal and bridge-to-other-therapy. RESULTS Sixteen patients provided informed consent and were enrolled in the study. Hemodynamics improved immediately after the initiation of mechanical support: cardiac index, 1.65 versus 2.7 L/min/m(2) (P = .0001); mean arterial pressure, 71.4 versus 83.1 mm Hg (P = .01); and pulmonary artery diastolic pressure, 28.0 versus 19.8 mm Hg (P < .0001). The pump provided an average of 4.0 ± 0.6 L/min of flow for an average duration of 3.7 ± 2.9 days (range, 1.7-12.6). The primary safety endpoint occurred in 2 patients (13%; 1 stroke and 1 death). For the primary efficacy endpoint, recovery of the native heart function was obtained in 93% of the patients discharged, with bridge-to-other-therapy in 7%. Survival to 30 days, 3 months, and 1 year was 94%, 81%, and 75%, respectively. CONCLUSIONS The use of the Impella 5.0/left direct device is safe and feasible in patients presenting with postcardiotomy cardiogenic shock. The device was rapidly inserted, enabled early support, and yielded favorable outcomes.

Initial experience with CentriMag extracorporal membrane oxygenation for support of critically ill patients with refractory cardiogenic shock

BACKGROUND Cardiogenic shock refractory to conventional therapy has very high mortality and limited support options. New technology with peripherally inserted CentriMag (Levitronix LLC, Waltham, MA) extracorporal membrane oxygenation (ECMO) may have the potential to significantly improve survival in these critically ill patients. Outcomes of the first 10 patients to receive this device at our institutions are presented. METHODS Patients were identified by their primary physicians and evaluated by our Mechanical Circulatory Support Team. CentriMag ECMO was initiated at the bedside using sterile percutaneous cannulation of femoral vessels. Patients were admitted to the Heart and Vascular Intensive Care Unit, with care managed by regular nursing staff with special training. RESULTS The patients (5 men, 5 women) were a mean age of 45 +/- 18 years, had a mean left ventricular ejection fraction of 30%, and a mean lactate level of 9 mmol/liter. All patients met criteria for shock refractory to medical therapy, but the etiology varied. Average duration of ECMO support was 5.8 +/- 4 days. Survival was 60%. There were no major complications directly related to the device and no equipment malfunctions. CONCLUSIONS The peripherally inserted CentriMag ECMO was easy to insert, functioned without mechanical error, and significantly reduced expected mortality in critically ill patients. Further research will be necessary to develop standardized algorithms and gain more experience, but this new technology has promising potential.

Worldwide surgical experience with the Paracor HeartNet cardiac restraint device

OBJECTIVE An elastic ventricular restraint device has been developed for patients with heart failure who remain symptomatic despite treatment with standard therapies. The safety and efficacy of this device are under clinical investigation. Six-month data for the first 51 patients treated worldwide are reported. We hypothesize that the Paracor HeartNet device (Paracor Medical, Sunnyvale, Calif), placed through a minithoracotomy in patients with severe dilated cardiomyopathy, improves clinical and functional status. METHODS Fifty-one patients with an ejection fraction of 35% or less, with a New York Heart Association class II or III, and receiving optimal medical therapy for at least 3 months, were selected at 15 sites (3 in Europe, 12 in the United States) to undergo implantation of the HeartNet device through a minithoracotomy. Patients were evaluated at baseline and at 6-month follow-up by echocardiography, the 6-minute walk test, cardiopulmonary exercise testing (partial oxygen pressure in mixed venous blood), New York Heart Association class, and (in the United States) the Minnesota Living with Heart Failure questionnaire. RESULTS The average age was 52 years (30-73 years), with a preponderance of men and nonischemic cause of heart failure. Implantation was accomplished in 50 of 51 patients (98%). Adverse events included 2 in-hospital deaths secondary to pulmonary complications (4%), additional pulmonary complications in 7 patients (14%), arrhythmia in 14 patients (27%), epicardial laceration in 2 patients (4%), and empyema in 1 patient (2%). Six-month data demonstrated significant improvement in the 6-minute walk test (+65.7, P = .002) and Minnesota Living with Heart Failure scores (-15.7, P = .002) and improvement in echocardiographic findings. CONCLUSION The Paracor HeartNet device can be reliably implanted in patients with heart failure and marked reduction of left ventricular function. These data suggest a functional and clinical benefit, with a trend toward reverse remodeling, and support the conduct of a randomized controlled pivotal trial.

Ventricular assist devices and total artificial hearts: A combined registry experience

Data submitted voluntarily to the combined registry for the past 6 years on the use of ventricular assist devices for postcardiotomy cardiogenic shock in 965 patients and for circulatory support in conjunction with cardiac transplantation in 544 patients were analyzed. Of those patients whose ventricular function was expected to recover, approximately 45% were weaned from circulatory support and 25% were discharged from the hospital. Weaning status and hospital discharge were not different regardless of the type of original operative procedure or the pump design used. In the potential cardiac transplant group, 69% ultimately underwent transplantation and 66% were discharged from the hospital. The demographics (age and sex) of this group parallel those of patients undergoing isolated cardiac transplantation, and the 1- and 2-year survival estimates for patients requiring only univentricular support were equivalent to those of patients having isolated orthotopic cardiac transplantation. Ventricular assist devices are able to provide reasonable and safe circulatory support in both the postcardiotomy cardiogenic shock and the bridge-to-transplantation applications.

Preliminary experience with the lionheart left ventricular assist device in patients with end-stage heart failure

BACKGROUND The Arrow LionHeart LVD 2000 left ventricular assist device is the first fully implantable system designed for destination therapy. We report on 2 years of experience with this device, which we implanted for the first time in October 1999. METHODS Since October 1999, 6 male patients between 55 and 69 years of age (mean 65 +/- 6 years) have received the device at our center; all were in New York Heart Association functional class IV and ineligible for heart transplantation. RESULTS All surgical procedures were uneventful, with a timely extubation in 5 of 6 patients. Duration of support was 17 to 670 (mean 245 +/- 138) days, with a cumulative experience of 4.5 years. Three patients recovered to be discharged from hospital under support and are long-term survivors. Three patients died 17, 31, and 112 days after implantation from multiple organ failure without being discharged to their homes. The survival rate is 50% after 18 months. There were no major system-related problems or any device-related infections, which are otherwise commonly found among vertricular assist device patients. CONCLUSIONS Our preliminary experience demonstrates the reliability and efficacy of the different parts of the system. Nevertheless, further sophistication is needed to reduce the size of its components, which so far still constitutes a limiting factor.

Reduction of myocardial infarct size: comparison between left atrial and left ventricular bypass.

A controlled study was undertaken to quantitate and compare the effect of left ventricular bypass (LVB) and left atrial bypass (LAB on left ventricular infarct volume (LVIV). After baseline studies, the left anterior descending coronary artery in each of 30 mongrel dogs was ligated 1-1.5 cm from its origin. After baseline ischemic studies, control dogs (group 1--10 dogs), LAB dogs (group 2--10 dogs), and LVB dogs (group 3--10 dogs) were monitored for four hours. Final infarct size was determined by the nitroblue tetrazolium staining technique. Heart rate, mean arterial pressure, and total systemic flow (TSF) showed no significant difference between control and left heart bypass groups. In group 1, the LVIV was 27.7 +/- 6.5 g/100 g left ventricle (LV). In group 2, left heart bypass (LHB) flow was 90 +/- 4% of TSF. The pressure time index (PTI) was 2845 +/- 52 mm Hg-sec/min. The PTI demonstrated no significant difference from cntrols. In group 2, LVIV was 22.5 +/- 6.0 g/100 g LV. LVIV was reduced 18.8% from controls (p less than 0.08). In group 2, LHB was complete. Left ventricular decompression (group 3) resulted in a PTI of 328 +/- 76 mm Hg-sec/min. The PTI was significantly different (p less than 0.001) from groups 1 and 2. The LVIV was 12.6 +/- 5.1 g/100 g LV. LVIV was reduced 54.5% from controls (p less than 0.001) and 44.0% from group 2 (p less than 0.001). These results suggest that LVB may be useful, not only in supporting the circulation in the patient with myocardial infarct and cardiogenic shock, but also in limiting infarct size.