Management of patients supported on the Hemopump cardiac assist system

The Hemopump Cardiac Assist System is a relatively new intraarterial, axial-flow circulatory assist device that offers temporary left ventricular support to patients in refractory cardiogenic shock, without requiring major surgery for insertion. Use of the Hemopump is associated with a low complication rate. Device-related morbidity is extremely rare. Because the Hemopump is safe for use in community hospitals, the number of patients supported by this device is expected to increase. In this report, we present general guidelines for the care of patients supported by the Hemopump. We describe techniques for the management of afterload reduction, supravalvular dislodgement, device malfunction, ventricular ectopy, intracardiac shunting, and inflow cannula obstruction.

A community study of vitamin B12 and folate levels in the elderly

OBJECTIVE

To measure the prevalence of low serum vitamin B12, folate, and red cell folate levels and their relationship with other nutritional indices.

DESIGN

Prospective survey of elderly subjects using radioisotope dilution assays.

SETTING

Primary care medical center, Christchurch, New Zealand.

PATIENTS

257 elderly subjects (age 65 years and over), residing in their own homes or in residential homes, were randomly selected. Of these, 204 (79%) participated. The study population was comparable to the elderly population of New Zealand.

MAIN OUTCOME MEASURES

Vitamin B12, serum, and red cell folate levels.

RESULTS

The prevalence rates for low levels of serum vitamin B12, folate, and red cell folate were 7.3%, 1%, and 3.3%, respectively. The elderly cohort had lower vitamin B12 (P less than 0.001) but higher serum and red cell folate levels (P less than 0.001) than our normal reference range (age 18-65 years). Red blood cell folate levels showed positive correlations with nutritional indices and mental test scores. No correlations were found between vitamin B12 levels and diet or other nutritional indices.

CONCLUSIONS

Low folate levels in older people living at home are infrequent findings. In contrast low vitamin B12 levels are more common. Poor diet and undernutrition may contribute to low folate levels, but these factors are less important for the low B12 levels found.

Subclavian vein-to-right atrial bypass for symptomatic venous hypertension

A new surgical technique for bypassing subclavian vein thromboses in patients undergoing hemodialysis is presented. Subclavian vein stenosis or occlusion can occur after the use of temporary access catheters in subclavian vein dialysis. If this occurs in a patient with an arteriovenous access fistula of an ipsilateral upper extremity, venous hypertension, massive edema of the arm, and dysfunction of the access graft may result. In 2 patients with this condition, we successfully performed axillary vein-to-right atrial bypass, which resolved swelling and restored function of the access graft. This may be an appropriate surgical option for symptomatic venous hypertension in such patients.

Coronary artery bypass two years after orthotopic heart transplantation: a case report

Complete occlusion of the left anterior descending and right coronary arteries developed in a 58-year-old man 2 years after orthotopic heart transplantation. Because of his progressive shortness of breath, reversible myocardial ischemia, and decreasing ejection fraction, aortocoronary bypass was recommended. The operation was performed without complications, and his postoperative ejection fraction improved by more than 58%. In the past, when coronary artery disease developed in cardiac allografts, another transplant procedure was the only treatment option. Because of the limited donor hearts available today, new strategies are necessary for the treatment of cardiac allograft atherosclerosis.

Adjuvant native heart surgery during heterotopic heart transplantation: two case reports

The results of heterotopic heart transplantation may be further improved if repairs on native heart abnormalities are performed just before implantation of the allograft. Such procedures increase the potential for the recipient's own heart to recover function and, thus, to maintain circulation if the heterotopic heart malfunctions or fails. The native hearts of two of our patients, both women, showed signs of greater contractility and ejection after repair and were able to provide adequate circulatory support during periods of donor heart failure. The first patient required ventricular aneurysmectomy and coronary artery bypass grafting, and the second, native mitral valve repair. Moreover, when persistent ventricular fibrillation occurred in the donor heart of the first patient, a donor cardiectomy was performed, and the recipient heart functioned well thereafter. As more adjuvant operations are performed and the results evaluated, we may find that heterotopic operations would be suitable in a greater variety of heart transplant candidates.

Patent foramen ovale: a cause of hypoxemia in patients on left ventricular support

We describe 2 patients who experienced right-to-left shunting during support with a left ventricular assist device as a result of patent foramen ovale. In the first patient, the patent foramen ovale was not found until autopsy. In the second patient, fluctuations in continuous mixed venous oxygen saturations caused us to suspect a patent foramen ovale, which was confirmed with transesophageal contrast echocardiography. We promptly repaired the defect and this patient survived. When patients on assist devices experience unexplained arterial hypoxemia, a patent foramen ovale should be considered. If a patent foramen ovale is found, surgical correction should be done early.

Innominate artery occlusive disease: surgical approach and long-term results

We reviewed our experience with 54 patients who underwent innominate artery revascularization during a 10-year period. Their age range was from 16 to 75 years (mean, 49.8 years). The innominate artery alone was involved in 21 patients (39%); the remaining patients had additional arch vessel obstructions. Before operation, neurologic symptoms occurred in 25 patients (46%), arm ischemia related to claudication and microembolization occurred in 8 patients (14%), a combination of symptoms occurred in 17 patients (32%), and no symptoms were noted in 4 patients (8%). The extrathoracic approach to surgery was used in 16 patients (30%). Eleven of the 38 patients in whom the intrathoracic approach was used had endarterectomy of the innominate artery; in three of those, the procedure was combined with left common carotid endarterectomy. Bypass grafts were used in the other 27 patients undergoing procedures with an intrathoracic approach; in six of those, bypass was combined with carotid endarterectomy. No operative deaths occurred. Perioperative revascularization failure occurred in four cases; all of those patients underwent a second revascularization procedure, with a secondary patency rate of 100%. In four patients, late occlusion was noted at 6 months and at 1, 1.5, and 10 years. One patient had a permanent perioperative neurologic deficit in the distribution of the left carotid artery after a combined common carotid endarterectomy/innominate endarterectomy procedure. No neurologic deficits were directly related to the innominate artery territory. Long-term actuarial survival was 83% at 10 years. Early and late graft failures were related to inadequate inflow in bypass grafts, progression of distal disease in arteritis, and primary closure in endarterectomy.

Myocardium-sparing cannulation technique for left ventricular assist device support

The left atrium and the left ventricular apex are the most commonly used sites of inflow cannulation for postcardiotomy left ventricular support. A new cannulation technique that requires only an ascending aortotomy is introduced. This procedure can be undertaken with equipment present in any cardiac operating room and may prove to cause fewer complications than conventional cannulation techniques.

Extended support with a left ventricular assist device as a bridge to heart transplantation

The Heartmate-1000IP, an intracorporeal, pneumatically activated, pulsatile left ventricular assist device (LVAD) with textured blood-contacting surfaces, is undergoing clinical evaluation as a bridge to heart transplantation (HTx). During a 3 year period (January 1988 to April 1991), the authors evaluated 12 patients who required extended LVAD support (greater than 30 days) while awaiting HTx. Duration of support ranged from 31 to 233 days (mean, 117 days). LVAD performance was excellent, with average pump flow indices of 2.5-3.5 L/min/m2. Long-term antithrombotic therapy consisted of dipyridamole and aspirin in all except one patient who received only low-molecular-weight dextran. After the initial recovery period, prothrombin and partial thromboplastin times returned to baseline levels. Plasma-free hemoglobin levels averaged less than 10 mg/dl. One patient is currently receiving support (91+ days); the 11 other patients underwent successful HTx, with follow-up ranging from 7 to 36 months. The authors' cumulative experience with this LVAD totals more than 1,506 days of support (greater than 4 years) without evidence of any thromboembolic episodes. These results suggest that this LVAD provides an effective bridge to HTx for extended periods.

Quality of life in long-term survivors of the Hemopump left ventricular assist device

The courses of 10 patients (nine men and one woman; mean age, 54 years) were reviewed to determine the long-term results of treatment with the Hemopump (Nimbus Medical, Inc., Rancho Cordova, CA) left ventricular assist device. Indications for treatment were postcardiotomy cardiogenic shock (n = 8) and acute cardiac allograft rejection (n = 2). Two of the patients with postcardiotomy shock required a bridge to transplantation. At follow-up (mean, 21 months), eight patients were alive: four were in New York Heart Association Functional Class I and four were in Class II. None had long-term adverse effects that were attributable to the site of insertion (e.g., limb ischemia or infected groin wounds). All the patients considered themselves independent in their daily activities, and most of the patients were able to exercise and pursue hobbies. The Hemopump appears to offer long-term survival with an acceptable quality of life to a population of patients whose survival would have been highly unlikely otherwise.

Actin in the oomycetous fungus Phytophthora infestans is the product of several genes

Actin (ACT) in Phytophthora infestans is encoded by at least two genes, in contrast to unicellular and other filamentous fungi where there is a single gene. These genes (designated actA and actB) have been isolated from a genomic library of P. infestans. The complete nucleotide sequence of both genes has been determined. Unlike the actin-encoding genes (act) of other filamentous fungi, no introns are obvious in the coding region, a feature shared with the act genes of certain protists. Northern blotting and primer extension studies of the mRNA show that actA and actB are actively transcribed in mycelium, sporangia and germinating cysts but only at a low level in the case of actB. Both genes display bias in their codon usage. This is more extreme in actA. The deduced ACTB protein is strikingly similar to that of the Phytophthora megasperma actin and is more diverged from other actins than ACTA.

Heart transplantation in Jehovah's Witnesses. An initial experience and follow-up

More than 25 years of experience performing heart surgery on Jehovah's Witnesses has culminated in successful cardiac transplantation without administering blood products in five patients (mean age, 44.4 +/- 8.3 years) of this faith. The use of blood-conserving methods, iron supplementation, bone marrow-sparing maintenance immunotherapy, and brisk postoperative diuresis has added to the efficacy of cardiac transplantation in these patients. No perioperative deaths occurred, and early follow-up studies have shown that these patients have not been more susceptible to higher graft rejection rates due to the lack of pretransplant blood transfusions. As more Jehovah's Witnesses undergo heart transplantation in the future, comparison with other recipients who allow pretransplant blood transfusions may lead to a better understanding of rejection immunobiology. We conclude that cardiac transplants may be safely offered to Jehovah's Witnesses without fear of a uniformly poor outcome.

Rapid placement of the Hemopump and hemofiltration cannula

Hypervolemia, a potential complication in patients on ventricular assist device support, can be managed by use of continuous arteriovenous hemofiltration. The Hemopump, a new catheter-mounted, transaortic axial-flow ventricular assist device, and the vascular access catheter for the Diafilter-30 Hemofilter system, used in continuous arteriovenous hemofiltration, are both usually inserted by way of the femoral artery. Because placing two large catheters in the femoral artery of a patient with peripheral vascular disease can compromise circulation, a technique for placing them in the abdominal aorta was developed. Two patients have undergone combined Hemopump and hemofiltration treatment, and neither experienced complications. Such techniques may benefit more patients in the future, as the usefulness of the Hemopump is proved.

Use of potentially infected donor hearts for cardiac transplantation

Despite the nationwide shortage of heart donors, more patients, some of whom are critically ill, are being accepted as candidates for transplantation. Thus, on occasion, we have liberalized our donor criteria to meet the demand. We have recently transplanted 16 potentially infected donor hearts into critically ill recipients. Of these 16 donors, 7 had multiple positive blood cultures as follows: Streptococcus pneumoniae (3), Staphylococcus aureus (2), Klebsiella pneumoniae (1), and Enterobacter sp (1). Seven other donors were accepted despite high fevers (rectal temperature greater than 38.9 degrees C), leukocytosis (greater than 18 x 10(9)/L [greater than 18,000 cells/microL]), and pulmonary infiltrates with positive sputa (Enterobacter [3], Klebsiella pneumoniae [2], and Staphylococcus [2]). Two other donors with hepatitis B surface antigen positivity were deemed at high risk but were used because the recipients were in immediate need. Early mortality (less than or equal to 30 days) among the recipients was 3/16 (18.7%) with 1 patient dying of uncontrolled allograft rejection, 1 of hepatic failure, and 1 of Pseudomonas septicemia. Late mortality (greater than 30 days after operation) occurred in 6 patients: 2 patients died of hepatic failure, 3 died of graft atherosclerosis, and 1 died of iatrogenic hemorrhage after a liver biopsy. Only 1 patient died of infection unrelated to that of the donor, and the other patients had no infectious complications resulting from the organisms identified in their respective donors. Use of potentially infected donor hearts resulted in surprisingly few infectious complications in this group of recipients. This practice can be safe and should be considered when other options are unavailable.

Treatment of cardiac allograft failure by use of an intraaortic axial flow pump

Since April 1988 we have used the Hemopump device, a new means of circulatory support, to successfully treat three orthotopic heart transplant recipients with biventricular failure refractory to conventional therapy. The Hemopump device is a 21F catheter-mounted, transvalvular, intraaortic axial flow pump. Power to the pump is percutaneously transmitted from an external electromechanical drive console by a flexible drive cable. We first used the pump in a 61-year-old man in whom severe steroid-resistant rejection developed 28 days after heart transplant, resulting in cardiogenic shock (cardiac index less than 2.0 L/min/m2) despite maximal inotropic support. In the second case a 49-year-old man with no evidence of pulmonary hypertension sustained cardiac arrest 2 hours after heart transplant, necessitating open chest massage and emergency cardiopulmonary bypass. The third patient was a 9-year-old boy in whom rejection developed 5 months after heart transplant, resulting in congestive heart failure that was unresponsive to maximal medical therapy. The device was implanted by way of the femoral artery approach in the first case, the ascending aorta in the second, and the distal abdominal aorta in the third. Duration of support was 46 hours, 65 hours, and 6 days, respectively. Increased blood flow provided by the pump ranged from 2 to 4 L/min. No device-related complications, such as hemolysis, infection, or thromboembolic events, occurred. All patients recovered normal heart function and were weaned from the device. The first patient is well after 12 months. The second patient died of metastatic lymphoma at 2 months, and the third died of Pseudomonas pneumonia after 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Extension of donor criteria in cardiac transplantation: surgical risk versus supply-side economics

To combat the continuing shortage of ideal donor hearts, we have used cardiac allografts from high-risk donors for critically ill recipients. We defined high-risk donor variables as age greater than 40 years, systemic (noncardiac) infection, cardiopulmonary resuscitation greater than 3 minutes, ischemic time longer than 5 hours, weight more than 20% less than that of the recipient, and requirements for high doses of inotropes. Of the 305 donors we have used, 73 (23.9%) have been high-risk, with 59/73 (80.8%) exhibiting one variable, 12/73 (16.4%) exhibiting two variables, and 2/73 (2.7%) exhibiting three variables. No correlation was found between the number of donor variables and a poor postoperative result. No infectious complications occurred in 17 patients receiving hearts from potentially infected donors. Hospital mortality rates (30 day) for recipients of high-risk donor versus non-high-risk donor hearts were 8.2% and 6.9%, respectively (not significant). The 1-, 6-, and 12-month actuarial survival rates were 91.7%, 81.2%, and 75.9% for the high-risk donor group and 93.5%, 80.3%, and 77.8% for the non-high-risk donor group (not significant). Among survivors with high-risk donor hearts, mean left ventricular ejection fractions were 0.54 +/- 0.08 at 3 months, 0.55 +/- 0.08 at 1 year, and 0.54 +/- 0.09 at 2 years after transplantation. These results suggest that accepting less than ideal donor hearts can be safe and might be considered when better options are not available.

Nutritional assessment of patients with extended left ventricular assist device support

The nutritional status of nine patients with end-stage heart disease who were supported by a left ventricular assist device (LVAD) for more than 30 days while awaiting cardiac transplantation was evaluated. Nutritional status was indicated by the following scale: 0-2, adequate nourishment; 3-5, moderate malnourishment; greater than 5, severe malnourishment. This scale was based on serial assessments of albumin, transferrin, total lymphocyte count, percentage of ideal body weight, midarm circumference, triceps skinfold, and arm muscle circumference. Each variable was compared with established standards before implantation and before transplantation times and assessed 1 point if less than the normal value and 0 points if within the normal range. At the time of LVAD implantation, 5 patients had a score of 0-2, 3 patients had a score of 3-5, and 1 patient had a score greater than 5. At the time of cardiac transplantation, 7 patients had a score of 0-2, 2 patients had a score of 3-5, and no patients had a score greater than 5. The patients who were able to meet at least 50% of their daily caloric and protein requirements by oral intake alone were noted. At LVAD implantation, only 2 patients (22%) met this requirement; however, 6 patients (67%) met this requirement at the time of cardiac transplantation. All 9 patients underwent cardiac transplantation, and 8 survived. Thus, it appears that extended LVAD support and maintenance of hemodynamic stability allow patients to regain the desire and ability to achieve adequate nutritional status, which may considerably reduce their perioperative transplant risks.

Improved survival after Hemopump insertion in patients experiencing postcardiotomy cardiogenic shock during cardiopulmonary bypass

Immediate placement of a Hemopump (HP) ventricular assist device was undertaken in nine patients (seven men, two women) after other attempts at weaning from cardiopulmonary bypass (CPB) after coronary bypass surgery had failed. All nine patients (100%) were successfully weaned from CPB, and six (63.3%) gradually improved enough to permit removal of HP support. Five (83.3%) of the six who were weaned from CPB survived beyond hospital discharge. HP support was evaluated in terms of vital organ function, incidence of complications, and clinical outcome. In both survivors (S) and nonsurvivors (NS), serial hemodynamic measurements were taken. Although there were few differences in hemodynamic parameters between groups at 4 hr, by 24 hr the S group had markedly improved cardiac index, Glasgow Coma Scale, urinary output, and pulse pressure and required far less inotropic support than did the NS group. All four patients who required high dose inotropic agents to maintain acceptable end-organ perfusion on HP support died; three were unable to tolerate weaning from the HP, and all died within 72 hr of surgery because of ineffective myocardial recovery. None of the survivors required additional early inotropic augmentation. Renal perfusion appeared to be well maintained, even with mean arterial pressures below 60 mmHg during HP support. There were no episodes of hemolysis, infection, or limb ischemia in either group. Thus, the Hemopump provided excellent circulatory support for those patients who could not be weaned from CPB by traditional methods.

First human use of the Hemopump, a catheter-mounted ventricular assist device

The Hemopump, a catheter-mounted, temporary ventricular assist device, consists of an external electromechanical drive console and a disposable, intraarterial axial-flow pump (21F). Power is transmitted percutaneously to the pump by a flexible drive shaft within the catheter. The device is positioned in the left ventricle by way of the femoral artery approach or through the ascending aorta. Blood is drawn from the left ventricle through the transvalvular inlet cannula and pumped into the aorta. As of December 1988, the Hemopump had successfully supported the circulation of 7 patients (5 men, 2 women) ranging in age from 44 to 72 years (mean age, 59 years) and suffering from cardiogenic shock (cardiac index less than 2.0 L/min/m2). Indications for use included failure to be weaned from cardiopulmonary bypass in 4 patients, acute myocardial infarction in 1, severe cardiac allograft rejection in 1, and donor heart failure in 1. Duration of support ranged from 26 to 113 hours (mean, 66 hours). Although 5 patients demonstrated transient hemolysis, none experienced infection, thrombosis, or vascular injury. Hemodynamic variables improved in all patients during support by the device. As of December 1988, 5 of the 7 patients were alive more than 30 days after support had been discontinued, and 3 of these patients were discharged from the hospital. On the basis of our initial clinical results, the Hemopump, which does not require a major surgical procedure for insertion, provides effective, temporary circulatory support in patients with potentially reversible cardiac failure.

Risk factors for development of accelerated coronary artery disease in cardiac transplant recipients

Allograft coronary artery disease (CAD) is the major determinant of long-term survival following heart transplantation (HTx). In a group of 210 heart transplant recipients, we diagnosed CAD in 54 (27.1%) by coronary angiography, postmortem examination or examination of the transplanted heart at the time of retransplantation. Retrospective analysis of potential risk factors for the development of CAD was performed for both immunological (rejection pattern, immunosuppressive therapy, cytomegalovirus [CMV] infection), and nonimmunological (hyperlipidemia, smoking, hypertension, diabetes mellitus, obesity) risk factors. The total number of rejection episodes correlated significantly with the occurrence of CAD (P less than 0.05), showing that patients who experienced two or more rejection episodes had an incidence of CAD of 40%, as opposed to a 23% incidence in patients who experienced no rejection. A composite rejection score derived from multivariate regression analysis of the severity, frequency, and timing of acute cardiac rejection episodes was found to correlate with the development of CAD (P less than 0.05). Postoperative arterial hypertension also correlated significantly with the onset of CAD (P less than 0.01), with a 92.6% incidence of hypertension in the group with CAD versus 76.3% in the group without CAD. Smoking after transplantation correlated significantly with the occurrence of CAD (P less than 0.05). There was no significant correlation with other analyzed factors in this group of patients. In this review, the development of CAD after heart transplantation correlated with treated allograft rejection. Aggressive treatment of hypertension and cessation of smoking may contribute to alleviation of this serious complication.

Concomitant donor heart coronary artery bypass grafting during orthotopic heart transplantation

A 54-year-old diabetic woman with severe cardiomyopathy was placed on our heart transplant candidate list. The patient's condition rapidly worsened and a potential donor-a 45-year-old man whose blood was compatible with that of our patient-was located. Because of the donor's age, coronary arteriography was done, and stenosis in the midleft anterior descending coronary artery was identified. Since the patient's status was critical, the donor heart was accepted despite the presence of stenosis. We used the recipient's internal mammary artery to bypass the stenosis in the left anterior descending artery of the donor heart after performing a standard orthotopic heart transplant. The patient's postoperative course has been relatively free of complications, and the cardiac allograft has functioned well. The early results in this patient are comparable to those of our historical transplant control group. We suggest that the impact of donor organ shortages may be lessened by use of innovative procedures and extended donor selection criteria.

Implantation techniques for the Hemopump

Techniques for implantation of the Hemopump, an intraarterial, axial-flow circulatory assist device, are described. The Hemopump, which is currently undergoing clinical investigation, has been used successfully to treat patients experiencing profound left ventricular failure in a variety of clinical situations, including postcardiotomy shock, acute myocardial infarction, cardiac allograft rejection, and cardiac allograft failure.

Effect of prior cardiac surgery on survival after heart transplantation

We conducted a retrospective analysis of 182 adult orthotopic heart transplant patients who underwent operations at our institution between July 1982 and October 1987 to determine whether prior cardiac operation affects survival. Group I included the 72 patients (39.6%) who had undergone a previous cardiac operation or operations and group II, the 110 (60.4%) who had not. The mean age of the patients in group I was 52.1 +/- 8.1 years and in group II, 46.1 +/- 10.2 years (p less than 0.01). The incidence of ischemic heart disease was 86.1% in group I and 29.1% in group II (p less than 0.01). All patients received cyclosporine-based immunosuppression. More patients in group I than in group II required reoperation for bleeding after transplantation: 18 (25.0%) versus 9 (8.2%) (p less than 0.01). The actuarial 1-year and 3-year survival rates were 77.6% and 66.5%, respectively, for group I and 77.1% and 66.3%, respectively, for group II. Because both groups had similar survival rates, we believe that prior cardiac operation in heart transplant recipients does not compromise long-term survival.