Robert S. Litwak

Use of a Left Heart Assist Device after Intracardiac Surgery: Technique and Clinical Experience

A left heart assist device (LHAD) has been employed in 14 patients. All had advanced heart disease and were in low cardiac output after repair, such that they could not be separated from cardiopulmonary bypass despite prolonged support and adjuvant therapy, including drugs, pacing, and use of intraaortic balloon counterpulsation whenever possible. Apart from special cannulas, the equipment necessary for the LHAD is widely available. An asset of the system (left atrial-ascending aorta bypass of the left ventricle) is that it may be terminated without reentering the thorax to remove the cannulas. This is accomplished with precisely fitting obturators that obliterate the cannula lumens and allow the tubes to be permanently implanted. This concept is believed important since critically ill patients requiring support are precisely those in whom added risk would be imposed by a second operation. Of the 14 patients who have had intraoperative and postoperative support (up to 6.8 days), 9 were weaned from the device and 6 were dismissed from the hospital. Four patients remain alive and are improved, the longest at 22 months since operation. The favorable performance of the LHAD suggests that it may prove useful either when intraaortic balloon counterpulsation cannot be successfully deployed or when it has failed to achieve hemodynamic stability.

Long-term follow-up of patients with cardiac pacemakers∗

Abstract One hundred and ninety patients have had implantation of intracorporeal electronic cardiac pacemakers at the Mount Sinai Hospital between September 1962 and May 1967. Transthoracic units were employed in 91 cases (mean follow-up interval 38.5 mo.), and transvenous pacers were used in 99 patients (mean interval 9.9 mo.). One hundred reoperations have been performed, 74 in the transthoracic group and 26 in the transvenous series. Analysis of failure rates at six months following surgery discloses 25 reoperations in 91 patients with transthoracic pacemakers (27%) and 17 reoperations in 64 with transvenous catheter pacemakers (27%). However, the magnitude of the operative procedures has been less in the latter group. There have been 35 deaths, 25 in the transthoracic series and 10 in the transvenous series, although 30-day mortality has been 5 and 3 per cent, respectively. Six month mortality is 15 per cent for the transthoracic pacemaker group and 8 per cent for the transvenous series. Most patients have died from diseases unassociated with their heart block. Comparison of mortality rates for patients with Stokes-Adams syndrome treated medically and surgically reveals that substantial improvement in prognosis has been achieved by the use of implantable electronic pacemakers.

A Decade of Experience with a Left Heart Assist Device in Patients Undergoing Open Intracardiac Operation

Over a decade has elapsed since the first clinical application of our left heart assist device (LHAD). The basic concepts underlying its development evolved from prior experience in which, given adequate support time, less than total left heart bypass (LHB) was found to result in gradual improvement of depressed left ventricular function. Hence, the long-held view that functional recovery of the heart could occuronlyunder conditions of total LHB seemed unsupportable by clinical realities. As a result, a simple LHAD was devised. Requiring only special silicone elastomer cannulas, the system uses a roller (or other continuous flow) pump and diverts blood from the left atrium to the ascending aorta. We believe a major asset of the system is the ability to separate the patient subsequently from the LHAD without need to re-enter the thorax. This is accomplished by permanently occluding each cannula lumen with an obturator, thereby allowing the biocompatible cannulas to remain permanentlyin situ.To date, 27 patients have undergone LHAD support. Of 18 patients who could be separated from the device, half (9) were discharged from the hospital. Seven remain alive and well, the longest now more than 10 years after the operation. Although rarely needed, broadening operative indications in patients with severely compromised left ventricular function suggests that there will be continued need for a method of LHB for the foreseeable future.RésuméIl sest passé plus dune décénie depuis la première application clinique de notre pompe dassistance gauche. Le concept de base qui a soutendu sa conception pratique a évolué depuis lexpérience clinique initiale dans laquelle une assistance totale du coeur gauche—plus quune assistance pendant un temps donné—avait montré une amélioration progressive des fonctions ventriculaires gauches altérées. A partir de ces données il est apparu irréalisable au plan clinique dans une perspective à long terme que la récupération fonctionnelle du coeur ne puisse survenirseulement que dans des conditions dassistance totale du coeur gauche. Par conséquent, une simple pompe dassistance du coeur gauche a été imaginée. Le système, ne nécessite que des canules spéciales en silicone raccordées à une pompe à galet (ou un autre type de pompe à débit contenu) qui détournent une partie du sang de loreillette gauche vers laorte ascendante. Nous croyons quun des éléments majeurs de ce système réside dans le fait quil soit possible de sevrer le malade de cette assistance gauche sans avoir besoin douvrir le thorax. Ceci est réalisé en obturant de facon permanente la lumière de chaque canule, et par conséquent en laissant ces canules biocompatibles in situ de façon permanente.Jusquà ce jour, 27 malades ont été placés sous assistance gauche. Des 18 malades qui ont pu être sevrés de cette assistance, la moitié (9) ont pu sortir de lhôpital. Sept dentre eux sont vivants et vont bien. Le plus long recul est de plus de 10 ans après lintervention.Bien que rarement nécessaires, des indications opératoires plus larges chez les malades ayant des fonctions ventriculaires gauches gravement compromises, suggèrent que le besoin dune méthode dassistance gauche persiste encore.ResumenHa transcurrido una década desde la primera aplicación clínica de nuestro aparato de asistencia mecánica del corazón izquierdo (AMCI). Los conceptos básicos que fundamentaron su desarrollo evolucionaron a partir de experiencia clínica previa en la cual, dado un tiempo de soporte adecuado, se encontró que una exclusión parcial del corazón izquierdo resultaba en una mejoría gradual de la deteriorada función del ventrículo izquierdo. Por lo tanto, la arraigada creencia de que la recuperatión funcional del corazón no podría ocurrir sino bajo condiciones de exclusión total del corazón izquierdo apareció insostenible a la luz de la realidad clínica. Como resultado, se diseñó un aparato simple de asistencia de corazón izquierdo. El sistema solo requiere cánulas elastómeras especiales de silicón y utiliza una bomba de rodillo (o cualquiera otro tipo de flujo continuo) para desviar la sangre de la aurícula izquierda a la aorta ascendente. Creemos que una ventaja mayor del sistema es la capacidad de separar al paciente del AMCI sin necesidad de un reingreso al tórax. Se logra esto mediante la oclusión permanente de cada cánula por un obturador, lo cual permite que las cánulas biocompatibles puedan permanecer indefinidamente in situ.Hasta la fecha 27 pacientes han recibido soporte con la AMCI. De 18 pacientes que pudieron ser desahijados del aparato, la mitad (9) pudieron ser dados de alta del hospital. Siete sobreviven en buen estado, el de mayor supervivencia con más de 10 años después de la operación. Aun cuando raramente necesario, la ampliación de las indicaciones quirúrgicas en pacientes con severo compromiso de la función ventricular izquierda hace pensar que se mantendrá la necesidad de un método de exclusión parcial del corazón izquierdo en el futuro inmediato previsible.

ELECTIVE OPEN HEART SURGERY IN MITRAL STENOSIS: EXPERIENCE WITH A STAND-BY PUMP OXYGENATOR.

Abstract Primary surgery for mitral stenosis employing pump-oxygenator stand-by was performed in 42 patients. All operations were instituted as closed procedures, but whenever a satisfactory result could not be achieved, open operation with extracorporeal circulation (50 per cent hemodilution with standard 1 to 5 day old buffered banked blood) was immediately instituted. Twenty-five patients had closed operation alone. There was one operative death and no subsequent mortality. There was good leaflet pliability without calcification, fibrosis or regurgitation in 16 of these. The left atrial-left ventricular mean diastolic gradient averaged 10.7 mm. Hg before commissurotomy and 0.9 afterward. Nine patients had varying degrees of leaflet immobility, fibrosis and calcification, but open operation was not elected because of advanced age or coexisting medical problems. In this group, the left atrial-left ventricular mean diastolic gradient averaged 15.6 mm. Hg before commissurotomy and 3.9 afterward. Preoperative radiologic detection of calcification, regardless of degree, uniformly indicated that a satisfactory closed commissurotomy could not be accomplished. Open operation was performed in the majority. In 17 cases mitral valve morphology prevented satisfactory closed surgery, and open repair was immediately performed utilizing the stand-by pump-oxygenator. In all cases, the valves were heavily calcified or fibrotic. Debridement and plastic procedures on the deformed mitral valves under direct vision did not achieve satisfactory mobilization. Mitral valve excision and replacement with a Starr-Edwards prosthesis was done in all patients. Sixteen of the 17 patients who underwent valve replacement are alive and well. Anatomic and hemodynamic restoration of mitral valve function can be predictably accomplished by closed operation in patients whose valves have retained their intrinsic flexibility. The availability of a stand-by pump-oxygenator has permitted immediate application of open repair when necessary.

The role of bradycardia in the retention of sodium and water in complete heart block with and without heart failure in human beings

Abstract 1. 1. The relative contribution of bradycardia in causing heart failure in patients with complete and advanced heart block was assessed by studying the effect of increasing the cardiac rate by an internal pacemaker. 2. 2. The ability to excrete graded loads of sodium was measured in 4 patients with complete or advanced heart block. Maximal sodium excretory capacity and the presence or absence of heart failure, after the stress of sodium-loads, during bradycardia, and after increasing the cardiac rate, were determined. 3. 3. One patient who had no heart failure despite cardiac rates between 30 and 40 could ingest and excrete 26 Gm. of sodium chloride daily without the development of heart failure. A second patient without heart failure had a maximal excretory capacity of 16 Gm. daily and exhibited symptoms and signs of heart failure with intakes in excess of this quantity. In the other 2 patients with heart failure at the time of hospitalization, maximal daily excretory capacity for sodium was 35 to 55 mEq. 4. 4. After cardiac rates were increased to normal with an artificial pacemaker, maximal excretion of sodium increased significantly. In the 2 patients with heart failure at slow idioventricular rates, the decompensation was eliminated or ameliorated. Although the maximal excretion of sodium was increased, it was still below normal in the latter 2 patients. 5. 5. The glomerular filtration rate was diminished in varied degree and correlated with the capacity for sodium excretion and the presence of absence of heart failure in each of the patients.

Case 1—1993 The role of erythropoietin in Jehovah's Witnesses requiring cardiac surgery

Case 1 * A 46-year-old female Jehovah’s Witness presented for cardiac surgery. She had a history of rheumatic heart disease, which consisted of moderate-to-severe aortic regurgitation and mild aortic stenosis, moderate-to-severe mitral regurgitation, severe tricuspid regurgitation, and pulmonary hypertension. The patient was also in chronic atria1 fibrillation. Her preoperative medical regimen consisted of digoxin, furosemide, verapamil, captopril, and coumadin. Preoperative laboratory studies were significant for a hemoglobin of 12.2 g/dL and hematocrit of 35.9%. In view of the relatively low hematocrit and the patient’s refusal to accept any blood products, the surgery was postponed and she was treated with oral iron and 10,000 units of r-erythropoietin by subcutaneous daily injection. She was rescheduled to undergo aortic valve replacement, mitral valve replacement, and tricuspid valvuloplasty 3 weeks later. At that time, the hemoglobin had risen to 14.7 g/dL, and the hematocrit to 42.6%. Coumadin had been discontinued 4 days prior to surgery. The PT was 13.6111.9 set, and the patient received 20 mg of vitamin K, intramuscularly (IM), on the day prior to surgery. The patient was premeditated with morphine, 5 mg, and scopolamine, 0.3 mg IM, and was transferred to the operating room while receiving O2 via nasal cannula. Her initial vital signs were a blood pressure (BP) 105/50 mmHg and heart rate (HR) of 85 beatsimin, in atria1 fibrillation. Peripheral venous, radial artery, and pulmonary artery (PA) catheters were placed. The patient’s baseline mean PA pressure (PAP) was 42 mmHg, central venous pressure (CVP) 23 mmHg, and cardiac output (CO) by thermodilution was 3.1 L/min. Following a smooth induction and maintenance of anesthesia with fentanyl, metocurine, and oxygen, her mean PAP was 16 mmHg. A transesophageal echocardiogram (TEE) probe was placed after induction. The patient was on total cardiopulmonary bypass (CPB) for 3 hours 52 minutes, during which time she underwent aortic and mitral valve replacements with St. Jude prostheses and DeVega tricuspid annuloplasty. Cardiotomy suction was used to return blood to the

Administering Cold Cardioplegia in Patients Undergoing Coronary Artery Bypass Grafting

In patients undergoing coronary artery bypass grafting (CABG), use of hypothermic cardioplegia for myocardial protection may not always achieve even cooling in the areas distal to a severely obstructed artery. Employing simultaneous myocardial temperature measurements, we documented warm areas in some patients having CABG. We then devised a technique of combined aortic root and intracoronary cardioplegic infusion. This has achieved prompt cooling of the warm areas and has resulted in uniform myocardial temperatures of 5 degrees to 8 degrees C.

EVALUATION OF ARTIFICIAL INTERFACES WITH IN VIVO SYSTEMS

There is universal agreement that the adverse reaction which occurs when blood comes in contact with foreign surfaces is the dominant cause of mortality and morbidity associated with prosthetic valve and vascular replacement or protracted mechanical cardiorespiratory support. Thus, during the past two decades major efforts have been made to discover inert, thromboresistant“biocompatib1e”-materials with durable and physiologically acceptable performance characteristics. Evaluation of potential cardiovascular implant materials in the intact animal remains a complex task, since our knowledge of factors associated with in vivo compatibility is so incomplete. The ideal study method would be performed in an environment that would accurately reproduce the clinical conditions demanded of the material, permit controlled perturbation of each of all known variables, and, finally, allow continuous analysis of biophysical and pathophysiologic events associated with or caused by the material. Presently, there is no testing method-in vitro, ex vivo or in vivo-that satisfies the criteria of the ideal study method. Discussion of the former two methods will be found elsewhere in this volume. It is the purpose of this communication to consider progress and problems with in vivo systems employed in evaluating artificial interfaces.

Experimental Large-Volume Hemodilution

1. Large-volume hemodilution was experimentally performed with a standardized reservoir arteriovenous fistula preparation in which intra- and extracorporeal volumes were kept constant. Vasopressors, buffers, hypothermia, and overinfusion were not employed.2. Control studies with 10 ml/kg of various diluents revealed hemodynamic, volumetric, and biochemical stability of the experimental preparation.3. Homologous blood exchange (100 ml/kg) with heart worm-free donors and recipients caused arterial hypotension, hepatic and pulmonary congestion, and depressed renal function.4. All diluents tested produced hypotension and metabolic acidosis under the conditions of the experiment when used in amounts approximately equivalent to canine blood volumes. Ten per cent of the diluted animals expired from shock.5. Blood pressure was initially better sustained with low molecular weight dextran, dextrose-Ringers-albumin, and dextrose-Ringers solutions, but the effect was short lived.6. Cardiac outputs and total blood volumes did not change appreciably during the exchange infusions. Hematocrit changes reflected maintenance of intravascular volume. Peripheral resistance fell significantly, shortly after the onset of constant volume exchange.7. Osmolality and oncotic activity of the diluents showed no clear-cut relationship to over-all stability of the infused animals.8. The clinical advantages of hemodilution have been well established. Hemodynamic, volumetric, and biochemical differences between clinical perfusions and the experiments outlined herein attest to the roles of over-infusion, buffering, and hypothermia in ameliorating the experimentally observed sequelae.9. The data suggest that the search should be continued for a more ideal blood substitute, as well as for low-prime, high-flow extra-corporeal systems.

Leland C. Clark and Frank Gollan: bubble oxygenators and perfusion hypothermia.

The 1940s and 1950s were witness to extraordinary innovativeness of many investigators, all seeking to develop satisfactory methods of hypothermia and extracorporeal circulation (ECC). That the genesis and ultimate fruition of an idea is virtually always the result of the efforts of many investigators is clearly reflected in the comprehensive texts of Galletti and Brecher [1], Shumacker [2], and Johnson [3] and brings to mind a remark attributed to the Nobel laureate, Lord Ernest Rutherford, that “it is not in the nature of things for any one man to make a sudden violent discovery. Science goes step by step, and every man depends on the work of his predecessors.” Having had the privilege of knowing for many years the distinguished physician investigator, Frank Gollan, as close friend and colleague, the time seemed appropriate to record a bit of history concerning events of a half-century ago in which he collaborated with Leland C. Clark, Jr, PhD, in the development of a gas dispersion oxygenator and, later, undertook extensive investigation of perfusion hypothermia. The oxygenator investigation began at the Fels Research Institute for the Study of Human Development at Antioch College where Dr Clark, the chairman of the Department of Biochemistry, Gollan, and a research associate, Vishwa Gupta, devised and described an efficient bubble oxygenator [4–6]. Although the apparatus was slightly modified later [7], there were three essential features: a multi-perforated disc, a coalescence (“defoaming”) chamber, and a combined bubble trap and oxygenated blood residence component (Figs. 1 and 2). Oxygen under pressure was dispersed through the porous disc into a venous blood column that instantly created arterialized foam. A key feature of the system was the capacity to efficiently coalesce the oxygenated foam by contact with glass beads that had been coated with DC Antifoam A, a methylpolysiloxane resin, which, only 2 years earlier, had been reported by the Dow Corning Laboratories to be both effective and innocuous [8]. The critical importance of DC Antifoam A in oxygenator performance was emphasized by Clark, Hooven, and Gollan: