Biomedical subjects

M T Swartz

Publications and source records attributed to M T Swartz.

At least 73 records · Page 4Linked to original sources

PubMedDate not supplied

Experience with an emergency resuscitation system.

The need for a portable extracorporeal support system that can be rapidly initiated for various types of cardiopulmonary failure is well known. The authors report on a system consisting of 3/8 inch tubing, a Sci-Med membrane oxygenator, Omnitherm heat exchanger, Biomedicus or Sarns centrifugal pump, portable battery, and oxygen tanks. The system is mounted on a cart for easy mobility and can be primed in 5-10 min. USCI, DLP, or Axiom cannulas can be inserted femorally. Over 30 months, 29 patients, aged 19-78 years, underwent extracorporeal membrane oxygenation (ECMO) support for cardiac arrest during catheterization (10 patients), shock secondary to acute myocardial infarction (MI) (10 patients), elective percutaneous transluminal coronary angioplasty (PTCA) support (four patients), postcardiotomy failure (four patients), and exposure hypothermia (one patient). Adequate support was achieved in all but one patient. Device flows ranged from 0.2 to 6.0 l/min. There were six survivors (elective PTCA support, three patients; cardiac arrest during catheterization, three patients). Complications included bleeding (15 patients), deep venous thrombosis (three patients), and pump failure (one patient). A portable ECMO system has been developed that allows rapid institution of circulatory support.

Angioplasty, Balloon, Coronary↗

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Thromboembolic complications with the Pierce-Donachy ventricular assist device.

Pierce-Donachy ventricular assist devices (VADs) were used to support 54 patients. None of the 27 patients supported less than 4 days had any visible thrombi in the VAD at explant. Of the 27 patients supported longer than 4 days, nine patients had visible thrombi. In this group of 27 patients, 19 received VAD support pending myocardial recovery, and anticoagulation consisted of dextran (4-15 days) and heparin during the weaning phase (1-2 days). The other eight patients had VADs implanted as bridges to cardiac transplantation. These patients also received dextran postoperatively (1-5 days), but were switched to a regimen of oral warfarin and dipyridamole. Duration of support for the nine patients in whom thrombi were found ranged from 4-27 days (mean, 12 days). The etiology of thrombus was probably related to mechanical problems in four patients, inadequate anticoagulation in two patients, sepsis in two patients, and unknown causes in one patient. Four of these patients suffered cerebral or peripheral injuries, which were probably embolic in two, and possibly embolic in two. One of these four patients survived, and two patients with thrombi but no emboli survived. One patient suffered a stroke, but no evidence of thrombi was found. Our incidence of thrombus with this VAD was 17%. Thrombi were related to inadequate anticoagulation, interrupted flow, or sepsis, but not to duration of support.

Female↗

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The incidence of isolated left ventricular failure in bridge-to-transplant candidates.

Twenty-one patients (pts) were supported with mechanical devices as a bridge to cardiac transplantation (Tx). Ventricular function was assessed by a combination of angiography, echocardiography, nuclear scans, hemodynamics, and visual inspection at the time of device insertion. Twelve pts had biventricular failure (BVF) and 11 received biventricular support with extracorporeal membrane oxygenation (two pts), biventricular assist devices (VAD) (eight pts), or an artificial heart (one pt). One BVF pt received a left VAD (LVAD) and drug support for severe right ventricular failure (RVF), which resolved after 48 hr. The remaining nine pts had left ventricular failure (LVF), with only mild to moderate RVF, and received LVADs with minimal drugs. Eleven pts were tx, with nine survivors. A comparison of pts with LVF vs BVF revealed no differences in age, gender, device flows, duration of support, diagnosis, number tx, or number survived. The incidence of LVF was 43% vs 57% BVF in bridge-to-transplant pts. LVAD support alone is often successful in pts with mild or moderate BVF, but is rarely successful in pts with severe BVF.

Adult↗

PubMedDate not supplied

Initial clinical experience with centrifugal pumps coated with the Carmeda process.

From September 5 to November 4, 1991, four consecutive patients placed on centrifugal ventricular assist devices (VADs) for cardiac failure were supported with Biomedicus pumps coated with the Carmeda bioactive surface. The study included three men and one woman aged 52-65 years. Two patients were supported with a right VAD, one with a left VAD, and one with a biventricular VAD. Support ranged from 35.5 to 65.75 hr, and VAD flows ranged from 1.0-5.5 L/min. Three patients were weaned from the VADs, and two survived. At explant, all four systems had clots adherent to the surface of the tubing and connectors on the pump outflow side of the circuit. Two patients had clots in the pump. Some of the clots were firmly adherent, whereas others dislodged easily after being rinsed with saline. All patients received heparin for insertion, and in three patients, heparin was reversed with protamine. Two patients received no further anticoagulation, and two received continuous heparin within 24 hr of implant to maintain activated clotting times of 140-150 sec. All patients had bleeding complications before and after VAD placement, necessitating multiple blood product transfusions. One patient who was weaned and survived had multiple thromboembolic strokes. These data suggest that clots can form on surfaces coated with the Carmeda process, even if a low dosage of heparin is used.

Aged↗

PubMedDate not supplied

The importance of patient mobility with ventricular assist device support.

Patients bridged to transplantation with ventricular assist devices (VADs) often require prolonged support. To reduce complications associated with bed rest, the authors developed a program to mobilize patients with VADs. Between August 1986 and May 1992, 25 men and 7 women aged 12-65 years (mean: 42.4 years) were bridged for possible transplantation. The 32 patients were supported with either a Novacor (n = 9) or a Thoratec (n = 23) VAD. Thirty-one patients were turned within 2-12 hr of VAD insertion and received range of motion therapy. Twenty-six patients sat in a chair 2-16 days (mean: 5 days) after VAD insertion. Twenty-one patients used a stationary bicycle, and 23 patients were ambulatory 3-57 days (mean: 11 days) after VAD insertion. Two patients were transplanted within 72 hr of device insertion. Twenty-one of the 23 ambulatory patients were successfully transplanted or weaned from the VAD and discharged from the hospital. Two ambulatory patients who were difficult to rehabilitate (ambulatory 22 and 57 days, respectively, after VAD insertion) died before transplantation. In conclusion, VAD patients should be mobilized early because the VAD can improve exercise capability and survival rate.

Adolescent↗

PubMedDate not supplied

Asymmetric intramyocardial lymphocytic accumulation during acute rejection in rat heart and heart-lung transplantation.

Lymphocytic accumulation in different areas of the myocardium during different phases of acute rejection were studied in rat heterotopic cardiac and cardiopulmonary allograft and isograft transplantation models. Indium 111-labeled syngeneic lymphocytes were injected 1 to 7 days after transplantation, and accumulation of the labeled cells in the graft was determined 24 hours later. The cardiac graft was divided into three segments: right ventricular (RV) free wall, epicardial portion of the left ventricle (LV) plus RV septum, and endocardial portion of the LV. In the subsequent heart-lung transplantation group, the LV epicardial portion plus RV septum segment was subdivided into LV epicardial portion and RV septum. Lymphocytic accumulation in each segment was compared between three groups according to the day the animal was killed after transplantation: days 2, 3 (group 1), days 4, 5 (group 2), and days 6, 7, 8 (group 3). Lymphocytic accumulation caused by rejection in group 1 and group 2 of both the cardiac and cardiopulmonary allografts showed significantly different intramyocardial distribution (p less than 0.01). Lymphocytic accumulation was consistently highest in RV free wall and lowest in LV endocardial portion. In group 3 specimens, lymphocytic accumulation was symmetrical in both the cardiac and cardiopulmonary allografts. In the cardiac allograft, the lymphocytic accumulation increased sharply on day 4 then declined to a nadir. This transient increase was not so pronounced in the cardiopulmonary allografts. The significantly decreased intramyocardial lymphocytic accumulation in group 2 of the cardiopulmonary allografts when compared with the cardiac allografts (p less than 0.01) is compatible with the clinical observation of a lower incidence of acute heart rejection in heart-lung transplant recipients. These data show an asymmetric accumulation of lymphocytes during acute heart rejection, which is due to increased lymphocytic affinity for the RV free wall.

Animals↗

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Status I heart transplant patients: conventional versus ventricular assist device support.

Since 1985, 59 United Network for Organ Sharing status I patients have been considered for heart transplantation. Thirty-four patients were supported with drugs and/or intraaortic balloon pump (IABP) (group I). Twenty-five patients were supported with ventricular assist devices (VADs, group II). Forty percent of the patients in each group died before transplantation. Of the 20 group I patients who underwent transplantation, all received inotropic drugs, and five also required IABPs. All 14 group II patients who underwent transplantation were bridged with VADs. No difference was found in age, sex, or cause of disease between the groups. Complications after transplantation were more common in group I. Fourteen group I patients (70%) and 14 group II patients (100%) were discharged from the hospital (p = 0.03). One year after transplantation, mean left ventricular ejection fraction by cardiac catheterization was 53% in group I (12 patients) and 72% in group II (11 patients; p = 0.0008). Although VAD support does not insure transplantation, it strongly favors transplantation survival in status I patients. These data further suggest an advantage of VAD support for long-term survival.

Actuarial Analysis↗

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Device related infections in patients supported with mechanical circulatory support devices for greater than 30 days.

Mechanical circulatory support with systems that require transcutaneous cannulas or drive lines are associated with a high incidence of device related infections. The development of infection often is related to the duration of support. Data were reviewed on 10 patients (nine men and one woman) supported with assist devices (Thoratec-five, Nova-cor-three, Sarns-one, Jarvik-one) for longer than 30 days (range, 31-440; mean, 137 days). Seven patients had device related infections. Five also had positive blood cultures with the same organisms responsible for the device related infection. Two had mediastinitis from an ascending infection (one cannula and one drive line). Eight patients were transplanted, with seven survivors. One patient was weaned and survived, and one died during support. These data show that device related infections are common and severe, but they do not preclude successful transplantation, weaning, or survival.

Anti-Bacterial Agents↗

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Importance of ventricular arrhythmias in bridge patients with ventricular assist devices.

To evaluate whether bridge to transplant patients with ventricular arrhythmias (VA; fibrillation or tachycardia) are at risk of death before or during ventricular assist device (VAD) support, the records of 28 patients who were supported with VADs for periods of 0.1 to 370 days (mean, 35.3 days) were retrospectively reviewed. VADs were effective in reducing the incidence of VA by 36%; however, patients with ischemic heart disease had a high incidence of VA (44%) during VAD. Only one patient with non-ischemic heart disease (8%) had VA during VAD. All five patients supported with left ventricular assist devices who had VA during support survived. Overall, the occurrence of VA during VAD was not a mortality risk. Since VAs are not predictors of survival, the presence of VA should not influence patient selection. While biventricular assist devices may be necessary in patients with the most severe VA, an LVAD provides excellent support in many patients.

Adolescent↗

PubMedDate not supplied

Importance of ventricular arrhythmias in recovery patients with ventricular assist devices.

The effect of ventricular arrhythmias (VA) on survival was retrospectively reviewed in 41 patients (33 men, 8 women) who were supported with Thoratec ventricular assist devices (VAD [Thoratec Medical Inc., Berkeley, CA]) (17 left, 9 right, and 15 biventricular). Ages ranged from 15 to 71 years (mean, 56 years), and duration of support was 0.1-17 days (mean, 4.7 days). There was no significant difference in age, gender, or type of support between survivors and nonsurvivors, and no correlation between the type of support and incidence of VA. Only two patients (both on left ventricular assist devices [LVAD]) died as a direct result of VA. There was no significant difference in the occurrence of VA before or during VAD support between survivors and nonsurvivors. These data show that evidence of VA is not a predictor of survival in patients in whom myocardial recovery is expected.

Adolescent↗

PubMedDate not supplied

Cost and reimbursement rates for investigational circulatory support.

The clinical evaluation of investigational circulatory support devices has, for the most part, been financed with private funds. St. Louis University initiated a system in 1986 to bill for investigational circulatory support devices and care related to their use. Charges for hospitalization and rates of reimbursement were reviewed in 32 patients who received Thoratec (Thoratec Laboratories Corp., Berkeley, CA [N = 26]), Novacor (Baxter Healthcare Corp., Oakland, CA [N = 4]), or Symbion (Symbion Inc., Tempe, AZ [N = 2]) total artificial heart devices. Duration of support ranged from 0.2 to 440 days (mean 32). Total charges ranged from $43,115 to $1,335,691 (mean $221,716). Charges for the devices and technical support relating directly to their use ranged from $10,305 to $96,030 (mean $28,246). The mean percentage of reimbursement (total charges/total paid) was 67%. Whereas it was uncertain in some patients whether or not the devices were paid for, commercial insurers are willing to reimburse at a high percentage for the total cost of care.

Costs and Cost Analysis↗

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Univentricular versus biventricular assist device support.

Controversy continues over whether patients should receive selective univentricular assist devices (UVADs) or biventricular assist devices (BVADs). Data from 39 patients supported for more than 2 days with Thoratec VADs were analyzed to compare mortality and morbidity between those receiving UVAD versus BVAD. Twenty-three patients received UVADs and 16 BVADs. Age, gender, and duration of support did not differ significantly between the two groups. Morbidity in VAD patients does not differ between UVAD and BVAD support. Survival is determined by the reversibility of pre-VAD myocardial damage or the eligibility for transplantation, rather than by the number of devices used. These data do not support the use of BVAD in all patients; they support a selective approach based on hemodynamic requirements.

Cardiac Surgical Procedures↗

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Bridge to heart transplantation: importance of patient selection.

Since 1986, 26 candidates were evaluated for mechanical support as a bridge to heart transplantation. Group 1 consisted of 15 patients who were accepted and who received support with a ventricular assist device (14 patients) or a total artificial heart (1 patient). Seven of the 15 patients received transplants and survived, whereas contraindications to transplant developed in seven patients while they were receiving support, and these seven died. One patient remains hospitalized after transplantation. Group 2 consisted of 11 patients rejected for circulatory support because of renal insufficiency or infection (9), pulmonary embolus (1), and cerebrovascular accident (1). Two group 2 patients underwent transplant procedures after their complications resolved, and one survived. One other group 2 patient who recovered without transplantation or mechanical support was discharged. There was no significant difference in age, gender, or cause of cardiogenic shock between the two groups. Four of five patients accepted for mechanical support on the first evaluation survived, and three of 10 accepted after the initial evaluation survived, indicating that delayed selection often results in complications that preclude transplantation and survival. Only one of the 26 patients survived without transplantation or support. These data emphasize the importance of patient selection on the outcome of bridging to transplantation.

Adult↗

PubMedDate not supplied

Left ventricular versus left atrial cannulation for the Thoratec ventricular assist device.

In a retrospective study of 28 patients (23 men, 5 women) supported with ventricular assist devices greater than 3 days, the effect of LV cannulation versus LA cannulation on device performance was compared. Patients ranged in age from 12 to 67 years (mean 46 years) and were supported for 3-81 days (mean 15 years). Fifteen patients were supported with left VADs (6 LV and 9 LA), and 13 patients were supported with BVADs (5 LV and 8 LA). The mode of operation 91% of the time was the fill-to-empty mode. Ten data points were taken for each patient. LV cannulation results in higher VAD flow index at decreased preload, lower VAD systolic and vacuum pressures, and shorter diastolic durations. Eleven of the 28 patients survived. Although survival was greater in patients with LV cannulation, survival was more dependent upon reversibility of myocardial damage, eligibility for transplantation, or the development of complications. These data indicate that LV cannulation provides better VAD performance than LA cannulation in the fill-to-empty mode.

Adolescent↗

PubMedDate not supplied

Oral anticoagulation in patients with ventricular assist devices.

Nine men aged 25-63 years (mean 42 years) received pulsatile ventricular assist devices (VADs) as a bridge to cardiac transplantation. Duration of support ranged from 8-266 days (mean 70.7 days); seven patients (pts.) were bridged with a LVAD and two received BVADs. All pts. were maintained on oral anticoagulants after initial intravenous (IV) heparin or dextran therapy. During warfarin therapy, supplemental IV heparin was used only if the prothrombin time fell below 1.5 times control (approximately 30% activity). In 639 days of support, there was one thromboembolic event due to mechanical failure, and one pt. had thrombus in the VAD which did not embolize.

Administration, Oral↗

PubMedDate not supplied

Retrospective analysis of the psychologic effects of mechanical circulatory support.

There is an increasing need to evaluate the psychologic impact of circulatory support because of the growing use of mechanical assist devices. Twenty-seven people, 12 survivors of mechanical circulatory assistance and 15 family members, were surveyed; nonsurvivors' families were not surveyed. The 12 survivors (ages 18 to 66 years; mean, 43 years) had been supported with Pierce-Donachy ventricular assist devices (nine patients) and the Novacor left ventricular assist system (one patient). One patient received a centrifugal pump, and one was supported with extracorporeal membrane oxygenation (ECMO). Duration of support ranged from 8 hours to 90 days (mean, 23 days). Ten people surveyed were spouses of these patients, and five were parents of children who had been supported with ECMO. Three patients were supported longer than 3 weeks, and four patients were awake and ambulatory during support. Financial worries were not a concern for 80% of the parents but were a concern for 80% of the spouses. Eighteen percent of the patients believed they were treated as an experiment, whereas 40% of their spouses thought they were. None of the parents thought their child was treated as an experiment. Sixty-seven percent of the patients stated that they have returned to a normal life-style, and 75% feel they have a brighter outlook on life. Six patients have returned to work, two are retired, two are disabled, and two have physical capabilities to work but choose not to. Eighty-nine percent of all those surveyed would recommend an assist device to someone who needed one. Although these procedures are often associated with severe medical and psychologic complications, 74% of the patients would agree to a second implant.

Adult↗

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Nursing care of a patient requiring prolonged mechanical circulatory support.

Four cardiac transplant candidates were supported with ventricular assist devices for periods ranging from 53 to 90 days (mean, 75 days). The patients were men who ranged in age from 36 to 49 years (mean, 44.5 years). Two patients had Pierce-Donachy biventricular assist devices (BVADs) and two patients had Novacor left ventricular assist systems (LVASs). Complications included infection (3 patients), development of antibodies (2 patients), bleeding (2 patients), and pump inflow obstruction (1 patient). All patients were maintained on an anticoagulation regimen which included warfarin and dipyridamole. They were extubated and ambulatory for most of the period of mechanical support. Thromboembolic complications did not develop in any of these patients, and they did not acquire infections which involved the mediastinum. They were successfully transplanted and discharged 11 to 25 days after transplantation. Although major complications were common in this small group of patients, all four patients achieved hemodynamic stability and became excellent candidates for cardiac transplantation. With proper patient selection and meticulous nursing care, current mechanical circulatory support technology is capable of maintaining patients consistently for periods of greater than 50 days.

Adult↗

PubMedDate not supplied

Bridging to heart transplantation with circulatory support devices.

Several devices are currently available for bridging to cardiac transplantation, but the efficacy of each has not been established. From September 1983 to March 1988 we supported 17 transplant candidates with mechanical assist devices. Extracorporeal membrane oxygenation (ECMO) was used to bridge two patients, external ventricular assist devices (VADs) were used in 11 patients, internal left ventricular assist systems (LVAS) were used in three patients, and implantable prosthetic replacement ventricles (TAH) were used in one patient. The 14 men and three women, aged 24 to 59 years (mean 46 years), suffered cardiogenic shock caused by ischemic (13 patients), postpartum (two patients), viral (one patient), and drug-induced (one patient) cardiomyopathy. Five patients with isolated left ventricular failure (LVF) received only left VADs, three patients with severe LVF and moderate right ventricular failure received LVAS, and nine patients with severe biventricular failure received ECMO (two patients), biventricular assist devices (six patients), and TAH (one patient). Patients were supported for periods of 1/2 to 90 days (mean 22) with flows of 2.15 to 3.39 L/min/m2. Ten patients underwent transplantation (eight of whom were discharged) and seven patients died without transplants. The two patients who received ECMO died 1 and 30 days after transplantation, in part as a result of ECMO complications. Seven patients were denied transplants because of renal failure (five patients), infection (five patients), bleeding (four patients), and cerebrovascular accident (two patients). The seven survivors were supported with VADs (five patients) or LVAS (two patients). Three had driveline infections, two had bleeding complications, two developed mediastinitis, and one each had hemolysis, cerebrovascular accident, and mechanical failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗