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Biomedical subjects

W P Dembitsky

Publications and source records attributed to W P Dembitsky.

At least 19 recordsLinked to original sources
PubMed1999

Bridging from acute to chronic devices.

Mechanical circulatory support used as a bridge to chronic transplantation is now a firmly established treatment modality. Trials evaluating circulatory assist for permanent circulatory assist device implications are underway. A population of patients is beginning to emerge who are resuscitated using readily available "acute" devices and need long-term supporting "chronic" device to bridge either cardiac transplantation or permanent device implantation. Careful management of this new acute-to-chronic bridge group will maximize the chances of a successful long-term outcome. The best strategies for management may only unfold by later analysis of larger populations. This article summarizes the current utilization of acute and chronic devices, as well as the small but growing population of acute-to-chronic bridge patients, and suggests what seem today to be sound management principles for them.

California↗
PubMed1999

The evolution and the current state of the art of pulmonary thromboendarterectomy.

Optimal reduction in pulmonary vascular resistance caused by chronic pulmonary embolism is obtained by bilateral pulmonary thromboendarterectomy with removal of occlusive material in all bronchopulmonary segmental arteries that are partially or completely obstructed. The most effective way to obtain this goal is the use of median sternotomy with cardiopulmonary bypass, deep hypothermia, and intermittent periods of circulatory arrest. During circulatory arrest, thromboendarterectomy is performed by specially designed dissectors that allow simultaneous dissection and removal of blood from the surgical field. The operative mortality rate for pulmonary thromboendarterectomy at the University of California, San Diego, between 1990 and 1998 was 9.2% in 1,049 patients.

Cardiopulmonary Bypass↗
PubMed1999

Postoperative management of the patient undergoing pulmonary thromboendarterectomy.

The postoperative course of the patient undergoing pulmonary thromboendarterectomy poses a unique series of challenges in terms of ventilatory care and hemodynamic management. Experience, cooperation, and interaction are necessary among the various disciplines providing care for these patients during the preoperative, operative, and postoperative phases of care. The purpose of this article is to share the approach necessary for the optimal postoperative care of the patient undergoing thromboendarterectomy, to present the theoretical justification for this care, and to delineate the areas of uncertainty that still exist.

Endarterectomy↗
PubMed1999

Comparison of functional capacity in patients with end-stage heart failure following implantation of a left ventricular assist device versus heart transplantation: results of the experience with left ventricular assist device with exercise trial.

BACKGROUND: Use of a permanent left ventricular assist device (LVAD) has been proposed as an alternate treatment of patients with end-stage heart failure. The purpose of this study was to compare the functional capacity of patients following implantation of a LVAD vs heart transplant (HTx). METHODS: Eighteen patients from 6 centers who received an intracorporeal LVAD as a bridge to HTx underwent treadmill testing 1 to 3 months post-LVAD and again post-HTx. Baseline and peak measurements, including oxygen consumption, blood pressures, and respiratory rate were made during each treadmill test. RESULTS: Peak oxygen consumption was 14.5+/-3.9 ml/kg/minute post-LVAD and 17.5+/-5.0 ml/kg/minute post-HTx (p < .005). The percentage of the predicted peak oxygen consumption based on gender, weight, and age was 39.5%+/-5.5% post-LVAD and 47.7%+/-10.9% post-HTx (p < .005). Exercise duration was lower post-LVAD than post-HTx (10.3+/-4.2 minute vs 12.5+/-5.4 minute, p < .05). After LVAD implantation, peak total oxygen consumption correlated with peak LVAD rate and output. Eight patients reached an LVAD rate of 120 beats per minute (bpm) before the conclusion of exercise, the maximum rate for the outpatient electric device. The peak respiratory exchange ratio post-LVAD was 1.15+/-0.22 and post-HTx was 1.15+/-0.18, consistent with a good effort in both groups. CONCLUSIONS: Patients demonstrated a lower functional capacity post-LVAD than post-HTx. For some patients functional capacity post-LVAD may be improved by a higher maximum LVAD rate and output.

Adult↗
PubMed1997

Effects of exercise during long-term support with a left ventricular assist device. Results of the experience with left ventricular assist device with exercise (EVADE) pilot trial.

BACKGROUND: Long-term implantation of a left ventricular assist device (LVAD) may be a future alternative treatment for end-stage heart failure. The objective of the present study was to determine the hemodynamic effects of supine bicycle exercise and functional capacity during upright treadmill exercise in 10 patients after LVAD implantation placed for refractory heart failure as a bridge to cardiac transplantation. METHODS AND RESULTS: With supine bicycle exercise, 46 +/- 25 days after device placement, heart and LVAD rates increased in parallel from 87 +/- 12 to 117 +/- 14 bpm and 82 +/- 18 to 107 +/- 21 bpm, respectively. Peak O2 consumption was 8.2 +/- 1.7 mL O2.kg-1.min-1. Fick Systemic blood flow rose from 5.0 +/- 1.2 to 7.8 +/- 2.5 L/min. Right atrial and pulmonary capillary wedge pressures increased from 6 +/- 4 and 5 +/- 3 mm Hg to 12 +/- 5 and 13 +/- 8 mm Hg, respectively. End-diastolic left ventricular dimension increased from 3.9 +/- 1.3 to 4.8 +/- 1.6 cm; however, right ventricular dimension decreased from 3.2 +/- 1.0 to 2.3 +/- 0.9 cm. With upright treadmill exercise, peak O2 consumption was 14.1 +/- 2.9 mL O2.kg-1.min-1. CONCLUSIONS: This study indicates that exercise during long-term LVAD support is safe and is not limited by right heart decompensation. It also justifies a larger study to examine how exercise after LVAD implantation compares with that after cardiac transplantation.

Adult↗
PubMed1997

The treatment of low cardiac output syndrome following cardiopulmonary bypass using delayed sternal closure.

The purpose of this study, was to ascertain whether delayed sternal closure (DSC) could eliminate the need for an intra-aortic balloon pump (IABP) or ventricular assist device (VAD) in patients with low cardiac output syndrome (LCOS) following coronary artery bypass grafting surgery (CABG). To investigate this, the records of 3014 patients undergoing CABG were retrospectively reviewed. Sixty (2.0%) patients had a relative or absolute contraindication to IABP or VAD use and required DSC for LCOS. DSC resolved 45 (75%) of these patients' LCOS, requiring an average of 1.6 +/- 0.7 days and producing a mean change in cardiac index of +1.0 +/- 0.3 L/min/m2. Fifteen (25%) of these patients did not resolve their LCOS after DSC and required either an IABP (11) or a VAD (4). Significant postoperative morbidity occurred in 22 (36.7%) patients but were not related to DSC. Only one (1.7%) sternal wound infection occurred from a total of 147 patient-days of DSC. Operative mortality was 47 per cent (28) but was not unexpected based on the number of urgent/emergent (48; 80%) and reoperative (40; 67%) procedures but does not appear to be related to the technique of DSC. DSC appears to be a simple and safe method for treating LCOS following CABG. It is effective in resolving the majority of patients' LCOS without the addition of any significant morbidity. DSC also spares these patients the added morbidity, mortality, and cost associated with circulatory assist devices.

Adult↗
PubMed1996

Comparisons of methods of myocardial hypothermia for cardiac transplantation.

BACKGROUND: Myocardial hypothermia of less than 10 degrees C is an essential component of preservation of donor hearts before implantation. Here we report temperature changes and comparison of methods for maintenance of myocardial hypothermia during implantation. METHODS: Twenty patients were prospectively randomized into two equal groups. In one cohort myocardial hypothermia was maintained by the "Stanford method" of continuous lavage of the pericardium and left atrium with refrigerated saline solution. In the other a cooling jacket was used without saline lavage. Temperatures at multiple sites were measured at 30-second intervals from initiation of cardiac suturing until aortic cross-clamp removal. Comparisons were made between groups at each temperature site. RESULTS: The cooling jacket group temperatures were significantly lower at the left ventricular epicardium and endocardium than those of the Stanford method group. CONCLUSIONS: During cardiac implantation maintenance of myocardial hypothermia with a cooling jacket resulted in significantly deeper and more consistent hypothermia of the left ventricle than pericardial and left atrial lavage with refrigerated saline solution. Blood loss from aspirated saline lavage and perfusate dilution by the saline solution were eliminated.

Adult↗
PubMed1996

Cost reduction by combined carotid endarterectomy and coronary artery bypass grafting.

A significant cost reduction is likely if patients who require coronary artery bypass grafting with significant carotid stenosis have simultaneous carotid endarterectomy and bypass grafting, provided risk is not increased. To investigate this issue, we retrospectively identified cases from February 1977 to May 1994 with first-time isolated carotid endarterectomy, coronary bypass, or combined procedures. In the isolated carotid endarterectomy population, median age was 69 years and 58% (85/146) were male, as compared with 68 years and 68% (68/100) male in the combined group; median age of the coronary bypass cohort was 65 years and 76% (381/500) male. A significantly higher percentage of patients in the coronary bypass versus combined group were in New York Heart Association functional class IV. In the combined group there was a significantly higher incidence of older age, diabetes, hypertension, hyperlipidemia, renal failure, and congestive heart failure. There was no difference among the three groups with respect to hospital mortality (0%, 3.4%, and 4.0%, respectively) and permanent stroke (0.7%, 1.2%, and 0%, respectively). Hospital costs were $4,896, $10,959 and $11,089, respectively, with a savings of $4,766 (30%), and Medicare hospital reimbursement was $8,575, $23,071, and $23,071, respectively, with a savings of $10,077 (25.3%). Thus, in appropriate patients, a combined procedure is cost effective, eliminating a second surgical procedure and the cost of the postoperative stay (3.7 +/- 2.4 days) associated with isolated carotid endarterectomy. Risk of permanent stroke or death is not increased.

Aged↗
PubMed1995

Anterograde perfusion in acute limb ischemia secondary to vascular occlusive cardiopulmonary support.

Cardiopulmonary support (CPS) can resuscitate a patient with circulatory collapse during high-risk interventional procedures, although vascular complications may accompany its use. We report a patient with cardiogenic shock secondary to myocardial infarction who required extended CPS support associated with acute infarct-related coronary artery angioplasty and stent placement. Leg ischemia due to an occlusive cannula was resolved using a percutaneous anterograde perfusion device. In general, such devices may have application in patients dependent on mechanical support associated with limb ischemia.

Acute Disease↗
PubMed1995

New technique for lesser saphenous vein harvesting.

A new technique using the Thompson self-retaining retractor system (Thompson Surgical Instruments, Inc, Traverse City, MI) to harvest lesser saphenous veins is presented. This modification, used in 10 patients undergoing redo myocardial revascularization, provided a rapid, comfortable, and convenient method for harvesting lesser saphenous veins.

Coronary Artery Bypass↗
PubMed1994

Venovenous extracorporeal life support in traumatic bronchial disruption and adult respiratory distress syndrome using surface-heparinized equipment: case report.

Venovenous extracorporeal membrane oxygenation and carbon dioxide removal was utilized to support a patient with traumatic bronchial disruption and associated injuries. With use of surface-heparinized perfusion equipment, low levels of anticoagulation were maintained allowing surgical repair of the bronchial injury and recovery from acute respiratory failure without significant hemorrhage.

Adolescent↗
PubMed1994

Effect of prophylactic epsilon-aminocaproic acid on blood loss and transfusion requirements in patients undergoing first-time coronary artery bypass grafting. A randomized, prospective, double-blind study.

The prophylactic use of aprotinin has recently been reported to be associated with a significant decrease in blood loss in patients undergoing cardiopulmonary bypass procedures. One of the primary effects of aprotinin is prevention of plasmin degradation of platelet function. Because aprotinin is commercially unavailable in the United States at this time, we evaluated epsilon-aminocaproic acid with respect to decreased perioperative blood loss. We prospectively randomized 40 patients undergoing first-time coronary artery bypass grafting without prior sternotomy into two groups: one group (n = 21) received prophylactic and preincision epsilon-aminocaproic acid and the other (n = 19) received a placebo. No significant differences existed between patient groups with respect to age, body surface area, cardiopulmonary bypass time, and aortic crossclamp time. Cumulative blood loss at 4, 8, 12, and 24 hours after chest closure was significantly less in the epsilon-aminocaproic acid group (426 +/- 242 ml versus 634 +/- 224 ml, p = 0.002, at 12 hours). Only one patient receiving epsilon-aminocaproic acid was given blood or blood components compared to five patients in the placebo group (p < 0.02). D-dimers and fibrin split products were significantly less prevalent in the epsilon-aminocaproic acid group (at 4 hours: 0/20 versus 7/16, p < 0.002 and 5/20 versus 12/19, p < 0.05, respectively). None of the patients had a perioperative myocardial infarction or cerebrovascular accident. The prophylactic administration of epsilon-aminocaproic acid results in a significant decrease in blood loss in patients undergoing first-time coronary artery bypass grafting, and blood transfusion requirements are significantly less. It may be important to administer epsilon-aminocaproic acid before skin incision to be optimally effective.

Aged↗
PubMed1993

Exercise hemodynamics during long-term implantation of a left ventricular assist device in patients awaiting heart transplantation.

OBJECTIVES: The goal of this study was to assess patients with end-stage heart disease after implantation of a left ventricular assist device at rest and during exercise compatible with activities of daily life. BACKGROUND: Mechanical circulatory assistance with a left ventricular assist device is an accepted therapy for bridging patients with end-stage heart disease to heart transplantation and has been proposed for long-term implantation. METHODS: Three patients (aged 37, 42 and 57 years) with end-stage heart failure required implantation of a pneumatically driven, asynchronous Thermedics left ventricular assist device while awaiting heart transplantation. All were assessed 1 month later during graded supine bicycle exercise (maximal work load 100 to 150 W). Detailed central hemodynamics, including continuous pulmonary artery oxygen saturation and oxygen consumption measurements, were obtained. Two of the patients also underwent upright treadmill exercise with oxygen consumption measurements. RESULTS: During supine bicycle exercise, the heart rate increased from 93 +/- 37 beats/min (95% confidence interval: mean +/- t0.025 x SE) at rest to 119 +/- 54 beats/min and left ventricular assist device rate increased from 82 +/- 47 to 109 +/- 55 beats/min. Oxygen consumption increased from 3.0 +/- 0.9 to 8.7 +/- 2.9 ml oxygen/min per kg body weight. Cardiac output increased from 6.0 +/- 4.4 to 9.6 +/- 7.1 liters/min, yielding an average exercise factor of 8.5 +/- 7.7 and an exercise index of 0.83 +/- 0.61. The patients assessed during treadmill exercise achieved a maximal oxygen consumption of 14.3 and 16.7 ml of oxygen/min per kg. No thromboembolic or other complications attributable to left ventricular assist device implantation occurred during the duration of support. All patients survived orthotopic heart transplantation and are doing well. CONCLUSIONS: Significant work loads compatible with activities of daily life and adequate exercise hemodynamics were demonstrated by these patients while awaiting heart transplantation. Definitive conclusions regarding the use of this device must be viewed as preliminary because only three patients were involved in this study and the failure rate may be as high as 71% (95% confidence interval of left ventricular assist device success as a bridge to transplantation 29.3% to 100%). Final conclusions regarding the safety and efficacy of the left ventricular assist device as a possible long-term circulatory support device must await results of larger multicenter trials in progress.

Adult↗
PubMed1993

Emergency resuscitation using portable extracorporeal membrane oxygenation.

Manual cardiopulmonary resuscitation is currently the standard treatment for cardiac arrest patients both in and out of the hospital. Accumulated experimental and anecdotal clinical evidence suggests enhanced survival in patients with extreme circulatory decompensation who have been emergently supported with portable cardiopulmonary bypass. Long-term survival is possible even when application is delayed, but early institution of support after cardiac arrest in selected patients offers the best survival advantages. In our hospital this has been achieved by training a team of in-house personnel to emergently prepare, apply, and temporarily manage cardiopulmonary bypass until personnel with greater specialty training arrive. Machinery needed to perform emergency cardiopulmonary bypass is currently available in all hospitals with open heart surgery programs. Simple support is often therapeutic but can also serve as a bridge to definitive diagnostic and other therapeutic procedures. Commercial units are becoming more biocompatible and easier to use, making both wider application and more prolonged support likely in the future.

Cardiopulmonary Resuscitation↗
PubMed1992

Prolonged extracorporeal circulation for acute myocarditis.

Total circulatory support for acute reversible myocardial failure is rarely used in clinical situations outside the postoperative period following cardiac surgery. We treated an 8-year-old girl who suffered acute viral myocarditis and sustained cardiac arrest requiring cardiopulmonary bypass for resuscitation. This was accomplished with the use of the portable cardiopulmonary support system (CPS), which consists of a centrifugal pump and a membrane oxygenator. This patient was placed on CPS in Hawaii and transported after 3 days to San Diego (4200 km) for further mechanical support and possible heart transplantation. Adequate cardiac function returned and CPS was stopped after 6 days. She is alive and well, attending school two and a half years after the event. Prolonged use of CPS for acute myocardial failure outside the operating room, including long distance transportation, is effective and easily accomplished with currently and widely available equipment, and should be used in acute, reversible catastrophic heart disease.

Acute Disease↗