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Biomedical subjects

M C Oz

Publications and source records attributed to M C Oz.

At least 73 records · Page 4Linked to original sources
PubMed1999

Vasopressin deficiency and pressor hypersensitivity in hemodynamically unstable organ donors.

BACKGROUND: Solid organ donors often develop hypotension due to vasodilation, and recently we observed that a variety of vasodilatory states are characterized by vasopressin deficiency and hypersensitivity. Thus, we investigated the prevalence of vasopressin deficiency in hypotensive solid organ donors without clinical evidence of diabetes insipidus; we also investigated the vasopressor effect of vasopressin replacement in hypotensive donors. METHODS AND RESULTS: Fifty organ donors were evaluated for hemodynamic instability, (mean arterial pressure [MAP]</= 70 mm Hg despite the use of catecholamine vasopressors), and in those unstable donors who were not already receiving exogenous vasopressin, low-dose vasopressin was administered as a continuous infusion (0. 04 to 0.1 U/min). MAP, catecholamine requirements, serum vasopressin, and serum osmolality were obtained before and after vasopressin administration. Ten patients meeting the enrollment criteria received vasopressin and MAP increased from 72.2+/-3.5 to 89.8+/-4.2 mm Hg, (P<0.05), allowing for complete discontinuation of catecholamine pressors in 4 (40%) patients and a decrement in pressor dose in 4 (40%). Plasma vasopressin levels (2.9+/-0.8 pg/mL) were low for the degree of hypotension. CONCLUSIONS: Hemodynamically unstable organ donors without clinically apparent diabetes insipidus display a defect in the baroreflex-mediated secretion of vasopressin. In these patients, low-dose vasopressin significantly increases blood pressure with a pressor response sufficient to reduce catecholamine administration.

Adolescent↗
PubMed1999

Activation-induced T-cell death and immune dysfunction after implantation of left-ventricular assist device.

BACKGROUND: Cardiac transplantation is a limited option for end-stage heart failure because of the shortage of donor organs. Left-ventricular assist devices (LVADs) are currently under investigation as permanent therapy for end-stage heart failure, but long-term successful device implantation is limited because of a high rate of serious infections. To examine the relation between LVAD-related infection and host immunity, we investigated immune responses in LVAD recipients. METHODS: We compared the rate of candidal infection in 78 patients with New York Heart Association class IV heart failure who received either an LVAD (n=40) or medical management (controls, n=38). Fluorochrome-labelled monoclonal antibodies were used in analyses of T-cell phenotype. Analysis of T-cell function included intradermal responses to recall antigens and proliferative responses after stimulation by phytohaemagglutinin, monoclonal antibodies to CD3, and mixed lymphocyte culture. We measured T-cell apoptosis in vivo by annexin V binding, and confirmed the result by assessment of DNA fragmentation. Activation-induced T-cell death was measured after T-cell stimulation with antibodies to CD3. All immunological tests were done at least 1 month after LVAD implantation. Between-group comparisons were by Kaplan-Meier actuarial analysis and Student's t test. FINDINGS: By 3 months after implantation of LVAD, the risk of developing candidal infection was 28% in LVAD recipients, compared with 3% in controls (p=0.003). LVAD recipients had cutaneous anergy to recall antigens and lower (<70%) T-cell proliferative responses than controls after activation via the T-cell receptor complex (p<0.001). T cells from LVAD recipients had higher surface expression of CD95 (Fas) (p<0.001) and a higher rate of spontaneous apoptosis (p<0.001) than controls. Moreover, after stimulation with antibodies to CD3, CD4 T-cell death increased by 3.2-fold in LVAD recipients compared with only 1.2-fold in controls (p<0.05). INTERPRETATION: LVAD implantation results in an aberrant state of T-cell activation, heightened susceptibility of CD4 T cells to activation-induced cell death, progressive defects in cellular immunity, and increased risk of opportunistic infection.

Adolescent↗
PubMed1999

100 long-term implantable left ventricular assist devices: the Columbia Presbyterian interim experience.

BACKGROUND: The use of left ventricular assist devices (LVADs) as bridge to transplantation is now accepted as a standard of care for a subset of end-stage heart failure patients. Our interim experience with both pneumatically and electrically powered ThermoCardiosystems LVADs is presented to outline the benefits and limitations of device support as well as discuss its potential role as bridge to recovery and as destination therapy. METHODS AND RESULTS: Detailed records were kept prospectively for all patients undergoing LVAD insertion. One hundred LVADs were inserted over 7 years into 95 patients, with an overall survival rate of 75% and a transplantation rate of 70%. Four patients underwent device explant for recovered myocardial function. Three patients received LVADs as destination therapy in the ongoing REMATCH (Randomized Evaluation of Mechanical Assist Treatment for Congestive Heart failure) trial. Overall mean patient age was 51 years, and mean duration of support was 108 days. There were 25 device-related infections including the drive line, device pocket, and blood-contacting surfaces. Cerebral vascular accidents and other embolic events occurred in 7 patients with six deaths. There were four device malfunctions and nine graft-related hemorrhages, resulting in six reoperations and three deaths. CONCLUSIONS: The use of long-term implantable LVADs will likely not be limited to bridge to transplantation. The REMATCH trial has commenced to study the role LVADs may have as an alternative to medical management. Furthermore, as the issues of myocardial recovery are examined, the "bridge to recovery" may be an important additional role for these assist devices.

Cause of Death↗
PubMed1999

Reduction of retrosternal and pericardial adhesions with rapidly resorbable polymer films.

BACKGROUND: The formation of postoperative cardiac adhesions makes a repeat sternotomy time consuming and dangerous. Many attempts have been made to solve this problem by using either drugs to inhibit fibrinolytic activity or different types of pericardial substitutes. The results have not been satisfactory. METHODS: The efficacy of bioresorbable film prototypes made of polyethylene glycol (EO) and polylactic acid (LA) (EO/LA = 1.5, 2.5, and 3.0) in the prevention of adhesions after cardiac operations in canine models was tested. After desiccation and abrasion of the epicardium, a transparent bioresorbable film was placed over the heart. The pericardium was closed to allow intrapericardial adhesions (n = 32) or left open and attached to the chest wall to induce retrosternal adhesions (n = 17). Postoperative recovery was similar among the groups. Retrosternal and pericardial adhesions were evaluated at necropsy 3 weeks later by assessing area, tenacity, and density of the adhesions. RESULTS: In the control dogs, tenacious, dense adhesions were observed. In contrast, adhesion formation was reduced at all sites covered by the films. The bioresorbable films were efficacious in the reduction of adhesion formation between epicardium and pericardium or between epicardium and sternum after cardiac operation. The EO/LA 1.5 film most effectively prevented the early adhesions. CONCLUSIONS: The bioresorbable films (EO/LA = 1.5, 2.5, and 3.0) significantly reduced adhesion formation, with EO/LA = 1.5 (Repel CV) being optimal. As the barrier was rapidly resorbed, the capsule formation induced by permanent barriers was avoided.

Absorption↗
PubMed1999

Left ventricular assist device bridge-to-transplant network improves survival after failed cardiotomy.

BACKGROUND: Postcardiotomy cardiogenic shock has been reported to occur following 2% to 6% of cardiac surgical procedures. Both the mandatory New York state cardiac surgery database and a voluntary ventricular assist device registry have reported hospital discharge rates of only 25% in postcardiotomy patients supported with ventricular assist devices. Although many centers have access to short-term mechanical cardiac assist devices, most lack a dedicated team which can resuscitate these critically ill patients. Equally important, these centers do not have easy access to effective cardiac replacement options, including implantable left ventricular assist devices (LVADs) and heart transplantation. METHODS: A referral network based upon the use of implantable LVADs as a bridge to transplantation in patients with postcardiotomy heart failure was established in the New York City region. Cardiac surgery centers were encouraged to contact our center early following any failed cardiotomy. RESULTS: Forty-four patients entered our postcardiotomy network: 12 recovered without an implantable LVAD, 23 received implantable LVADs, and six expired without long-term LVAD support. Of the 44 referrals, 29 (66%) survived to hospital discharge. Of the 23 patients receiving implantable LVADs, two recovered myocardial function and underwent LVAD explant, 14 were bridged to heart transplant, one underwent an emergent heart transplant, and six expired. Of the 23 implantable LVAD patients, 17 (74%) survived to hospital discharge. CONCLUSIONS: Regional networks centered around bridge-to-transplant facilities that have an aggressive approach to implantable LVAD placement may substantially improve the survival rate of patients with postcardiotomy heart failure.

Adult↗
PubMed1999

Superior protection in orthotopic rat lung transplantation with cyclic adenosine monophosphate and nitroglycerin-containing preservation solution.

BACKGROUND: Primary lung graft failure is common, and current lung preservation strategies are suboptimal. Because the decline in lung levels of cyclic adenosine monophosphate and cyclic guanosine monophosphate during preservation could enhance adhesiveness of endothelial cells for leukocytes as well as increase vascular permeability and vasoconstriction, we hypothesized that buttressing these levels by means of a preservation solution would significantly improve lung preservation. METHODS: An orthotopic rat left lung transplantation model was used. Lungs were harvested from male Lewis rats and preserved for 6 hours at 4 degrees C with (1) Euro-Collins solution (n = 8); (2) University of Wisconsin solution (n = 8); (3) low-potassium dextran glucose solution (n = 8); (4) Columbia University solution (n = 8), which contains a cyclic adenosine monophosphate analog (dibutyryl cyclic adenosine monophosphate) and a nitric oxide donor (nitroglycerin) to buttress cyclic guanosine monophosphate levels; or (5) Columbia University solution without cyclic adenosine monophosphate or nitroglycerin (n = 8). PaO2, pulmonary vascular resistance, and recipient survival were evaluated 30 minutes after left lung transplantation and removal of the nontransplanted right lung from the pulmonary circulation. RESULTS: Among all groups studied, grafts stored with Columbia University solution demonstrated the highest Pa O2 (355 +/- 25 mm Hg for Columbia University solution versus 95 +/- 22 mm Hg for Euro-Collins solution, P <.01, 172 +/- 55 mm Hg for University of Wisconsin solution, P <.05, 76 +/- 15 mm Hg for low-potassium dextran glucose solution, P <.01, and 82 +/- 25 mm Hg for Columbia University solution without cyclic adenosine monophosphate or nitroglycerin, P <.01) and the lowest pulmonary vascular resistances (1 +/- 0.2 mm Hg * mL-1 * min-1 for Columbia University solution versus 12 +/- 4 mm Hg * mL-1 * min-1 for Euro-Collins solution, P <.01, 9 +/- 2 mm Hg * mL-1 * min-1 for University of Wisconsin solution, 14 +/- 6 mm Hg * mL-1 * min-1 for low-potassium dextran glucose solution, P <.01, and 8 +/- 2 mm Hg * mL-1 * min-1 for Columbia University solution without cyclic adenosine monophosphate and nitroglycerin). These functional and hemodynamic improvements provided by Columbia University solution were accompanied by decreased graft leukostasis and decreased recipient tumor necrosis factor alpha and interleukin 1alpha levels compared with the other groups. In toto, these improvements translated into superior survival among recipients of Columbia University solution-preserved grafts (100% for Columbia University solution, 37% for Euro-Collins solution, P <.01, 50% for University of Wisconsin solution, P <.05, 50% for low-potassium dextran glucose solution, P <.05, and 13% for Columbia University solution without cyclic adenosine monophosphate and nitroglycerin, P <.01). CONCLUSION: Nitroglycerin and cyclic adenosine monophosphate confer beneficial vascular effects that make Columbia University solution a superior lung preservation solution in a stringent rat lung transplantation model.

Adenosine↗
PubMed1999

Time-dependent cellular population of textured-surface left ventricular assist devices contributes to the development of a biphasic systemic procoagulant response.

OBJECTIVE: Textured-surface left ventricular assist devices (LVAD) have been shown to enhance ventricular function and survival in patients with end-stage heart failure. Furthermore, we have described a procoagulant physiology in our LVAD population with sustained thrombin generation (elevated thrombin-antithrombin III complex and prothrombin fragment 1+2) and fibrinolysis (D-dimers), even up to 335 days after LVAD placement. To explain such sustained activation of coagulation, we speculated that the LVAD surface selectively adsorbed and promoted activation of circulating blood cells. METHODS: In a prospective study of 20 patients with LVADs, we examined samples of peripheral blood as well as cells harvested from the surface of the LVADs at the time of their explantation for procoagulant proinflammatory markers. RESULTS: Analysis of the cells populating the LVAD surface revealed the presence of pluripotent hematopoietic CD34(+) cells, as well as cells bearing monocyte (CD14)/macrophage (CD68) markers, which also expressed procoagulant tissue factor. Reverse transcriptase-polymerase chain reaction confirmed cellular activation on the LVAD surface, revealing transcripts for interleukin 1alpha, interleukin 2, and tumor necrosis factor alpha, in addition to vascular cell adhesion molecule-1 consistent with their capacity to continually recruit and activate circulating cells, thereby propagating their response. In the periphery, elevated levels of tissue factor were found in the plasma of patients with LVADs, along with enhanced procoagulant activity. CONCLUSION: These observations suggest that the LVAD surface selectively absorbs and activates circulating hematopoietic precursor and monocytic cells, thereby creating a sustained prothrombotic and potentially proinflammatory systemic environment.

Adolescent↗
PubMed1999

Long-term survival after cardiac retransplantation: a twenty-year single-center experience.

OBJECTIVE: To identify risk factors for survival after cardiac retransplantation and compare the survival after retransplantation with that after primary cardiac transplantation. METHODS: A retrospective analysis of 952 patients undergoing cardiac transplantation for the treatment of end-stage heart disease at a single center between 1977 and October 1997. Of these, 43 patients (4.5%) underwent cardiac retransplantation for cardiac failure resulting from transplant-related coronary artery disease, rejection, and early graft failure. RESULTS: No significant difference in actuarial patient survival was found by Kaplan-Meier analysis at 1, 2, and 5 years between patients undergoing primary transplantation and those undergoing retransplantation 76%, 71%, and 60% versus 66%, 66%, and 51%, respectively (P =.2). Multivariable analysis identified a shorter interval between transplants and an initial diagnosis of ischemic cardiomyopathy as significant risk factors for death after retransplantation (P =.04 and.03, respectively). Since 1993, when our criteria for patient selection for retransplantation were revised on the basis of earlier experience to exclude patients with allograft dysfunction as a result of primary graft failure and those with intractable acute rejection occurring less than 6 months after transplantation, the survival has been significantly better (<1993 = 45%, 45%, and 33% versus >/=1993 = 94%, 94%, and 94% at 1, 2, and 4 years, respectively, P =.003). CONCLUSION: The long-term outcome of cardiac retransplantation is comparable with that of primary transplantation, especially in patients with transplant-related coronary artery disease. Patient characteristics and other preoperative variables should assist in the rational application of retransplantation to ensure optimal use of donor organs.

Actuarial Analysis↗
PubMed1999

Improved survival rates support left ventricular assist device implantation early after myocardial infarction.

OBJECTIVES: Implantation of left ventricular assist devices (LVADs) early after acute myocardial infarction (MI) has traditionally been thought to be associated with high mortality rates due to technical limitations and severe end-organ dysfunction. At some experienced centers, doctors have refrained from earlier operation after MI to allow for a period of hemodynamic and end-organ stabilization. METHODS: We retrospectively investigated the effect of preoperative MI on the survival rates of 25 patients who received a Thermocardiosystems Incorporated LVAD either <2 weeks (Early) (n = 15) or >2 weeks (Late) (n = 10) after MI. Outcome variables included perioperative right ventricular assistance (and right-sided circulatory failure), hemodynamic indexes, percent transplanted or explanted, and mortality. RESULTS: No statistically significant differences were demonstrated between demographic, perioperative or hemodynamic variables between the Early and Late groups. Patients in the Early group demonstrated a lower rate of perioperative mechanical right ventricular assistance, but had a higher rate of perioperative inhaled nitric oxide use. In addition, 67% of patients in the Early group survived to transplantation and 7% to explantation, findings comparable to those in the Late group (60% and 0% respectively). CONCLUSIONS: This clinical experience suggests that patients may have comparable outcomes whether implanted early or late after acute MI. These data therefore support the early identification and timely application of this modality in post-MI LVAD candidates, as this strategy may also reveal a subgroup of patients for whom post-MI temporary LVAD insertion may allow for full ventricular recovery.

Adult↗
PubMed1999

Retinoic acid suppresses intimal hyperplasia and prevents vessel remodeling following arterial injury.

Vitamin A and its derivatives (retinoids) are capable of inhibiting vascular smooth muscle cell proliferation in vitro. The present study examines the effect of two retinoids, all-trans retinoic acid and 13-cis retinoic acid, on intimal hyperplasia following arterial injury. After receiving varying doses of all-trans retinoic acid or 13-cis retinoic acid, 78 male Sprague-Dawley rats underwent standard balloon catheter denudation of the left common carotid artery. Morphometric analysis and immunohistochemistry for proliferating cell nuclear antigen was performed at early and late time points. Intimal/medial ratios were reduced in a dose-dependent fashion for animals treated with all-trans retinoic acid (P = 0.001) and 13-cis retinoic acid (P = 0.004). Proliferating cell nuclear antigen labeling indices were reduced after treatment with all-trans retinoic acid and 13-cis retinoic acid at early time points post-injury. At a dose of 10 mg/kg, both all-trans retinoic acid and 13-cis retinoic acid inhibited vessel remodeling as measured by increases in luminal diameter (P < 0.05) and external elastic lamina (P < 0.05). Retinoids are an attractive clinical option for the treatment of restenosis following angioplasty and arterial surgery.

Animals↗
PubMed1999

Membrane stabilization in harvested vein graft storage: effects on adhesion molecule expression and nitric oxide synthesis.

OBJECTIVE: Expression of cellular adhesion molecules in human saphenous vein grafts may occur even during harvesting and storage, before the grafts have been implanted as bypass conduits. This may play a role in graft adaptation to arterial flow conditions, which may play an important role in late graft patency. In this study, ketotifen, a mast cell membrane stabilizing agent was studied for its effects on reducing endothelial reactivity during storage of harvested vein graft segments. METHODS: Human saphenous vein grafts, obtained from seven patients and then divided into two equal parts of control and study specimens, were stored in either heparinized blood (Group A) or heparinized blood containing 100 microg/ml ketotifen (Group B) for 1 h at room temperature. Specimens were analyzed by Western blotting to quantify ICAM-1, E-selectin, P-selectin, VCAM-1, and inducible nitric oxide synthase (NOS-2) expression, as well as tissue cGMP levels in response to topical application of an endothelium-independent vasodilator. RESULTS: ICAM-1, E-selectin and P-selectin expression did not differ between the groups. However, VCAM-1 expression was significantly lower in Group B (460 +/- 29 vs. 289 +/- 50, P = 0.01). NOS-2 expression (488 +/- 64 vs. 577 +/- 38, P = 0.02) and tissue cGMP levels (2.2 +/- 0.6 pmol/ml vs. 5.7 +/- 1.7 pmol/ml, P = 0.01) in response to nitroglycerin (24 +/- 10% vs. 11 +/- 5%, P = 0.02) were higher in Group B. CONCLUSIONS: Of all of the adhesion receptors studied, only VCAM-1 expression was reduced by a mast cell membrane-stabilizing agent, perhaps because of activation of the venous endothelium during harvest prior to ketotifen exposure. However, ketotifen also augmented NOS-2 expression, increased tissue cGMP levels in response to nitroglycerin. These actions may improve vascular homeostasis in the venous graft, suggesting the possibility that this strategy may improve long-term graft patency.

Anticoagulants↗
PubMed1999

Improved survival in patients with acute myocarditis using external pulsatile mechanical ventricular assistance.

BACKGROUND: Acute myocarditis remains a disease with a variable clinical course, from full ventricular recovery to complete heart failure; to date, few cases have been reported that describe the efficacy of temporary mechanical ventricular assistance for its treatment. METHODS: We evaluated the voluntary world registry with the use of an external pulsatile ventricular assist device (the ABIOMED BVS 5000 [BVS]) for acute myocarditis to determine the impact of mechanical ventricular assistance on outcome. Variables analyzed included patient demographics, serum chemistries, and overall hemodynamics prior to BVS, while on BVS support, and after BVS explanation. Postoperative parameters included re-operation, bleeding, respiratory failure, renal failure, and infections, neurologic, or embolic events. RESULTS: Eighteen patients in the ABIOMED world registry underwent BVS implantation for myocarditis; 11 (61.1%) had complete pre-operative and hemodynamic data for analysis. Patients were supported for 13.2 +/- 17.0 days, after which time 7 (63.6%) patients survived to explanation of the device and 2 (18.2%) underwent transplantation. Elevated admission serum chemistries (blood ureanitrogen [BUN], creatinine, transaminases) and hemodynamics (central venous pressure [CVP], mean pulmonary arterial pressure [PAP], pulmonary capillary wedge pressure [PCW], cardiac index [CI], all normalized during the period of device support. Estimated ejection fractions in the 7 explanted patients ranged between 50 to 60% at routine evaluation 3 years after device removal. CONCLUSIONS: Temporary mechanical ventricular assistance represents an efficacious therapy for acute myocarditis in patients with hemodynamic decompensation despite maximal medical therapy. Failure to achieve full ventricular recovery while on device support still allows for other surgical alternatives, including implantation of a long-term implantable ventricular assist device, or cardiac transplantation.

Acute Disease↗
PubMed1999

Arginine vasopressin in the management of vasodilatory hypotension after cardiac transplantation.

Vasodilatory hypotension requiring the administration of catecholamine pressors may occur following cardiopulmonary bypass. We investigated the hemodynamic response to arginine vasopressin (AVP) in 20 patients who developed vasodilatory hypotension after cardiac transplantation. In this cohort, AVP infusion (0.1 U/min) significantly increased mean arterial pressure and decreased norepinephrine requirements, allowing rapid discontinuation of norepinephrine infusions in 7 patients. Judicious use of this novel agent in appropriately selected patients may minimize end-organ sequelae of hypotension and high-dose catecholamine therapy.

Arginine Vasopressin↗
PubMed1999

Development of an infection-resistant LVAD driveline: a novel approach to the prevention of device-related infections.

BACKGROUND: Infection remains the single most important challenge to extended left ventricular assist device (LVAD) use and often arises from the percutaneous driveline exit site. We evaluated the ability of an LVAD driveline prototype impregnated with chlorhexidine, triclosan, and silver sulfadiazine to resist bacterial and fungal colonization. METHODS: The spectrum and duration of antimicrobial activity were evaluated in vitro by daily transfer of driveline segments embedded on agar plates inoculated with 10(8) colony-forming units (CFU) of Staphylococcus aureus (S. aureus), Staphlococcus epidermidis, Enterobacter aerogenes, Psuedomonas aeruginosa, and Candida albicans, and then measuring zones of inhibition around the sample subsequent to 24 hours of incubation at 37 degrees C. Antimicrobial activity was demonstrated against all organisms for greater than 14 days, and for over 21 days for gram-positive bacteria. To demonstrate in vivo efficacy of the treated driveline, 3-cm segments of driveline were implanted in the dorsal and ventral surface of rats. The exit site was inoculated with 10(6) CFU of S. aureus. After 7 days, driveline segments were aseptically explanted and assayed for bacterial colonization and retention of antimicrobial activity. One hundred percent of control segments were colonized (10(5) CFU S. aureus/cm) as against 13% of the test explants (< or = 330 CFU/cm; p < 0.0001). RESULTS: Subcultures of the insertion site and driveline pocket tissue resulted in 10(3) to 10(5) CFU per swab culture for control rats and 0 to 10(2) CFU/swab for test animals. Test drivelines retained 80% of anti-S. aureus activity. Gross and histological examination of the driveline and surrounding pocket revealed minimal tissue reactivity with positive signs of tissue ingrowth. CONCLUSION: An antimicrobial driveline may prevent early infections and facilitate ingrowth of tissue to provide long-term stability and protection against late infection.

Animals↗
PubMed1999

A study of the effect of energy healing on in vitro tumor cell proliferation.

This study examined the effect of energy healing on in vitro tumor cell growth using the cell culture model similar to that embraced by oncologists to assess the effect of chemotherapeutic agents. After selecting an energy healer based on his ability to influence this model, we assessed the effects of energy treatment compared to cells left at ambient temperature and to a control treatment consisting of a medical student mimicking the healer. A chi-square test comparing a medical student's and the practitioner's ability to inhibit tumor cell growth by 15% associates our practitioner with inhibition of tumor cell proliferation (p = 0.02). We also found that the magnitude of change was too close to the assay's intrinsic margin of error, thus making our quantitative data difficult to interpret. Although energy healing appears to influence several indices of growth in in vitro tumor cell proliferation, these assays are limited in their ability to define and prove the existence of this phenomenon. More sensitive biological assays are needed for further study in this field.

Analysis of Variance↗
PubMed1999

Surgical management of the patient with an implanted cardiac device: implications of electromagnetic interference.

OBJECTIVE: To identify the sources of electromagnetic interference (EMI) that may alter the performance of implanted cardiac devices and develop strategies to minimize their effects on patient hemodynamic status. SUMMARY BACKGROUND DATA: Since the development of the sensing demand pacemaker, EMI in the clinical setting has concerned physicians treating patients with such devices. Implanted cardiovertor defibrillators (ICDs) and ventricular assist devices (VADs) can also be affected by EMI. METHODS: All known sources of interference to pacemakers, ICDs, and VADs were evaluated and preventative strategies were devised. RESULTS: All devices should be thoroughly evaluated before and after surgery to make sure that its function has not been permanently damaged or changed. If electrocautery is to be used, pacemakers should be placed in a triggered or asynchronous mode; ICDs should have arrhythmia detection suspended before surgery. If defibrillation is to be used, the current flow between the paddles should be kept as far away from and perpendicular to the lead system as possible. Both pacemakers and ICDs should be properly shielded if magnetic resonance imaging, positron emission tomography, or radiation therapy is to be used. The effect of EMI on VADs depends on the model. Magnetic resonance imaging adversely affects all VADs except the Abiomed VAD, and therefore its use should be avoided in this population of patients. CONCLUSIONS: The patient with an implanted cardiac device can safely undergo surgery as long as certain precautions are taken.

Clinical Protocols↗
PubMed1999

Current status and future directions of minimally invasive cardiac surgery.

The impetus to reduce the trauma of surgery witnessed over the past decade in all fields of surgery has recently extended into the cardiac surgical arena; however, unlike other specialties, the invasiveness of cardiac surgery can be reduced by limiting the size of incisions and by avoiding cardiopulmonary bypass. This article reviews the rationale, clinical experience, and outcomes of the minimally invasive approaches to cardiac surgery that have evolved over the past 2 years and glimpses into the future of this rapidly evolving field.

Cardiac Surgical Procedures↗