Device-related Morbidity Research Articles

In Vivo Preclinical Anticoagulation Regimens After Implantation of Ventricular Assist Devices

Ventricular assist devices (VADs) have demonstrated successfully their ability to treat failing circulation of patients with end-stage heart failure. Among the main obstacles with these VADs is thromboembolic events that increase device-related morbidity and mortality. Prior to the clinical application of any newly developed VAD, the feasibility of the device is tested on animal models. Animal species have different hemostatic properties than human patients, and this factor creates a margin of error when comparing the occurrence of VAD-induced thrombosis in an animal versus a human. This detailed literature review provides a thorough documentation of various preclinical anticoagulation protocols used to date, including their outcomes and recommendations for future anticoagulation management strategies. In summary, the outcomes favor a sheep or pig model over other animal models, and discourage the application of a single anticoagulative agent to improve outcomes with any of the currently available devices.

Hemodynamic effects of partial ventricular support in chronic heart failure: Results of simulation validated with in vivo data

Current left ventricular assist devices are designed to provide full hemodynamic support for patients with end-stage failing hearts, but their use has been limited by operative risks, low reliability, and device-related morbidity. Such concerns have resulted in minimum use of left ventricular assist devices for destination therapy. We hypothesize that partial circulatory support, which could be achieved with small pumps implanted with less-invasive procedures, might expand the role of circulatory support devices for treatment of heart failure. We examine the hemodynamic effects of partial left ventricular support using a previously described computational model of the cardiovascular system. Results from simulations were validated by comparison with an in vivo hemodynamic study. Simulations demonstrated that partial support (2-3 L/min) increased total cardiac output (left ventricular assist device output plus native heart output) by more than 1 L/min and decreased left ventricular end-diastolic pressure by 7 to 10 mm Hg with moderate-to-severe heart failure. Analyses showed that the hemodynamic benefits of increased cardiac output and decreased left ventricular end-diastolic pressure are greater in less-dilated and less-dysfunctional hearts. Both the relationships between ventricular assist device flow and cardiac output and ventricular assist device flow and left atrial pressure predicted by the model closely approximated the same relationships obtained during hemodynamic study in a bovine heart failure model. Results suggest that a pump with a flow rate of 2 to 3 L/min could meaningfully affect cardiac output and blood pressure in patients with advanced compensated heart failure. The development of small devices capable of high reliability and minimal complications that can be implanted with less-invasive techniques is supported by these findings.

A model for intratumoural chemotherapy in the rat brain.

To achieve the best reproducibility in rat brain tumour models several injection techniques have been used. Although stereotactic cell injections have proved to be effective and reliable, they are expensive and time consuming. A new permanently implanted device is presented here. It allows precise cell delivery for best tumour reproducibility, and it can be left in place for future injections at the exact same location, such as intratumoural chemotherapy. A Teflon tube was mounted on a disc, inserted into the rat brain and sealed to the skull. The device was tested in two rat strains (Wistar and New Zealand Nude rats) with two different glioma cell lines (9L and C6). Rats were treated with placebo to determine if repeated treatments had an effect on the device placement, or if device-related morbidity was induced. Analysis of brain sections showed that the device path was always within the tumour. The device never moved or came off the scalp. Both Wistar rats and NZ nude rats tolerated the device well. No morbidity or mortality was observed, regardless of the presence of the device; no infections were seen. Biocompatible, non-irritating and well tolerated, such a device can be used for reproducible tumour cell injections and repeated intralesional delivery of drugs.

Transcutaneously tunneled central venous lines in cancer patients: an analysis of device-related morbidity factors based on prospective data collection.

Long-term transcutaneous tunneled central venous catheters are frequently placed in cancer patients, accounting for significant costs and morbidity. Factors influencing outcome, though, are poorly studied. Between June 1991 and June 1993, 923 central venous tunneled catheters were placed in 791 patients at Memorial Sloan-Kettering Cancer Center. Placement-, device-, and patient-related parameters were charted prospectively (median follow-up: 120 days) and correlated to device-specific outcome events. Median patient age was 28.5 years (range: 0.025 - 84.5). Disease distribution included hematologic malignancies (64.7%), solid tumors (30.4%), and others (4.9%). Primary indications for line access included chemotherapy (72.8%), bone marrow transplantation (18.7%), total parenteral nutrition (6.4%), and drug administration (2.1%). There were 11 insertion complications (1.2%), including insertion failure (n = 6), hemorrhage (n = 4), and malposition (n = 1). Subsequent to placement, a proven or suspected device-specific complication occurred in 540 lines (58.5%). Per 10,000 catheter days, there were 17.6 infection episodes, 8.1 thrombotic complications, 6.9 instances of catheter breakage, 3.5 accidental or inadvertent cases of displacement, and 0.6 device leaks. Reasons for line removal or other termination of follow-up were patient's death (32.1%), treatment end (28%), infection (19.6%), suspected infection (6.3%), displacement (6.8%), thrombosis (3.1%), leak (1%), and others (3.1%). Median device-specific duration was 365 days, compared with a median complication-free device-specific duration of 167 days (P < 0.0001), reflecting a highly significant device salvage rate after complications. Catheter tip position emerged as the dominant independent prognostic factor for reduced device-specific duration or complication-free device-specific duration. Transcutaneous tunneled central venous lines can be placed safely, with a considerable incidence of subsequent device-specific complications, but a high salvage rate. Factors determining outcome are related to device placement, as well as the patient's disease status. In this study, patients alive 90 days after catheter placement had a 37% chance for a device complication, with a 20% chance for device loss. Future analyses of intermediate-term intravenous access should employ the measurement of device-specific outcome as a reference parameter to assess clinical results.

Subcutaneously implanted central venous access devices in cancer patients

Long term intravenous access is a common requirement for cancer patients. This analysis was designed to determine device-related morbidity and factors predictive of poor long term outcome for patients with subcutaneous single lumen intravenous access ports. Six hundred eighty patients who underwent subcutaneous intravenous port placement between June 1987 and May 1989 at Memorial Sloan-Kettering Cancer Center were followed prospectively until port removal, death, or a maximum of 1960 days. Indications for and circumstances of placement, patient diagnoses, patient demographics, and subsequent courses of treatment were recorded, as well as technical and microbiologic device-related complications. Total, device specific, and complication free device durations were calculated. The median patient age was 52.4 years (range, 1.6-83.9 years). The female-to-male ratio was 1.5 to 1. Cancer diagnoses included solid organ tumors (84%), leukemia (4%), lymphoma (11%), and others (1%). Indications included access for systemic chemotherapy (98%), total parenteral nutrition (0.5%), and others (1.5%). One insertion complication and six insertion failures occurred, without mortality. The estimated mean overall actuarial device specific duration was 1191 days (range, 2-1960 days). Actuarial mean complication free, device specific duration was 952 days. Complications included sepsis (n = 31; 4.4%), site infection (n = 31; 4.4%), and accessibility failures such as thrombosis and leakage (n = 40, 5.7%). Reasons for end of port duration were patient death (72.4%), end of treatment (13.5%), functional failure or intractable infection (11.2%), and others (2.9%). Independent factors correlating with decreased port specific, complication free duration included placement site, age, tumor type, and catheter tip position. Subcutaneous intravenous access ports in cancer patients are safe and well tolerated. Long term device duration is primarily influenced by patient survival. In this study, 90% of patients alive at 1 year and 70% of patients alive at 4 years had a functional port.

Subcutaneously implanted central venous access devices in cancer patients

BACKGROUND Long term intravenous access is a common requirement for cancer patients. This analysis was designed to determine device-related morbidity and factors predictive of poor long term outcome for patients with subcutaneous single lumen intravenous access ports. METHODS Six hundred eighty patients who underwent subcutaneous intravenous port placement between June 1987 and May 1989 at Memorial Sloan-Kettering Cancer Center were followed prospectively until port removal, death, or a maximum of 1960 days. Indications for and circumstances of placement, patient diagnoses, patient demographics, and subsequent courses of treatment were recorded, as well as technical and microbiologic device-related complications. Total, device specific, and complication free device durations were calculated. RESULTS The median patient age was 52.4 years (range, 1.6-83.9 years). The female-to-male ratio was 1.5 to 1. Cancer diagnoses included solid organ tumors (84%), leukemia (4%), lymphoma (11%), and others (1%). Indications included access for systemic chemotherapy (98%), total parenteral nutrition (0.5%), and others (1.5%). One insertion complication and six insertion failures occurred, without mortality. The estimated mean overall actuarial device specific duration was 1191 days (range, 2-1960 days). Actuarial mean complication free, device specific duration was 952 days. Complications included sepsis (n = 31; 4.4%), site infection (n = 31; 4.4%), and accessibility failures such as thrombosis and leakage (n = 40, 5.7%). Reasons for end of port duration were patient death (72.4%), end of treatment (13.5%), functional failure or intractable infection (11.2%), and others (2.9%). Independent factors correlating with decreased port specific, complication free duration included placement site, age, tumor type, and catheter tip position. CONCLUSIONS Subcutaneous intravenous access ports in cancer patients are safe and well tolerated. Long term device duration is primarily influenced by patient survival. In this study, 90% of patients alive at 1 year and 70% of patients alive at 4 years had a functional port. Cancer 1997; 79:1635-40. © 1997 American Cancer Society.