Balloon Failures Research Articles

Effect of Ethylene Oxide and Gamma (γ-) Sterilization on the Properties of a PLCL Polymer Material in Balloon Implants.

Poly-l-lactide-co-ε-caprolactone (PLCL) is a unique polymer containing both polylactic acid and poly-ε-caprolactone (PCL) chain units, and thus it has better flexible and biodegradable properties. Based on these unique properties of PLCL, we have developed balloons that are now widely used in treating major medical problems [Biomaterials2016,105, 109–116]. One of the most important considerations needed for balloons is to ensure that the material properties remain similar after undergoing ethylene oxide (EtO) or gamma (γ-) sterilization treatments. From the biotechnological point of view, we focused on analyzing the vital molecular properties of the PLCL material after sterilization, such as changes in crystallinity, molecular weight distributions (Mw, Mn, and polydispersity index), and inherent viscosity (η). Analysis of the data reveals that EtO sterilization does not engender any change in crystallinity, melting temperature (Tm), molecular weights, and η of the polymer. On the contrary, γ-radiations induce chain scission and consequential decrease of ∼33 and ∼15% in molecular weights and η values, respectively. Based on our observations, we recommend EtO sterilization instead of γ-radiation for PLCL. This ensures prolonged stability of the polymer against degradation in a biological environment, long-shelf life, and absolute assurance that balloon failures do not occur after implantation.

Analysis of Reported Balloon Malfunctions and Proposed Rescue Strategy for Malfunction during Airway Dilation.

Objective The rate of balloon dilator failure is unknown, and a rescue strategy for device malfunction has not been established. The purposes of this investigation were to determine the approximate number of balloon failures in the gastrointestinal tract and airway, evaluate the parameters required to rupture balloon dilators, and develop a rescue strategy to efficiently reestablish airway patency. Study Design Retrospective cohort and basic medical research. Setting Academic tertiary care medical center. Subjects and Methods The Manufacturer and User Facility Device Experience database was queried for adverse events associated with tracheal and esophageal dilators between January 1, 2014, and January 1, 2017. A bench-top model of airway stenosis was developed, and optimal conditions for the safe removal of a malfunctioning dilator were assessed (2, 4, 6 atm). Results There were 420 reported balloon malfunctions, including 104 cases with deflation/removal issues. The bench-top model determined that device rupture allowing for immediate removal occurs with needle puncture at balloon pressures ≥8 atm. Balloons inflated to 6 atm required a median of 17.5 seconds (range, 0-55.3) for removal, in comparison with 30.2 seconds (range, 7.1-87.5) at 2 atm ( P > .05). Conclusion Balloon dilator malfunction is a significant problem that practitioners must be prepared for. Pressure ≥8 atm (~33% overinflation) is required to consistently cause complete balloon dilator rupture via needle puncture. While counterintuitive, increasing the inflation pressure of a malfunctioning balloon (8-10 atm) may expedite rupture and safe removal. A rescue strategy for balloon malfunction is proposed.

Beyond the balloon: excimer coronary laser atherectomy used alone or in combination with rotational atherectomy in the treatment of chronic total occlusions, non-crossable and non-expansible coronary lesions

To establish success and complication rates of excimer laser coronary atherectomy (ELCA) in a contemporary series of patients with balloon failure during percutaneous coronary intervention (PCI) of both chronic total occlusions (CTO) and lesions with distal TIMI 3 flow. We identified 58 cases of balloon failure treated with ELCA±rotational atherectomy (RA) over four years, representing 0.84% of all PCI performed in our centre during this period. Balloon failures were classified according to: (i) mechanism of balloon failure; and (ii) whether this occurred in the context of treating a CTO. ELCA was performed following balloon failure using the CVX-300 Excimer Laser System and a 0.9 mm catheter with saline flush. For the entire cohort, procedure success was achieved in 91% (with ELCA successful: alone in 76.1%, after RA failure in 6.8% and in combination with RA for 8.6%). Only in one case did RA succeed where ELCA had failed. There were four procedure-related complications, including transient no-reflow, side branch occlusion and two coronary perforations, of which one was directly attributable to ELCA and led to subsequent mortality. ELCA provides safe and effective adjunctive therapy in contemporary PCI to treat lesions associated with balloon failure due to an inability either to cross the lesion or to expand a balloon sufficiently to permit stenting. ELCA was successful in the majority of these selected cases when used independently with further effectiveness achieved when combined with RA or after RA failure.

Overview of the NASA balloon R&D program

The catastrophic balloon failures during the first half of the 1980's identified the need for a comprehensive and continuing balloon research and development (R&D) commitment by NASA. Technical understanding was lacking in many of the disciplines and processes associated with scientific ballooning. A comprehensive balloon R&D plan was developed in 1986 and implemented in 1987. The objectives were to develop the understanding of balloon system performance, limitations, and failure mechanisms. The program consisted of five major technical areas: structures, performance and analysis, materials, chemistry and processing, and quality control. Research activities have been conducted at NASA/Goddard Space Flight Center (GSFC)-Wallops Flight Facility (WFF), other NASA centers and government facilities, universities, and the balloon manufacturers. Several new and increased capabilities and resources have resulted from this activity. The findings, capabilities, and plans of the balloon R&D program are presented.

NASA balloon design and flight: Philosophy and criteria

The catastrophic balloon failures during the first half of the 1980's were devastating to the USA scientific ballooning community as well as balloon users from other countries. Confidence in the balloons reached an all time low with success rates of 50% or lower being experienced across all payload ranges. An intensive investigation by the USA National Aeronautics and Space Administration (NASA) was initiated in 1983 to identify the cause(s) of the failures. Findings from the investigation resulted with NASA implementing a new balloon design and flight philosophy for all NASA scientific balloons. The NASA Balloon Program philosophy and criteria for scientific balloon design and flight are presented.

Status of the NASA Balloon Program

In the early 1980's the U.S. National Aeronautics and Space Administration (NASA) Balloon Program was faced with a problem of catastrophic balloon failures. In 1986 a balloon recovery program was initiated. This program included qualification of new balloon films, and investigations into materials, processing, structures and performance of balloons. This recovery program has been very successful. To date, more than 100 balloons manufactured of newly developed films have been flown with unprecedented success. There has been much progress made across the spectrum of balloon related disciplines. A new design philosophy has been developed and is being used for all NASA balloons. An updated balloon reliability and quality assurance program is in effect. The long duration balloon development project has been initiated with the first flight test having been conducted in December 1989 from Antarctica. A comprehensive research and development (R&D) effort has been initiated and is progressing well. The progress, status and future plans for these and other aspects of the NASA program, along with a description of the comprehensive balloon R&D activity, will be presented.

Rotational ablation of coronary artery lesions using single, large burrs.

Previous clinical use of the Rotablator in coronary artery disease has involved a sequential increase in burr sizes up to 2 mm in diameter and has often utilized balloon adjunct to achieve an optimal result. We report our experience and describe our technique using a single, large burr (2.25, 2.5, or 2.75 mm diameter) without balloon assistance. The burr size was selected to approximate 70-90 percent of the apparent normal lumen diameter. Thirty-one patients with 36 lesions of complex morphology (eccentric, irregular, calcified, ulcerated, at bends, at bifurcations, completely occluded, as well as balloon failures) were successfully treated with the Rotablator. Results were assessed by computerized quantitative angiography. The percent diameter stenosis (mean +/- SD) for the group was reduced from 69.8 +/- 11.3% to 30.9 +/- 10% (p less than 0.001). The mean absolute diameter stenosis increased from 0.9 +/- 0.3 mm to 2.2 +/- 0.3 mm (p less than 0.001). Angiographically visible dissections were seen in 4 patients and were uncomplicated in 2. One patient had a non-Q-wave myocardial infarction. A fourth patient had a presumed acute occlusion 36 hr after the procedure, necessitating emergency bypass surgery, but without Q waves on the electrocardiogram or wall-motion abnormalities on the echocardiogram. Nitroglycerin was infused through the Rotablator catheter and has considerably lowered the degree and frequency of spasm. No other acute complications occurred. The mean procedure time using a single burr was shorter than when multiple burrs were used: 56.5 vs. 97.3 min, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angioplasty with 7F guiding catheters

The performance of 7F guiding catheters for percutaneous transluminal coronary angioplasty (PTCA) was investigated in 300 patients. A total of 233 patients had single-vessel PTCA and 67 had multivessel PTCA. Angioplasty was attempted for 371 lesions (141 [38%] in the left anterior descending, 124 [33%] in the right coronary artery, and 95 [26%] in the left circumflex coronary artery or their branches; 10 [3%] in a bypass graft, and one in the left main stem). The mean degree of stenosis was 86 ± 11% (range 60% to 100%). The monorail technique was used in 83%, and balloon-on-a-wire devices were used in 6% of cases. The balloon sizes varied between 2.0 and 4.25 mm. There was a 98% technical success rate for the 325 nontotal lesions. Five could not be crossed with the wire. Exchange to an 8F guiding catheter was done in four cases (1.2%) and yielded success in two of them. In 46 occlusions the success rate was 72%. Nine were failures due to an inability to cross the wire, another two were balloon failures, and in two cases the residual stenosis was >50%. The mean residual stenosis of successful cases was 24 ± 18%. Overall, the primary success rate was 95%. The complications were: in-hospital death in five patients (1.7%); infarction in 12 (4%); emergency bypass surgery in one; and significant inguinal hematoma in five (1.7%). Coronary angioplasty through 7F guiding catheters yields a high success rate with less coronary wedging and a smaller puncture hole.

Status of the NASA continuing investigation of catastrophic balloon failures

Since the beginning of the 1980's, the USA National Aeronautics and Space Administration (NASA) Balloon Program has been besieged with a continuing problem of catastrophic balloon failures. In 1983 NASA conducted an investigation to identify possible causes for the failures and to determine the necessary corrective action(s) to prevent further occurrence of the problem. The investigation indicated the most probable cause of the failures was the balloon material. Subsequent corrective action(s) were taken to eliminate the problem by establishing a material acceptance criteria for balloon film. Although improvements have been noted in certain classes of balloons, the problem of catastrophic balloon failures continues. Efforts continue, to determine the cause(s) of the diminished performance of current balloons, including investigation of the microstructure of present and past balloon film, stress effects and simplified stress modeling including shape studies, and the equipment and procedures used in the manufacture of balloons. Most recently, a special team of experts has been assembled to aid in the investigation of the failure problems and the methods needed for a solution. The findings and status of the continuing investigation along with the future plans for the NASA program are presented.

Recent materials problems relating to catastrophic balloon failures

Balloons fabricated of thin polyethylene materials have provided relatively inexpensive and reliable scientific research platforms for approximately three decades. Reliability of the modern day balloon, as launched by the U.S.A. National Scientific Balloon Facility (NSBF), has been approximately 85%. Recent balloon failures, coupled with an increased occurrence of catastrophic failures, created grave concern over the integrity of the present balloon inventory of the U.S.A National Aeronautics and Space Administration (NASA). An investigative team was established by NASA to review the circumstances surrounding the catastrophic balloon failures, determine the cause and to make recommendations to correct the problem and to prevent its reoccurrence. The most probable cause of failure as determined by the investigation was the polyethylene balloon film, although the film had passed the established standard quality control measures of the film manufacturer. The approach, findings, and conclusions of the investigation are presented along with planned procedures to assure future quality balloon film for NASA balloons.

External caps: An approach to stress reduction in balloons

Recent findings of the catastrophic balloon failures investigation in the U.S.A. indicate that very large gross inflations, in balloons using present design philosophy, over-stress currently available materials. External caps are proposed as an economic approach to reducting those stresses to an acceptable level.

Data Acquisition, Reduction, And Transmission of Atmospheric Electricity Data on High-Altitude Scientific Balloons

The second generation of a microprocessor system used on high-altitude scientific balloons is described. The system performs a variety of functions as a controller, a signal processor, and a scientific processor. Two flights of the system demonstrated its reliability although balloon failures prevented the system being fully tested.

High altitude flights in equatorial regions

A thorough analysis of balloon flights made from Hyderabad, India (Latitude 17°28′N, Longitude 78°35′E), and other equatorial sites has been made. It has been shown that limited success is expected for flights made from equatorial latitudes with balloons made out of natural colour polyethylene film, since the best known balloon film in the world today viz. Winzen Stratofilm is tested for low temperature brittleness only at −80°C., whereas the tropopause temperatures over equatorial latitudes vary between −80°C and −90°C. The success becomes even more critical when flights are made with heavy payloads and larger balloons particularly at night when in the absence of solar radiation the balloon film becomes more susceptible to low temperature brittle failure. It is recommended that in case of capped balloons longer caps should be used to fully cover the inflated protion of the balloon at the higher level equatorial tropopause. It is also advised that the conditions such as wind shears in the tropopause should be critically studied before launching and a day with the tropopause temperature nearer to −80°C should be chosen. Special care also should be taken while handling the balloon on ground and during launching phase. Properties of Winzen Stratofilm have been critically studied and fresh mandates have been recommended on the basis of limiting values of film stresses which caused balloon failures in the equatorial tropopause. It is also emphasized that the data on such flights is still meagre especially for flights with heavy payloads and larger balloons. It has been also shown that it is safest to use balloons made out of grey coloured film which retains its flexibility with the absorption of solar radiation, the success obtained with such balloons so far being 100%. The drawback, however, is that these balloons cannot be used for night flights. Stratospheric wind regimes over Hyderabad are also discussed with a view to determine the period over which long duration flights can be made. The data available, however, is meagre and it is recommended that more frequent special wind ascents be made to collect adequate statistical data from which reliable conclusions could be drawn through critical analysis.

Balloon deflation failure: A hazard of “medical” atrial septostomy

T he four years following Rashkind and Miller’s’ introduction of a technique to create an atria1 septal defect with a balloon-tipped catheter have seen widespread acceptance of this major therapeutic advance.2-4 However, recent reports of complications of the procedure5-7 make it clear that balloon failures constitute a potential threat in every use of such catheters and that operators must be prepared to deal with these complications. This communication describes two instances wherein the balloon could not be deflated following septostomy and offers suggestions for the prevention and management of such failures.