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M Adiseshiah

Publications and source records attributed to M Adiseshiah.

At least 19 recordsLinked to original sources
PubMed2004

Aneurysmal hypertension and its relationship to sac thrombus: a semi-qualitative analysis by experimental fluid mechanics.

OBJECTIVES: To ascertain the effect of aneurysm thrombus and luminal diameter on arterial blood pressure within the abdominal aortic aneurysm lumen and at the sac wall. METHODS: A life-like abdominal aortic aneurysm was incorporated in a pulsatile flow unit, using systemic blood pressure settings of 140/100 mmHg and 130/90 mmHg (denoted the high and low settings, respectively). Aneurysm sac pressure was measured in the absence of thrombus within the sac. This was repeated after a thrombus analogue (gelatine) was introduced into the aneurysm model in an asymmetric fashion. Luminal and sac wall pressures were compared to the systemic pressure, and to each other, in both blood pressure settings. Statistical analysis was performed using ANOVA in Minitab 13. RESULTS: In the empty sac, the luminal and sac wall pressures were identical to the systemic pressures at the high and low settings. After introduction of thrombus, pressure was transmitted in a monophasic pulsatile fashion, measuring 166/142/151 mmHg (SP/DP/MP) at the sac wall, while the corresponding intraluminal pressure was 164/136/145 mmHg (p<0.001, high setting). By contrast, in the low setting, these readings were 157/133/141 (sac wall) and 160/128/138 mmHg (lumen; p<0.001). The sac wall pressures were significantly higher than the luminal pressures for both high and low settings (p<0.001). CONCLUSIONS: Thrombus has a significant effect on the intraaneurysmal lumen itself and causes localised hypertension with high intraluminal pressures. The differences between the sac wall/luminal pressures may affect regional aneurysm wall biomechanics, but needs further study.

Aortic Aneurysm, Abdominal↗
PubMed2004

Intrasac pressure waveforms after endovascular aneurysm repair (EVAR) are a reliable marker of type I endoleaks, but not type II or combined types: an experimental study.

PURPOSE: To ascertain the nature of the pressure wave transmitted through aneurysm thrombus and the changes produced after endovascular repair and the development of type I and II endoleaks. METHODS: A 25 mm Talent endovascular graft was deployed in a latex model of an abdominal aortic aneurysm, which was incorporated in a pulsatile flow unit. The graft was surrounded by thrombus analogue to simulate conditions in vivo. Pressure waveforms in the sac were captured over 5s at 1000 Hz in these settings: (i) no endoleaks (baseline), after introduction of (ii) type I (iii) type II and (iv) combined type I and II endoleaks. The arterial blood pressure settings used were 140/100 and 130/90 mmHg, denoted the high and low settings, respectively. ANOVA in Minitab 13 was applied for statistical analysis. RESULTS: Pulsatile waveforms were transmitted through the thrombus. Intrasac pressure after stent-grafting reduced to 110/107, 99/96 mmHg (p<0.001) (high, low settings, respectively). Introduction of a type I endoleak caused this to rise to 120/112, 115/107 mmHg (p<0.001, vs. baseline); after producing a type II endoleak these were 101/98, 91/88 mmHg (p<0.001, vs. baseline). A combined type I and II endoleak produced intrasac pressures identical to that of a type I endoleak. CONCLUSIONS: Intrasac pressure waveforms following EVAR are easily defined following a type I endoleak. Waveforms obtained following type II endoleak simulation resemble the baseline waveform in an attenuated form. Intrasac pressures are, therefore, a reliable marker for type I, but not a type II endoleak. In the case of a combined endoleak, the type I endoleak waveform effectively masks that of the type II. Intrasac thrombus faithfully transmits intrasac pressures.

Aortic Aneurysm, Abdominal↗
PubMed2003

Secondary intervention following endovascular repair of abdominal aortic aneurysm: a single centre experience.

AIMS: We aim from a review of our early and late experience of secondary intervention for technical failures, to examine and describe the impact of endovascular and open interventions. METHODS: 108 Abdominal Aortic Aneurysms (AAAs) repaired endoluminally between 1995-2001 were analysed. In our early experience, during 1995/96 home made pre-expanded polytetrafluoroethylene grafts fixed with Palmaz stents were used (n = 26). In our later experience, 1997/2001 Talent (n = 70) or Zenith endografts (n = 12) were used. All cases underwent spiral CT at 5 days and 6 monthly intervals post-op. Angiography was performed when further intervention was intended. All technical failures requiring intervention or not were studied. RESULTS: There were 28 (26%) technical failures identified of which 14 of 26 (54%) occurred in our early experience, and 14 of 86 (16%) occurred in our later experience (p < 0.05). Eleven in all required open conversion at the time of endovascular repair. Our study cohort were the remaining 17 cases requiring secondary intervention, seven were from our early experience and 10 from our later experience. There were 12 endoleaks, including two as a result of graft migration, two graft occlusions, two graft distortions and one graft infection. Overall 10 (66%) technical failures were treated by endoluminal repair and seven (34%) by open methods. However, in our later experience significantly more endoluminal techniques (80%) were used (p < 0.05). CONCLUSIONS: Technical failure rates were significantly higher in our earlier experience. Open repair, which was a feature of our early experience, has been avoided over the final 3 years. Instead, endoluminal techniques were used without further morbidity or mortality. Aneurysm rupture has not so far been experienced in this experience.

Adult↗
PubMed2002

Cardiac arrest after administration of Omnipaque radiocontrast medium during endoluminal repair of abdominal aortic aneurysm.

We describe a case of acute cardiovascular collapse in a patient with end-stage renal failure undergoing endoluminal repair of an abdominal aortic aneurysm. The 61-yr-old man suffered cardiac arrest shortly after administration of radiocontrast medium (Omnipaque), during deployment of the endovascular device. He had received the same contrast solution for diagnostic angiography on the previous day. He was successfully resuscitated and recovered completely. The differential diagnosis and management are discussed.

Aortic Aneurysm, Abdominal↗
PubMed2001

Micromovements at the aortic aneurysm neck measured during open surgery with close-range photogrammetry: implications for aortic endografts.

PURPOSE: To describe the motion of abdominal aortic aneurysm (AAA) as a first step toward determining if stent-graft migration may be due to propulsive movements at the neck. METHOD: In an initial laboratory validation test, a silicone AAA model was imaged with a stereo-pair configuration of calibrated digital cameras using retro-reflective and ink dot surface targets. This technique was then applied to 4 aneurysm necks imaged at open surgery. In each case the paired images were measured and analyzed to produce sequences of accurate three-dimensional (3-D) surface models of the anterior aspect of the aortic neck. Engineering techniques were used to visualize and identify differences between the generated surfaces, allowing changes in shape of the aortic wall to be determined. RESULTS: The correlation between stereoscopic digital imaging with electronic caliper measurements of linear dimensions was accurate, irrespective of the type of surface targets used (r2 = 0.98). The AAA neck demonstrated complex 3-D movements that ranged from 1.0 to 1.5 mm in the radial direction to 0.6 to 1.0 mm along the longitudinal axis, with a 0.44 to 0.59-mm rotational component (p < 0.05). CONCLUSIONS: This pilot study raises questions about the validity of accepted models of arterial wall movements and compliance in which rotation has not been described. The technique used to measure dynamic neck morphology appears promising as a means to further define the mechanical parameters of the human aorta, which may assist in designing stent-grafts.

Aged↗
PubMed2000

For debate: concomitant critical coronary arterial disease and abdominal aortic aneurysm--timing of corrective procedures.

BACKGROUND: The high prevalence of coronary artery disease (CAD) in patients with abdominal aortic aneurysm (AAA) is responsible for most , 30-day mortality and morbidity in elective repair of AAA. The continuing debate regarding staged or combined surgery for AAA and CAD (coronary artery bypass grafting -CABG) in the small number of patients with critical degrees of both co-morbidities has not had a significant impact on the greater mortality and morbidity when the AAA repair is undertaken using the standard open operation. PATIENTS: We report four cases with these combined pathologies which we have managed over the last 30 months during which time we have developed techniques of endolumenal repair of AAA. CONCLUSIONS: Whilst it is not possible to make firm recommendations regarding management strategy owing mainly to a lack of large series reporting this unusual combination of co-morbidities, the options are debated on the basis of published anecdotal evidence as well as our own case reports. We suggest that if the AAA is non-tender and/or 5.5-8.0 cm, the staged approach is appropriate. If the AAA is tender and/or > 8.0 cm, a combined approach may be a better option in order to avoid the risk of AAA rupture during the interval between the operations. Endolumenal repair of AAA offers a further option for the staged and combined approach, and may be less invasive than the standard open surgery for AAA repair.

Aged↗
PubMed2000

A prospective study of changes in aneurysm and graft length after endovascular exclusion of AAA using balloon and self-expanding endograft systems.

PURPOSE: Longitudinal shrinkage of aneurysms post-endovascular repair, employing unvalidated measurement techniques has been held to account for endograft disruption. In this study we record changes in aneurysm length, diameter and volume using the gold standard of calibrated spiral CT angiography (SCTA). METHOD: From 179 patients with AAA scanned by SCTA, 68 were selected for endografting. Twenty-seven had PTFE home-made prostheses while 41 patients had Talent endografts. SCTA was performed on the fifth postoperative day and 6-monthly intervals thereafter. The distance between the lowest renal artery and the aortic bifurcation (VBL - vertical body length) and the luminal centre line length (LCL) were measured. Maximal sac diameters and volumes were recorded using 3DCT reconstruction. RESULTS: Significant increase was noted in VBL (3.2) mm for PTFE-treated patients accompanied by an increase in sac volume at day 5 (12.5 ml). No changes in LCL or maximal diameters were evident. At 1.5 years further lengthening of both VBL (6.4 mm) and LCL (9.3 mm) was unaccompanied by sac diameter/volume changes. Talent patients - no changes in VBL or LCL were evident. Volumes and maximal AP and transverse diameters showed marked shrinkage: AP -11. 2 mm; transverse -2.6 mm; volumes by -35.5 ml at 6 months. CONCLUSION: With PTFE increase in VBL but not graft length, without concurrent changes in maximal diameters at day 5, is commensurate with increase in sac volume; after 1.5 years graft lengthening overtakes aortic lengthening. In Talent patients VBL/graft length remained unchanged. There is no evidence for longitudinal aneurysmal contracture. Volumes and maximal diameters for the Talent endograft but not for PTFE show shrinkage.

Aged↗
PubMed2000

Differing morphological changes following endovascular AAA repair using balloon-expandable or self-expanding endografts.

PURPOSE: To determine whether changes in aneurysm morphology after endovascular abdominal aortic aneurysm (AAA) repair differ according to the type of endograft (self-expanding versus balloon-expandable). METHODS: Among 88 patients with AAA treated with either homemade polytetrafluoroethylene (PTFE) aortomonoiliac endografts or Talent stent-grafts, 30 patients (24 males; mean age 73 years, range 55-93) were selected for this study based on a >2-year follow-up and freedom from endoleak or conversion. Of these, 12 had PTFE endografts and 18 Talent devices. All patients had spiral computed tomographic angiography with 3-dimensional reconstruction at 5 days posttreatment and 6-month intervals thereafter. Neck dimensions (length and diameters at 3 levels) were measured, along with volumes and maximal diameters of the sac and lengths of the aneurysm and endograft. Intra- and interobserver errors were <5% for linear and volume measurements. RESULTS: Both groups had an initial 20-mL increase in median volume (p = 0.02) followed, only in Talent patients, by marked shrinkage at 6 months (-87.4 mL; p = 0.09). PTFE patients had no further changes in sac volume. Maximal sac diameters reflected volumes, but only after day 5. PTFE patients had an immediate increase (p = 0.03) in aneurysm neck diameters, which then remained stable. Talent patients had continuing increases in diameter to 6 months (p < 0.05), with no change thereafter. Length changes were not significant in either group. PTFE patients had an increase in median aneurysm length at day 5 (+3.2 mm, p = 0.04) and again at 1.5 years (+6.4 mm, p = 0.03). Endograft length slowly increased (+18.7 mm) over 1.5 years (p = 0.02). Talent patients had no length changes in the device or aneurysm. CONCLUSIONS: Aneurysm morphology appeared to alter according to the type of endograft deployed. With PTFE endografts, aneurysm volume does not change, whereas impressive sac shrinkage occurs in conjunction with the Talent system. Aneurysm/graft lengths increase with unsupported stent-grafts. Neck diameter increases immediately with balloon-expandable endografts and then remains constant. In the self-expanding models, neck diameter increases at 6 months but not thereafter.

Aged↗
PubMed2000

The abdominal aortic aneurysm sac after endoluminal exclusion: a medium-term morphologic follow-up based on volumetric technology.

PURPOSE: The purpose of this study was to evaluate the role of three-dimensional spiral computed tomographic angiography (SCTA) for the assessment of the feasibility and results of endoluminal repair of infrarenal abdominal aortic aneurysm. METHODS: Laboratory studies: Phantom glass aneurysms, filled with contrast, underwent SCTA. The correlation between SCTA and laboratory measurements of linear dimensions and volumes was highly accurate (r(2) = 1.0). CLINICAL STUDIES: From the first 7 patients that were suitable for endoluminal repair, the correlation between SCTA and angiocatheter measurements was 0.85 to 0.99 (P <.04), but there was poor agreement between individual values. As determined from the measurements by 2 experienced investigators, intraobserver and interobserver errors for volume calculation in 12 randomly chosen scans from a total of 120 scans were 5.7 and 4.4 mL, respectively (range of volumes, 100-403 mL). The conditions of 53 patients were judged suitable for endoluminal repair of which 30 patients reached 1 year or more follow-up. The median aneurysm neck length and diameter were 24.5 mm (range, 11.5-60.8 mm) and 23.4 mm (18.3-31.5 mm), respectively. The fate of the sac after endografting by two techniques (pre-expanded polytetrafluoroethylene [PTFE] fixed with Palmaz stents and endografts) was defined with three-dimensional SCTA. RESULTS: The sac volume after endografting by pre-expanded PTFE (n = 12 patients) showed a significant median increase (P =.02) from 129 mL before surgery to 141 mL at 5 days after the operation with no change at 6 (139 mL), 12 (137 mL), and 18 (159 mL) months later. With the endografts (n = 18), there was an initial increase in median volume at 5 days (179-194 mL; P =.02) and then a significant shrinkage at 6 (148 mL; P =.012) and 12 (94.9 mL; P =.02) months. CONCLUSION: Three-dimensional SCTA has been validated and is both precise and reliable. Interobserver and intraobserver errors are within acceptable ranges. Angiocatheter measurements are less accurate and may give misleading information when used for patient selection and endograft construction. The sac volume increased after endografting and later shrank in patients who were treated with endografts, but not in those patients treated with pre-expanded PTFE. We propose that three-dimensional SCTA should be regarded as the gold standard for linear and volumetric measurement for infrarenal abdominal aortic aneurysm.

Aortic Aneurysm, Abdominal↗
PubMed1998

Comparison of duplex imaging and arteriography in the evaluation of lower limb arteries.

BACKGROUND: The aim of this study was to assess the accuracy of duplex imaging, compared with arteriography, in detecting arterial disease distal to the renal arteries. METHODS: Some 177 legs were studied in 90 patients (59 men, 31 women; median age 68 years) with peripheral arterial disease. Each patient had conventional intra-arterial angiography and duplex ultrasonography. Each leg was divided into 17 arterial segments, and the disease in each segment was quantified by measuring the peak systolic velocity ratio across any arterial lesion that was identified. RESULTS: Compared with angiography, duplex imaging was able to detect arterial disease with an overall sensitivity of 92 per cent, specificity of 99 per cent, positive predictive value 91 per cent and negative predictive value 100 per cent, and with a kappa value of 0.87 (95 per cent confidence interval (c.i.) 0.81-0.93). Duplex was able to determine the length of the arterial lesion with a sensitivity of 89 per cent and a specificity of 98 per cent with a kappa value of 0.88 (95 per cent c.i. 0.86-0.90). When the surgeon's final management decision concerning each vascular lesion was used as the reference, duplex and arteriography were equivalent, with an accuracy of 84 per cent and 85 per cent respectively in identifying the management used. CONCLUSION: Duplex ultrasonography is reliable in detecting arterial lesions in peripheral arteries and could be used routinely in the initial evaluation of patients with lower limb arterial disease.

Aged↗