Abdulhameed Aziz

Outcomes of percutaneous endovascular intervention for type II endoleak with aneurysm expansion.

OBJECTIVE Type II endoleak (T2EL) with aneurysm expansion is believed to place patients at risk for aneurysm-related mortality (ARM). Treatment with glue and/or coil embolization of the aneurysm sac, inferior mesenteric artery (IMA), and lumbar branches via translumbar or transarterial approaches has been utilized to ablate such endoleaks, and thus decrease ARM. We evaluated the midterm results of percutaneous endovascular treatment of T2EL with aneurysm expansion. METHODS Single-institution, 5-year (January 2003 to August 2008) retrospective study of all endovascular interventions for T2EL with sac expansion. Blinded, independent review of all available pre- and post-T2EL intervention computed tomography (CT) scans was performed. Aneurysm sac maximal transverse diameters and aneurysm sac growth rates prior to and following T2EL intervention were analyzed. RESULTS Forty-two patients (34 male, eight female; mean age, 75) underwent T2EL intervention at 26 ± 20 months after endovascular aneurysm repair (EVAR) and were subsequently followed for 23 ± 20 months. Seven out of 42 patients (17%) underwent repeat T2EL intervention. Interventions included 44 translumbar sac embolizations, and transcatheter embolizations of nine IMAs and seven lumbar/hypogastric arteries. Aneurysm diameter was 6.1 ± 1.6 cm at EVAR, 6.6 ± 1.5 cm at initial T2EL treatment, and 6.9 ± 1.7 cm at last follow-up. There were no significant differences in the rates of aneurysm sac growth pre- and post-T2EL treatment. At last follow-up imaging, recurrent or persistent T2EL was noted in 72% of patients. Of 42 patients, nine (21%) received operative endoluminal correction of occult type I or type III endoleaks that were diagnosed during the T2EL angiographic intervention. There were no aneurysm ruptures or ARMs during follow-up; overall mortality for the 5-year study period was 24%. CONCLUSIONS In this series, percutaneous endovascular intervention for type II endoleak with aneurysm sac growth does not appear to alter the rate of aneurysm sac growth, and the majority of patients display persistent/recurrent endoleak. However, diagnostic angiographic evaluation may reveal unexpected type I and III endoleaks and is therefore recommended for all patients with T2EL and sac growth. While coil and glue embolization of aneurysm sac and selected branch vessels does not appear to yield benefit in our series, the diagnosis and subsequent definitive treatment of previously occult type I and III endoleaks may explain the absence of delayed rupture and ARM in our series.

Vagal Denervation and Reinnervation after Ablation of Ganglionated Plexi

OBJECTIVE Surgical ablation of ganglionated plexi has been proposed to increase efficacy of surgery for atrial fibrillation. This experimental canine study examined electrophysiologic attenuation and recovery of atrial vagal effects after ganglionated plexi ablation alone or with standard surgical lesion sets for atrial fibrillation. METHODS Dogs were divided into 3 groups: group 1 (n = 6) had focal ablation of the 4 major epicardial ganglionated plexi fat pads, group 2 (n = 6) had pulmonary vein isolation with ablation, and group 3 (n = 6) had posterior left atrial isolation with ablation. All fat pads were ablated. Sinus and atrioventricular interval changes during bilateral vagosympathetic trunk stimulation were examined before and both immediately and 4 weeks after ablation. Vagally induced effective refractory period changes and mean QRST area changes (index of local innervation) were examined in 5 atrial regions. RESULTS Sinus and atrioventricular interval changes and heart rate variability decreased immediately after ablation, but only sinus interval changes were restored significantly after 4 weeks in all groups. Ablation-modified vagal effects on effective refractory period or QRST area changed heterogeneously in groups 1 and 2. In group 3, regional vagal effects were attenuated extensively postablation in both atria. Posterior left atrial isolation with ablation incrementally denervated the atria. In the long term, vagal stimulation increased QRST area changes relative to control values in all groups. Heart rate variability was also assessed. CONCLUSIONS Ganglionated plexi ablation significantly reduced atrial vagal innervation. Restoration of vagal effects at 4 weeks suggests early atrial reinnervation.

Importance of atrial surface area and refractory period in sustaining atrial fibrillation: Testing the critical mass hypothesis

OBJECTIVE The critical mass hypothesis for atrial fibrillation (AF) was proposed in 1914; however, there have been few studies defining the relationship between atrial surface area and AF. This study evaluated the effect of tissue area and effective refractory period (ERP) on the probability of sustaining AF in an in vivo model. METHODS Domestic pigs (n = 9) underwent median sternotomy. Epicardial activation maps were constructed from bipolar electrograms recorded from form-fitting electrode templates placed on the atria. Baseline ERPs were determined. ERP was lowered with a continuous infusion of acetylcholine (0.005-0.04 mg/Kg/min) until AF could be sustained after burst pacing. The atria were sequentially partitioned using bipolar radiofrequency ablation. ERPs were lowered using acetylcholine until AF could be sustained in each subdivision of atrial tissue. Each subdivision was further divided until AF was no longer inducible. At study completion, the heart was excised and the surface area of each section was measured. RESULTS Over a range of ERPs from 75 to 250 ms, the probability of AF was correlated with increasing tissue area (range, 19.5-105 cm(2)) and decreasing ERP. Logistic regression analysis identified shorter ERP (P < .001) and larger area (P = .006) as factors predictive of an increased probability of sustained AF (area under the curve of the receiver-operator characteristic = 0.878). CONCLUSIONS The probability of sustained AF was significantly associated with increasing tissue area and decreasing ERP. These data may lead to a greater understanding of the mechanism of AF and help to design better interventional procedures.

Differential modulation of right ventricular strain and right atrial mechanics in mild vs. severe pressure overload.

Increased right atrial (RA) and ventricular (RV) chamber volumes are a late maladaptive response to chronic pulmonary hypertension. The purpose of the current investigation was to characterize the early compensatory changes that occur in the right heart during chronic RV pressure overload before the development of chamber dilation. Magnetic resonance imaging with radiofrequency tissue tagging was performed on dogs at baseline and after 10 wk of pulmonary artery banding to yield either mild RV pressure overload (36% rise in RV pressure; n = 5) or severe overload (250% rise in RV pressure; n = 4). The RV free wall was divided into three segments within a midventricular plane, and circumferential myocardial strain was calculated for each segment, the septum, and the left ventricle. Chamber volumes were calculated from stacked MRI images, and RA mechanics were characterized by calculating the RA reservoir, conduit, and pump contribution to RV filling. With mild RV overload, there were no changes in RV strain or RA function. With severe RV overload, RV circumferential strain diminished by 62% anterior (P = 0.04), 42% inferior (P = 0.03), and 50% in the septum (P = 0.02), with no change in the left ventricle (P = 0.12). RV filling became more dependent on RA conduit function, which increased from 30 ± 9 to 43 ± 13% (P = 0.01), than on RA reservoir function, which decreased from 47 ± 6 to 33 ± 4% (P = 0.04), with no change in RA pump function (P = 0.94). RA and RV volumes and RV ejection fraction were unchanged from baseline during either mild (P > 0.10) or severe RV pressure overload (P > 0.53). In response to severe RV pressure overload, RV myocardial strain is segmentally diminished and RV filling becomes more dependent on RA conduit rather than reservoir function. These compensatory mechanisms of the right heart occur early in chronic RV pressure overload before chamber dilation develops.

Differential calcium handling in two canine models of right ventricular pressure overload

BACKGROUND The purpose of this investigation was to characterize differential right atrial (RA) and ventricular (RV) molecular changes in Ca(2+)-handling proteins consequent to RV pressure overload and hypertrophy in two common, yet distinct models of pulmonary hypertension: dehydromonocrotaline (DMCT) toxicity and pulmonary artery (PA) banding. METHODS A total of 18 dogs underwent sternotomy in four groups: (1) DMCT toxicity (n = 5), (2) mild PA banding over 10 wk to match the RV pressure rise with DMCT (n = 5); (3) progressive PA banding to generate severe RV overload (n = 4); and (4) sternotomy only (n = 4). RESULTS In the right ventricle, with DMCT, there was no change in sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) or phospholamban (PLB), but we saw a trend toward down-regulation of phosphorylated PLB at serine-16 (p[Ser-16]PLB) (P = 0.07). Similarly, with mild PA banding, there was no change in SERCA or PLB, but p(Ser-16)PLB was down-regulated by 74% (P < 0.001). With severe PA banding, there was no change in PLB, but SERCA fell by 57% and p(Ser-16)PLB fell by 67% (P < 0.001). In the right atrium, with DMCT, there were no significant changes. With both mild and severe PA banding, p(Ser-16)PLB fell (P < 0.001), but SERCA and PLB did not change. CONCLUSIONS Perturbations in Ca(2+)-handling proteins depend on the degree of RV pressure overload and the model used to mimic the RV effects of pulmonary hypertension. They are similar, but blunted, in the atrium compared with the ventricle.

Factors affecting survival after mitral valve replacement in patients with prosthesis-patient mismatch

BACKGROUND The purpose of this study was to determine the impact of prosthesis-patient mismatch on long-term survival after mitral valve replacement. METHODS From 1992 to 2008, 765 patients underwent bioprosthetic (325; 42%) or mechanical (440; 58%) mitral valve replacement, including 370 (48%) patients older than 65 years of age. Prosthesis-patient mismatch was defined as severe (prosthetic effective orifice area to body surface area ratio <0.9 cm(2)/m(2)), moderate (0.9 to 1.2 cm(2)/m(2)), or absent (>1.2 cm(2)/m(2)). RESULTS Multivariate analysis identified nine risk factors for late death including advanced age, earlier operative year, chronic renal insufficiency, peripheral vascular disease, congestive heart failure, nonrheumatic origin, concomitant coronary artery bypass grafting, lower body surface area, and more severe prosthesis-patient mismatch (lower effective orifice area to body surface area ratio; p < 0.05). For bioprosthetic recipients older than 65 years of age, survival at 5 and 10 years was 30% ± 7% and 0% ± 0% with severe mismatch compared with 43% ± 4% and 21% ± 5% for absent or moderate mismatch, respectively (p = 0.05). For mechanical recipients younger than 65 years of age, survival at 5 and 10 years was 77% ± 4% and 62% ± 6% with moderate or severe mismatch compared with 82% ± 3% and 66% ± 4%, respectively, without mismatch (p = 0.08). CONCLUSIONS Severe mismatch adversely affected long-term survival for older patients receiving bioprosthetic valves. With mechanical valves, there was a trend toward impaired survival when mismatch was moderate or severe in younger patients. Thus, selection of an appropriate mitral prosthesis warrants careful consideration of age and valve type.

Chronic performance of a novel radiofrequency ablation device on the beating heart: Limitations of conduction delay to assess transmurality

OBJECTIVE The creation of consistently transmural lesions with epicardial ablation on the beating heart has represented a significant challenge for current technology. This study examined the chronic performance of the AtriCure Coolrail device (AtriCure Inc, West Chester, Ohio), an internally cooled, bipolar radiofrequency ablation device designed for off-pump epicardial ablation. The study also examined the reliability of using acute intraoperative conduction delay to evaluate lesion integrity. METHODS Seven swine underwent median sternotomy. The right atrial appendage and inferior vena cava were isolated with a bipolar radiofrequency clamp. Linear ablation lines were created between these structures with the AtriCure Coolrail. Paced activation maps were recorded with epicardial patch electrodes acutely before and after ablation and after keeping the animals alive for 4 weeks. The conduction time across the linear ablation was calculated from these maps. The lesions were histologically evaluated with trichrome staining. RESULTS Only 76% of cross-sections of Coolrail lesions were transmural, and only 1 of 12 ablation lines was transmural in every cross-section examined. Mapping data were available in 5 of the animals. Significant conduction delay was present after the creation of each line of ablation acutely; however, after 4 weeks, conduction time returned to preablation values, demonstrating lack of transmurality. CONCLUSIONS The AtriCure Coolrail failed to reliably create transmural lesions. Although the Coolrail was able to create acute conduction delay, its failure to transmurally ablate the atrial myocardium left gaps along the length of the lesion, which resulted in neither chronic conduction block nor delay across any line of ablation.

Surgical management of abdominal aortic aneurysms: a lost art?

Endovascular repair of abdominal aneurysms has become the dominant treatment modality for infrarenal aneurysms. Initial reports showed a constant number of open repairs although there was a shift toward complicated juxtra-renal aneurysms. In the past several years, more aggressive endoluminal approaches and the introduction of fenestrated grafts have appeared to dilute the open aneurysm operating experience. Coupled with work hours restrictions and shorter training paradigms, opportunities for training residents in open repair of abdominal aneurysms are decreasing. We envision that future treatment of complicated aortic aneurysms will likely entail advanced fellowship training in open repair and referral of complicated abdominal aneurysms to tertiary care centers.

Proteomic Profiling of Early Chronic Pulmonary Hypertension: Evidence for Both Adaptive and Maladaptive Pathology.

Background The molecular mechanisms governing right atrial (RA) and ventricular (RV) hypertrophy and failure in chronic pulmonary hypertension (CPH) remain unclear. The purpose of this investigation was to characterize RA and RV protein changes in CPH and determine their adaptive versus maladaptive role on hypertrophic development. Methods Nine dogs underwent sternotomy and RA injection with 3 mg/kg dehydromonocrotaline (DMCT) to induce CPH (n=5) or sternotomy without DMCT (n=4). At 8-10 weeks, RA and RV proteomic analyses were completed after trypsinization of cut 2-D gel electrophoresis spots and peptide sequencing using mass spectrometry. Results In the RV, 13 protein spots were significantly altered with DMCT compared to Sham. Downregulated RV proteins included contractile elements: troponin T and C (-1.6 fold change), myosin regulatory light chain 2 (-1.9), cellular energetics modifier: fatty-acid binding protein (-1.5), and (3) ROS scavenger: superoxide dismutase 1 (-1.7). Conversely, beta-myosin heavy chain was upregulated (+1.7). In the RA, 22 proteins spots were altered including the following downregulated proteins contractile elements: tropomyosin 1 alpha chain (-1.9), cellular energetic proteins: ATP synthase (-1.5), fatty-acid binding protein (-2.5), and (3) polyubiquitin (-3.5). Crystallin alpha B (hypertrophy inhibitor) was upregulated in both the RV (+2.2) and RA (+2.6). Conclusions In early stage hypertrophy there is adaptive upregulation of major RA and RV contractile substituents and attenuation of the hypertrophic response. However, there are multiple indices of maladaptive pathology including considerable cellular stress associated with aberrancy of actin machinery activity, decreased efficiency of energy utilization, and potentially decreased protein quality control.

Popliteal Artery Aneurysm Repair With Minimally Invasive Endoscopic Vein Harvest Yields Outstanding Wound Healing Outcomes With Fast-Tracked Hospitalization

Groin Assessment Scale and a prediction model developed at Duke University in our population of patients. Methods: The medical records of all patients who underwent groin exposure for a vascular procedure between January 1, 2017, and October 31, 2017, at our institution were reviewed after Institutional Review Board approval. Patients’ demographics, perioperative variables, and outcomes including groin SSI were evaluated. Risk scores were calculated for each patient to determine preoperative SSI risk according to the Penn and Duke models. SSI occurrence was used to determine the predictive power of each scoring method by receiver operating characteristic (ROC) analysis. Results: A total of 100 surgical procedures met our inclusion criteria, with an overall groin incision SSI prevalence of 14%. One-third of patients in our cohort were obese (body mass index >30 kg/m), and the majority of cases (64%) were elective (Table). This was a representative sample of bypass procedures using both prosthetic (16%) and vein graft (19%) as well as open cutdown procedures for thrombectomy (38%). The ROC coefficients of the Penn and Duke scores in our population of patients were 0.61 and 0.62, respectively (Fig). The associated positive and negative predictive values of each score for development of groin SSI were poor. Conclusions: In our population of vascular surgery patients, the Penn Groin Assessment Scale and Duke models were poor predictors of groin SSI, as indicated by an ROC coefficient that is close to 0.5. One limitation of our study is small sample size. A more extensive retrospective study to build a risk prediction model for our population will be undertaken. Although validation of these models in a larger sample is warranted, this may indicate the need for individual medical centers to tailor risk assessment models specific to their population of patients.