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Michael K Pasque

Publications and source records attributed to Michael K Pasque.

36 records · Page 2Linked to original sources
PubMed2004

Noninvasive, quantitative assessment of left ventricular function in ischemic cardiomyopathy.

BACKGROUND: Coronary artery disease characteristically impacts left ventricular (LV) function on a regional basis, although ultimately global function may be affected as well. Echocardiography is commonly clinically used for the assessment of regional function; however, it is only semiquantitative and in its current iteration is only two-dimensional in nature. Magnetic resonance imaging (MRI) with tissue tagging offers the possibility for noninvasive, three-dimensional (3D) assessment of transmural and segmental left ventricular strain and, thereby, function. Accordingly, we have explored methodologies to accurately and quantitatively characterize regional systolic function in three dimensions in patients with ischemic heart disease using MRI. MATERIALS AND METHODS: MRI radiofrequency tissue tagging was performed at rest and during dobutamine administration (10 mg/kg/min) on 10 normal volunteers (age: 26 +/- 6) and 8 patients with severe ischemic cardiomyopathy (age: 60 +/- 5, EF 26 +/- 11%). Three-dimensional global and regional systolic strain calculations were made based on 3D myocardial point displacements and compared with conventional measures. RESULTS: Global left ventricular strains were significantly decreased in ischemic patients at rest (0.14 +/- 0.04 versus 0.25 +/- 0.02, P < 0.001) and with dobutamine (0.14 +/- 0.03 versus 0.29 +/- 0.03, P < 0.001). In the regional analysis (216 LV wall segments) this methodology accurately differentiated normal from abnormally contracting regions. CONCLUSIONS: Noninvasive dobutamine MRI tissue tagging with calculation of 3D regional strains has significant promise as a clinical tool which is capable of the identification, quantification, and display of regionally varying ventricular function.

Aged↗
PubMed2004

Ventricular function after coronary artery bypass grafting: evaluation by magnetic resonance imaging and myocardial strain analysis.

OBJECTIVE: Magnetic resonance imaging with radiofrequency tissue tagging permits quantitative assessment of regional systolic myocardial strain. We sought to investigate the utility of this imaging modality to quantitatively determine preoperative impairment and postoperative improvement in ventricular function in patients with ischemic heart disease. METHODS: Magnetic resonance imaging with radiofrequency tissue tagging was performed on 6 patients (average age 60.2 +/- 13.7 years) with coronary artery disease and 32 control subjects with no known heart disease. Patients with coronary artery disease underwent imaging before and 3 months after coronary artery bypass grafting. The ventricle was divided into 6 segments within a midventricular plane. Regional 2-dimensional left ventricular circumferential strain was calculated from tagged magnetic resonance images throughout systole. Circumferential strain results were compared in patients before and after and 3 months after coronary artery bypass grafting and also in control subjects. RESULTS: Before the operation circumferential strain identified 100% (10/10) of all regional wall motion abnormalities seen by preoperative ventriculography. Postoperatively, improvements were demonstrated in 56% (20/36) of the regions, and these improvements agreed with viability testing by single-photon emission computed tomography when available. Additionally, preoperative global circumferential strain for the ischemic group was significantly depressed relative to that in control subjects (0.11 +/- 0.05 vs 0.20 +/- 0.03, P <.001). Global circumferential strain correlated with ejection fraction by ventriculography (r = 0.84, P <.01) and improved after coronary artery bypass grafting (0.14 +/- 0.05 vs 0.11 +/- 0.05, P <.01). CONCLUSIONS: Magnetic resonance imaging with radiofrequency tissue tagging permitted circumferential strain calculation. This technology quantitatively demonstrated improvements in left ventricular wall motion after coronary artery bypass grafting for both individual regions and the entire ventricle. This noninvasive method may prove useful in preoperative evaluation and postoperative serial assessment of left ventricular wall motion.

Adult↗
PubMed2004

Survival of patients removed from the heart transplant waiting list.

OBJECTIVE: End-stage heart failure has been associated with high mortality in the absence of transplantation. We evaluated the outcome of patients receiving optimal medical therapy who were removed from the cardiac transplant waiting list to determine survival and predictors of mortality. METHODS: We performed a retrospective review of 27 patients removed from the cardiac transplant waiting list from 1999 to 2001 at our institution. RESULTS: Mean age was 53 +/- 11 years; 16 of the patients were male. Status was IB in 3 cases and II in 24. Median time on the list was 32 months, and median follow-up was 2.9 years. Patients were removed from the transplant list because of either clinical improvement (group A, n = 18) or deterioration (group B, n = 9). In group A, 13 patients had improved functional status and 10 were in New York Heart Association class 1 or 2; 16 had improved echocardiographic left ventricular function. Survivals at 3 years were 100% in group A and 44% in group B (P <.01). CONCLUSION: Patients with end-stage heart failure who have clinical response to medical therapy have excellent 3-year survival. These data suggest the necessity of close evaluation of patients waiting for transplantation, with a low threshold for inactivation if persistent clinical improvement is observed.

Cause of Death↗
PubMed2003

Nesiritide (BNP) in the management of postoperative cardiac patients.

Recombinant human B-type natriuretic peptide (BNP) is a promising new agent in the management of heart failure. The pharmacologic properties of BNP make it desirable to use in a subset of patients after cardiac surgical operations. Among these therapeutic potentials is the effect on markedly reducing pulmonary vascular resistance and central venous pressure with mild systemic vasodilatation. In addition, BNP directly effects the kidneys to promote natriuresis. We believe this agent to be useful in the treatment of the postcardiac surgery patients with left ventricular dysfunction and mild to moderate renal insufficiency. This report summarizes our experience in 2 patients.

Aged↗
PubMed2003

Severe aortic insufficiency and normal systolic function: determining regional left ventricular wall stress by finite-element analysis.

BACKGROUND: Because severe aortic insufficiency in the setting of preserved left ventricular function is often associated with a long asymptomatic period and unpredictable course on medical therapy, sensitive indices of left ventricular systolic performance are necessary for the optimal direction of therapeutic intervention. Because myocardial wall stress is closely related to both pathologic cardiac remodeling and ultimately to left ventricular decompensation, an accurate description of regional wall stress distribution may improve our ability to clinically manage these patients appropriately. The objectives of this study were (1) to define sensitive, noninvasive indices of left ventricular systolic performance to assist the clinician in the serial evaluation and early detection of increased left ventricular wall stress and, therefore, inadequate left ventricular remodeling and subsequent myocardial decompensation of patients with aortic insufficiency, and (2) to quantify differences in instantaneous global and regional end-systolic wall stress between normal subjects and patients. METHODS: Magnetic resonance imaging was performed on 23 normal volunteers and 19 patients with aortic insufficiency and normal systolic function (ejection fraction, 57% +/- 6%). Finite-element analysis was used to estimate global and regional end-systolic stress. RESULTS: End-systolic stress was significantly higher in the patient group globally (154,700 +/- 31,711 versus 96,781 +/- 23,185 dyne/cm(2); p < 0.001) and regionally (p < 0.001 in all segments) despite normal systolic function and similar end-systolic pressures. CONCLUSIONS: End-systolic stress as determined by magnetic resonance imaging and finite-element analysis may have considerable potential as a noninvasive, clinically applicable index of regional left ventricular function that may help in the serial evaluation, optimal management, and early identification of left ventricular decompensation in patients with aortic insufficiency.

Adult↗
PubMed2003

Radial artery patency: are aortocoronary conduits superior to composite grafting?

BACKGROUND: The radial artery (RA) can be used as either an aortocoronary (RA-Ao) or composite graft (T graft). Optimum use for the RA has yet to be established. We compared RA patency with these two techniques. METHODS: Between October 1993 and June 2001, 1505 patients underwent coronary artery bypass grafting using the RA as either a composite (n = 1022) or RA-Ao graft (n = 483). Angiograms performed on 203 (13.5%) patients with signs or symptoms of ischemia at an average of 26.1 +/- 18.5 months postoperatively were reviewed. RESULTS: Patients with RA-Ao grafts had a greater incidence of postoperative angiography versus patients with composite grafts (19% versus 11%; p < 0.01). Patients receiving T grafts had a greater number of anastomoses per patient (4.1 +/- 0.6 versus 3.0 +/- 1.0; p < 0.01) and a higher incidence of total arterial revascularization (100% versus 41%; p < 0.01). Regardless of grafting strategy, patency was significantly worse for targets of the right coronary artery (58% T graft; 67% RA-Ao; p < 0.01 for both) and for targets with less than or equal to 70% stenosis (59% T graft; 57% RA-Ao; p < 0.01 for both). The site of proximal anastomosis failed to effect RA patency (relative risk, 1.2; 95% confidence interval, 0.7 to 1.8; p = 0.50). CONCLUSIONS: The site of the proximal anastomosis does not appear to influence patency. Both RA-Ao and composite conduits are sensitive to target location and stenosis. Advantages of composite grafting include greater conduit length and minimizing aortic manipulation at the expense of increased complexity and the potential for hypoperfusion. These factors should be considered when choosing an RA grafting strategy.

Aged↗
PubMed2002

Altered left ventricular geometry changes the border zone temporal distribution of stress in an experimental model of left ventricular aneurysm: a finite element model study.

BACKGROUND: Left ventricular aneurysm (LVA) is a significant complication of myocardial infarction that may lead to global left ventricular (LV) dysfunction. However, the exact mechanism underlying the abnormal function has not been elucidated. In this study we tested the hypothesis that changes in LV geometry cause both an increase in wall stress and a change in the temporal distribution of stress in the LVA border zone (BZ) during systole. METHODS: Transmural anteroapical infarcts were created in adult Dorsett sheep (n=8) and were allowed to mature into LVAs for 10 weeks. Animals were imaged subsequently using MRI with simultaneous recording of intraventricular pressures. Cardiac models were constructed from the MRI images at end-diastole, isovolumic systole, peak-systole and end-systole. Two short-axis slices, 1 basal and 1 apical were analyzed. The apical slice included the septal and anterior component of the aneurysm as well as the corresponding BZs and normal myocardium. Regional wall stresses were calculated using finite element analysis and compared with stresses in corresponding regions from normal control sheep (n=7). RESULTS: In the LVA group, stress was significantly increased in the BZ at the end-diastolic, isovolumic, peak-systolic, and end-systolic instants (P<0.001 for all). In addition the temporal distribution of stress was significantly altered with maximum stress occurring at peak instead of isovolumic systole. CONCLUSIONS: Geometric changes in the LVA hearts increased wall stress and altered its temporal distribution in the BZ region. Correlation of this finding with the corresponding regional blood flow, oxygen consumption, and mechanical systolic performance may help elucidate the mechanism underlying the observed global LV dysfunction.

Animals↗
PubMed2002

Lung transplantation for pulmonary vascular disease.

BACKGROUND: Pulmonary hypertension (PHT) is a lethal condition resulting in markedly diminished life expectancy. Continuous prostaglandin I2 infusion has made an important contribution to symptom management, but it is not a panacea. Lung or heart-lung transplantation remains an important treatment option for end-stage PHT patients unresponsive to prostaglandin I2. This study reviews the outcomes after transplantation for PHT in our program. METHODS: A retrospective chart review was performed for 100 consecutive patients with either primary PHT (48%) or secondary PHT (52%) transplants since 1989. Living recipients were contacted to confirm health and functional status. RESULTS: Fifty-five adult and 45 pediatric patients underwent 51 bilateral lung transplants, 39 single lung transplants, and 10 heart-lung transplants. Mean age was 23.7 years (range, 1.2 months to 54.8 years) and mean pre-transplant New York Heart Association class was 3.2. Pre-transplant hemodynamics revealed a mean right atrial pressure of 9.6+/-5.4 mm Hg and mean pulmonary artery pressure of 64+/-14.4 mm Hg. Hospital mortality was 17% with early death predominantly because of graft failure and infection. With an average follow-up of 5.0 years, 1- and 5-year actuarial survival was 75% and 57%, respectively. Mean pulmonary artery pressure on follow-up catheterization was 22+/-6.0 mm Hg, and mean follow-up New York Heart Association class was 1.3 (p < 0.001 for both compared with pre-transplant). Diagnosis and type of transplant did not confer a significant difference in survival between groups. CONCLUSIONS: Whereas lung or heart-lung transplant for PHT is associated with higher early mortality than other pulmonary disease entities, it provides similar long-term outcomes with dramatic improvement in both quality of life and physiologic aspects.

Adolescent↗
PubMed2002

Surgical management of Novacor drive-line exit site infections.

Implantable left ventricular assist device (LVAD) drive-line exit site infection, an expected consequence of currently available device use, continues to be a significant limiting factor in long-term support. We theorize that the mechanism behind the establishment of the most chronic exit site infections involves a shearing torsion injury that disrupts the tissue adherence interface with the drive-line. The resulting neo-epithelialized drainage tract prevents permanent clearance of the infection with antibiotics alone. The proposed treatment strategy of established infections involves aggressive surgical excision of the involved exit site.

Anti-Bacterial Agents↗
PubMedDate not supplied

Hypertensive left ventricular hypertrophy is associated with abnormal myocardial fatty acid metabolism and myocardial efficiency.

BACKGROUND: Hypertension-induced left ventricular hypertrophy (LVH) is associated with an increased risk of cardiovascular morbidity and death by mechanisms not well characterized. METHODS AND RESULTS: Myocardial fatty acid (FA) metabolism and left ventricular (LV) mass were evaluated in 13 patients with hypertensive LVH with normal LV ejection fraction and 42 normal control subjects (primary cohort). Contractile performance was also evaluated in 5 hypertensive LVH patients and 5 matched normal control subjects (magnetic resonance [MR] substudy). Myocardial FA utilization (MFAU) and myocardial FA oxidation (MFAO) were assessed by positron emission tomography by use of 1-carbon-11 palmitate. Myocardial contractile function (strain and stress) was determined by cardiac MR imaging with tissue tagging and calibrated arterial pressure traces; myocardial external minute work and efficiency were derived. In the primary cohort decreased MFAO was predictive of increased LV mass (model r(2) = 0.61, P = .03). In the MR substudy decreased MFAO (corrected for myocardial oxygen consumption [MVO(2)]) in the hypertensive LVH group compared with the normal group (MFAU/MVO(2), 26 +/- 5 vs 37 +/- 8; MFAO/MVO(2), 24 +/- 6 vs 35 +/- 7; both P = .03) was paralleled by decreased myocardial external minute work (0.13 +/- 0.03 J x g(-1) x min(-1) vs 0.17 +/- 0.04 J x g(-1) x min(-1), P = .07) and decreased myocardial efficiency (5.2% +/- 1.4% vs 7.1% +/- 1.0%, P = .03). CONCLUSIONS: Abnormalities in myocardial FA metabolism are apparent in hypertensive LVH, and these abnormalities may be responsible, at least in part, for a reduction in myocardial efficiency.

Aged↗
PubMedDate not supplied

Does functional mitral regurgitation improve with isolated aortic valve replacement?

BACKGROUND: The surgical treatment of mitral valve regurgitation (MR) at the time of aortic valve replacement (AVR) remains controversial. The purpose of this study was to evaluate the change in severity of MR following isolated AVR, and to determine survival benefit. METHODS: Between 1991 and 2001, 250 patients underwent isolated AVR; 196 patients had concomitant functional MR. Follow-up transthoracic echocardiography (TTE) was available on 107 patients, with a median of 818 +/- 752 days. Aortic valve was stenotic in 77 and regurgitant in 30 patients. RESULTS: Mean age was 67 +/- 15 years and 57 (53%) were male. Preoperative MR was trivial (1+) in 27 (25%), mild (2+) in 44 (41%), moderate (3+) in 29 (27%), and severe (4+) in 7 (7%). At follow-up TTE, MR improved by 1 or 2 grades in 48 patients (45%). Of patients with preoperative 2+ MR, 19 (43%) improved, 16 (36%) remained unchanged, and 9 (21%) worsened. Although some patients with preoperative 3+ MR exhibited improvement, 11 (38%) remained with moderate-to-severe MR. Of those with a preoperative MR of 4+, 3 (71%) improved, and 4 remained with 3-4+ MR. For patients with preoperative 1 to 2+ MR, survival at 3 years was 98% compared to 78% for those with 3 to 4+ MR (p = 0.038). CONCLUSION: Functional MR does not always improve after isolated AVR. Survival is lower for patients with preoperative 3 to 4+ MR. Moderate-to-severe MR should be repaired at the time of aortic valve surgery.

Aged↗
PubMedDate not supplied

Contemporary results of total aortic arch replacement.

BACKGROUND AND AIM: Aneurysmal dilatation of the aortic arch is uncommon, and the complex anatomy involved imposes unique technical challenges. The results of surgical intervention reported from large centers are improving; however, the degree to which these results are reproducible by other surgeons is less clear. We therefore reviewed our recent experience with total aortic arch replacement. METHODS: Between July 1, 1997 and July 1, 2001 19 patients underwent complete aortic arch replacement, with or without concomitant procedures. We retrospectively reviewed perioperative results retrieved from the computerized database and clinical records. RESULTS: The mean age of the study population was 68 +/- 8.3 years (range 52 to 82), with women predominating (11 women, 8 men). All patients had hypertension. Patient history indicated active or past tobacco abuse in 16 patients (80%); cerebrovascular disease in 3, and peripheral vascular disease in 7 patients. Associated procedures included an elephant trunk in 12 (63%), replacement of the upper descending thoracic aorta in 5 (26%), concomitant coronary artery bypass in 5 (26%), and aortic root replacement in 3 (16%). One patient underwent replacement of the entire aorta from sinotubular ridge to iliac bifurcation in a single procedure. Brachiocephalic reconstruction with a "Y-graft" permitting early antegrade cerebral perfusion was performed in 12 patients. Retrograde cerebral perfusion was performed in ten patients (53%). Perioperatively, death occurred in two patients (11%) and stroke in two (11%). CONCLUSIONS: With cautious application, techniques developed in high-volume centers can also achieve satisfactory results when used at centers with a more modest case volume.

Aged↗
PubMedDate not supplied

Operative strategies to reduce complications in Novacor left ventricular assist device placement.

BACKGROUND: The original Novacor left ventricular assist device (LVAD) implant procedure has been extensively modified since its introduction. Our goal is to describe, in a concise and comprehensive fashion, the status of this evolution as we currently employ it at our institution. We will also investigate the possible impact of the adoption of this current methodology on the incidence of perioperative hemorrhage at our institution. METHODS: The number of units of blood transfused on the day of implant surgery and the incidence of reexploration for postoperative hemorrhage were compared between the early group of consecutive patients implanted before adoption of the described implant strategy (n = 10) and the late group of consecutive patients implanted after uniform implementation of this methodology (n = 20). RESULTS: Operative and immediate postoperative hemorrhage, as demonstrated by the number of blood transfusions on the day of implant surgery, was significantly reduced in the group of consecutive patients implanted after adoption of these techniques when compared to the group of patients implanted prior to technical modification. CONCLUSION: The currently utilized Novacor LVAD implant procedure is described in detail. The amount of blood transfused on the implant day has significantly decreased since the uniform adoption of the current procedure, suggesting that the degree of perioperative hemorrhage has been favorably affected. Although implantation complications can be surgeon, device, institution and patient-specific, the strategies employed in the current implant procedure may be helpful at other heart failure centers.

Adolescent↗
PubMedDate not supplied

Morbidity and mortality of cardiac surgery following renal transplantation.

BACKGROUND: With improved survival following renal transplantation, the number of patients undergoing cardiac surgery has increased. The purpose of this study was to review the morbidity, mortality, and allograft function in renal transplant patients undergoing major cardiac surgery. METHODS: Retrospective database review of consecutive renal transplant patients undergoing cardiac surgery from 1987 to 2002. Patients requiring dialysis (D) before cardiac surgery versus those with stable renal transplants (ND) were compared. RESULTS: Cardiac surgery was performed in 46 patients during the study period. Twenty patients (42%) required dialysis (D) before surgery while 26 (58%) had stable allograft function (ND). Among patients who had stable allograft function prior to surgery, there was no allograft loss. In the ND group, preoperative and discharge creatinine levels were 2.17 +/- 1.0 and 2.4 +/- 1.5 mg/dL, respectively. All operative deaths occurred in the dialysis dependent group. The 30-day and 3-year survival, respectively was 80% and 20% in the D group compared to 100% and 69% amongst the ND group (p </= 0.01). Infectious complications consisted of pneumonia and sepsis each in 8.5% and of deep sternal wound infection in 4.3% of the entire group. CONCLUSIONS: (1) Morbidity and mortality of cardiac surgery in renal transplant patients with stable allograft function is low and stable allograft function can be maintained without allograft loss. (2) Mortality following cardiac surgery is significantly higher among renal transplant patients who become dialysis dependent and intermediate-term survival is poor.

Cardiac Surgical Procedures↗
PubMedDate not supplied

Aortic valve replacement for aortic insufficiency: valve type as a determinant of systolic strain recovery.

BACKGROUND AND AIM: Left ventricular (LV) 3D systolic strain decreases in absolute value postoperatively and does not recover in patients who undergo aortic valve replacement (AVR) for chronic aortic insufficiency (AI). We investigated whether choice of valve prosthesis (mechanical [St. Jude], bioprosthetic [bovine pericardial], Ross procedure) had a significant impact on strain recovery in this surgical population. METHODS: MRI with tissue-tagging was performed on 14 patients with chronic AI both before and 28 +/- 13 months after AVR. Average values of LV systolic strain and end-systolic stress (ESS) were computed from MRI data for the LV. Three types of prosthetic valve were examined (Ross procedure n = 4, bovine pericardial n = 5, and St. Jude n = 5). RESULTS: Overall, systolic strain, ESS, LV volumes, ejection fraction, and LV mass all changed significantly following AVR. Comparisons between individual valve types revealed no differences in any of these measurements. Patients who received a mechanical valve had a greater decrease in the absolute value of systolic strain following surgery compared to patients from the nonmechanical group (Ross procedure and bioprosthetic valve). Comparisons between the Ross group and the prosthetic group (St. Jude and bioprosthetic) produced no significant differences in strain, ESS, LV volume, and mass. CONCLUSIONS: These early results suggest that valve prosthetic type may be a factor in efforts to improve strain recovery after AVR for AI, although further investigation is warranted. MRI with tissue-tagging may be a useful tool for comparing the impact of prosthetic valve choice on incompletely recovered systolic strain following AVR for chronic AI.

Adult↗