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Biomedical subjects

G Michael Deeb

Publications and source records attributed to G Michael Deeb.

16 recordsLinked to original sources
PubMed2006

Resection of the descending thoracic aorta: outcomes after use of hypothermic circulatory arrest.

BACKGROUND: Use of hypothermic circulatory arrest (HCA) for operations on the descending thoracic aorta is controversial. While deep hypothermia may provide better end-organ and spinal cord function, prolonged cardiopulmonary bypass and circulatory arrest may increase morbidity. This study assessed outcomes after use of HCA for descending thoracic aortic resection in a large cohort of consecutive patients. METHODS: Hypothermic circulatory arrest was utilized if arch or extensive descending thoracic aortic resection was required, or if aortic pathology precluded cross-clamping. One hundred thirty-two patients (mean age, 61.3 years) were identified. Diagnosis included fusiform (41.2%) or saccular aneurysm (10.7%) and acute (4.6%) or chronic (38.9%) dissection. Twenty-one patients presented with rupture. Arch resection (distal arch 100, total arch 11) was required in 111 patients (84.1%). The extent of descending thoracic aortic resection (required in 94%) included proximal third in 41 patients, proximal two-thirds in 6, and complete thoracic aorta in 77. The proximal anastomosis was performed with total body HCA while the distal anastomosis was constructed with lower body HCA only (duration upper body HCA 33.7 +/- 8.0 minutes; total duration lower body HCA 71.3 +/- 24.2 minutes). RESULTS: Thirty-day mortality was 6.0%. Neurologic events included stroke (6.8%) and permanent lower extremity paralysis-paresis (4.5%). Temporary dialysis was needed in 7 (5.3%), though only 2 patients required permanent dialysis (1.9%). Independent predictors of a composite endpoint of death, stroke, permanent paralysis, or dialysis included duration of lower body HCA (p = 0.03) and major postoperative infection (p = 0.003). CONCLUSIONS: Adjunctive use of deep hypothermic circulatory arrest for descending thoracic aortic resection affords excellent preservation of end-organ and spinal cord function with acceptable rates of mortality and significant morbidity.

Acute Kidney Injury↗
PubMed2006

A biologic basis for asymmetric growth in descending thoracic aortic aneurysms: a role for matrix metalloproteinase 9 and 2.

OBJECTIVE: This study was undertaken to define matrix metalloproteinase (MMP) expression in the anterior and posterior wall of descending thoracic aortic aneurysms (TAAs) and correlate it with specific computed tomography (CT) image sites within the descending thoracic aorta. METHODS: Serial CT images of patients with TAAs were compared with age- and gender-matched normal descending thoracic aortas at levels T4-T12. The mean circumference of the TAAs was 153 mm (n = 12) and 148 mm (n = 11) at T8 and T10, respectively, compared with 75 mm (n = 12) and 75 mm (n = 10) in controls (P < .001). Aortic tissue was collected from a separate set of eight patients undergoing descending TAA resection (processed < or =12 hours of excision) and six cadavers (processed < or =24 hours of death). Tissue collected between the intercostals arteries was defined as posterior wall, and directly opposite was the anterior wall. MMP-9 and MMP-2 messenger RNA (mRNA) extracted from aortic tissue was analyzed by quantitative real time polymerase chain reaction (PCR) and normalized to beta-actin. Immunohistochemistry was performed for MMP-9 and MMP-2. CT aortic measurements and MMP expression were compared by t tests and analysis of variance, respectively. RESULTS: The ratio of arc distance between the intercostals on the posterior wall to total aortic circumference was 0.14 in healthy controls compared with 0.08 in TAAs at vertebral level T8 (P = .001). At T10, the ratio was 0.15 in healthy controls compared with 0.11 in TAAs (P = .001). MMP-9 expression in TAAs was 4.3-fold higher in the anterior wall compared with the posterior wall (P = .03). Conversely, MMP-2 expression in TAAs was 3.2-fold higher in the posterior wall compared with the anterior wall (P = .008). MMP expression was not detected in control cadaver aortas. CONCLUSION: Anterior walls of expanding TAAs grow at a greater rate than the posterior wall, as determined from the lower ratio of intercostal arc distance to total circumference in TAAs. Differential MMP expression appears to be a biologic marker for asymmetric growth in the TAA wall. CLINICAL RELEVANCE: The pathogenesis of thoracic aortic aneurysms (TAAs) is poorly understood. Multiple lines of evidence suggest that matrix metalloproteinases (MMPs), a family of enzymes, are important in aneurysm development. Earlier experiments documented a regional variation of MMP-9 in stimulated rodent aortas, with production greater in the abdominal aorta compared with the thoracic aorta. The present study extends that observation and documents asymmetric aneurysm development in the TAA wall, with increased anterior wall growth in correlation to increased MMP-9 production. An improved understanding of the mechanisms by which MMP production is regulated is critical.

Aortic Aneurysm, Thoracic↗
PubMed2005

Anterior leaflet repair with patch augmentation for mitral regurgitation.

BACKGROUND: Anterior leaflet repair continues to pose significant operative challenges, particularly in patients with retracted or "short" anterior leaflets, due to rheumatic or radiation induced mitral valve disease. This often results in abandonment of repair in favor of mitral valve replacement, requiring anticoagulation and altering left ventricular (LV) function and geometry. This study examines our experience of anterior leaflet repair with patch augmentation. METHODS: Forty-two patients underwent mitral valve repair for a shortened anterior leaflet from 1994 to 2003. Twenty-two patients with a mean age of 53 +/- 6 years had radiation valvulitis (XR) whereas 20 patients, age 28 +/- 7 years had rheumatic heart disease (RHD). Those patients with XR had a mean New York Heart Association (NYHA) class of 3.2 +/- 0.4 and an angina score of 2.1 +/- 0.6 compared with a NYHA class 3.8 +/- 0.2 and no angina in RHD patients. All patients presented with severe MR. Anterior leaflet augmentation with a gluteraldehyde-treated, autologous pericardial patch and complete annuloplasty ring was used in all patients. Additionally, extensive subvalvar debridement was performed in RHD patients. Twelve XR patients underwent concomitant CABG with a mean of 2.4 +/- 0.8 grafts/patient. Additional surgical procedures included tricuspid valve repair, anterior septal defect, and aortic valve replacement. Mean follow-up was 39 +/- 10 months for XR patients and 12 +/- 25 months for RHD patients. RESULTS: There were two late deaths in XR patients from underlying malignancies and no deaths in RHD patients. Two RHD patients required reoperation for recurrent mitral regurgitation at 3 and 20 months. All patients demonstrated clinical improvements (NYHA I-II) following repair. No mitral stenosis was induced. CONCLUSIONS: Despite anterior leaflet shortening from XR or rheumatic alterations, opportunity still exists for gratifying mitral valve repair. By utilizing anterior leaflet patch augmentation, concomitantly with ring annuloplasty, anticoagulation is avoided, LV geometry is preserved, and follow-up reveals excellent functional improvement.

Adult↗
PubMed2005

Endograft repair of partially anomalous pulmonary venous connection with dual drainage.

A 73-year-old woman with dyspnea and fatigue was found to have a partially anomalous pulmonary venous connection with communication between the right upper lobe pulmonary vein and the superior vena cava, as well as a normal pulmonary vein confluence with the left atrium. She was successfully treated with an endograft implanted in the superior vena cava, covering the defect. The unique dual drainage of the pulmonary vein allowed percutaneous treatment of a condition that ordinarily requires complex caval and intracardiac reconstruction. Except for several episodes of arrhythmias, she has been doing well, with exercise tolerance improving from New York Heart Association class III at baseline to class I after treatment. Follow-up imaging and clinical findings at 36 months showed no migration of the stents and significant improvement of quality of life.

Aged↗
PubMed2004

Atrial reduction plasty Cox maze procedure: extended indications for atrial fibrillation surgery.

BACKGROUND: The Cox maze procedure yields good results for atrial fibrillation (AF). However, patients with predictors of failure-chronic long-standing AF, low amplitude fibrillatory waves, and large left atriums-are generally thought not to benefit from a maze procedure. We report an aggressive approach for these patients, utilizing biatrial reduction plasty concomitantly with the Cox maze procedure for AF. METHODS: A complete Cox maze procedure utilizing supplemental RF ablation was performed in 36 patients. All underwent resection of both atrial appendages and biatrial reduction plasty encompassing resection of the left atrial posterior wall from left to right pulmonary veins and from inferior pulmonary veins to the mitral annulus, as well as removal of the right atrial lateral wall. Mitral or tricuspid valve repair, or both, was performed on 32 patients. RESULTS: These patients had a mean AF duration of 45 +/- 89 months. Their preoperative left atria measured 66 +/- 16 mm, with mean AF waves of 0.74 +/- 0.3 mm. Mean preoperative New York Heart Association class was 2.7 +/- 0.7 and left ventricular ejection fraction was 48 +/- 9. Cross clamp and bypass times were 91 +/- 35 minutes and 124 +/- 33 minutes, respectively. The average posterior left atrial tissue resected was 5.4 x 2.1 cm, and mean resected atrial weight was 10.3 +/- 2 g. There were no deaths and length of stay was 5.5 +/- 2 days. At a follow-up time of 19 +/- 16 months, 32 of the 36 patients were in normal sinus rhythm and New York Heart Association class I. CONCLUSIONS: Aggressive biatrial reduction plasty Cox maze procedure was effective in 89% of these "low success" AF patients. This simple procedure can extend utilization of the Cox maze procedure to more patients with chronic AF.

Aged↗
PubMed2004

Intraoperative transesophageal echocardiography after aortic valve replacement does not predict subsequent transvalvular gradients.

BACKGROUND AND AIM OF THE STUDY: Intraoperative transesophageal echocardiography (TEE) can be used to assess gradients after aortic valve replacement (AVR). However, altered cardiac output after weaning from cardiopulmonary bypass, dynamic changes in valve function early after surgery, and limitations in transducer alignment may compromise the ability to predict valve hemodynamics on follow up. The study aim was to compare gradients on intraoperative TEE immediately after AVR with gradients on transthoracic echocardiography (TTE) after two to four months. METHODS: Among 90 patients who underwent AVR between September 2002 and April 2003, 31 had both intraoperative 'post-pump' TEE, including transaortic gradients, and TTE at two to four months after surgery. Mean and peak transvalvular gradients were compared between time periods, and a receiver operator curve (ROC) was constructed to test the ability to predict a mean gradient >15 mmHg (upper quartile of patients) on follow up. RESULTS: There was no discernable correlation between mean gradient on intraoperative imaging and at follow up (R2 = 0.09; p = 0.11); for peak gradient there was a statistically significant but extremely weak correlation between time points (R2 = 0.17; p = 0.02). A ROC revealed very poor prediction of high mean gradient on follow up based on mean gradient on intraoperative TEE (area under curve 0.63). CONCLUSION: Gradients on intraoperative TEE immediately after AVR do not correlate with later gradients on TTE. The mean gradient on intraoperative TEE holds no useful predictive value for a high mean gradient at follow up.

Aged↗
PubMed2003

Existence of abdominal aortic aneurysms in patients with thoracic aortic dissections.

OBJECTIVE: The objective of this study was to determine the coexistence or later development of pararenal and infrarenal abdominal aortic aneurysms (AAAs) in patients with thoracic aortic dissections. METHODS: One hundred forty-five patients (95 men, 50 women) encountered from 1992 to 2001 with thoracic aortic dissections-excluding those associated with trauma, those with Marfan's syndrome, and those with thoracoabdominal aortic aneurysms-were studied. The most common risk factors included hypertension (59%) and a history of tobacco use (52%). Type III dissections affected 86 patients (59%), and type I dissections affected the remaining 59 patients (41%). Aortic computed tomography (CT) scans were obtained annually. Data were assessed by univariate and multivariate analyses. RESULTS: Five patients (3%) had a history of AAA repair prior to their thoracic aortic dissection diagnosis-3 were type III dissections and 2 were type I dissections. Twelve patient's (8%) AAAs were diagnosed with the initial CT study of their thoracic aortic dissection. Type III dissections accounted for all but one of these (11 of 12, 92%). Ten additional AAAs (7%) developed in the 128 patients with no initial evidence of an AAA being recognized from 1 to 48 months (average 16 months) after the thoracic aortic dissection was diagnosed. Type III dissections affected 8 of these 10 patients. Among the total 27 AAAs noted in this series, 74% (20 AAAs) were not continuous with the thoracic aortic dissection. In the univariate analysis, age (P =.0002), male gender (P =.044), history of smoking (P =.01), chronic obstructive pulmonary disease (P <.001), duration of dissection (P =.05), and presence of type III dissection (P =.009) were associated with the presence of an AAA. In the multivariate analysis, both chronic obstructive pulmonary disease (odds ratio 5.4, 95% CI, 1.3 to 22.3; P =.02) and age (OR 1.06, 95% CI, 1.02 to 1.11; P =.004) were significant predictors of the development of AAAs. CONCLUSION: This study documented that patients with thoracic aortic dissections are at risk to harbor or develop a later AAA. This finding supports the tenet that abdominal CTs or ultrasound scanning should be mandatory in the follow-up of patients with known thoracic aortic dissections.

Aged↗
PubMed2003

Aortic intimal tears: detection with spiral computed tomography.

PURPOSE: To determine the frequency, locations, and sizes of aortic intimal tears detected using spiral computed tomography (CT). METHODS: CT scans (26 single detector and 26 multidetector studies) from 52 patients with an unoperated aortic dissection and a patent false lumen were evaluated on a workstation. The number, location, and size of aortic tears were recorded and compared between the following groups: acute and chronic dissection, type A and type B, and single detector and multidetector studies. RESULTS: In 52 patients, 129 tears were identified (mean 2.48 per patient, median 2, range 1-7). There were no significant differences in the number or size of tears between the acute and chronic, the type A and type B, or the single detector and multidetector groups (p>0.05). The most common locations for tears were the descending aorta (57, 44%) and the juxtarenal region (26, 20%). Within the type B category, there was no significant difference in tear locations between the acute and chronic groups (p>0.05). The majority of tears (88, 68%) were < or =1 cm in each dimension. Tears in the thoracic aorta were significantly larger than abdominal aortic tears (p<0.05). CONCLUSIONS: All patients with an aortic dissection and a patent false lumen demonstrated one or more aortic intimal tears using spiral CT. Although most tears were small (</=1 cm), they were usually easily visualized.

Acute Disease↗
PubMed2003

The sinotubular junction does not progressively dilate four years after modified subcoronary freestyle stentless tissue aortic valve replacement.

BACKGROUND AND AIM OF THE STUDY: Aortic root dilation at the sinotubular junction (STJ) results in aortic regurgitation associated with normal valves and with a complete subcoronary stentless aortic bioprosthesis. The study aim was to assess for progressive aortic root dilation following modified subcoronary Freestyle aortic valve replacement (AVR), and to compare for differences between implant techniques. METHODS: Aortic root diameter was measured at the annulus, sinuses of Valsalva, STJ and tubular aorta on post-pump transesophageal echocardiograms and on early (3-month) and late (>2 years) transthoracic echocardiograms among 16 patients after modified subcoronary Freestyle valve replacement, 16 after root inclusion, and three after total root replacement. RESULTS: Mean follow up was 3.9 +/- 0.8, 3.3 +/- 0.7 and 3.5 +/- 1.1 years for modified subcoronary, root inclusion and total root patients, respectively. The aortic annulus, sinuses and STJ increased in diameter to similar extents between surgery and three months after modified subcoronary and root inclusion surgery, with no further increase at late follow up (modified subcoronary STJ 18.4 +/- 3.7, 21.1 +/- 3.7 and 20.5 +/- 4.4 mm on intraoperative, early and late echocardiography, respectively; root inclusion STJ 21.8 +/- 3.9, 25.4 +/- 4.6 and 24.4 +/- 4.4 mm, respectively). There were no changes in aortic root diameter after total root replacement (STJ 23.7 +/- 1.2 and 25.7 +/- 6.0 on intraoperative and late follow up, respectively). Aortic regurgitation prevalence was low, and similar between groups. CONCLUSION: Small but significant increases in aortic root dimensions were seen during the first three months after modified subcoronary and root inclusion surgery, with no subsequent change. The early changes were likely caused by resorption of paravalvular edema and hematoma transiently affecting aortic root measurements in the perioperative period. There was no evidence of progressive STJ dilation at 3.9 years after modified subcoronary Freestyle AVR.

Aged↗
PubMed2002

Intravenous milrinone in cardiac surgery.

Phosphodiesterase inhibitors including milrinone produce positive inotropic effects by slowing the hydrolysis of cyclic adenosine monophosphate in the myocardium. With a loading dose of 50 microg/kg followed by an infusion of 0.5 microg x kg(-1) x min(-1), milrinone increases stroke volume index and left ventricular velocity of circumferential fiber shortening after weaning from cardiopulmonary bypass. Milrinone has potential for the treatment and prevention of internal mammary artery spasm because of its vasodilative effect, which is similar to that of papaverine, and is a potent pulmonary vasodilator for patients with right ventricular dysfunction and pulmonary vasoconstriction. Low-dose milrinone may have antiinflammatory properties and potentially can improve splanchnic perfusion.

Cardiac Surgical Procedures↗
PubMed2002

Impact of implant technique following freestyle stentless aortic valve replacement.

BACKGROUND: Stentless aortic bioprostheses have excellent hemodynamics and clinical outcomes. The purpose of the present study was to determine whether implant technique of the Freestyle aortic root bioprosthesis impacts clinical outcomes or hemodynamic performance. METHODS: The long-term multicenter study of the Freestyle stentless aortic bioprosthesis includes 500 consecutive patients implanted using the subcoronary and 162 using the full root technique. Clinical outcomes and echocardiographic hemodynamics were compared through 5 years. RESULTS: There were no differences between groups in time to death, valve-related death, or reoperation. The incidence of operative death was higher in the full root than in the subcoronary group (odds ratio 3.97, p = 0.001). Patients in the subcoronary group were more likely to have New York Heart Association functional class III or IV symptoms at 1 year (1.7% versus 0%, p = 0.04) and 5 years postoperatively (4.4% versus 0%, p = 0.02). Mean gradient was lower (p = 0.0004) and effective orifice area larger (p = 0.04) in the full root group. Left ventricular mass index decreased in both groups. The preponderance of patients in both groups had no or trivial aortic regurgitation through 5 years. CONCLUSIONS: Full root implantation of the Freestyle stentless aortic bioprosthesis was associated with higher operative mortality, but somewhat better hemodynamics, functional class, and freedom from aortic regurgitation. Higher operative mortality argues against the empiric replacement of the ascending aorta in the absence of aortic root pathology. In appropriately selected patients, both implant techniques are viable alternatives for valve implantation.

Aged↗
PubMed2002

Influence of age on outcomes in patients undergoing mitral valve replacement.

BACKGROUND: Although increasing age has been associated with greater risk of mortality for patients undergoing mitral valve replacement, it is less clear whether this elevated risk is related to age-related differences in comorbidity or other clinical characteristics. METHODS: A population of 31,688 patients from The Society of Thoracic Surgeons National Cardiac Database undergoing mitral valve replacement either alone or in combination with coronary artery bypass grafting or tricuspid surgical procedures from 1997 to 2000 was examined to assess age-related variation in clinical features, morbidity, and mortality. Multivariable logistic regression was used to determine the effect of age after adjusting for other known risk factors. A classification tree was used to identify low-risk elderly (> or = 75 years) patients. RESULTS: Operative mortality increased four-fold from 4.1% in patients aged less than 50 years up to 17.0% in patients aged 80 years or more. Similarly, major operative complications (stroke, prolonged ventilation, reoperation for bleeding, renal failure, and sternal infection) also increased with age, rising from 13.5% (age < 50 years) to 35.5% (age > or = 80 years). Multivariable adjustment attenuated the odds of operative mortality, but age remained a significant risk factor. After adjusting for other patient risk factors, age accounted for 13% and 10% of the explainable risk for mortality and morbidity, respectively. Among the elderly, four variables (hemodynamic instability, New York Heart Association class IV, renal failure, and concomitant coronary artery bypass grafting) were identified to distinguish levels of risk, from operative mortality rates exceeding 31% to those with 7.7% mortality. CONCLUSIONS: Operative mortality and morbidity rise with increasing age of patients undergoing mitral valve replacement. Although this excess risk is partially a result of increased comorbid burden and other operative factors, age remains an independent powerful risk factor for operative risk for mitral valve replacement. Understanding the relationship of age with other risk factors for mitral valve replacement can help stratify risk, enabling physicians to identify lower risk patients.

Age Factors↗
PubMed2002

Intraoperative transesophageal echocardiographic assessment of the effect of protamine on paraprosthetic aortic insufficiency immediately after stentless tissue aortic valve replacement.

Mild paravalvular aortic insufficiency (AI) is common immediately after stentless bioprosthetic aortic valve replacement. Although resolution of paraprosthetic jets with protamine has been described, the predictability of resolution has not been addressed. Intraoperative transesophageal echocardiography was performed before and after protamine administration among 2 groups. The first group (n = 20) was used to define the prevalence and severity of paravalvular AI after stentless tissue AVR, and define a threshold value for jet size associated with resolution with protamine. A second group (n = 18) was used to prospectively test the determined threshold. Paravalvular AI occurred in 13 of 20 (65%) patients. Using a threshold value of 0.3 cm or less jet width, prospective testing revealed positive and negative predictive values for AI resolution with protamine of 93% (14 of 15) and 100% (3 of 3), respectively. Protamine administration is associated with resolution of small AI jets immediately after implantation of a stentless aortic bioprosthesis, with a jet width 0.3 cm or less strongly predictive of resolution.

Adult↗
PubMed2002

Operative mortality rate for elective abdominal aortic aneurysm repair is not increased by the presence of a previous or concurrent thoracic or thoracoabdominal aortic dissection.

BACKGROUND: The objective of this study was to determine the likelihood of mortality after abdominal aortic aneurysm (AAA) repair in patients with thoracic or thoracoabdominal aortic dissection. METHODS: Fourteen patients (11 men, three women) with known thoracic or thoracoabdominal aortic dissections underwent elective AAA repair from 1986 to 2001, including three patients with acute dissections (less than 14 days) and 11 patients with chronic dissections (14 days or longer). All 14 patients had type III aortic dissections. Stent graft exclusion of the aortic dissection was performed in one patient before AAA repair. Preoperative patient characteristics, intraoperative events, perioperative complications, and 30-day and 1-year mortality rates were assessed. RESULTS: Elective AAA repair in the setting of thoracic or thoracoabdominal aortic dissection in this series was associated with no 30-day mortality and a 1-year mortality rate of 7.1%. Furthermore, preoperative patient characteristics, intraoperative events, and perioperative complications did not appear to be associated with late, 1-year, mortality. CONCLUSION: Elective AAA repair in the setting of acute or chronic aortic dissection is associated with mortality rates similar to those generally attributed to elective AAA repair without accompanying aortic dissection. Nevertheless, the conduct of the operation is usually complex, especially in the setting of an acute aortic dissection.

Acute Disease↗