Peter Kleine

University of Michigan, Ann Arbor, MI, United States

Are you Peter Kleine?

Claim your profile

Publications (66)141.16 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study investigates the geometry of failing left ventricles with a special focus on apical deformation. A new surgical remodelling technique is evaluated. In 124 patients with impaired left ventricular function (EF<40%) undergoing coronary artery bypass grafting (CABG) left ventricular (LV) geometry was evaluated by MRI scanning before and after surgery. Besides the sphericity index (SI) two further indices were calculated, longitudinal EF (LEF) and an apical conicity index (ACI). The results were compared to 15 patients with coronary heart disease and normal LV function and 10 test persons. In 35 patients with impaired LV function perpendicular apical compression (AC) stitches were placed. In failing left ventricles indexed LV length increased (5.3 ± 0.6 cm/m2 vs. 4.7 ± 0.8 cm/m2 in control patients and 4.6 ± 0.3 cm/m2 in test persons, P=0.03). LEF was reduced (6% ± 4 versus 22% ± 6 and 19% ± 7 P=0.04). The classical SI was 0.56 ± 0.06 in heart failure patients, 0.50 ± 0.05 in control patients and 0.48 ± 0.04 in test persons. The ACI were 0.75 ± 0.06, 0.58 ± 0.06 and 0.57 ± 0.04 respectively (P<0.05), indicating a pronounced dilatation at the apex. After apical compression LEF improved to 15 ± 1%, the ACI to 0.64 ± 0.04 (P=0.04). LVEDV (166 ± 11 mL [AC] vs. 196 ± 14 mL [without AC]) as well as LV-EF (48 ± 3% [AC] vs. 36 ± 2% [without AC]) significantly improved only after remodelling (P<0.05). Apical compression improved ventricular geometry and ventricular function in patients with dialatation of the left ventricular apex.
    The Journal of cardiovascular surgery 08/2012; 53(4):545-52. · 1.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pressure recovery results in Doppler gradients greater than catheter gradients and is well established in association with bileaflet mechanical aortic valves. Because pressure recovery is influenced by orifice geometry, it might manifest differently with various valve prostheses. If true, then the reliability of Doppler echocardiography for the estimation of aortic valve gradients might be different with different prostheses. The purpose of the present study was to test, in an in vitro setting, the degree to which pressure recovery results in Doppler overestimation of gradients for three commonly used aortic valve prostheses. Carpentier Edwards Perimount, Medtronic Mosaic, and St. Jude Medical bileaflet prostheses were tested under various flow conditions in a pulsatile mock flow loop with a normal aorta size. Mean pressure gradient was assessed with transducers 1 cm and 10 cm distal to the valve and with Doppler echocardiography. Pressure recovery was defined as the difference between the Doppler gradient and a 10-cm gradient. The percentage of the maximum pressure gradient composed of pressure recovery and the percentage of pressure recovery complete 1 cm distal to the valve were calculated. There was substantial pressure recovery for all valves in all flow states. Pressure recovery was responsible for 50% or more of the Doppler gradients for almost all conditions and was more than 70% complete within 1 cm for almost all conditions. Multivariate analysis found that flow and valve area (but not valve type) were predictors of pressure recovery; that flow was the major predictor of the percentage of Doppler gradient composed of pressure recovery (with minor contributions from the aorta size and prosthesis type); and that valve type and aorta size were the major predictors of the percentage of pressure recovery complete at 1 cm. In an in vitro model with a normal aorta size, substantial pressure recovery occurred with all three aortic valve prostheses. Although statistically significant differences were found between valve types in the percentage of pressure recovery and percentage of pressure recovery complete at 1 cm, the differences were small and clinically unimportant. Clinically, among patients with an ascending aorta diameter less than 3.0 cm, Doppler echocardiography likely substantially overestimates aortic valve mean gradient, regardless of prosthesis type.
    The Journal of thoracic and cardiovascular surgery 01/2012; 144(2):453-8. · 3.41 Impact Factor
  • Peter Kleine, Mustafa Balci, Anton Moritz
    [Show abstract] [Hide abstract]
    ABSTRACT: Tracheal and esophageal stenosis caused by double aortic arch and Kommerell diverticulum is a rare but important pathologic entity in adult patients. Clinical symptoms are caused by esophageal or tracheal stenosis, or both. The present article describes a surgical method of complete repair with division of the rudimentary left arch, resection of the diverticulum, and transposition of the left subclavian artery. This method was transferred from pediatric patients and led to excellent clinical results in 2 consecutive adult patients compared with the previous technique with division of the left arch alone.
    The Annals of thoracic surgery 02/2011; 91(2):627-9. · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this paper is the retrospective investigation of the clinical outcome and modes of failure leading to reoperation, as well as the report of the long-term results, in a group of young children who underwent epicardial pacemaker implantation. Between 2000 and 2008, 45 young children underwent epicardial pacemaker implantation at 3.2 +/- 2.5 years of age for congenital (n = 27) or post-operative (n = 18) atrioventricular block. The follow-up time was 5.7 years +/- 5 months (range: 6 months to 7.3 years). Five lead malfunction events (11%) were detected during the follow-up time, three of which were due to ventricular lead fracture. All revisions could be performed without complications, and all revised pacemakers showed stable pacing and sensing parameters during long-term follow-up. The actuarial freedom from reoperation at 6 years was 88.8 +/- 2%. Median epicardial ventricular and atrial pacing thresholds were stable and excellent at the latest follow-up, with means of 1.1 +/- 0.5 V and 0.7 +/- 0.8 V, respectively. In our patient cohort of 45 young children, epicardial pacing was associated with a satisfactory clinical outcome and acceptable long-term results. The major cause of reoperation in our series was lead fracture. Reoperations were performed at a low risk.
    Europace 02/2010; 12(4):540-3. · 2.77 Impact Factor
  • The Thoracic and Cardiovascular Surgeon 01/2010; 58. · 0.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Optimal treatment strategies for patients with ischemic cardiomyopathy and moderately reduced left ventricular function remain controversial. We assessed the early and midterm outcomes after surgical revascularization alone versus revascularization and additional left ventricular remodeling in these patients. Between 2000 and 2003, 285 consecutive patients with coronary artery disease and moderately impaired left ventricular function (ejection fraction 30%-40%) were surgically treated with coronary artery bypass grafting alone (group 1, n = 165) or open left ventricular remodeling in addition to revascularization (group 2, n = 120). Preoperatively, the New York Heart Association class, left ventricular ejection fraction, and end-diastolic diameter were comparable. Early and midterm outcomes, hemodynamic performance, and quality of life assessed by Minnesota Quality of Life Questionnaire were evaluated during a mean follow-up period of 70 months. Group 2 patients demonstrated significantly longer ventilation times, higher blood loss, and need for blood transfusion but had significantly lower operative mortality (4.5% compared with 8.5% in group 1). Seven-year follow-up demonstrated survival of 74.3% +/- 8.1% in group 1 versus 84.2% +/- 5.4% in group 2 (P < .05). Follow-up examinations revealed greater improvement of functional class in group 1 with mean 1.7 +/- 0.7 versus 2.03 +/- 0.8 in group 2 (P < .05). Cardiac-related hospital readmissions were comparable (3.8% vs 4.1%, P = .73). Patients with ischemic cardiomyopathy, in whom surgical ventricular remodeling was possible and performed, experienced more perioperative complications but had superior early and midterm outcome regarding survival, functional class, and quality of life.
    The Journal of thoracic and cardiovascular surgery 09/2009; 138(3):663-8. · 3.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Biventricular pacing has been suggested in end-stage heart failure. We present a 59-year-old patient undergoing second re-do CABG (coronary artery bypass graft) and carotid artery endarterectomy. Ejection fraction was 15%, QRS-width 175 ms. Following the carotid and CABG procedure, an implanted single-chamber ICD (implantable cardioverter defibrillator) was upgraded to permanent biventricular DDD pacing by implantation of one epicardial left ventricular and one epicardial atrial electrode. At follow-up two months postoperatively ejection fraction had significantly improved to 45%, the patient underwent stress test with adequate load and reported a good quality of life.
    Cases Journal 02/2009; 2(1):59.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Despite continuous development of anticalcification treatment for bioprosthetic valves, calcification remains one major cause of structural failure. The aim of this study is to investigate changes in hemodynamic performance and leaflet kinematics in progressively calcified pericardial and porcine aortic valve prostheses. Five pericardial (Edwards Perimount Magna) and 5 porcine (Medtronic Mosaic Ultra) aortic valve prostheses (Ø23 mm) were exposed to a high concentration Calcium-phosphate fluid in an in vitro pulse duplicator (300 cycles/minute) for 6 weeks. The prostheses were removed weekly and tested in an artificial circulation system (70 beats/min, Cardiac Output 5 l/min). All prostheses underwent X-ray, computed tomography (CT)-Scan and photographic examination for evaluation of progressive calcification. Leaflet kinematics were visualized with a high-speed camera. Pericardial valves demonstrated faster degeneration with significantly larger radiographic areas of leaflet calcification (16.5+/-4.3% versus 5.6%+/-2.0%) and also significantly higher Ca-uptake (170+/-71 microg/mg versus 103+/-49 microg/mg) after 6 weeks. Despite degeneration systolic function remained superior for pericardial valves (mean effective orifice area [EOA] 1.52+/-0.05 versus 1.28+/-0.11 cm2, P<0.01), but leaflet kinematics showed longer closing times (135+/-11 msec versus 85+/-9 msec after 6 weeks) accompanied by higher regurgitant flow (7.8+/-1.12 mL versus 1.2+/-0.28 mL, P<0.001). In vitro pericardial valves calcified faster and more severe than porcine valves leading to impaired diastolic function with prolongation of closing times and higher closing volume. Systolic function remained almost undisturbed by the calcification process. As a consequence in clinical settings, follow-up examinations for structural valve deterioration in porcine valves should focus on systolic performance, in pericardial valves on diastolic function.
    The Journal of cardiovascular surgery 01/2009; 49(6):817-24. · 1.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the last decade, several sophisticated and accurate imaging methods such as positron emission tomography have been developed in order to evaluate malignant potential in enlarged mediastinal lymph nodes. This case illustrates an unusual presentation of sarcoidosis that mimicked lymphatic metastases of non small cell lung carcinoma. The reported high specificity and sensitivity of positron emission tomography-Computer Tomography regarding mediastinal staging could lead in same cases of false positives to a delaying of stage adapted therapy of non small cell lung carcinoma, showing that despite the recent advances of imaging techniques, such as positron emission tomography-computer tomography, several limitations of this imaging technique are still existing.
    Cases Journal 01/2009; 2:6718.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cardiopulmonary bypass is associated with systemic inflammation that may contribute to increased perioperative mortality. Depletion of circulating leukocytes may reduce the inflammatory response. We studied the effect of a leukocyte depleting filter on leukocyte activation during cardiopulmonary bypass in high risk patients. Fifty patients undergoing coronary artery bypass grafting with a preoperative high risk were randomly placed in an arterial line leukocyte filter group (n = 25) with a leukocyte depleting filter. Blood sampling took place from the arterial line to analyze polymorphnuclear elastase and myeloperoxidase at six time points, including: A) before the induction of anesthesia, B) before the induction of the cardiopulmonary bypass C) 1 min after the release of the aorta clamp, D) the end of the operation, E) 1 h postoperative, and F) 24 h postoperative. Levels of polymorphonuclear elastase, (PMNE), and myeloperoxidase (MPO) were found to be higher after the release of the aortic cross clamp in the leukocyte filter group; these levels remained elevated until 24 hours after surgery and were high in comparison to preoperative baseline levels. The differences in PMNE between both groups at time points C and D (p < 0.005) and E (p < 0.05) were statistically significant. The serum levels of the S-100B and neuron specific enolase (NSE) were found to be elevated between time points C and E in both groups without statistical significance. The in-hospital mortality was 16% (4 patients) in leukocyte filter group and 4% in control group (1 patient). Interestingly, the activation of neutrophils was more pronounced in the LF group. The use of a leucocyte depleting filter was not advantageous for this patient cohort for clinical or biomedical endpoints.
    Agents and Actions 12/2008; 57(12):577-85. · 1.59 Impact Factor
  • The Journal of thoracic and cardiovascular surgery 12/2008; 136(5):1380-1. · 3.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Despite continuous development of anticalcification treatment for biological valve prostheses, calcification remains one major cause of structural failure. The following study investigates hemodynamics and changes in opening and closing kinematics in progressively calcified porcine and pericardial valves in a simulated exercise situation. Five pericardial (Edwards Perimount Magna) and five porcine (Medtronic Mosaic Ultra) aortic valve bioprostheses (23 mm) were investigated in an artificial circulation system (150 beats/min, cardiac output 8l/min). Leaflet kinematics were visualized with a high-speed camera (3000 frames/s). Valves were exposed to a calcifying solution for 6 weeks. Repeated testing was performed every week. All prostheses underwent X-ray and photographic examination including measurement of calcium content for evaluation of progressive calcification. In the exercise situation pericardial valves demonstrated lower pressure gradients initially compared to the porcine valves (8.5+/-1.4 vs 11+/-1.6 mmHg), but significantly higher closing volume (5.3+/-1.2 ml vs 1.2+/-0.2 ml of stroke volume) leading to an equal total energy. Neither valve type demonstrated a significant increase in gradient or closing volume compared to the normal output situation. Opening and closing times were longer for pericardial valves after 6 weeks (opening time 42+/-10 ms vs 28+/-10 ms, closing time 84+/-12 vs 52+/-10 ms after 6 weeks). Pericardial valves calcified faster and more severely leading to an increase in gradients and closure volume. In the exercise situation pericardial valves demonstrated superior systolic function compared to porcine valves. Therefore pericardial valves have some advantage in active patients due to the lower gradients. Total energy loss remained constant during progressive calcification for both valves. Leaflet opening and closing is faster in porcine valves; clinical impact of these findings is not known. Diastolic performance is also important and should always be tested also in vivo.
    European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery 10/2008; 34(5):960-3. · 2.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic resonance imaging was compared with echocardiography and angiography in determining the regurgitant volume in patients with aortic regurgitation. Forty patients were examined at 1.5 T. The regurgitant jet was located using a gradient-echo sequence. Cine measurements were performed to calculate left ventricular function. For flow evaluation, a velocity-encoded breath-hold phase-difference magnetic resonance sequence was used. The degree of aortic regurgitation assessed by magnetic resonance imaging agreed with that of angiography in 28 of 40 (70%) patients, and with the echocardiography result in 80%. Correlation between calculated stroke volume by magnetic resonance cine and flow measurements was very good (r > 0.9). Magnetic resonance imaging enables quick and reliable quantitative assessment of aortic regurgitant volume, and it might be the optimal technique for multiple follow-up studies and assessment of left ventricular function, leading to better evaluation of disease severity and optimization of the timing of valve surgery.
    Asian cardiovascular & thoracic annals 08/2008; 16(4):278-83.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Heart failure is common following aortic valve replacement, and optimal prosthesis function is crucial in this critical clinical setting. The study aim was to investigate the hemodynamic performance and leaflet kinematics of fresh and calcified biological aortic valves in a simulated low stroke volume situation. Edwards Perimount Magna (PM) and Medtronic Mosaic Ultra (MU) valves were investigated in an artificial circulation system (130 beats/min, stroke volume 19 ml), and the results compared to normal output (70 beats/min, stroke volume 70 ml). Leaflet kinematics were visualized using a high-speed camera. All valves were exposed to a calcifying solution for six weeks. In the low- and normal-output situation, the PM valve initially demonstrated lower pressure gradients compared to the MU valve (low output 2.4 +/- 0.16 versus 3.4 +/- 0.19 mmHg), but showed a significantly higher closing volume (up to 19% of stroke volume) leading to an increased total energy loss. Regurgitation for the PM valve was explained by progressively longer opening and closing times. The PM valve calcified faster and more severely, leading to increasing gradients and closure volume. In the low stroke volume situation pericardial valves demonstrated superior systolic performance, but inferior diastolic performance, leading to a higher total energy loss compared to porcine valves. This finding may have clinical relevance in heart-failure patients.
    The Journal of heart valve disease 06/2008; 17(3):317-24. · 1.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Patients with severely impaired left ventricular (LV) function often demonstrate prolonged inter- and intraventricular conduction. This prospective study investigates hemodynamic effects and outcomes of perioperative temporary biventricular pacing in patients with heart failure undergoing heart surgery. 80 consecutive cardiac surgery patients with a LV ejection fraction below 35 % received biventricular stimulation via temporary myocardial electrodes. Group 1 consisted of 40 patients with LV dilatation (mean LVEDD 65 +/- 5 mm), Group 2 of 40 patients with normal or slightly dilated LV (mean LVEDD 52 +/- 4 mm). Hemodynamic parameters were measured immediately, 6 and 24 hours after operation. An increase of cardiac index (CI) and arterial blood pressure with biventricular pacing was observed in 27 patients (Group 1/67.5 %) versus 22 patients (Group 2/55 %) from 2.4 +/- 0.7 l/min/m2 to 3.5 +/- 0.5 l/min/m2 ( P < 0.01). This benefit persisted 6 and 24 hours postoperatively. The remaining patients already showed a higher cardiac index prior to pacing (3.7 +/- 0.9 l/min/m2). In Group 1, the duration of ventilation support and time in the intensive care unit of responding patients was shorter. QRS duration before surgery was not predictive for the response to biventricular pacing. In the majority of patients with reduced LV function, temporary biventricular pacing improves CO and arterial blood pressure after surgery, especially when LV dilatation is present.
    The Thoracic and Cardiovascular Surgeon 03/2008; 56(2):87-92. · 0.93 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Treatment of acute type A aortic dissection remains a surgical challenge because of prolonged operative times, bleeding complications, and a considerable risk of neurologic morbidity and mortality. The following study investigates clinical results after modification of perfusion technique for cardiopulmonary bypass as well as temperature management. Between January 2000 and August 2006, 120 consecutive patients underwent repair of acute type A dissection. Selective antegrade cerebral perfusion through the right subclavian artery combined with mild systemic hypothermia (30 degrees C) was used in all patients. Mean cardiopulmonary bypass time was 144 +/- 53 minutes, and mean myocardial ischemic time was 98 +/- 49 minutes. Isolated cerebral perfusion was performed for 25 +/- 12 minutes. Mean core temperature amounted to 30.1 degrees +/- 2.2 degrees C. Chest tube drainage during the first 24 hours was 525 +/- 220 mL. Mean ventilation time was 54 +/- 22 hours. Elevation of serum lactate levels at 1, 12, and 24 hours postoperatively rose to 22 +/- 14, 18 +/- 11, and 19 +/- 8 mg/dL respectively. We observed new postoperative permanent neurologic deficits in 5 patients (4.2%) and TND in 3 patients (2.5%). The 30-day mortality rate was 5% (n = 6). After a mean follow-up period of 2.8 years, 104 patients (87%) were still alive. Antegrade cerebral perfusion in combination with mild hypothermia offered sufficient neurologic protection in our patient cohort, provided adequate distal organ protection, and reduced perioperative complications in surgery for type A dissection. This perfusion strategy may help in reducing perioperative complications in this particular patient population.
    The Annals of thoracic surgery 03/2008; 85(2):465-9. · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Venoarterial extracorporeal membrane oxygenation is an established treatment option in patients with cardiogenic shock. This report reviews our 3-year experience with this support system with respect to early and midterm outcome, as well as predictors of survival. From January 2003 until November 2006, 45 (0.8%) of 5750 patients undergoing cardiac surgery procedures required the following: temporary extracorporeal membrane oxygenation support coronary artery bypass grafting, n = 20; implantation of a left ventricular assist device, n = 5; heart transplantation, n = 1; heart and lung transplantation, n = 1; coronary artery bypass grafting plus repair of postinfarction ventricular septal defect, n = 3; coronary artery bypass grafting plus mitral valve repair, n = 5; aortic valve replacement, n = 2; coronary artery bypass grafting plus aortic valve replacement, n = 3; and other procedures, n = 5. Extracorporeal membrane oxygenation implantation was performed through the femoral vessels or axillary artery or through the right atrium and ascending aorta. Additional intra-aortic balloon pumps were used in 30 patients. Average patient age was 60.1 +/- 13.6 years. There were 35 male patients. Average duration of extracorporeal membrane oxygenation was 6.4 +/- 4.5 days. Twenty-five patients could be successfully weaned from extracorporeal membrane oxygenation. The 30-day mortality was 53% (24/45 patients). The in-hospital mortality was 71% (32/45 patients). Thirteen (29%) patients could be successfully discharged. After a follow-up period of up to 3 years, 10 (22%) patients were still alive. Extracorporeal membrane oxygenation offers sufficient cardiopulmonary support in adults with similar hospital and midterm survival rates to those of other mechanical support systems. Early indication, alternative peripheral cannulation techniques, and reduced anticoagulation to avoid perioperative bleeding could improve our results with increasing experience.
    The Journal of thoracic and cardiovascular surgery 03/2008; 135(2):382-8. · 3.41 Impact Factor
  • Source
    The Journal of thoracic and cardiovascular surgery 03/2008; 135(2):430-1. · 3.41 Impact Factor
  • Source
    Reida El Oakley, Peter Kleine, David S Bach
    Circulation 02/2008; 117(2):253-6. · 15.20 Impact Factor
  • The Thoracic and Cardiovascular Surgeon 01/2008; 56. · 0.93 Impact Factor

Publication Stats

637 Citations
141.16 Total Impact Points

Institutions

  • 2012
    • University of Michigan
      • Department of Internal Medicine
      Ann Arbor, MI, United States
  • 2002–2011
    • Goethe-Universität Frankfurt am Main
      • Zentrum der Chirurgie
      Frankfurt am Main, Hesse, Germany
  • 2008
    • University Hospital Frankfurt
      Frankfurt, Hesse, Germany