The current state of animal models in research: A review.

Animal models have provided invaluable information in the pursuit of medical knowledge and alleviation of human suffering. The foundations of our basic understanding of disease pathophysiology and human anatomy can largely be attributed to preclinical investigations using various animal models. Recently, however, the scientific community, citing concerns about animal welfare as well as the validity and applicability of outcomes, has called the use of animals in research into question. In this review, we seek to summarize the current state of the use of animal models in research.

Survival after Aortic Valve Replacement for Aortic Regurgitation: Prediction from Preoperative Contractility Measurement.

BACKGROUND: Noninvasive measurement of myocardial contractility (end-systolic wall stress-adjusted change in left ventricular ejection fraction from rest to exercise [ΔLVEF - ΔESS]) predicts heart failure, subnormal LVEFrest, and sudden death in asymptomatic patients with chronic severe aortic regurgitation (AR). Here we assess the relation of preoperative ΔLVEF - ΔESS to survival after aortic valve replacement (AVR). METHODS: Patients who underwent AVR for chronic, isolated, pure severe AR (n = 66) were followed for 13.0 ± 6.4 event-free years. Preoperative ΔLVEF - ΔESS (from combined echocardiographic and radionuclide cineangiographic data) enabled cohort stratification into 3 terciles (-1 to -11% [normal or mild] contractility deficit, -12 to -16% [moderate], and ≤-17% [severe], identical with segregation in our earlier study) to relate preoperative contractility to postoperative survival and to age- and gender-matched US census data. RESULTS: Since AVR, 22 patients died (average annual risk [AAR] for all-cause mortality for the entire co hort = 3.15%). Preoperative ΔLVEF - ΔESS predicted postoperative survival (p = 0.009, log rank test). By contractility terciles, all-cause AARs were 1.44, 2.58, and 6.40%. Survival was lower than among US census comparators (p < 0.02), but the "mild" tercile was indistinguishable from census data (p = ns). By multivariable Cox regression, survival prediction by pre-AVR ΔLVEF - ΔESS was independent of, and superior to, prediction by age at surgery, gender, preoperative functional class, LVEFrest, LVEFexercise, change in LVEFrest to exercise, and LV diastolic or systolic dimensions (p ≤ 0.01, pre-AVR ΔLVEF - ΔESS vs. other covariates). CONCLUSION: In severe AR, preoperative contractility predicts post-AVR survival and may be prognostically superior to clinical, geometric and performance descriptors, potentially impacting on patient selection for surgery.

Incidence, risk factors, and prognostic impact of re-exploration for bleeding after cardiac surgery: A retrospective cohort study.

BACKGROUND: Postoperative re-exploration for bleeding (RB) is a frequent complication following cardiac surgery. We aim to assess incidence, risk factors, and prognostic significance of RB in a large cohort of cardiac patients. MATERIALS AND METHODS: We reviewed prospectively collected data for all patients who underwent cardiac surgery at our institution from 2007 to 2015. Logistic regression analysis was used to identify independent predictors of RB and specific outcomes. Propensity matching using a 1:1-ratio compared outcomes of patients who had RB with patients who did not. RESULTS: During the study period, 7381 patients underwent cardiac operations. Of them, 189 (2.6%) underwent RB. RB was an independent predictor of in-hospital mortality (Odds Ratio (OR):2.62 Confidence Interval (CI):1.38-4.96; p = 0.003), major adverse events (OR:3.94, CI:2.79-5.62; p < 0.001), gastrointestinal events (OR:3.54 CI:1.73-7.24), renal failure (OR:2.44, CI:1.23-4.82), prolonged ventilation (OR:3.83, CI:2.60-5.62, p < 0.001), and sepsis (OR:2.50, CI:1.03-6.04, p = 0.043). Preoperative shock (OR:3.68, CI:1.66-8.13; p = 0.001), congestive heart failure (OR:1.70 CI:1.24-2.32; p = 0.001), and urgent and emergent status (OR:2.27, CI:1.65-3.12 and OR:3.57, CI:1.89-6.75; p < 0.001 for both) were predictors of RB operative mortality. Operative mortality, incidence of major adverse events, gastrointestinal events, and respiratory failure were all significantly higher in the propensity matched RB group (p = 0.050, p < 0.001, p = 0.046, and p < 0.001 respectively). CONCLUSIONS: RB significantly increases in-hospital mortality and morbidity after cardiac surgery.

Transapical transcatheter aortic valve replacement in patients with or without prior coronary artery bypass graft operation.

BACKGROUND: Transapical approach (TA) is an established access alternative to the transfemoral technique in patients undergoing transcatheter aortic valve replacement (TAVR) for treatment of symptomatic aortic valve stenosis. The impact of prior coronary artery bypass grafting (CABG) on clinical outcomes in patients undergoing TA-TAVR is not well defined. METHODS: A single center retrospective cohort analysis of 126 patients (male 41%, mean age 85.8 ± 6.1 years) who underwent TA balloon expandable TAVR (Edwards SAPIEN, SAPIEN XT or SAPIEN 3) was performed. Patients were classified as having prior CABG (n = 45) or no prior CABG (n = 81). Baseline clinical characteristics, in-hospital, 30-day, 6 months and one-year clinical outcomes were compared. RESULTS: Compared to patients without prior CABG, CABG patients were more likely to be male (62.2 vs. 29.6%, p < 0.001) with a higher STS score (11.66 ± 5.47 vs. 8.99 ± 4.19, p = 0.003), history of myocardial infarction (55 vs. 21.1%, p < 0.001), implantable cardioverter defibrillator (17.8 vs. 3.7%, p = 0.017), left main coronary artery disease (42.2 vs. 4.9%, p < 0.001), and proximal left anterior descending coronary artery stenosis (57.8 vs. 16%, p < 0.001). They also presented with a lower left ventricular ejection fraction (%) (42.3 ± 15.3 vs. 54.3 ± 11.6, p < 0.01) and a larger effective valve orifice area (0.75 ± 0.20 cm2 vs. 0.67 ± 0.14 cm2, p = 0.025). There were no intra-procedural deaths, no differences in stroke (0 vs. 1.2%, p = 1.0), procedure time in hours (3.50 ± 0.80 vs. 3.26 ± 0.86, p = 0.127), re-intubation rate (8.9 vs. 8.6% p = 1.0), and renal function (highest creatinine value 1.73 ± 0.71 mg/ml vs.1.88 ± 1.15 mg/ml, p = 0.43). All-cause mortality at 6 months was similar in both groups (11.4, vs. 17.3% p = 0.44), and one-year survival was 81.8 and 77.8% respectively (p = 0.51). On multivariate analysis, the only factor significantly associated with one-year mortality was prior history of stroke (HR, 2.76; 95% CI, 1.06-7.17, p = 0.037). CONCLUSION: Despite the higher baseline clinical risk profile, patients with history of prior CABG undergoing TA-TAVR had comparable in-hospital, 6 months and one-year clinical outcomes to those without prior CABG.

Gastrointestinal complications after mitral valve surgery.

INTRODUCTION: Gastrointestinal (GI) complications are well-recognized risks of open heart surgery. However, open heart surgery comes in different shapes and sizes with widely varying pre-operative, intra-operative and post-operative pathologies. The aim of this study was to examine the etiology and risk factors for GI complications after mitral valve surgery. METHODS: A retrospective analysis of 565 patients who underwent mitral valve surgery from 2003-2005 was performed. Prospectively collected data included preoperative risk factors, cardiac status, intra-operative data, postoperative GI complications and mortality. Survival was analyzed using log-rank analysis. RESULTS: In this study population, 13 patients (2.3%) had 16 GI complications after mitral valve surgery resulting in an overall mortality of 0.7%. Complications included GI bleed (n = 9), cholecystitis (n = 3), perforated diverticulitis (n = 1) and ischemic bowel (n = 3). By univariate analysis, a history of hypertension, chronic renal insufficiency (CRI), hypercholesterolemia, myocardial infarction, congestive heart failure, cardiogenic shock, emergency valve surgery, coronary artery bypass surgery and preoperative vasopressor use were each associated with an increased incidence of GI complications (p <0.05). No increased incidence was seen in patients with atrial fibrillation. On multivariate analysis adjusted for age, cardiogenic shock (OR 8.1; 95% CI, 1.9-34.8), CRI (OR 8.1; 95% CI, 2.2-30.0) and vasopressor use (OR 6.5; 95% CI, 1.3-31.0) remained significant (p <0.02). Mean survival (3.2 vs. 5.4 years) was significantly lower (p <0.05) in those with GI complications. CONCLUSIONS: GI complications after mitral valve surgery are infrequent, with a higher incidence in those with cardiogenic shock, CRI or requiring vasopressors. Pre-operative hemodynamic instability may be a bellwether for potential GI complications and should be of more prominent concern in this cohort of patients.

A novel method for percutaneous insertion of a right ventricular assist device.

Right heart failure is a rare but often fatal complication both in the pre- and postoperative setting. Right heart support with a ventricular assist device inserted in the operating room through median sternotomy can be a time-consuming procedure that requires a reoperation for removal. In cases of urgent need of right heart support, a percutaneous technique option may be of benefit. We present our initial experience with a percutaneously inserted right ventricular assist device (RVAD) in an elderly patient with severe right heart failure. An 81-year-old female patient underwent combined aortic and mitral valve replacement at our institution. During the first postoperative evening, the patient sustained sudden cardiovascular collapse and a bedside transesophageal echocardiogram revealed severe right heart failure. A coronary angiogram showed thrombosis of the right coronary artery, which was cleared with a suction device. As a result of the patient's critical condition, it was decided that an RVAD was needed as a bridge to recovery. The patient's condition improved significantly almost immediately. Her right heart function recovered over the next few days and the RVAD was removed at the bedside. She made a complete recovery and was discharged home. This patient is a prime example that a totally RVAD can be inserted in urgent situations easily and safely under fluoroscopic and echocardiographic guidance. More clinical experience with percutaneous RVADs is required to establish this technique as an alternative equivalent to the traditional open method. Right heart failure complicates many heart diseases both in the pre- and the postoperative setting. In cases of urgent need of right heart support, a percutaneous technique of a RVAD is needed for a successful outcome. We present our initial experience with a percutaneously inserted RVAD in an elderly patient with severe postoperative right heart failure.

Usefulness of preoperative exercise tolerance to predict late survival and symptom persistence after surgery for chronic nonischemic mitral regurgitation.

Exercise duration during exercise treadmill testing (ETT) predicts long-term outcome among asymptomatic patients with mitral regurgitation. However, the prognostic value of preoperative exercise duration in patients who undergo mitral valve surgery is unknown. We examined findings among 45 prospectively followed (average 9.2 ± 4.3 years) patients (aged 54.8 ± 12.0 years, 45% men) with chronic isolated severe MR who underwent ETT before mitral valve surgery to test the hypotheses that exercise duration predicts long-term postoperative survival and persistent symptoms within 2 years after operation. During follow-up, 11 patients died; of these, 8 had persistent symptoms. Among patients who exercised >7 minutes, average annual postoperative all-cause and cardiovascular mortality risks were 0.75% (both endpoints) versus 5.4% and 4.8%, respectively, versus those who exercised ≤7 minutes (p = 0.003 all-cause, p = 0.007 cardiovascular). Exercise duration predicted postoperative deaths (p <.02 all cause, p <.04 cardiovascular) even when analysis was adjusted for preoperative variations in age, gender, medications, history of atrial fibrillation, and peak exercise heart rates. Other ETT, echocardiographic, and clinical variables were not independently associated with these outcomes when exercise duration was considered in the analysis. Preoperative exercise duration also predicted postoperative (New York Heart Association functional class ≥II) symptom persistence (p = 0.012), whereas other ETT, echocardiographic and clinical variables did not (NS, all). In conclusion, among patients who undergo surgery for chronic nonischemic mitral regurgitation, preoperative exercise duration, unlike many commonly used descriptors, is useful for predicting postoperative mortality and symptom persistence. Future research should determine whether interventions to improve exercise tolerance before mitral valve surgery can modify these postoperative outcomes.

Nonischemic mitral regurgitation: prognostic value of nonsustained ventricular tachycardia after mitral valve surgery.

BACKGROUND: Nonsustained ventricular tachycardia (VT), frequent in unoperated severe mitral regurgitation (MR), confers mortality risk [sudden death (SD) and cardiac death (CD)]. The prognostic value of VT after mitral valve surgery (MVS) is unknown; we aimed to define this prognostic value and to assess its modulation by left (LV) and/or right (RV) ventricular ejection fraction (EF) for mortality after MVS. METHODS: In 57 patients (53% females, aged 58 ± 12 years) with severe MR prospectively followed before and after MVS, we performed 24-hour ambulatory electrocardiograms approximately annually. LVEF and RVEF were determined within 1 year after MVS by radionuclide cineangiography. RESULTS: During 9.52 ± 3.49 endpoint-free follow-up years, late postoperative CD occurred in 11 patients (7 SD, 4 heart failures). In univariable analysis, >1 VT episode after MVS predicted SD (p < 0.01) and CD (SD or heart failure; p < 0.04). Subnormal postoperative RVEF predicted CD (p < 0.04). When adjusted for preoperative age, gender, etiology or antiarrhythmics, both postoperative VT and RVEF predicted CD (p ≤ 0.05). When postoperative VT and RVEF were both in the multivariable model, only subnormal RVEF predicted CD (p < 0.04). Among those with normal RVEF, VT >1 episode predicted SD (p = 0.03). CONCLUSION: Postoperative VT and subnormal RVEF predict late postoperative deaths in nonischemic MR. Their assessment may aid patient management.

Surgical revision after percutaneous mitral repair with the MitraClip device.

BACKGROUND: Percutaneous mitral repair with the MitraClip device (Evalve, Menlo Park, CA) has been reported. Preserving conventional surgical options in the event of percutaneous treatment failure is important. We describe surgical treatment at varying intervals after the MitraClip procedure in 32 patients. METHODS: One hundred seven patients with moderate-to-severe or severe mitral regurgitation who were either symptomatic (91%) or, if asymptomatic (9%), had evidence of left ventricular dysfunction were enrolled as part of the Endovascular Valve Edge-to-Edge REpair STudy (EVEREST) phase I registry study or as "roll-in" subjects in the EVEREST II study. Thirty-two of the 107 patients (30%) underwent surgery after an attempted MitraClip procedure. RESULTS: Of the 32 patients undergoing post-clip mitral valve surgery, 23 patients (72%) had one or more clips implanted and 9 patients (28%) received no clip implant. The indications for mitral valve surgery in the 23 patients with a clip included partial clip detachment (n = 10), residual or recurrent mitral regurgitation greater than 2+ (n = 9), and other (atrial septal defect [n = 2], device malfunction [n = 1], and incorrectly diagnosed mitral stenosis [n = 1]). Twenty-seven of 31 patients (87%) underwent the surgical procedure planned before surgery (planned procedure unknown in 1 patient). Four of 25 patients (16%) with planned repair underwent mitral valve replacement. CONCLUSIONS: Standard surgical options were preserved in patients who had surgery after percutaneous repair with the MitraClip device. Successful repair was feasible in the majority of patients after the MitraClip procedure, with repair performed as late as 18 months after clip implantation.

Intravenous leiomyomatosis with intracardiac extension: a single-institution experience.

OBJECTIVE: The aim of this study was to outline the surgical management and outcomes for patients diagnosed with intravenous leiomyomatosis with intracardiac extension at a single institution. STUDY DESIGN: This was a retrospective review of patients diagnosed with intravenous leiomyomatosis with intracardiac extension between 2002-2008. RESULTS: Four patients were identified. The surgical approach in 3 (75%) patients was a single-stage operation. Four (100%) patients presented with cardiac symptoms: 3 (75%) with syncope and 1 (25%) with an abnormal electrocardiogram. Mean age at presentation was 48 years (range, 42-58 years). Complete resection of tumor was obtained in 1 (25%) patient and 3 (75%) patients experienced incomplete resection. Mean follow-up, including surveillance imaging, was 25.5 months (range, 8-57 months) and all 4 patients (100%) are currently free of recurrence. CONCLUSION: Surgical excision remains an effective therapy for treating patients with benign metastasizing leiomyomatosis. Incomplete surgical resection may result in favorable response.

Low-dose spironolactone: effects on artery-to-artery vein grafts and percutaneous coronary intervention sites.

The efficacy of vein grafts used in coronary and peripheral artery bypass is limited by excessive hyperplasia and fibrosis that occur early after engraftment. In the present study, we sought to determine whether low-dose spironolactone alleviates maladaptive vein graft arterialization and alters intimal reaction to coronary artery stenting. Yorkshire pigs were randomized to treatment with oral spironolactone 25 mg daily or placebo. All animals underwent right carotid artery interposition grafting using a segment of external jugular vein and, 5 days later, underwent angiography of carotid and coronary arteries. At that time, a bare metal stent was placed in the left anterior descending artery and balloon angioplasty was performed on the circumflex coronary artery. Repeat carotid and coronary angiograms were performed before euthanasia and graft excision at 30 days. Angiography revealed that venous grafts of spironolactone-treated animals had lumen diameters twice the size of controls at 5 days, a finding that persisted at 30 days. However, neointima and total vessel wall areas also were 2- to 3-fold greater in spironolactone-treated animals, and there were no differences in vessel wall layer thicknesses or collagen and elastin densities. In the coronary circulation, there were no differences between treatment groups in any vessel wall parameters in either stented or unstented vessels. Taken together, these observations suggest that low-dose spironolactone may exert a novel protective effect on remodeling in venous arterial grafts that does not depend on the reduction of hyperplastic changes but may involve dilatation of the vessel wall.

Acceptability and psychometric properties of the Minnesota Living With Heart Failure Questionnaire among patients undergoing heart valve surgery: validation and comparison with SF-36.

BACKGROUND: Health-related quality of life (HQOL) enhancement is a major objective of valvular surgery (VS), but assessments have been limited primarily to generic measures that may not be optimally responsive to intervention. Disease-specific instruments have been used in heart failure (HF), commonly associated with valve disease, but have been neither validated nor routinely applied among patients undergoing VS. METHODS AND RESULTS: We administered the Minnesota Living with Heart Failure (MLHFQ) and SF-36 questionnaires preoperatively (T(0)) to 50 patients undergoing VS and at 1 (T(1)) and 6 months (T(2)) after VS. Performance of MLHFQ was evaluated and compared with SF-36. MLHFQ completion rates were >98% (NS vs. SF-36); Cronbach's alpha was > or = 0.9 (total score, dimensions), supporting internal reliability. Confirmatory factor analysis verified good model fit for physical/emotional domain items (relative chi-squares < 3.0, critical ratios > 2.0, both instruments), supporting structural validity. Spearman coefficients correlating MLHFQ with parallel SF-36 domains were moderate to high (0.6-0.9; P < or = .001: T(0)-T(2)), supporting convergent validity. Baseline HQOL was poorest in patients with HF (P < or = .05 [both instruments]), supporting criterion validity. Responsiveness (proportional HQOL change scores: T(0) vs. T(2)) to VS was greater with MLHFQ vs. SF-36 (P < or = .002). CONCLUSIONS: Among patients undergoing VS, the MLHFQ is highly acceptable and maintains good psychometric properties, comparing favorably with SF-36. These findings suggest its utility for measuring disease-specific HQOL changes after VS.

Cardiac surgery in select nonagenarians: should we or shouldn't we?

BACKGROUND: Patients aged 90 years and older represent a rapidly growing subset of the population, many of whom are functionally limited by cardiovascular disease. Clinical decision making about cardiac surgical intervention in nonagenarians is hindered by a paucity of data examining survival outcomes in this population. METHODS: A consecutive series of nonagenarians who underwent cardiac operations between 1995 and 2004 were retrospectively reviewed. Data collection included baseline preoperative clinical status, intraoperative characteristics, and perioperative course. Area under the Kaplan-Meier survival estimate method was used to calculate mean survival. RESULTS: Cardiac surgical procedures were done in 49 patients (51% male); their mean age was 91.9 years (range, 90 to 97 years). Operative mortality was 8% (n = 4). Multivariate Cox proportional hazards models found preoperative chronic renal insufficiency (hazard ratio [HR], 4.88; 95% confidence interval [CI], 1.53 to 15.55; p = 0.007) and ejection fraction (HR, 0.96; 95% CI, 0.93 to 1.00; p = 0.033) were independently associated with death. Overall mean survival was 5.1 +/- 0.5 years (median, 5.2 years). Quality of life outcomes were similar to that of two related norm-based populations based on age and disease process. CONCLUSIONS: Cardiac surgical procedures can be performed safely and with therapeutic benefit in carefully selected nonagenarians. We consider physiologic indicators, social factors, and patient preferences to be the main determinants in the patient selection process. Our results support the need for more proactive intervention in symptomatic nonagenarian patients as it relates to earlier consideration of elective, rather than emergency cardiac operations.

Improvement of outcomes after coronary artery bypass II: a randomized trial comparing intraoperative high versus customized mean arterial pressure.

BACKGROUND AND AIM OF THE STUDY: The objective of this randomized trial was to compare the efficacy of two strategies of hemodynamic management during cardiopulmonary bypass (CPB) on morbidity, mortality, cognitive complications and deterioration in functional status. METHODS: Patients scheduled to undergo primary elective CABG were eligible. In one group, mean arterial pressure target during CPB was 80 mmHg ("high" MAP group); in the other group, MAP target was determined by patients' pre-bypass MAP ("custom" MAP group). The principal outcomes were mortality, major neurologic or cardiac complications, cognitive complications or deterioration in functional status. RESULTS: Of 412 enrolled patients, 36% were women, with overall mean age of 64.7 +/- 12.3 years. Duration of bypass was identical for the two randomization groups. Overall complication rates were similar: 16.5% of the high group and 14.6% of the custom group experienced one or more neurologic, cardiac or cognitive complications. When only cardiac and neurologic morbidity and mortality were considered, the rates were 11.7% and 12.6%, in the high and custom groups, respectively. The aggregate outcome rate, including functional deterioration, was 31.6% in the high group and 29.6% in the custom group. CONCLUSIONS: There were no statistically significant differences between the high MAP group and the custom MAP group for the combined outcome of mortality cardiac, neurologic or cognitive complications, and deterioration in the quality of life.

Reoperations on the ascending aorta and aortic root in patients with previous cardiac surgery.

BACKGROUND: First time operations on the ascending aorta are performed with low mortality, few complications, and excellent long-term results. Reoperations for aortic pathology in patients with previous cardiac surgery carry significantly more risk. Technical issues during the procedure, as well as age, preoperative New York Heart Association class, and perioperative renal dysfunction, have been shown to contribute heavily to worse outcomes. We analyzed our results with aortic reoperations with the intent of further reducing surgical risk through alterations in surgical technique or patient selection. METHODS: From July 1997 until October 2005, 147 patients having previous cardiac surgery presented with aneurysm or dissection of the ascending aorta or root. Perioperative data were retrospectively analyzed. Morbidity, mortality, and risk factors for these events were calculated. RESULTS: Eight patients expired (5.4%) after their reoperation. Significant (p < 0.05) univariate risk factors for mortality included age greater than 75 years (< 0.001), previous coronary artery bypass grafting (CABG) (< 0.008), cardiopulmonary bypass greater than 240 minutes (< 0.01), need for intraaortic balloon pump support (< 0.001), need for new CABG (< 0.007), postoperative cerebrovascular accident (< 0.032), and tracheostomy (< 0.003). Age 75 years or older (p < 0.025) was the only significant variable for death by multivariate analysis. A majority of patients (n = 87, 60%) required circulatory arrest to complete their procedure. However, neither arch involvement nor type of aortic root procedure was predictive of perioperative mortality. CONCLUSIONS: Surgery on the ascending aorta and root in patients who have had previous cardiac surgery can be performed with low mortality. Advanced age and significant coronary disease may negatively influence surgical results.

Epicardial beating heart cryoablation using a novel argon-based cryoclamp and linear probe.

OBJECTIVE: Epicardial, beating heart cryoablation for the treatment of atrial fibrillation may be limited by heat from intracardiac blood flow. We therefore evaluated the ability to create cryolesions using an argon-based cryoclamp device, which temporarily occludes blood flow and facilitates transmurality. METHODS: Six mongrel dogs underwent sternotomy. A clamp employing a 10-cm argon-based linear cryoablation device was used epicardially to isolate the pulmonary veins and left atrial appendage. After clamping of lesions, the probe was removed from the cryoclamp device, and the remaining linear lesions, analogous to the Cox maze III, were performed. Pulmonary vein stenosis was evaluated with the use of magnetic resonance imaging. Left atrial function and pulmonary venous flow velocities were assessed with transesophageal echocardiography. Transmurality was confirmed both electrically and histologically. Animals were then put to death at 30 days. RESULTS: All acute and chronic cryoclamp lesions produced conduction block. There was no change in right (RPV) or left pulmonary vein (LPV) diameter on the basis of magnetic resonance imaging at baseline and at planned death (RPV-1, 19.6 +/- 2.9 mm vs 16.9 +/- 2.8 mm, P = .22; RPV-2, 13.2 +/- 2.0 mm vs 11.8 +/- 1.6 mm, P = .22; and LPV, 12.2 +/- 2.4 mm vs 11.2 +/- 1.9 mm, P = .30). Left atrial function and pulmonary venous flow velocities were unchanged. Tissue sections determined transmurality in 93% of cryoclamp lesions and 84% of linear ablations performed with the 10-cm malleable probe. CONCLUSIONS: Epicardial application of this cryoclamp device on the beating heart produced transmural lesions, which persisted 30 days. Linear epicardial cryoablation was not as effective as the cryoclamp device at producing consistent transmural lesions. This novel, versatile device may be useful in treating patients with atrial fibrillation on the beating heart without cardiopulmonary bypass.

Heparin sensitivity test for patients requiring cardiopulmonary bypass.

Anticoagulation for the open heart surgery patient undergoing cardiopulmonary bypass (CPB) is achieved with the use of heparin. The industry standard of activated clotting time (ACT) was used to measure the effect of heparin. The commonly acceptable target time of anticoagulation adequacy is 480 seconds or greater. Some patients, however, exhibit resistance to standard dosing of heparin and do not reach target anticoagulation time (480 seconds). Antithrombin III deficiency has been previously cited as the cause of heparin resistance. Early detection of heparin resistance (HR) may avoid both the delayed start of CPB and inadequate anticoagulation, if emergency bypass is required. An anticoagulation sensitivity test (AST) was developed by adding 12 units of porcine mucosa heparin to the ACT tube (International Technidyne, celite type). Before anticoagulation, 4 mL of blood was drawn from the patient arterial line. Following the manufacturer's instructions, 2 mL of blood was added to each tube (ACT-baseline and ACT-AST). Three minutes after anticoagulation with 4 mg heparin/kg body weight, a second sample (ACT-CPB) was taken to determine anticoagulation adequacy. The ACT times of each sample were recorded for 300 procedures occurring during 2004 and were retrospectively reviewed. Heparin resistance occurred in approximately 20% of the patients (n = 61). In 54 patients, heparin resistance was predicted by the ACT-AST. This was determined by the presence of an ACT-AST time and an ACT-CPB that were both < 480 seconds. The positive predictive value was 90%, with a false positive rate of 3%. Heparin resistance occurs in patients undergoing CPB. We describe a simple and reliable test to avoid the delays of assessing anticoagulation for CPB (90% positive predictive value). Depending on program guidelines, patients can be given additional heparin or antithrombin III derivatives to aid in anticoagulation. An additional ACT must be performed and reach target times before CPB initiation. Testing of patient blood before the time of incision for sensitivity to heparin is a way to avoid a delay that can be critical in the care of the patient. Commercial tests are available, but efficacy data are limited, and they lead to added inventory expense. This method of titrating a diluted heparin additive, mixed with patient blood in a familiar ACT test, has proven to be an inexpensive and reliable test to predict patient's sensitivity to heparin.

No-clamp technique for valve repair or replacement in patients with a porcelain aorta.

BACKGROUND: Patients requiring valvular heart surgery may have circumferential calcification of the ascending aorta. A variety of creative procedures have been described for managing this "porcelain aorta." We describe a technique based on replacement of the ascending aorta and proximal arch under profound hypothermic circulatory arrest, followed by the valve procedure. METHODS: Twenty-five consecutive patients with a porcelain aorta were referred for heart valve surgery. In every case the aorta was replaced under circulatory arrest before the valve procedure. Postoperative morbidity, mortality, and univariate risk factors for death were calculated. Fisher's exact test defined significant perioperative variables with a p value less than 0.05. RESULTS: Of 25 patients, 23 (92%) survived the surgery to hospital discharge. One patient had a stroke (4%) and 2 patients (8%) required reexploration for bleeding. Risk factors for perioperative death by univariate analysis included age more than 78 years (p < 0.009), cardiopulmonary bypass time longer than 200 minutes (p < 0.0001), reexploration for bleeding (p < 0.02), need for intra-aortic balloon pump support (p < 0.001), and postoperative gastrointestinal complications (p < 0.001). CONCLUSIONS: Valve replacement or repair in the patient with a porcelain aorta can be safely accomplished with a technique based on aortic replacement under circulatory arrest. Elderly patients requiring extensive procedures and prolonged periods on bypass have a substantially increased risk for postoperative complications and death.

Surgical treatment of atrial fibrillation using argon-based cryoablation during concomitant cardiac procedures.

BACKGROUND: The development of ablative energy sources has simplified the surgical treatment of atrial fibrillation (AF) during concomitant cardiac procedures. We report our results using argon-based endocardial cryoablation for the treatment of AF in patients undergoing concomitant cardiac procedures. METHODS AND RESULTS: Sixty-three patients with AF who were undergoing concomitant cardiac procedures had the same left atrial endocardial lesion set using a flexible argon-based cryoablative device. Mean age was 65.1+/-1.3 years. Sixty-two percent had permanent AF, whereas 38% had paroxysmal AF. Mean duration of AF was 30.5+/-4.8 months. Mean left atrial diameter was 5.5+/-0.1 cm. Mean ejection fraction was 45+/-1.4%. All endocardial lesions were performed for 1 minute once tissue temperature reached -40 degrees C. Follow-up echocardiograms were obtained to determine freedom from AF. Kaplan-Meier analysis demonstrated an 88.5% freedom from AF rate at 12 months. Ablation time was 16.8+/-0.6 minutes. There were no in-hospital deaths and no strokes. Twelve patients (19%) required postoperative permanent pacemaker placement. CONCLUSIONS: Cryoablation using this flexible argon-based device for the treatment of AF during concomitant cardiac procedures was safe and effective, with 88.5% of patients free from AF at 12 months.

Comparison of open versus bedside percutaneous dilatational tracheostomy in the cardiothoracic surgical patient: outcomes and financial analysis.

BACKGROUND: The clinical and financial outcomes of a change in practice from traditional tracheostomy (open) to bedside percutaneous dilatational tracheostomies (PDT) was evaluated in patients who underwent cardiothoracic surgery. METHODS: During 3 years, 86 tracheostomies were performed in more than 4,000 patients who underwent cardiac surgery, 59 open and 27 PDT. A retrospective analysis was performed comparing clinical and financial outcomes of the two groups. RESULTS: There were no significant differences in demographics, medical histories, operations, or complications between open and PDT except the open group experienced more postoperative arrhythmias (70% [41 of 59] versus 44% [12 of 27], p < 0.05). Total savings associated with 1 year of PDT was $84,000, for a projected discounted savings of $283,000 during the study period. A sensitivity analysis of critical economic variables (number of tracheostomies per year, cost of operating room per minute, cost of intensive care unit bed per day) was included to evaluate the impact on cost savings. The net present value analysis, which discounts future savings by an appropriate interest rate, yielded a range of projected savings of PDT more than 5 years of $73,000 to $541,000 with a best estimate of $304,000 using figures established from our 3-year experience with PDT. Sensitivity analysis of the net present value for each critical variable was $227,000 per day of reduced intensive care unit length of stay, $180,000 per cost of operating room avoidance, $100,000 per intensive care unit bed cost per day, and $11,000 per additional tracheostomy per year. CONCLUSIONS: There were no significant clinical differences between open and PDT in cardiac surgery patients during the 3-year study period; however, PDT offered significant cost savings.