Protein phosphatase mRNA expression in Purkinje cells of staggerer and reeler mutant mice

Orthotopic heart transplantation (OHT) with bicaval and pulmonary venous anastomoses avoids the large atrial anastomoses of the standard biatrial technique. To determine whether the bicaval technique improves atrial performance, we used Doppler echocardiography to study 13 patients with bicaval OHT, 15 with biatrial OHT, and 8 normal subjects. All were in sinus rhythm and free of rejection. Left atrial size, transmitral (M) and late diastolic (A) mitral flow velocity integrals were measured. Atrial transport (A/M, %) and atrial ejection force (kilodynes, calculated from peak A-wave velocity and mitral orifice area) were assessed. Left atrial dimensions in the bicaval (4.3 +/- 0.5 cm) and biatrial groups (4.9 +/- 0.9 cm) were larger than in controls (3.3 +/- 0.8 cm, p < 0.05). Left atrial transport (37% +/- 12% and 35% +/- 12%) and ejection force (14.1 +/- 6.9 kdyne and 10.2 +/- 7.8 kdyne) were similar in the bicaval group and controls (p not significant) but were significantly lower in the biatrial group (20% +/- 19% and 3.6 +/- 4.0 kdynes, p < 0.05). The bicaval and pulmonary venous technique of OHT produces more physiologic atrial function compared with the biatrial technique as evidenced by greater atrial ejection force and more normal atrial transport.     

Resting hemodynamics after total versus standard orthotopic heart transplantation in patients with high preoperative pulmonary vascular resistance

OBJECTIVE: Pretransplant pulmonary vascular resistance > or = 4 Wood-units predisposes to right ventricular failure after heart transplantation. Total orthotopic heart transplantation with bicaval and pulmonary venous anastomoses offers synchronous contractions of the atria and a normal ventricular filling pattern, but requires longer ischemic time than standard orthotopic heart transplantation. To test if total orthotopic heart transplantation improves resting hemodynamics in pts with high preoperative pulmonary vascular resistance, we analyzed 65 pts with standard and 65 with total orthotopic heart transplantation transplanted between 12/88 and 7/94. Of these, 18 with total and 15 with standard orthotopic heart transplantation had a preoperative pulmonary vascular resistance > or = 4 Wood-units. METHODS: Right heart catheterization data were obtained at each endomyocardial biopsy. All data from biopsies at both 2 weeks and 1 year posttransplant that were free from humoral or greater than 1A cellular rejection (9 versus 13 pts) were included in a two way ANOVA. Pts with postop pacemakers, atrial fib or beta-blocker therapy at the time of biopsy were excluded. RESULTS: Ischemic time was different (172 +/- 44 versus 142 +/- 28 min, P = 0.03). Demographics, NYHA class, pre-TX hemodynamics, donor age and inotropes were similar. Cardiac output and index were higher in the total orthotopic group at 2 weeks (6.5 +/- 1.7 versus 5.1 +/- 1.0 l/min; 3.4 +/- 0.9 versus 2.8 +/- 0.6 l/min per m2) and 1 year (7.1 +/- 2.0 versus 4.9 +/- 1.1 l/min, P = 0.002; 3.6 +/- 1.1 versus 2.6 +/- 0.5 l/min per m2, P = 0.009). Right atrial and pulmonary arterial mean pressure (mmHg) were lower with total orthotopic heart transplantation at 2 weeks (6 +/- 4 versus 9 +/- 5, P = 0.04; 22 +/- 3 versus 25 +/- 7, P = 0.1) and 1 year (5 +/- 2 versus 7 +/- 3, P = 0.02; 19 +/- 4 versus 25 +/- 7, P = 0.03). Pulmonary capillary wedge pressure (mmHg) was borderline nonsignificant (11 +/- 4 versus 13 +/- 7 at 2 weeks, 8 +/- 3 versus 14 +/- 5 at 1 year, P = 0.055), as well as pulmonary vascular resistance (1.9 +/- 1 versus 2.5 +/- 1 at 2 weeks, 1.5 +/- 0.6 versus 2.7 +/- 1.7 WU at 1 year, P = 0.051). CONCLUSIONS: Total orthotopic heart transplantation improves cardiac output and index in pts with high preoperative pulmonary vacular resistance. There is a lower mean RA and PA pressure perhaps due to less tricuspid and mitral regurgitation. In view of the frequently observed restrictive filling pattern after cardiac transplantation, total orthotopic heart transplantation can be beneficial until this pattern has subsided by preserving atrioventricular synchrony and offering better atrial transport.     

Atrial septal aneurysm: a new classification in two hundred five adults

Atrial septal aneurysm is a localized "saccular" deformity, generally at the level of the fossa ovalis, which protrudes to the right or the left atrium or both. For 39 months we prospectively analyzed 205 consecutive patients in whom atrial septal aneurysm was diagnosed echocardiographically. The direction and movement of atrial septal aneurysms were carefully studied in multiple views, and, according to our findings, we now propose a new classification: type 1R if the bulging is in the right atrium only, type 2L if the bulging is in the left atrium only, type 3RL if the major excursion bulges to the right atrium and the lesser excursion bulges toward the left, type 4LR if the maximal excursion of the atrial septal aneurysm is toward the left atrium with a lesser excursion toward the right atrium, type 5 if the atrial septal aneurysm movement is bidirectional and equidistant to both atria during the cardiorespiratory cycle. We found an incidence of 1.9%, a mean age of 63 years (25 to 97 years), a female/male ratio of 2:1, valvular regurgitation 74%, hypertension 64%, left ventricular hypertrophy 38%, coronary heart disease 32%, patent foramen ovale 32%, pulmonary hypertension 31%, stroke 20%, dysrhythmias 16%, valvular prolapse 15%, and atrial septal defect 3%. No differences were found between mobile and motionless types of atrial septal aneurysm. However, differences were found between predominantly left bulging or right bulging atrial septal aneurysm (134 versus 57 patients), as well as other variables. All types of atrial septal aneurysm have particular clinical or echocardiographic characteristics. The new classification is a complete, simple, and practical form. Atrial septal aneurysm is associated with congenital and acquired heart diseases but also can present as an isolated abnormality.     

Improved atrial function in bicaval versus standard orthotopic techniques in cardiac transplantation

Atrial geometry is preserved in the bicaval technique of cardiac transplantation. Using Doppler echocardiography, we investigated the impact of this technique on preservation of atrial function and found that echocardiographic indexes of atrial function are improved in bicaval cardiac transplants versus the standard orthotopic transplants.     

Color Doppler regurgitant jet area for evaluating eccentric mitral regurgitation: an animal study with quantified mitral regurgitation

OBJECTIVES: The purpose of the present study was to rigorously evaluate the accuracy of the color Doppler jet area planimetry method for quantifying chronic mitral regurgitation. BACKGROUND: Although the color Doppler jet area has been widely used clinically for evaluating the severity of mitral regurgitation, there have been no studies comparing the color jet area with a strictly quantifiable reference standard for determining regurgitant volume. METHODS: In six sheep with surgically produced chronic mitral regurgitation, 24 hemodynamically different states were obtained. Maximal color Doppler jet area for each state was obtained with a Vingmed 750. Image data were directly transferred in digital format to a microcomputer. Mitral regurgitation was quantified by the peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions determined using mitral and aortic electromagnetic flow probes. RESULTS: Mean regurgitant volumes varied from 0.19 to 2.4 liters/min (mean [+/- SD] 1.2 +/- 0.59), regurgitant stroke volumes from 1.8 to 29 ml/beat (mean 11 +/- 6.2), peak regurgitant volumes from 1.0 to 8.1 liters/min (mean 3.5 +/- 2.1) and regurgitant fractions from 8.0% to 54% (mean 29 +/- 12%). Twenty-two of 24 jets were eccentric. Simple linear regression analysis between maximal color jet areas and peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions showed correlation, with r = 0.68 (SEE 0.64 cm2), r = 0.63 (SEE 0.67 cm2), r = 0.63 (SEE 0.67 cm2) and r = 0.58 (SEE 0.71 cm2), respectively. Univariate regression comparing regurgitant jet area with cardiac output, stroke volume, systolic left ventricular pressure, pressure gradient, left ventricular/left atrial pressure gradient, left atrial mean pressure, left atrial v wave pressure, systemic vascular resistance and maximal jet velocity showed poor correlation (0.08 < r < 0.53, SEE > 0.76 cm2). CONCLUSIONS: This study demonstrates that color Doppler jet area has limited use for evaluating the severity of mitral regurgitation with eccentric jets.     

MR guidance of laser disc decompression: preliminary in vivo experience

BACKGROUND: The mechanism of atrial natriuretic peptide (ANP) release has been difficult to demonstrate in patient studies because of inaccuracies in measuring atrial volumes using conventional techniques. METHODS: Magnetic resonance imaging was performed in 28 clinically stable patients (New York Heart Association class 3) with chronic heart failure to determine right atrial (RA), left atrial (LA), and ventricular volumes. In addition, right heart catheterization was serially performed and plasma ANP levels (in picograms per milliliter) were drawn from the right atrium. RESULTS: Five patients had to be excluded from data analysis for technical reasons. The remaining 23 patients had the following hemodynamic measurements (mean +/- SD): RA mean pressure 7+/-5 mm Hg, pulmonary artery mean pressure 28+/-10, pulmonary capillary wedge pressure 21+/-8 mm Hg, and cardiac index 2.9+/-1.4 (L/min/m2), respectively. Plasma ANP levels were significantly elevated at 162+/-117 (normal range 20 to 65 pg/ml, p < 0.05), as were LA and RA volumes compared with healthy controls (RA volume 128+/-64 ml vs 82+/-25 ml, p < 0.05; LA volume 157+/-54 ml vs 71+/-24 ml, p < 0.01, respectively). ANP showed a stronger relation with atrial volumes (RA volume, r = 0.91, p = 0.0001; LA volume, r = 0.80, p = 0.001) than with atrial pressures (RA mean pressure, r = 0.45, p = 0.03; pulmonary capillary wedge pressure, r = 0.67, p = 0.001). A subgroup analysis of patients with increased RA or LA volumes (>1 SD of mean of controls) revealed a stronger relation between ANP and RA volumes than between ANP and LA volumes. CONCLUSIONS: These data suggest that increased right heart volume with subsequent increased atrial stretch is the major determinant for ANP release in patients with stable CHF.     

Hemodynamic and physiologic changes during support with an implantable left ventricular assist device

To evaluate hemodynamic effectiveness and physiologic changes on the HeartMate 1000 IP left ventricular assist device (Thermo Cardiosystems, Inc., Woburn, Mass.), we studied 25 patients undergoing bridge to heart transplantation (35 to 63 years old, mean 50 years). All were receiving inotropic agents before left ventricular assist device implantation, 21 (84%) were supported with a balloon pump, and 7 (28%) were supported by extracorporeal membrane oxygenation. Six patients died, primarily of right ventricular dysfunction and multiple organ failure. Nineteen (76%) were rehabilitated, received a donor heart, and were discharged (100% survival after transplantation). Pretransplantation duration of support averaged 76 days (22 to 153 days). No thromboembolic events occurred in more than 1500 patient-days of support with only antiplatelet medications. Significant hemodynamic improvement was measured (before implantation to before explantation) in cardiac index (1.7 +/- 0.3 to 3.1 +/- 0.8 L/min per square meter; p < 0.001), left atrial pressure (23.7 +/- 7 to 9 +/- 7.5 mm Hg; p < 0.001), pulmonary artery pressure, pulmonary vascular resistance, and right ventricular volumes and ejection fraction. Both creatinine and blood urea nitrogen levels were significantly higher before implantation in patients who died while receiving support. Renal and liver function returned to normal before transplantation. We conclude that support with the HeartMate device improved hemodynamic and subsystem function before transplantation. Long-term support with the HeartMate device has a low risk of thromboemboli and makes a clinical trial of a portable HeartMate device a realistic alternative to medical therapy.     

Asynchronous volume changes of the two ventricles after Fontan operation in patients with a biventricular heart

Coordinated contraction of the ventricle is an important determinant of pump function, which seems to be particularly important in Fontan circulation with one pumping ventricle. We analyzed the synchronism of contraction of the two ventricles in 11 patients with a biventricular heart who had undergone Fontan operation. Curves representing ventricular volume changes in a cardiac cycle measured on angiograms were smoothed and divided into 20 segments. We calculated the number of segments of the same directional volume changes (synchronous changes) between the two ventricles (synchronous ratio). We also calculated the total volume of the two ventricles (the two as one whole ventricle) by adding their volumes in each segment and calculated the ratio (stroke volume ratio) of the aortic stroke volume from the whole ventricle to the sum of stroke volumes of the morphological right and left ventricles. If the two ventricles ejected the blood in a completely synchronous manner, these ratios should be 1.0. In seven patients with synchronous ratios of 0.75 or greater and a stroke volume ratio of greater than 0.95, the cardiac index was 3.2 +/- 0.3 l/min/m2, the maximum total volume (corresponding to end-diastolic volume) was 106 +/- 45% normal, and the ejection fraction was 0.44 +/- 0.10. In four patients with ratios of less than 0.70 and 0.95, respectively, the parameters were 2.4 +/- 0.5 (P < 0.05), 193 +/- 92%, and 0.33 +/- 0.08, respectively. The synchronous ratio was inversely correlated with cardiac output. In conclusion, synchronism of the cardiac cycle of the two ventricles affects Fontan circulation in patients with a biventricular heart.     

A rare cause of respiratory failure: Echinococcus of the pulmonary artery

To combine the advantages of the standard technique and the bicaval technique of orthotopic heart transplantation, we use a muscular flap of recipient heart right atrium for connecting the superior vena cava with the donor heart right atrium. The results in respect to the maintenance of atrioventricular valve competence as well as atrial conduction are promising.     

Monetary compensation for plasma donors: a record of safety

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia after open heart surgery. Traditional treatment with a range of antiarrhythmic drugs and electrical cardioversion is associated with considerable side effects. The aim of this study was to examine the feasibility and efficacy of low-energy atrial defibrillation with temporary epicardial defibrillation wire electrodes. METHODS AND RESULTS: Epicardial defibrillation wire electrodes were placed at the left and right atria during open heart surgery in 100 consecutive patients (age 65+/-9 years; male to female ratio 67:23). Electrophysiological studies performed postoperatively revealed a test shock (0.3 J) impedance of 96+/-12 omega (monophasic) and 97+/-13 omega (biphasic). During their hospital stay, AF occurred in 23 patients (23%) at 2.1+/-1.3 days postoperatively. Internal atrial defibrillation was performed in 20 patients. Of these patients, 80% (16/20) were successfully cardioverted with a mean energy of 5.2+/-3 J. Early recurrence of AF (< or =60 seconds after defibrillation) developed in 8 patients. Five patients had multiple episodes of AF. In total, 35 episodes of AF were treated, with an 88% success rate. Only 6 patients (30%) required sedation. No complications were observed with shock application or with lead extraction. CONCLUSIONS: Atrial defibrillation with temporary epicardial wire electrodes can be performed safely and effectively in patients after cardiac operations. The shock energy required to restore sinus rhythm is low. Thus, patients can be cardioverted without anesthesia.     

Right ventricular function in orthotopic total atrioventricular heart transplantation

BACKGROUND: Total orthotopic heart transplantation was recently introduced into clinical practice as an alternative technique of orthotopic heart transplantation, adding bicaval and left and right pulmonary vein anastomoses to pulmonary artery and ascending aorta connection (total technique). The conventional technique (ventricular transplantation with atrioplasty) is compared with the total technique with particular emphasis on right ventricular performance. METHODS: Forty-eight mongrel dogs (23 to 31 kg) were used for 12 total and 12 standard orthotopic heart transplantations. Right ventricular (RV) function and atrial systole were analyzed with the use of micromanometry, sonomicrometry, and ultrasonic flow probes (preload-independent RV recruitable stroke work, RVPRSW). Fourier analysis was used to calculate RV power and pulmonary vascular impedance. RESULTS: There was no significant difference in cardiac ischemic and bypass times between the two groups. After transplantation, sinus rhythm was preserved after all total transplantations and after only one standard transplantation; no significant hemodynamic differences were observed. RVPRSW in the total group was conserved after transplantation; however, RVPRSW decreased by 39% (+/-8, p < .05) in the standard group. There was also a significant decrease in the rate of RV filling in the standard group after transplantation, suggesting decreased right atrial function. Pulmonary vascular impedance and RV power output were not significantly different after transplantation between the two groups. CONCLUSIONS: Total atrioventricular transplantation is a feasible alternative and conserves normal sinus rhythm. Ischemic and bypass times were not significantly different when the superior vena cava anastomosis is performed last after the release of the aortic cross-clamp. The insignificant decrease in the rate of RV filling with the use of the total technique suggests conserved RV diastolic function after transplantation with less decreased RV function in the total group.     

Chronic alcohol intake reduces retinoic acid concentration and enhances AP-1 (c-Jun and c-Fos) expression in rat liver

OBJECTIVES: In vivo studies of the human coronary resistance circulation cannot control for indirect effects of myocardial metabolism, compression, and neurohumoral influences. This study directly examined the vasodilator responses of the human coronary microcirculation to both receptor-dependent and -independent agonists. METHODS: Atrial arterioles were dissected from human right atrial appendage (103 +/- 2 microns diameter, n = 185 vessels from 145 patients) obtained at the time of cardiopulmonary bypass and left ventricular vessels from explanted human hearts (148 +/- 10 microns diameter, n = 57 vessels from 18 patients). After dissection, vessels were mounted onto pipettes in Kreb's buffer under conditions of zero flow and at a constant distending pressure of 60 mmHg. Drugs were applied extraluminally and steady state changes in diameter measured with videomicroscopy. RESULTS: After contraction by endothelin or spontaneous tone, increasing concentrations of adenosine diphosphate (ADP) produced a similar dose-dependent dilation in vessels from atria (maximum 89 +/- 4%, n = 76) and ventricles (maximum 74 +/- 9%, n = 10). The dilation to ADP was abolished by mechanical removal of the endothelium. Similar dilator responses were found to bradykinin, substance P, arachidonic acid, and the calcium ionophore A23187 in both atria and ventricle. In contrast, acetylcholine (ACh) constricted all atrial vessels (-58 +/- 3%, n = 63) regardless of patient age or underlying disease. This constriction was attenuated by denudation, but not affected by inhibition of nitric oxide synthase or cyclo-oxygenase. Microvessels isolated from human ventricle exhibited a heterogeneous response to ACh with dilation being the predominant response. CONCLUSIONS: We conclude that isolated human coronary arterioles demonstrate endothelium-dependent dilation. However, the response to acetylcholine is unique with vasoconstriction in atrial vessels and dilation in ventricular arterioles.     

Value of right ventricular ejection fraction in predicting short-term prognosis of patients with severe chronic heart failure

BACKGROUND: The prognosis of chronic heart failure has been studied extensively, but factors predicting short-term outcome in patients with severe chronic heart failure are still poorly defined, and the current indications for heart transplantation as a treatment for end-stage heart failure need on objective analysis. METHODS: Purpose of the study was to identify the determinants of short-term prognosis in a group of 142 consecutive ambulatory patients (mean age 49.8 +/- 11 years). Referred for heart transplantation because of severe chronic heart failure, the patients were admitted with left ventricular ejection fraction markedly depressed and had had symptoms in spite of an optimal standardized medical therapy for at least 1 month. Baseline clinical and instrumental evaluation included right-sided heart catheterization with a flow-directed multilumen thermodilution catheter, which enables determination of pressures, cardiac output, right ventricular volumes, and ejection fraction. RESULTS: Most patients were in New York Heart Association class III (61%) and IV (24%), and the hemodynamic profile was characterized by mean left ventricular ejection fraction of 20.2% +/- 6%, cardiac index of 2.13 +/- 0.6 l/min/m2, pulmonary capillary wedge pressure of 23.1 +/- 11 mm Hg, right atrial pressure of 7.9 +/- 6 mm Hg, right ventricular ejection fraction of 23.2% +/- 12.4%. During a mean follow-up of 11.1 +/- 9.4 months, 33 patients underwent transplantation (23.4%), 41 died (28.8%), and 68 were still alive (47.8%). There was a substantial overlap in left ventricular ejection fraction between patients divided on the basis of outcome, whereas right ventricular ejection fraction was significantly lower in patients who died or underwent transplantation. Cox multivariate analysis showed three independent prognostic variables: cause (p = 0.03), heart failure score (p = 0.001), and right ventricular ejection fraction (p = 0.000). Short-term survival (10 months) was significantly (p = 0.000) different in patients with > or = 24% or < 24% right ventricular ejection fraction. Statistical analysis identified right ventricular ejection fraction as the single variable to be highly correlated with an increased risk of early death. CONCLUSIONS: This study suggests that right ventricular function is a crucial determinant of short-term prognosis in severe chronic heart failure. Statistical analysis identified right ventricular ejection fraction, determined by thermodilution during right-sided heart catheterization, as the single most important predictor of short-term prognosis in a large cohort of patients who had symptoms in spite of a standardized, optimized, multipharmacologic treatment. The variable allows a useful risk stratification in patients with severe chronic heart failure and uniformly depressed left ventricular ejection fraction and provides guidance in the assessment of indications and timing for transplantation.     

Intermediate-term outcome of mitral reconstruction in cardiomyopathy

OBJECTIVE: Severe mitral regurgitation is a frequent complication of end-stage cardiomyopathy that contributes to heart failure and predicts a poor survival. We studied the intermediate-term outcome of mitral reconstruction in 48 patients who had cardiomyopathy with severe mitral regurgitation and were operated on between June 1993 and June 1997. METHODS: Ages ranged from 33 to 79 years (63 +/- 6 years) with left ventricular ejection fractions of 8% to 25% (16% +/- 3%). All patients were receiving maximal drug therapy and were in New York Heart Association class III-IV with severe, refractory 4+ mitral regurgitation. Operatively, all 48 had undersized flexible annuloplasty rings inserted, 7 had coronary bypass grafts for incidental disease, 11 had prior bypass grafts, and 11 also had tricuspid valve repair. RESULTS: One operative death occurred as a result of right ventricular failure. Postoperative transesophageal echocardiography revealed mild mitral regurgitation in 7 patients and no mitral regurgitation in 41. There were 10 late deaths, 2 to 47 months after mitral reconstruction. The 1- and 2-year actuarial survivals have been 82% and 71%. At a mean follow-up of 22 months, the number of hospitalizations for heart failure has decreased, and 1 patient has had heart transplantation. Significantly, New York Heart Association class improved from 3.9 +/- 0.3 before the operation to 2.0 +/- 0.6 after the operation. Twenty-four months after the operation, left ventricular volume and sphericity have decreased, whereas ejection fraction and cardiac output have increased. CONCLUSION: Whether this favorable modification of left ventricular function and geometry will persist remains unknown. However, mitral repair for cardiomyopathy with mitral regurgitation allows new strategies for these patients.     

Evaluation of a pulsatile pediatric ventricular assist device in an acute right heart failure model

BACKGROUND: The development of pulsatile ventricular assist devices for children has been limited mainly by size constraints. The purpose of this study was to evaluate the MEDOS trileaflet-valved, pulsatile, pediatric right ventricular assist device (stroke volume = 9 mL) in a neonatal lamb model of acute right ventricular failure. METHODS: Right ventricular failure was induced in ten 3-week-old lambs (8.6 kg) by right ventriculotomy and disruption of the tricuspid valve. Control group 1 (n = 5) had no mechanical support whereas experimental group 2 (n = 5) had right ventricular assist device support for 6 hours. The following hemodynamic parameters were measured in all animals: heart rate and right atrial, pulmonary arterial, left atrial, and systemic arterial pressures. Cardiac output was measured by an electromagnetic flow probe placed on the pulmonary artery. RESULTS: All results are expressed as mean +/- standard deviation and analyzed by Student's t test. A p value less than 0.05 was considered statistically significant. Base-line measurements were not significantly different between groups and included systemic arterial pressure, 80.6 +/- 12.7 mm Hg; right atrial pressure, 4.6 +/- 1.6 mm Hg; mean pulmonary arterial pressure, 15.6 +/- 4.2 mm Hg; left atrial pressure, 4.8 +/- 0.8 mm Hg; and cardiac output, 1.4 +/- 0.2 L/min. Right ventricular injury produced hemodynamics compatible with right ventricular failure in both groups: mean systemic arterial pressure, 38.8 +/- 10.4 mm Hg; right atrial pressure, 16.8 +/- 2.3 mm Hg; left atrial pressure, 1.4 +/- 0.5 mm Hg; and cardiac output, 0.6 +/- 0.1 L/min. All group 1 animals died at a mean of 71.4 +/- 9.4 minutes after the operation. All group 2 animals survived the duration of study. Hemodynamic parameters were recorded at 2, 4, and 6 hours on and off pump, and were significantly improved at all time points: mean systemic arterial pressure, 68.0 +/- 13.0 mm Hg; right atrial pressure, 8.2 +/- 2.3 mm Hg; left atrial pressure, 6.4 +/- 2.1 mm Hg; and cardiac output, 1.0 +/- 0.2 L/min. CONCLUSIONS: The results demonstrate the successful creation of a right ventricular failure model and its salvage by a miniaturized, pulsatile right ventricular assist device. The small size of this device makes its use possible even in small neonates.     

Atrial septal pacing: a method for pacing both atria simultaneously

By pacing both atria simultaneously, one could reliably predict and optimize left-sided AV timing without concern for IACT. With synchronous depolarization of the atria, reentrant arrhythmias might be suppressed. We studied four male patients (73 +/- 3 years) with paroxysmal atrial fibrillation and symptomatic bradyarrhythmias using TEE and fluoroscopy as guides; a standard active fixation screw-in lead (Medtronic model #4058) was attached to the interatrial septum and a standard tined lead was placed in the ventricle. The generators were Medtronic model 7960. The baseline ECG was compared to the paced ECG and the conduction time were measured to the high right atrium, distal coronary sinus and atrial septum in normal sinus rhythm, atrial septal pacing, and AAT pacing. On the surface ECG, no acceleration or delay in AV conduction was noted during AAI pacing from the interatrial septum as compared with normal sinus rhythm. The mean interatrial conduction time for all 4 patients was 106 +/- 2 ms; the interatrial conduction time measured during AAT pacing utilizing the atrial septal pacing lead was 97 +/- 4 ms (P = NS). During atrial septal pacing, the mean conduction time to the high right atrium was 53 +/- 2 ms. The mean conduction time to the lateral left atrium during atrial septal pacing, was likewise 53 +/- 2 ms. We conclude that it is possible to pace both atria simultaneously from a single site using a standard active fixation lead guided by TEE and fluoroscopy. Such a pacing system allows accurate timing of the left-sided AV delay.     

Angiotensin II receptor type 1 mRNA is upregulated in atria of patients with end-stage heart failure

There is increasing evidence that pathological changes in the myocardium during chronic heart failure (CHF) are partly regulated through the activation of the renin-angiotensin system (RAS), an effect mediated by the angiotensin II type 1 receptor (AT1R). We examined the expression of cardiac AT1R mRNA in normal (atria, n=7; ventricle, n=3) and end-stage CHF human hearts (atria, n=8; ventricle, n=14). Tissue was snap-frozen immediately after explantation during orthotopic cardiac transplantation; control specimens were obtained from healthy donor hearts rejected for technical reasons. Northern blots of purified total mRNA from each tissue were hybridized with a random primed radiolabeled probe for the coding sequence of AT1R. Stringent conditions were used for both hybridization (5X SSC, 65 degrees C) and washing (0.5X SSC, 0.1% SDS, 65 degrees C) of the membrane. Left and right atrial tissue showed low levels of AT1R mRNA expression in the controls, with statistically significant upregulation of expression in tissue from pathological hearts; CHF atria 1.28+/-0.86 optical density (OD) units, control atria 0.56+/-0.31 OD units, P=0.05 (mean+/-s.d.). There were undetectable levels in ventricles from either control (2/2) or dilated hearts (7/7). The results were independent of the etiology of the heart failure and suggest that increased levels of atrial AT1R mRNA may occur in response to elevated atrial pressures in heart failure.     

Electrophysiologic properties and response to pharmacologic agents of fibers from diseased human atria

We used standard microelectrode techniques to record action potentials of human right atrial fibers obtained during cardiac surgery, and correlated these potentials with clinical and preoperative ECG data. Human atrial fibers were classified as follows: Group A (ten patients) had a maximum diastolic potential (MDP) of -71.4 +/- 5.1mV (mean +/- SD), and action potentials that were primarily fast responses. These atria were normal or slightly dilated. In group B (12 patients) MDP was 50.3 +/- 5.7 mV; action potentials were slow responses and the atria were moderately to markedly dilated. Atrial arrhythmias occurred in four group B and no group A patients. The ECG revealed a signficant difference (P less than 0.005) in P wave duration: group A, 89 +/- 3.0 msec; group B, 111 +/- 6.0 msec. Verapamil, 0.1 mg/L, markedly depressed only the action potential plateau of group A. Procainamide 1-100 mg/L had equivalent effects on fibers of both groups A and B, effects which were small at dosages of less than 40 mg/L. Procainamide did not depress slow response automaticity, but verapamil (0.1-1 mg/L) did.     

Electrophysiological properties in patients undergoing atrial compartment operation for chronic atrial fibrillation with mitral valve disease

AIMS: Surgical treatment for atrial fibrillation is now feasible in selective cases. The aim of this study was to assess the electrophysiological properties of patients undergoing atrial compartment operation for chronic atrial fibrillation. METHODS AND RESULTS: Electrophysiological studies were performed in 20 mitral valve patients with atrial fibrillation who had been maintained in sinus rhythm for more than 1 year after atrial compartment operation. Intra-cardiac recording and programmed electrical stimulation were performed in various atrial compartments. The parameters studied included sinus node function, atrial conduction and refractoriness, atrioventricular conduction function and inducible arrhythmias if any. Intra-cardiac recordings showed that the rhythm was of sinus origin in all cases, with the earliest atrial activity located in the high right atrium. The mean sinus cycle length was 750 +/- 110 ms, AH time 106 +/- 29 ms, and HV time 53 +/- 7 ms. The sinus node function was normal in 18 patients (90%), and only two patients had prolonged sinus node recovery and sino-atrial conduction. The right atrial appendage compartment was driven by the sinus node in all patients. However, the conduction time from the high right atrium to the right atrial appendage compartment was markedly prolonged in 12 of 15 patients (80%) undergoing the three-compartment operation in which an incision was placed between the high right atrium and right atrial appendage compartments. On the other hand, the electrical activities in the left atrial compartment were much more varied. In 13 of 20 patients (65%), the left atrial compartment was driven by the sinus node; 11 of the 13 patients had a normal or mildly prolonged conduction time (ranged 75 to 146 ms), whereas two patients had a marked delay in conduction (200 ms and 266 ms, respectively). In the remaining seven patients, the left atrial compartments were dissociated from the rest of the heart; five of them had a quiescent left atrium, one a fluttering left atrial rhythm, and one a slow left atrial rhythm. The effective refractory period was longer in the left atrial compartment (242 +/- 47 ms) as compared to that of the high right atrium (224 +/- 26 ms, P < 0.01) and right atrial appendage compartments (219 +/- 25 ms, P < 0.01). Programmed electrical stimulation could not induce atrial fibrillation in any patient, whereas two patients had inducible atrial flutter and three repetitive atrial responses. CONCLUSIONS: (1) Atrial compartment operation does not impair sinus node function in most cases. (2) Elimination of atrial fibrillation while maintaining the electrical connection between different atrial compartments is feasible.     

Modulation of atrial repolarization by site of pacing in the isolated rabbit heart

BACKGROUND: Single-site or multisite atrial pacing may reduce the incidence of atrial fibrillation in humans. The therapeutic mechanisms may include synchronization of atrial repolarization (repolarization "memory") and/or decreased dispersion of atrial repolarization. These responses have not been well documented in intact atria. METHODS AND RESULTS: Monophasic action potential recordings were made from six atrial epicardial sites in 39 isolated perfused rabbit heart preparations during 3 hours of continuous right atrial, left atrial, or biatrial pacing. Action potential recordings obtained at times 0, 45, 90, 135, and 180 minutes were computer analyzed for activation time (AT) and 90% action potential duration (APD) at each site. No consistent relationship could be demonstrated between APD and AT at any time during atrial pacing (all P > .05). On average, left atrial APDs were longer than right atrial APDs by up to 6.3 ms at all times, regardless of the site of pacing (P < or = .05). At all times, dispersion of atrial repolarization was minimized by left atrial pacing compared with right atrial pacing (21.6 +/- 9.1 versus 32.4 +/- 15.1 ms, respectively, at time 0; P < .05). Biatrial pacing provided no further reduction in dispersion of repolarization compared with left atrial pacing (all P > .05). CONCLUSIONS: No relationship can be demonstrated between atrial AT and APD in the isolated rabbit heart preparation. This differs from ventricular repolarization "memory," which is demonstrable under the same conditions. Left atrial APD is, on average, longer than right atrial APD, suggesting spatial heterogeneity in repolarization. Dispersion of atrial repolarization is minimized by left atrial pacing in this preparation with no further advantage to biatrial pacing.