Risks and benefits of combined maze procedure for atrial fibrillation associated with organic heart disease.

OBJECTIVES: This study sought to identify the risks and benefits of adding the maze procedure in patients with atrial fibrillation (AF) undergoing operation for underlying organic cardiac disorders. BACKGROUND: Persistent AF often leaves patients symptomatic even after otherwise successful cardiac surgery. METHODS: Fifty-one patients undergoing valvular operation and the maze procedure (n = 43) or repair of congenital anomalies (n = 8) combined with the maze procedure were compared with 51 patients (control group) matched for underlying diseases and procedures except for the maze operation. Each group, including 31 patients with a concomitant tricuspid annuloplasty and 12 undergoing reoperation, were similar in age, duration of arrhythmia, degree of cardiomegaly and New York Heart Association functional class. RESULTS: Patients undergoing the maze procedure had longer cardiopulmonary bypass time (213 vs. 144 min, p < 0.0001), longer cardiac arrest (134 vs. 93 min, p < 0.0001) and greater blood loss with longer respiratory care (39 vs. 18 h p = 0.021) and intensive care unit stay but no mortality. No significant differences were found in catecholamine or transfusion requirements immediately after operation. Sustained AF was much less frequent in the maze group (12% at 1 year) than the control group (86%, p < 0.0001), with an average follow-up period of 32 months (range 25 to 42). Atrial contraction was documented in 41 (80%) and 40 (78%) patients for right and left ventricular filling, respectively, after the maze procedure, resulting in a significantly smaller cardiac size and improved functional capacity. Medication was discontinued in seven patients in the maze group compared with two in the control group. CONCLUSIONS: Improved restoration of atrial rhythm and contraction with combined maze operation appeared to justify the increased operative time and complexity and postoperative care.

Single lung transplantation in rats with fatal pulmonary hypertension.

Effects of single lung transplantation on fatal pulmonary hypertension were evaluated in rats receiving a lethal dose of monocrotaline. Inbred rats treated with monocrotaline (80 mg/kg) received a left lung isograft at 4 weeks (n = 9) and at 6 weeks (n = 6), when moderate and severe pulmonary hypertension, respectively, had developed. Medicated (n = 12) and nonmedicated rats (n = 12) served as control animals. Each rat was tested weekly with treadmill for exercise tolerance and oxygen consumption during a 10-week period after medication and after they were killed. Medicated control rats lost exercise tolerance and highest oxygen consumption per unit time consistently to the range of resting value (or 45% of nonmedicated control rats), and all died from severe pulmonary vascular occlusive disease with right ventricular hypertrophy before 10 weeks (right ventricular/left ventricular weight ratio of 1.16). All rats receiving a left lung isograft at 4 weeks survived and regained highest oxygen consumption per unit time (87% of nonmedicated control rats), with the lung transplant receiving 65% (nonmedicated control rats, 39%) of cardiac output and milder right ventricular hypertrophy (right ventricular/left ventricular weight ratio of 0.46). Except for one, all rats that received a left lung isograft at 6 weeks tolerated single lung transplantation, but they died soon after reperfusion because of pulmonary edema in the graft that received 58% of cardiac output with right ventricular/left ventricular weight ratio of 0.79. Results of single lung transplantation in rats were dependent on severity of pulmonary hypertension. In rats with moderate pulmonary hypertension, single lung transplantation was successful in reversing exercise intolerance and right ventricular hypertrophy. Single lung transplantation was unsuccessful when pulmonary hypertension was severe in the rat model because increased flow toward the lung transplant resulted in graft pulmonary edema.

Single lung transplantation in rats with chemically induced pulmonary hypertension.

Physiologic effects of single lung transplantation on pulmonary hypertension were studied in rats with monocrotaline-induced pulmonary hypertension. Inbred rats treated with monocrotaline (40 mg/kg) received a left lung isograft from a normal donor 2 weeks later, when pulmonary hypertension became significant (transplant group; n = 6). These rats and control rats treated with monocrotaline (mediated control group; n = 11) or vehicle alone (normal control group; n = 9) were followed up weekly by metabolic treadmill testing for exercise tolerance and oxygen consumption up to 6 weeks after monocrotaline (4 weeks after transplantation), when all rats underwent hemodynamic and histologic examinations. Whereas maximal oxygen consumption and exercise tolerance consistently deteriorated in the medicated control group of rats, indices in the transplant group stopped deteriorating 2 weeks after lung transplantation and remained at levels similar to those of normal control rats. Severe pulmonary hypertension (68 +/- 19 mm Hg) and right ventricular hypertrophy (right ventricular/left ventricular weight ratio, 0.95 +/- 0.19) were confirmed in medicated control rats in contrast to transplant animals, in which these two indices remained at normal control levels. Whereas left-to-right lung perfusion ratio was constant among rats not receiving transplants (0.69 +/- 0.16), it was significantly elevated (2.27 +/- 0.65; p less than 0.001) in those receiving transplants, suggesting preferential flow through the lung isograft. The results suggest that, in the early phase of pulmonary hypertension, single lung transplantation shifts pulmonary perfusion to the grafted lung, avoiding right ventricular pressure overload and thereby preserving exercise tolerance at a nearly normal level in rats with monocrotaline-induced pulmonary hypertension.

Right-to-left interatrial shunt in rats with progressive pulmonary hypertension.

A right-to-left interatrial shunt may prolong survival in patients with pulmonary hypertension presumably because of decompression of the right side of the heart. To test this hypothesis, 74 rats with monocrotaline-induced pulmonary hypertension were followed up weekly with cardiopulmonary exercise testing with a metabolic treadmill system for exercise tolerance, heart rate, oxygen uptake, carbon dioxide production, and survival until subsequent or induced death 8 weeks after monocrotaline treatment. In rats with an interatrial shunt, oxygen uptake and carbon dioxide production were higher and survival was better (n = 22, 27%) than those in rats without a shunt (n = 52, 0%; p < 0.05). For the prospective assessment of the effects of a reversed shunt, 24 other rats underwent a left superior vena cava-to-left atrial appendage anastomosis as a functional interatrial shunt (atrial septal defect group) 4 weeks after monocrotaline treatment when severe pulmonary hypertension had developed and were compared with an additional 25 rats receiving a sham operation. Both groups had exercise capacity depressed to the resting levels by 2 weeks after operation. Although transcutaneous oxygen levels decreased in response to exercise in the atrial septal defect group, uptake and carbon dioxide production stayed higher than those in the sham operation group with significantly better survival 4 weeks after operation (atrial septal defect 30% versus sham operation, 0%; p < 0.05), at which time a reversed shunt was determined with systemic embolization of intravenously infused microspheres. A right-to-left interatrial shunt, anatomic or functional, preserved basal metabolism and prolonged survival in rats with progressive pulmonary hypertension.

Cox maze procedure for chronic atrial fibrillation associated with mitral valve disease.

Between April 1992 and October 1993, we combined a modified maze procedure with mitral valve repair (n = 26) or replacement (n = 36) in 62 patients with atrial fibrillation, including 16 patients undergoing reoperation. Associated procedures included aortic valve operation (n = 22), tricuspid annuloplasty (n = 28), atrial plication (n = 10), and others (n = 3). Duration of atrial fibrillation varied from 0.1 to 23 years (average 8.3 +/- 6.4 years), the f-wave voltage ranged from 0 to 0.45 mV (0.16 +/- 0.09 mV), and cardiothoracic ratio varied from 46% to 85% (64% +/- 9%). We modified the maze atriotomies to preserve the sinus node artery and used cryoablation to simplify procedures. Aortic crossclamp time was 142 +/- 25 minutes and cardiopulmonary bypass time 226 +/- 34 minutes. No early or late deaths occurred in a total of 783 patient-months of follow-up. In 52 patients (84%) who regained atrial rhythm, an atrial A-wave was detected in 84% for transtricuspid flow and in 71% for transmitral flow. One patient with sinus rhythm had an episode of transient neurologic ischemia 4 months after mechanical valve implantation. The 10 patients who remained in atrial fibrillation had preoperative fibrillation for a significantly longer time than the rest of the patients with atrial rhythm (14.8 versus 7.2 years p < 0.001) and a larger left atrial dimension (70 versus 58 mm, p < 0.01). Nonetheless, no variable alone could have predicted postoperative rhythm for individual patients. The results suggest that the maze procedure is safe and effective and therefore should be considered for patients with chronic atrial fibrillation undergoing mitral valve operations.

Monocrotaline-induced pulmonary vascular disease after contralateral lung transplantation in the rat.

To test a hypothesis that reduction in pulmonary perfusion pressure and flow affect underlying vascular disease, pulmonary pathology was studied in monocrotaline-treated rats undergoing single lung transplantation. Inbred rats were treated with 40 mg/kg (group T1, n = 6) and 80 mg/kg of monocrotaline (group T2, n = 9), received a left lung isograft 2 and 4 weeks after medication, and were killed 4 and 6 weeks after single lung transplantation, respectively. For each group, rats receiving the same amount of monocrotaline (M1, M2) or vehicle (N1, N2) served as controls. Monocrotaline-treated rats developed pulmonary vascular disease and right heart failure, resulting in severe exercise intolerance in M1 or death in M2 unless single lung transplantation had been carried out. At death, pulmonary blood flow was directed toward the left lung isograft, and the retained right lung received a significantly reduced fraction of cardiac output. Right to left ventricular weight ratio was significantly reduced in both groups as compared to the respective control rats, suggesting reduced perfusion pressure. Although thickness of media in small pulmonary arteries (media/radius) was normal (34% +/- 4%) in the lung isografts, it was significantly increased in the contralateral lung (group T1, 45% +/- 5%; group T2, 48% +/- 3%), which was not significantly different from that of monocrotaline-treated control rats, respectively (group M1, 47% +/- 7%; group M2, 49% +/- 6%). Although single lung transplantation reduced perfusion pressure and flow toward the monocrotaline-treated native lung, it failed to affect vascular morphology significantly.

Afferent reinnervation after lung transplantation in the rat.

Denervation at lung transplantation results in loss of cough reflex and attenuated local defense mechanisms, accounting for increased incidence and severity of infection after lung transplantation. We studied the presence or absence of spontaneous afferent reinnervation in rats at various intervals after orthotopic left pulmonary isografting (n = 52). Normal rats (n = 21) and rats undergoing left hilar stripping (n = 14) served as control subjects. Afferent reinnervation was tested physiologically by reflex bradycardia in response to intravenous infusion of capsaicin (30 microg/kg), an extract of paprika stimulating pulmonary C-fibers. Injection of capsaicin was repeated before and after right pulmonary artery occlusion to divert all pulmonary blood flow to the left lung or isograft. Whereas rats early after surgical denervation lost the reflex after right pulmonary artery occlusion, rats examined 8 months or longer after surgery showed potent reflex bradycardia in response to capsaicin, as did the control rats. Immunohistochemical staining for sensory neuron-specific substances, such as calcitonin gene-related peptide and substance P, were identified only in the right native lung and left pulmonary isografts 2 months or longer after transplantation. Fluorogold was found only in the ipsilateral nodose ganglion after left lung intrapleural injection of the neuron-specific tracer in rats 8 months or longer after denervation. These experiments provide physiological, morphologic, and neurologic evidence suggesting that afferent lung innervation, abolished early after transplantation, is spontaneously reestablished and functioning in the ipsilateral vagus nerve by 8 months after pulmonary isografting in the rat.

Long-term results of entry closure and aneurysmal wall plication with axillofemoral bypass: a new procedure for repair of DeBakey type 3 dissecting aneurysm.

To prevent aneurysm rupture, avoid pseudoaneurysm formation, and preserve intercostal arteries, a new procedure for repair of DeBakey type 3 dissecting aneurysm was developed. Since January 1977, 28 patients have undergone repair of type 3 dissecting aneurysm. Fifteen patients with type 3b underwent this new procedure (group 1) and 13 patients with type 3a dissecting aneurysm underwent segmental graft replacement (group 2). In group 1 a permanent axillofemoral bypass was placed on the right side. Next the intrathoracic false lumen was opened longitudinally, the entry was closed, and the aneurysmal wall was sutured around the true lumen as tightly as possible. The operative mortality rate was 20% in group 1 and 31% in group 2. One of 15 patients in group 1 died of operation-related causes, whereas three patients in group 2 died. There were six late deaths: three in group 1 and three in group 2. Paraplegia occurred in neither group 1 nor group 2. The mean diameter of the plicated descending aorta was 24.0 +/- 2.7 mm 3 months after surgery. No recurrence was detected in group 1. These results suggested that this new surgical technique for repair of type 3 dissection reduces the incidence of paraplegia and pseudoaneurysm formation.

Preoperative risk analysis in patients receiving Jarvik-7 artificial heart as a bridge to transplantation.

To distinguish high-risk patients prior to implantation of a Jarvik-7 artificial heart as a bridge to transplantation, our 37 attempts were reviewed retrospectively. Arbitrary scores of 1 to 4 were given for nine preoperative factors on the basis of results obtained by uni- and multivariate analyses between successful cases and failed attempts; transplant rejection (scored 4: S4) or postoperative heart failure (S3) as the indication, recipient height less than 175 cm (S3), body surface area less than 1.8 m2 (S3), hyperbilirubinemia greater than 24 microM/l (S2), preoperative renal failure requiring dialysis (S2), weight less than 60 kg (S2), and age greater than 40 years (S1). All except one of the 16 patients with successful bridge had a total score of less than 4, with an average score of 1.3 in contrast to 6.6 in the 21 failed cases (p less than 0.001). Among the 17 patients who scored less than 4, 15 received transplants (specificity 90%), while only one qualified for transplantation among 20 patients who scored 4 or more (sensitivity 94%). The two unpredicted failures resulted from mediastinitis and pulmonary infarction, both attributable to postoperative management. Multiple preoperative factors in combination could have successfully predicted the outcome of mechanical support in our experience. These results underscore the importance of patient selection to achieve successful and effective use of the Jarvik-7 as a bridge to heart transplantation.

Right lung transplantation followed by left pneumonectomy in the rat.

OBJECTIVE: To develop a rodent lung transplant model which depends on graft function for survival, total microsutureless lung transplantation was carried out and followed by contralateral native pneumonectomy in the rat. METHODS: Total non-microsuture right lung transplantation was undertaken using a cuff technique with anastomotic areas twice as big as those for the left lung transplantation. Inbred rats received either right (n = 10) or left lung isograft (n = 10) with non-microsuture techniques and underwent contralateral native pneumonectomy 2 weeks later to test the function of the grafted lung. RESULTS: While none of the left lung recipients could be disconnected from the respirator after right pneumonectomy, eight of ten right lung recipients tolerated left pneumonectomy, increased body weight and regained exercise capacity (oxygen uptake 49 +/- 4 ml/kg per min) comparable to that of control rats undergoing right hilar stripping and left pneumonectomy. CONCLUSIONS: The results suggest that the grafted right lung, but not the left lung, allows survival, growth and exercise of the recipient. Right lung transplantation followed by native left pneumonectomy may serve as a physiologic model of lung transplantation in the rat.

Surgical stratification of patients with atrial fibrillation secondary to organic cardiac lesions.

BACKGROUND: While the maze procedure does not always eliminate atrial fibrillation (AF) secondary to organic cardiac lesions, concomitant performance of the procedure is associated with increased surgical complexity and potential risks. METHODS: To stratify the surgical approach for patients with AF secondary to underlying cardiac lesions, we analyzed 24 preoperative and perioperative variables in 115 consecutive patients with AF undergoing a modified maze procedure combined with valvular intervention (101), repair of congenital anomalies (13) and coronary revascularization (1). RESULTS: Patients who remained in AF (18) compared to patients with restored atrial rhythm (97), had a higher incidence of giant left atrium (56% vs 10%, P < 0.0001), larger cardiothoracic ratio (70 +/- 13 vs 62 +/- 8%, P = 0.001) and left atrial dimension (64 +/- 12 vs 55 +/- 12 mm, P = 0.004), a longer history of AF (13.7 +/- 6.8 vs 8.3 +/- 6.9 years, P = 0.003) and lower f-wave voltage (0.10 vs 0.15 mV, P = 0.004). Multivariate logistic regression analysis of 24 preoperative and perioperative variables identified the presence of giant left atrium, cardiothoracic ratio and age at operation as the significant risk factors predisposing patients to persistent postoperative AF. Retrospective estimation identified 73 (63.5%) patients with a high probability of atrial defibrillation (97.3%) and 42 (36.5%) patients with a high risk of failure (38.1%). Regardless of the preoperative risk analysis or the performance of left atrial plication, every patient with a postoperative left atrial dimension less than 40 mm or cardiothoracic ratio below 55% was successfully defibrillated. CONCLUSION: The results suggest performing the maze procedure before "risk factors" develop for patients with predicted maze-amenable AF. While omitting the maze procedure may be prudent for patients with suspected maze-refractory AF, the simultaneous reduction of left atrial size may offset the increased risk from preoperative size factors. A prospective study seems warranted to examine the effects of left atrial plication on postoperative rhythm.

Two-week, but not 1-week, hypoxic exposure enhances nitric oxide-mediated basal tone regulation in rat resistance pulmonary arteries.

We measured internal diameter (ID) changes in resistance and conduit pulmonary arteries of 1- and 2-week hypoxic rats and normoxic control rats in response to nitric oxide synthase (NOS) inhibitors in vivo. At 2 weeks of hypoxic exposure, the ID reduction as a result of NOS inhibition was enhanced within the resistance arteries, but not at 1 week of hypoxia.

Delayed diagnosis of a glenohumeral joint dislocation in a child with developmental delay.

Glenohumeral joint dislocations rarely occur in children. Those that have been reported have all been reduced in a closed fashion. With the exception of one, there have not been any comorbidities in the children that would have led to a delay in diagnosis. To the best of our knowledge, we report the first case of a child with a delayed diagnosis of an anterior dislocation of the glenohumeral joint that required an open reduction. In a child with other medical problems, especially developmental delay, who may have difficulty expressing his symptoms, early detection and intervention are crucial and may obviate the need for open reduction of the dislocated and painful glenohumeral joint.

Partial left ventriculectomy. The First Japanese Registry Report 1999.

OBJECTIVE: Partial left ventriculectomy has been performed without standardized inclusion/exclusion criteria. A registry has been established to accumulate experience with this procedure to identify indications, risks and benefits. METHODS: In response to a mailed inquiry, 90 cases were voluntarily registered from 28 Japanese institutions. RESULTS: Males (n = 67, 74.4%) predominated, and 29 (32.2%) patients were over 60 years old. The underlying cardiac pathologies included dilated cardiomyopathy (n = 75, 83.3%), valvular disease (n = 8, 8.9%), the dilated phase of hypertrophic cardiomyopathy (n = 4, 4.5%), and others (n = 3, 3.3%). Gender, age, etiology, papillary muscle excision and absent transplant indication did not significantly affect survival. Poorer preoperative condition, reduced contraction and decompensation necessitating emergency operation were each associated with a significantly higher risk. Hospitals performing less than 5 cases had poorer results than more experienced institutions (p = .0019), which showed a tendency towards improved survival in the second half of their experience (p = .096). Hospital mortality (n = 29, 32.6%) and late death (n = 10, 11.2%) were mainly from ventricular failure with few sudden deaths over a period of 63.6 patient years follow-up. Late mortality was equally distributed in the first year and leveled off with significantly improved cardiac functional class in survivors. CONCLUSION: Partial left ventriculectomy was associated with better survival in less symptomatic patients with better contractile reserve undergoing an elective operation preserving the papillary muscles. Avoidance of identified risk factors may allow better patient selection and improved survival in the current environment where rescue transplantation is not readily available. Long-term follow-up is warranted with more registry data.

Successful reversal of pulmonary hypertension in Eisenmenger complex.

We present a case of a 19-year old female with systemic pulmonary artery (PA) pressure due to a congenital ventricular septal defect (VSD) and atrial septal defect (ASD). She was pink at rest and cyanotic on exercise. Lung biopsy revealed grade IV pulmonary vascular changes. As a preliminary step PA was banded to increase right-to-left shunt and decrease aortic (Ao) saturation with consequent decrease in PA saturation. After one year, when she was no longer cyanotic, even on exercise, lung biopsy revealed total regression of pulmonary vascular changes. As a definitive procedure VSD and ASD were closed and PA was debanded. Cardiac catheterization one week postoperatively showed PA pressure to be 50% of systemic pressure. We postulate that reversal of pulmonary vascular changes were due to lowered PA saturation. We further believe that lower PA pressure could have contributed to this regression of pulmonary vascular changes. We performed the same procedure in six more patients with similar positive clinical response. This new concept brings renewed hope to many children who otherwise are candidates for heart lung transplantation.

Supramolecular ferric porphyrins and a cyclodextrin dimer as antidotes for cyanide poisoning.

OBJECTIVES: This study aimed to evaluate the antidotal effect of a newly developed supramolecular complex, ferric porphyrins and a cyclodextrin dimer (Fe(III)PIm3CD), that possess a higher binding constant and quicker binding rate to cyanide ions than those of hydroxocobalamin (OHCbl) in the presence of serum protein. METHODS: First, in vitro cytochrome activity and cell viability were evaluated in murine fibroblast cells cultured with various doses of Fe(III)PIm3CD and potassium cyanide (KCN). Next, BALB/c mice were pretreated with intravenous OHCbl (0.23 mmol/kg), Fe(III)PIm3CD (0.23 mmol/kg), or saline and then received KCN (lethal dose 100% (LD100): 0.23 mmol/kg) through a stomach tube. Finally, as a resuscitation model, KCN-induced apnea was treated with a bolus injection of an equimolar dose of antidotes followed by a slow infusion of the same reagent. RESULTS: Fe(III)PIm3CD showed dose-dependent antidotal effects in vitro. Pretreatment with Fe(III) PIm3CD prevented KCN-induced apnea significantly better than OHCbl. Resuscitation with Fe(III)PIm3CD resulted in an earlier resumption of respiration than that seen with OHCbl. However, 24-h survival was similar among the treatments (Fe(III)PIm3CD, nine of nine mice; OHCbl, eight of nine mice). CONCLUSION: Fe(III)PIm3CD exerted significant antidotal effects on cyanide toxicity in vitro and in vivo, with a potency equal in the mortality of cyanide-poisoned mice or superior in the respiratory status during an acute phase to those of OHCbl.