Computed tomography assessment of lung volume changes after bronchial valve treatment.

The aim of the present study was to correlate clinical outcome measures following treatment with bronchial valves with regional lung volume. Computed tomography (CT) scan data from 57 subjects with severe emphysema were obtained from nine North American clinical trial sites. IBV(R) Valves (Spiration, Inc., Redmond, WA, USA) were placed to occlude segmental and subsegmental bronchi in right and left upper lobes using a flexible bronchoscope. Subjects completed a St George's Respiratory Questionnaire (SGRQ), pulmonary function test (PFT) and exercise capacity test. CT scans were analysed at baseline and at 1, 3 or 6 months after treatment to measure total and lobar lung density, volume and mass. Total lung volumes measured using CT were strongly correlated with PFT and did not change with treatment. However, the treated upper lobes significantly decreased in volume in 88% of the observations, by mean+/-sd 335+/-444 mL, or a decrease of 10.2% in the 6 month data. The untreated lobes had an 11.6% increase in volume. Changes in regional lung volume were associated with clinically meaningful improvements in SGRQ (-8.95+/-16.22), but not clinically meaningful PFT changes. The significant health status improvements reported by subjects following bilateral bronchial valve treatment are associated with regional lung volume changes and interlobar shift measured using computed tomography.

Surgical correction in infancy to reduce mortality in transposition of the great arteries.

The mortality for infants with transposition of the great arteries (TGA) prior to the introduction of medical and surgical septostomy was over 80% by 6 months of age. The mortality has fallen recently, due to balloon atrial septostomy (BAS), but still exceeds 25% by 6 months of age in major centers. The cumulative mortality rises to 40% by 1 year of age with or without additional surgical atrial septectomy. In our center, 12 patients with an average age of 3 months were operated on for interatrial baffle correction of their TGA under surface-induced deep hypothermia. BAS had been done preliminarily in those patients without an adequate atrial communication. Ten of these 12 patients (83%) survived. These patients have been followed up from one month to eight years with an average follow-up of over four years. Surgical correction during infancy offers a better survival rate for infants with TGA than does medical management, with or without palliative surgery.

Determination of cardiac output by thermodilution during hypothermia.

The thermodilution method for estimating cardiac output was compared with the electromagnetic flowmeter technique in 10 mongrel dogs at normothermia and during surface-induced deep hypothermia. Thermodilution curves obtained during cooling or rewarming must be corrected for the baseline drift caused by changing core temperature. At normothermia, the correlation coefficient between the two methods was 0.96 and the reproducibility of the thermodilution technique was 5 percent. Comparable correlation was present during hypothermia. Curves corrected for baseline drift resulted in significantly different output values from those derived from uncorrected curves (p < 0.05). The thermodilution method is valid at low body temperatures. Clinical confirmation of these results, particularly during open heart surgery in infants, is warranted.

Use of athrombogenic tubing for perfusion rewarming following surface-induced deep hypothermia.

A method of heparinless, oxygenatorless, left heart bypass perfusion rewarming following surface hypothermia, with the use of a closed circuit with 130 ml. prime volume including heat exchanger, has been devised. The use of polyurethane-polyvinyl-graphite (PPG)-coated tubing has previously been reported. In this text, the use of an athrombogenic coating with cetyl-pyridinium chloride (CPC) as a regional heparin carrier was studied in dogs, comparing groups with PPG tubing and total systemic heparinization or plain polyvinyl tubing without systemic heparinization. Heparin compounded in the CPC coating eluted into the blood and caused mild transient whole-body heparinization during rewarming from 20 degrees to 25 degrees C., as evidenced by prolongation of the thrombin time. Alterations of hematologic parameters in all three groups were similar to those during surface rewarming except for those affected by heparinization. The left heart bypass method was found useful for hypothermic open-heart surgery when utilized with an athrombogenic surface coating or total body heparinization. It was concluded that the CPC coating is superior to the PPG coating since no cracking surface develops, it is translucent, and it provides a more effective athrombogenic surface.

Internodal conduction. Immediate and long-term effects of transverse circular incision of right atrium including atrial septum.

Immediate and long-term effects of a transverse circular incision of the entire right atrium, including the atrial septum, on internodal conduction were studied in 7 dogs. Electrocardiograms were followed up to 35 weeks, and the atrial epicardial excitation sequence was evaluated in all 7 dogs. The findings were compared with data from 3 normal dogs and 3 other dogs which underwent total atrial transverse incisions. All dogs with total atrial separation developed complete atrioventricular (A-V) block immediately after the operation and died within 3 days. All dogs with right atrial interruption exhibited persistent sinus rhythm with slight extension of P-R intervals and a normal QRS immediately after the operation. The mean P-R interval reached its maximum at the fourth day (50 per cent increase), remained prolonged through the first week, but returned to near control valves after 12 weeks. Three days later developed transient arrhythmia; sinus arrhythmia; sinus arrhythmia in 2 dogs and second-degree block in 1 appeared between the tenth and fourteenth postoperative days. Postoperative P vectors migrated toward the left. Atrial excitation sequence studies demonstrated prolongation of atrial epicardial conduction intervals (2.3 times) between the sinus node and distal right atrial wall. The presence of an interatrial conduction mechanism (whether by specific pathways or not), through which sinus node excitation was transmitted to the A-V node was demonstrated.

Current practice of coronary artery bypass surgery. Results of a national survey.

A survey of techniques used in coronary artery bypass graft (CABG) surgery by 400 experienced cardiac surgeons is presented. These surgeons performed 41,000 CABG operations in 1975. A seventy-question survey form was answered by each surgeon on their techniques for cardiopulmonary bypass and myocardial preservation, choice of bypass conduit, and grafting techniques. We found that extracorporeal circulation is almost always used in CABG surgery. A wide divergence of practice exists in the use of left ventricular vents and in methods of myocardial protection during coronary artery grafting. A spectrum of graft suture techniques is employed, the most common being a running double-ended suture anastomosis with the end of the vein initially fixed only at its heel to the coronary artery. Only 23 surgeons (6 per cent) prefer the internal mammary artery (IMA) rather than saphenous vein, when feasible, as the bypass conduit of choice for CABG surgery.

Heparinless, oxygenatorless perfusion rewarming following surface-induced deep hypothermia for open-heart surgery.

To facilitate perfusion rewarming without the use of total body heparinization or an oxygenator following open-heart correction with surface hypothermia, we divised a pump circuit. The circuit, totally primed with 100 c.c. of saline, consists of polyurethane-polyvinyl-graphite (PPG) coated Tygon tubes (with one end tapered by heat treatment) and a copper-coil heat exchanger. A roller pump was used to achieve partial bypass from the left atrium to the ascending aorta with flow rates up to 70 c.c. per kilogram per minute. Experiments in dogs resulted in rapid rewarming, immediate return of cardiac function, and hematologic alterations similar to those noted during surface rewarming. The safety of the method was also demonstrated. Prothrombin time, partial thromboplastin time, and platelet values returned to control levels upon rewarming, and no thromboemboli or bleeding problems were noted. Six clinical experiences were accumulated. Details of the method, hematologic and blood chemical analyses in dogs, and the first clinical trial in a 3-month-old infant with transposition of the great vessels are reported.

Fibrinogen Seattle: a qualitatively abnormal fibrinogen in a patient with tetralogy of Fallot.

A dysfibrinogen was detected in the plasma of a 14-year-old asymptomatic Caucasian boy who had tetralogy of Fallot. The mutant molecular species could be traced through four generations in an autosomal dominant type of inheritance pattern. Nine of 14 family members were found to have the coagulopathy. Following laboratory and clinical evaluation, the proband underwent radical repair of the cardiac defect without incident. This variant is tentatively designated fibrinogen Seattle pending further characterization.

Prefabricated Dacron baffle for use in correction of transposition of the great arteries.

Interatrial venous transposition for correction of transposition of the great arteries (TGA) is facilitated by using a premolded Dacron baffle. Fine-mesh Dacron is easily fashioned to the desired shape in a metallic brass mold at 200 degrees C. The resultant baffle material can be autoclaved without losing its shape or altering the fabric characteristics of flexibility and porosity. This premolded baffle has been used in our last 7 patients with TGA over the past two years without complication, and the use of Dacron in 13 survivors over the past seven years has shown no pulmonary or venous obstructions related to the material.

Simplified technique for pericardial patch of the right ventricular outflow tract.

Pericardial patching to enlarge the right ventricular outflow tract is often required in congenital cardiac surgery in lesions such as tetralogy of Fallot, pulmonary atresia, pulmonary stenosis, and pulmonary artery repair following removal of a palliative pulmonary artery band. A method of simplifying the attachment of the pericardial patch onto the right ventricular outflow tract is described.

Improved anesthesia for deep surface-induced hypothermia: the halothane-diethyl ether azeotrope.

The halothane-diethyl ether azeotrope was evaluated in dogs as the anesthetic agent for deep surface hypothermia with total circulatory arrest for open-heart operation. All 10 animals given azeotrope in 100% oxygen (O2) experienced atrial arrhythmias during cooling, and 1 had ventricular fibrillation prior to the completion of cooling at 18 degrees to 20 degrees C. After only 30 minutes' arrest, 8 of the 10 dogs had postoperative motor disturbances. Administering the azeotrope in 95% O2 and 5% carbon dioxide (CO2) yielded markedly improved results characterized by a rapid, smooth cooling course, easy resuscitation following circulatory arrest, and rapid rewarming, and 3 out of 10 dogs experienced mild motor disturbance after 60 minutes of circulatory arrest. This method, when compared with our standard method of ether in 100% O2, resulted in reduced blood lactates and a striking improvement in clinical status on the first postoperative morning. In limited clinical trials, infants undergoing repair of congenital cardiac defects have done well and responded as expected based on the laboratory experience. Since the results with the azeotrope in 95% O2 and 5% CO2 were at least as good as, and in several instances better than, those with the standard method employing either, the nonexplosive characteristic of the azeotrope warrants continued evaluation of this agent.

Circulatory dynamics during surface-induced hypothermia under halothane-ether azeotrope anesthesia.

Circulatory dynamics during surface- induced deep hypothermia using the halothane-diethyl ether azeotrope in 100% oxygen (O2) without circulatory arrest and 95% O2 and 5% carbon dioxide (CO2) with and without 60 minutes of arrest were evaluated in 15 adult mongrel dogs. Mean arterial pressure was lower in animals given 5% CO2 than in animals given 100% O2 during cooling. Cardiac output in the 5% CO2 groups increased until 30 degrees C cooling and then gradually decreased to 29% of control at 20 degrees C. Cardiac output in the 100% O2 group progressively decreased to 16% of control at 20 degrees C cooling and was 51 to 77% of the output in the 5% CO2 animals at comparable temperatures throughout the hypothermia procedure. The differences in cardiac output were attributed primarily to changes in stroke volume since heart rates were not significantly different. These changes were probably secondary to differences in systemic vascular resistance, which had increased sixfold in the animals given 100% O2 and had only doubled in the 5% CO2 groups at 20 degrees C during cooling. Hemodynamic variables in animals given 5% CO2 did not reveal significant differences in arrested versus nonarrested animals during early rewarming. However, with further warming, cardiac output, stroke volume, left ventricular stroke work, and mean pulmonary arterial and pulmonary artery wedge pressures were lower, and systemic and pulmonary vascular resistances were higher in the arrest group. We conclude that the improved results with halothane-diethyl ether azeotrope in 95% O2 and 5% CO2 during surface hypothermia are due to a greater cardiac output and reduced peripheral vascular resistance.

Oxygen consumption during surface-induced deep hypothermia under halothane anesthesia.

The effect of halothane-100% oxygen anesthesia on oxygen consumption was studied in 10 dogs subjected to surface-induced deep hypothermia with 30 minutes of circulatory arrest. The results were compared with previous oxygen consumtion data under ether-100% oxygen anesthesia. Low cardiac output, especially during the rewarming period, low PaO2, and a large arteriovenous oxygen difference during rewarming were significantly different in the halothane group, despite identical oxygen consumption in both groups. These differences could not elucidate the exact cause of postoperative motor disturbances associated with 30 minutes of circulatory arrest in the halothane group. The possibility that there was higher oxygen consumption under halothane anesthesia is discussed.

Patch closure of aortic annulus mycotic aneurysms.

Twenty-three patients with bacterial endocarditis and mycotic aneurysms of the aortic annulus were treated between 1978 and 1985. There were 18 men and 5 women ranging from 24 to 72 years old. All patients had congestive heart failure and positive blood cultures as a complication of the endocarditis and were in New York Heart Association (NYHA) Functional Class III or IV. The aneurysm complicated late prosthetic valve endocarditis in 7 patients and native valve endocarditis in 16. The most common infecting organisms were streptococci (12 patients) and staphylococci (7 patients). The noncoronary sinus was the most frequent site for aneurysm formation. Following debridement of the abscess cavity, the orifice of the aneurysm was closed with a patch of Dacron in 20 patients and autologous pericardium in 3. A prosthetic valve (18 bioprosthetic and 5 mechanical) was secured to the noninfected portion of the native annulus and to the patch at the level of annulus. There were 3 deaths, 1 perioperative and 2 late, each without evidence of residual infection or aortic insufficiency. There are 20 late survivors (87%). After a mean follow-up of 1 year, all patients are in NYHA Functional Class I. Patch closure of mycotic aneurysms involving the aortic annulus permits aggressive debridement of the abscess cavity and affords closure of the orifice without tension. The prosthetic valve can be seated at the level of the native annulus, thus avoiding complicated reconstructive procedures of the aortic root and coronary arteries. This technique is an effective alternative in selected cases of mycotic aneurysms involving the aortic annulus.

Boerhaave syndrome. Successful conservative management in three patients with late presentation.

Three patients with Boerhaave syndrome were successfully managed with nonoperative treatment. The diagnosis was delayed 5 days in one patient and 10 days in the other two. None of the patients appeared septic. Their conditions had been misdiagnosed as myocardial infarction, pneumonia and pulmonary embolism. Treatment consisted of intravenous hyperalimentation and administration of antacids and antibiotics. Cimetidine was also used in one patient. Two patients were discharged 14 days after diagnosis and the third on the 20th hospital day. Follow-up barium swallows showed complete healing in 2 months in all three patients. Conservative management of spontaneous esophageal perforation is feasible when (1) the perforation is already 5 days old, (2) there are no signs of severe sepsis, (3) esophageal barium study shows a wide-mouthed cavity draining freely back into the esophagus, and (4) the pleural space is not contaminated. When the diagnosis is made promptly, surgical therapy remains the treatment of choice, and patients managed conservatively who show signs of sepsis should be operated on without hesitation. Follow-up esophageal evaluation should be performed to confirm complete healing and to evaluate underlying disease.

Outcome analysis of surgical therapy for patients with angina pectoris.

Surgical therapy for coronary artery disease results in improved survival rates for selected groups of patients, particularly those with left ventricular dysfunction and/or severe coronary artery disease as evidenced by involvement of two or more vessels. Successful augmentation of coronary blood flow as shown by patient saphenous vein graft is associated with improved exercise tolerance when compared with patients in whom the grafts are occluded. Patients with impaired left centricular function as a result of their coronary artery disease appear to experience an improvement in this function with the augmentation of coronary blood flow by patent saphenous vein bypass grafts. In patients with occluded grafts and impaired left ventricular function, the left ventricular function is unchanged. Ptients with normal left ventricular function who sustain occlusion of their grafts will probably experience a reduction in their systolic ejection fraction.

The significance of colloid osmotic pressure during induced hypothermia.

Colloid osmotic pressure (COP) during hypothermia with and without total circulatory arrest was evaluated in 20 adult mongrel dogs (average body weight = 18.6 kg). All animals were surface-cooled to 20 degrees C (rectal temperature) under halothane-diethyl ether azeotrope anesthesia and divided into 4 equal groups. In Groups I (non-arrest) and II (60 minute-arrest) 10% low molecular weight dextran (LMWD; 1 gm/kg = 10 ml/kg) was administered during cooling. Physiological saline (10 ml/kg) was given in Groups III (non-arrest) and IV (60 minute-arrest) during cooling. COP in LMWD groups increased significantly during cooling and was consistently higher than it was in the saline groups during rewarming. There were no significant differences in heart rate (HR), mean arterial pressure (MAP), central venous (CVP) and pulmonary artery wedge pressures (PAW) between the 4 groups during cooling. The increase in hematocrit (Hct) in animals that received saline was significant at the end of cooling and during rewarming. Hct was not significantly changed in Group I throughout the procedure, whereas in Group II (60 minute-arrest) it increased significantly during rewarming despite the administration of LMWD. Rewarming time in Group II was significantly shorter than in Group IV (144.2 +/- 9.6 min vs 193.2 +/- 32.6 min, respectively). We conclude that the administration of LMWD effectively reduces hemoconcentration and is also beneficial for maintaining better peripheral circulation.

Prolongation of the safe interval of hypothermic circulatory arrest: 90 minutes.

Twenty-nine adult mongrel dogs were subjected to profound hypothermia and 90 minutes of total circulatory arrest. Pure surface (Group I) hypothermia and combined surface/perfusion techniques with bubble (Group II) and membrane (Group III) oxygenator systems were employed. Circulation was arrested at average esophageal temperatures of 18.4 degrees, 11.9 degrees and 8.5 degrees C in Groups I, II and III, respectively. Three animals in Group I failed to resuscitate. All survivors in the pure surface series developed postoperative gait (hypermetria) disturbances. One intraoperative death occurred in Group II and four of eight dogs arrested at esophageal temperatures above 10 degrees C but less than 15 degrees C developed motor disturbances during a three week neurologic evaluation period. Animals arrested below 10 degrees C (esophageal) did not display postoperative neurological abnormalities. Three dogs in Group III died from a hemorrhagic diathesis of uncertain etiology. None of the survivors (5) that were cooled and arrested below esophageal temperatures of 10 degrees C developed motor or sensory disturbances. We conclude that in the canine model the central nervous system can be protected for 90 minutes of total circulatory arrest at esophageal temperatures less than 10 degrees C.

The importance of appropriate concentrations of inspired carbon dioxide on induced hypothermia under halothane-ether azeotrope anesthesia.

Thirty adult mongrel dogs were divided into 3 equal groups and studied to define the optimal PCO2 level with azeotrope (halothane-diethyl ether) anesthesia under surface hypothermia (Groups I, II and III = F1CO2 0%, 5% and 10%, respectively). All animals were cooled to 18-20 degrees C and were subjected to 30 (Group I) or 60 minutes (Groups II and III) of total circulatory arrest. Group I animals had frequent arrhythmic episodes during cooling and postoperative motor disturbances occurred in 80% despite only 30 minutes of circulatory arrest. By contrast Group II animals were less arrhythmic during cooling; were easily resuscitated following 60 minutes of arrest and only 30% developed moderate reversible motor disturbances postoperatively. Hemodynamics were similar between Groups II and III during cooling but resuscitation using an F1CO2 of 10% (Group III) was extremely difficult and required massive cardiotonic support throughout rewarming. Furthermore, two dogs in Group III died within the first two postoperative days. However, none of the 8 survivors displayed neurological abnormalities. On balance, a ventilatory regimen utilizing 5% CO2 during surface-induced hypothermia under azeotrope anesthesia resulted in optimum intraoperative management and a satisfactory postoperative course and although some CNS disturbance (high-stepping gait) was noted, all animals recovered completely.