The Mirizzi syndrome: multidisciplinary management promotes optimal outcomes.

The Mirizzi syndrome (MS) is a rare cause of obstructive jaundice produced by the impaction of a gallstone either in the cystic duct or in the gallbladder, resulting in stenosis of the extrahepatic bile duct and, in severe cases, direct cholecystocholedochal fistula formation. Sixteen patients were treated for MS in our center over the 12-year period 1993--2005 for a prevalence of 0.35% of all cholecystectomies performed. One patient was diagnosed only at the time of cholecystectomy. The other 15 patients presented with laboratory and imaging findings consistent with choledocholithiasis and underwent preoperative endoscopic retrograde cholangiopancreatography, which established the diagnosis in all but one patient. All patients underwent cholecystectomy. An initial laparoscopic approach was attempted in 14 patients, of whom 11 were converted to open procedures. MS was recognized operatively in 15 patients with definitive stone extraction and relief of obstruction in 13 patients. T-tubes were placed in 10 patients and 1 patient required a choledochoduodenostomy. Two patients required postoperative laser lithotripsy via a T-tube tract to clear their stones; and in another patient, MS was detected and treated via postoperative endoscopic retrograde cholangiopancreatography (ERCP). MS remains a serious diagnostic and therapeutic challenge for endoscopists and biliary surgeons.

Electrical techniques for stimulation of the phrenic nerve to pace the diaphragm: inductive coupling and battery powered total implant in asynchronous and demand modes.

A review of the electrical design of a rf inductively coupled phrenic nerve stimulator for the diaphragm developed in our laboratories will be discussed. Modifications of the original circuit are based on long-term laboratory and clinical studies. A total implant battery powered stimulator was designed exclusively for animal studies to evaluate the effects of several stimulating parameters on diaphragm fatigue and neuromuscular structure. On the basis of these studies the optimum current level, stimulus frequency, respiratory rate, electrode configuration, and waveform were selected for clinical use to pace the diaphragm. A multiprogrammable dual output stimulator responsive to interrogation has been constructed and used in the experimental laboratory in anticipation of clinical application. There was an insignificant difference between the effect on neural structure or diaphragm function of stimulation with pulse width modulated constant voltage or with amplitude-modulated constant current. Demand pacing: maintenance of normal PACO2 by monitoring ET PACO2 with feedback to the diaphragm pacemaker to adjust the pacing rate has been successful in the experimental animal.

Fundamental considerations in pacing of the diaphragm for chronic ventilatory insufficiency: a multi-center study.

Records were reviewed of 477 patients who had diaphragm pacemakers implanted for treatment of chronic hypoventilation. Three groups were established for comparison. (1) Center group: 165 patients operated on in six medical centers participating in a cooperative study; (2) Noncenter group, sufficient data available: 203 patients operated on by surgeons with experience limited to a few cases; (3) Nonstudy group, minimal data available: 109 patients operated on as in group 2; vital statistics only were contributed. The protocol for data gathering was comprised of 154 major variables. Basic data on age, sex, diagnosis and etiology were analyzed for homogenicity of data among the groups. A comprehensive analysis of the pacing methods, complication and results from the Center group yielded information on the early experience with diaphragm pacing important to its future application.

The evolution of the treatment of isolated pulmonary valve stenosis.

In the course of studies covering 40 years, 1913 to 1953, leading to the development of cardiopulmonary bypass, many ingenious blind instrumental or digital intrusions were made into the heart chambers to treat lesions therein. Limits were defined for the arrest of circulation through part or all of the heart to permit a brief glimpse of the lesion and effect at least a partial correction. The often remarkably good results of operations performed under less than ideal operating conditions for lesions such as isolated pulmonary stenosis encouraged the interventional cardiologist and radiologist, working together, to adapt the cardiac catheter, used previously for exploration of the vascular system and diagnosing intravascular lesions, to therapeutic purposes. They positioned a catheter with uninflated balloon attached in the pulmonary artery, then either by inflating the balloon beyond the constricted orifice and pulling it through or by rapidly and precisely inflating the balloon lying across the orifice were able to disrupt the stricture and relieve the stenosis. Results matched those of early non-visual operations. Recently the cardiologist has expanded the approach to relieve other constricted orifices in the heart and great vessels and to close abnormal openings. In isolated pulmonary stenosis, the nearly complete relief of obstruction and the tolerance of the circulation to blunt disruption of valvular stenosis bodies well for the long-term success of balloon valvuloplasty in this congenital malformation of the heart.

Diaphragm pacing by electrical stimulation of the phrenic nerve.

Sophisticated techniques for electrical stimulation of excitable tissue to treat neuromuscular disorders rationally have been developed over the past 3 decades. A historical review shows that electricity has been applied to the phrenic nerves to activate the diaphragm for some 200 years. Of the contemporary methods for stimulating the phrenic nerve in cases of ventilatory insufficiency, the authors prefer stimulation of the phrenic nerve in the thorax using a platinum ribbon electrode placed behind the nerve and an attached subcutaneously implanted radiofrequency (RF) receiver inductively coupled to an external RF transmitter. Instructions are given for implanting the electrode-receiver assembly, emphasizing atraumatic handling of the phrenic nerve and strict aseptic techniques. Diaphragm pacing is conducted with low frequency electrical stimulation at a slow repetition (respiratory) rate to condition the diaphragm muscle against fatigue and maintain it fatigue-free. Candidates for diaphragm pacing are those with ventilatory insufficiency due to malfunction of the respiratory control center or interruption of the upper motor neurons of the phrenic nerve. In the Yale series, there were 77 patients treated by diaphragm pacing; 63 (82%) started before 1981 and thus were available for follow-up for at least 5 years; 33 (52%) were paced for 5 to 10 years, and 15 (24%) were paced for 10 to 16. Long term stimulation of the phrenic nerves to pace the diaphragm is an effective method of ventilatory support in selected cases.

Management of recalcitrant bronchopleural fistulas with muscle flap obliteration.

Use of muscle flap obliteration for bronchopleural fistulas appears to be indicated with (1) failure of a previous thoracoplasty, (2) anticipated failure of a thoracoplasty alone, and (3) the need to obviate a formal debilitating thoracoplasty. With the use of well-vascularized muscle flaps to fully obliterate the densely scarred cavities associated with persistent bronchopleural fistulas, we may hope to see improved healing in the bronchial stump and, in cases of residual infection, better resistance of the flap to necrosis, as well as improved delivery of chemotherapeutic agents to the local tissues. These factors may confer improved cure rates for bronchopleural fistulas similar to those seen in lower extremity salvage surgery for osteomyelitis following the introduction of vascularized pedicle and free muscle flaps. In this article we have described the versatility of the island pedicle latissimus dorsi muscle flap for closure of recalcitrant bronchopleural fistulas and associated empyema cavities. Utilizing either the dominant thoracodorsal or the minor paraspinal pedicle(s), it can reach any intrathoracic cavity by means of the appropriate thoracotomy incision.

Ventilatory support by pacing of the conditioned diaphragm in quadriplegia.

We provided full-time ventilatory support in five patients with respiratory paralysis accompanying quadriplegia by continuous electrical pacing of both hemidiaphragms simultaneously for 11 to 33 months through the application to the phrenic nerves of a low-frequency stimulus. The strength and endurance of the diaphragm muscle increased with pacing. Biopsy specimens taken from two patients who had uninterrupted stimulation for 6 and 16 weeks showed changes suggestive of the development of fatigue-resistant muscle fibers. When we compared these results with those of our earlier experience with intermittent unilateral stimulation of the diaphragm in 17 patients with respiratory paralysis, we found that continuous bilateral pacing using low-frequency stimulation appeared to be superior because of more efficient ventilation of both lungs, fewer total coulombs required to effect the same ventilation, and absence of myopathic changes in the diaphragm muscle. For patients with respiratory paralysis and intact phrenic nerves, continuous simultaneous pacing of both hemidiaphragms with low-frequency stimulation and a slow respiratory rate is a satisfactory method of providing full-time ventilatory support.

Response of the diaphragm muscle to electrical stimulation of the phrenic nerve. A histochemical and ultrastructural study.

The histological, histochemical, and ultrastructural features of canine diaphragms subjected to pacing by high-frequency electrical stimulation (27 to 33 Hz) of the phrenic nerve are compared with unstimulated diaphragms and with diaphragms subjected to pacing by low-frequency stimulation (11 to 13 Hz). The high-frequency group showed a reduced tidal volume (fatigue) after long-term stimulation, and myopathic changes which included enlarged internal and sarcolemmal nuclei, ring fibers, moth-eaten fibers with irregular histochemical staining, core/targetoid fibers, and smearing and aggregation of Z-band material with electron microscopy. The low-frequency group did not develop a significant degree of fatigue or pathological changes, and showed histochemical evidence of transformation to fast-twitch (type II) fibers. Possible pathogenic mechanisms and their similarity to those in certain human neuromuscular diseases are discussed. The application of the findings resulting from high- and low-frequency stimulation to long-term diaphragm pacing in humans with chronic ventilatory insufficiency is also discussed.

Light and electron microscopic studies of phrenic nerves after long-term electrical stimulation.

Light and electron microscopic evaluation were carried out on canine phrenic nerves subjected to long-term electrical stimulation. A total of 34 stimulated and 19 control nerves were studied by light microscopy, and 10 stimulated and five control nerves were evaluated by electron microscopy. Except in a few cases in which a higher current was used, the current used for stimulation was between 1 and 2 mA. The pulse width was 150 microseconds. The typical charge per pulse was 0.22 microC and charge density per pulse 1.125 microC/sq cm of real area. The total number of days of electrical stimulation in individual phrenic nerves ranged from 4 to 374. No morphological changes in the phrenic nerve that could be attributed to the electrical stimulation were observed by light or electron microscopic study. There were, however, two phrenic nerves cuffed with bipolar electrodes which showed focal demyelination at the electrode level, but these changes were caused by factors other than the electrical stimulation. The results of the studies have direct clinical implications to long-term stimulation of phrenic nerves.

Factors affecting performance and thromboembolism after porcine xenograft cardiac valve replacement.

Long-term durability and the need for anticoagulation in conjunction with the use of porcine valves remain questionable. We analyzed valve dysfunction and thromboembolism in 325 adult (older than 20 years) and 31 pediatric survivors who received 407 porcine xenograft valves from June, 1974, to September, 1980 (46% of all valve replacements). Valves at risk in the adults were 216 aortic, 138 mitral, and 22 tricuspid; in children, 14 aortic, eight mitral, seven pulmonary, and two tricuspid. Mean follow-up was 38 (9 to 85) months. Twenty-seven valved conduits also were followed up for 9 to 85 (mean 52) months. Two late deaths in children resulted from dysfunction and another from endocarditis. One late death in an adult was caused by embolism. The other 36 deaths in the entire group were not valve related. Dysfunction requiring reoperation at 12 to 37 months occurred in eight of 325 adults (six mitral, one aortic, and one tricuspid). Dysfunction was due to recurrent endocarditis in six and to primary tissue failure in two (both older than 35 years of age); all survived reoperation. However, in children, severe dysfunction due to primary tissue failure occurred in seven (23%) cardiac valves, necessitating replacement at 21 to 48 months, and three of 27 conduits had to be replaced at 39 to 70 months. Thromboembolism occurred in six adults with mitral xenografts but none with aortic or tricuspid valve. Four of the patients with thromboemboli (one of whom died) were among 16 who had atrial fibrillation and no warfarin, but aspirin and persantine (11.7%/patient-year) and two were among 14 with sinus rhythm on no medication. No thromboembolism occurred in patients with mitral xenografts who were in sinus rhythm and receiving antiplatelet agents or in those with atrial fibrillation receiving warfarin. This experience indicates a high incidence of relatively early failure of porcine xenograft cardiac valves in children and young adults but excellent medium and long-term performance in older adults, in whom severe dysfunction occurred mainly with recurrent endocarditis. Thromboembolism occurred primarily in patients with mitral replacement especially with atrial fibrillation and no anticoagulants.

The lymphatic system. Some surgical considerations.

This article on the lymphatics was undertaken for three reasons: The first is to recount the story of the rediscovery of these vessels in the 17th century and briefly review the subsequent events leading up to our present knowledge of the lymphatic system. The second is to emphasize the role of the lymphatics in maintaining extracellular fluid balance, in the removal of protein, fat, and other substances of large molecular size from the tissue spaces, and in the circulation of the lymphocytes from their germinal centers and storage depots to all parts of the body via lymphaticovenous connections. The third reason is to suggest that the responsibility for maintaining the transport function of the lymphatics properly belongs to the vascular surgeon.