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Biomedical subjects

H Hastings

Publications and source records attributed to H Hastings.

At least 37 records · Page 2Linked to original sources
PubMed1994

Differentiation of beats of ventricular and sinus origin using a self-training neural network.

Despite advances in the computerized detection of arrhythmias, arrhythmia recognition by morphological waveform analysis still poses a difficult problem. Artificial neural networks, computer algorithms that are self-trained by an analog of biological synaptic modification to perform pattern recognition, hold great promise for the differentiation of various cardiac rhythms. The goal of this study was to differentiate beats of sinus and ventricular origin on a global basis and on a patient-specific basis by the use of artificial neural network analysis. Neural networks were trained to recognize digitized intracardiac electrograms (9 patients) and surface electrocardiograms (11 patients) obtained during sinus rhythm and ventricular tachycardia. After training, sinus rhythm or ventricular tachycardia beats were input into the neural network, and classified as to their origin. By the use of modified receiver operating characteristic curve plots, it was possible to differentiate with high sensitivity and specificity between beats of sinus origin and ventricular origin in all patients. The addition of high amounts of noise to the beats did not markedly degrade the performance of the surface ECG neural networks, and still allowed high sensitivity in differentiating beats of sinus origin from beats of ventricular origin, especially when noise was added to the training set. Neural networks provided sensitive and specific detection of cardiac electrical activity during sinus rhythm and ventricular tachycardia, and may play an important role in allowing development of improved arrhythmia recognition and management systems.

Aged↗
PubMed1994

The classification and treatment of heterotopic ossification about the elbow and forearm.

Successful treatment of HO about the forearm and elbow relies on a working understanding of the risk factors, the pathophysiology and pathoanatomy, and the potential role for reconstructive procedures. These elements must be combined with a certain degree of flexibility in the approach to patients with a wide range of individual needs. Class I HO should be managed primarily with close observation, serial radiographs, and appropriate physical therapy regimens. The temporal relationship between the insult and the appearance of HO may modify the approach. When HO is noted within the first 6 weeks, use of anti-inflammatory agents is recommended; if the patient has developed limiting ectopic bone in the past, consideration should be given to a single dose of radiotherapy. In the 6-week to 3-month period, therapy is conducted to maintain full motion and an anti-inflammatory agent continued or started. We have not observed initial HO appearance after the third month. Class IIA HO can involve the anterior or posterior aspects of the elbow joint, or both. These groups are further divided into those limited by soft tissue (muscle and capsular contracture) and those blocked by bone (coronoid extension, humeroradial, humeroulnar, blocked olecranon fossa). The anterior group limited by soft tissue is addressed by capsulotomy, releases, and lengthenings. This group requires careful neurolysis and protection of vascular structures. For anterior bony bridges, resection is combined with capsulotomy. The location of the forearm "insertion" site of the new bone dictates alternative procedures such as interposition or radial head resection. The condition of the joint is usually preserved in these cases, but arthroplasty must always be considered when injury has led to joint derangement. Posteriorly, limitations in motion are caused by a contracted scarred triceps, capsular contracture, or bony impingement and synostosis. Treatment requires posterior capsular release and triceps tenolysis. Bridging bone is excised, the olecranon partially excised, and the olecranon fossa reestablished. Attempts should be made to preserve the fat pad of the olecranon fossa, which can act as an effective interposition material. Although characterized by limited pronosupination, class IIB HO can be located in any of the six distinct anatomic sites previously outlined. Simple resection, with or without interposition, is useful for a majority of the HO that is coincident with the interosseous membrane, but the areas at the proximal and distal extent of the forearm may demand special procedures to restore motion.(ABSTRACT TRUNCATED AT 400 WORDS)

Elbow Joint↗
PubMed1993

Scapho-lunate diastasis in fractures of the distal radius. Pathomechanics and treatment options.

The concurrence of scapho-lunate diastasis and distal radial fractures is now well established. External fixation is considered to be one of the best methods of treating distal radial fractures, but in the presence of ligament injury, distraction fixation may lead to carpal instability and chronic wrist pain. We have reviewed existing English literature and analyzed possible mechanisms of injury, and offer some suggestions towards treatment of this combination of injuries.

Adult↗
PubMed1993

Distal unicondylar fractures of the proximal phalanx.

The records of 38 consecutive patients (38 fractures) who underwent treatment for distal unicondylar fractures of the proximal phalanx were reviewed to evaluate fracture characteristics, mechanism of injury, treatment options, and functional outcomes. Four classes of fracture pattern were defined radiographically. Most fractures occurred during ball sports and involved an axial splitting of extended digits, with the condyle closet to the midline of the hand fracturing most commonly. We believed that the fracture occurred as a result of tension loading due to a distraction force from the collateral ligament. All fractures healed. Follow-up examination averaged 3 years. Five of seven nondisplaced fractures treated with splinting and four of ten displaced fractures treated with reduction and single Kirschner wire fixation displaced. Fractures treated with multiple Kirschner wire fixation had the best final joint motion. Class IV fractures with a small palmar coronal fragment had the poorest final motion. A short period of post-operative immobilization did not adversely affect final proximal interphalangeal joint motion. We recommend multiple Kirschner wire or miniscrew fixation of these fractures as the most predictable method of treatment. Final proximal interphalangeal joint motion is not uniformly excellent in patients with these fractures.

Adolescent↗
PubMed1993

Preoperative factors and outcome after lunate decompression for Kienböck's disease.

Preoperative factors and outcome were studied after lunate decompression for Kienböck's disease. Twenty-three patients treated with radial shortening or scaphoid-trapezium-trapezoid fusion were evaluated. The mean follow-up was 59 months. Neither good nor excellent outcomes were found with either lunate-preserving procedure when the preoperative radioscaphoid angle was greater than 60 degrees. Outcomes in the radial shortening osteotomy group were superior to those in the group treated with scaphoid-trapezium-trapezoid fusion. Lunate collapse was not prevented by either treatment method. Lunate index, carpal height, and staging did not correlate with outcome. Measurement of radioscaphoid angle provides predictive information regarding the outcome of stage III (Decoulx/Lichtman) Kienböck's disease treated with radial shortening or scaphoid-trapezium-trapezoid fusion.

Adult↗
PubMed1993

[Arthrodesis of the wrist. Indication, technique and functional consequences for the hand and wrist].

Three studies conducted in our center demonstrated an improved technical success rate and elimination of preoperative pain in patients undergoing wrist fusions, with no significant difference in the ability to perform rapid movements requiring manual dexterity in the course of activities of daily living compared with patients who had undergone motion-preserving limited arthrodeses. The only absolute drawback of wrist fusion is that it obviously does not allow for any wrist motion at all. Limited intercarpal arthrodesis preserves some motion, but according to our results never leads to increased motion postoperatively. Several specific skills were found to present difficulty in patients who had undergone total wrist fusion. These included those requiring volar flexion in a limited space, where it would be difficult to have recourse to compensatory motion imparted by the shoulder and elbow, and those requiring forceful pronation and supination with simultaneous strong grasping. For patients involved in certain occupations requiring fine manual dexterity in tight spaces, wrist fusion might not be the most appropriate procedure. It is interesting that there appears to be a learning curve to the patient's ability to undertake specific activities postoperatively. A strong practice effect is present for the first 3-6 postoperative months, during which time a significant improvement in the patient's overall function is noted. Total wrist arthrodesis gives highly predictable results in the treatment of wrist pain and instability. The ability to perform normal activities of daily living and strenuous manual tasks was comparable to that after alternative motion-preserving procedures. We have not observed improved wrist motion after any wrist motion-preserving procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1993

Indications and techniques of open reduction. Internal fixation of distal radius fractures.

Complex distal radius fractures present in a variety of patterns that differ by the area and degree of involvement of the articular and metaphyseal fracture components. No single method of treatment is appropriate for all fractures. This article discusses the types of fractures that either require or are best handled by formal open reduction and internal or external fixation.

Bone Screws↗
PubMed1992

Martin-Gruber revisited.

A new classification system for Martin-Gruber connections is described. This comprises four types of connection that can theoretically exist and that differ by their source and destination. The world literature has been reexamined and the incidence of Martin-Gruber connections was found to be 17% overall. By the new classification, 60% are type I, sending motor branches from the median to the ulnar nerve to innervate "median" muscles; 35% are type II, sending motor branches from median to ulnar nerves to innervate "ulnar" muscles; 3% are type III, sending motor fibers from the ulnar to the median nerve to innervate "median" muscles; and 1% are type IV, sending motor fibers from the ulnar to the median nerve to innervate "ulnar" muscles.

Forearm↗
PubMed1992

Adhesions between muscle and bone after forearm fracture mimicking mild Volkmann's ischemic contracture.

Five cases of digital flexion contractures after healed forearm fractures were incorrectly diagnosed as mild Volkmann ischemic contractures. All failed to respond to conservative therapy and were considered significant enough to require surgical correction. At surgery, the involved muscle-tendon units were densely adherent to the bone and callus of the fracture site with no evidence of ischemic involvement of the muscle. Lysis of adhesions and lengthening of the contracted muscle corrected the deformities.

Adolescent↗
PubMed1990

Consequences for retinal growth when vision occurs in S2 space.

We postulate that the process of vision occurs in the S2 space. The retina is endowed with the topology of a part of a two-sphere S2, roughly, the topology of a hemisphere. There is a corresponding topology on the tectal surface, induced by the anatomy of the retino-tectal connections. Our analysis predicts the experimentally observed "near-neighbour" relationships between points in the visual field and their representation in the tectum. Further, in this context, topological arguments are presented to indicate that if the normal developing retinal disc in goldfish undergoes a process of deformation, a discontinuity is generated at the retinal surface. This discontinuity makes the differential patterns of the retinal and tectal tissues more compatible, and also enables the retina (which grows throughout the life of the animal) to conveniently connect to the tectum.

Animals↗
PubMed1990

The lateral approach for operative release of post-traumatic contracture of the elbow.

A lateral approach was used to release a post-traumatic contracture of the elbow in seven patients, and the results were evaluated an average of thirty-eight months postoperatively. Extension improved from an average flexion contracture of 45 degrees preoperatively to one of 12 degrees postoperatively, and the average point of maximum flexion increased from 116 degrees preoperatively to 129 degrees postoperatively. The average arc of motion increased 46 degrees. All patients began using a continuous-passive-motion device immediately after the operation. There were no problems with wound-healing or formation of heterotopic bone.

Adolescent↗
PubMed1988

Extravasation of phenytoin in the hand.

A case of subcutaneous phenytoin extravasation in the hand is reported. Treatment consisting of compressive dressing, elevation, and splinting was successful in restoring hand function.

Aged↗
PubMed1988

Fusion of the thumb metacarpophalangeal joint to treat posttraumatic arthritis.

Thumb metacarpophalangeal (MCP) fusion to treat posttraumatic arthritis is retrospectively reviewed in 18 patients, 16 of whom were examined and functionally tested, with an average follow-up of 18 months. All patients were satisfied. There was 100% fusion in an average of 59.9 days. Preoperative disabling MCP pain was present in all patients, and mild postoperative pain and difficulty in picking up small objects were present in 78%. Results did not depend on position of fusion or preoperative arc of MCP motion. Key pinch strength was significantly increased by fusion. Complications included four pin tract infections without sequelae and three cases of prominent tension band hardware, which were removed in two.

Adolescent↗
PubMed1988

Treatment of closed articular fractures of the metacarpophalangeal and proximal interphalangeal joints.

One hundred thirty-four closed articular fractures of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints were reviewed to identify common fracture patterns, assess results, and define the most successful methods of treatment. Articular involvement greater than 20 per cent and displacement more than 1 to 2 mm usually requires open reduction and internal fixation. Fracture involvement and displacement were better tolerated by the MCP than PIP joint. Problem fractures and treatment recommendations are discussed.

Adolescent↗
PubMed1988

Tendon transfers for ulnar nerve palsy. Evaluation of results and practical treatment considerations.

Tendon transfers for correction of clawing deformity in ulnar nerve palsy are only consistently successful in young ligamentously lax individuals. Correction of deformity is most inconsistent in the intrinsically stiff hands of older individuals. Correction of clawing is more difficult in the little finger than in the ring finger. While use of the flexor digitorum superficialis for intrinsic transfer simply corrects clawing deformity and restores synchronous finger flexion, grip strength will be further decreased by approximately 21 percent, and total active range of motion by 7 percent. Correction is best achieved by transfer of a wrist motor with tendon graft into index, middle, ring, and little digits, despite limitation of clawing to the ring and little digits. Pinch should be augmented by metacarpophalangeal joint fusion rather than by interphalangeal joint fusion. When combined with extensor carpi radialis brevis adductor plasty, pinch strength can be doubled.

Hand↗
PubMed1987

Dual innervated index to thumb cross finger or island flap reconstruction.

Partial volar amputations of the entire thumb pulp require soft tissue coverage that provides not only padding and protection for exposed bone and tendons, but also restoration of discriminative sensation. A modification of the radial sensory innervated cross finger flap from index to thumb is described, which includes separate reinnervation of the flap by repair of the dorsal sensory branch of the index radial digital nerve to the ulnar digital nerve of thumb. The anatomical basis for this flap is discussed and two example cases presented. Sensory reinnervation is rapid and does not require cortical reorientation.

Adult↗