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Biomedical subjects

D L Ross

Publications and source records attributed to D L Ross.

At least 127 records · Page 7Linked to original sources
PubMed1982

Surgery for ventricular tachycardia: efficacy of left ventricular aneurysm resection compared with operation guided by electrical activation mapping.

Sixty-five patients underwent surgery for recurrent ventricular tachyarrhythmias. The 32 patients in group 1 underwent simple left ventricular aneurysm resection. The 33 patients in group 2 underwent myocardial resection or incision guided by intraoperative mapping of the electrical activation sequence. The clinical, hemodynamic and angiographic characteristics of the two groups were similar. Although actuarial survival in the two groups was similar through 24 months, late attrition in group 1 patients has left only 21 +/- 13% (+/- SEM) alive by life-table analysis at 94 months. Arrhythmia recurrence has been greater in group 1 than in group 2. In group 1, 50 +/- 9% of patients at risk at 3 months had recurrences by actuarial analysis. In group 2, only 13 +/- 6% at 1 month, 17 +/- 7% at 3 months and 29 +/- 9% at 24 months relapsed. Death was caused by ventricular tachyarrhythmias in 12 of the 17 patients (71%) who died in group 1, but only three of 12 (25%) who died in group 2. We conclude that surgery of the left ventricle, guided and modified by intraoperative mapping of the electrical activation sequence, frequently eliminates ventricular tachyarrhythmias and may be more effective than blind resection of left ventricular aneurysm.

Electrocardiography↗
PubMed1982

Antiarrhythmic drug combinations in the treatment of ventricular tachycardia.

Combinations of antiarrhythmic drugs are frequently used to treat refractory ventricular tachycardia (VT), but few scientific data support this practice. We examined the efficacy and electrophysiology of 110 antiarrhythmic drug combination trials at electrophysiologic study in 74 patients with recurrent ventricular tachycardia. Lidocaine was combined with quinidine in 33 trials, procainamide in 22 and encainide in 20. Propranolol was combined with quinidine in 17 trials, procainamide in 12 and encainide in six. All individual drugs tested (except propranolol, which was usually not tested individually) had failed at electrophysiologic study or clinically in the presence of usually accepted plasma concentrations. Lidocaine in combination with quinidine was effective in 3% of the trials, with procanamide in 5% and with encainide in none of the trials. Propranolol in combination with quinidine was effective in 18% of the trials, with procainamide in 17% and with encainide in none of the trials. The electrophysiologic effects of the tested drug combinations were dominated by the individual effects of the type 1 antiarrhythmic agents. We conclude that the tested antiarrhythmic drug combinations are infrequently effective in preventing VT induction at electrophysiologic study when each agent has failed individually. The addition of lidocaine or propranolol to quinidine, procainamide or encainide does not produce significant synergistic or new effects on the electrophysiologic variables analyzed.

Aged↗
PubMed1982

Nonabsorptive hydrocephalus associated with nephropathic cystinosis.

A child with nephropathic cystinosis developed seizures and coma. CT showed prominent sulci and slight ventricular enlargement. Nuclear cisternogram was normal. Despite successful renal transplantation and treatment of hypothyroidism, neurologic recovery was poor. CT and nuclear cisternogram 5 months later showed moderate panventricular and subarachnoid space enlargement and abnormal ventricular isotope retention. Ventriculoperitoneal shunt placement was followed by improved intellectual function, resolution of pyramidal tract signs, and control of seizures. Anisotropic crystals consistent with cystine were demonstrated in biopsy samples of arachnoid and cerebral cortex. Nonabsorptive hydrocephalus may have resulted from deposition of cystine in the meninges.

Arachnoid↗
PubMed1982

Hypomelanosis of Ito (incontinentia pigmenti achromians)--a clinicopathologic study: macrocephaly and gray matter heterotopias.

We studied a boy with macrocephaly, hypotonia, pigmentary retinopathy, unilateral whorled hypopigmented skin lesions, and seizures. Skin biopsy confirmed the clinical diagnosis of hypomelanosis of Ito. Postmortem examination at age 22 months revealed a severe neuronal migrational defect that altered the cerebral cortex architecture of white matter. There were many gray matter heterotopias characterized by altered neurons and giant cells. Electronmicroscopy revealed the astrocytic nature of the giant cells. Embryologic migration of both melanoblasts from neural crest and cortical neurons occurs in the second trimester, suggesting a common mechanism for the developmental pathology of skin and brain.

Brain↗
PubMed1981

Termination of circus movement tachycardia utilizing an accessory atrioventricular pathway by retrograde concealed penetration of the atrioventricular node through the bundle branch system. A mechanism of tachycardia termination in Wolff-Parkinson-White syndrome.

A 30 year old woman with Wolff-Parkinson-White syndrome underwent electrophysiologic study for investigation of circus movement tachycardia utilizing the accessory pathway for retrograde conduction. The accessory pathway was located on the right side. Episodes of circus movement tachycardia with left and right bundle branch block were induced. Some episodes of circus movement tachycardia with left bundle branch block terminated spontaneously. Two episodes of spontaneous termination at the level of the atrioventricular (A-V) node were preceded by prolongation of the H-V interval causing delay in atrial activation. This delayed atrial cycle was then followed paradoxically by spontaneous termination of the tachycardia in the A-V node. A similar phenomenon could be demonstrated reproducibly with single echo beats induced by coronary sinus extrastimuli. It appears that retrograde concealed penetration of the A-V node through the bundle branch system during anterograde left bundle branch block is the most likely mechanism for this phenomenon.

Adult↗
PubMed1981

The treatment of ventricular tachycardia using an automatic tachycardia terminating pacemaker.

Implanted cardiac pacemakers may be used in the management of selected patients with ventricular tachycardia unresponsive to other forms of medical and surgical therapy. We would like to report the successful treatment of such a patient utilizing a new multiprogrammable automatically activating ventricular burst pacemaker. Thorough electrophysiologic study preceded implantation, and was instrumental in choosing an effective terminating technique, in identifying the need for adjunctive drug therapy, and in testing the safety and efficacy of the implanted system.

Aged↗
PubMed1981

Spontaneous termination of circus movement tachycardia using an atrioventricular accessory pathway: incidence, site of block and mechanisms.

The incidence, mechanisms and sites of block of spontaneous termination of circus movement tachycardia (CMT) using an atrioventricular accessory pathway (AP) were analyzed in 24 consecutive patients (17 with Wolff-Parkinson-White syndrome and seven with a concealed AP) who were not receiving antiarrhythmic drugs. Spontaneous termination of tachycardia occurred in 10 patients (105 episodes). A reduced "safety margin" of tachycardia was the only factor that was significantly more common in the patients who manifested spontaneous termination (p less than 0.01). The site of spontaneous block was located in the AP in six patients (50 episodes), atrioventricular node (AVN) in six patients (37 episodes) and His-Purkinje system (HPS) in three patients (18 episodes). At least 14 mechanisms leading to block in the tachycardia circuit were identified. Labile conduction during tachycardia occurred at multiple sites (AVN, His bundle, bundle branches, and AP). Analysis of the duration of tachycardia before spontaneous termination showed a characteristic time pattern for block at each site, consistent with the autonomic and electrophysiologic changes that occur after induction of tachycardia. Spontaneous termination of CMT using an AP is a common phenomenon. Many mechanisms are involved, which are often complex and dependent on interplay of the electrophysiologic characteristics of the components of the tachycardia circuit.

Adolescent↗
PubMed1980

Initiation and termination of ventricular tachycardia by supraventricular stimuli. Incidence and electrophysiologic determinants as observed during programmed stimulation of the heart.

In 7 of 43 patients in whom a sustained ventricular tachycardia could be induced during programmed electrical stimulation by a single ventricular premature stimulus, an identical tachycardia could also be initiated by a single atrial premature stimulus. This phenomenon was observed only in those patients in whom the ventricular tachycardia could be induced by a single ventricular extrastimulus having a prematurity index (ratio between the longst ventricular premature stimulus interval resulting in tachycardia and th duration of the basic cycle length of the paced ventricular rhythm) above 54 percent. No single instance of initiation of ventricular tachycardia by atrial premature stimuli was observed in patients with a ventricular prematurity index below 54 percent or requiring more than one consecutive ventricular extrastimulus to have tachycardia initiated. Other features of patients showing initiation of ventricular tachycardia by atrial premature stimuli were a right bundle branch block configuration of the QRS complex during tachycardia in all seven patients and a relatively slow rate during tachycardia. In one patient ventricular tachycardia was terminated by a conducted atrial premature stimulus.

Adult↗
PubMed1980

Multiform ventricular tachycardia.

Electrophysiological studies were performed in three patients with chronic recurrent ventricular tachycardia (VT) associated with coronary artery disease. In each case the ventricular origin of the tachycardia was confirmed and induction of tachycardia by programmed stimulation suggested a re-entry mechanism. Multiple types of ventricular tachycardia were observed which differed in cycle length, QRS morphology, timing of local epicardial and endocardial ventricular electrograms and the use of the specialized conduction system for propagation. There was evidence of one or more re-entry circuits arising in or near previously infarcted areas, with features of cycle length alternation, change in exit points and variations in subsequent conduction through the myocardium and specialized conduction tissues. These findings suggest multiform VT can be due to a number of factors. A modified surgical approach is recommended for management of medically refractory VT when there is evidence of multiple types.

Adult↗
PubMed1980

Comprehensive clinical electrophysiologic studies in the investigation of documented or suspected tachycardias. Time, staff, problems and costs.

To assess time, staff, problems and costs involved in clinical electrophysiologic studies for documented or suspected tachycardia, 33 consecutive cases were analyzed prospectively. At least seven staff members were used for each study. Insertion of catheters required 24--105 minutes (mean 63 +/- 20 minutes). Programmed stimulation required 12--210 minutes (mean 87 +/- 38 minutes). Total fluoroscopy times were 6--67 minutes (mean 22 +/- 15 minutes). Each study used 360--2100 feet (mean 1260 +/- 390 feet) of recording paper. Detailed analysis of tracing took 1--11 hours (mean 5 +/- 2.5 hours). Delays occurred during electrophysiologic study in 25 cases (76%), with multiple causes of delay in 14 cases (42%). These were caused by 1) difficulty in obtaining venous access (five patients); 2) difficult initial catheter placement (15 cases); 3) repositioning of catheters during stimulation (17 cases); 4) sustained atrial fibrillation (four cases). Coronary sinus catheterization was achieved from the groin in 21 of 27 cases (78%) in whom a sustained attempt was made. The approximate cost of each study was greater than $800. Our data show that clinical electrophysiologic studies in the investigation and management of tachycardia are difficult, time-consuming and expensive.

Adolescent↗
PubMed1979

Chronic diphenylhydantoin therapy does not reduce plasma 25-hydroxy-vitamin D.

A randomized controlled study was performed to investigate the effect of 2 years' monitored diphenylhydantoin (DPH) therapy on plasma 25-hydroxyvitamin D (25-OHD) in non-epileptic, non-institutionalized subjects. Mean +/- SEM plasma 25-OHD of 18 DPH-treated subjects at the end of 2 years' drug treatment was 59 +/- 8 nmol/l (23.6 +/- 3.2 ng/ml), which was not decreased compared to that of eighteen control subjects (54 +/- 8 nmol/l, 21.6 +/- 3.2 ng/ml). In addition, mean plasma 25-OHD had not changed 1 month after ceasing DPH. The treated group had a higher mean serum alkaline phosphatase (SAP) during DPH treatment, attributable to hepatic enzyme induction. It is concluded that therapeutic doses of DPH without other anticonvulsants do not have a clinically significant effect on plasma 25-OHD.

Adult↗
PubMed1979

Chronic recurrent ventricular tachycardia--an electrophysiological study.

Electrophysiological techniques were used to study 17 patients with chronic recurrent ventricular tachycardia. Twelve of the patients had coronary disease, while eight had pre-existing intraventricular conduction defects. The site of origin of the tachycardia as deduced by analysis of the QRS morphology correlated well with the electrocardiographic evidence of the site of the old infarction. Ventricular tachycardia was induced by pacing techniques in eight patients while it occurred spontaneously during the study in two others. In only four of the eight patients in whom tachycardia was induced, could the arrhythmia be reinduced; the arrhythmia could not be reproduced in one, while reproducibility was not assessed in the remaining three. Tachycardia was terminated by pacing techniques in six patients and by DC cardioversion in four. Ventricular tachycardia was initiated with a run of "torsade de pointes" in four patients. Ventricular tachycardias with varying morphology were observed in three patients. Electrophysiological study was of significant benefit in patient management in 14 of the 17 patients, particularly those with pre-existing intraventricular conduction defects, undocumented tachycardia or undocumented syncope.

Adult↗
PubMed1979

Similar QRS morphology in sinus rhythm and ventricular tachycardia.

A 74-year-old man with coronary artery disease and bifascicular block suffered recurrent tachycardia. Although the similarity of QRS morphology in tachycardia and sinus rhythm suggested a supraventricular origin, His bundle electrocardiography and programmed stimulation showed a ventricular origin. Digitalis toxicity was not an etiological factor and there was no evidence to suggest a His bundle tachycardia. The case illustrates that in occasional circumstances the onset of ventricular tachycardia may produce no change in QRS morphology thus making the diagnosis by conventional electrocardiographic criteria difficult.

Aged↗
PubMed1979

Electrophysiological studies in patients with the Wolf-Parkinson-White syndrome.

Electrophysiologic studies in patients with the Wolff-Parkinson-White (WPW) syndrome are performed for diagnostic and therapeutic reasons. Surface electrocardiographic leads plus intracardiac electrograms from different locations are stimultaneously recorded. Programmed electrical stimulation of the heart permits confirmation of pre-excitation in questionable cases and assessment of the mechanism of the arrhythmias which these patients develop as well as their therapeutic approach. The most frequent form of paroxysmal regular tachycardia observed in WPW is based on an AV-junctional re-entry mechanism utilizing the accessory pathway in the retrograde direction. The second clinically relevant arrhythmia encountered in these patients is atrial fibrillation with very rapid ventricular rates due to almost exclusive A-V conduction by way of the accessory pathway. Ventricular fibrillation may occasionally ensue as a result of these fast ventricular rates during atrial fibrillation. Determination of the antegrade effective refractory period of the accessory pathway may identify the group of patients prone to the development of this complication. The intravenous injection of Ajmaline can by a non-invasive aid in the selection of patients for further electrophysiological evaluation when this drug fails to induce complete antegrade block over the accessory pathway during sinus rhythm. Patients with tachyarrhythmias which are difficult to control with conventional drug therapy should undergo an electrophysiological investigation to select either more effective antiarrhythmic treatment or, in medically refractory patients, appropriate pacing or surgical techniques.

Anti-Arrhythmia Agents↗
PubMed1978

Anticoagulation in renal vein thrombosis.

Long-term anticoagulation therapy was evaluated in two patients with renal vein thrombosis and the nephrotic syndrome. Neither patient exhibited peripheral thromboemboli. Moreover, the renal vein thrombus resolved in both cases after eight months on a regimen of oral anticoagulant therapy. Glomerular filtration rate remained stable despite persistence of the nephrotic syndrome. These results suggest that long-term anticoagulation may be of distinct value in nephrotic patients with renal vein thrombosis.

Aged↗