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Biomedical subjects

G Brynjolfsson

Publications and source records attributed to G Brynjolfsson.

At least 19 recordsLinked to original sources
PubMed1984

Influence of cardiac denervation on subsidiary atrial pacemaker stabilization.

Overdrive suppression was determined by measuring cardiac cycle lengths after rapid atrial pacing in nine alert conscious dogs sustaining total intrapericardial denervation. Rapid atrial pacing was performed at 125-400% of spontaneous heart rate for 30 s and at 200% spontaneous rate for 30, 60, 120, and 180 s, with and without cholinergic (atropine 0.2 mg/kg iv) or adrenergic blockade (propranolol 0.5 mg/kg iv). Corrected recovery time (CRT) was defined as the first recovery cycle length minus average control cycle length. To compare responses of the intact sinoatrial node (SAN) and subsidiary atrial pacemakers, CRT was measured in the conscious animal before and after SAN excision. Immediately after SAN excision, a junctional rhythm was frequently observed, but within a short time (min-h), subsidiary atrial pacemaker dominance was established with well-formed P waves and P-R interval averaging 85.3 +/- 3.4 ms. CRT before SAN excision ranged from 100 to 300 ms. Following pacing at 125-400% of spontaneous heart rate soon after SAN excision, CRT was markedly prolonged, ranging up to 6,000 ms. Atropine and propranolol did not influence CRT in the denervated preparation. CRT of subsidiary atrial pacemakers in the normally innervated dog heart returned to control pre-SAN excision values in 1-2 wk. In the denervated heart complete autonomic denervation exaggerated time required for return to control CRT values to 5-8 wk.

Animals↗
PubMed1980

Gastroesophageal cardiac fistula due to perforation of an esophagogastric anastomotic ulcer into the left atrium.

A case of gastroesophageal cardiac fistula is presented. Resection of carcinoma of the gastroesophageal junction was followed by the development of a penetrating ulcer at the anastomosis site with perforation into the left atrium. Candida albicans was demonstrated growing along the tract. There was severe organizing fibrinous pericarditis and multiple microabscesses in the brain. No food emboli were found.

Brain↗
PubMed1980

Atrial ectopic foci in the canine heart: hierarchy of pacemaker automaticity.

The sinoatrial node (SAN) and adjacent tissue of the sulcus terminalis were surgically excised in sequential multiple sections to study the location and intrinsic rate of emerging pacemakers in the acute open-chest dog. Under chloralose anesthesia total of 17 ectopic atrial pacemakers emerged in 12 dogs ranging in location from the anterior interatrial band, midsulcus terminalis, and junction of the inferior vena cava-inferior right atrium. Four AV junctional and one idioventricular pacemakers also emerged in these experiments. Each successively inferior focus had a slower rate than the SAN. The average heart rate of the atrial ectopic pacemakers was 73 +/- 4% of the SAN but that the AV junctional pacemakers was 56 +/- 4% of the SAN (P less than 0.05). The greatest reductions in rate were achieved with total excision of the SAN and entire sulcus terminalis, but in only 50% of the animals did this result in a junctional rhythm. The location and rate of atrial ectopic foci support the notion that the AV junctional region is not the fastest pacemaker in the absence of the classically defined SAN and suggest that atrial ectopic pacemakers are intermediate in the hierarchy of cardiac pacemakers in the dog.

Action Potentials↗
PubMed1980

Cardiac arrhythmias after chronic embolization of the sinus node artery: alterations in parasympathetic pacemaker control.

Embolization of the sinus node artery was accomplished in dogs by injecting rapidly hardening vinyl latex into the sinus node artery. Embolization immediately shifted the pacemaker to a junctional focus; however, with time postoperatively, the pacemaker shifted to an atrial site. Variable episodes of pacemaker failure, sinoatrial block, junctional rhythm, wandering atrial pacemaker and idioventricular escape rhythms were commonly observed on Holter monitor in isolation but only rarely when the dog was in the laboratory. Severe bradycardia (38.9 +/- 3.7 beats/min) was the predominant rhythm by 3-6 months postoperatively. In addition, these same dogs had a greater overall increase in heart rate after atropine than normal dogs (17.5 +/- 13.5 vs 116.6 +/- 15.9 beats/min above control; p less than 0.02). Responses to vagal stimulation in this group were abnormal, as long periods of asystole and bradycardia were observed after stimulation was terminated. These data suggest an alteration in parasympathetic pacemaker control after chronic embolization of the sinus node artery.

Animals↗
PubMed1978

Cardiac pacemakers in absence of the SA node: responses to exercise and autonomic blockade.

Surgical excision of the sinoatrial node, verified histologically, is followed by a supraventricular (atrial) rhythm in both resting and exercising dog whether anesthetized or conscious. The ECG is characterized by a definitive P wave and associated atrial electrograms. Waxing and waning in heart rate, generally referred to as sinus arrhythmia continues in the awake animal after complete excision of the SA node. This arrhythmia is responsive to both adrenergic and cholinergic interventions, thus indicating the presence of both sympathetic and parasympathetic regulation of subsidiary atrial pacemaking tissues.

Adrenergic beta-Antagonists↗
PubMed1978

Comparison of SA nodal and subsidiary atrial pacemaker function and location in the dog.

A 3-4 cm length of sulcus terminalis tissue including the sinoatrial node (SAN) was excised from 14 dogs. After an initial junctional rhythm with SAN excision a P wave emerged within days to weeks in 12 animals. Maximum heart rates of the SAN (preoperative) in response to exercise (276 +/- 15 beats/min), isoproterenol infusion in conscious animals (272 +/- 11 beats/min), and stellate stimulation during anesthesia (273 +/- 9 beats/min) were significantly greater than subsidiary pacemakers (postoperatively) for exercise (219 +/- 9 beats/min), isoproterenol (226 +/- 8 beats/min), and stellate stimulation (197 +/- 9 beats/min). During a final experiment, electrophysiological mapping of the area of earliest epicardial activation (pacemaker location) was carried out. By use of a suction electrode in reference to plunge electrodes located in the anterior interatrial band (AIB), eustachian ridge of the coronary sinus, and limbus of the fossa ovalis, the pacemaker was located at the inferior vena cava-inferior right atrial junction in 80% of the animals mapped. During isoproterenol infusion the foci shifted to regions of the AIB in 70% of the animals mapped. The concept of pacemaker hierarchy is discussed.

Animals↗
PubMed1977

Granulomatous myocarditis secondary to cornstarch.

A 44-year-old white female with chronic rheumatic heart disease and mitral insufficiency was admitted to the hospital for cardiac catheterization and mitral valve replacement. On the ninth postoperative day the patient experienced a sudden onset of chest pain, hypotension, and died shortly therafter. Autopsy revealed multiple mural thrombi of the left atrium, one of which occluded the mitral orifice. Histologic examination showed a granulomatous and non-specific interstitial myocarditis involving all chambers of the heart. In the granulomas, both inside and outside giant cells, rounded foreign bodies were noted which stained light blue with hematoxylin and eosin, red with the periodic acid Schiff reagent, dark bluish-black with Gram's iodine, and showed Maltese cross birefringence under polarized light. These particles were identical with starch granules from surgical glove powder. The cause of death was acute mitral occlusion form a flapping mural thrombus.

Adult↗