Effect of digoxin on sinus nodal reentry in the dog.

The effect of digoxin on sinus reentry was examined in 20 open chest mongrel dogs during infusion of digoxin at a rate of 2.5 mu g/kg per min. The extrinsic cardiac nerve supply was removed acutely in 10 dogs and was left intact in the remaining 10 dogs. Sinus nodal reentry was relatively unaffected by digoxin in 18 of 20 dogs. In these 18 dogs, digitalis toxicity developed before reentry was abolished and was manifested as increased atrial and ventricular automaticity in 14 and as advanced atrioventricular (A-V) block in four. In the remaining two dogs, sinus nodal reentry was relatively sensitive to digoxin and was abolished before toxicity became manifest as advanced A-V block. The knowledge of the relative insensitivity of sinus nodal reentry to digoxin, at least in this experimental model, contrasts with the previously reported sensitivity of sinus nodal reentry to quinidine, and may be important in the management of sinus nodal reentry in man.

Echocardiographic findings of ventricular septal rupture in acute myocardial infarction.

Echocardiograms were recorded both before and after the clinical appearance of an autopsy-confirmed interventricular septal rupture in a patient with an acute myocardial infarction. The major findings were related to the upper portion of the interventricular septum. Before rupture, this portion of the septum was relatively akinetic with a slight anterior motion during systole, whereas after rupture there was a marked increase in the amplitude of septal motion with abrupt posterior motion occurring with the onset of ventricular diastole.

Sinus and atrioventricular nodal reentrant tachycardia in the same patient.

Sinus and atrioventricular (A-V) nodal reentry are shown to coexist in the same patient, and the following conclusions are drawn: (1) Reentry at one nodal site may mask reentry at the other nodal site, (2) concealed reentry at either site may become manifest reentry under the appropriate conditions, (3) manifest sinus nodal reentry may alternate with manifest A-V nodal reentry, and (4) a Wenckebach type phenomenon manifest in the A-V node and concealed in the sinus node may in some instances be the basis for coexistent sinus and A-V nodal reentry in man.

Wolff-Parkinson-White syndrome with 1:2 atrioventricular conduction.

The QRS complex of the Wolff-Parkinson-White syndrome is thought to represent a fusion beat resulting from conduction over the normal pathway and an anomalous pathway. This report demonstrates utilization of both of these pathways resulting in two ventricular responses from a single supraventricular impulse. The presence of "1:2" atrioventricular conduction in this case firmly supports the fusion beat theory of the Wolff-Parkinson-White syndrome.

Incidence, determinants and significance of fixed retrograde conduction in the region of the atrioventricular node. Evidence for retrograde atrioventricular nodal bypass tracts.

Of 104 consecutive patients studied in our laboratory with His bundle electrograms, atrial and ventricular pacing and the atrial and ventricular extrastimulus techniques, 18 patients in whom the existence and utilization of ventriculoatrial (V-A) bypass tracts were excluded demonstrated evidence for fixed and rapid retrograde conduction in the region of the atrioventricular node (A-V) as suggested by the following: (1) short (36 +/- 2 msec [mean +/- standard error of mean]) and constant retrograde H2-A2 intervals during retrograde refractory period studies; (2) significantly (P less than 0.025) better V-A than A-V conduction; (3) significantly (P less than 0.025) shorter retrograde functional refractory period of the V-A conducting system than of the A-V conduction system; and (4) the retrograde effective refractory period of the A=V nodal region was not attainable in any of the 18 patients. Fourteen of the 18 patients (77 percent) had a history of palpitations and 10 (51 percent) had documented paroxysmal supraventricular tachycardia; in 13 (72 percent) single echoes or sustained reentrant supraventricular tachycardia, or both, could be induced during atrial pacing or atrial premature stimulation studies, or both. During tachycardia all these 13 patients had a short (37 +/- 2.4 msec) and constant conduction time in the retrograde limb (H-Ae interval) of the reentrant circuit that was identical to the H2-A2 interval. In conclusion, fixed and rapid retrograde conduction in the region of the A-V node (1) is seen in approximately 17 percent of patients, (2) is associated with a large incidence of reentrant paroxysmal supraventricular tachycardia, and (3) suggests the presence of A-V nodal bypass tracts (intranodal or extranodal functioning in retrograde manner).

Congenitally corrected transposition of the great vessels: localization of the site of complete atrioventricular block using his bundle electrograms.

Complete atrioventricular block proximal to the bundle of His in a patient with congenitally corrected transposition of the great vessels was documented using His bundle electrograms. The spontaneous rhythnm probably originated from the bundle of His and was responsive to carotid sinus massage, atropine and isometric and treadmill exercise. These electrophysiologic observations are consistent with recent anatomic studies of congenitally corrected transposition of the great vessels.

Echocardiographic findings in isolated, surgically created tricuspid insufficiency.

The effects of surgically created tricuspid insufficiency on the right ventricular dimension and the motion of the interventricular septum were determined by serial echocardiography in a patient with a hemodynamically normal heart who underwent tricuspid valvulectomy and later tricuspid valve replacement for medically intractable bacterial endocarditis. Initially, both the right ventricular dimension (1.8 cm) and motion of the interventricular septum were normal. After valvulectomy interventricular septal motion became distinctly paradoxical (pattern A, later pattern B), and the right ventricular dimension progressively increased to 3.5 cm. After successful tricuspid valve replacement interventricular septal motion promptly returned toward normal as did the right ventricular dimension (2.2 cm). The rapid changes in these echocardiographic variables with creation and relief of acute right ventricular volume overload correspond well with results of previous work in experimental animals but differ from findings in man with chronic right ventricular volume overload.

Effects of digitalis on ventricular myocardial and His-Purkinje refractoriness and reentry in man.

The effects of digitalis on retrograde conduction and refractoriness of the His-Purkinje system, ventricular myocardium and reentry within the His-Purkinje system were studied in 17 patients using the ventricular extrastimulus (V2) technique. Studies were performed, before and 30 minutes after intravenous administration of ouabain, 0.01 mg/kg. After treatment with ouabain, there was a significant decrease in the functional refractory period (266 +/- 19 to 254 +/- 18 msec, P less than 0.001), relative refractory period (253 +/- 17 to 240 +/- 16 msec, P less than 0.001) and effective refractory period (242 +/- 23 to 231 +/- 24 msec, P less than 0.005) of the ventricular muscle. In contrast, there was no significant change in retrograde His-Purkinje conduction and refractoriness. The phenomenon of reentry within the His-Purkinje system characterized by the reentrant beat (V3) at critical retrograde conduction delays in the His-Purkinje system (V2-H2) within a narrow range of V1-V2 intervals was seen in 10 of 17 patients. Ouabain increased and shifted to the left the zone of reentry within the His-Purkinje system in 7 of 10 patients (36 +/- 23 to 55 +/- 23 msec, P less than 0.001) and decreased it by 10 to 30 msec in the remaining 3 patients. The critical V2-H2 (186 +/- 29 to 193 +/- 27 msec, difference not significant [NS]) and V1-V2 (299 +/- 30 to 294 +/- 36 msec, NS) intervals for reentry did not significantly change after ouabain. However, the minimal V1-V2 intervals (266 +/- 26 to 253 +/- 25 msec, P less than 0.025) decreased significantly, whereas the maximal V2-H2 intervals (266 +/- 40 to 239 +/- 37 msec, P less than 0.01) increased significantly. Thus, in the intact human heart, digitalis (1) significantly decreased all measures of ventricular myocardial refractoriness, (2) had no significant effect on retrograde conduction and refractoriness of the His-Purkinje system, and (3) widened the zone of reentry within the His-Purkinje system due to shortening of the functional refractory period of the ventricular muscle with attainment of longer V2-H2 delays.

Ventricular septal motion and left ventriclular dimensions during abnormal ventricular activation.

To determine the effect of abnormal ventricular activation on ventricular septal motion, left ventricular endocardial motion and left ventricular dimensions, 12 patients with normal motion were studied with echocardiography during incremental pacing of the right ventricular apex, outflow and inflow regions. Three types of abnormal ventricular septal motion were seen: The type I pattern was characterized by an early rapid preejection posterior ventricular septal motion followed by another posterior systolic motion that lasted throughout ejection, both of which were associated with septal thickening. In the type II pattern an early rapid preejection posterior ventricular septal motion was followed by an anterior ejection motion; the latter was not accompanied by septal thickening. The type III pattern consisted of an early preejection posterior ventricular septal motion followed by a mid and late systolic posterior motion: the latter motion extended through diastole. During right ventricular apical pacing, 8 of 11 patients showed a type 1 pattern, 1 a type II pattern and 2 a normal septal motion. During right ventricular outflow pacing,seven of nine patients showed a type II pattern, one a type III pattern and one a type I pattern. During right ventricular inflow pacing, eight of nine patients showed a type II pattern and one a type III pattern. At faster pacing rates patterns of types I and III changed to a type II pattern (five patients). End-diastolic dimensions decreased significantly during incremental right ventricular pacing when compared with those during sinus rhythm. End-systolic dimensions decreased significantly only during right ventricular apical and outflow pacing at maximal rates. In the seven patients who had pacing from all three sites, the decrease in left ventricular dimensions did not significantly differ when the three pacing sites were compared. These findings suggest that (1) abnormal ventricular septal motion during right ventricular pacing (induced left bundle branch block patterns) is dependent on the sequence of ventricular activation; (2) ventricular septal motion during right ventricular outflow and inflow pacing is similar to that seen in spontaneous left bundle branch block, whereas the pattern of septal motion during right ventricular apical pacing is different from that of spontaneous left bundle branch block; and (3) changes in left ventricular dimension are dependent on ventricular pacing rate but independent of pacing site.

Electrophysiologic effects of procainamide in subtherapeutic to therapeutic doses on human atrioventricular conduction system.

The effects of single intravenous infusions of 50 to 400 mg of procainamide on the functional properties of the atrioventricular (A-V) conduction system were studied in 36 patients and correlated with plasma concentrations. A 50 mg dose of procainamide resulted in a plasma concentration of less than 1.0 mug/ml and produced no electrophysiologic changes. Doses of 100, 200, 300 and 400 mg resulted in progresively increasing plasma concentrations (1.2, 1.8, 3.5 and 4.2 mug/ml, respectively). The effects of procainamide on the sinus rate were variable and not dose-related. The effects of doses of up to 300 mg on A-V nodal conduction were variable and not dose-related. Only in a dose of 400 mg did procainamide prolong A-V nodal conduction in six of seven patients. Whereas 100 mg had no effect on His-Purkinje system conduction, doses of 200, 300 and 400 mg prolonged His-Purkinje system conduction time by 6, 8 and 9 msec, respectively. Dose-related increases in atrial refractoriness started with a dose of 200 mg and became statistically significant with doses of 300 and 400 mg. The effects of procainamide on A-V nodal functional refractoriness were variable and not dose-related, but in doses of 100 to 400 mg, procainamide produced significant and progressively dose-related increases in His-Purkinje system refractoriness. Suppression of some types of ventricular arrhythmia by small doses of this drug may be explained by changes in refractoriness of the His-Purkinje system produced by doses of procainamide as small as 100 mg.

Induction of atrioventricular nodal reentrant tachycardia after atropine. Report of five cases.

After intravenous administration of 0.5 mg of atropine sustained atrioventricular (A-V) nodal reentrant tachycardia could be produced in five patients who had no prior historical or electrocardiographic evidence of supraventricular tachycardia. During the control period single atrial echo beats could be demonstrated in four of the five patients, but no instance of sustained tachycardia occurred. Atropine, known to enhance A-V nodal conduction, allowed achievement of longer A-H intervals (Case 1) and provided the necessary balance of conduction and refractoriness within the A-V nodal reentrant pathways (Cases 1 to 5) to sustain A-V nodal reentry in these patients.

Interventricular septal motion during preexcitation and normal conduction in Wolff-Parkinson-White syndrome: echocardiographic and electrophysiologic correlation.

Interventricular septal motion was studied by echocardiogram in 20 consecutive patients with documented Wolff-Parkinson-White (WPW) syndrome before and during electrophysiologic evaluation using His bundle recordings and pacing techniques. Characteristic abnormal interventricular septal motion was seen in 8 of 11 patients with type B WPW syndrome (groups I and II). All eight patients had electrocardiographic patterns consistent with an anomalous pathway located in the anterior right ventricular wall (group I). In five of these eight patients normalization of the QRS complex for one or more beats was accomplished and produced normalization of the septal motion in four; whereas in the fifth patient, who had an underlying atrial septal defect, the abnormal septal motion remained abnormal. All nine patients with type A WPW syndrome (groups III to V) had normal septal motion both during total preexcitation and during normalization of the QRS complex. The normalization of the abnormal interventricular septal motion with normalization of the QRS complex in type B WPW syndrome strongly suggests that the abnormal motion is related to an abnormal sequence of ventricular depolarization during preexcitation. Furthermore, persistent abnormal septal motion after normalization of the QRS complex suggests that other factors such as right ventricular volume overload may be responsible. Likewise, when abnormal septal motion occurs in the presence of type A WPW syndrome, an explanation other than preexcitation must be sought.

Propranolol-induced urticaria: successful therapy with tolamolol.

Urticaria with systemic effects occurred in a patient being treated with propranolol and was reproducible upon rechallenge with the drug; Successful beta-adrenergic blocking therapy was achieved using a new agent, tolamolol, with no evidence of any adverse effects.

Congenital pulmonary artery branch stenosis: association with renal artery stenosis.

A patient had multiple bilateral stenoses of the pulmonary artery and its branches with systemic hypertension associated with mild stenoses of the renal arteries. Cardiac catheterization and angiocardiography are important in the evaluation of the degree of stenoses and pulmonary hypertension. This case suggests that in a child or young person with hypertension and a loud precordial murmur, lesions other than coarctation of the aorta may be present. Unexplained systemic hypertension requires further investigative workup which is essential for proper treatment and long-term management of these patients.

"The anti-Ashman maneuver": a bedside method for distinguishing aberrancy from ventricular ectopy.

This is a report of a patient who develops new onset atrial fibrillation in the postoperative setting which is further complicated by the presence of wide beats in singles, pairs, and short runs. Presented are the differential diagnosis of these wide beats and a simple bedside maneuver to help distinguish their origin.

The Osborn wave of hypothermia in normothermic patients.

The Osborn wave (also referred to as "the J wave," "the J deflection," or "the camel's hump") is a distinctive deflection occurring at the QRS-ST junction of approximately 80% of hypothermic patients (core body temperature < or = 95 degrees F). Generally, the amplitude and duration of Osborn waves are inversely related to core temperature. We report on eight normothermic patients whose 12-lead electrocardiograms demonstrated QRS-ST junction notches similar to those seen in hypothermia. These data support the concept that the Osborn wave is not pathognomonic of hypothermia.

Attitudes of physicians regarding physician-assisted suicide.

A survey of New Jersey physicians reveals no clear consensus as to whether physician-assisted suicide should be legalized, and most physicians stated that they would not participate in such activities where it is legal to do so. Further studies need to be undertaken.

HCFA's Medicare mortality statistics for a New Jersey hospital.

We assessed the severity of illness in 40 Medicare patients with an acute myocardial infarction to determine whether HCFA's observed-to-predicted mortality ratio was related to quality of care or severity of illness. The authors present a study from a New Jersey hospital.

Advance directives for HIV-positive patients.

The authors surveyed HIV-positive patients to determine their knowledge of and interest in advance directives and their preferences for end-of-life care. The results of this study make clear the need to institute a program of education for those desiring to know more about advance directives.

Advance directives for the elderly: a survey.

In 1991, the New Jersey Legislature passed the New Jersey Advance Directives for Health Care Act. We surveyed the elderly about their knowledge and interest in advance directives, their preferences regarding end-of-life care, and whether their physicians discuss these matters.