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Biomedical subjects

R H Falk

Publications and source records attributed to R H Falk.

At least 91 records · Page 5Linked to original sources
PubMed1987

Sensitivity and specificity of the echocardiographic features of cardiac amyloidosis.

Thirty-one patients with documented cardiac amyloidosis were compared to 39 control subjects with left ventricular hypertrophy to determine specific 2-dimensional echocardiographic features of amyloid. In 16 patients, increased myocardial echogenicity was present when a single short-axis view was examined, and had a sensitivity of 63% and a specificity of 74% for the diagnosis of amyloidosis. When complete echocardiograms were reviewed (15 patients), an improved sensitivity of 87% and specificity of 81% based on increased echogenicity was seen. Increased atrial septal thickness was present in 60% of amyloid patients and no controls. The combination of increased myocardial echogenicity and increased atrial thickness was 60% sensitive and 100% specific for the diagnosis of amyloidosis. The ratio of electrocardiographic voltage (S in V1 + R in V5 or V6) to left ventricular cross-sectional area also was examined. A ratio of less than 1.5 was 82% sensitive and 83% specific for amyloid (excluding the 2 patients with left bundle branch block), but added little to the diagnosis as determined from the 2-dimensional echocardiogram.

Amyloidosis↗
PubMed1987

Cardiac activation during external cardiac pacing.

To determine which cardiac chambers are stimulated during external cardiac pacing we performed external pacing in eight normal volunteers while recording the esophageal electrogram. All subjects demonstrated evidence of pacing, which was ventricular in each case. The atrium was frequently activated retrogradely during pacing. We conclude that external cardiac pacing selectively stimulates the ventricle and is thus not of value for noninvasive atrial pacing studies.

Adult↗
PubMed1987

Transesophageal atrial pacing using a pill electrode for the termination of atrial flutter.

To determine the efficacy of transesophageal rapid atrial pacing with a "pill-electrode" for the termination of atrial flutter, we studied 14 consecutive unselected patients presenting with atrial flutter of various etiologies. The bipolar pill-electrode (interelectrode distance 13 mm) was introduced orally without sedation. Of 14 pacing attempts, atrial capture was obtained in 13 (93 percent), and sustained alteration in rhythm (atrial fibrillation, sinus rhythm or type 2 flutter) in 12 (86 percent). Normal sinus rhythm occurred in six (43 percent), in all of whom it was preceded by transient atrial fibrillation. There was no difference in baseline flutter rates, pacing rates for atrial capture, or duration of flutter between patients reverting to sinus rhythm and those remaining in flutter or converting to atrial fibrillation. Pacing was well tolerated in all but one subject. Thus, esophageal pacing with the pill-electrode was simple to perform, well-tolerated and highly successful for atrial capture in patients with atrial flutter. Although it had a lower success rate than DC cardioversion in producing sinus rhythm, the simplicity of application makes it a useful initial alternative, particularly in patients in whom cardioversion may be hazardous.

Adult↗
PubMed1987

Digoxin for converting recent-onset atrial fibrillation to sinus rhythm. A randomized, double-blinded trial.

STUDY OBJECTIVE: to determine whether digoxin is effective in converting atrial fibrillation of recent onset to normal sinus rhythm. DESIGN: randomized, double-blinded, placebo-controlled trial with a maximum 18-hour treatment period. SETTING: emergency room and medical floors of a non-referral city hospital. PATIENTS: consecutive sample of 36 patients with atrial fibrillation of 7 days' duration or less, not on digitalis glycoside or anti-arrhythmic agents, with ventricular rate between 85 to 175 beats/min, without evidence of heart failure, acute myocardial infarction, unstable angina, preexcitation syndrome, thyrotoxicosis, hypokalemia, renal impairment, or severe metabolic disturbances. INTERVENTIONS: digoxin solution in capsules or identical placebo, given in doses of 0.6, 0.4, 0.2, and 0.2 mg, at 0, 4, 8, and 14 hours, respectively, or until conversion to sinus rhythm, whichever occurred first. Continuous electrocardiographic recording by Holter monitor. MEASUREMENTS AND MAIN RESULTS: nine of eighteen patients receiving digoxin and 8 of 18 receiving placebo had a return to sinus rhythm within 18 hours of study entry (95% confidence interval for the difference in proportions, -11% to 22%). Mean time to conversion was 5.1 hours in the digoxin group and 3.3 in the placebo group (95% Cl, -3.6 to 7.0 hours). CONCLUSIONS: spontaneous reversion to sinus rhythm is common in patients with atrial fibrillation of recent onset. Digitalization was not shown to affect the likelihood of reversion to sinus rhythm, and thus cannot be recommended for this purpose in patients with atrial fibrillation.

Atrial Fibrillation↗
PubMed1986

External cardiac pacing during in-hospital cardiac arrest.

External noninvasive cardiac pacing offers a rapid and simple method of pacing the heart during an emergency. It has been suggested that early use of cardiac pacing for bradycardia or asystole may improve survival in patients who have cardiac arrest. To investigate this possibility 58 consecutive episodes of cardiac arrest occurring on the medical wards or emergency room. Twenty-six episodes underwent external noninvasive pacing for bradycardia or asystole refractory to standard drugs. Only 2 patients survived, and survival could be directly attributed to pacing in only 1 of them. Of the 32 episodes not undergoing pacing, 23 had transient asystole or bradycardia, 13 of which rapidly responded to medications. The 17 cases (53%) not undergoing pacing survived. In conclusion, when bradycardia or asystole during cardiac arrest fails to respond to standard pharmacologic measures, it is an indicator of severe myocardial damage, and attempts at cardiac pacing rarely improve survival.

Adult↗
PubMed1986

External cardiac pacing: influence of electrode placement on pacing threshold.

External cardiac pacing is a recently reintroduced, effective method for emergency cardiac stimulation. The optimal electrode position and polarity for external pacing were determined in two groups of normal subjects. In six subjects there was no significant difference in pacing threshold when electrodes were positioned as follows: negative electrode in left parasternal region, positive electrode in right subscapular region; negative electrode in left parasternal region, positive electrode in left subscapular region; or negative electrode at cardiac apex, positive electrode in right parasternal region. In the remaining ten patients, pacing attempts were ineffective when electrode polarity was reversed. We conclude that exact electrode positioning is not crucial for external cardiac pacing, as long as the anterior or apical electrode is negative.

Cardiac Pacing, Artificial↗
PubMed1985

External noninvasive temporary cardiac pacing: clinical trials.

An external cardiac pacemaker-monitor has been developed that provides safe, effective noninvasive ventricular stimulation that is well tolerated in conscious patients and allows clear recognition of electrocardiographic response. The noninvasive temporary pacemaker (NTP) has now been applied in 134 patients in five hospitals. Stimulation was tolerated well in 73 of 82 conscious patients, and nine found it intolerable. The NTP was effective in evoking electrocardiographic responses in 105 patients; the 29 failures were in the presence of prolonged hypoxia or severe discomfort. The NTP was clinically useful in 82 patients: 43 of 86 were resuscitated from emergency or expected arrest, 38 of 40 were maintained in standby readiness for up to 1 month but did not require stimulation, and one of eight patients with tachycardia obtained some clinical benefit. The NTP was especially useful in 25 patients with complications or contraindications to endocardial pacing and in 57 patients in whom insertion of an endocardial electrode was avoided.

Adult↗
PubMed1984

Cardiac arrhythmias in systemic amyloidosis: correlation with echocardiographic abnormalities.

To determine the prevalence of cardiac arrhythmias in patients with systemic amyloidosis 24 hour electrocardiographic monitoring was performed in 27 patients with primary amyloidosis and in 6 patients with familial amyloid polyneuropathy. All patients underwent echocardiographic studies. Despite a high prevalence of conduction disturbances on standard electrocardiogram, clinically significant bradyarrhythmias were rare (one patient). Complex ventricular arrhythmias (multiform, paired or repetitive beats) occurred in 14 patients (47%) with primary amyloid and 3 patients (50%) with familial amyloid polyneuropathy. The presence of cardiac arrhythmia correlated with heart failure and, more strongly, with an abnormal echocardiogram. There were four sudden deaths, all in patients with abnormal echocardiograms and complex ventricular arrhythmias. These findings suggest that complex ventricular arrhythmia on Holter monitoring is common in cardiac amyloidosis and may be a harbinger of subsequent sudden cardiac death.

Adult↗
PubMed1984

Lorcainide. A comparative trial with quinidine gluconate in patients with previously untreated ventricular arrhythmias.

The efficacy of a new antiarrhythmic agent, lorcainide, was compared with that of quinidine gluconate in a fixed-dose, randomized, crossover trial. Of 26 previously untreated patients with frequent ventricular ectopic beats documented by 24-hour ambulatory monitoring, 17 completed four weeks of therapy with quinidine and 12 with lorcainide. Of 22 patients receiving both drugs, early termination of therapy due to side effects occurred in ten (45 percent) patients receiving lorcainide and five (23 percent) receiving quinidine. Lorcainide (100 mg twice daily or three times daily, dependent on body weight) effectively suppressed ventricular arrhythmias in seven of 12 (58 percent) patients completing four weeks of therapy, and suppression by quinidine gluconate (324 mg three times daily) occurred in five of 12 (59 percent) patients. We conclude that in a dose of 100 mg twice or three times daily, lorcainide is as effective as quinidine gluconate, 324 mg three times daily, for the suppression of chronic ventricular arrhythmias. However, the high incidence of adverse reactions experienced with lorcainide make it an unacceptable agent for first-line antiarrhythmic therapy.

Adult↗