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Biomedical subjects

R J Noble

Publications and source records attributed to R J Noble.

At least 55 records · Page 3Linked to original sources
PubMed1978

Stroke volume calculated from the mitral valve echogram in patients with and without ventricular dyssynergy.

A formula was derived for calculating mitral valve stroke volume (MVSV) using the rate of mitral valve (MV) opening (DE slope on the MV echogram), the vertical disease between the mitral leaflet echoes early in diastole (EE), the electrocardiographic PR interval and heart rate. The formula was tested prospectively on 80 consecutive patients from whom 95 simultaneous MV echograms and either thermodilution (45) or Fick (50) cardiac outputs were obtained. Sixteen patients were normal; 54 had coronary artery disease; three had cardiomyopathy; and seven had nonrheumatic mitral regurgitation (MR). Linear regression for stroke volume was r = 0.90, SEE +/- 6, and for cardiac output r = 0.83, SEE +/- 0.5 liter for the 73 patients without MR. The presence or absence of ventricular dyssynergy did not alter statistical findings. MVSV consistently overestimated forward stroke volume for the seven patients with MR. This study shows that the MV echogram provides an accurate, widely applicable method for calculating MVSV.

Cardiac Catheterization↗
PubMed1977

Treatment of recurrent ventricular tachycardia and fibrillation with aprindine.

Twenty-three patients with recurrent ventricular tachycardia or ventricular fibrillation, or both, were treated with aprindine, a new antiarrhythmic agent. It was found that: (1) no patient had a recurrence of ventricular fibrillation after aprindine therapy was begun, except as a terminal event subsequent to the development of acute myocardial infarction and cardiogenic shock or refractory congestive heart failure; (2) 6 patients experienced ventricular tachycardia after the loading dose, but with continued aprindine therapy the ventricular tachycardia was suppressed in 3 of these 6 patients, and a fourth patient was asymptomatic during brief paroxysms of ventricular tachycardia; (3) in 2 patients, aprindine was ineffective and was discontinued; (4) electrical cardioversion was not required in any patient receiving aprindine; (5) premature ventricular extrasystoles were decreased in 18 of the 23 patients treated with aprindine; (6) aprindine was discontinued in 1 patient because of intolerable side effects, although ventricular arrhythmias were suppressed in this patient; and (7) 5 patients died from acute myocardial infarction or severe heart failure while receiving aprindine.

Administration, Oral↗
PubMed1977

Pacemaker-induced endocardial friction rub.

Two patients had a typical sounding cardiac friction rub after placement of a temporary transvenous pacemaker. Absence of myocardial perforation was documented in one patient during thoracotomy for placement of an epicardial electrode and in the other with an electrogram recorded from the pacemaker as it was being withdrawn. The rubs disappeared during pacemaker removal. These cases are believed to represent endocardial friction rubs resulting from contact of the pacing wire with the endocardium.

Adult↗
PubMed1976

Early diastolic sound associated with mitral valve prolapse.

A patient with the prolapsing mitral valve syndrome demonstrated a most striking early diastolic sound. Noninvasive study with phonocardiograms, external pulse recordings, and echocardiograms lead us to believe that the sound may be related to the initial opening movement of the mitral valve. To our knowledge, such a mechanism for the production of a diastolic sound has not been previously reported.

Adult↗
PubMed1976

Normalization of abnormal T waves in ischemia.

Inverted T waves due to coronary artery disease and previous myocardial infarction were observed to revert ot normal, upright position during ischemia in 38 patients. The normalization of inverted T waves was seen on the electroencephalograms of 19 patients during spontaneously occurring angina pectoris and of 11 patients when ischemia was provoked by treadmill exercise; for 8 patients, normalization occurred during the administration of isoproterenol hydrochloride and during the consequent episode of angina pectoris. The mechanism for normalization may be the algebraic sum of the extent of ST segment elevation and the amplitude of the T waves of acute ischemia plus the extent of preexisting ST segment depression and the degree of T wave inversion, to result in isoelectric ST segment and upright T wave. As with myocardial infarction, reciprocal changes may also be recorded. However, the reciprocal nature may be masked since either acute ST segment elevation of T wave inversion, or both, may not be recorded in the leads reflecting the ischemic area because of normalization.

Acute Disease↗
PubMed1975

Dissociation of the inotropic effect of digitalis from its effect on atrioventricular conduction.

The relation between sequential changes in left ventricular contractility and atrioventricular (A-V) nodal conduction and refractoriness was assessed in open chest dogs during intravenous administration of acetylstrophanthidin (5 mug/kg) at 5 minute intervals until toxic arrhythmias developed. At each time interval, high fidelity left ventricular pressure, its electronic derivative (dP/dt) and a His bundle electrogram were simultaneously recorded and the A-V nodal refractory period was measured by graded trains of stimuli. Animals were studied with an intact autonomic state (Group I), with pharmacologic blockade of both the beta adrenergic and parasympathetic system (Group II) and with parasympathetic blockade (Group III). Whereas contractility increased in response to small doses of digitalis, displaying a linear dose-response relation independent of autonomic tone, A-V nodal transmission indexes responded minimally to less than 50 percent of the toxic dose of digitalis, and the response was dependent upon autonomic tone. These results indicate a dissociation between the effects of digitalis on contractility and A-V transmission in that the major drug action on the ventricular contractile mechanism is a direct, linear one in contrast to the nonlinear response of A-V nodal transmission, which is predominantly mediated through the autonomic system. Clinically, these observations imply that the optimal dose and serum level of digitalis required to treat congestive heart failure may differ significantly from those required to treat supraventricular tachycardias, the therapeutic response of the latter being largely determined by the underlying autonomic tone.

Animals↗
PubMed1975

Nitroglycerin and premature ventricular complexes in myocardial infarction.

Because of clinical observations suggesting that nitroglycerin may suppress premature ventricular complexes during acute ischaemia, a study was undertaken to assess the effect of nitroglycerin on the incidence of premature ventricular complexes in patients with acute myocardial infarction. Forty patients with acute myocardial infarction were studied. Twenty-six patients received 0.4 mg nitroglycerin sublingually every 4 hours for the first 24 hours after admission to the coronary care unit. The total premature ventricular complex count for the 26 patients for 15 minutes before nitroglycerin was 592, and 276 for the 15 minutes after the drug (P less than 0.005). In the remaining 14 patients on the same nitroglycerin schedule, a single electrocardiographic lead was continuously recorded on tape. During the first hour after nitroglycerin, the premature ventricular complex count decreased by 58 per cent, and the second and third hours showed a decrease from control count of 71 and 65 per cent respectively. By the end of 4 hours the ectopic count was back to control level. The data indicate that nitroglycerin may decrease the number of premature ventricular complexes for up to 3 hours in patients with acute myocardial infarction. The mechanism of action of nitroglycerin is not elucidated by this study, but the observation may be of value in further studies of specific antiarrhythmic therapy and prevention of arrhythmias in patients with coronary artery disease.

Administration, Oral↗
PubMed1975

An unusual precordial pulse and sound assoicated with large pericardial effusion.

An unusual, high-pitched, early diastolic sound coinciding with a prominent, sharp precordial pulse was observed in a patient with a large chronic pericardial effusion. The pulse and sound coincided exactly with the anterior excursion of the heart within the fluid-filled pericardial sac, suggesting that the sound and pulse result from the ballistic effect of the heart striking the anterior pericardium and chest wall. This finding may be specific for large pericardial effusion with a "swinging heart."

Aged↗