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Biomedical subjects

J W Linhart

Publications and source records attributed to J W Linhart.

At least 19 recordsLinked to original sources
PubMed1978

A new method for measurement of sinoatrial conduction time.

This study describes a new method (NM) for estimation of sinoatrial conduction time (SACT), which utilizes constant atrial pacing (AP) instead of the premature atrial beats (PABs) used in the method reported in 1973 by Strauss et al. The SACTs were obtained by both methods in 20 patients. The SACT by the Strauss method (SM) was calculated as A2A3 minus A1A1. The NM consists of high right AP for a train of eight consecutive beats at rates less than or equal to 10 beats/min faster than the sinus rhythm. The interval between the last paced atrial electrogram (Ap) and the first escape atrial electrogram (A) of sinus origin (Ap-A) was measured along with several post pacing sinus cycles. The SACT by the NM was calculated as follows: SACT = Ap-A minus A1A1. The effect of AP at higher rates was also analyzed. In two patients, the SACT with the SM could not be defined, as all the A2A3 intervals were fully compensatory; with the NM the SACT was 217 and 320 msec. In the remaining 18 patients the SACT was obtainable by both methods. With SM, the SACT ranged 105--452 msec (mean 219 +/- 102 SD) and with the NM it was 85--492 msec (mean 201 +/- 112 SD), and the difference was statistically significant (P = 0.0162). The coefficient of correlation between the two methods was r = 0.97. During AP at faster rates, a rate related increment in Ap-A intervals and also post pacing sinus cycles was noted. This study describes a new and simple method for measurement of SACT in man.

Adult↗
PubMed1978

Tricuspid insufficiency associated with aneurysm of the ventricular septum.

Because of the anatomic relation of an aneurysm of the membranous ventricular septum (AMVS) to the tricuspid septal leaflet or because of the tricuspid septal leaflet involvement in the aneurysm formation, dysfunction of the tricuspid valve is likely to occur in patients with AMVS. The auscultatory manifestations of the resultant tricuspid insufficiency (TI) could be masked by the systolic murmur of the ventricular septal defect (VSD), which is often present in these patients. The presence of TI is suggested by phonocardiographic findings in five patients with AMVS and is further supported by intracardiac phonocardiography and angiocardiography. After inhalation of amyl nitrite, a pansystolic murmur appeared in three patients, and the intensity of the pansystolic murmur increased significantly in two patients. Inhalation of amyl nitrite reduces the systemic resistance, resulting in decreased systemic pressure and diminished intensity of the murmur of a small VSD. Augmentation of the systemic venous return is responsible for increased intensity of TI murmur.

Amyl Nitrite↗
PubMed1975

Delayed opening of Beall mitral prosthetic valve detected by echocardiography.

A 47-year-old woman in normal sinus rhythm developed frequent pulse deficits, immediately following mitral valve replacement with a Beall disc prosthesis. Emergency bedside simultaneous tracing of echocardiogram, phonocardiogram and arterial pulse revealed a delayed opening of the disc with various timing intervals in diastole, and suggested some form of interference with normal disc motion. An interfering papillary muscle remnant was later confirmed and corrected by reoperation.

Echocardiography↗
PubMed1975

Sequential atrioventricular pacing as a stress test. Evaluation of left ventricular function in second-degree AV heart block developing during atrial pacing.

Advanced or second-degree atrioventricular (AV) heart block pre-existing or developing during atrial pacing (AP) at low heart rates of smaller than 130 per minute, limits the value of AP to stress the left ventricle. When Wenkebach type AV block is present, the heart rate can be increased by administration of atropine before atrial pacing or by right ventricular pacing. Atropine, however, occasionally may cause serious supraventricular or ventricular arrhythmias, and high rate right ventricular pacing is not tolerated by many patients with left ventricular dysfunction because of the absence of the atrial contribution. Twenty-eight out of 101 patients with angina pectoris (27.7 percent) developed second degree AV heart block during atrial pacing studies performed for evaluation of left ventricular function. In 8 of the 28 patients, sequential AV pacing (SP) was performed successfully, with the heart rate being increased to 150-167 per minute. In 4 of the 8 patients, left ventricular dysnfunction was demonstrated during and immediately after SP. Typical angina pectoris developed in two of the four patients during SP, one of whom proved to have normal coronary arteriogram. Sequential AV pacing is an alternative method to increase the heart rate for the purpose of stressing the left ventricle when advanced degree or second-degree AV heart block pre-exists or develops during right atrial pacing. In some patients the method of SP might be preferable to administration of atropine or to ventricular pacing.

Adult↗
PubMed1975

Echocardiography in endocardial cushion defects: a preoperative and postoperative study.

Echocardiographic studies were performed on 14 patients with endocardial cushion defects of different anatomic varieties. Four patients were studied again after operation. Patients with partial atrioventricular canal (PAVC) showed multiple systolic echoes on mitral valve echogram, with significant mitral-septal apposition in diastole. The left ventricular outflow (LVO) appeared significantly narrowed. The septal motions were paradoxic. After corrective operation, an increase in the width of the LVO was noted and mitral-septal apposition appeared to be less pronounced. Multiple systolic echoes, however, reappeared and persisted. The echocardiograms in patients with complete atrioventricular canal (CAVC) were characterized by wide excursion of an apparent single atrioventricular valve. The echoes of the mitral component of the common anterior leaflet moved anteriorly into the right ventricular cavity and overshadowed the tricuspid component in diastole. In addition, patients with CAVC and divided and medially attached common anterior leaflets had solitary mitral and tricuspid echograms. This feature differentiates this group of patients from those patients with CAVC with undivided freefloating common anterior leaflet.

Adolescent↗
PubMed1975

Dissection and rupture of the ascending aorta. Unusual complications of aortocoronary bypass surgery.

This is a report concerning two cases of unusual complications, dissection and rupture of the ascending aorta, secondary to saphenous vein bypass surgery. We recommend that evaluation of patients undergoing saphenous vein bypass surgery include careful image-intensifier fluoroscopic examination during coronary arteriography. If aneurysmal dilatation of the aorta or calcification is observed, ascending aortography should be performed to better evaluate the aorta, and surgeons should be alerted to use appropriate maneuvers and techniques to minimize the risk of complications in the aortic site of the vein anastomosis. Internal mammary coronary-artery bypass should be the procedure of choice in such conditions.

Aortic Aneurysm↗