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Biomedical subjects

B W Gross

Publications and source records attributed to B W Gross.

12 recordsLinked to original sources
PubMed1985

Noninvasive detection of aortic insufficiency in patients with mitral stenosis by pulsed Doppler echocardiography.

In patients with mitral stenosis, routine noninvasive techniques are insensitive for the detection of coexistent aortic insufficiency. The ability of pulsed Doppler echocardiography to detect the presence or absence of angiographically demonstrated aortic insufficiency was evaluated in 45 patients with rheumatic mitral stenosis. Pulsed Doppler echocardiography correctly identified the presence of aortic insufficiency in 97% of the 35 patients with documented aortic regurgitation. More important, pulsed Doppler echocardiography disclosed aortic insufficiency in all 7 patients in whom it was not suspected on physical examination and in 28 of the 29 patients in whom it was not suspected by M-mode echocardiography. Pulsed Doppler echocardiography also demonstrated excellent specificity, correctly detecting the absence of aortic insufficiency in 9 of the 10 patients who had no angiographic evidence of aortic insufficiency. It is concluded that in patients with mitral stenosis, pulsed Doppler echocardiography is a useful noninvasive diagnostic test for evaluating the presence of aortic insufficiency, even when this lesion is not detectable by physical examination or M-mode echocardiography.

Adult↗
PubMed1984

Effect of amiodarone on ventricular function as measured by gated radionuclide angiography.

Myocardial size and contractility were measured by gated radionuclide ventriculography in 70 patients before and a mean of 66 days after beginning amiodarone therapy. The mean dose of amiodarone at the time of the second study was 481 mg. The mean left ventricular (LV) ejection fraction (EF) increased slightly, from 40% to 43% (p = 0.001). The mean right ventricular EF remained unchanged (38% to 39%, difference not significant [NS]). The LV end-diastolic volume (count-based method) increased by 9% (p = 0.01), but no change could be demonstrated for end-systolic volume (4%, NS). The LV stroke volume increased 19% (p = 0.001), but cardiac output remained unchanged (5%, NS) because the heart rate decreased by 9 beats/min (p = 0.001). The right ventricular end-diastolic volume increased by 12% (p = 0.01) and end-systolic volume increased by 11% (p = 0.03). Stroke volume increased by 18% (p = 0.005). There was no significant correlation between the change in LVEF and the pre-amiodarone LVEF, the time interval between studies, or with indexes of amiodarone effect (change in heart rate, QRS, QTc, TSH, amiodarone dosage). In 5 patients (7%), LVEF decreased significantly, requiring discontinuation of amiodarone therapy in 1 patient. At the time of the second study congestive heart failure was manifest in 19%, and there was a trend suggesting that congestive heart failure was more likely if the initial LVEF was less than or equal to 35% (p = 0.10). Thus, amiodarone may rarely adversely affect contractility, although myocardial contractility is typically unchanged. There is an associated small increase in the size of both ventricles.

Aged↗
PubMed1984

Ventricular fibrillation causes sudden death in Southeast Asian immigrants.

Young, male, Southeast Asian immigrants living in the United States have a high incidence of unexplained, sudden, nocturnal death. We report the cases of three patients, two Laotians and one Filipino, who were resuscitated and subsequently studied extensively. Each patient was having ventricular fibrillation when first examined by paramedics outside the hospital, and episodes of fibrillation recurred in the early hospital course. Clinical evaluation found no significant coronary atherosclerosis or structural cardiac disease. One patient is asymptomatic after 2 years; the second patient died suddenly at 4 months; and the third is asymptomatic but had inducible ventricular tachycardia on electrophysiologic testing 6 months after resuscitation. The mechanism of sudden death in young Southeast Asian men appears to be ventricular fibrillation. The cause of the arrhythmia is unclear, although in our patients the arrhythmia was not an isolated event; underlying predispositions to further cardiac arrest persisted.

Adult↗
PubMed1983

Failure of bretylium to suppress inducible ventricular tachycardia.

Five patients with recurrent, life-threatening ventricular arrhythmias were given bretylium tosylate intravenously for a minimum of 4 days. Arrhythmias were not related to acute ischemia in any patient. Four patients had inducible ventricular tachycardia, and one patient had inducible ventricular fibrillation requiring cardioversion while taking no medications. Programmed electrical stimulation was then repeated to assess the ability of bretylium to suppress inducible ventricular tachycardia. Bretylium tosylate, at a mean dose of 2.3 mg intravenously per minute, did not suppress inducible ventricular arrhythmias in any patient. Rapid ventricular tachycardia was induced in all patients, and ventricular fibrillation was induced in one patient. Two patients required external cardioversion to terminate their arrhythmias. Bretylium tosylate, given in relatively large doses chronically, did not suppress inducible ventricular arrhythmias in these five otherwise drug-refractory patients with chronic recurrent ventricular tachycardia. This failure to suppress inducible ventricular arrhythmias cannot be attributed to the initial catecholamine release which occurs in the first hour or two after the drug is administered.

Adult↗
PubMed1983

Prolongation of cardiac refractory times in man by clofilium phosphate, a new antiarrhythmic agent.

The electrophysiologic effects of clofilium phosphate, a new quaternary ammonium antiarrhythmic agent, were evaluated in 15 patients with a variety of cardiac dysrhythmias. Ten patients had ventricular dysrhythmias and five patients had supraventricular dysrhythmias. Clofilium was administered as a single bolus intravenously in doses ranging from 60 to 300 micrograms/kg during electrophysiologic testing. Blood pressure and heart rate were unchanged, and there were no significant side effects. Conduction time was unchanged in atrial tissue, ventricular tissue, atrioventricular node, and in the His-Purkinje system. QT intervals lengthened, atrial effective refractory period increased, and ventricular effective refractory period increased. The effective refractory period of the AV node was unchanged. Refractoriness of the bundle branches or His-Purkinje system was increased in eight patients. Inducible supraventricular arrhythmias were improved in four of four patients, and inducible ventricular arrhythmias were improved in at least five of nine patients. Clofilium is a model for an antiarrhythmic drug which should be useful in interrupting or suppressing reentrant arrhythmias because it increases refractoriness without major changes in conduction time.

Adult↗
PubMed1983

Toxic and therapeutic effects of amiodarone in the treatment of cardiac arrhythmias.

Amiodarone was used to treat cardiac arrhythmias that had been refractory to conventional medical therapy. The first 70 consecutive patients treated with amiodarone in this study had at least 6 months of follow-up (range 6 to 24, mean 11) and form the basis for this report. Sixty-six patients were treated for ventricular arrhythmias and four for supraventricular tachycardias. Amiodarone therapy consisted of a loading dose of 600 mg orally twice a day for 7 days, and 600 mg daily thereafter. Doses were reduced only if side effects occurred. Because of frequent side effects, the dose was reduced from 572 +/- 283 mg per day (mean +/- standard deviation) at 45 days to 372 +/- 174 mg per day at 6 months. With a mean follow-up of 11 months in the 54 patients who continued to take amiodarone, only 4 patients had ventricular fibrillation. Three additional patients experienced recurrent sustained ventricular tachycardia in long-term follow-up. All 70 patients had extensive clinical and laboratory evaluation in follow-up. Side effects were common, occurring in 93% of patients. Thirteen patients (19%) had to discontinue the medication because of severe side effects. Fifty-six patients had gastrointestinal side effects, most commonly constipation. All patients but 1 eventually developed corneal microdeposits, and 43 patients were symptomatic. Cardiovascular side effects were uncommon. Symptomatic pulmonary side effects occurred in seven patients, with unequivocal pulmonary toxicity occurring in five. Neurologic side effects, most commonly tremor and ataxia, occurred in 52 patients. Thyroid dysfunction occurred in 3 patients, and 32 patients had cutaneous abnormalities. Miscellaneous other side effects occurred in 32 patients. Amiodarone appears to be useful in the management of refractory arrhythmias. Because virtually all patients develop side effects when given a maintenance daily dose of 600 mg, lower maintenance doses should be used. It is unknown if the more severe side effects are dose-related. Amiodarone is difficult to administer because of its narrow toxic-therapeutic range and prolonged loading phase. More importantly, the first sign of antiarrhythmic failure may be manifest as sudden cardiac death.

Amiodarone↗
PubMed1982

Evaluation of automated blood pressure measurements during exercise testing.

Measurements of systolic (SBP) and diastolic (DBP) blood pressure were made at rest and during symptom-limited exercise with an automated blood pressure measuring device (EBPM). Comparisons were made between the EBPM readings and those made with mercury manometer. Correlations were high (SBP r = 0.92, DBP r = 0.80) when readings were made in the same arm, but were less satisfactory when the cuffs were on different arms (SBP r = 0.80, DBP r = 0.46). The correlation between two mercury manometer readings was SBP r = 0.90, and DBP r = 0.75. Comparison between EBPM and intra-arterial measurements were similar (SBP r = 0.74, DBP r = 0.79) to comparison between mercury manometer and intra-arterial measurements (SBP r = 0.81, DBP r = 0.61). The EBPM detected SBP at consistently higher levels than did physicians, which may be an advantage in the noisy environment of an exercise test. There was a definite tendency for physicians to record blood pressure to the nearest 10 mm Hg, whereas the frequency distribution curve for EBPM measurements was smoother. The EBPM operated satisfactorily at rest and during maximal exercise and gave as reliable measurements as a physician using a mercury manometer and, in the small number of available cases, detected exertional hypotension more often than the physician.

Blood Pressure↗
PubMed1982

Termination of ventricular tachycardia by programmed extrastimuli from an externally-activated permanent pacemaker.

Two patients with hemodynamically well-tolerated recurrent ventricular tachycardia, drug resistant and previously requiring numerous external electrical cardioversions, had a permanent pacemaker implanted which could be programmed to deliver extrastimuli to convert the ventricular tachycardia to normal sinus rhythm. The patient- or physician-activated device can be programmed to induce or terminate ventricular tachycardia with extrastimuli delivered at the predetermined intervals which consistently induced or terminated the arrhythmia in the electrophysiology laboratory, allowing repeated evaluation of drug regimens. The pacemaker has reliably, painlessly, and consistently induced and terminated repeated episodes of ventricular tachycardia. This programmable pacemaker offers an alternative therapy for patients with hemodynamically well-tolerated refractory ventricular tachycardia.

Aged↗
PubMed1981

Echocardiographic appearance of the Chiari network: differentiation from right-heart pathology.

As echocardiography is being used more often, its value and accuracy are becoming more fully appreciated. Coincident with wider application of this imaging technique is the potential for identifying normal anatomic variants and their possible erroneous interpretation as pathologic states. In this report we describe the M-mode and two-dimensional echocardiographic features of a congenital remnant known as the Chiari network. This structure can present as a highly mobile, highly reflectant echo target that can be seen in several locations in the right atrium. We report here an index case that could be well examined echocardiographically and that was a cause of considerable concern due to the presence of congestive heart failure and a history of staphylococcal endocarditis. The presence of the Chiari network was confirmed pathologically. Subsequently, we found similar echocardiographic findings in 19 of 1248 patients (1.5%) studied in our laboratory. This congenital remnant, which is found pathologically in 2-3% of normal hearts, could be confused with valve disruption, vegetation or other mass lesion, particularly when associated with a suggestive clinical situation.

Adult↗