American heart journal
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American heart journal · May 1988
Aortic and right atrial systolic pressures during cardiopulmonary resuscitation: a potential indicator of the mechanism of blood flow.
The absolute difference between aortic and right atrial systolic pressure (systolic pressure gradient) and the difference between the aortic diastolic and right atrial diastolic pressure (coronary perfusion pressure) were evaluated in a series of 63 adult mongrel dogs undergoing five different methods of cardiopulmonary resuscitation (CPR). Fluid-filled pressure monitoring catheters were placed in the ascending aorta and right atrium in each of the animals after induction of anesthesia with morphine sulfate and 1% halothane and oxygen. The animals were then fibrillated with a transvenous electrode catheter that had been introduced into a ventricle. ⋯ The systolic pressure gradient and coronary perfusion pressure were measured in all animals 1 minute after CPR was begun, and in all but the group undergoing open-chest cardiac massage after 7 minutes and 17 minutes of CPR. The systolic pressure gradient and coronary perfusion pressure were greatest during open-chest cardiac massage (true cardiac compression), intermediate in external mechanical CPR (Thumper) and standard CPR (greater in small dogs than large dogs), and lowest in CPR performed with a combined thoracic and abdominal vest apparatus (predominantly thoracic pump). The observation that the systolic pressure gradient between intrathoracic chambers is largest in open-chest cardiac massage and smallest in vest CPR suggests that similar measurements recorded during the performance of human cardiac resuscitation may be useful in determining the mechanism of blood flow.
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American heart journal · Apr 1988
Randomized Controlled Trial Comparative Study Clinical TrialIntravenous lorcainide for symptomatic ventricular tachyarrhythmias: comparison with lidocaine and oral lorcainide.
Intravenous lorcainide and lidocaine were administered to 25 patients with symptomatic ventricular tachyarrhythmias in a randomized single-blind crossover study. Prior to drug therapy, each patient underwent 48 hours of ambulatory monitoring and exercise testing on a motorized treadmill. At the completion of baseline studies, patients were randomized to receive either lidocaine or lorcainide intravenously. ⋯ The oral drug was effective in nine patients (53%), five of whom had responded to the intravenous drug, and was ineffective in eight, seven of whom were also unresponsive to intravenous lorcainide. The intravenous drug predicted the response to the oral form in 71% of patients, but this was not statistically significant. Side effects occurred in 10 patients (59%) and were primarily neurologic.(ABSTRACT TRUNCATED AT 250 WORDS)
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American heart journal · Mar 1988
Comparative StudyA practical application of Doppler echocardiography for the assessment of severity of aortic stenosis.
This study evaluated a strategy that makes optimal use of Doppler echocardiography for estimating the severity of valvular aortic stenosis (AS). Fifty-eight patients with no more than moderate aortic insufficiency who underwent cardiac catheterization were evaluated with two-dimensional echocardiography and Doppler velocimetry to determine the peak velocity across the stenotic valve and aortic valve area (AVA) by means of the continuity equation. All 33 peak Doppler velocities of greater than or equal to 4 m/sec had critical AS (AVA less than or equal to 0.8 cm2 at catheterization). ⋯ Doppler velocity alone was inadequate in determining severity of AS for patients with velocities between 3 and 4 m/sec. The continuity equation proved accurate in estimating AVA in the 46 patients for whom catheterization and ultrasound data were sufficient to compare calculated AVA (r = 0.81), and was also accurate for those patients with peak Doppler velocities between 3 and 4 m/sec (r = 0.90). These results suggest that Doppler velocimetry alone is adequate in determining critical vs noncritical AS in many patients, while the continuity equation should be applied for patients with peak velocities between 3 and 4 m/sec as well as in patients with severely depressed cardiac function.
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American heart journal · Jan 1988
Evaluation of Björk-Shiley prosthetic valves by real-time two-dimensional Doppler echocardiographic flow mapping.
We studied the value of two-dimensional Doppler echocardiographic color flow mapping for identifying normal transvalve flow profiles and valve malfunction in 20 patients with Björk-Shiley prosthetic valves. Seven patients had Björk-Shiley prosthetic valves in the aortic position alone, seven in the mitral position, and six had prosthetic valves in both the aortic and mitral positions. In 10 patients with normally functioning mitral valves, the ratios of the maximal major and minor Doppler-imaged orifice flow diameters to the valve ring diameters were 25 +/- 3% (mean +/- SD) and 24 +/- 3%, respectively, similar to values reported in in vitro studies. ⋯ These included one case of focal fibrous ingrowth involving primarily the minor orifice of a mitral prosthetic valve, one case of mitral valve prosthetic thrombosis with decreased major and minor orifice flow diameters and valvular regurgitation, and four cases of paravalvular regurgitation involving prosthetic valves in the aortic position (three patients) and the mitral position (one patient). Two-dimensional Doppler echocardiographic flow mapping provides new observations that may aid in identifying Björk-Shiley prosthetic valve malfunction. By localizing precisely the site of prosthetic stenosis or regurgitation, it may also assist in defining the cause of valve malfunction.
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American heart journal · Jan 1988
Prevalence and clinical correlates of non-Wenckebach, narrow-complex second-degree atrioventricular block detected by ambulatory ECG.
Among 113 patients with transient, narrow-complex second-degree atrioventricular (AV) block detected by ambulatory ECG, there were 20 with non-Wenckebach behavior. Based on the presence or absence of PR interval shortening after single blocked complexes, patients with narrow-complex non-Wenckebach patterns could be separated into a pseudo-Mobitz II group of 16 patients (greater than or equal to 20 msec of PR shortening after the blocked complex) and a classic Mobitz II group of four patients (constant PR interval). These groups had additional distinct ECG and clinical features. ⋯ Syncope was the presenting symptom in 38% of patients with pseudo-Mobitz II block and in all patients with classic Mobitz II block. Patients with pseudo-Mobitz II block had a 56% prevalence of associated coronary disease and a 44% prevalence of congestive heart failure; the mortality rate was 38% in this group over 4 years of follow-up, but in all instances death was due to associated disease rather than to conduction itself. In contrast, patients with classic Mobitz II block had hypertensive or valvular disease but no evidence of coronary disease or congestive failure; all are alive with pacemakers after 3 years of follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)