BACKGROUND: During atrial contraction, the left atrium produces both forward ejection to the left ventricle and backward ejection to pulmonary veins. PURPOSE: To determine quantitatively left atrial ejection performance in symptomatic hypertrophic cardiomyopathy (HCM) patients by using left atrial systolic time intervals. METHOD: Thirty-one patients with symptomatic HCM and sinus rhythm and 31 normal subjects were studied with transthoracic and transesophageal Doppler echocardiography. Left atrial pre-ejection period (APEP), corrected atrial pre-ejection period (APEPc), and the duration (AET) and the time velocity integral (IA) of the atrial contraction wave in transmitral flow were determined. The duration (PV-AET) and the time velocity integral (PV-IA) of reverse pulmonary venous flow during atrial contraction were also determined. RESULTS: For normal subjects, significant correlations were found between APEP and electrocardiographic P wave duration (r=0.78, p<0.001), and between APEPc and left atrial forward ejection indices (AET: r=-0.42, p=0.01, IA: r=-0.54, p<0.05, respectively), but not between APEP and either of the two latter indices. These findings indicate that, for normal subjects, APEPc is a better index of left atrial systolic function than APEP. In contrast, for HCM patients, significant correlations were found between APEPc and left atrial backward ejection indices (PV-AET: r=-0.49; p<0.005, PV-IA: r=-0.66; p<0.001, respectively), but not between APEPc and left atrial forward ejection indices. CONCLUSION: Augmentation of left atrial afterload may result in decreased left atrial forward ejection and increased left atrial backward ejection. Thus, both left atrial forward ejection and left atrial backward ejection must be considered in the assessment of left atrial ejection performance in patients with symptomatic HCM.

View full abstract

To clarify the effect of atrial fibrillation (AF) on the fibrino-coagulation system, fibrino-coagulation parameters in the paroxysmal period of AF were determined in 13 patients with paroxysmal atrial fibrillation (PAF) and compared with those in the non-paroxysmal period of AF, and with those in normal subjects. Estimated titers of hemoglobin and hematocrit in the paroxysmal period of AF were significantly higher than those in the non-paroxysmal period and also higher than those in normal subjects. The activated partial thromboplastin time in the paroxysmal period was also longer than that in the non-paroxysmal period of AF or in normal subjects. However, other estimated parameters, such as prothrombin time, fibrinogen, thrombin-antithrombin III, β-thromboglobulin, platelet factor 4, D-dimer and plasmin inhibitor complex, did not show any significant deviation. These results conflict with those of previous reports which indicated that the fibrino-coagulation system was enhanced in cases of chronic AF. Our results suggest that there is no significant activation of the fibrino-coagulation system, except for obvious hemoconcentration, within the first few hours after the onset of PAF. Thus, in terms of the properties of blood coagulation, thromboembolism is preventable if antiarrhythmic therapy is administered within several hours after the onset of PAF.

View full abstract

We operated on 20 adult patients with ventricular septal defect (VSD). In 7 of these cases (aged 36 to 51 years, average 42.6 years), VSD was accompanied by sequelae other than pulmonary hypertension. Concomitant procedures in type-I VSD included a suspension of the prolapsed aortic cusp in 2 patients, a repair of the ruptured sinus of Valsalva in 2, and a new procedure for active infective endocarditis, described below, in 2. In this latter procedure, the aortic valve and infected Valsalva sinus were excised, and the pulmonary valve and the right ventricular wall to which the infection had extended were thoroughly debrided. The resulting defect was closed with a single patch, and a prosthetic valve was inserted in the position of the original aortic valve using this patch as part of the annulus. Another patient with the type-II VSD underwent concomitant tricuspid valve replacement for infective endocarditis. In the mean follow-up period of 77.1 months, 6 patients have been doing well in New York Heart Association class I, and the remaining patient with Valsalva repair remained in class II due to dilated cardiomyopathy.

View full abstract

Eighty-five coronary artery patients examined using an ambulatory electrocardiogram-respiration monitoring system (AERMS) in which a respiratory sensor was strapped to the right upper abdominal wall. Apnea was defined as a cessation of abdominal wall movement lasting at least 10 sec. Sleep-related breathing disorder (SRBD) was diagnosed if at least 30 apneic episodes were observed during sleep. The cardiac events evaluated during follow-up included occurrence of sudden death, myocardial infarction and ventricular tachycardia. SRBD was detected in 9 of 85 patients (11%). There were more patients with low EF (EF<50%) in the SRBD group than in the non-SRBD group (p<0.01). During follow-up for a mean period of 18.4±7.6 months after ambulatory recording, four of nine (44%) patients in the SRBD group had cardiac events, compared with only four of 79 (6%) patients in the non-SRBD group (p<0.001) . Thus, coronary artery patients who were complicated with SRBD showed poor cardiac function and had a high incidence of cardiac events.

View full abstract

Steroid hormones are thought to have a positive inotropic action, but the precise electrophysiological effects which underlie this positive inotropism remain unknown. The effects of hydrocortisone on the L-type calcium current (I_Ca) of the isolated guinea pig ventricular cells were investigated under the whole-cell voltage-clamp recording. Hydrocortisone (10^-6 to 10^-5 M) increased the amplitude of I_Ca without any changes in the voltage-dependency in I_Ca. This agent retarded the fast inactivation component of I_Ca, but not the slow component. On the other hand, hydrocortisone slightly reduced the slope conductance of inward rectifying potassium current (I_K1) at potentials less than -50 mV. This effect on I_K1 is favorable for the activation of I_Ca. Thus, these results indicate that the positive inotropism of hydrocortisone is mediated, at least in part, by a direct potentiating effect on I_Ca.

View full abstract

The effects of alacepril, an angiotensin converting enzyme inhibitor, on atherogenesis were examined in rabbits fed a hypercholesterol diet. The process of atherogenesis was evaluated in vitro by high-resolution transesophageal ultra-sonography (TEE &emptyv;4 mm, 7.5 MHz), by direct histological examination and by serum lipid examination. Of the 38 subjects, 18 were designated as the control hypercholesterol group (CH) and 20 received oral alacepril at 90 mg/day (ACE) for 13-22 weeks. Three rabbits in each group died due to pneumonia. TEE enabled a clear diagnosis as either normal, early stage or late stage of atherosclerosis. The intimal-medial thickness was significantly less in the ACE group than in the CH group, but only over the middle portion of the aorta. The ACE group had a smaller area of atheromatous plaque than the CH group (atheromatous index: 37±20* and 60±30% respectively, *p<0.02). Serum cholesterol and triglycerides were similar in the CH group (1590±653, 258±224) and the ACE group (1574±824, 303±360 respectively). In conclusion, alacepril reduced both the area of atheromatous atheroma plaque and wall hypertrophy independent of serum lipids in cholesterol-fed rabbits. In vitro miniature TEE is a dependable method for evaluating atherosclerosis in rabbits with hypercholesterolemia.

View full abstract

We investigated the changes in the membranous β-adrenoceptor-adenylate cyclase system in the right ventricle, left ventricle and interventricular septum during the progress of monocrotaline-induced right ventricular hypertrophy and failure. Theβ-adrenoceptor density was decreased in hypertrophied right ventricle 2 to 4 weeks after treatment. When the rats showed symptoms of right ventricular failure 4 weeks after treatment, theβ-adrenoceptor density was decreased in the interventricular septum. Both basal and forskolin-stimulated adenylate cyclase activities were decreased in the right ventricle at 3 and 4 weeks, and in the interventricular septum at 4 weeks, after treatment, which indicates that the catalytic activity of adenylate cyclase is reduced. Changes in isoproterenol plus Gpp (NH) p- or sodium fluoride-stimulated adenylate cyclase activity were generally similar to those in basal activity. These data indicate that a chamber-specific decrease inβ-adrenoceptor density begins in the early stages of right ventricular hypertrophy, and thatβ-adrenoceptor density and adenylate cyclase activity in the interventricular septum are decreased in the advanced stages of heart failure in monocrotaline-treated rats.

View full abstract