Raul Chirife

Preclinical cardiac malfunction in chronic alcoholism. Comparison with matched normal controls and with alcoholic cardiomyopathy.

Abstract To determine whether cardiac malfunction in chronic alcoholics precedes clinical signs of cardiac damage, noninvasive polygraphic recordings were carried out and interpreted independently in 26 ambulatory patients with chronic alcoholism and no clinical evidence of heart disease, normal control subjects matched for age and sex, and 12 patients with alcoholic cardiomyopathy. Heart rates were significantly elevated in the alcoholic patients and the patients with cardiomyopathy. Blood pressures tended to be lower in both the alcoholic and cardiomyopathy groups, but significantly different only between the cardiomyopathy and normal groups. Preejection period (PEP), left ventricular ejection time index (LVETI) and the ratio PEP/LVET were markedly abnormal in both the alcoholic and cardiomyopathy groups. Electromechanical systole index (EMSI) was statistically the same in all three groups. All abnormalities in the clinically normal alcoholic patients were in the direction of depressed myocardial functi...

Ejection Time by Ear Densitogram and Its Derivative: Clinical and Physiologic Applications

Ear densitographic ejection times (EDET) and first derivative ear densitogram ejection times (dEDET) were studied to determine whether their reliability and validity justify their substitution for ejection times derived from the far less stable carotid pulse tracing. Inter- and intra-subject comparisons were made on thirty individuals under a wide variety of disease and challenge states. Statistical analysis of the data-which had been obtained through a blinded procedure-showed an overall correlation (r) of .98 for carotid vs EDET and .99 for carotid vs dEDET. The t-test demonstrated no significant differences among ejection times derived from the three methods. Moreover, the close tracking at rest and during challenges of ejection times derived from these curves with those from the carotid indicate that either method may be substituted for standard carotid curves without sacrificing reliability or validity of the measure. Both ear curves offer distinct advantages over carotid pulse curves because their sensor is self-retaining and they remain stable during exercise and other body and respiratory movements. The additional feature of simplicity in reading the first derivative of the ear densitogram over its undifferentiated curve makes dEDET the preferred method.

Densitography: A new method for evaluation of cardiac performance at rest and during exercise☆

Abstract Pulse tracings reflecting the cyclic variations in translucency of the tissues of the pinna of the ear (densitograms) were obtained by means of a photoelectric device in 26 subjects, nine of whom were free of cardiovascular disease, and in two normal subjects during exercise in the upright position. Ejection periods were calculated from the densitographic tracings using the technique of extrapolation for damped pulse curves previously reported and statistically compared to the ejection periods (LVETs) determined conventionally from the simultaneously obtained carotid pulse tracings. The over-all correlation of carotid- and densitogram-derived LVETs was 0.97, with no statistically significant difference in any of the categories of patients studied. Of the 26 subjects recorded at rest, 24 were in sinus rhythm, and in these the correlation coefficient was found to be the highest ( r = 0.99). In the exercised subjects the correlation was somewhat lower ( r = 0.82) due to wider dispersion of carotidderived LVETs because of errors in measurement caused by motion artifacts. In the two patients with atrial fibrillation, measurements of the relative amplitudes of the densitographic curve were compared on a beat-to-beat basis with the LVETs of the corresponding beats. There was a high degree of correlation in both cases ( r = 0.96 and r = 0.84). We conclude that densitograms are an excellent substitute for the carotid pulse tracing for measuring time-based intervals of the cardiac cycle and they are the curve of choice to be obtained in noninvasive studies during exercise. Changes in densitogram amplitude and LVET are mutually predictable in the same individual.

Measurement of the left ventricular ejection time by digital plethysmography

Abstract A blinded, multiple-observer comparison of ejection periods obtained from simultaneous carotid pulse tracings and digital plethysmograms was made in 10 healthy volunteers. The technique for measuring the left ventricular ejection time from the plethysmographic curve consists of the extrapolation of the rapid ascent toward the base line to obtain the upstroke point ( u ) and extrapolation of the rapid descent, preceding the dicrotic notch, to obtain the d point, analogous to the carotid incisura. A high degree of correlation with a high reciprocal predictability was found for both methods of obtaining the ejection time. The mean value of peripheral pulse transmission velocity was found to be in close agreement with those obtained by other investigators.

Automatic beat-to-beat left heart AV normalization: Is it possible?

Programming the right heart AV interval to a normal value may cause a nonphysiological left heart AV due to interatrial and interventricular conduction delays, thus affecting cardiac performance. Since AV normalization at rest and exercise may be invalidated by pacing or sensing (mode) changes, the aim of this study was to (1) study the feasibility of a mode independent pacemaker (PM) algorithm for automatic beat‐to‐beat left AV normalization, (2) establish normal values for the time between mitral flow A wave (Af) and ventricular activation (Va), the AfVa interval, the mechanical surrogate of left AV, and (C) determine the range of values of the interatrial electromechanical delays (IAEMDs) and the effect of RA pacing. To pace with the proper right AV, the previously reported RV‐paced interventricular electromechanical delay and the interatrial electromechanical delay, either P‐sensed (IAEMDs) or atrial‐paced (IAEMDp) are required inputs. Data were collected during diagnostic echo Doppler studies in 84 subjects divided in three groups: (1) control with narrow QRS and no structural heart disease (n = 33, age 50 ± 21 years, 42% men); (2) patients in sinus rhythm with diverse cardiac pathologies except LBBB (n = 39, age 69 ± 14 years, 56% men), and (3) DDD‐paced patients (n = 12, mean age 71 ± 6 years). Normal values of AfVa were established from the control group, while IAEMDs and IAEMDp and active atrial flow time (A‐peak), in all subjects. The algorithm was tested by computer simulation under all possible modes with the following calculation: RAV = N + IAEMD − IVD, where RAV is the right AV, N is the desired normal AfVa value, IAEMD is either P‐sensed or A‐paced, and IVD is close to zero for intrinsic narrow QRS and biventricular pacing, or 79 ms for RV pacing. The results demonstrated (1) Normal (controls) AfVa: 85 ± 15 ms (range 52–110 ms); (2) IAEMDs (All): 84 ± 16 ms; (3) atrial pacing prolonged IAEMDs by 57 ± 18 ms (from 93 ± 15 to 150 ± 25 ms, P < 0.0001); and (4) Computer simulation of rate and mode changes validated the normalization algorithm. An automatic, beat‐to‐beat left AV normalization algorithm to preserve a normal AfVa without a hemodynamic sensor is feasible. The normal value of AfVa is 85 ± 15 ms. (PACE 2003; 26:2103–2110)

Insulin sensitivity in young women with vasovagal syncope.

BACKGROUND Insulin, in addition to its known metabolic effects, has sympatho-excitatory and vasodilatory actions on muscular blood vessels. The goal of this study was to evaluate insulin sensitivity in young women with vasovagal syncope and positive tilt test results (HUT+) and to compare it with that in patients with negative tilt test results (HUT-) and in control subjects without a history of syncope. METHODS Different indices of insulin sensitivity were obtained by an oral glucose tolerance test (OGTT) in 13 young women with syncope and HUT+ (age 26.8 +/- 9.1 years, body mass index 20.4 +/- 2.1), 8 patients with HUT- (age 26 +/- 5.6 years, body mass index 21.9 +/- 2.4), and 13 control subjects without syncope and HUT- (age 28.9 +/- 8.8 years, body mass index 23.1 +/- 1.7). The following parameters were assessed: fasting glucose and insulin levels (G(0), I(0)); G(0)/I(0) ratio; G(0) x I(0); areas under the curve for glucose and insulin; homeostatic model assessment (HOMA); quantitative insulin sensitivity check index (QUICKI); and composite whole-body insulin sensitivity index (ISI). RESULTS G(0) and I(0) values were significantly lower in patients with HUT+ than in control subjects (G(0) 4.9 vs 81.9, P <.05, I(0) 4.7 vs 9.1, P <.005). All the fasting values-based indices (ie, HOMA 0.9 vs 1.9, P <.005) and the ISI (12.8 vs 7.1, P =.01) differed significantly in both groups. None of the parameters showed significant differences between patients with HUT- and control subjects. Sixty-one percent of patients with HUT+ had a vasovagal reaction during OGTT. CONCLUSIONS Young women with vasovagal syncope and HUT+ have a greater insulin sensitivity. They have a propensity to reproduce symptoms during the OGTT. This hypersensitivity could be one of the predisposing factors for vasovagal episodes.

Role of nitric oxide in young patients with vasovagal syncope

AIMS Nitric oxide (NO) formed in the vascular endothelium produces, among other effects, a strong vasodilation. In order to evaluate the possible role of NO in hypotension induced by head-up tilt test (HUT), we measured plasma levels of its metabolites, nitrites and nitrates (NOx), during the test. METHODS AND RESULTS Twelve patients with vasovagal syncope and positive HUT [HUT(+)] (mean age: 23+/-5 years) and 13 healthy volunteers with negative HUT (controls) (mean age: 24+/-5 years) were included. Venous blood samples were obtained during the baseline stage for biochemical measurements. Plasma values of NOx were obtained under baseline conditions (T0), at the end of the HUT (T1), and 15 min after the end of the HUT (T2). The baseline biochemical values as well as haemodynamic parameters were similar in HUT(+) patients and controls. NOx plasma values (in micromol/L) were as follows [HUT(+) vs. controls]: T0: 5.7+/-1.6 vs. 8.8+/-4.7 (P=0.05), T1: 6.1+/-3.2 vs. 8.5+/-3.6 (P=NS), and T2: 6.1+/-3 vs. 10.2+/-8.9 (P=NS). The NOx levels were directly correlated with the insulin levels (Spearmans R=0.53, P=0.008). CONCLUSION Baseline plasma levels of NOx were significantly lower in HUT(+) patients than in controls. However, since the expected increase in NOx values during HUT-induced syncope was not observed, the possible role of NO in vasovagal hypotension is uncertain.

Left Ventricular Ejection Time by Densitometry in Patients at Rest and During Exercise, Atrial Pacing and Atrial Fibrillation Comparison with Central Aortic Pressure Measurements

A comparison of left ventricular ejection time (LVET) measured directly from the central aortic pressure tracing (CAPT) and a densitogram recording was carried out in 39 patients during diagnostic cardiac catheterization. The correlation coefficient between the LVET derived from the CAPT and densitogram of 32 patients while at rest was 0.974 with a standard deviation from regression (SDR) of 6.2 msec. Sequential LVETs were analyzed in two patients during atrial pacing, three patients during exercise and three patients with atrial fibrillation. Correlation coefficients were 0.981, 0.951 and 0.974 with SDRS of 5.3, 6.2 and 6.7 msec respectively. Assuming LVET from the CAPT to be error free, the over-all error of estimating LVET by densitogram was less than 5% for over 95% of the measurements. The largest mean difference between CAPT and densitogram derived LVETs was present during atrial pacing and corresponds to an error of less than 2% of the average LVET for the group. We conclude that densitometry is a practical and reliable noninvasive method for LVET measurements in a variety of physiological and pathological conditions.

The systolic index: a noninvasive approach for the assessment of cardiac function: implications for patients with DDD and CRT devices.

Our objective was to evaluate the systolic index (SI), the ratio between rate‐corrected left ventricular ejection time (LVETc), and a preejection period surrogate (PEPsu), to assess cardiac function in patients with DDD and cardiac resynchronization therapy (CRT) pacemakers.

Symptomatic, Inspiration-Induced Atrioventricular Block: Treated with Pacemaker Implant: SYMPTOMATIC, INSPIRATION-INDUCED ATRIOVENTRICULAR BLOCK

The respiratory sinus arrhythmia is the most common cardiac arrhythmia. It consists of phasic variations of sinus cycle length produced by an autonomic reflex, and is characterized by increased heart rate during inspiration and decline in expiration. This phenomenon is due to a reduction of the parasympathetic tone during inspiration, causing a rise in the heart rate, while during expiration the opposite phenomenon occurs. This arrhythmia is more frequent in young adults, although it can also be seen in any age group.