[Mechanoelectric feedback and sudden death in heart failure]. / Retroalimetación mecanoeléctrica y muerte súbita en insuficiencia cardiaca.

Better knowledge of mechanisms which perpetuate heart failure and promote progression and death in patients with these sicknesses, has led to find a better medical treatment to improve the functional status, decrease mortality and improve life span, avoiding the progression of ventricular dysfunction. Mortality reduction due to the disease progression has led to evident arrhythmic mortality show by sudden death. Aspects involved in the genesis and pathophysiology of sudden death in patients with chronic-heart failure; are reviewed in this paper. Special reference to mechano-electrical feedback is considered.

[Heart catheterization in Mexico. Results of the 1996 census of heart catheterization services by the Mexican Society of Cardiology]. / Cateterismo cardiaco en México: Resultados del censo 1996 de Servicios de Cateterismo Cardiaco por la Sociedad Mexicana de Cardiología.

The findings of the 1996 Cardiac Catheterization Laboratory Survey of the Sociedad Mexicana de Cardiología are presented. There are 52 cardiac catheterization laboratory departments distributed in 16 cities of which Mexico City has 20, Guadalajara 6 and Monterrey 5. Ninety-six percent are in hospitals where heart surgery can be performed and 8 (17%) have a training program in cardiac catheterization. Only two (3.8%) are exclusively dedicated to pediatric cardiac catheterization. In 1995, 19,214 diagnostic procedures and 2,429 PTCAs were done. A total of 270 physicians were reported to have privileges to perform cardiac catheterization. The geographical distribution of the cath labs, procedure volumes and number of physicians performing catheterization are discussed.

[The antihypertensive effect of lisinopril in a single daily dosage. A study of arterial pressure with ambulatory monitoring]. / Efecto antihipertensivo del lisinopril en dosis única diaria. Estudio de presión arterial con monitoreo ambulatorio.

We studied 25 patients with hypertension documented through ambulatory blood pressure monitoring (ABPM) to know the antihypertensive effect of Lisinopril and its action throughout the day. ABPM was done in all patients after two weeks of washout (phase 1). Then patients took 20 mg daily of Lisinopril during four weeks and after that ABPM was repeated (phase 2). Finally, those patients who persisted with high blood pressure received 40 mg daily of Lisinopril during four more weeks and again ABPM was repeated (phase 3). We found statistic difference in the systolic and diastolic blood pressure among the three phases. During the first phase there were 17 patients (68%) with high blood pressure and this number decreased to 8 (32%) in the second one and to 7 (28%) in the third phase. The results show that Lisinopril has satisfactory antihypertensive effect in about 40% of patients. Nevertheless 20% of the case remained with high blood pressure despite treatment with 40 mg of Lisinopril. On the other hand, both, systolic and diastolic blood pressure decreased satisfactory during the night with the dosage received in the morning. We concluded that Lisinopril has moderate effect when it is given as monotherapy and, it has satisfactory effect all over the day.

[Diagnosis of myocardial ischemia by dynamic digital echocardiography with dobutamine and atropine]. / Diagnóstico de la isquemia miocárdica mediante ecocardiograma dinámico digitalizado con dobutamina y atropina.

We studied 300 patients (p) with dobutamine stress echocardiography (DSE) and atropine. The indication were chest pain, abnormal electrocardiogram (ECG), abnormal stress electrocardiogram with or without chest pain or any combination of these. The DSE was evaluated with digitized imaging in long and short parasternal views and apical four and two chambers views before and during dobutamine test with simultaneous side by side display. In 21 p (56.7%) we found positive concordance in diagnosis of coronary artery disease (CAD) between coronary arteriography (CA) and DSE. In 13 of 37 p the concordance was negative by the two methods (35.1%); then the DSE was capable correctly predict in 34 p (91%). The abnormal CA and normal DSE were found in one p (4.5%) with 90% obstruction of a small diagonal vessel. In two women DSE was abnormal with inferior hypokinesis (13.3%) and the CA was normal. In 43 p (14.3%) ECG and DSE were positive for myocardial ischemia (MI); negative concordance of both procedures was found in 203 p (67.6%). ECG was abnormal and DSE normal in 46 p (15.3%) 61 p (20.3%) with DSE abnormal in 8 p (2.6%) 61 p (20.3%) had arrhythmias; in 55 (18.3%) premature ventricular contractions, one p with ventricular tachycardia (0.33%); 7.3% of them required endovenous lidocaine. Chest pain was present in 22 p (7.3%) and the treatment waqs sublingual isosorbide; hypotension appeared in 27 p (9%) and were treated with saline infusion. Hypertensive response was found in two p (0.66%) and were treated with nifedipine and smolol. We concluded that DSE with atropine has high sensibility (95.5%) and specificity (86.6%) in the diagnosis of ischemic heart disease. The adverse effects are nondangerous and easily resolved with medical treatment.

[The mechanism of remodelling in left ventricular volume overload]. / El mecanismo de remodelación en las sobrecargas de volumen del ventrículo izquierdo.

We studied 60 people who were separated into three groups. Group A: 11 patients with pure, severe mitral regurgitation (MR); Group B: 18 patients with pure, severe aortic regurgitation (AR) [this group was divided into two: I) with normal ejection fraction (EF) and II) with low EF]. The third group was a control one with 31 healthy people. Through 2-D Echocardiography (2-D Echo) we got: diameters of the cavities, thickness of the wall, ventricular function, h/r ratio, and systolic wall stress (S). Patients with MR showed left atrial and ventricular enlargement with low h/r ratio, normal ventricular function and raised S. The group I of AR had left ventricular enlargement and hypertrophy, with normal h/r ratio and EF, and with raised S, while the group II of AR showed left ventricular enlargement, low h/r ratio and EF with very high S. In MR volumetric overload causes different anatomic and functional changes on the left ventricle than in the AR. In MR there is a systolic leak toward left atrium. This causes the low S in the beginning of the illness and is not the mechanism that trigger left ventricular hypertrophy (LVH). The absence of LVH causes excessive enlargement of the myofibril and with time there is structural damage and contractile failure which raises the systolic volume and S. Later on, hypertrophy develops. On the other hand, since the beginning AR has high S which causes adequate hypertrophy (normal h/r ratio) and later it produces huge ventricular enlargement decreases the h/r ratio (inadequate hypertrophy) with contractile failure. We conclude: the time of surgery in MR is when the patient raises S and in the AR when inadequate hypertrophy appears (low h/r) but when EF is still normal.

[Structural and functional changes in the heart of the hypertensive patient. An echocardiographic study]. / Cambios estructurales y funcionales en el corazón del hipertenso. Estudio ecocardiográfico.

We studied 15 patients with essential hypertension (EH) in whom the diagnosis was corroborated with ambulatory blood pressure monitoring (ABPM). The blood pressure levels (BP) were compared with values obtained from healthy people (HP). We studied 31 HP with 2-D echocardiogram and the parameters of ventricular performance were compared with the values obtained from EH people. ABPM shown that the EH people has higher BP values than HP around 24 hs (EH loss the circadian rhythm of BP). On the other hand the EH had left ventricular hypertrophy (LVH) with normal systolic ventricular function (VF). The systolic wall stress was low because the LVH was inappropriate. The LVH as adaptative mechanism maintains normal the VF in spite of pressure overload without increasing MVO2. When the pressure overload is not eradicated in a variable amount of time the adaptative mechanisms slowly change to a pathologic process caused by collagen deposition in the interstitium of the heart. In advanced stages the remodeling process causes diastolic disfunction, myocardial ischemia, arrhythmias and death by heart failure or suddenly. This last stage is the real hypertensive heart disease.

[Effect of transdermal therapy with clonidine on suppression symptoms secondary to smoking cessation]. / Efecto de la terapia transdérmica con clonidina en los síntomas de suppresión secundarios al cese del consumo de tabaco.

For the purpose of evaluating the effectiveness of transdermal clonidine treatment (Catapres-TTS No. 2) on ameliorating withdrawal symptoms associated with smoking cessation, we carried out a prospective study on 375 patients who smoke, motivated to abandon smoking. Each patient acted as his own control at one moment receiving placebo and, at another, clonidine. Each patient was instructed to maintain his normal daily cigarette consumption during the first three days of study, and to stop smoking from the fourth to the seventh day. All of the withdrawal symptoms measured (craving, irritability, anxiety and restlessness) significantly increased (p = 0.001) in the placebo group during the days of abstinence. There was a 5 fold increase in craving and in irritability, in the placebo group, as compared with the transdermal clonidine group during the three days of smoking cessation. Anxiety and restlessness also augmented at 3 times greater extent. Regarding the side effects, these were slight and of a transitory nature. Transdermal clonidine treatment helps the heavy smoker to give up tobacco by means of a considerable drop of the short-term withdrawal symptoms, specially craving and irritability, associated with smoking cessation.

[Infectious endocarditis in a healthy valve, arising from another valve]. / Endocarditis infecciosa en una válvula sana, condicionada por otra enferma.

We report a case of isolated aortic regurgitation complicated by active infective endocarditis with streptococcus viridans as causative organism. The affected structure was a previous normal mitral valve.

[The P wave in systemic arterial hypertension. Comparison with the echocardiogram and apexcardiogram]. / La onda P en la hipertensión arterial sistémica. Correlación con el ecocardiograma y el apexcardiograma.

The cause of an abnormal electrocardiographic P wave (AEPW) in systemic arterial hypertension (SAH) has not been delucidated. In order to demonstrate if this sign is related to volume overload of the left atrial cavity -previously we found no correlation between pressure overload of the cavity and the presence of an AEPW- 34 patients with SAH were studied; population were divided in two groups: group A (GA, n = 13), formed by 13 cases with a P wave more than 0.10 s duration (D2 standard lead) and group B integrated by 21 cases with a P wave at 0.10 s or less duration. In each cases phonocardiographic and echocardiographic (Mode M) studies were performed and the following data were obtained: "A" index (AI), left atrial dimension (LAD) and, septal (SD) and left posterior wall dimension (LPWD); besides: Sokolow electrocardiographic index (SI) and systolic (SBP) and diastolic (DBP) blood pressure. Results are shown in the following table: (Table: see text). There were not statistical differences between groups (data of SBP and DBP not shown). Correlation between LAD and AI and duration of P wave were not statistical different (data not shown). An AEPW in SAH does not seem to be cause by a volume left atrial overload. Possible it is related to an interatrial conduction defect.

Estenosis aórtica calcificada: semiología y aspectos diagnósticos no invasivos en el anciano / Calcified aortic stenosis: clinical and non-invasive diagnostic aspects in the eldery patient

La estenosis aórtica (EAo) en el anciano es un problema relativamente frecuente y de semiología diferente a la del paciente joven. En este trabajo se estudió la semiología de la EAo en el anciano y se buscaron los hallazgos que los métodos no invasivos ofrecen para su diagnóstico cuali y cuantitativo. Efectuamos un análisis retrospectivo en 23 pacientes de más de 60 años de edad, con diagnóstico de EAo calcificada establecido por hemodinámica. Demostramos que la calcificación de la válvula aórtica en la radiografía del tórax, el período expulsivo (PE), la morfología del pulso carotídeo y el espesor de las paredes ventriculares en el estudio ecocardiográfico con signos muy útiles para asegurar el diagnóstico cualitativo. La presencia del síncope, la ubicación del soplo en la mesotelesístole, la presencia de desdoblamiento paradójico del segundo ruído y la prolongación del PE a más de 110%, significan un gradiente transaórtico mayor de 50 mmHg. Concluimos que el cateterismo cardíaco diagnóstico sólamente está indicado en casos aislados