Power spectral analysis of heart rate variability during helium pneumoperitoneum: The mechanism of increased cardiac sympathetic activity and its clinical significance.

BACKGROUND: Carbon dioxide pneumoperitoneum (PP) is known to induce increased cardiac sympathetic expression. The role of the insufflated gas involved in this mechanism should be elucidated in an attempt to eliminate its possible serious consequences. METHODS: Twenty-five patients undergoing elective laparoscopic cholecystectomy were prospectively analyzed for cardiac autonomic nervous activity by spectral heart rate variability. In 15 patients, helium was used as CO(2) substitution for abdominal insufflation (study group). Four frequency bands of interest were obtained from the power spectrum of R-R intervals, as well as the ratio between the low and high frequency (LF/HF), using the fast Fourier transformation algorithm to characterize the synergy of both autonomic branches during PP. RESULTS: Significantly increased values of the power spectrum related to the LF and VLF bands (from 130 to 377 msec(2)/Hz and from 145 to 516 msec(2)/Hz, respectively) were inspected during CO(2) PP, as well as increased LF/LH ratio (2.1). Using helium as CO(2) substitution has eliminated the significant changes in the power spectrum that reflect increased cardiac sympathetic activity. CONCLUSIONS: The elimination of sympathetic predominance by helium PP indicates the central role of CO(2) in establishing this phenomena. Considering this information and its other known advantages, helium should be considered for use during prolonged laparoscopic procedures for high-risk patients.

Power spectral analysis of heart rate variability during positive pressure pneumoperitoneum: the significance of increased cardiac sympathetic expression.

BACKGROUND: Positive pressure pneumoperitoneum (PPP) effects on the autonomic nervous system (ANS) might be of clinical importance, as imbalance in the autonomic cardiac control might lead to serious consequences. METHODS: Fifteen healthy patients undergoing elective laparoscopic cholecystectomy were analyzed for cardiac autonomic nervous activity by spectral heart rate variability, during awake state, before and after intubation, during CO2 PPP (14 mmHg), and after CO2 evacuation. The very low, low, high and very high frequency (VLF, LF, HF, VHF respectively) bands of the spectral density of the heart rate variability (HRV) and their normalized values, as well as the LF/HF ratio, were obtained from the power spectra of R-R intervals, using the fast-Fourier transformation algorithm. RESULTS: Using Friedman's nonparametric test, only the difference between the power of LF during anesthesia (median 30.74) and the middle of PPP (median 195.66) was found to be significant (p<0.012). Such change was recorded in 14 patients (p = 0.001, sign test). CONCLUSIONS: Increased LF power reflects sympathetic cardiac activation. As the LF range accounts for regulation of blood pressure and baroreflex, several mechanisms may explain this activation. This in turn may predispose patients who suffer from cardiac disease to higher risk of developing ventricular arrhythmias, besides the possible adverse hemodynamic consequences of PPP.

Breast Hematoma Complicating Thrombolytic Therapy.

Thrombolytic therapy (TT) is now established as the main treatment of acute myocardial infarction (MI). Spontaneous breast hematoma, usually a rare complication of anticoagulant therapy, has been described in the last five decades, but not after thrombolytic therapy. We present three patients who developed the rare complication of breast hematoma after TT, out of 495 women treated with TT in ICCU in our hospital, because of acute MI in the last 12 years. One patient needed blood transfusion and in another patient, atypical ductal nuclei were observed in fine needle aspiration (FNA) of breast hematoma, needing further evaluation. As thrombolytic therapy becomes more widespread and essential in treating patients suffering acute occlusion of coronary, retinal, pulmonary or peripheral arteries, it is expected that more women will present with breast hematoma following such treatment.

Transient mitral regurgitation in acute glomerulonephritis.

During an epidemic of acute glomerulonephritis (AGN) 15 patients were studied by M-mode, cross-sectional, and Doppler echocardiography. All 15 patients had the classical signs of the disease including hematuria, proteinuria, edema, and consistent laboratory findings. There were 10 boys and five girls with a mean age of 8 years. Ten of the 15 patients had an enlarged left atrium and five of these 10 also had transient mild to moderate mitral regurgitation. In the five patients with mitral regurgitation the ratio of left atrium/aorta was 1.48; in the five patients with an enlarged left atria without evidence of mitral regurgitation the left atrium/aorta ratio was 1.34. All the patients had normal left ventricular dimensions, as well as ejection and shortening fractions. The findings of left atrial enlargement and mitral regurgitation disappeared gradually in all patients within 3 months. There was no correlation between the level of systemic blood pressure and the development of mitral regurgitation. A possible cause for these changes is fluid overload in the oliguric phase of the acute glomerulonephritis. The changes are transient and probably functional. There was no significant mitral valve or left atrial anomaly 3 and 6 months after hospital discharge.

Adult acute rheumatic fever: a rare case presenting with left bundle branch block.

In contrast to the more common electrocardiographic patterns seen in acute rheumatic fever, such as first-degree heart block, the appearance of left bundle branch block is rare. An adult patient with acute rheumatic fever presented with left bundle branch block on admission, subsequently had sudden cardiac arrest. She was resuscitated successfully and required temporary pacing. An echocardiogram and radionuclide ventriculography were compatible with interventricular septal involvement in the rheumatic carditis. After 20 days of steroid therapy, the left bundle branch block pattern of the electrocardiogram disappeared. A possible mechanism for the development of complete heart block in acute rheumatic fever is discussed. It is suggested that patients with acute rheumatic carditis who have electrocardiographic manifestations of prolonged P-R interval and left bundle branch block should be managed with prophylactic pacing.

Pacemaker implantation in a patient with a Behçet's disease associated with superior vena cava obstruction.

A 65-year-old man with Behçet's disease developed transient complete A-V block with syncope. An attempt to implant a permanent transvenous endocardial electrode failed owing to obstructions in the subclavian, innominate, and superior vena cava veins demonstrated by angiography. Sutureless epicardial electrodes were successfully implanted through a subxyphoid approach. Obstruction in the great veins is a common feature in patients with Behçet's disease. We suggest that patients with this disorder, who require a permanent pacemaker, should be investigated by angiography prior to implant to rule out obstruction in the upper great veins.

Atrioventricular block in situs ambiguus and left isomerism (polysplenia syndrome).

Three patients are described who had situs ambiguus and left isomerism (polysplenia syndrome) and advanced atrioventricular block. One presented with a complex bradyarrhythmia with Wenckebach block. The other two had congenital atrioventricular block with a narrow QRS at a ventricular rate of 80 per minute, an atrial rate of 150' per minute, and both had a P wave axis directed superiorly and to the right in one, and superiorly to the left in the other. This ECG pattern was not observed in more than 400 adult patients with complete A-V block treated in our service. It is our opinion that in infants and children with heart disease the presence of complete A-V block with narrow QRS and an unusual P waves axis directed superiorly is strongly suggestive of left isomerism. The incidence rate of complete A-V block in left isomerism is nearly twenty percent of the cases described.