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PubMed2002

Assessment of right heart function in the athlete's heart.

It is known that the heart of an athlete has been physiologically adapted by prolonged training. There are a large number of echocardiographic studies which have focused on left ventricular wall thickness and dilatation, but there are few studies concerning right heart function in the athlete's heart. The aim of this study was to assess right heart function in elite athletes by conventional and new echocardiographic methods. The study population consisted of 36 elite highly-trained male athletes and 16 age-matched healthy sedentary controls. Right atrial, right ventricular, and inferior vena cava dimensions, and pulsed Doppler measurements of tricuspid inflow and right ventricular outflow were obtained, and systolic (preejection period, ejection time, preejection time/ejection time, QV peak, isovolumic contraction time) and diastolic (E peak, A peak, E/A ratio, decelaration time, isovolumic relexation time) function parameters were measured. The myocardial performance index was calculated as (isovolumetric contraction time + isovolumetric relaxation time)/ejection time. In addition, right ventricular systolic and diastolic functions were determined by Pulsed wave tissue Doppler imaging (S, E, and A velocities) at the lateral corners of the tricuspid annulus. The left ventricular mass index (P < 0.005), and right atrial (P < 0.001), right ventricular (P < 0.001), and inferior vena cava dimensions (P < 0.001) were significantly greater in athletes than in controls. Tricuspid E peak, A peak, E/A ratio, deceleration time, isovolumic relaxation time, preejection period, right ventricular ejection time, preejection time/ejection time, isovolumic contraction time, QV peak, and myocardial performance index were found to be similar in athletes and in controls (P > 0.05). Systolic, early diastolic, and late diastolic tissue Doppler imaging velocities were not significantly different in athletes and controls (P > 0.05). Left ventricular hypertrophy (LV mass index >134 g/m2) was found in 15 of the athletes. Right atrial dimension was greater in the athletes with left ventricular hypertrophy than in those without hypertrophy (P < 0.05). All right ventricular systolic and diastolic echocardiographic parameters were similar in athletes with and without left ventricular hypertrophy (P > 0.05). The results of this study indicate that right ventricular systolic and diastolic functions do not deteriorate in the athlete's heart despite significant chamber dilatation. They suggest that these changes are a normal physiologic adaptation to prolonged training.

Adult↗
PubMed1986

The diisobutyryl ester of N-methyldopamine, ibopamine: evaluation of electrophysiological properties and arrhythmogenicity studies.

The electrophysiological properties of ibopamine (SB-7505), the 3,4-diisobutyryl ester N-methyldopamine, was evaluated in 8 patients with syncopes of unknown etiology or with suspected disease of the sinus node or due to I-II degree AV block. A complete electrophysiological examination, including atrial and ventricular stimulation, was performed both in baseline conditions and within 1 h after oral administration of ibopamine 200 mg in a single dose. The study showed a slight reduction in effective refractory periods in the right atrium (-4.26%), the atrio-ventricular node (-6.45%) and the right ventricle (-6.79%) after ibopamine. Ibopamine was not found to facilitate the occurrence of atrial and/or ventricular arrhythmias. A 24-h dynamic Holter ECG performed in baseline conditions and during administration of ibopamine 200 mg t.i.d. showed no changes in baseline heart rate, nor was any increase in the number of atrial or ventricular extrasystoles detectable. It may therefore be concluded that ibopamine, when administered at the above dosages to the patients studied, does not modify heart rate or sinus function parameters to a statistically significant extent. It also reduces effective refractory periods in the right atrium, in the atrioventricular node and in the right ventricle without inducing or facilitating the occurrence of atrial or ventricular arrhythmias.

Adult↗
PubMed1997

Risk factors for life-threatening cavopulmonary thrombosis in patients undergoing bidirectional superior cavopulmonary shunt: an exploratory study.

We have observed six patients with life-threatening superior vena caval or pulmonary thrombosis after bidirectional superior cavopulmonary shunt. With the use of a case control study we sought to identify perioperative risk factors for this thrombotic complication. Medical records of six patients with cavopulmonary thrombosis and those of 24 patients in a control group were reviewed to abstract data for potential risk factors. Contingency tables and univariate logistic regression were used to determine associations between various perioperative parameters and occurrence of cavopulmonary thrombosis. Preoperative variables associated with thrombosis included bilateral superior vena cavae, odds ratio: 23, p = 0.02, increased age at surgery (p = 0.05), and female sex (odds ratio: 7, p = 0.05). The McGoon Ratio (index of relative pulmonary artery branch diameter) was inversely related to thrombosis risk (p = 0.08). Two torr increases in mean right atrial (p = 0.08) or ventricular end-diastolic (p = 0.05) pressures were associated with approximately 70% increases in thrombosis risk. Intraoperative prolongation of aortic cross-clamp time related directly to thrombosis risk (p = 0.06). Postoperative variables associated with thrombosis included increased superior vena caval pressure within 12 hours after surgery (odds ratio > or = 10 for 5 torr increase in pressure, p = 0.02) and poor ventricular function (odds ratio: 9, p = 0.06) We conclude that high risk variables for patients undergoing a cavopulmonary shunt include bilateral superior vena cavae, female sex, increasing age, decreased McGoon Ratio, and elevated right atrial and ventricular end-diastolic pressure (before surgery), patients with prolonged aortic cross-clamp time (during surgery), and patients with elevated superior vena caval pressure and poor ventricular function (after surgery).

Adolescent↗
PubMedDate not supplied

Cardiovascular effects of intravenous diltiazem in dogs with iatrogenic atrial fibrillation.

Atrial fibrillation (AF) was induced in anesthetized Beagle hounds to determine the dose of diltiazem (D) that resulted in hemodynamic function similar to that observed during sinus rhythm (SR). Dogs were instrumented to record hemodynamic and electrophysiological parameters. Six dogs were given D, IV at cumulative doses of 0.063, 0.188, 0.438, 0.938, and 1.938 mg/kg, whereas 6 other dogs received vehicle in equivalent volumes. Plasma concentrations (PC) of D were measured. A cumulative dose of D between 0.438 and 0.938 mg/kg produced PC of 67.8 to 117.4 ng/mL and resulted in a heart rate (HR) closest to that observed during SR. At doses up to 0.938 mg/kg, no parameter of systolic function fell below that obtained during SR. At a dose of 0.938 mg/kg, the left ventricular end-diastolic and right atrial pressures exceeded those during SR. The rate-pressure product did not differ from that during SR at a dose of 0.938 mg/kg and fell below that during SR at the dose of 1.938 mg/kg. Left ventricular efficiency decreased from SR to AF, returned to values not different from those during SR at a dose of 0.938 mg/kg, and increased to values above those observed during SR at a dose of 1.938 mg/kg. In AF, slowing the HR with 0.438-0.938 mg/kg of D with resultant PC of 67.8-117.4 ng/mL results in cardiovascular function not different from that observed during SR.

Animals↗
PubMed1982

Reflexes elicited by acute stretch of atrial vs. pulmonary receptors in conscious dogs.

We measured hemodynamics and renal function in conscious dogs while partially obstructing blood flow at various sites within the thorax. Inflation of a balloon in the left atrium increased left atrial pressure (LAP) by 9 mmHg and caused a parallel increase in pulmonary arterial pressure (PAP); heart rate, arterial pressure, and total peripheral resistance increased; stroke volume and right atrial pressure decreased; and cardiac output remained unchanged. The increase in LAP was accompanied by a fourfold increase in urine flow and a threefold increase in sodium excretion. Plasma vasopressin (AVP) and renin activity (PRA) decreased. On the other hand, partial occlusion of the pulmonary veins or the main pulmonary artery produced similar increases in PAP without affecting LAP, systemic hemodynamics, renal function, or plasma AVP. Similarly, inflation of a balloon in the right atrium failed to alter renal function, plasma AVP, or PRA. Finally, constriction of the thoracic inferior vena cava decreased LAP and increased PRA. In summary, these data emphasize that inflation of a balloon in the left atrium of the conscious dog produces a composite response consisting of alterations in cardiovascular function, renal function, and circulating hormones. Moreover, our data indicate that the response is mediated by a reflex initiated from receptors located in the left atrium; we detected no evidence that receptors located in the pulmonary vasculature or right heart contribute to this response.

Animals↗
PubMed2006

Resuscitation and recovery from acute right ventricular failure using a percutaneous right ventricular assist device.

A number of techniques have been proposed for circulatory support in patients with severe right heart failure. We report on a patient with right ventricular (RV) infarction complicated by cardiogenic shock, who was resuscitated by the novel use of a percutaneous right ventricular assist device. The moribund patient had striking hemodynamic and clinical improvement after placement of a right atrial to pulmonary artery assist circuit. RV decompression for 3 days was accompanied by recovery of contractile function, and the patient was successfully weaned from the device. Future trials are needed to assess the effectiveness of the percutaneous ventricular assist device in patients with RV failure.

Acute Disease↗
PubMed1990

Pharmacological doses of atrial natriuretic peptide ameliorate the acute renal dysfunction induced by systemic hypoxemia.

The acute renal effects of systemic hypoxemia and the ability of atrial natriuretic peptide (ANP) to reverse these effects were assessed in seven anesthetized and mechanically ventilated adult rabbits. Throughout the experiment, arterial pH, PaCO2 and HCO3 remained unchanged. Hypoxemia induced a significant increase in rabbit-ANP plasma levels from 151 +/- 26 to 246 +/- 65 pg/ml. During the normoxemic period (PaO2 = 131 +/- 12 mm Hg), glomerular filtration rate (GFR), renal blood flow (RBF), renal vascular resistance (RVR) and urinary sodium excretion (UNaV) were similar in both kidneys. The subsequent hypoxemic period (PaO2 = 30 +/- 1 mm Hg) caused a decrease in right and left kidney function: GFR, -26 +/- 5 and -29 +/- 6%; RBF, -17 +/- 9 and -29 +/- 8%; RVR, +28 +/- 16 and +59 +/- 30%; urine flow rate, -38 +/- 6 and -36 +/- 6%; and UNaV, -51 +/- 7 and -50 +/- 7%, respectively. Human-ANP infusion in the left renal artery (100 ng/min) during sustained systemic hypoxemia induced a significant improvement in GFR (+57 +/- 18%), RBF (+21 +/- 8%), RVR (-20 +/- 7%), urine flow rate (+151 +/- 27%) and UNaV (+270 +/- 48%) in the left experimental kidney, as compared with the preceding hypoxemic period. In contrast, the function of the right control kidney remained impaired.

Animals↗
PubMed1991

The reflex control of vasopressin in haemodialysis patients.

We studied the reflex arginine vasopressin (AVP) response to hypotensive, isosmotic fluid subtraction (by isolated UF) in 14 uraemic patients on renal dialysis treatment: five with normal autonomic function and nine with autonomic involvement of various degrees. Fluid subtraction caused a comparable mean arterial pressure (MAP) decrease in the two groups. The reduction in right atrial pressure was inversely related with the severity of autonomic neuropathy (rs = -0.72, P = 0.004), being distinctly attenuated in the second group (P = 0.006). Plasma arginine vasopressin increased similarly in patients with normal autonomic function and in those with autonomic involvement. The response of patients with haemodialysis hypotension was similar to that of other patients. Reflex control of arginine vasopressin is preserved even in the presence of afferent/central neuropathy or more advanced, widespread autonomic damage in uraemic man. The data suggest that it is unlikely that altered release of arginine vasopressin is involved in the pathogenesis of haemodialysis hypotension.

Adult↗
PubMed1998

Predictors of successful radiofrequency catheter ablation of sinoatrial tachycardia.

Predictors of successful elimination of sinoatrial tachycardia (SAT) using radiofrequency current (RFC) were investigated in this report. Within 1991-1996 fourteen patients with SAT were subjected to electrophysiological study and radiofrequency catheter ablation (RFCA). Ten patients had sinoatrial reentrant tachycardia (SART), and four patients had chronic non-paroxysmal sinoatrial tachycardia (CNPSAT). The RFC (15-30 W, duration 10-30 sec) were applied during tachycardia in case of CNPSAT, and during sinus rhythm (SR) in case of SART. In 3 patients with SART RFC were delivered during tachycardia due to failing of RFC application, delivered during SR. During successful RFC attempts were noted: 1). In case of SART-transient development (3-6 sec) of SART (if RFC was delivered during SR), and acceleration of tachycardia rate with following termination of tachycardia (if application of RFC was performed during tachycardia); 2). In case of CNPSAT-transient development (4-7 sec) of low right atrial (3 patients) or junctional (1 patient) rhythm with rapid conversion to SR. All 14 patients have been free of tachycardia and have normal sinus node function during follow-up of 8-60 months. We conclude that predictors of successful elimination of SAT are: 1). In case of SART-acceleration of tachycardia rate before termination during RFC application (delivered during tachycardia), and transient development of SART during RFC application (delivered during SR); 2). In case of CNPSAT-transient development of low right atrial or junction rhythm (during application of RFC) with rapid conversion to SR.

Adolescent↗
PubMed2006

Interactive atrial neural network: Determining the connections between ganglionated plexi.

BACKGROUND: The electrophysiologic functions of the intrinsic cardiac autonomic nervous system (ANS) are not well understood. OBJECTIVES: The purpose of this study was to investigate the functional interactions between ganglionated plexi within the intrinsic cardiac ANS. METHODS: The hearts of 21 dogs were exposed via right and/or left thoracotomy to expose the (1) anterior right ganglionated plexi near the caudal end of the sinoatrial node, (2) inferior right ganglionated plexi at the junction of inferior vena cava and atria, and (3) superior left ganglionated plexi near the junction of left superior pulmonary vein and left pulmonary artery. Ganglionated plexi were stimulated at 0.6 to 8.0 V (square waves, 20 Hz, 0.1-ms duration). Sinus rate, AH interval during atrial pacing, and ventricular rate during atrial fibrillation were compared before and after ganglionated plexi stimulation and after their ablation. RESULTS: Anterior right ganglionated plexi stimulation induced significant AH prolongation and slowing of ventricular rate and sinus rate. When inferior right ganglionated plexi was ablated, slowing of sinus rate by anterior right ganglionated plexi stimulation was unaltered, but inhibition of AV conduction was eliminated. Superior left ganglionated plexi stimulation induced similar effects on sinus and AV nodal function, and sinus rate slowing was markedly attenuated by anterior right ganglionated plexi ablation. Ablation of both anterior right ganglionated plexi and inferior right ganglionated plexi eliminated AV conduction inhibition but not sinus rate slowing by superior left ganglionated plexi stimulation. CONCLUSION: This study provides functional evidence for the interconnections between ganglionated plexi to modulate sinus and AV nodal function, supporting clinical evidence that interconnections within the intrinsic cardiac ANS are critical elements in identifying the targets for atrial fibrillation ablation.

Animals↗
PubMed1989

Electrophysiologic characteristics of sudden QRS axis deviation during orthodromic tachycardia. Role of functional fascicular block in localization of accessory pathway.

We analyzed the effect of functional fascicular block (FFB) on ventriculoatrial conduction time (VACT) during orthodromic tachycardia (OT) in 32 patients with single accessory pathway (AP) of the Kent bundle type. The location of AP was left free wall (LFW-AP) in 21 patients, left posteroseptal in 6, right free wall in 2, and right anteroseptal in 3. FFB either alone or in combination with functional left or right bundle branch block (LBBB or RBBB) occurred predominantly at the onset of OT and was initiated with ventricular extrastimulus technique more often than with atrial extrastimulation. In patients with LFW-AP, isolated functional left anterior fascicular block (LAFB) produced significant prolongation in VACT (15-35 ms). A similar magnitude of VACT increase (20-35 ms) was also observed when LAFB was associated with RBBB. Although 25-45-ms prolongation in VACT occurred with functional LBBB and normal axis, an additional 20-55-ms VACT increase was seen when LAFB accompanied LBBB. Functional LAFB, alone or in combination with bundle branch block, however, did not prolong VACT in patients with other AP locations. Furthermore, left posterior fascicular block did not produce prolongation of VACT in any of the cases. It is concluded that in patients with the Wolff-Parkinson-White syndrome, evaluation of VACT during functional LAFB provides important information regarding AP localization and a clear separation of LFW-AP from all other locations.

Adolescent↗
PubMed1995

Modified operation technique for orthotopic heart transplantation.

Atrioventricular (AV) valve dysfunction with tricuspid regurgitation is a common finding after orthotopic heart transplantation (HTx). In 20 patients the heart transplantation was performed with bicaval anastomoses and the results were compared to the precedent 20 patients operated with the standard technique. The right atrium of the recipient was completely removed and the caval anastomoses were performed on the beating heart during reperfusion. Using an interrupted suture line, no stenoses at the venous anastomoses were seen as known from the early implantation technique in heart-lung transplantation. Due to a more stable sinus rhythm only 15% of the patients in the bicaval group needed prolonged pacing (> 30 min) versus 55% (P < 0.01) in the group with standard operation. One to 3 months after surgery the transthoracic echocardiographic evaluation of the AV valve function showed tricuspid valve regurgitation (TVR) in 20% of the patients with bicaval anastomoses versus 75% with a right atrial anastomosis (P < 0.001). Tricuspid valve regurgitation during the first 2 weeks (in 31% of recipients with bicaval and in 70% with atrial anastomoses) improved in all recipients with bicaval anastomoses and in 14% of the recipients with atrial anastomosis. The modification of the operation technique did not result in significantly longer bypass time (75 +/- 14 versus 68 +/- 14 min) and ischemia time (44 +/- 12 versus 41 +/- 9 min with local organ procurement and 111 +/- 24 versus 101 +/- 19 min with distant organ procurement). The AV valve function and the postoperative rhythm after orthotopic HTx can be improved by implanting the heart with bicaval anastomoses.

Adult↗
PubMed2006

Impact of atrial septal defect closure on right ventricular performance.

BACKGROUND: Atrial septal defect (ASD) closure is one of the most representative cardiac operations, but there have been few assessments of right ventricular (RV) performance during the perioperative period. METHODS AND RESULTS: Using transesophageal echocardiography with automated border detection system, the RV pressure - area (P-A) loops were measured in 6 patients immediately before and after an ASD closure. Multiple RV P-A loops obtained by the inferior vena cava occlusion technique were used to evaluate end-systolic maximal elastance (Ees), preload recruitable stroke work (MEW), external work (EW) and the systolic P-A area (PAA). Ees and MEW are indices of contractility, and PAA represents the total mechanical energy. RV Ees and MEW did not change after the operation (from 3.36 +/- 2.20 to 3.70 +/- 2.04 mmHg/cm2, p = 0.4; and from 10.3 +/- 5.0 to 10.5 +/- 4.5 mmHg, p = 0.8, respectively), whereas EW and PAA were significantly reduced (from 121.4 +/- 77.4 to 48.7 +/- 26.6 mmHg/cm2, p < 0.05; and from 274.8 +/- 212.8 to 92.7 +/- 52.8 mmHg/cm2, p < 0.05, respectively). ASD closure reduced the EW and total mechanical energy of the right ventricle without influencing contractility. CONCLUSIONS: These results indicate that ASD closure preserved RV function and reduced RV myocardial oxygen consumption. Assessment of the RV P-A relationship in the operating room demonstrates the beneficial effects of ASD closure on RV performance.

Adult↗
PubMed1985

Venoarterial bypass: a technique for spinal cord protection.

In the present study, we examined the effects of various levels of oxygen tension on spinal cord blood flow while using somatosensory evoked potentials to monitor spinal cord sensory function during hypoxia. In this experiment, six adult, mongrel dogs were heparinized and placed on right atrial-femoral artery bypass with an oxygenator in the bypass circuit. The aorta was cross-clamped proximal to the left subclavian artery, and bypass flow and fluid balance were adjusted so as to maintain a distal aortic perfusion pressure of greater than 80 mm Hg. Oxygen flow to the oxygenator was lowered by graded decrements to provide decreasing levels of oxygen tension, which ultimately approached pure venoarterial bypass. Each successive oxygen level was maintained for 30 minutes. Spinal cord blood flow was measured with radioactive microspheres, and latency and amplitude of somatosomatic evolved potentials were continuously monitored. The somatosensory evolved potential signal was invariably present as long as the distal aortic pressure was greater than 80 mm Hg; there were several transient hypotensive episodes (less than 5 minutes), which were accompanied by reversible loss of somatosensory evolved potentials. The spinal cord blood flow increased from 13.6 to 119.7 ml/100 gm/min as the distal oxygen tension fell to a mean value of 30 mm Hg, while latency of somatosensory evolved potentials increased 19.3% and amplitude decreased 43.3%. These results suggest the following conclusions: (1) In response to hypoxia, spinal cord blood flow dramatically increases and somatosensory evolved potentials deteriorate (increase in latency and decrease in amplitude). (2) However, during prolonged hypoxia, spinal cord sensory function can be maintained by sufficiently high flow rates and perfusion pressures. (3) Somatosensory evolved potentials can be used to monitor continuously spinal cord sensory function under these conditions.

Animals↗